Cesar Meza-herrera - Academia.edu (original) (raw)

Papers by Cesar Meza-herrera

Research paper thumbnail of Taxa de concepção de vacas Holandesas inseminadas artificialmente e afetadas por muco vaginal turvo, sob condições de intenso calor

The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artifici... more The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services), raised under intense heat (mean annual temperature of 22°C), at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses). The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1–21.7%). The conception rate of cows with clean vaginal mucus...

Research paper thumbnail of Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico

Austral journal of veterinary sciences, 2018

The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x La... more The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x Landrace) gilts/ sows in relation to temperature-humidity index (THI) at artificial insemination (AI), season of AI, occurrence of estrus >8 d postweaning, repeated estrus, insemination technique (cervical, CAI or post-cervical, PCAI) and parity. Data included 8851 reproductive records (1771 for gilts and 7080 for sows) from a pig farm in a subtropical zone (THI ranged from 72.9 in January to 81.8 in June). A decrease in pregnancy rate (PR, 89.8 vs 93.0%; P<0.01) and a tendency to decline farrowing rate (FR, 87.9 vs 90.3%; P=0.07) following AI during high THI (>82), compared to AI at <74 THI were observed. The spring and summer season were associated with decreased (P<0.01) PR compared with fall and winter (90.0% vs 93.0%). Likewise, FR decreased in spring and summer compared to fall and winter (88.5% vs. 90.9%). FR was higher (P<0.01) in non-repeat breeders compared with that of repeat-breeders (90.3% vs 76.2%). Litter size increased (P<0.01) from 10.8 ± 3.2 to 11.1 ± 3.1 pigs when the interval from weaning to estrus was >8 d. The insemination technique did not affect PR and FR but the litter size decreased (P<0.05) from 11.3 ± 3.0 to 11.1 ± 2.9 pigs when PCAI was used compared to CAI. This study reaffirms the negative effects of the hot season on reproductive performance of gilts/sows, although thermal stress at AI did not cause foetal losses. Also, there is no advantage in using the PCAI as compared to the CAI in gilts/sows with high numbers of sperm cells per AI.

Research paper thumbnail of PSX-17 Induction of sexual behavior of Dorper rams treated with hCG in northern Mexico

Journal of Animal Science, 2019

To assess whether the application of HCG induces sexual behavior of rams of Dorper rams, a study ... more To assess whether the application of HCG induces sexual behavior of rams of Dorper rams, a study was conducted in northern Mexico (26 º N). Dorper rams (n = 12) were divided into 2 groups (n = 6 each) with homogeneous body weight (78.0 ± 2.5) and body condition score (BCS = 3.3 ± 0.3; 1–5 scale). One group (HCG) received 300 IU of hCG i.m., every 3 d x 1 week, while the other group (CONT) received 0.5 mL of physiological saline solution i.m. every 3 d x 1 week At the end of the treatments, rams were subjected to a sexual behavior test by exposing each male to a female in estrus during 15 min; both the appetitive (ASB, anogenital sniffing, approaching, kicking, vocalizations) and the consummatory (CSB: unsheathing, mount attempt, full mount, mount with unsheathing and mount with ejaculation) sexual behaviors where registered. Data were analyzed with the χ2 test (SYSTAT 12). Both ASB and CSB behaviors favored (P < 0.05) to the HCG rams; ASB 69% vs 30% and CSB 73% vs 27%. Administra...

Research paper thumbnail of Effects of pre-lambing maternal energy supplementation on post-weaning productive performance and thermoregulatory capacity of heat-stressed male lambs

Journal of thermal biology, 2018

Nutritional requirements of sheep during late gestation increase as a consequence of high fetal g... more Nutritional requirements of sheep during late gestation increase as a consequence of high fetal growth, mammary tissue development and colostrum synthesis. While prepartum energy supplementation is a nutritional strategy to improve lamb postnatal performance in thermoneutral environments, this has not been studied under heat stress. This study aimed to evaluate effects of maternal energy supplementation during the last third of pregnancy on post-weaning feedlot performance and thermoregulation capacity of heat-stressed male lambs born from multiple births. Twenty Dorper x Pelibuey entire male lambs with initial body weight of 18.2 ± 0.4 kg, aged 2.7 mo (weaned) and born in multiple pregnancies were used in a 32 d feeding study. Treatments were based in the prenatal origin of the lambs: 1) ewes fed 100 (n = 10, Control) and 2) 125% (n = 10, Supplemented) of metabolizable energy requirements from day 100 of gestation to lambing. Lambs were housed outdoor in individual pens under summe...

Research paper thumbnail of Maternal undernutrition during the pre- and post-conception periods in twin-bearing hairsheep ewes: effects on fetal and placental development at mid-gestation

Tropical animal health and production, 2017

To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental de... more To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental development at mid-gestation, 28 Katahdin × Pelibuey multiparous ewes were blocked by weight and assigned to the following four dietary treatments (n = 7 each): ewes fed 100% (control) or 60% of their nutritional requirements 30 days before mating (UNPre), 50 days after mating (UNPost) or during both periods (UNB). Four twin-bearing ewes were selected per treatment at day 50 post-conception and then slaughtered at day 75 of gestation to analyze their fetuses. Control fetuses were heavier (P < 0.05) than UNPost and UNB fetuses in 14.6 and 9.4%, respectively. Organ weights as percentage of the fetal weight (except for liver) and morphometric measurements (except for abdominal girth) were similar between control and UN fetuses (UNPre, UNPost, and UNB). Placental mass was heavier (P < 0.05) in control ewes than UNB ewes, but not relative to ewes of other treatments. The number of placent...

Research paper thumbnail of Prediction of rectal temperature using non-invasive physiologic variable measurements in hair pregnant ewes subjected to natural conditions of heat stress

Journal of Thermal Biology, 2016

Rectal temperature (RT) is the foremost physiological variable indicating if an animal is sufferi... more Rectal temperature (RT) is the foremost physiological variable indicating if an animal is suffering hyperthermia. However, this variable is traditionally measured by invasive methods, which may compromise animal welfare. Models to predict RT have been developed for growing pigs and lactating dairy cows, but not for pregnant heat-stressed ewes. Our aim was to develop a prediction equation for RT using non-invasive physiological variables in pregnant ewes under heat stress. A total of 192 records of respiratory frequency (RF) and hair coat temperature in various body regions (i.e., head, rump, flank, shoulder, and belly) obtained from 24 Katahdin×Pelibuey pregnant multiparous ewes were collected during the last third of gestation (i.e., d 100 to lambing) with a 15 d sampling interval. Hair coat temperatures were taken using infrared thermal imaging technology. Initially, a Pearson correlation analysis examined the relationship among variables, and then multiple linear regression analysis was used to develop the prediction equations. All predictor variables were positively correlated (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01; r=0.59-0.67) with RT. The adjusted equation which best predicted RT (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01; Radj(2)=56.15%; CV=0.65%) included as predictors RF and head and belly temperatures. Comparison of predicted and observed values for RT indicates a suitable agreement (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01) between them with moderate accuracy (Radj(2)=56.15%) when RT was calculated with the adjusted equation. In general, the final equation does not violate any assumption of multiple regression analysis. The RT in heat-stressed pregnant ewes can be predicted with an adequate accuracy using non-invasive physiologic variables, and the final equation was: RT=35.57+0.004 (RF)+0.067 (heat temperature)+0.028 (belly temperature).

Research paper thumbnail of Reproductive performance of seasonally anovular mixed-bred dairy goats induced to ovulate with a combination of progesterone and eCG or estradiol

Animal science journal = Nihon chikusan Gakkaiho, Jan 21, 2015

Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progeste... more Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progesterone (P4 ) + equine chorionic gonadotropin (eCG), treated with 25 mg progesterone intramuscularly (i.m.) + 250 IU eCG 24 h later; (ii) cronolone + eCG, treated with vaginal sponges - 20 mg cronolone × 7 days + 250 IU eCG at pessary removal; (ii) P4 + estradiol (E2 ), treated with 25 mg progesterone i.m. + 1 mg estradiol 24 h later; (iv) cronolone + E2 , treated with vaginal sponges - 20 mg cronolone × 7 days + 1 mg of estradiol i.m. at pessary removal. Goats were tested for estrus throughout the presence of a buck. Seven days prior and after treatment, an ovarian ultrasonographic scanning was performed to determine ovarian function and structures. An ultrasonographic pregnancy diagnosis was performed on day 30 post-service. In all groups, 100% estrus response was observed within 96 h post-treatment. While ovulation occurred in 100% of P4 + eCG and cronolone + eCG treated goats, the other...

Research paper thumbnail of Effects of summer heat stress on physiological variables, ovulation and progesterone secretion in Pelibuey ewes under natural outdoor conditions in an arid region

Animal Science Journal, 2015

Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects... more Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects of summer thermal stress on physiologic variables, estrous behavior, ovulation and corpus luteum functionality under natural conditions of an arid region. In summer and autumn, daily estrous detection with a ram fitted with an apron and blood sample collections were performed during two natural estrous cycles. An environment of heat stress was detected in summer and thermoneutral in autumn. Rectal temperature and respiratory frequency were greater (P < 0.01) in summer than in autumn during the morning and afternoon. Season did not affect (P > 0.05) live weight, body condition, length of estrous cycle or percentage of ewes in estrous and ovulating. Compared with autumn, serum progesterone concentrations in summer decreased (P < 0.05) between days 8 and 14 of the estrous cycle. It is concluded that under outdoor conditions of arid regions, while estrous and ovulatory activities of Pelibuey ewes were not affected by summer thermal stress, the corpus luteum functionality was decreased.

Research paper thumbnail of Conception rate of artificially inseminated Holstein cows affected by cloudy vaginal mucus, under intense heat conditions

Pesquisa Agropecuária Brasileira, 2015

The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artifici... more The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services), raised under intense heat (mean annual temperature of 22°C), at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses). The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1-21.7%). The conception rate of cows with clean vaginal mucus...

Research paper thumbnail of Effect of dietary energy intake and somatotropin administration after weaning on growth rate and semen characteristics of Granadina goat bucks

Twenty-eight growing Granadina goat bucks, divided into 4 groups of 7, in a 2 × 2 factorial arran... more Twenty-eight growing Granadina goat bucks, divided into 4 groups of 7, in a 2 × 2 factorial arranged design, were used to study the eff ect of post-weaning levels of dietary energy and administration of recombinant bovine somatotropin (rbST) on growth and semen characteristics. Every 14 days, bucks were off ered sustenance at rates of either 1.0 (standard diet, 2.36 Mcal EM kg-1 ; 15% CP) or 1.25 (increased diet, 2.95 Mcal EM kg-1 ; 18% CP) times the requirements for growth energy and protein, for a total of 99 days and in combination with or without subcutaneous administration of 125 mg rbST. Th e average daily gains (ADG) were greater (P < 0.01) in bucks fed the high energy diet (133 ± 25 vs. 111 ± 23 g day-1) and the ADG were greater (P < 0.05) in the bucks treated with rbST than in the untreated bucks (130 ± 28 vs. 114 ± 23 g day-1). Th e percentage of live sperm cells was not diff erent between bucks fed increased diet of NRC recommendations and bucks fed standard diet. Similarly, the sperm output of bucks on the increased diet did not diff er from that of bucks on the standard diet (2282 ± 1137 vs. 1946 ± 529 × 10 6 /mL). Semen volume (0.51 ± 0.29 vs. 0.55 ± 0.28 mL), sperm concentration (2210 ± 1139 vs. 2055 ± 656 × 10 6 /mL), total sperm cells (1233 ± 962 vs. 1014 ± 572 ×x 10 6), and motile sperm cells (67.1 ± 14.5 vs. 60.9 ± 19.3) were not aff ected by rbST. No signifi cant diff erences due to dietary and hormonal treatments were observed in scrotal circumference. Dietary and hormonal treatments had no eff ect on either serum concentration of particular metabolites, except cholesterol. Results from this study indicate that both high energy diets and chronic application of rbST enhanced the growth performance of young Granadina goat bucks; nevertheless, none of these eff ects altered the fi nal scrotal circumference, particular blood metabolites, and sperm output.

Research paper thumbnail of Glutamate supply positively affects serum cholesterol concentrations without increases in total protein and urea around the onset of puberty in goats

Animal Reproduction Science, 2014

Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. ... more Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. Whereas the endocrine and neural systems are activated in response to the metabolic status and the circulating levels of specific blood metabolites, glutamate receptors have been reported at hepatic level. This study evaluated the possible effect of glutamate supplementation upon changes in serum concentrations across time for total protein (TP), urea (UR) and cholesterol (CL) around the onset of puberty in goats. Prepuberal female goats (n = 18) were randomly assigned to: (1) excitatory amino acids group, GLUT, n = 10; 16.52 ± 1.04 kg live weight (LW), 3.4 ± 0.12 body condition score (BCS) receiving an i.v. infusion of 7 mg kg −1 LW of l-glutamate, and (2) Control group, CONT, n = 8; 16.1 ± 1.04 kg LW, 3.1 ± 0.12 BCS. General averages for LW (23.2 ± 0.72 kg), BCS (3.37 ± 0.10 units), serum TP (65.28 ± 2.46 mg dL −1), UR (23.42 ± 0.95 mg dL −1), CL (77.89 ± 1.10 mg dL −1) as well as the serum levels for TP and UR across time did not differ (P > 0.05) between treatments. However, while GLUT positively affected (P < 0.05) both the onset (207 ± 9 vs. 225 ± 12 d) and the percentage (70 vs. 25%) of females showing puberty, a treatment × time interaction effect (P < 0.05) was observed in the GLUT group, with increases in serum cholesterol, coincident with the onset of puberty. Therefore, in peripuberal glutamate supplemented goats, serum cholesterol profile could act as a metabolic modulator for the establishment of puberty, denoting also a potential role of glutamate as modulator of lipid metabolism.

Research paper thumbnail of Buck-induced estrus in grazing goats during increasing photoperiod and under cold stress at 25° N

Veterinarija ir Zootechnika

This study characterizes the goat response to the buck stimulus during the transition from anestr... more This study characterizes the goat response to the buck stimulus during the transition from anestrus to complete sexual function in mixed-breed goat herds maintained on an arid rangeland (25°N). In a first experiment, seasonal incidence of behavioural estrus was recorded by exposure of does to bucks (buck to doe ratio 1:18-1:24; n= 60-96) in February, April, May and June. Signs of estrus were observed in 89, 1, 100 and 88% of goats exposed to bucks during these months, respectively, within a mean ± SD of 5.6 ± 3.8, 8.0 ± 0.0, 9.4 ± 4.9 and 4.7 ± 3.7 days from the initiation of teasing to first standing estrus. In a second experiment, two groups of goats were joined to bucks in January, one group (n= 44) undergoing cold stress (constant drizzling and 8ºC mean daily temperature), the other without rain and mild temperatures (13.6ºC; n= 44). A lower proportion of goats under cold stress, manifested by higher (p<0.01) plasma cortisol levels, showed estrus compared with goats under mil...

Research paper thumbnail of Effect of lactation number, year, and season of initiation of lactation on milk yield of cows hormonally induced into lactation and treated with recombinant bovine somatotropin

Journal of Dairy Science, 2011

Records representing data from 1,500 barren Holstein cows over an 8-yr period from a large commer... more Records representing data from 1,500 barren Holstein cows over an 8-yr period from a large commercial dairy farm in northern Mexico were analyzed to determine the effects of lactation number and season and year of initiation of lactation on milk production of cows induced hormonally into lactation and treated with recombinant bovine somatotropin (rbST) throughout lactation. Peak and 305-d milk yields were also assessed as predictors of total milk yield in cows induced into lactation. A significant quadratic relationship was found between 305-d milk yield and number of lactation [7,607 ± 145 and 9,548 ± 181 kg for first-and ≥6-lactation cows, respectively; mean ± standard error of the mean (SEM)] with the highest production occurring in the fifth lactation. Total milk yields of cows with ≤2 lactations were approximately 4,500 kg less than milk yields of adult cows (the overall average ± standard milk yield was 13,544 ± 5,491 kg per lactation and the average lactation length was 454 ± 154 d). Moreover, 305-d milk production was depressed in cows induced into lactation in spring (8,804 ± 153 kg; mean ± SEM) and summer (8,724 ± 163 kg) than in fall (9,079 ± 151 kg) and winter (9,085 ± 143 kg). Partial regression coefficients for 305-d milk yield and peak milk yield indicated an increment of 157 kg of milk per lactation per 1-kg increase in peak milk yield (r 2 = 0.69). Neither peak milk yield (r 2 = 0.18) nor 305-d milk yield (r 2 = 0.29) was accurate for predicting total milk yield per lactation. Year, parity, and season effects had significant influence on milk yield of cows induced into lactation and treated with rbST throughout lactation, and peak milk yield can assist in the prediction of 305-d milk yield but not total milk yield. This study also showed that hormonal induction of lactation in barren high-yielding cows is a reliable, practical, and affordable technique in countries where rbST treatment and prolonged steroid administration of dairy cows are legally permitted.

Research paper thumbnail of The effect of flushing and stimulus of estrogenized does on reproductive performance of anovulatory-range goats

Tropical Animal Health and Production, 2011

This study was conducted to determine whether flushing or the stimulus of estrogenized goats is n... more This study was conducted to determine whether flushing or the stimulus of estrogenized goats is necessary to achieve a high reproductive response in anestrous goats on rangeland. Does were feed-supplemented on rangeland (flushed, n=20). Other group was exposed to estrogenized does during the mating period (stimulated, n=20). A third group was both supplemented and stimulated (stimulatedflushed, n=20) and other group grazed on rangeland only (control, n=18). More goats in the stimulated and stimulatedflushed groups showed estrus during the first 5 days of joining (45% and 60%, respectively) than the control and flushed groups (11% and 5%, respectively; P<0.05). Flushing did not improve prolificacy and reduced (P<0.05) kidding rates (40% and 35% for the flushed and stimulated-flushed groups, respectively) compared to 67% and 55% for the control and stimulated groups, respectively. This experiment demonstrates potential shortcomings of use of flushing in range goats with inadequate nutrition during gestation.

Research paper thumbnail of Influence of sexually inactive bucks subjected to long photoperiod or testosterone on the induction of estrus in anovulatory goats

Tropical Animal Health and Production, 2011

The objective of this study was to evaluate the efficacy of treating sexually inactive bucks with... more The objective of this study was to evaluate the efficacy of treating sexually inactive bucks with artificial long photoperiod or testosterone on the induction of estrus in anovulatory grazing goats. A total of 91 multiparous mixedbreed anestrous goats were randomly assigned to one of three treatment groups: (1) joining with bucks subjected to 2.5 month of artificial long days (16 h of light/day; n=31), (2) joining with testosterone-treated bucks (n=30), and (3) joining with untreated bucks (control; n=30). There were no differences between the light-treated (100%) and testosterone-treated (93%) bucks in their ability to induce estrus in anovulatory does. On the other hand, none of the goats in contact with control bucks exhibited estrus. The interval from start of mating to estrus was shorter in goats with the light-treated bucks (37.9±4.8 h) compared with does in contact with testosterone-treated bucks (58.3±8.7 h). The overall pregnancy rate in goats joined with light-treated, testosterone-treated and control bucks was 84%, 77% and 0%, respectively, with no difference (P>0.05) between the first two groups. Anogenital sniffing, approaches, mounting attempts, and mounts were highest (P<0.01) in light-treated bucks and lowest in control bucks. It was concluded that testosterone-treated bucks and long-day-treated bucks were equally effective in synchronizing estrus in anovulatory goats and resulted in similar levels of fertility. Given that lighttreated bucks are unviable in communal production systems of goats raised by resource-poor farmers, the sexual arousal of bucks with testosterone is a practical and reliable method to induce ovulation in anovulatory goats in pastoral goat systems in hot environments.

Research paper thumbnail of Estrus induction in anestrous mixed-breed goats using the “female-to-female effect”

Tropical Animal Health and Production, 2012

A trial was conducted during the anestrous period in female goats to determine: (a) whether estru... more A trial was conducted during the anestrous period in female goats to determine: (a) whether estrus can be induced in anestrous goats by administration of equine chorionic gonadotropic hormone (eCG) and PGF 2α under pen conditions and (b) whether these sexually active female goats can elicit sexual arousal in sexually inactive bucks. One hundred and fifteen pluriparous, nonlactating mixed-breed female goats were randomly assigned to one of four treatment groups: (1) administration of a single dose of 240 IU of eCG, 50 μg PGF 2α i.m., and 25 mg progesterone (P 4) (eCG; n030); (2) administration of P 4 and exposure to female goats treated with eCG-PGF 2α (P 4 ; n039); (3) administration of 0.5 ml saline and P 4 (Sal; n023); and (4) P 4 plus exposure to female goats treated with saline (Con; n023). After hormone administration, all goats were put together with adult sexually inactive bucks for 15 days. The percentage of goats in estrus during these 15 days was similar in eCG-treated animals and untreated animals exposed to the eCG animals (97 and 95 %). Pregnancy rate was also similar (63 vs. 64 %) between these two groups. eCG-treated goats exhibited estrus earlier (P<0.05) than the treated goats in contact with the eCG goats. Furthermore, eCG-treated goats had larger litters (1.9±0.2 vs. 1.6±0.1, P<0.05) than the untreated goats in contact with the eCG goats. These results show that fertile estrus can be induced in anestrous female goats by exposing them to female goats induced to estrus with eCG. This female-female interaction triggers the stimulation cycle leading to the sexual arousal of bucks.

Research paper thumbnail of Effect of parity and progesterone priming on induction of reproductive function in Saanen goats by buck exposure

Livestock Science, 2009

The response to the buck effect and the use of progesterone priming was studied in Saanen goats d... more The response to the buck effect and the use of progesterone priming was studied in Saanen goats during the non-breeding season (April and May) in northern Mexico (26°N). Forty goats were assigned randomly in equal numbers (n = 10) to four treatment groups in a 2 × 2 factorial arrangement. Treatment consisted of two dosages of progesterone (P4) (0 or 5 mg) and two categories of goats, nulliparous and multiparous. Both parity groups were exposed to sexually active bucks previously exposed to a long-day photoperiodic scheme (16 h light day − 1). All multiparous goats (20/20) displayed estrous behavior within the first 10 days of buck exposure, while 70% (14/20) of the nulliparous goats showed estrus (P N 0.05). During the first five days of buck exposure, the percentage of unprimed goats in estrus was 70% points lower than the primed goats, although progesterone priming did not affect the occurrence of estrus (90% vs 80%; P N 0.05) after 10 days of buck stimulus. The time to onset of estrus was four days shorter (P b 0.05) in P4-treated goats compared with controls. Pregnancy rate did not differ between primed and unprimed goats (80 vs 60%; P N 0.05), but this variable was higher (P b 0.05) in multiparous than nulliparous goats (95 vs 45%). It was concluded that it is possible to induce fertile estrus in Saanen goats during the non-breeding season in northern Mexico using sexually active bucks. The use of progesterone priming can accelerate the response of goats to the buck stimulus although it was ineffective in improving the pregnancy rate of goats. Additionally, a higher proportion of the multiparous goats got pregnant compared with the nulliparous goats induced to estrus by the buck stimulus.

Research paper thumbnail of Response of sexually inactive French Alpine bucks to the stimulus of goats in oestrus

Livestock Science, 2011

This study was designed to investigate whether sexually inactive French Alpine bucks stimulated w... more This study was designed to investigate whether sexually inactive French Alpine bucks stimulated with goats in oestrus are able to induce oestrus and ovulation in anoestrus goats under intensive conditions at latitude 26°N. Fifty-nine adult anoestrus French Alpine goats were randomly assigned to one of four treatment groups: exposure to stimulated (n = 14) or non-stimulated (n = 15) bucks in March and stimulated (n = 15) or non-stimulated (n = 15) bucks in June. Additionally, the sexual behaviour exhibited by bucks in contact with penned goats was recorded during two consecutive observation sessions lasting 1 h each. The oestrus response was 79 and 100% for goats exposed to stimulated bucks in March and June, respectively, but none of the goats exposed to the non-stimulated bucks entered oestrus in either breeding seasons. Pregnancy rates based on ultrasonographic examination at 50 d postcopulation were lower (P b 0.01) in goats exposed to stimulated bucks in March (50%) compared to goats bred in June (80%). For both breeding seasons, none of the goats exposed to non-stimulated bucks kidded. The interval to oestrus was shorter (68 ± 2 vs. 141 ± 13 h) and more synchronised in goats exposed to stimulated bucks in June than goats exposed to bucks in March. The frequencies of flehmen, nosing, and approaches were higher (P b 0.01) in simulated bucks than non-stimulated bucks. It was concluded that the exposure of sexually inactive bucks to goats in oestrus is an inexpensive, practical and efficient way to elicit sexual activity in bucks, which subsequently triggers breeding activity of anoestrus French Alpine goats.

Research paper thumbnail of Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy

Journal of Thermal Biology, 2013

Research paper thumbnail of Circannual Identification and Quantification of Constitutive Heat Shock Proteins (HSP 70) in Goats

Journal of Applied Animal Research, 2006

... Abstract Meza-Herrera, CA, Martinez, L., Arechiga, C., Bafiuelos, R., Rincon, RM, Urrutia, J.... more ... Abstract Meza-Herrera, CA, Martinez, L., Arechiga, C., Bafiuelos, R., Rincon, RM, Urrutia, J.,Salinas, H. and Mellado, M. 2006. ... The data were analyzed by least square means, with the GLM procedure of SAS for repeated measures across time (Littel et al., 1991; Morris, 1999). ...

Research paper thumbnail of Taxa de concepção de vacas Holandesas inseminadas artificialmente e afetadas por muco vaginal turvo, sob condições de intenso calor

The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artifici... more The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services), raised under intense heat (mean annual temperature of 22°C), at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses). The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1–21.7%). The conception rate of cows with clean vaginal mucus...

Research paper thumbnail of Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico

Austral journal of veterinary sciences, 2018

The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x La... more The objective of this study was to analyse the reproductive performance of hybrid (Yorkshire x Landrace) gilts/ sows in relation to temperature-humidity index (THI) at artificial insemination (AI), season of AI, occurrence of estrus >8 d postweaning, repeated estrus, insemination technique (cervical, CAI or post-cervical, PCAI) and parity. Data included 8851 reproductive records (1771 for gilts and 7080 for sows) from a pig farm in a subtropical zone (THI ranged from 72.9 in January to 81.8 in June). A decrease in pregnancy rate (PR, 89.8 vs 93.0%; P<0.01) and a tendency to decline farrowing rate (FR, 87.9 vs 90.3%; P=0.07) following AI during high THI (>82), compared to AI at <74 THI were observed. The spring and summer season were associated with decreased (P<0.01) PR compared with fall and winter (90.0% vs 93.0%). Likewise, FR decreased in spring and summer compared to fall and winter (88.5% vs. 90.9%). FR was higher (P<0.01) in non-repeat breeders compared with that of repeat-breeders (90.3% vs 76.2%). Litter size increased (P<0.01) from 10.8 ± 3.2 to 11.1 ± 3.1 pigs when the interval from weaning to estrus was >8 d. The insemination technique did not affect PR and FR but the litter size decreased (P<0.05) from 11.3 ± 3.0 to 11.1 ± 2.9 pigs when PCAI was used compared to CAI. This study reaffirms the negative effects of the hot season on reproductive performance of gilts/sows, although thermal stress at AI did not cause foetal losses. Also, there is no advantage in using the PCAI as compared to the CAI in gilts/sows with high numbers of sperm cells per AI.

Research paper thumbnail of PSX-17 Induction of sexual behavior of Dorper rams treated with hCG in northern Mexico

Journal of Animal Science, 2019

To assess whether the application of HCG induces sexual behavior of rams of Dorper rams, a study ... more To assess whether the application of HCG induces sexual behavior of rams of Dorper rams, a study was conducted in northern Mexico (26 º N). Dorper rams (n = 12) were divided into 2 groups (n = 6 each) with homogeneous body weight (78.0 ± 2.5) and body condition score (BCS = 3.3 ± 0.3; 1–5 scale). One group (HCG) received 300 IU of hCG i.m., every 3 d x 1 week, while the other group (CONT) received 0.5 mL of physiological saline solution i.m. every 3 d x 1 week At the end of the treatments, rams were subjected to a sexual behavior test by exposing each male to a female in estrus during 15 min; both the appetitive (ASB, anogenital sniffing, approaching, kicking, vocalizations) and the consummatory (CSB: unsheathing, mount attempt, full mount, mount with unsheathing and mount with ejaculation) sexual behaviors where registered. Data were analyzed with the χ2 test (SYSTAT 12). Both ASB and CSB behaviors favored (P < 0.05) to the HCG rams; ASB 69% vs 30% and CSB 73% vs 27%. Administra...

Research paper thumbnail of Effects of pre-lambing maternal energy supplementation on post-weaning productive performance and thermoregulatory capacity of heat-stressed male lambs

Journal of thermal biology, 2018

Nutritional requirements of sheep during late gestation increase as a consequence of high fetal g... more Nutritional requirements of sheep during late gestation increase as a consequence of high fetal growth, mammary tissue development and colostrum synthesis. While prepartum energy supplementation is a nutritional strategy to improve lamb postnatal performance in thermoneutral environments, this has not been studied under heat stress. This study aimed to evaluate effects of maternal energy supplementation during the last third of pregnancy on post-weaning feedlot performance and thermoregulation capacity of heat-stressed male lambs born from multiple births. Twenty Dorper x Pelibuey entire male lambs with initial body weight of 18.2 ± 0.4 kg, aged 2.7 mo (weaned) and born in multiple pregnancies were used in a 32 d feeding study. Treatments were based in the prenatal origin of the lambs: 1) ewes fed 100 (n = 10, Control) and 2) 125% (n = 10, Supplemented) of metabolizable energy requirements from day 100 of gestation to lambing. Lambs were housed outdoor in individual pens under summe...

Research paper thumbnail of Maternal undernutrition during the pre- and post-conception periods in twin-bearing hairsheep ewes: effects on fetal and placental development at mid-gestation

Tropical animal health and production, 2017

To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental de... more To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental development at mid-gestation, 28 Katahdin × Pelibuey multiparous ewes were blocked by weight and assigned to the following four dietary treatments (n = 7 each): ewes fed 100% (control) or 60% of their nutritional requirements 30 days before mating (UNPre), 50 days after mating (UNPost) or during both periods (UNB). Four twin-bearing ewes were selected per treatment at day 50 post-conception and then slaughtered at day 75 of gestation to analyze their fetuses. Control fetuses were heavier (P < 0.05) than UNPost and UNB fetuses in 14.6 and 9.4%, respectively. Organ weights as percentage of the fetal weight (except for liver) and morphometric measurements (except for abdominal girth) were similar between control and UN fetuses (UNPre, UNPost, and UNB). Placental mass was heavier (P < 0.05) in control ewes than UNB ewes, but not relative to ewes of other treatments. The number of placent...

Research paper thumbnail of Prediction of rectal temperature using non-invasive physiologic variable measurements in hair pregnant ewes subjected to natural conditions of heat stress

Journal of Thermal Biology, 2016

Rectal temperature (RT) is the foremost physiological variable indicating if an animal is sufferi... more Rectal temperature (RT) is the foremost physiological variable indicating if an animal is suffering hyperthermia. However, this variable is traditionally measured by invasive methods, which may compromise animal welfare. Models to predict RT have been developed for growing pigs and lactating dairy cows, but not for pregnant heat-stressed ewes. Our aim was to develop a prediction equation for RT using non-invasive physiological variables in pregnant ewes under heat stress. A total of 192 records of respiratory frequency (RF) and hair coat temperature in various body regions (i.e., head, rump, flank, shoulder, and belly) obtained from 24 Katahdin×Pelibuey pregnant multiparous ewes were collected during the last third of gestation (i.e., d 100 to lambing) with a 15 d sampling interval. Hair coat temperatures were taken using infrared thermal imaging technology. Initially, a Pearson correlation analysis examined the relationship among variables, and then multiple linear regression analysis was used to develop the prediction equations. All predictor variables were positively correlated (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01; r=0.59-0.67) with RT. The adjusted equation which best predicted RT (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01; Radj(2)=56.15%; CV=0.65%) included as predictors RF and head and belly temperatures. Comparison of predicted and observed values for RT indicates a suitable agreement (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01) between them with moderate accuracy (Radj(2)=56.15%) when RT was calculated with the adjusted equation. In general, the final equation does not violate any assumption of multiple regression analysis. The RT in heat-stressed pregnant ewes can be predicted with an adequate accuracy using non-invasive physiologic variables, and the final equation was: RT=35.57+0.004 (RF)+0.067 (heat temperature)+0.028 (belly temperature).

Research paper thumbnail of Reproductive performance of seasonally anovular mixed-bred dairy goats induced to ovulate with a combination of progesterone and eCG or estradiol

Animal science journal = Nihon chikusan Gakkaiho, Jan 21, 2015

Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progeste... more Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progesterone (P4 ) + equine chorionic gonadotropin (eCG), treated with 25 mg progesterone intramuscularly (i.m.) + 250 IU eCG 24 h later; (ii) cronolone + eCG, treated with vaginal sponges - 20 mg cronolone × 7 days + 250 IU eCG at pessary removal; (ii) P4 + estradiol (E2 ), treated with 25 mg progesterone i.m. + 1 mg estradiol 24 h later; (iv) cronolone + E2 , treated with vaginal sponges - 20 mg cronolone × 7 days + 1 mg of estradiol i.m. at pessary removal. Goats were tested for estrus throughout the presence of a buck. Seven days prior and after treatment, an ovarian ultrasonographic scanning was performed to determine ovarian function and structures. An ultrasonographic pregnancy diagnosis was performed on day 30 post-service. In all groups, 100% estrus response was observed within 96 h post-treatment. While ovulation occurred in 100% of P4 + eCG and cronolone + eCG treated goats, the other...

Research paper thumbnail of Effects of summer heat stress on physiological variables, ovulation and progesterone secretion in Pelibuey ewes under natural outdoor conditions in an arid region

Animal Science Journal, 2015

Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects... more Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects of summer thermal stress on physiologic variables, estrous behavior, ovulation and corpus luteum functionality under natural conditions of an arid region. In summer and autumn, daily estrous detection with a ram fitted with an apron and blood sample collections were performed during two natural estrous cycles. An environment of heat stress was detected in summer and thermoneutral in autumn. Rectal temperature and respiratory frequency were greater (P < 0.01) in summer than in autumn during the morning and afternoon. Season did not affect (P > 0.05) live weight, body condition, length of estrous cycle or percentage of ewes in estrous and ovulating. Compared with autumn, serum progesterone concentrations in summer decreased (P < 0.05) between days 8 and 14 of the estrous cycle. It is concluded that under outdoor conditions of arid regions, while estrous and ovulatory activities of Pelibuey ewes were not affected by summer thermal stress, the corpus luteum functionality was decreased.

Research paper thumbnail of Conception rate of artificially inseminated Holstein cows affected by cloudy vaginal mucus, under intense heat conditions

Pesquisa Agropecuária Brasileira, 2015

The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artifici... more The objective of this work was to obtain prevalence estimates of cloudy vaginal mucus in artificially inseminated Holstein cows raised under intense heat, in order to assess the effect of meteorological conditions on its occurrence during estrus and to determine its effect on conception rate. In a first study, an association was established between the occurrence of cloudy vaginal mucus during estrus and the conception rate of inseminated cows (18,620 services), raised under intense heat (mean annual temperature of 22°C), at highly technified farms, in the arid region of northern Mexico. In a second study, data from these large dairy operations were used to assess the effect of meteorological conditions throughout the year on the occurrence of cloudy vaginal mucus during artificial insemination (76,899 estruses). The overall rate of estruses with cloudy vaginal mucus was 21.4% (16,470/76,899; 95% confidence interval = 21.1-21.7%). The conception rate of cows with clean vaginal mucus...

Research paper thumbnail of Effect of dietary energy intake and somatotropin administration after weaning on growth rate and semen characteristics of Granadina goat bucks

Twenty-eight growing Granadina goat bucks, divided into 4 groups of 7, in a 2 × 2 factorial arran... more Twenty-eight growing Granadina goat bucks, divided into 4 groups of 7, in a 2 × 2 factorial arranged design, were used to study the eff ect of post-weaning levels of dietary energy and administration of recombinant bovine somatotropin (rbST) on growth and semen characteristics. Every 14 days, bucks were off ered sustenance at rates of either 1.0 (standard diet, 2.36 Mcal EM kg-1 ; 15% CP) or 1.25 (increased diet, 2.95 Mcal EM kg-1 ; 18% CP) times the requirements for growth energy and protein, for a total of 99 days and in combination with or without subcutaneous administration of 125 mg rbST. Th e average daily gains (ADG) were greater (P < 0.01) in bucks fed the high energy diet (133 ± 25 vs. 111 ± 23 g day-1) and the ADG were greater (P < 0.05) in the bucks treated with rbST than in the untreated bucks (130 ± 28 vs. 114 ± 23 g day-1). Th e percentage of live sperm cells was not diff erent between bucks fed increased diet of NRC recommendations and bucks fed standard diet. Similarly, the sperm output of bucks on the increased diet did not diff er from that of bucks on the standard diet (2282 ± 1137 vs. 1946 ± 529 × 10 6 /mL). Semen volume (0.51 ± 0.29 vs. 0.55 ± 0.28 mL), sperm concentration (2210 ± 1139 vs. 2055 ± 656 × 10 6 /mL), total sperm cells (1233 ± 962 vs. 1014 ± 572 ×x 10 6), and motile sperm cells (67.1 ± 14.5 vs. 60.9 ± 19.3) were not aff ected by rbST. No signifi cant diff erences due to dietary and hormonal treatments were observed in scrotal circumference. Dietary and hormonal treatments had no eff ect on either serum concentration of particular metabolites, except cholesterol. Results from this study indicate that both high energy diets and chronic application of rbST enhanced the growth performance of young Granadina goat bucks; nevertheless, none of these eff ects altered the fi nal scrotal circumference, particular blood metabolites, and sperm output.

Research paper thumbnail of Glutamate supply positively affects serum cholesterol concentrations without increases in total protein and urea around the onset of puberty in goats

Animal Reproduction Science, 2014

Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. ... more Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. Whereas the endocrine and neural systems are activated in response to the metabolic status and the circulating levels of specific blood metabolites, glutamate receptors have been reported at hepatic level. This study evaluated the possible effect of glutamate supplementation upon changes in serum concentrations across time for total protein (TP), urea (UR) and cholesterol (CL) around the onset of puberty in goats. Prepuberal female goats (n = 18) were randomly assigned to: (1) excitatory amino acids group, GLUT, n = 10; 16.52 ± 1.04 kg live weight (LW), 3.4 ± 0.12 body condition score (BCS) receiving an i.v. infusion of 7 mg kg −1 LW of l-glutamate, and (2) Control group, CONT, n = 8; 16.1 ± 1.04 kg LW, 3.1 ± 0.12 BCS. General averages for LW (23.2 ± 0.72 kg), BCS (3.37 ± 0.10 units), serum TP (65.28 ± 2.46 mg dL −1), UR (23.42 ± 0.95 mg dL −1), CL (77.89 ± 1.10 mg dL −1) as well as the serum levels for TP and UR across time did not differ (P > 0.05) between treatments. However, while GLUT positively affected (P < 0.05) both the onset (207 ± 9 vs. 225 ± 12 d) and the percentage (70 vs. 25%) of females showing puberty, a treatment × time interaction effect (P < 0.05) was observed in the GLUT group, with increases in serum cholesterol, coincident with the onset of puberty. Therefore, in peripuberal glutamate supplemented goats, serum cholesterol profile could act as a metabolic modulator for the establishment of puberty, denoting also a potential role of glutamate as modulator of lipid metabolism.

Research paper thumbnail of Buck-induced estrus in grazing goats during increasing photoperiod and under cold stress at 25° N

Veterinarija ir Zootechnika

This study characterizes the goat response to the buck stimulus during the transition from anestr... more This study characterizes the goat response to the buck stimulus during the transition from anestrus to complete sexual function in mixed-breed goat herds maintained on an arid rangeland (25°N). In a first experiment, seasonal incidence of behavioural estrus was recorded by exposure of does to bucks (buck to doe ratio 1:18-1:24; n= 60-96) in February, April, May and June. Signs of estrus were observed in 89, 1, 100 and 88% of goats exposed to bucks during these months, respectively, within a mean ± SD of 5.6 ± 3.8, 8.0 ± 0.0, 9.4 ± 4.9 and 4.7 ± 3.7 days from the initiation of teasing to first standing estrus. In a second experiment, two groups of goats were joined to bucks in January, one group (n= 44) undergoing cold stress (constant drizzling and 8ºC mean daily temperature), the other without rain and mild temperatures (13.6ºC; n= 44). A lower proportion of goats under cold stress, manifested by higher (p<0.01) plasma cortisol levels, showed estrus compared with goats under mil...

Research paper thumbnail of Effect of lactation number, year, and season of initiation of lactation on milk yield of cows hormonally induced into lactation and treated with recombinant bovine somatotropin

Journal of Dairy Science, 2011

Records representing data from 1,500 barren Holstein cows over an 8-yr period from a large commer... more Records representing data from 1,500 barren Holstein cows over an 8-yr period from a large commercial dairy farm in northern Mexico were analyzed to determine the effects of lactation number and season and year of initiation of lactation on milk production of cows induced hormonally into lactation and treated with recombinant bovine somatotropin (rbST) throughout lactation. Peak and 305-d milk yields were also assessed as predictors of total milk yield in cows induced into lactation. A significant quadratic relationship was found between 305-d milk yield and number of lactation [7,607 ± 145 and 9,548 ± 181 kg for first-and ≥6-lactation cows, respectively; mean ± standard error of the mean (SEM)] with the highest production occurring in the fifth lactation. Total milk yields of cows with ≤2 lactations were approximately 4,500 kg less than milk yields of adult cows (the overall average ± standard milk yield was 13,544 ± 5,491 kg per lactation and the average lactation length was 454 ± 154 d). Moreover, 305-d milk production was depressed in cows induced into lactation in spring (8,804 ± 153 kg; mean ± SEM) and summer (8,724 ± 163 kg) than in fall (9,079 ± 151 kg) and winter (9,085 ± 143 kg). Partial regression coefficients for 305-d milk yield and peak milk yield indicated an increment of 157 kg of milk per lactation per 1-kg increase in peak milk yield (r 2 = 0.69). Neither peak milk yield (r 2 = 0.18) nor 305-d milk yield (r 2 = 0.29) was accurate for predicting total milk yield per lactation. Year, parity, and season effects had significant influence on milk yield of cows induced into lactation and treated with rbST throughout lactation, and peak milk yield can assist in the prediction of 305-d milk yield but not total milk yield. This study also showed that hormonal induction of lactation in barren high-yielding cows is a reliable, practical, and affordable technique in countries where rbST treatment and prolonged steroid administration of dairy cows are legally permitted.

Research paper thumbnail of The effect of flushing and stimulus of estrogenized does on reproductive performance of anovulatory-range goats

Tropical Animal Health and Production, 2011

This study was conducted to determine whether flushing or the stimulus of estrogenized goats is n... more This study was conducted to determine whether flushing or the stimulus of estrogenized goats is necessary to achieve a high reproductive response in anestrous goats on rangeland. Does were feed-supplemented on rangeland (flushed, n=20). Other group was exposed to estrogenized does during the mating period (stimulated, n=20). A third group was both supplemented and stimulated (stimulatedflushed, n=20) and other group grazed on rangeland only (control, n=18). More goats in the stimulated and stimulatedflushed groups showed estrus during the first 5 days of joining (45% and 60%, respectively) than the control and flushed groups (11% and 5%, respectively; P<0.05). Flushing did not improve prolificacy and reduced (P<0.05) kidding rates (40% and 35% for the flushed and stimulated-flushed groups, respectively) compared to 67% and 55% for the control and stimulated groups, respectively. This experiment demonstrates potential shortcomings of use of flushing in range goats with inadequate nutrition during gestation.

Research paper thumbnail of Influence of sexually inactive bucks subjected to long photoperiod or testosterone on the induction of estrus in anovulatory goats

Tropical Animal Health and Production, 2011

The objective of this study was to evaluate the efficacy of treating sexually inactive bucks with... more The objective of this study was to evaluate the efficacy of treating sexually inactive bucks with artificial long photoperiod or testosterone on the induction of estrus in anovulatory grazing goats. A total of 91 multiparous mixedbreed anestrous goats were randomly assigned to one of three treatment groups: (1) joining with bucks subjected to 2.5 month of artificial long days (16 h of light/day; n=31), (2) joining with testosterone-treated bucks (n=30), and (3) joining with untreated bucks (control; n=30). There were no differences between the light-treated (100%) and testosterone-treated (93%) bucks in their ability to induce estrus in anovulatory does. On the other hand, none of the goats in contact with control bucks exhibited estrus. The interval from start of mating to estrus was shorter in goats with the light-treated bucks (37.9±4.8 h) compared with does in contact with testosterone-treated bucks (58.3±8.7 h). The overall pregnancy rate in goats joined with light-treated, testosterone-treated and control bucks was 84%, 77% and 0%, respectively, with no difference (P>0.05) between the first two groups. Anogenital sniffing, approaches, mounting attempts, and mounts were highest (P<0.01) in light-treated bucks and lowest in control bucks. It was concluded that testosterone-treated bucks and long-day-treated bucks were equally effective in synchronizing estrus in anovulatory goats and resulted in similar levels of fertility. Given that lighttreated bucks are unviable in communal production systems of goats raised by resource-poor farmers, the sexual arousal of bucks with testosterone is a practical and reliable method to induce ovulation in anovulatory goats in pastoral goat systems in hot environments.

Research paper thumbnail of Estrus induction in anestrous mixed-breed goats using the “female-to-female effect”

Tropical Animal Health and Production, 2012

A trial was conducted during the anestrous period in female goats to determine: (a) whether estru... more A trial was conducted during the anestrous period in female goats to determine: (a) whether estrus can be induced in anestrous goats by administration of equine chorionic gonadotropic hormone (eCG) and PGF 2α under pen conditions and (b) whether these sexually active female goats can elicit sexual arousal in sexually inactive bucks. One hundred and fifteen pluriparous, nonlactating mixed-breed female goats were randomly assigned to one of four treatment groups: (1) administration of a single dose of 240 IU of eCG, 50 μg PGF 2α i.m., and 25 mg progesterone (P 4) (eCG; n030); (2) administration of P 4 and exposure to female goats treated with eCG-PGF 2α (P 4 ; n039); (3) administration of 0.5 ml saline and P 4 (Sal; n023); and (4) P 4 plus exposure to female goats treated with saline (Con; n023). After hormone administration, all goats were put together with adult sexually inactive bucks for 15 days. The percentage of goats in estrus during these 15 days was similar in eCG-treated animals and untreated animals exposed to the eCG animals (97 and 95 %). Pregnancy rate was also similar (63 vs. 64 %) between these two groups. eCG-treated goats exhibited estrus earlier (P<0.05) than the treated goats in contact with the eCG goats. Furthermore, eCG-treated goats had larger litters (1.9±0.2 vs. 1.6±0.1, P<0.05) than the untreated goats in contact with the eCG goats. These results show that fertile estrus can be induced in anestrous female goats by exposing them to female goats induced to estrus with eCG. This female-female interaction triggers the stimulation cycle leading to the sexual arousal of bucks.

Research paper thumbnail of Effect of parity and progesterone priming on induction of reproductive function in Saanen goats by buck exposure

Livestock Science, 2009

The response to the buck effect and the use of progesterone priming was studied in Saanen goats d... more The response to the buck effect and the use of progesterone priming was studied in Saanen goats during the non-breeding season (April and May) in northern Mexico (26°N). Forty goats were assigned randomly in equal numbers (n = 10) to four treatment groups in a 2 × 2 factorial arrangement. Treatment consisted of two dosages of progesterone (P4) (0 or 5 mg) and two categories of goats, nulliparous and multiparous. Both parity groups were exposed to sexually active bucks previously exposed to a long-day photoperiodic scheme (16 h light day − 1). All multiparous goats (20/20) displayed estrous behavior within the first 10 days of buck exposure, while 70% (14/20) of the nulliparous goats showed estrus (P N 0.05). During the first five days of buck exposure, the percentage of unprimed goats in estrus was 70% points lower than the primed goats, although progesterone priming did not affect the occurrence of estrus (90% vs 80%; P N 0.05) after 10 days of buck stimulus. The time to onset of estrus was four days shorter (P b 0.05) in P4-treated goats compared with controls. Pregnancy rate did not differ between primed and unprimed goats (80 vs 60%; P N 0.05), but this variable was higher (P b 0.05) in multiparous than nulliparous goats (95 vs 45%). It was concluded that it is possible to induce fertile estrus in Saanen goats during the non-breeding season in northern Mexico using sexually active bucks. The use of progesterone priming can accelerate the response of goats to the buck stimulus although it was ineffective in improving the pregnancy rate of goats. Additionally, a higher proportion of the multiparous goats got pregnant compared with the nulliparous goats induced to estrus by the buck stimulus.

Research paper thumbnail of Response of sexually inactive French Alpine bucks to the stimulus of goats in oestrus

Livestock Science, 2011

This study was designed to investigate whether sexually inactive French Alpine bucks stimulated w... more This study was designed to investigate whether sexually inactive French Alpine bucks stimulated with goats in oestrus are able to induce oestrus and ovulation in anoestrus goats under intensive conditions at latitude 26°N. Fifty-nine adult anoestrus French Alpine goats were randomly assigned to one of four treatment groups: exposure to stimulated (n = 14) or non-stimulated (n = 15) bucks in March and stimulated (n = 15) or non-stimulated (n = 15) bucks in June. Additionally, the sexual behaviour exhibited by bucks in contact with penned goats was recorded during two consecutive observation sessions lasting 1 h each. The oestrus response was 79 and 100% for goats exposed to stimulated bucks in March and June, respectively, but none of the goats exposed to the non-stimulated bucks entered oestrus in either breeding seasons. Pregnancy rates based on ultrasonographic examination at 50 d postcopulation were lower (P b 0.01) in goats exposed to stimulated bucks in March (50%) compared to goats bred in June (80%). For both breeding seasons, none of the goats exposed to non-stimulated bucks kidded. The interval to oestrus was shorter (68 ± 2 vs. 141 ± 13 h) and more synchronised in goats exposed to stimulated bucks in June than goats exposed to bucks in March. The frequencies of flehmen, nosing, and approaches were higher (P b 0.01) in simulated bucks than non-stimulated bucks. It was concluded that the exposure of sexually inactive bucks to goats in oestrus is an inexpensive, practical and efficient way to elicit sexual activity in bucks, which subsequently triggers breeding activity of anoestrus French Alpine goats.

Research paper thumbnail of Thermoregulation of nutrient-restricted hair ewes subjected to heat stress during late pregnancy

Journal of Thermal Biology, 2013

Research paper thumbnail of Circannual Identification and Quantification of Constitutive Heat Shock Proteins (HSP 70) in Goats

Journal of Applied Animal Research, 2006

... Abstract Meza-Herrera, CA, Martinez, L., Arechiga, C., Bafiuelos, R., Rincon, RM, Urrutia, J.... more ... Abstract Meza-Herrera, CA, Martinez, L., Arechiga, C., Bafiuelos, R., Rincon, RM, Urrutia, J.,Salinas, H. and Mellado, M. 2006. ... The data were analyzed by least square means, with the GLM procedure of SAS for repeated measures across time (Littel et al., 1991; Morris, 1999). ...