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 groups only depicted 50% ovulatory activity (P < 0.05). Pregnancy rate was higher (P <0.05) in the P4 + eCG and cronolone + eCG groups (88 and 100%, respectively), compared with 38% in P4 + E2 and cronolone + E2 groups. The best treatments were those in which eCG was applied. The P4 + eCG treatment was a pessary-free, cheaper and effective protocol to induce ovulation in goats during the seasonal anovulatory period.

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 mixed-breed 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 light-treated 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.

No abstract

The aim of the present study was to use a non-linear regression approach to investigate the relationship between litter birthweight and litter size of five breeds of goat under intensive conditions in a hot arid environment. Litter-size and litter-weight data on 20 117 kids from 13 685 litters representing five breeds, namely Saanen, Toggenburg, French Alpine, Anglo-Nubian and Granadina, were compared to evaluate this relationship. Regardless of breed, birthweight for kids born as twins, triplets and quadruplets was, on average, 92%, 87% and 83%, respectively, of that of singleton kids; litter size accounted for 81% of the variation in litter weight. The coefficient of the power regression differed (P < 0.01) among breeds, with similar slopes for French Alpine, Toggenburg and Saanen goats and a smaller litter-weight increase for every additional fetus in Anglo-Nubian and Granadina goats than in other breeds of goat. These results support the hypothesis that, regardless of parity, litter weight in dairy and Granadina goats increases at a reduced rate with increases in litter size, although the rate of change with the increasing number of fetuses was moderate, as indicated by a power regression of the form y = axb between these variables across age categories and breeds of goat.

No abstract

The potential effect of intravenous administration of glutamate on the ovarian activity and the LH secretion pattern, considering the anestrous yearling goat as an animal model, were assessed. In late April, yearling goats (n = 20) were randomly assigned to either (1) Glutamate supplemented (GLUT; n = 10, Live Weight (LW) = 29.6 ± 1.02 kg, Body Condition (BCS) = 3.4 ± 0.2 units; i.v. supplemented with 7 mg GLUT kg−1 LW) or (2) Non-supplemented (CONT; n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2 units; i.v. saline). The oats were estrus-synchronized; blood sampling (6 h × 15 min) was carried out for LH quantification. Response variables included pulsatility (PULSE), time to first pulse (TTFP), amplitude (AMPL), nadir (NAD), and area under the curve (AUC) of LH. Ovaries were ultra-sonographically scanned to assess ovulation rate (OR), number of antral follicles (AF), and total ovarian activity (TOA = OR + AF). LH-PULSE was quantified with the Munro algorithm; significant treatment x time interactions were evaluated across time. The variables LW and BCS did not differ (p > 0.05) between the experimental groups. Nevertheless, OR (1.77 vs. 0.87 ± 0.20 units), TOA (4.11 vs. 1.87 ± 0.47 units) and LH-PULSE (5.0 vs. 2.2 pulses 6 h-1) favored (p < 0.05) to the GLUT group. Our results reveal that targeted glutamate supplementation, the main central nervous system neurotransmitter, arose as an interesting strategy to enhance the hypothalamic–hypophyseal–ovarian response considering the anestrous-yearling goat as an animal model, with thought-provoking while promising translational applications.

This study evaluated the effects of peripartum feed supplementation on doe and kid BW and BCS, milk yield and composition, serum metabolites, and maternal-neonatal behavior under rangeland conditions in northern Mexico. Adult does ( = 23) were randomly assigned to 3 nutritional plane groups: 1) goats supplemented (500 g of concentrate [18% CP/kg DM, 2.7 Mcal/kg DM, and 2% salt]) from 15 d prepartum to 7 d postpartum (G15; = 8), 2) the same supplementation as G15 but from 35 d before until 7 d after kidding (G35; = 8), and 3) nonsupplemented does (GC; = 7). Supplemented goats differed from GC goats in BW (48 ± 1.8, 46.1 ± 2.5, and 44.9 ± 2.3 kg; < 0.05), milk yield (1.8 ± 0.1, 1.9 ± 0.2, and 1.2 ± 0.1 kg at d 15 postpartum; < 0.01), kid birth weights (3.8 ± 0.2, 3.6 ± 0.2, and 3.4 ± 0.2 kg; < 0.05), and kid BW at 15 d after birth (6.9 ± 0.2, 6.6 ± 0.2, and 5.6 ± 0.2 kg; < 0.05) for the G35, G15, and GC, respectively. Serum concentrations for total protein, glucose, and cholesterol were not affected ( > 0.05) by treatments. Milk of GC goats showed increased ( < 0.05) percentages for fat, protein, lactose, and nonfat milk solids, whereas total quantities of these variables where higher ( < 0.05) in the G15 and G35 groups. Furthermore, GC dams spent more time seeking their offspring and emitted more low-pitched bleats 4 h postpartum ( < 0.05) in a 2-choice test compared with the G15 and G35 groups. In general, peripartum supplementation promoted a closer dam-kid relationship at 8 h postpartum. Goat performance may be improved in this semiarid region of Mexico with marginal production through supplementation in late gestation.

A total of 12 sexually mature mixed-breed goat bucks were used in this experiment to study the effects of testosterone application (T; 25 mg IM every three days during three weeks) during the period of sexual inactivity (end of March, 26°N) on libido, odour, Sertoli cell number, seminal characteristics and serum testosterone levels. The experimental design was completely random with two groups with six bucks in each group. Reaction time was shorter (P < 0.05) in T bucks (96 ± 45 sec) than in control bucks (258 ± 44 sec). Testosterone treatment increased semen volume (1.2 ± 0.5 vs. 0.3 ± 0.03 ml for T and control bucks, respectively) and total sperm cells/ejaculate (1.32 ± 0.7 vs. 0.33 ± 0.02 x 10 9 for T and control bucks, respectively). Buck's odour (scale 1-5) was more intense (P < 0.05) in T bucks (1.8 ± 0.1) than control bucks (0.6 ± 0.2). Serum testosterone levels were threefold higher in T bucks (8 ng/mL) compared to control bucks (2 ng/mL) after three weeks of exogenous testosterone treatment. It was concluded that testosterone application to sexually inactive goat bucks provoke an increase in serum testosterone which in turn induces an intense sexual behaviour and the improvement of semen quality.