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.     

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.     

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.     

Mineral deficiency status of ranging zebu (Bos indicus) cattle around the Gilgel Gibe catchment, Ethiopia

Mineral deficiencies in cattle, widespread in East Africa, impair optimal health and production and consequently place a great burden on the farmers' income. Therefore, detection of shortages and imbalances of specific minerals is essential. Our objective was to evaluate the mineral status of grazing cattle around the Gilgel Gibe catchment in Ethiopia and associated factors. In study I, individual animal plasma and herd faecal Ca, P, Mg, Na, K, S, Fe, Zn, Mn and Cu concentrations were determined in adult zebu cattle (Bos indicus; n?=?90) grazing at three altitudes around the catchment, whilst recording body condition score and sex. In study II, liver samples of adult male zebu cattle (n?=?53) were analysed for Cu, Zn, Fe, Se and Mo concentrations and inspected for parasitic infections. Plasma and liver analyses revealed a Cu deficiency problem in the area, since 68 and 47 % of cattle, respectively, were Cu deprived according to diagnostic criteria for Bos taurus cattle. High hepatic Mo concentrations in 17 % of cases might reflect excessive dietary Mo intake. Liver Se and plasma Na concentrations were too low in 92 and 80 % of cattle. Plasma Mn concentrations were largely below the detection limit. Plasma Cu as well as Ca concentrations were lower in the lowest altitude compared to the highest altitude group (P?<?0.05), whereas lean to medium cattle had lower plasma Cu concentrations (P?<?0.05). No differences in hepatic mineral concentrations were detected between cattle with different types of parasitic infection. In conclusion, bovine mineral deficiencies were present in the Gilgel Gibe area and were associated with grazing altitude and body condition score.     

Seasonal influences on gonadal and extragonadal sperm reserves in Small East African zebu (Bos indicus) bulls in Ethiopia

Summary Body weight and scrotal circumference (SC) data were takenante mortem and genitalia collected after slaughter from Small East African zebu (SEAZ) bulls slaughtered during the wet (n=46) and the dry (n=53) seasons. Bulls slaughtered during the wet season were significantly heavier (47 kg) and had significantly larger SC measurements (3·3 cm) than those slaughtered during the dry season. Mean (±s.e.m.) paired testes weights were 233·7±13·8 and 292·8±11·3 g and epididymal weights 26·8±0·9 and 35·9±1·1 g in bulls slaughtered during the dry and wet seasons, respectively. Daily sperm production rates and epididymal sperm reserves were 2·2±0·1×10⁹ and 3·0±0·1×10⁹; and 16·1±0·3×10⁹ and 17·6±0·4×10⁹ in bulls slaughtered during the dry and wet seasons, respectively. These differences were significant. It was concluded that season affected reproductive capacity of zebu bulls probably due to variations in the quality and quantity of nutrition. However, the confounding effects of ambient temperature and nutrition on reproductive capacity of zebu bulls in tropical regions need further examinations.

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Résumé Le poids vif et la circonférence scrotale de petits zébus males à courtes cornes d'Afrique de l'est a été mesuré anti-mortem au cours de la saison humide (n=46) et de la saison séche (n=53). Parallèlement, des organes génitaux ont été prélevés après abattage. Les veaux abattus pendant la saison humide étaient incontestablement plus lourds (47 kg) et les mesures de leur circonférence scrotale étaient bien plus importantes (3,3 cm) que celles des animaux abattus au cours de la saison sèche. Les poids moyens (+s.e.m.) des deux testicules étaient de 233,7±13,8 et 292,8±11,3 g; les poids de l'epididyme étaient de 26,8±0,9 et 35,9±1,1 g chez les males abattus durant la saison sèche et la saison humide. Les taux quotidiens de production de sperme ainsi que les réserves de l'epididyme étaient de 2,2±0,1×10⁹ et 3,0±0,1×10⁹ et 16,1±0,3×10⁹ et 17,6±0,4×10⁹ chez les males abattus durant la saison sèche et la saison humide. Les différences étaient significatives. On a conclu que les saisons affectaient la capacité de reproduction des zébus males probablement à cause des variations qualitatives et quantitatives de l'alimentation. Cependant, les effects interactifs de la température ambiante et de l'alimentation sur la capacité de reproduction des zébus males sous des climats tropicaux nécessitent de plus amples examens. Resumen Se tomaron el datos sobre peso corporal y la circunferencia escrotal (CE) ante-morten y después de sacrificados, en toros Cebú peque?os de Africa del Este. Para el efecto, se sacrificaron 46 animales durante la estación lluviosa y 53 durante la estacioń seca. Los toros sacrificados durante la estación seca fueron más pesados (47 kg) y tuvieron CE mayores (3·3 cm), que aquellos sacrificados durante la estación seca. El promedio de peso de los testículos fue de 233·7±13·8 y 298·8±11·3 g y de los epidídimos 26·8±0·9 y 35·9±1·1 g en toros sacrificados durante la estación seca y lluviosa, respectivamente. La tasa diaria de producción de esperma y las reservas epididimales fueron 2·2±0·1×10⁹ y 3·0±0·1×10⁹ y 16·1±0·3×10⁹ y 17·6±0·4×10⁹ en toros sacrificados durante la estación seca y lluviosa, respectivamente. Las diferencias fueron significativas. Se concluye que la estación afecta la capacidad reproductiva de los toros Cebú, probablemente debido a la cantidad y calidad de la nutrición. Sin embargo, la interacción entre ambiente y nutrición sobre la capacidad reproductiva del Cebú en regiones tropicales, necesita más estudios.

     

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 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%.     

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.     

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.     

Physiological responses of newborn Bos indicus and Bos indicus x Bos taurus calves after exposure to cold

Brahman (n = 9) and 1/2 Simmental x 1/4 Brahman x 1/4 Hereford (n = 11) calves were utilized to determine the influence of exposure to cold on the physiology of the neonate. All calves were removed from their dams within 20 min of birth and prior to suckling. Calves were assigned randomly within breed to either a warm (W; 31 degrees C) or cold (C; 4 degrees C) environmental treatment group. Jugular blood samples were collected via indwelling catheters at 20-min intervals for 180 min. At 100 to 120 min of sampling, all calves were given 1.2 liters of colostrum from their dams via stomach tube. At 120 min, C calves were placed in the W environment. Calf vigor score (CVS) and rectal temperature were determined at each time blood was collected. Serum or plasma was analyzed for glucose (GLU), lactate (LAC), blood urea nitrogen (BUN), hemoglobin (HEM), triglyceride (TRG), triiodothyronine (T3), thyroxine (T4), insulin (INS), cortisol (CORT) and nonesterified fatty acid (NEFA) concentration. Rectal temperature was lower (P less than .01) in C Brahman than in W Brahman and C or W crossbred calves. Crossbred calves had higher (P less than .01) CVS than Brahman calves. Calves in W had lower (P less than .01) GLU than C calves. Brahman calves had higher GLU, LAC, BUN, TRG, T3, T4 and CORT (P less than .05) than crossbred calves. The C Brahman calves had the highest (P less than .05) TRG, CORT, T3 and T4 of all groups. Concentration of NEFA were higher (P less than .01) in C than in W calves.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

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.