Time of ovulation in goats (Capra hircus) induced to superovulate with PMSG

The timing of ovulation in feral goats treated with 1200 i.u. PMSG +/- 50 micrograms GnRH was studied by repeated laparoscopy. Experiment 1 established that superovulation began as early as 30 h after withdrawal of progestagen-impregnated sponges and was not completed at 54 h if goats received PMSG alone. GnRH synchronized ovulation, leading to 91% of ovulations appearing between 36 and 48 h after sponges were withdrawn. Experiment 2 established that superovulation continued until up to 77 h in goats treated only with PMSG. The stress of repeated laparoscopy appeared to delay or abolish ovulation in some females. The mean (+/- s.e.) ovulation rate was greater in goats treated with GnRH (12.7 +/- 1.3) than in those that received PMSG only (9.7 +/- 1.1; P less than 0.05). Out of 47 of the females in Exp. 1, 43 had one or more corpora lutea at laparoscopy 24 h after withdrawal of progestagen. These early corpora lutea were associated with an increased concentration of plasma progesterone during the periovulatory period. Experiment 3 provided evidence that these corpora lutea arose before the withdrawal of progestagen-impregnated sponges.     

Induction of estrus with intramuscular injections of GnRH or PMSG in lactating goats (Capra hircus ) primed with a progestagen during seasonal anestrus

In Experiment 1, goats in seasonal anestrus (n=154) were treated with sponges impregnated with 1 of 2 types of progestagen (MAP or FGA) followed by PMSG (400 IU im) 48 h before sponge removal. The type of progestagen used had no effect on kidding, abortion, pseudogestation, multiple births, stillbirths, number of live births per doe or gestation length. In Experiment 2, lactating goats (n=24) in seasonal anestrus were treated with progestagen sponges (MAP). At sponge removal they received one of the following treatments: 1 injection of PMSG (400 IU im), 1 injection of GnRH (125 mug im; GnRH-1), or 2 injections of GnRH (125 mug/injection im; GnRH-2) at a 48 h interval. Serum samples were taken at 6-h intervals for 96 h, starting 12 h after sponge removal. Heterologous radioimmunoassays were validated for the measurements of goat FSH, LH, E(2) and P(4). The onset of estrus (P=0.004), mean doe receptivity (P=0.0006), maximum preovulatory E(2) concentrations (P=0.0001) and LH peak concentrations (P=0.08) occurred significantly later for GnRH-1 and GnRH-2 than for PMSG treatment. The PMSG treatment induced a preovulatory LH peak in a greater number of goats (P=0.05) and gave a higher gestation rate than GnRH-1 and GnRH-2 treatments (57 vs 0 vs 12%; P=0.03). It is likely that the GnRH treatments administered did not reactivate the hypothalamo-pituitary-gonadal axis. Thus, intramuscular injections of GnRH in lactating goats primed with a progestagen were not as effective in regulating reproductive performance during seasonal anestrus as were injections of PMSG.     

Cloned goats (Capra hircus) from adult ear cells

The average number of available oocytes recovered per ovary collected during the breeding season in dairy goats was 5.5 (1815/330). 66.17% (1201/1815) of oocytes extruded the first polar body after maturation in vitro for 20 h. 75.44% (906/1201) of matured oocytes with membrane evagination around the MII chromosomes were enucleated. Ear skin fibroblast cells were derived from an adult female dining Grey goat (C. hircus). The cells were cryopreserved in liquid nitrogen after passage 2. Thawed cells were further cultured for 3-6 passages and were subjected to serum starvation by 0.5% FBS for 2-10 d, then used as donor cells for nuclear transfer. 98.12% (889/906) of the enucleated oocytes were reconstructed by intracytoplasmic injection of karyoplast. The reconstructed embryos were activated by 5μ mol/L ionomycin for 4.5 min and further activated by culturing with 6-dimethylaminopurine (6-DMAP) for 3 h. After 36 h of culture in mCR1aaBF, 76.69% (645/841) of the cloned embryos cleaved. There were no signifi     

Evidence of ovulation in goats (Capra hircus ) with short estrous cycle and its occurrence in the tropics

The influence of season and exposure to buck on the length of the estrous cycle were determined in 32 normally cycling native goats of different ages and parity. The estrous cycle durations were classified as short, medium and long. Ten goats (31%) exhibited medium length estrous cycles; 22 animals (69%) exhibited a combination of short, medium and long estrous cycles. Of the 155 estrous cycles studied, 15% were short, 72% were medium and 13% were long. Short estrous cycles were significantly shorter (P < 0.01) in estrus duration than medium or long estrous cycles. Significant differences (P < 0.05) for estrous cycle length and estrus duration were found between does but not within does. The presence of a buck for 8 to 16 h showed no significant effect on the length of the estrous cycle or on estrus duration, but a 24-h exposure period to a buck yielded shorter estrous cycles and estrus duration than found in the unexposed control group. Estrous cycles were significantly shorter (P < 0.01) in October, when rainfall is 57.9% of the annual total, and significantly longer (P < 0.01) in February, when rainfall is low at 0.2% of the annual total. A negative linear relationship (r = -0.87) was observed between estrous cycle and rainfall. Twenty-eight (90.3 %) of the short estrous cycles were ovulatory. The short cycles had a relatively lower ovulation rate than medium and long estrous cycles. The results indicate that the short estrous cycle in goats is associated with ovulation, and its occurrence in the tropics is related to rainfall.     

Red blood cell potassium types of angora goats (Capra hircus)

Two distinct K phenotypes with normal frequency distribution curves were found and identified as low (LK) and high (HK) potassium types in the red blood cells of 748 Angora goats. The division between the two types was arbitrarily assigned at 24.9 meq/l. Of the two KRBC level types; the LK type was predominating, its curve showed evidence of leptokurtosis and was negatively skewed. The HK type had a curve slightly mesokurtic and the population was normal with respect to skewness.     

Work performance, thermoregulation and muscle metabolism in thyroidectomized goats (Capra hircus)

1. Thyroid hormone deficiency resulted in a markedly diminished work efficiency of goats exercising on a treadmill at an ambient temperature of 30 degrees C. 2. The close relationship between the exercise-induced increase in core temperature and the magnitude of evaporative heat loss, characteristic for intact animals, was nearly completely abolished after thyroidectomy. 3. Muscle glycogen utilization and lactic acid accumulation during exercise were enhanced in thyroidectomized animals in spite of the lower work rate and shorter duration of exercise in comparison with euthyroid goats.     

Rumen protozoal diversity in the Spanish ibex (Capra pyrenaica hispanica) as compared with domestic goats (Capra hircus)

Rumen protozoal diversity in the Spanish ibex (SI) was studied in males (n=4), females (n=7) and young (n=4) from the Maestrazgo (Spain) and contrasted with domestic goats (n=3; DG) of the same region. There were no differences among SI types in protozoal concentration or in the number of protozoal species. Only protozoa from the genus Entodinium were observed in SI (seven species), the highest numbers corresponding to E. damae, E. ovibos and E. parvum. DG harboured threefold more species than SI. Nine to 10 Entodinium spp. were observed, but E. ovibos was absent from the rumen of DG, and E. damae was in only one animal. E. caudatum (caudatum, dubardi and lobospinosum morphotypes) occurred in the highest percentage, and E. dubardi, E. exiguum and E. parvum were quite abundant. Four genera of the subfamily Diplodiniinae and the genera Isotricha and Dasytricha from the family Isotrichidae were detected in DG. Epidinium (two DG) and Ophryoscolex (one DG) were also observed. Denaturing gradient gel electrophoresis analysis agreed with microscopic classification, showing up to 8 and 16 bands in SI and DG samples, respectively. The three DG clustered together (similarity index over 0.84), and separately from SI (similarity index over 0.86), with only 0.58 similarity between host species.     

Mating tactics of male feral goats (Capra hircus): risks and benefits

Intense competition between males for reproduction has led to the evolution of alternative mating tactics (AMTs). Feral goat males usually use a tactic called tending, in which they defend oestrous females from other males. Males may also use a second mating tactic called coursing, in which they gain access to oestrous females by disturbing a tending pair. Herein, we examine estimated mating success (EMS) and risks of using these tactics. Tending was only used by mature (≥4 years old), higher-ranking males and accounted for 75% of EMS. Coursing was used by males of all ages and dominance ranks, and accounted for 25% of EMS. Using coursing, male kids achieved 8% of EMS. Mature males achieved 92% of EMS. Both age and dominance rank were related to EMS, but age was not important after its relationship with dominance was controlled. Tending bouts were, on average, ca. 30 min long, while coursing bouts only averaged ca. 2 min. Males were more likely to suffer a butt while coursing than while tending, and formerly tending males were responsible for most butts. Kids that coursed had the highest risk of being butted. In most AMTs, there are reductions in the risks in relation to low fitness benefits. However, we found that the risks of butts during coursing were high, while our evidence suggests that the EMS was probably low. Nevertheless, the existence of an effective AMT in male feral goats may have an important influence on the intensity of sexual selection and the effective population size.     

Social information, social feeding, and competition in group-living goats (Capra hircus)

There are both benefits (e.g., social information) and costs(e.g., intraspecific competition) for individuals foraging ingroups. To ascertain how group-foraging goats (Capra hircus)deal with these trade-offs, we asked 1) do goats use socialinformation to make foraging decisions and 2) how do they adjusttheir intake rate in light of having attracted by other groupmembers? To establish whether goats use social information,we recorded their initial choice of different quality food patcheswhen they were ignorant of patch quality and when they couldobserve others foraging. After determining that goats use socialinformation, we recorded intake rates while they fed alone andin the presence of potential competitors. Intake rate increasedas the number of competitors increased. Interestingly, lonegoats achieved an intake rate that was higher than when onecompetitor was present but similar to when two or more competitorswere present. Faster intake rates may allow herbivores to ingesta larger portion of the available food before competing groupmembers arrive at the patch. This however, does not explainthe high intake rates achieved when the goats were alone. Weprovide 2 potential explanations: 1) faster intake rates area response to greater risk incurred by lone individuals, theloss of social information, and the fear of being left behindby the group and 2) when foraging alone, intake rate is no longera trade-off between reducing competition and acquiring socialinformation. Thus, individuals are able to feed close to theirmaximum rate.     

Concurrent recall of serially learned visual discrimination problems in dwarf goats (Capra hircus)

Studies of cognitive ability in farm animals are valuable, not only because they provide indicators of the commonality of comparative influence, but understanding farm animal cognition may also aid in management and treatment procedures. Here, eight dwarf goats (Capra hircus) learned a series of 10 visual four-choice discriminations using an automated device that allowed individual ad lib. access to the test setup while staying in a familiar environment and normal social setting. The animals were trained on each problem for 5 days, followed by concurrent testing of the current against the previous problem. Once all 10 problems had been learned, they were tested concurrently over the course of 9 days. In initial training, all goats achieved criterion learning levels on nearly all problems within 2 days and under 200 trials. Concurrently presenting the problems trained in adjacent sessions did not impair performance on either problem relative to single-problem learning. Upon concurrent presentation of all 10 previously learned problems, at least half were well-remembered immediately. Although this test revealed a recency effect (later problems were better remembered), many early-learned problems were also well-retained, and 10-item relearning was quite quick. These results show that dwarf goats can retain multiple-problem information proficiently and can do so over periods of several weeks. From an ecological point of view, the ability to form numerous associations between visual cues offered by specific plants and food quality is an important pre-grazing mechanism that helps goats exploit variation in vegetation and graze selectively.     

Pulsatile GnRH administration stimulates the number of pituitary GnRH receptors in seasonally anoestrous ewes

Twenty seasonally anoestrous ewes were pretreated with progesterone for 4 days and divided into four equal groups. Ewes in Group 1 received no GnRH treatment and were slaughtered immediately after progesterone removal. Ewes in Groups 2, 3 and 4 received i.v. injections of 250 ng GnRH every 2 h for 36 h starting at the time of progesterone removal. Ewes in Group 2 were slaughtered immediately after the 36 h GnRH pulsing, while ewes in Groups 3 and 4 were given a bolus injection of 125 micrograms GnRH at this time and were slaughtered 2 and 10 h after the bolus injection, respectively. Blood samples were collected every 30 min from ewes in Group 4 only, from 4 h before the start of GnRH treatment until 10 h after the bolus injection. Pulsing with GnRH resulted in episodic release of LH, and the bolus injection of GnRH was immediately followed by a preovulatory type LH surge in those ewes in which an endogenous surge had no already begun. The pituitary GnRH receptor numbers were significantly higher for the ewes in Group 2 than for any of the other treatment groups, while there was no significant difference in the receptor numbers between Groups 1, 3 and 4. The results suggest an up-regulation of GnRH receptors resulting from pulsatile GnRH therapy.     

Cryoprotective role of organic Zn and Cu supplementation in goats (Capra hircus) diet

The current study focused on cryopreservation and assessment of characters of post-thaw semen of indigenous Osmanabadi bucks maintained with standard diet, supplemented with different concentrations of organic zinc (Zn), copper (Cu) or in combination, for a period of 180 days. The different doses of organic Zn and Cu were fed per kg DM basis, Zn groups (low: Zn20, medium: Zn40 and high: Zn60), Cu groups: (low: Cu12.5, medium: Cu25 and high: Cu37.5) and combination of Zn + Cu groups (low: Zn20 + Cu12.5, medium: Zn40 + Cu25 and high: Zn60 + Cu37.5) respectively. The control group bucks were maintained mainly on the basal diet without any additional mineral supplementation. Two hundred and forty (240) semen samples were collected from 40 bucks aged 11 months, through electro ejaculator method, processed and analysed for sperm quality parameters both at pre freeze and post-thaw stage. The semen samples were diluted in Tris egg yolk extender, cooled and equilibrated for 4 h at 5 °C, cryopreserved using programmable freezer (PLANER Kryo 360–1.7) and stored at −196 °C. The organic trace minerals (Zn, Cu and Zn + Cu) protected the spermatozoa against the cryoinjury and maintained higher post-thaw semen parameters except in high Zn group. Additional feeding of organic Cu and Zn to bucks had a protective role and resulted in higher sperm liveability, plasma membrane and acrosome integrities, motility and velocity and reduced oxidative stress in supplemented goats (P < 0.05).     

Inhibition of luteal function by oxytocin antagonist in goats (Capra hircus).

Early corpus luteum development in nonpregnant and pregnant goats was characterized by a steady increase in peripheral plasma concentrations of progesterone and a high release of prostacyclin (PGI-2) but low release of prostaglandin F-2 alpha (PGF-2 alpha). Jugular administration of oxytocin antagonist (OXA) (0.2 microgram/kg/day) on the day of oestrus and for 3 days thereafter to cyclic and mated goats, significantly (P less than 0.001) inhibited progesterone and prostaglandin secretion and reduced conception rate. Co-administration of PGI-2 (200 micrograms/day) with OXA resulted in a steady increase of progesterone and establishment of pregnancy, but co-administration of PGF-2 alpha (175 micrograms/day) with OXA had no effect. It is suggested that oxytocin is required for early development of the corpus luteum and such effects may be mediated via PGI-2 production.     

Vasopressin increases blood glucose in pygmy goats (Capra hircus) by an alpha-adrenergic mechanism.

1. Twelve adult pygmy goats were used to investigate the mechanism of vasopressin (VP) induced hyperglycaemia. 2. VP (0.4 microgram/kg or 0.75 microgram/kg body weight) injected i.p. produced a long lasting hyperglycaemia. 3. This hyperglycaemia was partly reversed by alpha-adrenergic antagonists with an affinity to alpha 1- and alpha 2-adrenergic receptors (phentolamine) or to alpha 2-adrenergic receptors (yohimbine). An alpha 1-adrenergic agonist (xylometazoline) produced a short-term hyperglycaemia. 4. The ganglion blocking agent hexamethonium also reversed VP's hyperglycaemic effect. 5. It is concluded that VP's hyperglycaemic effect in pygmy goats is due to an increase in sympathetic outflow and not to a direct action on the liver.     

Effect of dexamethasone on the estrous cycle length in Black Bengal goats (Capra hircus )

In an experiment to examine the relationships between adrenals and reproductive cycle, 10 mg dexamethasone (a synthetic glucocorticoid) were injected intramuscularly twice daily for 10 d to four Black Bengal goats, beginning on Day 11 of the synchronized estrous cycle. The extended length of the sexual cycle was monitored by the clinical signs of anestrus. Laparotomy was performed to examine the status of the ovary of an 8, 9, 10 and 8 d extended cycle, respectively. The length of the next cycle was normal. Endogenous cortisol values were suppressed for 11, 13, 20 and 24 d, respectively. It is thought that dexamethasone caused prolonged luteal function either by the suppression of prostaglandin F(2)alpha synthesis or by the suppression of pituitary stimulation of follicular growth.     

Effect of PGI-2 on uterine activity in vivo in non-pregnant ovariectomized goats (Capra hircus)

Jugular administration of 200 micrograms PGI-2 salt significantly reduced spontaneous uterine activity in ovariectomized, oestrogen-primed goats; the effect was acute and persisted for about 3 h. Peripheral plasma concentrations of 6-keto-PGF-1 alpha, the stable metabolite of PGI-2, decreased to 50% of initial values after 30 min; but at the start of uterine recovery were in excess of 2 ng.ml-1. Uterine reactivity to both oxytocin and PGF-2 alpha after PGI-2 administration was unaffected.     

Power of 22 microsatellite markers in fluorescent multiplexes for parentage testing in goats (Capra hircus)

Two multiplex systems, each containing 11 microsatellite loci, were developed for semiautomated parentage testing in goats. Eight of the loci originate from goats, nine from cattle and five from sheep. Eighteen of the loci have been mapped to 16 different autosomes (in goats and cattle). Parentage exclusion probabilities were computed from allele frequencies in approximately 30 unrelated individuals from each of four economically important breeds: Mongolian Native Cashmere, Turkish Angora, Swiss Saanen, and Spanish Murciana-Grenadina. In cases where genotypes are known for one parent and an offspring, the 22 markers will exclude an (erroneously) alleged parent with a probability of > 0.999999 in the cashmere breed, > 0.99999 in Angora and Murciana-Grenadina, and > 0.9999 in Saanen. The multiplexes provide very high power for individual identification as the probability of finding two identical genotypes for the 22 loci is < 1 in 1.10(15) in each of the four breeds. The multiplexes will also be useful for studies of population structure, history, and diversity in goats and also in wild Capra species that represent important resources for genetic improvement of domestic breeds.