The length of the cycle of seminiferous epithelium in goats (Capra hircus).

This is the first report in literature showing the length of the seminiferous epithelium cycle in goats. In the present study, the duration of spermatogenesis was estimated using intratesticular injections of tritiated thymidine. Animals were castrated at 4 h, 7 days, and 11 days after injections. The duration of each spermatogenic cycle in goats is 10.6 +/- 0.5 days (SEM). Considering that the total duration of spermatogenesis takes about 4.5 cycles of seminiferous epithelium, spermatogenesis was estimated to last 47.7 days. The approximate primary spermatocytes life span is 14.1 days, while spermiogenesis in goats lasts 14.9 days. Staging in goats was based on the tubular morphology, where 8 stages of the cycle are yielded for all species. The relative stage frequencies in goats, based on 400 seminiferous tubule cross sections for each animal were as follows: stage 1: 15.8 +/- 1.0%; stage 2: 12.8 +/- 0.5%; stage 3: 20.5 +/- 0.9%; stage 4: 10.7 +/- 0.7%; stage 5: 11.6 +/- 0.6%; stage 6: 9.3 +/- 1.1%; stage 7: 7.6 +/- 0.4%; stage 8: 11.7 +/- 0.6%. The pre-meiotic, meiotic and post-meiotic phases' relative frequencies were 49.1%, 10.7% and 40.2%, respectively. The duration of spermatogenesis in goats is very similar to that found in rams.     

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     

Effects of oxytocin and an oxytocin antagonist on testosterone secretion during the oestrous cycle of the goat (Capra hircus)

Oxytocin at a dose of 100 i.u. injected subcutaneously (s.c.) daily to goats between Days 3 and 6 of the oestrous cycle caused a significant increase in testosterone secretion compared with saline-treated animals. An oxytocin antagonist (0.2 micrograms/kg) injected intra-arterially between Days 12 and 18 of the oestrous cycle or simultaneously with oxytocin between Days 3 and 6 blocked the increased release of testosterone and occurrence of oestrus. It is suggested that oxytocin-induced oestrus may occur via testosterone secretion.     

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.     

Exogenous GnRH induces ovulation in seasonally anoestrous lactating goats (Capra hircus)

A specific sheep LH radioimmunoassay was validated for the measurement of goat LH, and used to monitor luteal-phase LH episodes and the preavulatory LH surge in progestagen sponge-synchronized cycling goats. No luteal-phase LH episodes were detected during 12 h of frequent (15-min) blood sampling in 2 goats. A preovulatory LH surge was recorded in 5/5 goats, with a mean amplitude of 45.4 +/- 7.2 ng/ml and a mean time of onset of 38.4 +/- 1.2 h after removal of a progestagen-impregnated sponge. In anoestrous goats, single i.v. injections of 1000 and 2000 ng GnRH induced LH episodes with a mean amplitude of 2.04 +/- 0.11 and 3.67 +/- 0.06 ng/ml respectively, but injections of 250 or 500 ng did not consistently elevate LH concentrations. Progestagen-primed, seasonally anoestrous lactating goats were treated with repeated injections of 1500 ng GnRH (every 2 h for 52 or 78 h) in May 1985 or 1986. All 10 had kidded in March of the same year, and were consequently at peak lactation at the time of GnRH treatment. A preovulatory LH surge was detected in 9 goats with a mean time of onset of 59.5 +/- 2.9 h (1985) or 39.6 +/- 3.3 h (1986) after vaginal sponge removal. All animals displayed oestrus and ovulated, and 9 of the goats were mated: in 5 of these animals pregnancies were successfully carried to term. The results show episodic LH release in response to GnRH and indicate that ovulation can be induced in seasonally anoestrous goats, even at peak lactation, and normal pregnancies may result.     

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.     

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.     

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.     

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.     

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.     

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.     

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).     

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.     

Evidence for prostaglandin involvement in early luteal regression of the superovulated nanny goat (Capra hircus)

Feral does of various ages were treated with intravaginal progestagen sponges for 16 days to synchronize oestrus. On Day 2 before sponge removal the goats were given 1200 i.u. PMSG to induce superovulation: 6 of the goats were also injected every 12 h with flunixin meglumine, a prostaglandin (PG) synthetase inhibitor, from Day 3 to 7 of the synchronized oestrous cycle. Jugular blood samples were collected from all females into heparinized syringes at daily intervals over the 2 days before sponge removal, twice daily for the next 2 days, then at hourly intervals from 09:00 to 17:00 h for 2 days and then twice daily for a further 2 days, for measurement of plasma progesterone and the PGF metabolite 13,14-dihydro-15-keto-PGF (PGFM) by radioimmunoassay. Intermittent surges in plasma PGFM concentrations were observed in hourly samples collected from 4/4 untreated females but in only 2/6 of the inhibitor-treated females (P less than 0.05), and the peak plasma PGFM concentrations were reduced in these 2 inhibitor-treated goats compared with the control goats. The corpora lutea (CL) of the inhibitor-treated females appeared to be functional as indicated by the plasma progesterone profile and endoscopic examination of CL. In the control females, however, there was evidence of premature regression of CL. These results suggest that the premature release of PGF-2 alpha may be the cause of premature regression of CL in nanny goats induced to superovulate.     

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.