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Papers by Dale Bauman

British Journal of Nutrition, Feb 1, 2003

Thirty female Large White £ Landrace pigs (average weight 57•2 (SD 1•9) kg) were allocated to one... more Thirty female Large White £ Landrace pigs (average weight 57•2 (SD 1•9) kg) were allocated to one of six dietary treatments containing 0, 1•25, 2•5, 5•0, 7•5 or 10•0 g 55 % conjugated linoleic acids (CLA) isomers (CLA-55)/kg diet and fed for 8 weeks. Each pig was scanned at 0, 28 and 56 d and again at post slaughter using dual-energy X-ray absorptiometry (DXA) to determine the temporal pattern of body composition responses. Values determined by DXA were adjusted using regression equations generated from validation experiments between chemically and DXA-predicted values. Overall, there was a significant linear reduction in fat content with the increasing levels of CLA in the diet (P¼0•007, P¼0•011, P¼ 0•008 at week 4, week 8 and for the carcass, respectively). The greatest improvement was recorded at the early stages of CLA supplementation and for the highest dose of CLA (week 4, 219•2 % compared with week 8, 2 13•7 %). In the first 4 weeks of feeding CLA, pigs receiving 10 g CLA-55/kg diet deposited 93 g less fat/d than pigs fed basal diets (P¼0•002) compared with only 6 g less fat than control animals in the final 4 weeks. Lean content and lean deposition rate were maximised at 5 and 2•5 g CLA-55/kg diet for the first 4 weeks (P¼ 0•016) and the final 4 weeks of treatment ðP ¼ 0•17Þ; respectively. DXA estimates of bone mineral content and bone mineral density were not affected by CLA supplementation throughout the experiment. These data demonstrate that dietary CLA decreases body fat in a dose-dependent manner and that the response is greatest over the initial 4 weeks of treatment.

Journal of Dairy Science, Jul 1, 2002

Trans-10, cis-12 conjugated linoleic acid (CLA) is a potent inhibitor of milk fat synthesis. We e... more Trans-10, cis-12 conjugated linoleic acid (CLA) is a potent inhibitor of milk fat synthesis. We examined the effect of low doses of trans-10, cis-12 CLA using Holstein cows in a 4 × 4 Latin square design. Milk yield and milk protein were unaffected, but abomasal infusion of 1.25, 2.5, and 5.0 g/d of trans-10, cis-12 CLA reduced milk fat yield by 7, 16, and 29%, respectively. When combined with previous data, the reduction in milk fat yield was curvilinear, relating to both quantity infused and milk fat content of trans-10, cis-12 CLA (R 2 = 0.99 and 0.96, respectively). Further, changes in milk fatty acid composition indicated the mechanism involved inhibition of de novo fatty acid synthesis and the utilization of circulating fatty acids.

Journal of Nutrition, Sep 1, 2003

The present study was designed to examine the effects of increasing dietary levels of vaccenic ac... more The present study was designed to examine the effects of increasing dietary levels of vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acid (CLA) on chemically induced mammary carcinogenesis in rats. Both fatty acids were provided as a natural component in butter fat. The conversion of VA to CLA by ⌬9-desaturase was documented previously in several species, including rats and humans. Specifically, our objective was to determine the relative contribution of dietary VA and CLA to the tissue concentration of CLA and its ability to inhibit the development of mammary carcinomas. A total of 7 diets were formulated with varying levels of CLA and VA. The overall dietary treatment scheme was designed to evaluate the modulation of mammary cancer risk by 1) small increases of CLA in the presence of a low level of VA and 2) more substantial increases of VA against a background of low levels of CLA. As expected, small increases in dietary CLA at the low end of the CLA dose-response range did not reduce tumorigenesis. In contrast, there was a distinct and marked inhibitory response to VA that was dose dependent. The effect of VA was magnified in this experiment because the dose range of VA tested was much broader than that of CLA. Fatty acid analysis showed that the conversion of dietary VA to CLA resulted in a dose-dependent increase in the accumulation of CLA in the mammary fat pad, which was accompanied by a parallel decrease in tumor formation in the mammary gland. The finding confirms that the conversion of VA to CLA is as important for cancer prevention as the dietary supply of CLA. Thus, VA is also anticarcinogenic, and VA and CLA represent functional food components that are present in ruminant fat.

Latin American Archives of Animal Production, Dec 27, 2019

Resumen. El efecto antilipogénico del ácido linoleico conjugado (CLA) se ha evaluado en la vaca l... more Resumen. El efecto antilipogénico del ácido linoleico conjugado (CLA) se ha evaluado en la vaca lechera, hipotetizándose que el CLA afecta la síntesis de novo, pero por no ser la principal ruta de síntesis de ácidos grasos (AG), se desconoce a qué nivel el CLA está inhibiendo dicha síntesis. En las conejas la síntesis de novo es la principal ruta de la síntesis de AG pero se desconoce si el CLA cambia la composición química de su leche o altera el perfil de sus AG, por lo que en este estudio se evaluó el efecto de la suplementación oral del CLA sobre la composición química y el perfil de los AG de la leche de conejas durante los primeros 12 dias de lactancia. Se emplearon 18 conejas Nueva Zelanda asignadas al azar entre el tratamiento 1) grupo control; y el tratamiento 2) suplementación oral de 310 mg CLA/kg de peso metabólico. A partir del día 5 y hasta el 12 postparto, se administró diariamente vía oral el CLA (Tonalin FFA, BASF®) y se obtuvieron muestras individuales de leche obtenidas por ordeña manual. El perfil de los AG se determinó por cromatografía de gases y cuantificados empleando estándares internos. El CLA suplementado no alteró la composición química de la leche de las conejas, pero modificó el perfil de los AG de la grasa de leche reduciendo los AG de cadena larga mono-insaturados y poli-insaturados e incrementando la concentración de C 21:0 y de los isómeros de C 18:2 , CLA cis9,trans11 y CLA trans-10,cis-12.

Journal of Dairy Science, 2011

Consumers are increasingly aware that food components have the potential to influence human healt... more Consumers are increasingly aware that food components have the potential to influence human health maintenance and disease prevention, and dietary fatty acids (FA) have been of special interest. It has been 25 years since the last survey of US milk FA composition, and during this interval substantial changes in dairy rations have occurred, including increased use of total mixed rations and byproduct feeds as well as the routine use of lipid and FA supplements. Furthermore, analytical procedures have improved allowing greater detail in the routine analysis of FA, especially trans FA. Our objective was to survey US milk fat and determine its FA composition. We obtained samples of fluid milk from 56 milk processing plants across the US every 3 mo for one year to capture seasonal and geographical variations. Processing plants were selected based on the criteria that they represented 50% or more of the fluid milk produced in that area. An overall summary of the milk fat analysis indicated that saturated fatty acids comprised 63.7% of total milk FA with palmitic and stearic acids representing the majority (44.1 and 18.3% of total saturated fatty acids, respectively). Unsaturated fatty acids were 33.2% of total milk FA with oleic acid predominating (71.0% of total unsaturated fatty acids). These values are comparable to those of the previous survey in 1984, considering differences in analytical techniques. Trans FA represented 3.2% of total FA, with vaccenic acid being the major trans isomer (46.5% of total trans FA). Cis-9, trans-11 18:2 conjugated linoleic acid represented 0.55% total milk FA, and the major n-3 FA (linolenic acid, 18:3) composed 0.38%. Analyses for seasonal and regional effects indicated statistical differences for some FA, but these were minor from an overall human nutrition perspective as the FA profile for all samples were numerically similar. Overall, the present study provides a valuable database for current FA composition of US fluid milk, and results demonstrate that the milk fatty acid profile is remarkably consistent across geographic regions and seasons from the perspective of human dietary intake of milk fat.

Journal of Dairy Science, Jun 1, 2009

The feeding of conjugated linoleic acid (CLA) supplements to early-lactation dairy cows has been ... more The feeding of conjugated linoleic acid (CLA) supplements to early-lactation dairy cows has been shown to decrease milk fat synthesis and possibly improve reproductive performance. However, previously reported studies used too few animals to clearly establish the effect of CLA on reproduction. Our objective was to combine data from these studies to evaluate the association of CLA with time to first ovulation and time to conception using methods of survival analysis and overall success of pregnancy by logistic regression. A database was compiled of individual animal data (n = 212) from 5 controlled studies in which CLA had been supplemented to early-lactation dairy cows. Survival analysis incorporated both semi-parametric models (Cox proportional hazards) and parametric models (log-normal). The probability of cows becoming pregnant increased in a nonlinear manner as trans-10, cis-12 CLA dose increased, with the optimal dose predicted to be 10.1 g/d. At the optimal dose, the probability of pregnancy was increased by 26% compared with those animals receiving no CLA (probability = 91% and 72%, respectively). Similarly, the log-normal model predicted that time to conception was decreased in a nonlinear manner with increasing trans-10, cis-12 CLA dose. The predicted optimal dose was 10.5 g of trans-10, cis-12 CLA/d and at this dose the median time to conception was decreased by 34 d when compared with those cows not receiving CLA (117 vs. 151 d in milk, respectively). The log-normal model was also the best-fit model for time to first ovulation. Overall, this multi-study analy-sis demonstrated a strong concordance between the nature of the dose response and the predicted optimal dose of trans-10, cis-12 CLA across the 3 reproductive variables evaluated. These results indicate that reproductive performance of dairy cows may be improved by feeding of CLA supplements during early lactation.

British Journal of Nutrition, Mar 1, 2005

The aim of this study was to determine whether dietary supplementation with branched-chain amino ... more The aim of this study was to determine whether dietary supplementation with branched-chain amino acids, and the infusion of insulin and dextrose, would increase milk protein secretion in the sow. The experiment involved sixteen lactating sows fed either a normal lactation diet (162 g/kg crude protein, n 8) or a high-protein diet (230 g/kg crude protein, n 8) supplemented with branched-chain amino acids (valine, isoleucine and leucine). Sows were either infused with insulin and dextrose or not infused at all during mid (day 5-10) and late (day 17-22) lactation in a single reversal design. Blood samples were analysed for glucose, and the dextrose infusion rate was adjusted to maintain the blood glucose level within 15 % of pre-infusion levels. Milk (10•1 v. 11•1 kg/d; P¼0•014) and lactose (628 v. 727 g/d; P¼0•002) yield increased with insulin infusion, whereas milk protein content (5•0 % v. 5•5 %; P¼0•007) was increased in diets supplemented with protein and branched-chain amino acids. Piglet growth was increased by feeding the higher-protein diet (237 v. 273 g/d; P¼0•05) but not significantly increased by insulin infusion (245 v. 265 g/d; P¼0•11). These effects were additive such that the combined treatment resulted in a 24 % (56 g/d; P,0•05) increase in piglet growth rate. These data demonstrate that increasing the dietary protein/branched-chain amino acid content can increase milk protein secretion but not milk yield. The infusion of insulin and dextrose increased milk and milk lactose yields, and tended to increase milk protein yield but not milk protein content. These effects are additive and translate to increased protein yield and piglet growth.

MAMMARY GLAND, MILK BIOSYNTHESIS AND SECRETION | Milk Fat

Elsevier eBooks, 2011

Fat is an important component of milk. Nutritionally, fat is the major energy component of milk a... more Fat is an important component of milk. Nutritionally, fat is the major energy component of milk and accounts for many of the physical properties, manufacturing characteristics, and sensory attributes of dairy products. Economically, fat is important to the value of milk as it directly affects the yield of many manufactured dairy products. Additionally, fat is the major energy cost in milk synthesis and significant feed costs are associated with meeting the energy demand. Finally, recent research on milk fat has included a focus on ‘designing’ milk fat to improve its healthfulness and functional properties.

Biosynthesis and biological activity of rumenic acid: a natural CLA isomer

Elsevier eBooks, 2012

Nutrition Research, Jul 1, 2008

Human breast milk is a complex mixture of organic and inorganic compounds. Some compounds, such a... more Human breast milk is a complex mixture of organic and inorganic compounds. Some compounds, such as conjugated linoleic acid (CLA), come partly from the mother's diet and are produced by the mother's body and secreted into the milk. Although several studies have examined the effect of chronic CLA supplementation on breast milk CLA appearance, little is known about the transfer of food CLA to breast milk over the short term. The objective of this study was to conduct a preliminary analysis of the kinetics of CLA appearance in breast milk over the short term. Seven women expressed breast milk at 4-to 6-hour intervals for 2 days after eating either CLA-enriched (1912 mg CLA) or control (231 mg CLA) cookies. Milk samples were freeze-dried, fatty acid methyl esters were prepared using methanolic-potassium hydroxide (KOH), and CLA isomers were quantified by gas chromatography. Analysis revealed the following: (1) CLA enrichment of total fatty acids in the breast milk for 48 hours post ingestion of the CLA-enriched cookies was 2.9-fold above control; (2) total breast milk CLA content for 48 hours post CLA-enriched cookies ingestion was 46% greater than post CLA-moderate cookies ingestion; (3) after ingestion of the CLA-enriched cookies, breast milk CLA enrichment plateaued between 8 to 28 hours. This preliminary study suggests that breast milk fatty acids are enriched in CLA compared to control within 28 hours after the ingestion of a CLA-rich food product and invites further research on the extent and timing with which breast milk composition reflects dietary CLA content.

Journal of Dairy Science, Aug 1, 2018

Trans-10,cis-12 conjugated linoleic acid (CLA) has been identified as an intermediate of rumen fa... more Trans-10,cis-12 conjugated linoleic acid (CLA) has been identified as an intermediate of rumen fatty acid biohydrogenation that caused milk fat depression (MFD) in the dairy cow. Previous studies in cows experiencing CLA-and diet-induced MFD have identified reduced mammary expression of the master lipogenic regulator sterol response element transcription factor 1 (SREBF1) and many of its dependent genes. To distinguish between primary mechanisms regulating milk fat synthesis and secondary adaptations to the reduction in milk fat, we conducted a time-course experiment. Eleven dairy cows received by abomasal infusion an initial priming dose of 6.25 g of CLA followed by 12.5 g/d delivered in multiple pulses per day for 5 d. Cows were milked 3×/d and mammary biopsies were obtained under basal condition (prebolus control) and 12, 30, and 120 h relative to initiation of CLA infusion. Milk fat concentration and yield decreased progressively reaching a nadir at 69 h (1.82% and 38.2 g/h) and averaged 2.03 ± 0.19% and 42.1 ± 4.10 g/h on the last day of treatment (±standard deviation). Expression of fatty acid synthase (FASN) and lipoprotein lipase (LPL) were decreased at 30 and 120 h compared with control. Expression of SREBF1 and THRSP were also decreased at 30 and 120 h compared with control. Additionally, we failed to observe changes in other factors, including peroxisome proliferator-activated receptor γ and liver x receptor β and milk fat globular membrane proteins, during CLA treatment. However, expression of milk fat globular membrane proteins were decreased after 14 d of diet-induced MFD in samples from a previous experiment, indicating a possible long-term response. The rapid decrease in lipogenic enzymes, SREBF1, and THRSP provide strong support for their transcriptional regulation as a primary mechanism of milk fat depression.

American Journal of Physiology-regulatory Integrative and Comparative Physiology, Dec 1, 2010

The trans 10, cis 12-conjugated linoleic acid (10,12-CLA) isomer reduces adiposity in several ani... more The trans 10, cis 12-conjugated linoleic acid (10,12-CLA) isomer reduces adiposity in several animal models. In the mouse, however, this effect is associated with adipose tissue inflammation, hyperinsulinemia and hepatic lipid accumulation. Moreover, 10,12-CLA was recently shown to promote mammary ductal hyperplasia and ErbB2/Her2-driven mammary cancer in the mouse. Reasons for detrimental effects of 10,12-CLA on the mouse mammary gland could relate to its effect on the mammary fat pad (MFP), which is essential for normal development. Accordingly, we hypothesized that mammary effects of 10,12-CLA were mediated through the MFP in a dose-dependent manner. Female FVB mice were fed 10,12-CLA at doses of 0%, 0.1%, 0.2%, or 0.5% of the diet from day 24 of age, and effects on mammary development and metabolism were measured on day 49. The 0.5% dose reduced ductal elongation and caused premature alveolar budding. These effects were associated with increased expression of inflammatory markers and genes shown to alter epithelial growth (IGF binding protein-5) and alveolar budding (TNF-␣ and receptor of activated NF-B ligand). The 0.5% dose also caused hyperinsulinemia and hepatic lipid accumulation. In contrast, the 0.1% 10,12-CLA dose had no adverse effects on mammary development, metabolic events, and inflammatory responses, but remained effective in decreasing adipose weights and lipogenic gene expression. These results show that a low dose of 10,12-CLA reduces adiposity in the mouse without negative effects on mammary development, inflammation, and metabolism, and suggest that previously reported detrimental effects relate to the use of excessive doses. mammary fat pad; ductal growth; fatty liver; lipogenic gene expression CONJUGATED LINOLEIC ACIDS (CLA) consist of positional and geometric isomers of octadecadienoic fatty acids with a conjugated double bond. They are produced by microbial hydrogenation of polyunsaturated fatty acids in the rumen of cattle, goats, and sheep, and accordingly, they occur in trace amounts in ruminant products (Ͻ0.5% of all fatty acids). Over 70% of CLA found in animal products is accounted for by the cis 9, trans 11 isomer (9,11-CLA) and the rest by a collection of minor isomers that includes t10, c12-CLA (10,12-CLA) (25). CLA can also be produced by chemical methods, such as heat alkaline isomerization of linoleic acid. This produces a mixture of CLA isomers

Domestic Animal Endocrinology, Jul 1, 1991

Insulin-like growth factor I (IGF-I) circulates in serum bound to a number of different binding p... more Insulin-like growth factor I (IGF-I) circulates in serum bound to a number of different binding proteins (BPs). With antibodies currently available, BPs must be dissociated and inactivated or removed from serum prior to measurement of IGF-I by radioimmunoassay (RIA). Serum samples which spanned a 13-fold range in IGF-I concentration were obtained from lactating dairy cows and used to develop conditions for assay of IGF-I with minimal interference from BPs. Removal of BPs from serum by acid-ethanol extraction resulted in interference in the RIA. Therefore, serum was incubated with 0.1 M glycyl-glycine HCI to inactivate BPs as suggested by Underwood et al. . Time, temperature and pH were optimum when serum was incubated for 48 hr at 37 C, pH 3.7. Binding protein inactivation was evaluated by ability of glycyl-glycine incubated serum to reassociate with t25I-IGF-I. In addition, BPs isolated by gel filtration of glycyl-glycine incubated serum were tested for interference in the RIA. The concentration of IGF-I in serum where inactivated BPs were removed by acid gel filtration was compared to corresponding glycyl-glycine incubated serum. There was a 1:1 relationship which intersected at zero indicating that total IGF-I could be measured. Therefore, incubation of serum with glycylglycine is a reliable method for measuring total IGF-I in serum from dairy cows.

Journal of Dairy Science, 2007

The study was designed to test the effects of feeding fish meal (FM) and specific n-3 fatty acids... more The study was designed to test the effects of feeding fish meal (FM) and specific n-3 fatty acids on milk yield and composition, dry matter intake, plasma concentrations of metabolic hormones and metabolites, and liver triglyceride accumulation in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden FM or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Milk yield (48.2, 49.8, 48.6, 53.5, and 52.2 ± 1.0 kg/d, respectively) and dry matter intake (22.7, 22.8, 23.0, 23.8, and 24.7 ± 0.5 kg/d, respectively) differed among diets. Average daily plasma glucose concentration (53.4, 55.3, 51.1, 57.6, and 57.3 ± 1.3 mg/dL, respectively) was also affected by diet, and plasma insulin concentration was increased by 5% FM and 2.3% Ca-FOFA. At 25 and 50 DIM, blood was collected before feeding and hourly for 11 h after feeding. Plasma glucose concentrations in cows during the day were similar among diets at 25 DIM, but differed at 50 DIM (54.6, 54.4, 52.4, 60.5, and 58.3 ± 1.4 mg/dL for 0, 1.25, 2.5, and 5% FM or 2.3% CaFOFA, respectively). Plasma insulin was increased in cows fed 5% FM and 2.3% CaFOFA at 25 DIM and was similar among diets at 50 DIM. Dietary treatments had no significant effect on milk composition, energy balance, or on daily plasma concentrations of nonesterified fatty acids, βhydroxybutyrate, and urea. Plasma aspartate aminotransferase and hepatic triglyceride concentration in cows did not differ among diets at 21 DIM. Results from this experiment demonstrate that dietary supplementation with FM or n-3 polyunsaturated fatty acids in early lactating dairy cows significantly increased milk yield and DMI with no change in milk composition.

Journal of Dairy Science, 2007

The study was designed to test the effects of dietary supplementation with fish meal or specific ... more The study was designed to test the effects of dietary supplementation with fish meal or specific n-3 fatty acids on ovarian activity and uterine responses in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden fish meal (FM) or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Ovarian follicular dynamics were monitored along with plasma concentrations of estradiol and progesterone. Beginning at 23 DIM, cows were induced into a synchronized ovulatory cycle. On d 15 after ovulation (49 DIM), cows were injected with oxytocin and blood samples were collected to monitor uterine release of PGF 2α (measured as 13, 14-dihydro-15-keto PGF 2α ; PGFM). Uterine endometrial biopsies were collected for fatty acid analysis and cyclooxygenase-2 (COX-2) protein measurement. Ovarian follicular activities as well as plasma estradiol and progesterone concentrations were similar across diets. Endometrial fatty acid composition of eicosapentaenoic acid (C20:5, n-3) and docosahexaenoic acid (C22:6, n-3) were increased as much as 3-fold by supplementation with fish meal and CaFOFA. Conjugated linoleic acid (C18:2 cis-9, trans-11) in the endometrium was also increased; conversely, arachidonic acid (C20:4, n-6) percentage was decreased by 5% FM. Plasma PGFM response to oxytocin injection was not different among diets and endometrial COX-2 protein abundance did not differ. Results from this experiment demonstrate that dietary supplementation with fish meal or n-3 fatty acids in early lactating dairy cows significantly increased uterine n-3 fatty acid concentrations, but had no apparent effect on endometrial COX-2 or PGF 2α production in response to oxytocin challenge.

Journal of Dairy Science, Sep 1, 2007

The objective of this study was to evaluate the mechanism of action through which conjugated lino... more The objective of this study was to evaluate the mechanism of action through which conjugated linoleic acid (CLA) beneficially affects reproduction. Lactating Holstein cows (n = 45, 20 ± 1 DIM) were assigned to 1 of 3 treatments: 70 g/d of Ca salts of tallow (control); 63 g/d of lipid-encapsulated CLA providing 7.1 g/d of cis-9, trans-11 CLA and 2.4 g/d of trans-10, cis-12 CLA (CLA 75:25); or 76 g/d of lipid-encapsulated CLA providing 7.1 g/d each of cis-9, trans-11 and trans-10, cis-12 CLA (CLA 50:50). Supplements were top-dressed for 37 d, milk production and DMI were recorded daily, and blood samples were taken 3 times per week. At 30 ± 3 DIM, ovulation was synchronized in all cows with a modified Ovsynch protocol, and on d 15 of the cycle cows received an oxytocin injection; blood samples were obtained frequently to measure 13,14 dihydro, 15-keto PGF 2α . On d 16 of the cycle cows received a PGF 2α injection and ovarian follicular aspiration was performed 54 h later. Follicular fluid was analyzed for fatty acids, progesterone, and estradiol. Endometrial biopsies were taken before and again near the end of the supplementation period for fatty acid analysis. The CLA resulted in decreased milk fat content of 14.1 and 6.1% at wk 5 of treatment of CLA 50:50 and CLA 75:25, respectively. There were no differences in energy balance or plasma nonesterified fatty acids; however, plasma IGF-I was greater in cows supplemented with CLA 50:50. The CLA isomers were not detectable in

Effect of CLA on milk fat synthesis in dairy cows: Comparison of inhibition by methyl esters and free fatty acids, and relationships among studies

Lipids, Apr 1, 2004

CLA is a potent inhibitor of milk fat synthesis, as shown by investigations using mixtures of CLA... more CLA is a potent inhibitor of milk fat synthesis, as shown by investigations using mixtures of CLA isomers in FFA form. However, methyl esters of CLA can be initially formed in commercial synthesis, and their use in a supplement has certain manufacturing and cost advantages. Our objective was to compare abomasal infusion of methyl esters of CLA (ME‐CLA) and FFA of CLA (FFA‐CLA) on milk fat synthesis. Data were also combined with previous investigations to examine broader relationships between trans‐10,cis‐12 CLA and the reduction in milk fat. Three mid‐lactation, rumen‐fistulated Holstein cows were used in a 3×3 Latin square design. Treatments were (i) control, (ii) ME‐CLA, and (iii) FFA‐CLA. The ME‐CLA and FFA‐CLA treatments (4.2 g/d trans‐10,cis‐12 CLA) resulted in a comparable reduction in milk fat yield (38 and 39%, respectively) and pattern of reduction in individual FA. In contrast, milk yield, milk protein, and feed intake were unaltered by CLA treatment. Combining data across studies revealed strong correlations relating the reduction in milk fat yield to abomasal dose of trans‐10,cis‐12 CLA (R2=0.86), milk fat content of trans‐10,cis‐12 CLA (R2=0.93), and milk fat secretion of trans‐10,cis‐12 CLA (R2=0.82). Across studies, transfer efficiency of abomasally infused trans‐10,cis‐12 CLA into milk fat was relatively constant (22%; R2=0.94). Overall, ME‐CLA and FFA‐CLA were equally potent in reducing milk fat, and either form could be used to formulate a dietary supplement that would induce milk fat depression.

Physiological Reviews, Jan 7, 1998

Impressive progress has been made during the past 15 years in our understanding of the biology of... more Impressive progress has been made during the past 15 years in our understanding of the biology of somatotropin (ST) in domestic animals. In part, this progress was sparked by advances in biotechnology that made feasible the production of large quantities of recombinant bovine ST (bST) and porcine ST (pST). The availability of recombinant bST and pST resulted in an exponential increase in investigations that explored their role in growth and lactation biology, as well as evaluated their potential for commercial use. Collectively, these studies established that administration of bST to lactating dairy cows increased milk yield, and treatment of growing pigs with pST markedly stimulated muscle growth and reduced fat deposition. In addition to these ''efficacy'' studies, a substantial number of investigations examined the mechanisms by which ST affects lactation and growth of domestic animals. This review summarizes the diverse physiological effects ST has on growth and lactation and discusses the underlying mechanisms that mediate these effects in domestic animals.

American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2000

Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis. Am. J. Ph... more Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R179-R184, 2000.-Conjugated linoleic acids (CLA) are octadecadienoic fatty acids that have profound effects on lipid metabolism. Our previous work showed that CLA (mixture of isomers) markedly reduced milk fat synthesis. In this study, our objective was to evaluate the effects of specific CLA isomers. Multiparous Holstein cows were used in a 3 ϫ 3 Latin square design, and treatments were 4-day abomasal infusions of 1) skim milk (control), 2) 9,11 CLA supplement, and 3) 10,12 CLA supplement. CLA supplements provided 10 g/day of the specific CLA isomer (cis-9,trans-11 or trans-10,cis-12). Treatments had no effect on intake, milk yield, or milk protein yield. Only the 10,12 CLA supplement affected milk fat, causing a 42 and 44% reduction in milk fat percentage and yield, respectively. Milk fat composition revealed that de novo synthesized fatty acids were extensively reduced. Increases in ratios of C 14:0 to C 14:1 and C 18:0 to C 18:1 indicated the 10,12 CLA supplement also altered ⌬ 9 -desaturase. Treatments had minimal effects on plasma concentrations of glucose, nonesterified fatty acids, insulin, or insulin-like growth factor-I. Overall, results demonstrate that trans-10,cis-12 CLA is the isomer responsible for inhibition of milk fat synthesis. lactation; fatty acids; ruminants CONJUGATED LINOLEIC ACIDS (CLA) are octadecadienoic acids that are found predominately in food products derived from ruminant animals. They have been implicated in a wide range of beneficial effects, including anticarcinogenic, antidiabetic, and immune stimulation (2, 18). CLA have also been shown to reduce body fat and alter nutrient partitioning in growing animals, including mice and pigs . However, all of these biological effects have been observed using dietary supplements that contain a variety of CLA isomers, and effects of specific isomers are unknown. CLA administration also affects lipid synthesis in lactating cows, resulting in marked reductions in milk fat secretion . Several dietary situations, such as high-concentrate, low-fiber diets or increasing in-

British Journal of Nutrition, Feb 1, 2003

Thirty female Large White £ Landrace pigs (average weight 57•2 (SD 1•9) kg) were allocated to one... more Thirty female Large White £ Landrace pigs (average weight 57•2 (SD 1•9) kg) were allocated to one of six dietary treatments containing 0, 1•25, 2•5, 5•0, 7•5 or 10•0 g 55 % conjugated linoleic acids (CLA) isomers (CLA-55)/kg diet and fed for 8 weeks. Each pig was scanned at 0, 28 and 56 d and again at post slaughter using dual-energy X-ray absorptiometry (DXA) to determine the temporal pattern of body composition responses. Values determined by DXA were adjusted using regression equations generated from validation experiments between chemically and DXA-predicted values. Overall, there was a significant linear reduction in fat content with the increasing levels of CLA in the diet (P¼0•007, P¼0•011, P¼ 0•008 at week 4, week 8 and for the carcass, respectively). The greatest improvement was recorded at the early stages of CLA supplementation and for the highest dose of CLA (week 4, 219•2 % compared with week 8, 2 13•7 %). In the first 4 weeks of feeding CLA, pigs receiving 10 g CLA-55/kg diet deposited 93 g less fat/d than pigs fed basal diets (P¼0•002) compared with only 6 g less fat than control animals in the final 4 weeks. Lean content and lean deposition rate were maximised at 5 and 2•5 g CLA-55/kg diet for the first 4 weeks (P¼ 0•016) and the final 4 weeks of treatment ðP ¼ 0•17Þ; respectively. DXA estimates of bone mineral content and bone mineral density were not affected by CLA supplementation throughout the experiment. These data demonstrate that dietary CLA decreases body fat in a dose-dependent manner and that the response is greatest over the initial 4 weeks of treatment.

Journal of Dairy Science, Jul 1, 2002

Trans-10, cis-12 conjugated linoleic acid (CLA) is a potent inhibitor of milk fat synthesis. We e... more Trans-10, cis-12 conjugated linoleic acid (CLA) is a potent inhibitor of milk fat synthesis. We examined the effect of low doses of trans-10, cis-12 CLA using Holstein cows in a 4 × 4 Latin square design. Milk yield and milk protein were unaffected, but abomasal infusion of 1.25, 2.5, and 5.0 g/d of trans-10, cis-12 CLA reduced milk fat yield by 7, 16, and 29%, respectively. When combined with previous data, the reduction in milk fat yield was curvilinear, relating to both quantity infused and milk fat content of trans-10, cis-12 CLA (R 2 = 0.99 and 0.96, respectively). Further, changes in milk fatty acid composition indicated the mechanism involved inhibition of de novo fatty acid synthesis and the utilization of circulating fatty acids.

Journal of Nutrition, Sep 1, 2003

The present study was designed to examine the effects of increasing dietary levels of vaccenic ac... more The present study was designed to examine the effects of increasing dietary levels of vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acid (CLA) on chemically induced mammary carcinogenesis in rats. Both fatty acids were provided as a natural component in butter fat. The conversion of VA to CLA by ⌬9-desaturase was documented previously in several species, including rats and humans. Specifically, our objective was to determine the relative contribution of dietary VA and CLA to the tissue concentration of CLA and its ability to inhibit the development of mammary carcinomas. A total of 7 diets were formulated with varying levels of CLA and VA. The overall dietary treatment scheme was designed to evaluate the modulation of mammary cancer risk by 1) small increases of CLA in the presence of a low level of VA and 2) more substantial increases of VA against a background of low levels of CLA. As expected, small increases in dietary CLA at the low end of the CLA dose-response range did not reduce tumorigenesis. In contrast, there was a distinct and marked inhibitory response to VA that was dose dependent. The effect of VA was magnified in this experiment because the dose range of VA tested was much broader than that of CLA. Fatty acid analysis showed that the conversion of dietary VA to CLA resulted in a dose-dependent increase in the accumulation of CLA in the mammary fat pad, which was accompanied by a parallel decrease in tumor formation in the mammary gland. The finding confirms that the conversion of VA to CLA is as important for cancer prevention as the dietary supply of CLA. Thus, VA is also anticarcinogenic, and VA and CLA represent functional food components that are present in ruminant fat.

Latin American Archives of Animal Production, Dec 27, 2019

Resumen. El efecto antilipogénico del ácido linoleico conjugado (CLA) se ha evaluado en la vaca l... more Resumen. El efecto antilipogénico del ácido linoleico conjugado (CLA) se ha evaluado en la vaca lechera, hipotetizándose que el CLA afecta la síntesis de novo, pero por no ser la principal ruta de síntesis de ácidos grasos (AG), se desconoce a qué nivel el CLA está inhibiendo dicha síntesis. En las conejas la síntesis de novo es la principal ruta de la síntesis de AG pero se desconoce si el CLA cambia la composición química de su leche o altera el perfil de sus AG, por lo que en este estudio se evaluó el efecto de la suplementación oral del CLA sobre la composición química y el perfil de los AG de la leche de conejas durante los primeros 12 dias de lactancia. Se emplearon 18 conejas Nueva Zelanda asignadas al azar entre el tratamiento 1) grupo control; y el tratamiento 2) suplementación oral de 310 mg CLA/kg de peso metabólico. A partir del día 5 y hasta el 12 postparto, se administró diariamente vía oral el CLA (Tonalin FFA, BASF®) y se obtuvieron muestras individuales de leche obtenidas por ordeña manual. El perfil de los AG se determinó por cromatografía de gases y cuantificados empleando estándares internos. El CLA suplementado no alteró la composición química de la leche de las conejas, pero modificó el perfil de los AG de la grasa de leche reduciendo los AG de cadena larga mono-insaturados y poli-insaturados e incrementando la concentración de C 21:0 y de los isómeros de C 18:2 , CLA cis9,trans11 y CLA trans-10,cis-12.

Journal of Dairy Science, 2011

Consumers are increasingly aware that food components have the potential to influence human healt... more Consumers are increasingly aware that food components have the potential to influence human health maintenance and disease prevention, and dietary fatty acids (FA) have been of special interest. It has been 25 years since the last survey of US milk FA composition, and during this interval substantial changes in dairy rations have occurred, including increased use of total mixed rations and byproduct feeds as well as the routine use of lipid and FA supplements. Furthermore, analytical procedures have improved allowing greater detail in the routine analysis of FA, especially trans FA. Our objective was to survey US milk fat and determine its FA composition. We obtained samples of fluid milk from 56 milk processing plants across the US every 3 mo for one year to capture seasonal and geographical variations. Processing plants were selected based on the criteria that they represented 50% or more of the fluid milk produced in that area. An overall summary of the milk fat analysis indicated that saturated fatty acids comprised 63.7% of total milk FA with palmitic and stearic acids representing the majority (44.1 and 18.3% of total saturated fatty acids, respectively). Unsaturated fatty acids were 33.2% of total milk FA with oleic acid predominating (71.0% of total unsaturated fatty acids). These values are comparable to those of the previous survey in 1984, considering differences in analytical techniques. Trans FA represented 3.2% of total FA, with vaccenic acid being the major trans isomer (46.5% of total trans FA). Cis-9, trans-11 18:2 conjugated linoleic acid represented 0.55% total milk FA, and the major n-3 FA (linolenic acid, 18:3) composed 0.38%. Analyses for seasonal and regional effects indicated statistical differences for some FA, but these were minor from an overall human nutrition perspective as the FA profile for all samples were numerically similar. Overall, the present study provides a valuable database for current FA composition of US fluid milk, and results demonstrate that the milk fatty acid profile is remarkably consistent across geographic regions and seasons from the perspective of human dietary intake of milk fat.

Journal of Dairy Science, Jun 1, 2009

The feeding of conjugated linoleic acid (CLA) supplements to early-lactation dairy cows has been ... more The feeding of conjugated linoleic acid (CLA) supplements to early-lactation dairy cows has been shown to decrease milk fat synthesis and possibly improve reproductive performance. However, previously reported studies used too few animals to clearly establish the effect of CLA on reproduction. Our objective was to combine data from these studies to evaluate the association of CLA with time to first ovulation and time to conception using methods of survival analysis and overall success of pregnancy by logistic regression. A database was compiled of individual animal data (n = 212) from 5 controlled studies in which CLA had been supplemented to early-lactation dairy cows. Survival analysis incorporated both semi-parametric models (Cox proportional hazards) and parametric models (log-normal). The probability of cows becoming pregnant increased in a nonlinear manner as trans-10, cis-12 CLA dose increased, with the optimal dose predicted to be 10.1 g/d. At the optimal dose, the probability of pregnancy was increased by 26% compared with those animals receiving no CLA (probability = 91% and 72%, respectively). Similarly, the log-normal model predicted that time to conception was decreased in a nonlinear manner with increasing trans-10, cis-12 CLA dose. The predicted optimal dose was 10.5 g of trans-10, cis-12 CLA/d and at this dose the median time to conception was decreased by 34 d when compared with those cows not receiving CLA (117 vs. 151 d in milk, respectively). The log-normal model was also the best-fit model for time to first ovulation. Overall, this multi-study analy-sis demonstrated a strong concordance between the nature of the dose response and the predicted optimal dose of trans-10, cis-12 CLA across the 3 reproductive variables evaluated. These results indicate that reproductive performance of dairy cows may be improved by feeding of CLA supplements during early lactation.

British Journal of Nutrition, Mar 1, 2005

The aim of this study was to determine whether dietary supplementation with branched-chain amino ... more The aim of this study was to determine whether dietary supplementation with branched-chain amino acids, and the infusion of insulin and dextrose, would increase milk protein secretion in the sow. The experiment involved sixteen lactating sows fed either a normal lactation diet (162 g/kg crude protein, n 8) or a high-protein diet (230 g/kg crude protein, n 8) supplemented with branched-chain amino acids (valine, isoleucine and leucine). Sows were either infused with insulin and dextrose or not infused at all during mid (day 5-10) and late (day 17-22) lactation in a single reversal design. Blood samples were analysed for glucose, and the dextrose infusion rate was adjusted to maintain the blood glucose level within 15 % of pre-infusion levels. Milk (10•1 v. 11•1 kg/d; P¼0•014) and lactose (628 v. 727 g/d; P¼0•002) yield increased with insulin infusion, whereas milk protein content (5•0 % v. 5•5 %; P¼0•007) was increased in diets supplemented with protein and branched-chain amino acids. Piglet growth was increased by feeding the higher-protein diet (237 v. 273 g/d; P¼0•05) but not significantly increased by insulin infusion (245 v. 265 g/d; P¼0•11). These effects were additive such that the combined treatment resulted in a 24 % (56 g/d; P,0•05) increase in piglet growth rate. These data demonstrate that increasing the dietary protein/branched-chain amino acid content can increase milk protein secretion but not milk yield. The infusion of insulin and dextrose increased milk and milk lactose yields, and tended to increase milk protein yield but not milk protein content. These effects are additive and translate to increased protein yield and piglet growth.

MAMMARY GLAND, MILK BIOSYNTHESIS AND SECRETION | Milk Fat

Elsevier eBooks, 2011

Fat is an important component of milk. Nutritionally, fat is the major energy component of milk a... more Fat is an important component of milk. Nutritionally, fat is the major energy component of milk and accounts for many of the physical properties, manufacturing characteristics, and sensory attributes of dairy products. Economically, fat is important to the value of milk as it directly affects the yield of many manufactured dairy products. Additionally, fat is the major energy cost in milk synthesis and significant feed costs are associated with meeting the energy demand. Finally, recent research on milk fat has included a focus on ‘designing’ milk fat to improve its healthfulness and functional properties.

Biosynthesis and biological activity of rumenic acid: a natural CLA isomer

Elsevier eBooks, 2012

Nutrition Research, Jul 1, 2008

Human breast milk is a complex mixture of organic and inorganic compounds. Some compounds, such a... more Human breast milk is a complex mixture of organic and inorganic compounds. Some compounds, such as conjugated linoleic acid (CLA), come partly from the mother's diet and are produced by the mother's body and secreted into the milk. Although several studies have examined the effect of chronic CLA supplementation on breast milk CLA appearance, little is known about the transfer of food CLA to breast milk over the short term. The objective of this study was to conduct a preliminary analysis of the kinetics of CLA appearance in breast milk over the short term. Seven women expressed breast milk at 4-to 6-hour intervals for 2 days after eating either CLA-enriched (1912 mg CLA) or control (231 mg CLA) cookies. Milk samples were freeze-dried, fatty acid methyl esters were prepared using methanolic-potassium hydroxide (KOH), and CLA isomers were quantified by gas chromatography. Analysis revealed the following: (1) CLA enrichment of total fatty acids in the breast milk for 48 hours post ingestion of the CLA-enriched cookies was 2.9-fold above control; (2) total breast milk CLA content for 48 hours post CLA-enriched cookies ingestion was 46% greater than post CLA-moderate cookies ingestion; (3) after ingestion of the CLA-enriched cookies, breast milk CLA enrichment plateaued between 8 to 28 hours. This preliminary study suggests that breast milk fatty acids are enriched in CLA compared to control within 28 hours after the ingestion of a CLA-rich food product and invites further research on the extent and timing with which breast milk composition reflects dietary CLA content.

Journal of Dairy Science, Aug 1, 2018

Trans-10,cis-12 conjugated linoleic acid (CLA) has been identified as an intermediate of rumen fa... more Trans-10,cis-12 conjugated linoleic acid (CLA) has been identified as an intermediate of rumen fatty acid biohydrogenation that caused milk fat depression (MFD) in the dairy cow. Previous studies in cows experiencing CLA-and diet-induced MFD have identified reduced mammary expression of the master lipogenic regulator sterol response element transcription factor 1 (SREBF1) and many of its dependent genes. To distinguish between primary mechanisms regulating milk fat synthesis and secondary adaptations to the reduction in milk fat, we conducted a time-course experiment. Eleven dairy cows received by abomasal infusion an initial priming dose of 6.25 g of CLA followed by 12.5 g/d delivered in multiple pulses per day for 5 d. Cows were milked 3×/d and mammary biopsies were obtained under basal condition (prebolus control) and 12, 30, and 120 h relative to initiation of CLA infusion. Milk fat concentration and yield decreased progressively reaching a nadir at 69 h (1.82% and 38.2 g/h) and averaged 2.03 ± 0.19% and 42.1 ± 4.10 g/h on the last day of treatment (±standard deviation). Expression of fatty acid synthase (FASN) and lipoprotein lipase (LPL) were decreased at 30 and 120 h compared with control. Expression of SREBF1 and THRSP were also decreased at 30 and 120 h compared with control. Additionally, we failed to observe changes in other factors, including peroxisome proliferator-activated receptor γ and liver x receptor β and milk fat globular membrane proteins, during CLA treatment. However, expression of milk fat globular membrane proteins were decreased after 14 d of diet-induced MFD in samples from a previous experiment, indicating a possible long-term response. The rapid decrease in lipogenic enzymes, SREBF1, and THRSP provide strong support for their transcriptional regulation as a primary mechanism of milk fat depression.

American Journal of Physiology-regulatory Integrative and Comparative Physiology, Dec 1, 2010

The trans 10, cis 12-conjugated linoleic acid (10,12-CLA) isomer reduces adiposity in several ani... more The trans 10, cis 12-conjugated linoleic acid (10,12-CLA) isomer reduces adiposity in several animal models. In the mouse, however, this effect is associated with adipose tissue inflammation, hyperinsulinemia and hepatic lipid accumulation. Moreover, 10,12-CLA was recently shown to promote mammary ductal hyperplasia and ErbB2/Her2-driven mammary cancer in the mouse. Reasons for detrimental effects of 10,12-CLA on the mouse mammary gland could relate to its effect on the mammary fat pad (MFP), which is essential for normal development. Accordingly, we hypothesized that mammary effects of 10,12-CLA were mediated through the MFP in a dose-dependent manner. Female FVB mice were fed 10,12-CLA at doses of 0%, 0.1%, 0.2%, or 0.5% of the diet from day 24 of age, and effects on mammary development and metabolism were measured on day 49. The 0.5% dose reduced ductal elongation and caused premature alveolar budding. These effects were associated with increased expression of inflammatory markers and genes shown to alter epithelial growth (IGF binding protein-5) and alveolar budding (TNF-␣ and receptor of activated NF-B ligand). The 0.5% dose also caused hyperinsulinemia and hepatic lipid accumulation. In contrast, the 0.1% 10,12-CLA dose had no adverse effects on mammary development, metabolic events, and inflammatory responses, but remained effective in decreasing adipose weights and lipogenic gene expression. These results show that a low dose of 10,12-CLA reduces adiposity in the mouse without negative effects on mammary development, inflammation, and metabolism, and suggest that previously reported detrimental effects relate to the use of excessive doses. mammary fat pad; ductal growth; fatty liver; lipogenic gene expression CONJUGATED LINOLEIC ACIDS (CLA) consist of positional and geometric isomers of octadecadienoic fatty acids with a conjugated double bond. They are produced by microbial hydrogenation of polyunsaturated fatty acids in the rumen of cattle, goats, and sheep, and accordingly, they occur in trace amounts in ruminant products (Ͻ0.5% of all fatty acids). Over 70% of CLA found in animal products is accounted for by the cis 9, trans 11 isomer (9,11-CLA) and the rest by a collection of minor isomers that includes t10, c12-CLA (10,12-CLA) (25). CLA can also be produced by chemical methods, such as heat alkaline isomerization of linoleic acid. This produces a mixture of CLA isomers

Domestic Animal Endocrinology, Jul 1, 1991

Insulin-like growth factor I (IGF-I) circulates in serum bound to a number of different binding p... more Insulin-like growth factor I (IGF-I) circulates in serum bound to a number of different binding proteins (BPs). With antibodies currently available, BPs must be dissociated and inactivated or removed from serum prior to measurement of IGF-I by radioimmunoassay (RIA). Serum samples which spanned a 13-fold range in IGF-I concentration were obtained from lactating dairy cows and used to develop conditions for assay of IGF-I with minimal interference from BPs. Removal of BPs from serum by acid-ethanol extraction resulted in interference in the RIA. Therefore, serum was incubated with 0.1 M glycyl-glycine HCI to inactivate BPs as suggested by Underwood et al. . Time, temperature and pH were optimum when serum was incubated for 48 hr at 37 C, pH 3.7. Binding protein inactivation was evaluated by ability of glycyl-glycine incubated serum to reassociate with t25I-IGF-I. In addition, BPs isolated by gel filtration of glycyl-glycine incubated serum were tested for interference in the RIA. The concentration of IGF-I in serum where inactivated BPs were removed by acid gel filtration was compared to corresponding glycyl-glycine incubated serum. There was a 1:1 relationship which intersected at zero indicating that total IGF-I could be measured. Therefore, incubation of serum with glycylglycine is a reliable method for measuring total IGF-I in serum from dairy cows.

Journal of Dairy Science, 2007

The study was designed to test the effects of feeding fish meal (FM) and specific n-3 fatty acids... more The study was designed to test the effects of feeding fish meal (FM) and specific n-3 fatty acids on milk yield and composition, dry matter intake, plasma concentrations of metabolic hormones and metabolites, and liver triglyceride accumulation in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden FM or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Milk yield (48.2, 49.8, 48.6, 53.5, and 52.2 ± 1.0 kg/d, respectively) and dry matter intake (22.7, 22.8, 23.0, 23.8, and 24.7 ± 0.5 kg/d, respectively) differed among diets. Average daily plasma glucose concentration (53.4, 55.3, 51.1, 57.6, and 57.3 ± 1.3 mg/dL, respectively) was also affected by diet, and plasma insulin concentration was increased by 5% FM and 2.3% Ca-FOFA. At 25 and 50 DIM, blood was collected before feeding and hourly for 11 h after feeding. Plasma glucose concentrations in cows during the day were similar among diets at 25 DIM, but differed at 50 DIM (54.6, 54.4, 52.4, 60.5, and 58.3 ± 1.4 mg/dL for 0, 1.25, 2.5, and 5% FM or 2.3% CaFOFA, respectively). Plasma insulin was increased in cows fed 5% FM and 2.3% CaFOFA at 25 DIM and was similar among diets at 50 DIM. Dietary treatments had no significant effect on milk composition, energy balance, or on daily plasma concentrations of nonesterified fatty acids, βhydroxybutyrate, and urea. Plasma aspartate aminotransferase and hepatic triglyceride concentration in cows did not differ among diets at 21 DIM. Results from this experiment demonstrate that dietary supplementation with FM or n-3 polyunsaturated fatty acids in early lactating dairy cows significantly increased milk yield and DMI with no change in milk composition.

Journal of Dairy Science, 2007

The study was designed to test the effects of dietary supplementation with fish meal or specific ... more The study was designed to test the effects of dietary supplementation with fish meal or specific n-3 fatty acids on ovarian activity and uterine responses in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden fish meal (FM) or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Ovarian follicular dynamics were monitored along with plasma concentrations of estradiol and progesterone. Beginning at 23 DIM, cows were induced into a synchronized ovulatory cycle. On d 15 after ovulation (49 DIM), cows were injected with oxytocin and blood samples were collected to monitor uterine release of PGF 2α (measured as 13, 14-dihydro-15-keto PGF 2α ; PGFM). Uterine endometrial biopsies were collected for fatty acid analysis and cyclooxygenase-2 (COX-2) protein measurement. Ovarian follicular activities as well as plasma estradiol and progesterone concentrations were similar across diets. Endometrial fatty acid composition of eicosapentaenoic acid (C20:5, n-3) and docosahexaenoic acid (C22:6, n-3) were increased as much as 3-fold by supplementation with fish meal and CaFOFA. Conjugated linoleic acid (C18:2 cis-9, trans-11) in the endometrium was also increased; conversely, arachidonic acid (C20:4, n-6) percentage was decreased by 5% FM. Plasma PGFM response to oxytocin injection was not different among diets and endometrial COX-2 protein abundance did not differ. Results from this experiment demonstrate that dietary supplementation with fish meal or n-3 fatty acids in early lactating dairy cows significantly increased uterine n-3 fatty acid concentrations, but had no apparent effect on endometrial COX-2 or PGF 2α production in response to oxytocin challenge.

Journal of Dairy Science, Sep 1, 2007

The objective of this study was to evaluate the mechanism of action through which conjugated lino... more The objective of this study was to evaluate the mechanism of action through which conjugated linoleic acid (CLA) beneficially affects reproduction. Lactating Holstein cows (n = 45, 20 ± 1 DIM) were assigned to 1 of 3 treatments: 70 g/d of Ca salts of tallow (control); 63 g/d of lipid-encapsulated CLA providing 7.1 g/d of cis-9, trans-11 CLA and 2.4 g/d of trans-10, cis-12 CLA (CLA 75:25); or 76 g/d of lipid-encapsulated CLA providing 7.1 g/d each of cis-9, trans-11 and trans-10, cis-12 CLA (CLA 50:50). Supplements were top-dressed for 37 d, milk production and DMI were recorded daily, and blood samples were taken 3 times per week. At 30 ± 3 DIM, ovulation was synchronized in all cows with a modified Ovsynch protocol, and on d 15 of the cycle cows received an oxytocin injection; blood samples were obtained frequently to measure 13,14 dihydro, 15-keto PGF 2α . On d 16 of the cycle cows received a PGF 2α injection and ovarian follicular aspiration was performed 54 h later. Follicular fluid was analyzed for fatty acids, progesterone, and estradiol. Endometrial biopsies were taken before and again near the end of the supplementation period for fatty acid analysis. The CLA resulted in decreased milk fat content of 14.1 and 6.1% at wk 5 of treatment of CLA 50:50 and CLA 75:25, respectively. There were no differences in energy balance or plasma nonesterified fatty acids; however, plasma IGF-I was greater in cows supplemented with CLA 50:50. The CLA isomers were not detectable in

Effect of CLA on milk fat synthesis in dairy cows: Comparison of inhibition by methyl esters and free fatty acids, and relationships among studies

Lipids, Apr 1, 2004

CLA is a potent inhibitor of milk fat synthesis, as shown by investigations using mixtures of CLA... more CLA is a potent inhibitor of milk fat synthesis, as shown by investigations using mixtures of CLA isomers in FFA form. However, methyl esters of CLA can be initially formed in commercial synthesis, and their use in a supplement has certain manufacturing and cost advantages. Our objective was to compare abomasal infusion of methyl esters of CLA (ME‐CLA) and FFA of CLA (FFA‐CLA) on milk fat synthesis. Data were also combined with previous investigations to examine broader relationships between trans‐10,cis‐12 CLA and the reduction in milk fat. Three mid‐lactation, rumen‐fistulated Holstein cows were used in a 3×3 Latin square design. Treatments were (i) control, (ii) ME‐CLA, and (iii) FFA‐CLA. The ME‐CLA and FFA‐CLA treatments (4.2 g/d trans‐10,cis‐12 CLA) resulted in a comparable reduction in milk fat yield (38 and 39%, respectively) and pattern of reduction in individual FA. In contrast, milk yield, milk protein, and feed intake were unaltered by CLA treatment. Combining data across studies revealed strong correlations relating the reduction in milk fat yield to abomasal dose of trans‐10,cis‐12 CLA (R2=0.86), milk fat content of trans‐10,cis‐12 CLA (R2=0.93), and milk fat secretion of trans‐10,cis‐12 CLA (R2=0.82). Across studies, transfer efficiency of abomasally infused trans‐10,cis‐12 CLA into milk fat was relatively constant (22%; R2=0.94). Overall, ME‐CLA and FFA‐CLA were equally potent in reducing milk fat, and either form could be used to formulate a dietary supplement that would induce milk fat depression.

Physiological Reviews, Jan 7, 1998

Impressive progress has been made during the past 15 years in our understanding of the biology of... more Impressive progress has been made during the past 15 years in our understanding of the biology of somatotropin (ST) in domestic animals. In part, this progress was sparked by advances in biotechnology that made feasible the production of large quantities of recombinant bovine ST (bST) and porcine ST (pST). The availability of recombinant bST and pST resulted in an exponential increase in investigations that explored their role in growth and lactation biology, as well as evaluated their potential for commercial use. Collectively, these studies established that administration of bST to lactating dairy cows increased milk yield, and treatment of growing pigs with pST markedly stimulated muscle growth and reduced fat deposition. In addition to these ''efficacy'' studies, a substantial number of investigations examined the mechanisms by which ST affects lactation and growth of domestic animals. This review summarizes the diverse physiological effects ST has on growth and lactation and discusses the underlying mechanisms that mediate these effects in domestic animals.

American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2000

Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis. Am. J. Ph... more Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R179-R184, 2000.-Conjugated linoleic acids (CLA) are octadecadienoic fatty acids that have profound effects on lipid metabolism. Our previous work showed that CLA (mixture of isomers) markedly reduced milk fat synthesis. In this study, our objective was to evaluate the effects of specific CLA isomers. Multiparous Holstein cows were used in a 3 ϫ 3 Latin square design, and treatments were 4-day abomasal infusions of 1) skim milk (control), 2) 9,11 CLA supplement, and 3) 10,12 CLA supplement. CLA supplements provided 10 g/day of the specific CLA isomer (cis-9,trans-11 or trans-10,cis-12). Treatments had no effect on intake, milk yield, or milk protein yield. Only the 10,12 CLA supplement affected milk fat, causing a 42 and 44% reduction in milk fat percentage and yield, respectively. Milk fat composition revealed that de novo synthesized fatty acids were extensively reduced. Increases in ratios of C 14:0 to C 14:1 and C 18:0 to C 18:1 indicated the 10,12 CLA supplement also altered ⌬ 9 -desaturase. Treatments had minimal effects on plasma concentrations of glucose, nonesterified fatty acids, insulin, or insulin-like growth factor-I. Overall, results demonstrate that trans-10,cis-12 CLA is the isomer responsible for inhibition of milk fat synthesis. lactation; fatty acids; ruminants CONJUGATED LINOLEIC ACIDS (CLA) are octadecadienoic acids that are found predominately in food products derived from ruminant animals. They have been implicated in a wide range of beneficial effects, including anticarcinogenic, antidiabetic, and immune stimulation (2, 18). CLA have also been shown to reduce body fat and alter nutrient partitioning in growing animals, including mice and pigs . However, all of these biological effects have been observed using dietary supplements that contain a variety of CLA isomers, and effects of specific isomers are unknown. CLA administration also affects lipid synthesis in lactating cows, resulting in marked reductions in milk fat secretion . Several dietary situations, such as high-concentrate, low-fiber diets or increasing in-