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PubMed1999

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.

Animals↗

PubMed1982

Control of growth hormone release in goats: effect of vagal cooling, feeding and artificial distension of the rumen.

It was confirmed that, as in overnight-fasted castrate male sheep, plasma growth hormone (GH) levels also fell in overnight-fasted castrate male goats shortly after they were given hay the following morning and that GH levels could also fall in anticipation of being fed. A further observation was that plasma GH levels usually remained low for 2--3 hours if the goats were allowed to continue eating but that if the hay was removed after only one hour of eating the plasma GH level rose 20--50 min later. Although initial attempts to determine the role of visceral stimuli in the regulation of GH release in castrate male goats by bilateral cooling of exteriorized vagi were inconclusive because of side-effects, they drew attention to the role of rumen distension and activation of stretch receptors in the modulation of GH release. This was investigated by artificial distension of the cranial sac of the rumen with a balloon in a castrate male, overnight-fasted goat prepared with a rumen fistula. Inflation of the balloon with warm water was followed by a fall, and deflation of the balloon by a rise, in plasma GH levels. It is concluded that rumen distension and hence activation of ruminal stretch receptors is a sufficient stimulus to explain the immediate inhibition of GH release by feeding in the goat. As a result of these, and other, observations during this work, it is also suggested that unrestrained release of GH, and hence large oscillations in plasma GH level, may occur in the goat unless it is suppressed by any of several factors, which include activation of rumen stretch receptors by feeding or inflation, anticipation of being fed, stress and metabolic satiety.

Animals↗

PubMed2006

Multiorgan engraftment and differentiation of human cord blood CD34+ Lin- cells in goats assessed by gene expression profiling.

To investigate multitissue engraftment of human primitive hematopoietic cells and their differentiation in goats, human CD34+ Lin- cord blood cells transduced with a GFP vector were transplanted into fetal goats at 45-55 days of gestation. GFP+ cells were detected in hematopoietic and nonhematopoietic organs including blood, bone marrow, spleen, liver, kidney, muscle, lung, and heart of the recipient goats (1.2-36% of all cells examined). We identified human beta2 microglobulin-positive cells in multiple tissues. GFP+ cells sorted from the perfused liver of a transplant goat showed human insulin-like growth factor 1 gene sequences, indicating that the engrafted GFP+ cells were of human origin. A substantial fraction of cells engrafted in goat livers expressed the human hepatocyte-specific antigen, proliferating cell nuclear antigen, albumin, hepatocyte nuclear factor, and GFP. DNA content analysis showed no evidence for cellular fusion. Long-term engraftment of GFP+ cells could be detected in the blood of goats for up to 2 yr. Microarray analysis indicated that human genes from a variety of functional categories were expressed in chimeric livers and blood. The human/goat xenotransplant model provides a unique system to study the kinetics of hematopoietic stem cell engraftment, gene expression, and possible stem cell plasticity under noninjured conditions.

Animals↗

PubMed1998

Glutathione S-transferase of goat lens: evidence for expression of only class mu isoenzymes.

PURPOSE: It has been suggested that glutathione S-transferases (GSTs) of the mammalian ocular lens detoxify various toxicants and cataractogens; therefore, it provides protection against cataractogenesis. In this study the GST isoenzymes of goat lens have been purified and characterized. METHODS: The goat lens homogenate was subjected to affinity chromatography over GSH-linked epoxy activated Sepharose 6B. The isoenzymes of the GST were separated by chromatofocusing on a Mono-P column using FPLC. RESULTS: Two GST isoenzymes, GST 7.2 and GST 6.6, were purified to apparent homogeneity from goat lens. GST 7.2 appeared to be a heterodimer of Mr. 26,500 and Mr. 25,000 subunits, the GST 6.6 showed a homodimeric subunit structure of Mr. 25,000. Western blotting and the N-terminal region amino acid sequence analysis indicated that both isoenzymes of goat lens belong to the mu-class GST. CONCLUSION: Although they share varying degrees of structural correlation, the two isoenzymes of goat lens seem to be the products of two distinct genes. The isoenzyme expression pattern of GST in goat lens is similar to bovine lens, which also contains two isoenzymes belonging only to GST mu.

Animals↗

PubMed1990

Plasma electrolyte concentration in food-deprived goats orally supplemented with potassium chloride.

The aim of the present study was to investigate whether oral potassium supplementation during food deprivation could stimulate rumen electrolyte absorption and maintain plasma electrolyte concentration. Eight goats were subjected to food deprivation in combination with intrarumen loads of potassium chloride or, as a control, mannitol in a change-over design. In addition, four KCl- and four mannitol-treated goats were given an extra KCl load towards the end of the experiment. Food-deprived goats which were given KCl maintained their plasma concentration of Na and Cl, while plasma K concentration increased from 3.6 mM to 4.4 mM. In control goats receiving mannitol during food deprivation, the plasma concentration (mM) decreased from 144 to 140 for Na, 105 to 100 for Cl and from 3.8 to 3.6 for K, but concentrations were restored when these goats were given a load of KCl. The plasma renin activity was suppressed in food-deprived goats receiving KCl, while those given mannitol showed increased activity. It is suggested that the hyponatraemia which occurs in food-deprived ruminants is mainly caused by diminished K intake.

Animals↗

PubMed1991

Tissue protein synthesis in lactating and dry goats.

Intravenous infusion of L-[3H]phenylalanine (Phe) was carried out for 8 h in dry, non-pregnant and lactating dairy goats. Nitrogen balance was positive in the dry group and negative in the lactating group. Whole-body Phe flux was 50% greater in lactating goats (P less than 0.01). Fractional synthesis rates (Ks) of tissue proteins were estimated from plasma- (Ksp) and tissue- (Ksh) specific radioactivities of Phe. In lactating goats, Ksp for mammary gland, duodenum and diaphragm was increased (P less than 0.05). Ksp also tended to increase in liver, kidney and rumen (P less than 0.08) of lactating goats, but was not different in uterus, spleen, caecum or heart. Values of Ksh were higher than Ksp; however, these measures agreed qualitatively. When absolute rates of protein synthesis were calculated, an increased contribution of mammary and visceral organs was seen in lactating goats. Ks and absolute rates of protein synthesis of hind-limb skin were less in lactating goats (P less than 0.05). A decreased proportion of skeletal muscle (P less than 0.05). Decreased rates of muscle and skin protein synthesis would appear to participate in alterations of protein metabolism, permitting lactation to occur at the expense of body reserves.

Animals↗

PubMed1991

The efficiency of chewing during eating and ruminating in goats and sheep.

The total amounts of time spent eating and ruminating per 24 h by goats and sheep were determined. The efficiencies of chewing during eating (mean value of C.EAT) and chewing during ruminating (mean value of C.RUM) on the breakdown of feed particles to below the critical size required to leave the rumen (less than 1.0 mm) were investigated. All studies were done with the animals fed on a chaffed lucerne (Medicago sativa) hay diet. Goats spent more time eating (+3.1 h; P less than 0.01), and less time ruminating (-2.2 h; P less than 0.05) per 24 h, than sheep, when fed hourly at ad lib. intake. The efficiency of chewing during eating (mean value of C.EAT) in breaking down feed particles to less than 1.0 mm was greater in goats (85%; P less than 0.01) than sheep (48%). The process of rumination in sheep served to reduce the feed particles which were greater than 1.0 mm in the rumen to less than 1.0 mm. Sheep tended to be more efficient in this process than goats (59 v. 48%), with the difference not attaining significance (P greater than 0.1). The greater frequency of chews (number of total jaw movements/min) during eating in goats (P less than 0.01), or during ruminating in sheep (P less than 0.001), was the major component explaining differences in efficiency between the two species in both the eating and rumination processes. When corrected for the number of chews/min, the differences in mean value of C.RUM and mean value of C.EAT were not significant between goats and sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗

PubMed1995

Liver triacylglycerol concentrations around parturition in goats with either pre-partum restricted or free access to feed.

The hypothesis was tested that goats allowed ad libitum access to feed during the dry period develop higher post partum hepatic triacylglycerol concentrations than do goats given a restricted amount of feed during the dry period. Goats in their second or more pregnancies were either given a restricted amount of hay, maize silage and concentrate (n = 5) or had free access to this feed mixture while the composition was kept constant (n = 11). After parturition both groups were allowed ad libitum access to feed. Post partum liver triacylglycerol concentrations, as measured in liver biopsies, were significantly raised in goats allowed ad libitum access to feed during the dry period. The increase in liver triacylglycerols was associated with slightly higher plasma concentrations of non-esterified fatty acids but lower serum 3-hydroxybutyrate concentrations. The feeding regimen during the dry period did not significantly influence post partum liver glycogen concentrations and serum levels of glucose, cholesterol, and insulin. The increase in post partum liver triacylglycerol concentrations in the goats allowed ad libitum access to feed instead of a restricted ration during the dry period, was associated with a significant rise in serum alkaline phosphatase activities, whereas other liver function and cell damage indicators in serum, i.e. aspartate aminotransferase, lactate dehydrogenase, gamma glutamyl transpeptidase, and bilirubin, were unchanged. Feed intake after parturition tended to be higher in the goats allowed ad libitum access to feed during the dry period but milk production was significantly raised.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed2002

Effects of the rat hepatic peroxisome proliferator, Wyeth 14,643, on the lactating goat.

Some peroxisome proliferators have been reported to reduce body weight gain in suckling rats, possibly through a lactational effect. Decreases in milk production or nutritional quality, either as a result of peroxisome proliferator-induced reductions in lipid content or alterations in the hormonal milieu necessary for milk production, could result in pup growth retardation. Wyeth-14,643 (WY) is hypolipidemic agent and a potent inducer of hepatic peroxisome proliferation in rats and mice. As is commonly seen with rodent hepatic peroxisome proliferators, WY produces minimal or no peroxisome induction in guinea pigs or non-human primates. Goats are an excellent model for studying lactation, however, their sensitivity to peroxisome proliferating chemicals is not known. The present study was performed to assess the sensitivity of goats to the hypolipidemic and peroxisome proliferator properties of WY and to determine the effects of WY on milk quantity and quality. Six lactating adult female goats were assigned to either control or treated groups. Goats in the treated group were administered WY (40 mg/kg/day) for 14 consecutive days. The goats were milked twice daily in order to maintain lactation and the quantity of milk collected was recorded. Milk quality was evaluated by determining the content of total fat, protein, and carbohydrate in milk samples collected following 7 and 14 days of treatment. WY administration had no effects on final body weight, liver weight or, gross and histopathological findings. Milk quantity and quality were unaffected by treatment. Serum cholesterol and triglyceride levels were reduced by 25% compared to controls, although only the difference in cholesterol was statistically significant. Hepatic beta-oxidation (3 x control) and aromatase (1.5 x control) activities were significantly greater in the treatment group; however, there was no treatment-related effect in the total content of hepatic cytochrome P450. There was no difference in aromatase activity in a pooled ovarian microsome sample. Milk estradiol and prolactin concentrations were not affected by treatment. These findings indicate that goats are weak responders to the hepatic peroxisome proliferator effects of WY. Additionally, the slight serum hypolipidemic effect does not impact milk production or nutritional value.

Animals↗

PubMed1975

Hemoglobin switching in sheep and goats. V. Effect of erythropoietin concentration on in vitro erythroid colony growth and globin synthesis.

Erythroid colonies were generated in response to erythropoietin in plasma clot cultures of sheep and goat bone marrow cells. At low concentration erythropoietin only hemoglobin A (betaA globin) was synthesized in goat cultures, but at high concentrations 50% of the hemoglobin synthesized was hemoglobin C (betaC globin). This effect of erythropoietin on the expression of a specific beta globin gene was manifested only after 72 h in vitro and followed the development of erythroid colonies. Sheep colonies behaved differently from those of goat in that little or no betaC globin synthesis occurred even at high erythropoietin concentration. To investigate this difference, sheep marrow cells were fractionated by unit gravity sedimentation. The erythroid colony-forming cells sedimented more rapidly (3.5-6mm/h) than the hemoglobinized eththroid precursors (1-3.5 mm/h), suggesting that the colonies were formed from an early erythroid precursor, However, the colonies formed from the sheep marrow fractions synthesized only betaA globin even at concentrations of erythropoietin sufficient to stimulate betaC globin synthesis in goat colonies. Morphologically, the goat colonies were larger and more mature than those of the sheep. By 96 h in vitro three-fourths of the goat colonies contained enucleated red cells compared to only 3% of the sheep colonies. Thus, erythropoietin had an equivalent effect in stimulating erythroid colony growth from the marrow of both species although there were both biochemical and morphological differences between the colonies. Hemoglobin switching appeared to require exposure of an early precursor to high erythropoietin concentration, but the results with sheep marrow suggested that the rate of colony growth and cellular maturation might also be important.

Animals↗

PubMed2005

In vivo bone strain and ontogenetic growth patterns in relation to life-history strategies and performance in two vertebrate taxa: goats and emu.

This study examined ontogenetic patterns of limb loading, bone strains, and relative changes in bone geometry to explore the relationship between in vivo mechanics and size-related changes in the limb skeleton of two vertebrate taxa. Despite maintaining similar relative limb loads during ontogeny, bone strain magnitudes in the goat radius and emu tibiotarsus generally increased. However, while the strain increases in the emu tibiotarsus were mostly insignificant, strains within the radii of adult goats were two to four times greater than in young goats. The disparity between ontogenetic strain increases in these taxa resulted from differences in ontogenetic scaling patterns of the cross-sectional bone geometry. While the cross-sectional and second moments of area scaled with negative allometry in the goat radius, these measures were not significantly different from isometry in the emu tibiotarsus. Although the juveniles of both taxa exhibited lower strains and higher safety factors than the adults, the radii of the young goats were more robust relative to the adult goats than were the tibiotarsi of the young compared with adult emu. Differences in ontogenetic growth and strain patterns in the limb bones examined likely result from different threat avoidance strategies and selection pressures in the juveniles of these two taxa.

Animals↗

PubMed1992

Metabolism of [14C]- and [32P]pyridoxal 5'-phosphate and [3H]pyridoxal administered intravenously to pigs and goats.

To gain more information about the kinetics of vitamin B-6 metabolism in vivo, the metabolism of tracer was examined after the simultaneous intravenous administration of [32P] and [14C]pyridoxal phosphate and [3H]pyridoxal in two 93-kg pigs and two 60-kg goats. In the pigs, [14C] removal was monophasic with T1/2 of 16 and 18 min and clearance of 165 and 248 mL/min. In the goats, [14C] removal was biphasic with T1/2 of 49 and 114 min for 0-30 min and 209 and 227 min for 0.5-6 h (clearance 20 and 17 mL/min). Uptake of pyridoxal phosphate by liver and resecretion into the plasma were too small to cause a detectable decrease in the [32P]:[14C] ratio. Pyridoxal removal from plasma was similar in both species, with a half-life of approximately 12 min from 0-30 min and approximately 50 min for 0.5-3 h. Clearance of [3H]pyridoxal in the four animals ranged from 412 to 2258 mL/min. Little [14C] entered the erythrocytes. The [3H] entered readily but was converted to pyridoxal phosphate faster in the pigs than in the goats. [14C] and [3H] were excreted as pyridoxic acid at the same rate. However, during the 54 h after injection the goats excreted approximately 60% of the [14C] doses in the urine compared with approximately 30% in the pigs. About 5-10% of the [14C] and [3H] doses were recovered in goat milk over 54 h. Pyridoxal kinase activity was higher in lactating mammary tissue than in liver, kidney or muscle of goats.

Animals↗

PubMed2003

Phylogeography and origin of Indian domestic goats.

The Indian subcontinent contains 20 well-characterized goat breeds, which vary in their genetic potential for the production of milk, meat, and fibre; disease resistance; heat tolerance; and fecundity. Indian goats make up 20% of the world's goat population, but there has been no extensive study of these economically important animals. Therefore, we have undertaken the present investigation of 363 goats belonging to 10 different breeds from different geographic regions of India using mtDNA sequence data from the HVRI region. We find evidence for population structure and novel lineages in Indian goats and cannot reconcile the genetic diversity found within the major lineage with domestication starting 10,000 years ago from a single mtDNA ancestor. Thus, we propose a more complex origin for domestic goats.

Analysis of Variance↗

PubMed1997

Deterioration of goat sperm viability in milk extenders is due to a bulbourethral 60-kilodalton glycoprotein with triglyceride lipase activity.

The aim of this work was to purify, identify, and characterize the component of goat bulbourethral gland secretion (BUS) responsible for goat sperm deterioration in skim milk extender. BUS extracts promote a decrease in the percentage of motile spermatozoa, deterioration in the quality of movement, breakage of acrosomes, and cellular death of goat spermatozoa diluted in skim milk. A 55- to 60-kDa monomeric glycoprotein (BUSgp60) was purified by cation-exchange, concanavalin A, and heparin-affinity chromatography and was identified as the only BUS component responsible for the deterioration of spermatozoa in milk. The BUSgp60 was shown to display triacylglycerol hydrolase activity, and partial sequences (37 amino acids in all) exhibited 50-70% homology with sequences of various types of pancreatic lipases (PLs), especially PL-related protein 2 (PL-RP2). In addition, porcine PL produced deterioration of goat sperm properties in milk as effectively as BUS and BUSgp60. These results support the preliminary identification of the goat BUSgp60 as a bulbourethral lipase belonging to the PL-RP2 family. Since seminal plasma also contains factors favorable for sperm survival, it is envisaged that, for the best preservation of goat semen, specific inhibitors of this family of lipase could be added into milk-based extenders without eliminating seminal plasma.

Amino Acid Sequence↗

PubMed1999

The xenotransplantation of goat and human hematopoietic cells to sheep fetuses.

Hematopoietic xenografts were carried out in three experiments using goat fetal liver (44-48 days, experiments I and II) or purified human CD 34+ cells (experiment III) as the donor cells. Recipients were sheep fetuses at 41-47 days of gestation. Goat fetal liver cells were either injected without any pretreatment or stimulated by preincubation in a culturing in goat phytohemagglutinin-stimulated lymphocyte supernatant. Human CD 34+ myeloid progenitor cells were purified from bone marrow by minimacs immunomagnetic purification and cultured in medium supplemented with stem cell factor, IL3, and IL6. Goat-sheep chimerism was assessed by flow cytometry analysis (FCA) of peripheral blood and bone marrow cells using a mouse anti-goat CD 45 monoclonal antibody and by karyotype analysis of peripheral blood from goat/sheep chimeras. Human cell engraftment was assessed by polymerase chain reaction amplification of the human DAX1 gene in blood and bone marrow DNA from sheep which had received human cells. In the three experiments, a mean of 76% (26 of 34) of injected fetuses were born alive without any clinical evidence of graft-versus-host disease. Three lambs were found to be goat/sheep chimeric after flow cytometry analysis (peripheral blood and bone marrow) and karyotype (peripheral blood) analysis. Both tissues continued to express goat cells at 6 or 12 months (last assessment) depending on the experiment. No human chimerism was detected using polymerase chain reaction amplification in peripheral blood and bone marrow of any of the six sheep grafted with human cells. These data and those also obtained on other species (human, pig/sheep) show that it is possible to carry out hematopoietic xenografts using the sheep fetus as recipient provided both donor and recipient fetal cells are processed during the period of tolerance to foreign antigens.

Aging↗

PubMed1980

Biological characterization of the virus causing leukoencephalitis and arthritis in goats.

This study describes the biological properties of a strain of virus isolated from tissues of a goat with leukoencephalomyelitis-arthritis. The agent is a retrovirus, having a virion-associated reverse transcriptase enzyme and an antigenic determinant(s) which cross-reacts with the p30 of visna-maedi viruses. Morphogenesis of the virus is also similar to visna virus in terms of virus assembly and the multinucleated giant cell formation which accompanies replication of the latter virus. Despite its cytopathogenic property the goat agent was not lytic in goat cell culture, causing instead a productive infection which persisted through multiple subcultures of the cells. The virus replicated incompletely in sheep cell cultures but could be rescued from the latter, weeks after inoculation, by co-cultivation with goat cells. Our data suggest that this strain of goat leukoencephalitis virus is a variant of the ovine retroviruses with a host range limited to the goat.

Animal Diseases↗

PubMed1987

Antigenic variation of caprine arthritis-encephalitis virus during persistent infection of goats.

Six caprine arthritis-encephalitis virus (CAEV)-free goats kept in strict isolation were inoculated intravenously with a cloned CAEV isolate (virus 020). At 78 weeks post-infection a virus (virus 095) isolated from one of the goats was shown to have the characteristics of CAEV, but was antigenically distinct from virus 020 and two other CAEV isolates by serum neutralization tests. Serum from the goat that had the variant virus neutralized the inoculum virus and the variant virus but serum from other inoculated goats neutralized only the inoculum virus. The variant virus and the inoculum virus were shown to co-exist in the infected goat, but the presence of the antigenic variant did not appear to be associated with an increase in severity of lesions compared with other inoculated goats.

Animals↗

PubMed2006

Functional disruption of the prion protein gene in cloned goats.

The cellular prion protein (PrPC), a membrane glycoprotein anchored to the outer surface of neurons, lymphocytes and other cells, is associated directly with the pathogenesis of the transmissible spongiform encephalopathies (TSEs) occurring mainly in humans, cattle, sheep and goats. Although mice lacking PrPC develop and reproduce normally and are resistant to scrapie infection, large animals lacking PrPC, especially those species in which TSE occurs naturally, are currently not available. Here, five live PRNP+/- goats cloned by gene targeting are reported. Detailed RNA-transcription and protein-expression analysis of one PRNP+/- goat showed that one allele of the caprine PRNP gene had been disrupted functionally. No gross abnormal development or behaviour could be seen in these PRNP+/- goats up to at least 3 months of age. These heterozygous PRNP+/- goats are ready to be used in producing homozygous PRNP-/- goats in which no PrPC should be expressed.

Amyloid↗