David Pacheco | AgResearch Limited (original) (raw)
Papers by David Pacheco
Proceedings of the New Zealand Grassland Association
Enhancing the concentration of water soluble carbohydrate (WSC) in ryegrass by management or bree... more Enhancing the concentration of water soluble carbohydrate (WSC) in ryegrass by management or breeding affects other chemical constituents, which may also contribute to the animal response. A large data set (n=220) of chemical composition of 3 ryegrasses was examined to determine the relationship between elevated WSC and other constituents. Keywords: water soluble carbohydrate, perennial ryegrasses, high sugar grasses, protein, neutral detergent fibre
Proceedings of the New Zealand Grassland Association
New Zealand pastures often contain a higher concentration of nitrogen (N) than required by rumina... more New Zealand pastures often contain a higher concentration of nitrogen (N) than required by ruminants, and this can be exacerbated by application of N fertilisers to boost pasture growth. Excess dietary nitrogen (N) has negative implications for environmental sustainability and animal production, but producers and rural professionals are sometimes unaware of these issues and especially the terminology often used to describe the forms and fate of N. Keywords: nitrogen, ruminant nutrition, protein metabolism
Journal of New Zealand Grasslands
Eighty late-lactation dairy cows were used to examine the effects of allocating a new strip of a ... more Eighty late-lactation dairy cows were used to examine the effects of allocating a new strip of a perennial ryegrass-based sward in the morning (AM) or in the afternoon (PM) on milk fatty acid (FA) and protein profiles. Milk total polyunsaturated FA (PUFA) were greater from cows on AM herbage, whereas total saturated and monounsaturated FA (MUFA) were similar. Time of allocation only affected the milk protein α-casein, which was greater in milk from cows on PM herbage, in turn affecting the casein:whey ratio. Under the current conditions, timing of allocation altered the herbage nutrient supply to cows; a greater concentration of precursor FA in AM herbage resulted in a greater concentration of beneficial FA in milk compared with cows on PM herbage. Quantifying the composition of FA in herbage could potentially aid in the design of grazing strategies to increase precursors of beneficial FA in dairy products. Keywords: fatty acids, milk proteins, herbage composition, time of allocation
Animals
Feeding frequency and feeding level are two important factors affecting rumen fermentation charac... more Feeding frequency and feeding level are two important factors affecting rumen fermentation characteristics, but few studies on these have been conducted on fresh forage. Eight rumen-fistulated sheep were fed either fresh chicory or perennial ryegrass hourly in the first period (d 14 to 21) of the experiment and twice-daily in the second period (d 22 to 27) at 1.3 or 2.2 times the requirement of metabolizable energy for maintenance. When fed hourly, but not twice-daily, rumen fluid pH value was affected by forage species and feeding level. The total concentrations of short-chain fatty acid (SCFA) were similar at both feeding levels when fed chicory hourly, but they were greater at the higher feeding level in comparison with the lower feeding level when fed perennial ryegrass. However, forage species and feeding level did not affect rumen fluid total SCFA concentration when sheep were fed twice-daily. Therefore, rumen fermentation characteristics were affected by forage species, feedi...
Journal of Animal Science
Animal Nutrition, 2016
Research trials with fresh forages often require accurate and precise measurement of digestibilit... more Research trials with fresh forages often require accurate and precise measurement of digestibility and variation in digestion between individuals, and the duration of measurement periods needs to be established to ensure reliable data are obtained. The variation is likely to be greater when freshly harvested feeds are given, such as perennial ryegrass ( L.) and forage rape ( L.), because the nutrient composition changes over time and in response to weather conditions. Daily feed intake and faeces output data from a digestibility trial with these forages were used to calculate the effects of differing lengths of the measurement period and differing numbers of sheep, on the precision of digestibility, with a view towards development of a protocol. Sixteen lambs aged 8 months and weighing 33 kg at the commencement of the trial were fed either perennial ryegrass or forage rape (8/treatment group) over 2 periods with 35 d between measurements. They had been acclimatised to the diets, having grazed them for 42 d prior to 11 days of indoor measurements. The sheep numbers required for a digestibility trial with different combinations of acclimatisation and measurement period lengths were subsequently calculated for 3 levels of imposed precision upon the estimate of mean dry matter (DM) digestibility. It is recommended that if the standard error of the mean for digestibility is equal to or higher than 5 g/kg DM, and if sheep are already used to a fresh perennial ryegrass or forage rape diet, then a minimum of 6 animals are needed and 4 acclimatisation days being fed individually in metabolic crates followed by 7 days of measurement.
Skatole (3-methylindole) is a toxic xenobiotic produced during rumen bacterial degradation of try... more Skatole (3-methylindole) is a toxic xenobiotic produced during rumen bacterial degradation of tryptophan. Skatole contributes to the unique flavour palate known as pastoral flavour (characterised by 'sheepy' or grassy' odours) that differentiates meat and milk products of pasture-fed ruminants from those finished under grain-based production systems. Accumulation in milk and meat fat occurs when skatole absorbed from the reticulorumen exceeds the detoxification capacity of the liver. These conditions arise when ruminants are fed fresh forages with high rumen degradable protein (RDP) content. We hypothesize that under conditions of minimal endogenous skatole production (low dietary RDP) a continuous rumen infusion of skatole will elevate absorption and modify liver metabolism of skatole within 72 h. This hypothesis is supported by a 50% reduction in peripheral plasma skatole concentration between 16 and 72 h of continuous skatole infusion (Deighton et al. 2006). Therefore...
High prolificacy (twins and triplets) is a desirable trait in sheep under intensive management sy... more High prolificacy (twins and triplets) is a desirable trait in sheep under intensive management systems. However, multiple-born lambs have lower birth weights resulting from placental insufficiency, and carryover detrimental effects on lean deposition, feed efficiency, and lifelong performance compared to singletons, suggesting differential nutritional programming in utero. We and others have shown that decreased birth weight in multiple-born lambs is associated with restricted skeletal muscle hypertrophy or myofibre size, but not number, reduced DNA accumulation, reduced MyoD-positive satellite cells (activated satellite cells) and protein synthesis. However, the molecular mechanisms involved remain to be elucidated. The mammalian target of rapamycin (mTOR) signalling pathway is critical both for sensing nutrient availability, fetal myogenesis, activation of myogenic satellite cells and for nutrient-stimulated muscle growth in both monogastrics and ruminants. The downstream targets ...
AgResearch Grasslands, Palmerston North, New Zealand. LEARN Fellow-AgResearch Grasslands. 12 INTA... more AgResearch Grasslands, Palmerston North, New Zealand. LEARN Fellow-AgResearch Grasslands. 12 INTA Balcarce/FCEyN-UNMDP, Argentina. *cfaverin@balcarce.inta.gov.ar 3 Consumo, componentes de la planta y emisiones de metano de ovejas consumiendo raigrás en Nueva Zelanda A data set of 223 daily methane measurements was collated from three respiration calorimetry experiments (n= 24, 20, and 26 animals in experiments 1, 2, and 3, respectively) using sheep fed fresh ryegrass to examine the effects of dry matter intake (DMI, kg/d) and selected plant 44 components on methane production (CH , g/d) and methane yield (CH , g/kg DMI). A further objective was to compare the observed measurements with those obtained using New Zealand's (NZ) greenhouse gas (GHG) Inventory Emission Factors (EF). Selected plant components (% DM; analysed using near infrared reflectance spectroscopy) included ash, crude protein (CP), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), and the WSC/CP, ...
Administration of bovine growth hormone (GH) has been shown to increase milk production in dairy ... more Administration of bovine growth hormone (GH) has been shown to increase milk production in dairy cows by coordinating the metabolism of various organs and tissues, so that nutrients are repartitioned to the mammary gland to support increased requirements for milk synthesis. Some of the targets for GH are adipose tissue, skeletal muscle, liver and the mammary gland. In muscle GH decreases glucose uptake and increases amino acid catabolism efficiency, whilst the liver responds by increasing the rate of basal gluconeogenesis through lypolysis of adipose reserves. We have previously shown that the increase in total milk protein yield following a six day treatment of dairy cows in mid-lactation with GH is associated with a change in protein translation initiation and elongation. However, whether these effects are tissue-specific has not been explored. The objective of this study was to determine if GH administration influences protein translation initiation and elongation in liver and sk...
Animal Feed Science and Technology, 2014
ABSTRACT Published data have shown that in ruminants, methane (CH4) yields (g/kg dry matter [DM] ... more ABSTRACT Published data have shown that in ruminants, methane (CH4) yields (g/kg dry matter [DM] intake) decline as feed intakes increase and, although the reduction has been attributed to a shorter digesta mean retention time (MRT), there are few supporting data. This study was undertaken to determine the association between digesta kinetics and CH4 emissions measured from sheep in respiration chambers fed either fresh white clover (Trifolium repens; WC) or fresh perennial ryegrass (Lolium perenne; RG) (Experiment 1), or RG at several feed intakes (Experiment 2). Measurements included CH4, whole tract apparent DM digestibility (DDM), total tract and rumen MRT (TMRT and RMRT, respectively) of solid and liquid fractions, as well as passage rates. In Experiment 1, eight sheep each with a rumen fistula were fed hourly either WC or RG forages, repeated over two periods (four sheep/diet/period) at about 1.6 times maintenance requirements for metabolisable energy (MEm; 1.12 kg DM/d). Diet did not affect apparent DDM (726 g/kg), CH4 yield (22.3 g/kg DM intake), or TMRT of solid fractions (29.4 h). However, TMRT for the liquid fraction was shorter (P = 0.037) for sheep fed RG (17.4 h) compared with WC (23.0 h), and rumen digesta analyses suggested a larger rumen liquid pool size when RG was fed (6.05 L) compared with WC (3.96 L) (P = 0.041). Experiment 2 involved 30 sheep offered fresh RG twice daily at about 0.8, 1.2, 1.6, 2.0 and 2.5 x MEm. The DDM did not differ greatly across RG intakes (625 to 648 g/kg) but, as RG intake increased (0.49 to 1.34 kg DM/d), there were corresponding reductions (P < 0.001) in CH4 yield (27.0 to 23.9 g/kg DM intake), liquid TMRT (31.4 to 14.2 h), solid TMRT (46.4 h to 24.8 h), liquid RMRT (18.4 to 7.5 h), and solid RMRT (28.4 to 15.8 h). When CH4 yield was plotted against rumen liquid and solid passage rates, the extent of the relationship was best explained (R2) when RG was fed at different intakes in Experiment 2 (0.71 and 0.66 for liquid and solids, respectively). The 2.7-fold increase in feed intake halved RMRT, but intakes affected passage of the rumen liquid fraction to a greater extent than solids. It can be concluded that reductions in CH4 yield from fresh forages fed to sheep are associated with shorter TMRT and RMRT. Understanding the effects of diet, digestion, feed intake, and feeding frequency on methanogenesis requires more knowledge about rumen digesta kinetics, especially relationships between outflow rates of solid and liquid fractions.
Journal of animal science, 2014
The objective of this study was to determine the association between intracellular free AA (FAA) ... more The objective of this study was to determine the association between intracellular free AA (FAA) profiles in skeletal muscle with muscle growth in twin and singleton fetuses in late pregnancy and at weaning, under an ad libitum feeding regime of the dam. Plasma from singleton- (n = 9) and twin-bearing (n = 10) ewes at d 140 of pregnancy and FAA in the semitendinosus muscle (STM) from the corresponding fetuses were studied. At weaning, intracellular STM FAA concentrations were compared between twins at the same age as singletons (Twin(age); n = 17) and at the same weight as singletons (Twin(wt); n = 17) to that of singletons (n = 20). Twin fetuses were 15% lighter (P = 0.03) with a 20% lighter STM (P = 0.02) compared to singletons. Maternal plasma FAA were similar (P ≥ 0.17) between singleton- and twin-bearing ewes. Twin fetuses had greater (P < 0.05) plasma concentrations of glutamine, histidine, and methionine and lower (P < 0.05) concentrations of aspartate, citrulline, glut...
Journal of dairy science, 2012
The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used d... more The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used dairy ration programs to observed values of duodenal flows of crude protein (CP), protein fractions, and essential AA (EAA). The literature was searched and 40 studies, including 154 diets, were used to compare observed values with those predicted by AminoCow (AC), Agricultural Modeling and Training Systems (AMTS), Cornell-Penn-Miner (CPM), and National Research Council 2001 (NRC) models. The models were evaluated based on their ability to predict the mean, their root mean square prediction error (RMSPE), error bias, and adequacy of regression equations for each protein fraction. The models predicted the mean duodenal CP flow within 5%, with more than 90% of the variation due to random disturbance. The models also predicted within 5% the mean microbial CP flow except CPM, which overestimated it by 27%. Only NRC, however, predicted mean rumen-undegraded protein (RUP) flows within 5%, where...
Animal Science, 2005
A database reviewing the metabolism of nitrogen (N) compounds from absorption to milk has been co... more A database reviewing the metabolism of nitrogen (N) compounds from absorption to milk has been compiled from 14 published and unpublished studies (33 treatments) that measured the net flux of N compounds across the splanchnic tissues in dairy cows. Apparent N digestibility averaged 0·65, with this then partitioned between 0·34 excreted in urine and 0·31 secreted as milk.Nitrogen metabolites are absorbed from the lumen of the gut into the portal vein, mainly as free amino acids (AA) and ammonia; these represented 0·58 and 0·57 of digested N, respectively. All of the ammonia absorbed was removed by the liver with, as a result, a net splanchnic flux of zero. Detoxification of ammonia by the liver and catabolism of AA results in production of urea as an end-product. Hepatic ureagenesis is a major cross-road in terms of whole body N exchange, being the equivalent of 0·81 of digested N. Therefore, salvage of a considerable part of this ureagenesis is needed to support milk protein synthes...
Animal Feed Science and Technology, 2012
ABSTRACT Four forage brassicas, kale (Brassica oleracea L. cv. Kestrel), turnip (B. campestris L.... more ABSTRACT Four forage brassicas, kale (Brassica oleracea L. cv. Kestrel), turnip (B. campestris L. cv. Appin), rape (B. napus L. cv. Titan) and swede (B. napus L. cv. Dominion) were compared with perennial ryegrass (Lolium perenne L. cv. mixture of Delish and Banquet) to examine their potential to mitigate CH4 emissions from sheep. Sixty healthy, one-year-old Romney cryptorchids (liveweight 36 ± 1.0 kg) were randomly allocated to 5 groups of 12. The sheep were initially adapted to their diets for 2 wks on paddocks and 1 wk in indoor pens, then fed at 1.5 times their metabolisable energy (ME) maintenance requirement during measurements. Apparent total tract digestibility (n = 5) and ME (n = 5) of brassicas and ryegrass, and rumen fermentation parameters (n = 10) were measured, and CH4 emissions (n = 9) were determined using open circuit respiration chambers. Correlations between nitrate, sulphur, sulphate, glucosinolates and S-methyl cysteine sulphoxide (SMCO) contents of forages and CH4 emissions were determined. Methane emissions/unit feed dry matter intake (g CH4/kg) from sheep were kale 19.8, rape 16.4, swedes 16.9, turnips 20.6 and ryegrass 22.0. Compared with ryegrass, rape and swedes reduced CH4 yield by 23% and 25%, respectively. Total tract digestibilities were higher for brassicas than for ryegrass: 25% higher for DM, organic matter (OM) and crude protein, and 12–16% higher for neutral detergent fibre (aNDF) and acid detergent fibre (ADF). The ME values (MJ/kg DM) were kale 12.7, rape 13.2, swedes 14.1, turnips 12.1 and ryegrass 9.4. Digestibility (P<0.05) and ME (P<0.001) of the forages were correlated to CH4 yield. The correlation coefficients were −0.570 for OM digestibility, −0.505 for NDF digestibility, −0.469 for ADF digestibility and −0.699 for ME. Although the ratio of acetate to propionate in the rumen of sheep fed brassicas was lower than that measured from those fed ryegrass, this ratio was not correlated to CH4 emissions. There were large variations in nitrate, sulphur, sulphate, glucosinolates and SMCO amongst the forage brassicas and ryegrass, but these parameters could not explain reduced CH4 emissions. Feeding brassica forages to sheep reduced emissions/unit DM intake and digestible OM with the reduction being particularly large for forage rape and swedes. Thus these forages may be a viable option for CH4 mitigation from pastoral based sheep production systems. However the mechanisms underlying the reduction need further investigation.This paper is part of the special issue entitled: Plant Bioactive Compounds in Ruminant Agriculture – Impacts and Opportunities, Guest Edited by A.Z.M. Salem and S. López, and Editor for Animal Feed Science and Technology, P.H. Robinson.
… SOCIETY OF ANIMAL …, 1999
Utilisation of amino acids (AA) by the mammary gland of dairy cows has been studied in order to u... more Utilisation of amino acids (AA) by the mammary gland of dairy cows has been studied in order to understand the responses in milk protein production to alterations in nutrient supply. One approach has been the use of balance studies, in which the amount of AA taken up from the blood by the mammary gland is compared with their respective output in milk protein(s). Although it is generally accepted that the free AA pool in blood is the major precursor for milk protein synthesis, there are differences when plasma or whole blood arterio-venous differences (A-V) are used to measure the uptake of AA by the mammary gland. Arterial and venous blood samples were obtained at 2 h intervals from cows fed fresh pasture over two 12-h sampling periods. The samples were subdivided into whole blood (WB) and plasma (P) and analysed for free AA concentrations, which were used to estimate amino acid concentrations in the erythrocyte. There were no significant differences in the A-V calculated from WB or P for the majority of AA. Plasma A-V was significantly higher than WB for threonine (13.9 vs 8.9 nmol/g blood) whilst WB A-V was higher than P for isoleucine (26.9 vs 23.3 nmol/g blood) and tyrosine (11.8 vs 10.3 nmol/g blood). Assuming the differences in A-V between WB and P can be attributed to AA exchange with the red blood cell (RBC), significant (t<0.01) exchange from RBC to the mammary gland occurred for only isoleucine (15% of WB A-V) and tyrosine (14% of WB A-V). These results indicate that plasma AA concentrations are valid measures of the immediate free amino acid pool available for uptake by the mammary gland.
Journal of dairy …, 2009
The underlying molecular mechanisms that control milk yield and milk protein yield in domestic an... more The underlying molecular mechanisms that control milk yield and milk protein yield in domestic animals are not completely understood. In this study, the galactopoietic response to exogenous growth hormone (GH) was used as an experimental model to investigate the role of translation initiation and elongation in the regulation of milk protein synthesis in the mammary gland. A slow-release formula of commercially available GH was administered via a single subcutaneous injection to 4 lactating cows (GH group). A further 4 cows were given a single subcutaneous injection of saline (control group). Changes in mRNA transcript level and protein phosphorylation status of key members of the mammalian target of rapamycin (mTOR) pathway were assessed in mammary gland tissues of these animals using quantitative real-time PCR and Western blotting. The GH treatment enhanced the phosphorylation of ribosomal protein S6 and increased the protein abundance of eukaryotic initiation factor 4E (eIF4E) and eukaryotic elongation factor 2 (eEF2) proteins in the mammary gland of GH-treated animals. These results indicate a link between milk protein synthesis and the regulation of mRNA translation. The GH treatment did not change mRNA abundance of ribosomal protein S6, eIF4E, and eEF2, nor did it change the mRNA (mTOR, eEF2 kinase) or protein abundance of eEF2 kinase. These results demonstrate that GH administration changes mRNA translation initiation and elongation possibly via the mTOR pathway (suggested by the increased levels of ribosomal protein S6 phosphorylation), indicating that the mTOR pathway might be a potential control point in the regulation of milk protein synthesis in the mammary gland.
Journal of dairy …, 2009
The underlying molecular mechanisms that control milk yield and milk protein yield in domestic an... more The underlying molecular mechanisms that control milk yield and milk protein yield in domestic animals are not completely understood. In this study, the galactopoietic response to exogenous growth hormone (GH) was used as an experimental model to investigate the role of translation initiation and elongation in the regulation of milk protein synthesis in the mammary gland. A slow-release formula of commercially available GH was administered via a single subcutaneous injection to 4 lactating cows (GH group). A further 4 cows were given a single subcutaneous injection of saline (control group). Changes in mRNA transcript level and protein phosphorylation status of key members of the mammalian target of rapamycin (mTOR) pathway were assessed in mammary gland tissues of these animals using quantitative real-time PCR and Western blotting. The GH treatment enhanced the phosphorylation of ribosomal protein S6 and increased the protein abundance of eukaryotic initiation factor 4E (eIF4E) and eukaryotic elongation factor 2 (eEF2) proteins in the mammary gland of GH-treated animals. These results indicate a link between milk protein synthesis and the regulation of mRNA translation. The GH treatment did not change mRNA abundance of ribosomal protein S6, eIF4E, and eEF2, nor did it change the mRNA (mTOR, eEF2 kinase) or protein abundance of eEF2 kinase. These results demonstrate that GH administration changes mRNA translation initiation and elongation possibly via the mTOR pathway (suggested by the increased levels of ribosomal protein S6 phosphorylation), indicating that the mTOR pathway might be a potential control point in the regulation of milk protein synthesis in the mammary gland.
Proceedings of the New Zealand Society of Animal Production, Jul 2, 2013
Proceedings of the New Zealand Grassland Association
Enhancing the concentration of water soluble carbohydrate (WSC) in ryegrass by management or bree... more Enhancing the concentration of water soluble carbohydrate (WSC) in ryegrass by management or breeding affects other chemical constituents, which may also contribute to the animal response. A large data set (n=220) of chemical composition of 3 ryegrasses was examined to determine the relationship between elevated WSC and other constituents. Keywords: water soluble carbohydrate, perennial ryegrasses, high sugar grasses, protein, neutral detergent fibre
Proceedings of the New Zealand Grassland Association
New Zealand pastures often contain a higher concentration of nitrogen (N) than required by rumina... more New Zealand pastures often contain a higher concentration of nitrogen (N) than required by ruminants, and this can be exacerbated by application of N fertilisers to boost pasture growth. Excess dietary nitrogen (N) has negative implications for environmental sustainability and animal production, but producers and rural professionals are sometimes unaware of these issues and especially the terminology often used to describe the forms and fate of N. Keywords: nitrogen, ruminant nutrition, protein metabolism
Journal of New Zealand Grasslands
Eighty late-lactation dairy cows were used to examine the effects of allocating a new strip of a ... more Eighty late-lactation dairy cows were used to examine the effects of allocating a new strip of a perennial ryegrass-based sward in the morning (AM) or in the afternoon (PM) on milk fatty acid (FA) and protein profiles. Milk total polyunsaturated FA (PUFA) were greater from cows on AM herbage, whereas total saturated and monounsaturated FA (MUFA) were similar. Time of allocation only affected the milk protein α-casein, which was greater in milk from cows on PM herbage, in turn affecting the casein:whey ratio. Under the current conditions, timing of allocation altered the herbage nutrient supply to cows; a greater concentration of precursor FA in AM herbage resulted in a greater concentration of beneficial FA in milk compared with cows on PM herbage. Quantifying the composition of FA in herbage could potentially aid in the design of grazing strategies to increase precursors of beneficial FA in dairy products. Keywords: fatty acids, milk proteins, herbage composition, time of allocation
Animals
Feeding frequency and feeding level are two important factors affecting rumen fermentation charac... more Feeding frequency and feeding level are two important factors affecting rumen fermentation characteristics, but few studies on these have been conducted on fresh forage. Eight rumen-fistulated sheep were fed either fresh chicory or perennial ryegrass hourly in the first period (d 14 to 21) of the experiment and twice-daily in the second period (d 22 to 27) at 1.3 or 2.2 times the requirement of metabolizable energy for maintenance. When fed hourly, but not twice-daily, rumen fluid pH value was affected by forage species and feeding level. The total concentrations of short-chain fatty acid (SCFA) were similar at both feeding levels when fed chicory hourly, but they were greater at the higher feeding level in comparison with the lower feeding level when fed perennial ryegrass. However, forage species and feeding level did not affect rumen fluid total SCFA concentration when sheep were fed twice-daily. Therefore, rumen fermentation characteristics were affected by forage species, feedi...
Journal of Animal Science
Animal Nutrition, 2016
Research trials with fresh forages often require accurate and precise measurement of digestibilit... more Research trials with fresh forages often require accurate and precise measurement of digestibility and variation in digestion between individuals, and the duration of measurement periods needs to be established to ensure reliable data are obtained. The variation is likely to be greater when freshly harvested feeds are given, such as perennial ryegrass ( L.) and forage rape ( L.), because the nutrient composition changes over time and in response to weather conditions. Daily feed intake and faeces output data from a digestibility trial with these forages were used to calculate the effects of differing lengths of the measurement period and differing numbers of sheep, on the precision of digestibility, with a view towards development of a protocol. Sixteen lambs aged 8 months and weighing 33 kg at the commencement of the trial were fed either perennial ryegrass or forage rape (8/treatment group) over 2 periods with 35 d between measurements. They had been acclimatised to the diets, having grazed them for 42 d prior to 11 days of indoor measurements. The sheep numbers required for a digestibility trial with different combinations of acclimatisation and measurement period lengths were subsequently calculated for 3 levels of imposed precision upon the estimate of mean dry matter (DM) digestibility. It is recommended that if the standard error of the mean for digestibility is equal to or higher than 5 g/kg DM, and if sheep are already used to a fresh perennial ryegrass or forage rape diet, then a minimum of 6 animals are needed and 4 acclimatisation days being fed individually in metabolic crates followed by 7 days of measurement.
Skatole (3-methylindole) is a toxic xenobiotic produced during rumen bacterial degradation of try... more Skatole (3-methylindole) is a toxic xenobiotic produced during rumen bacterial degradation of tryptophan. Skatole contributes to the unique flavour palate known as pastoral flavour (characterised by 'sheepy' or grassy' odours) that differentiates meat and milk products of pasture-fed ruminants from those finished under grain-based production systems. Accumulation in milk and meat fat occurs when skatole absorbed from the reticulorumen exceeds the detoxification capacity of the liver. These conditions arise when ruminants are fed fresh forages with high rumen degradable protein (RDP) content. We hypothesize that under conditions of minimal endogenous skatole production (low dietary RDP) a continuous rumen infusion of skatole will elevate absorption and modify liver metabolism of skatole within 72 h. This hypothesis is supported by a 50% reduction in peripheral plasma skatole concentration between 16 and 72 h of continuous skatole infusion (Deighton et al. 2006). Therefore...
High prolificacy (twins and triplets) is a desirable trait in sheep under intensive management sy... more High prolificacy (twins and triplets) is a desirable trait in sheep under intensive management systems. However, multiple-born lambs have lower birth weights resulting from placental insufficiency, and carryover detrimental effects on lean deposition, feed efficiency, and lifelong performance compared to singletons, suggesting differential nutritional programming in utero. We and others have shown that decreased birth weight in multiple-born lambs is associated with restricted skeletal muscle hypertrophy or myofibre size, but not number, reduced DNA accumulation, reduced MyoD-positive satellite cells (activated satellite cells) and protein synthesis. However, the molecular mechanisms involved remain to be elucidated. The mammalian target of rapamycin (mTOR) signalling pathway is critical both for sensing nutrient availability, fetal myogenesis, activation of myogenic satellite cells and for nutrient-stimulated muscle growth in both monogastrics and ruminants. The downstream targets ...
AgResearch Grasslands, Palmerston North, New Zealand. LEARN Fellow-AgResearch Grasslands. 12 INTA... more AgResearch Grasslands, Palmerston North, New Zealand. LEARN Fellow-AgResearch Grasslands. 12 INTA Balcarce/FCEyN-UNMDP, Argentina. *cfaverin@balcarce.inta.gov.ar 3 Consumo, componentes de la planta y emisiones de metano de ovejas consumiendo raigrás en Nueva Zelanda A data set of 223 daily methane measurements was collated from three respiration calorimetry experiments (n= 24, 20, and 26 animals in experiments 1, 2, and 3, respectively) using sheep fed fresh ryegrass to examine the effects of dry matter intake (DMI, kg/d) and selected plant 44 components on methane production (CH , g/d) and methane yield (CH , g/kg DMI). A further objective was to compare the observed measurements with those obtained using New Zealand's (NZ) greenhouse gas (GHG) Inventory Emission Factors (EF). Selected plant components (% DM; analysed using near infrared reflectance spectroscopy) included ash, crude protein (CP), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), and the WSC/CP, ...
Administration of bovine growth hormone (GH) has been shown to increase milk production in dairy ... more Administration of bovine growth hormone (GH) has been shown to increase milk production in dairy cows by coordinating the metabolism of various organs and tissues, so that nutrients are repartitioned to the mammary gland to support increased requirements for milk synthesis. Some of the targets for GH are adipose tissue, skeletal muscle, liver and the mammary gland. In muscle GH decreases glucose uptake and increases amino acid catabolism efficiency, whilst the liver responds by increasing the rate of basal gluconeogenesis through lypolysis of adipose reserves. We have previously shown that the increase in total milk protein yield following a six day treatment of dairy cows in mid-lactation with GH is associated with a change in protein translation initiation and elongation. However, whether these effects are tissue-specific has not been explored. The objective of this study was to determine if GH administration influences protein translation initiation and elongation in liver and sk...
Animal Feed Science and Technology, 2014
ABSTRACT Published data have shown that in ruminants, methane (CH4) yields (g/kg dry matter [DM] ... more ABSTRACT Published data have shown that in ruminants, methane (CH4) yields (g/kg dry matter [DM] intake) decline as feed intakes increase and, although the reduction has been attributed to a shorter digesta mean retention time (MRT), there are few supporting data. This study was undertaken to determine the association between digesta kinetics and CH4 emissions measured from sheep in respiration chambers fed either fresh white clover (Trifolium repens; WC) or fresh perennial ryegrass (Lolium perenne; RG) (Experiment 1), or RG at several feed intakes (Experiment 2). Measurements included CH4, whole tract apparent DM digestibility (DDM), total tract and rumen MRT (TMRT and RMRT, respectively) of solid and liquid fractions, as well as passage rates. In Experiment 1, eight sheep each with a rumen fistula were fed hourly either WC or RG forages, repeated over two periods (four sheep/diet/period) at about 1.6 times maintenance requirements for metabolisable energy (MEm; 1.12 kg DM/d). Diet did not affect apparent DDM (726 g/kg), CH4 yield (22.3 g/kg DM intake), or TMRT of solid fractions (29.4 h). However, TMRT for the liquid fraction was shorter (P = 0.037) for sheep fed RG (17.4 h) compared with WC (23.0 h), and rumen digesta analyses suggested a larger rumen liquid pool size when RG was fed (6.05 L) compared with WC (3.96 L) (P = 0.041). Experiment 2 involved 30 sheep offered fresh RG twice daily at about 0.8, 1.2, 1.6, 2.0 and 2.5 x MEm. The DDM did not differ greatly across RG intakes (625 to 648 g/kg) but, as RG intake increased (0.49 to 1.34 kg DM/d), there were corresponding reductions (P < 0.001) in CH4 yield (27.0 to 23.9 g/kg DM intake), liquid TMRT (31.4 to 14.2 h), solid TMRT (46.4 h to 24.8 h), liquid RMRT (18.4 to 7.5 h), and solid RMRT (28.4 to 15.8 h). When CH4 yield was plotted against rumen liquid and solid passage rates, the extent of the relationship was best explained (R2) when RG was fed at different intakes in Experiment 2 (0.71 and 0.66 for liquid and solids, respectively). The 2.7-fold increase in feed intake halved RMRT, but intakes affected passage of the rumen liquid fraction to a greater extent than solids. It can be concluded that reductions in CH4 yield from fresh forages fed to sheep are associated with shorter TMRT and RMRT. Understanding the effects of diet, digestion, feed intake, and feeding frequency on methanogenesis requires more knowledge about rumen digesta kinetics, especially relationships between outflow rates of solid and liquid fractions.
Journal of animal science, 2014
The objective of this study was to determine the association between intracellular free AA (FAA) ... more The objective of this study was to determine the association between intracellular free AA (FAA) profiles in skeletal muscle with muscle growth in twin and singleton fetuses in late pregnancy and at weaning, under an ad libitum feeding regime of the dam. Plasma from singleton- (n = 9) and twin-bearing (n = 10) ewes at d 140 of pregnancy and FAA in the semitendinosus muscle (STM) from the corresponding fetuses were studied. At weaning, intracellular STM FAA concentrations were compared between twins at the same age as singletons (Twin(age); n = 17) and at the same weight as singletons (Twin(wt); n = 17) to that of singletons (n = 20). Twin fetuses were 15% lighter (P = 0.03) with a 20% lighter STM (P = 0.02) compared to singletons. Maternal plasma FAA were similar (P ≥ 0.17) between singleton- and twin-bearing ewes. Twin fetuses had greater (P < 0.05) plasma concentrations of glutamine, histidine, and methionine and lower (P < 0.05) concentrations of aspartate, citrulline, glut...
Journal of dairy science, 2012
The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used d... more The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used dairy ration programs to observed values of duodenal flows of crude protein (CP), protein fractions, and essential AA (EAA). The literature was searched and 40 studies, including 154 diets, were used to compare observed values with those predicted by AminoCow (AC), Agricultural Modeling and Training Systems (AMTS), Cornell-Penn-Miner (CPM), and National Research Council 2001 (NRC) models. The models were evaluated based on their ability to predict the mean, their root mean square prediction error (RMSPE), error bias, and adequacy of regression equations for each protein fraction. The models predicted the mean duodenal CP flow within 5%, with more than 90% of the variation due to random disturbance. The models also predicted within 5% the mean microbial CP flow except CPM, which overestimated it by 27%. Only NRC, however, predicted mean rumen-undegraded protein (RUP) flows within 5%, where...
Animal Science, 2005
A database reviewing the metabolism of nitrogen (N) compounds from absorption to milk has been co... more A database reviewing the metabolism of nitrogen (N) compounds from absorption to milk has been compiled from 14 published and unpublished studies (33 treatments) that measured the net flux of N compounds across the splanchnic tissues in dairy cows. Apparent N digestibility averaged 0·65, with this then partitioned between 0·34 excreted in urine and 0·31 secreted as milk.Nitrogen metabolites are absorbed from the lumen of the gut into the portal vein, mainly as free amino acids (AA) and ammonia; these represented 0·58 and 0·57 of digested N, respectively. All of the ammonia absorbed was removed by the liver with, as a result, a net splanchnic flux of zero. Detoxification of ammonia by the liver and catabolism of AA results in production of urea as an end-product. Hepatic ureagenesis is a major cross-road in terms of whole body N exchange, being the equivalent of 0·81 of digested N. Therefore, salvage of a considerable part of this ureagenesis is needed to support milk protein synthes...
Animal Feed Science and Technology, 2012
ABSTRACT Four forage brassicas, kale (Brassica oleracea L. cv. Kestrel), turnip (B. campestris L.... more ABSTRACT Four forage brassicas, kale (Brassica oleracea L. cv. Kestrel), turnip (B. campestris L. cv. Appin), rape (B. napus L. cv. Titan) and swede (B. napus L. cv. Dominion) were compared with perennial ryegrass (Lolium perenne L. cv. mixture of Delish and Banquet) to examine their potential to mitigate CH4 emissions from sheep. Sixty healthy, one-year-old Romney cryptorchids (liveweight 36 ± 1.0 kg) were randomly allocated to 5 groups of 12. The sheep were initially adapted to their diets for 2 wks on paddocks and 1 wk in indoor pens, then fed at 1.5 times their metabolisable energy (ME) maintenance requirement during measurements. Apparent total tract digestibility (n = 5) and ME (n = 5) of brassicas and ryegrass, and rumen fermentation parameters (n = 10) were measured, and CH4 emissions (n = 9) were determined using open circuit respiration chambers. Correlations between nitrate, sulphur, sulphate, glucosinolates and S-methyl cysteine sulphoxide (SMCO) contents of forages and CH4 emissions were determined. Methane emissions/unit feed dry matter intake (g CH4/kg) from sheep were kale 19.8, rape 16.4, swedes 16.9, turnips 20.6 and ryegrass 22.0. Compared with ryegrass, rape and swedes reduced CH4 yield by 23% and 25%, respectively. Total tract digestibilities were higher for brassicas than for ryegrass: 25% higher for DM, organic matter (OM) and crude protein, and 12–16% higher for neutral detergent fibre (aNDF) and acid detergent fibre (ADF). The ME values (MJ/kg DM) were kale 12.7, rape 13.2, swedes 14.1, turnips 12.1 and ryegrass 9.4. Digestibility (P<0.05) and ME (P<0.001) of the forages were correlated to CH4 yield. The correlation coefficients were −0.570 for OM digestibility, −0.505 for NDF digestibility, −0.469 for ADF digestibility and −0.699 for ME. Although the ratio of acetate to propionate in the rumen of sheep fed brassicas was lower than that measured from those fed ryegrass, this ratio was not correlated to CH4 emissions. There were large variations in nitrate, sulphur, sulphate, glucosinolates and SMCO amongst the forage brassicas and ryegrass, but these parameters could not explain reduced CH4 emissions. Feeding brassica forages to sheep reduced emissions/unit DM intake and digestible OM with the reduction being particularly large for forage rape and swedes. Thus these forages may be a viable option for CH4 mitigation from pastoral based sheep production systems. However the mechanisms underlying the reduction need further investigation.This paper is part of the special issue entitled: Plant Bioactive Compounds in Ruminant Agriculture – Impacts and Opportunities, Guest Edited by A.Z.M. Salem and S. López, and Editor for Animal Feed Science and Technology, P.H. Robinson.
… SOCIETY OF ANIMAL …, 1999
Utilisation of amino acids (AA) by the mammary gland of dairy cows has been studied in order to u... more Utilisation of amino acids (AA) by the mammary gland of dairy cows has been studied in order to understand the responses in milk protein production to alterations in nutrient supply. One approach has been the use of balance studies, in which the amount of AA taken up from the blood by the mammary gland is compared with their respective output in milk protein(s). Although it is generally accepted that the free AA pool in blood is the major precursor for milk protein synthesis, there are differences when plasma or whole blood arterio-venous differences (A-V) are used to measure the uptake of AA by the mammary gland. Arterial and venous blood samples were obtained at 2 h intervals from cows fed fresh pasture over two 12-h sampling periods. The samples were subdivided into whole blood (WB) and plasma (P) and analysed for free AA concentrations, which were used to estimate amino acid concentrations in the erythrocyte. There were no significant differences in the A-V calculated from WB or P for the majority of AA. Plasma A-V was significantly higher than WB for threonine (13.9 vs 8.9 nmol/g blood) whilst WB A-V was higher than P for isoleucine (26.9 vs 23.3 nmol/g blood) and tyrosine (11.8 vs 10.3 nmol/g blood). Assuming the differences in A-V between WB and P can be attributed to AA exchange with the red blood cell (RBC), significant (t<0.01) exchange from RBC to the mammary gland occurred for only isoleucine (15% of WB A-V) and tyrosine (14% of WB A-V). These results indicate that plasma AA concentrations are valid measures of the immediate free amino acid pool available for uptake by the mammary gland.
Journal of dairy …, 2009
The underlying molecular mechanisms that control milk yield and milk protein yield in domestic an... more The underlying molecular mechanisms that control milk yield and milk protein yield in domestic animals are not completely understood. In this study, the galactopoietic response to exogenous growth hormone (GH) was used as an experimental model to investigate the role of translation initiation and elongation in the regulation of milk protein synthesis in the mammary gland. A slow-release formula of commercially available GH was administered via a single subcutaneous injection to 4 lactating cows (GH group). A further 4 cows were given a single subcutaneous injection of saline (control group). Changes in mRNA transcript level and protein phosphorylation status of key members of the mammalian target of rapamycin (mTOR) pathway were assessed in mammary gland tissues of these animals using quantitative real-time PCR and Western blotting. The GH treatment enhanced the phosphorylation of ribosomal protein S6 and increased the protein abundance of eukaryotic initiation factor 4E (eIF4E) and eukaryotic elongation factor 2 (eEF2) proteins in the mammary gland of GH-treated animals. These results indicate a link between milk protein synthesis and the regulation of mRNA translation. The GH treatment did not change mRNA abundance of ribosomal protein S6, eIF4E, and eEF2, nor did it change the mRNA (mTOR, eEF2 kinase) or protein abundance of eEF2 kinase. These results demonstrate that GH administration changes mRNA translation initiation and elongation possibly via the mTOR pathway (suggested by the increased levels of ribosomal protein S6 phosphorylation), indicating that the mTOR pathway might be a potential control point in the regulation of milk protein synthesis in the mammary gland.
Journal of dairy …, 2009
The underlying molecular mechanisms that control milk yield and milk protein yield in domestic an... more The underlying molecular mechanisms that control milk yield and milk protein yield in domestic animals are not completely understood. In this study, the galactopoietic response to exogenous growth hormone (GH) was used as an experimental model to investigate the role of translation initiation and elongation in the regulation of milk protein synthesis in the mammary gland. A slow-release formula of commercially available GH was administered via a single subcutaneous injection to 4 lactating cows (GH group). A further 4 cows were given a single subcutaneous injection of saline (control group). Changes in mRNA transcript level and protein phosphorylation status of key members of the mammalian target of rapamycin (mTOR) pathway were assessed in mammary gland tissues of these animals using quantitative real-time PCR and Western blotting. The GH treatment enhanced the phosphorylation of ribosomal protein S6 and increased the protein abundance of eukaryotic initiation factor 4E (eIF4E) and eukaryotic elongation factor 2 (eEF2) proteins in the mammary gland of GH-treated animals. These results indicate a link between milk protein synthesis and the regulation of mRNA translation. The GH treatment did not change mRNA abundance of ribosomal protein S6, eIF4E, and eEF2, nor did it change the mRNA (mTOR, eEF2 kinase) or protein abundance of eEF2 kinase. These results demonstrate that GH administration changes mRNA translation initiation and elongation possibly via the mTOR pathway (suggested by the increased levels of ribosomal protein S6 phosphorylation), indicating that the mTOR pathway might be a potential control point in the regulation of milk protein synthesis in the mammary gland.
Proceedings of the New Zealand Society of Animal Production, Jul 2, 2013