Studies on the Ovarian Development in Zebu Cattle (Bos indicus)

In a study of 71 female foetuses, gonadal blastema was observed at 1.5 cm crown rump length (CRL). Oogonial cells entered the meiotic prophase at 3.5-6.0 cm CRL, which was arrested at the dictyotene stage to produce primary oocytes which formed primordial follicles. Primordial follicles were observed at 6-8 cm CRL. All germinal cells were at dictyotene by 20-24 cm CRL and follicles developed to primary and secondary stages. Folliculogenesis dominated further ovarian development and reached a peak between 32 and 35 cm CRL. In seven of the 12 foetuses measuring between 41 and 72 cm CRL, many follicles were atretic and some luteinized. The luteal bodies were composed of hypertrophied theca and granulosa cells with homogeneous and eosinophilic cytoplasm.     

Foetal and calf wastage in Bos indicus cross beef genotypes

The prevalence, stages and causes of foetal and calf wastage were determined in Brahman (1/2 B, 3/4 B) and Sahiwal (1/2 Sah, 3/4 Sah) and high grade Sahiwal (HGSah) genotypes over a 12-year period. The mean total loss from pregnancy being first diagnosed to weaning was 13.5% (range 9.4 to 19.0%) and was not influenced by cow age. Across all age groups total losses were significantly lower in 1/2 B (11.8%) and 3/4 B (11.7%) than in 1/2 Sah (16.3%) and 3/4 Sah (19.4%) which were in turn significantly lower than in HG Sah (26.5%). Mean prenatal, perinatal and postnatal losses were 3.5%, 4.4% and 5.6%, respectively. For prenatal losses, 42.4% occurred in early-, 34.8% in mid- and 23.0% in late gestation, the prevalence being influenced only by year effects. Perinatal losses were lowest in 3/4 B (2.9%) and highest in 3/4 Sah (8.3%) with other genotypes intermediate. Postnatal losses were lowest in 1/2 B (4.1%) and 3/4 B (5.0%), intermediate for 1/2 Sah (7.2%) and 3/4 Sah (6.2%) and highest in HG Sah (15.5%). In Brahmans, important causes of perinatal and postnatal losses were from unknown causes, and in Sahiwals from bottle teats, unknown causes and factors influenced by the cow. Bottle teats were mostly in cows older than 2 years with the majority being in Sahiwals. A high proportion (44%) of the postnatal losses occurred by 14 days after birth.     

The relationship of plasma leptin concentration and puberty in Holstein bull calves (Bos taurus)

The objective of this experiment was to study the changes of plasma leptin concentration during puberty and its relationship with testosterone level and testis dimensions in Holstein bull calves. Six Iranian Holstein bull calves with approximately 6 months of age were used. Semen evaluation was conducted at 1‐month interval to determine the puberty state. To detect the plasma leptin and testosterone changes, blood samples were collected from the jugular vein during pre‐puberty (6–7 months of age), puberty (8–9 months of age) and post‐puberty (10–11 months of age). In addition, body weight (BW), body condition score (BCS) and testicular width and length were measured at 3‐week intervals. The effects of time (age) on total sperm number and percentage of progressive motility of sperm, plasma concentration of leptin and testosterone, amplitude and frequencies of testosterone, BW, BCS, testicular dimensions were significant. Sperm number and progressive motility during post‐puberty were higher than those during puberty and pre‐puberty. Plasma concentration of leptin during the pre‐puberty was higher than those during puberty and post‐puberty (p < 0.01). Mean plasma testosterone concentrations during puberty were higher than those during pre‐puberty (p < 0.05). BW, BCS and testicular dimensions consistently increased throughout the trial. Results indicated that in growing bull calves, plasma concentrations of leptin decreased during puberty, while circulating testosterone increased.     

Cow/calf preweaning efficiency of Nellore and Bos taurus x Bos indicus crosses

The objectives of this study were to determine if percentage Bos taurus (0 or 50%) of the cow had an effect on ME requirements and milk production, and to compare cow/calf efficiency among 3 mating systems. Metabolizable energy requirements were estimated during a feeding trial that encompassed a gestation and lactation feeding trial for each of 2 groups of cows. Cows were 0 or 50% Bos taurus (100 or 50% Nellore) breed type: Nellore cows (NL; n = 10) mated to Nellore bulls, NL cows (n = 9) mated to Angus bulls, Angus x Nellore (ANL; n = 10) and Simmental x Nellore (SNL; n = 10) cows mated to Canchim (5/8 Charolais 3/8 Zebu) bulls. Cows were individually fed a total mixed diet that contained 11.3% CP and 2.23 Mcal of ME/kg of DM. At 14-d intervals, cows and calves were weighed and the amount of DM was adjusted to keep shrunk BW and BCS of cows constant. Beginning at 38 d of age, corn silage was available to calves ad libitum. Milk production at 42, 98, 126, and 180 d postpartum was measured using the weigh-suckle-weigh technique. At 190 d of age, calves were slaughtered and body composition estimated using 9-10-11th-rib section to obtain energy deposition. Regression of BW change on daily ME intake (MEI) was used to estimate MEI at zero BW change. Increase in percentage Bos taurus had a significant effect on daily ME requirements (Mcal/d) during pregnancy (P < 0.01) and lactation (P < 0.01). Percentage Bos taurus had a positive linear effect on maintenance requirements of pregnant (P = 0.07) and lactating (P < 0.01) cows; during pregnancy, the ME requirements were 91 and 86% of those in lactation (131 +/- 3.5 vs. 145 +/- 3.4 Mcal x kg(-0.75) x d(-1)) for the 0 and 50% B. taurus groups, respectively. The 50% B. taurus cows, ANL and SNL, suckling crossbred calves had greater total MEI (4,319 +/- 61 Mcal; P < 0.01) than 0% B. taurus cows suckling NL (3,484 +/- 86 Mcal) or ANL calves (3,600 +/- 91 Mcal). The 0% B. taurus cows suckling ANL calves were more efficient (45.3 +/- 1.6 g/Mcal; P = 0.03) than straightbred NL (35.1 +/- 1.5 g/Mcal) and ANL or SNL pairs (41.0 +/- 1.0 g/Mcal). Under the conditions of this study, crossbreeding improved cow/ calf efficiency and showed an advantage for cows that have lower energy requirements.     

A Quantitative Study of Muscle Development in the Bovine Foetus (Bos indicus)

The investigation was carried out in order to quantify the changes in various cell parameters which take place in the normal prenatal development bovine muscle. Sections of muscles, taken from 36 Zebu foetuses (Bos indicns) of about 75 to 245 days gestation, were examined microscopically. Results are given on the numbers and sizes of myotubes and myofibres seen section at various stages of development. The relative contribution of increases in cell size and cell number to overall muscle size increase are discussed.     

Spermatogenesis in Bali cattle (Bos sondaicus) and hybrids with Bos indicus and Bos taurus

Semen quality, testis size and efficiency of sperm production in Bali cattle (Bos sondaicus) and hybrids with Bos indicus and Bos taurus were determined. Mean (+/- SEM) daily sperm production per gram of testis parenchyma (DSPG) in six purebred Bali bulls was 12.2 +/- 0.7 x 10(6). F1 B sondaicus cross B taurus bulls and F1 B sondaicus cross B indicus bulls were sterile. Spermatogenesis was arrested at the late primary spermatocyte stage. In 11 B sondaicus cross B indicus crosses, mean DSPG was lower than in the purebred B sondaicus, although four (one 1/4 B sondaicus, one 3/4 B sondaicus, one 5/8 B sondaicus inter se and one 3/8 B sondaicus inter se) exhibited DSPG levels similar to the foundation stock. Semen from those crossbreeds which exhibited complete spermatogenesis was more variable in terms of spermatozoal concentration, percentage of spermatozoa exhibiting progressive motility and levels of spermatozoal abnormalities. In crossbreeds where sperm production was reduced or absent, there was seminiferous epithelial dysfunction, manifested as an increased frequency of degenerative late pachytene and diplotene primary spermatocytes and germinal cells occurring later in the cycle, or in extreme cases, as complete arrest of spermatogenesis at the late primary spermatocyte stage.     

Pharmacokinetics of ivermectin in zebu Gobra (Bos indicus)

Plasma disposition kinetics of ivermectin was evaluated in a West African cattle breed. Five clinically healthy zebu Gobra cattle (Bos indicus) weighing 220-270 kg were treated (0.2 mg kg-1) with a commercially available ivermectin formulation for cattle. Blood samples were collected by jugular puncture at different times between 0.5 h and 40 days post-treatment. After plasma extraction and derivatization, samples were analysed by HPLC with fluorescence detection. Ivermectin was detected in plasma between 30 min and 20 days post-treatment. The observed peak plasma concentration (Cmax) was 46.3+/-13.8 ng ml-1 and the time to reach Cmax (t(max)) was 0.9+/-0.2 day. The values for the absorption half-life (t1/2ab) and the elimination half-life (t1/2el) were 0.3+/-0.2 and 2.8+/-0.7 days, respectively. The calculated area under the concentration-time curve (AUC) was 185.2+/-12.1 ng day ml-1 and the mean residence time (MRT) was 4.2+/-1.3 days. The availability of ivermectin is low in zebu Gobra in comparison to other breeds cattle but equivalent to that reported in the yak and is likely to be due to physiological characteristics of this breed.     

Pharmacokinetics of diminazene in female Boran (Bos indicus) cattle

The disposition kinetics and bioavailability of diminazene in five healthy heifers were determined after single intravenous (i.v.) and intramuscular (i.m.) administration of the drug in sequence with a wash-out period between administrations of 6 weeks. Intact diminazene in plasma, whole blood and urine samples was analysed using high-performance liquid chromatography. Nonlinear regression analysis of the i.v. and i.m. data indicated that, for either route, the plasma disappearance curves of diminazene were best described by triexponential equations. The i.v. bolus was followed by rapid and biphasic distribution with half-life values of 0.04 h and 0.58 h, V_d(_ss) was 1.91 ± 0.42 1/kg, elimination half-life was 31.71 h while CI averaged 1.74 ± 0.40 ml/min/kg. Within 30 min of the i.v. dose, the erythrocyte/plasma partition ratio of diminazene was 0.30 ± 0.15. Diminazene was rapidly absorbed following i.m. administration; t _½k_a was 0.60 h. C_max, 4.68 ± 1.12 μg/ml, was attained in 10–15 min and systemic availability was 102.42 ± 7.25%. The half-life of the terminal disappearance phase was 145.48 h. About 8.26% of the i.m. dose was excreted intact in the urine within the first 24 h of treatment. In vitro , diminazene was bound to bovine plasma albumin to the extent of 38.01–91.10%.     

Differences in copper and selenium metabolism between Angus (Bos taurus) and Brahman (Bos indicus) cattle

A 2-yr study was conducted at the Range Cattle Research and Education Center, University of Florida – Institute of Food and Agricultural Sciences (IFAS) (Ona, FL), to evaluate differences in the metabolism of Cu and Se of Angus (Bos taurus) and Brahman (Bos indicus) cattle. Thirty-two pregnant beef cows (n = 8 Brahman and 8 Angus/yr) were enrolled in the study in the first trimester of gestation. This study consisted of three phases: 1) restriction (day 0 to 90), 2) supplementation (day 91 to 150), and 3) calving. During all three phases, cows were individually fed and housed in partially covered drylot pens. During the restriction and supplementation phases, cows were provided a 1.5 kg/d of a grain-based concentrate supplement, which was fortified with flowers of S (50 g of supplemental S/cow daily; restriction phase) or Cu and Se (100 and 3 mg/d of Cu and Se, respectively; supplementation phase). Blood and liver samples were collected from all cows at 30 d intervals and from both cows and calves within 24 h of calving. Colostrum and milk samples were collected at calving and 7 d after birth. All data were analyzed using the MIXED procedure of SAS, where cow and calf were the experimental unit. During the restriction phase, a breed × day effect (P = 0.03) was observed where Brahman had greater liver Cu concentration than Angus cows in all sampling days. For liver Se concentration, a tendency (P = 0.07) for a breed effect was observed where Angus cows tended to have greater liver Se concentration than Brahman. During the supplementation phase, breed (P < 0.001) and day (P < 0.01) effects were observed, where Brahman cows had greater liver Cu concentration than Angus. For liver Se concentration, a day effect (P < 0.001) was observed, where liver Se concentration increased (P < 0.001) from day 90 to 120 and remained unchanged (P = 0.86) until day 150. At calving, no effects of breed (P = 0.34) were observed for liver Cu concentration of cows; however, Brahman calves tended (P = 0.09) to have greater liver Cu concentration than Angus calves. For Se liver concentration at calving, Angus cows tended (P = 0.07) to have greater liver Se concentration than Brahman cows; however, no breed differences (P = 0.70) were observed for liver Se concentration of calves at birth. In summary, substantial differences in multiple indicators of Cu and Se status were observed between Angus and Brahman cattle, implying that Angus and Brahman cattle possibly have different mechanisms to maintain adequate Cu and Se status.     

Blood Supply in the Tongue of Nellore Bos indicus (Linnaeus, 1758)

Aspects of the vascularization of the tongue of Nellore Bos indicus ( Linnaeus, 1758) were evaluated through the vascular injection technique (with latex-type Neoprene 450, Du Pont do Brasil S.A. and Sulvinil coloring, Glassurit), fixed in formaldehyde at 7% and dissected with magnifying glass. The material was collected at Goiás Carnes Freezer Warehouse in Goiania, Goias. It was found that the deep lingual artery penetrated the lower lateral region of the prominence of the dorsal area of the tongue, advancing rostrally between the hyoid bone and the hypoglossal muscle. In the intravisceral initial third, the artery represents the deep, sinuous continuation branch of the lingual artery, in which path the sublingual artery was stressed in the ventral plan. Then, the artery deepened in the interior of the hypoglossal muscles and genioglossal, supplying dorsal branches (from three to nine) for the lingual torus; from one to five dorsal collateral branches for the lingual cavity; and one or two ventral collateral branches. At the lingual apex, the artery undergoes bifurcation supplying collateral, dorsal and ventral branches with anastomoses between the parallel vessels in the same antimere and between branches of lower caliber hierarchy between opposite antemeres. The large presence of microvessels indicates a significant blood supply to the organ. These results, in comparison with those found in literature, suggest a peculiar vascular pattern for this cattle breed of Indian origin.     

Fertility in zebu cattle (Bos indicus) after prostaglandin administration and artificial insemination.

A total of 137 cycling zebu cows, each receiving a single dose of prostaglandin PGF(2alpha)were used in an oestrus synchronization programme on three different farms. Of the cows on the three farms, 60.6 and 90.5% showed overt oestrus and luteolysis, respectively. Pregnancy rate to fixed time inseminations following single injection of PGF(2alpha)was 61.4% for farm 1, significantly higher than the values of 45.7 and 46.9% for farms 2 and 3, respectively. The pregnancy rates to second service of rebred cows were 53.3, 50.0 and 50.0% for the three farms, respectively, with no significant differences between each.Fertility classification of the cows based on progesterone (P(4)) concentration showed that 6.6% of cows on the three farms were incorrectly diagnosed as having corpora lutea; 2.9% of them had incomplete luteolysis and 5.1% may have lost their embryos between days 21 and 45 post-insemination. The pregnancy rate was 10% higher in the rainy season than in the dry season. Cows with body condition scores of 3 and 4 had a higher overall pregnancy rates than those with a body condition score of 2. The findings of this study further confirm the luteolytic efficacy of prostaglandin in inducing oestrus in zebu cattle and indicate that the nutritional status of the cows must be satisfactory before embarking on oestrus synchronization programmes.     

Milk protein loci polymorphism in taurine (Bos taurus) and zebu (Bos indicus) populations bred in hot climate

The genetic variation at four milk protein loci α_s1‐casein (CSN1S1), β‐casein (CSN2), κ‐casein (CSN3) and β‐lactoglobulin (LGB) was investigated in 358 animals belonging to seven populations well adapted to hot climatic conditions, reared in Africa and Italy. Bos taurus (Somba, Lagune and Modicana), Bos indicus (Sudanese Zebu Peul, Azaouak and Adamawa), and B. taurus × B. indicus (Borgou) were studied by adapting different molecular methodologies to evaluate their genetic variability. All loci were polymorphic and a new CSN2 synonymous variant, named A²′, was detected and characterized. Noteworthy differences in the distribution of alleles and haplotypes were observed between zebuine and taurine cattle showing that milk protein polymorphism is suited for discriminating B. taurus from B. indicus efficiently, and also taurine breeds. Milk protein loci, being positively selected loci, can also provide information about the occurrence of germplasm particularly useful for breeding strategies and production improvement.     

Evaluation of reproductive traits in Bos taurus and Bos indicus crossbred heifers: relationship of age at puberty to length of the postpartum interval to estrus.

Records of age at puberty (AAP) and duration of the postpartum interval to estrus (PPI) for heifers calving first at 2 yr of age were used to determine the relationship between the two reproductive traits. The study from which these records were obtained was designed in a 2 x 2 x 2 factorial arrangement of treatments. Angus x Hereford (AH; n = 148) and Brahman x Hereford (BH; n = 148) heifers were allotted within breed after weaning by weight into light (LW) and heavy (HW) weight blocks. Heifers were assigned by age to different levels of energy (low or high) in diets calculated to reach a target weight of 55% (LE) or 65% (HE) of their projected mature weight by the onset of the breeding period. Data were analyzed within breed and included only records for which both AAP and PPI were available. Pearson correlation coefficients for AAP to PPI were r = -.12 (P = .20) and r = .05 (P = .71) for AH and BH, respectively. Eliminating animals that experienced dystocia from the analyses yielded correlations of r = -.27 (P = .02) and r = .06 (P = .65) for Ah (n = 69) and BH (n = 51), respectively. When energy level, weight block, and energy level x weight block were included in the model for PPI, analyses of variance indicated that PPI among AH heifers was influenced most by the weight at which heifers began the trial after weaning (P = .01) but not by energy level (P = .23) or the interaction of energy level x weight block (P = .48).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of 48-hour calf withdrawal on conception rates of Bos indicus cows and calf weaning weights in extensive production systems

Sixty multiparous Brahman-type cows were randomly selected in the early postpartum period and equally allocated into a calf removal group (RG) and a non-removal group (NRG). Calves from cows in the RG were removed for 48 h prior to the breeding season and returned afterwards, whereas in the NRG, calves remained with their dams until weaning. Weaning weights were corrected to 205?days. Conception rates (CRs) were 76?% for RG and 55?% for NRG but did not differ (p?>?0.05). CR was correlated with calving to breeding interval and body condition score at the onset of the breeding season. Product-limit survival curves vs breeding to conception interval differed significantly (p?相似文献   

Initial Development of Bovine Placentation (Bos indicus) from the Point of View of the Allantois and Amnion

The aim of this study was to perform a morphological characterization of the initial bovine placental development, between 20 and 70 days post-insemination (p.i.), with emphasis on the differentiation of the allantois and amnion. After collection, the conceptuses were dissected, macroscopically measured and photographically documented. The extraembryonic membranes were cut into fragments measuring 5 cm², and then fixed in 4% paraformaldehyde for analysis using light microscopy, and in 2.5% glutaraldehyde for use in scanning and transmission electron microscopy. The extraembryonic and fetal membranes presented variable degrees of development throughout the periods analysed. The macroscopic appearance of vascularization of the allantois, its attempt to merge with the chorium and the effective appearance of the first cotyledons in development were the events observed from 30 to 40 days of pregnancy. The measurements of the amnion increased gradually as gestation developed. The allantoic epithelia presented cellular dimorphism from 20 to 25 days of pregnancy, but was shown to be immature from 60 to 70 days of pregnancy.     

Milk protein polymorphisms in cattle (Bos indicus), mithun (Bos frontalis) and yak (Bos grunniens) breeds and their hybrids indigenous to Bhutan

In the current study, milk protein variation was examined in cattle (Bos indicus), mithun (Bos frontalis), yak (Bos grunniens) and their hybrid populations in Bhutan to estimate genetic variability, conduct genetic characterization and assess the possibility of gene flow between mithun and cattle. Isoelectric focusing of 372 milk samples from 11 populations detected four molecular types of β‐lactoglobulin (A, B, E and M), five molecular types of α_S1‐casein (A, B, C, E and X) and three molecular types of k‐casein (A, B and X). Mithun and yak shared alleles but were found to exhibit different allele frequencies for the proteins studied. The degree of genetic variability within populations was measured by average heterozygosity and ranged from 24–40% in cattle, 26% for yak and 33% for mithun. We also resolved the traditional mithun and cattle hybridization system via principal component analysis. Our results suggested secondary introgression of mithun genes to the village Thrabum population, and a close genetic relationship between Bhutanese indigenous cattle and Indian cattle.