In this study, the effectiveness of intra-testicular ethanol and calcium chloride administrations was compared for chemical-castration in 12 mixbred young bulls (12-15 months old and 250-400 kg). Ten ml of absolute ethanol or 10 ml of a 30 % calcium chloride solution were administered intra-testicularly in each testicle which were removed with the open surgical technique after 60 days for histo...

The effects of unilateral castration (UC) and induced unilateral cryptorchidism (UCR) on basal plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone, and on the responses of these hormones to gonadotropin releasing hormone (GnRH), were investigated in bulls altered at 3, 6 or 9 months of age. Blood plasma was collected before and after GnRH (200 micrograms) stimul...

A total of 240 Holstein bulls (121 ± 2.0 kg initial BW; 99 ± 1.0 d of age), from 2 consecutive fattening cycles, were randomly allocated in 1 of 6 pens and assigned to 1 of the 3 treatments consisting of different concentrate feeder designs: a control feeder with 4 feeding spaces (CF), a feeder with less concentrate capacity (CFL), and a single-space feeder with lateral protections (SF). Each p...

The objective of this study was to evaluate postpartum resumption of ovulatory cycles among primiparous, suckled beef cows that were exposed continuously to mature bulls beginning at various intervals after calving. We sought to determine whether cumulative distributions of proportions of cows resuming ovarian cycles and interval from the start of bull exposure to resumption of ovarian cycling ...

To determine the effect of energy intake on semen characteristics and libido, pubertal Angus (n = 10) and Senepol (n = 10) bulls (approximately 16 months of age and 816 lb) were stratified by age and weight between two treatments. Treatments were diets that provided 75% (LOW) or 150% (HIGH) of maintenance metabolizable energy requirements. Diets were group fed for 112 days (June through Septemb...

Reproductive efficiency, obtained through cost-effective measures, is the most important factor affecting profitability of the cow-calf enterprise. The reproductive efficiency of bulls and females both contribute to expressed reproductive performance of the cow herd. It is quite possible that although females are culled for low expressed reproduction, sires with only average reproductive potent...

This study was conducted at the National Artificial Insemination Center, Ethiopia with an objective of evaluating breeding soundness, effect of age and breed on semen quality and fertility of bulls. The evaluation involved 45bulls (36 breeding and 11 pre-service young bulls) consisting of Holstein Friesian, Jersey, Borana and Cross breeds (Borana X Holstein Frisian). Semen was collected using a...

The present was conducted to separate heparin binding proteins (HBP) of capacitated sperm extracts and determine their relationship with acrosome reaction and semen fertility of bulls (n=30). Fourteen immunoreactive bands in capacitated spermatozoa of bulls (135, 100, 75, 70, 65, 55, 48, 45, 33, 31, 26, 24, 20 and 18 kDa) were detected in western blots following incubation with anti-HBP antibod...

Wild bull Asian elephants spend time in all-male groups. Therefore, managers of ex situ populations increasingly house bulls together. We examined the social interactions five at Denver Zoo, using instantaneous sampling to compare across adolescent and mature bulls, with a history prior integration this group compared no history. Both age significantly affected behavior. Adolescent exhibited mo...

This experiment was designed to determine 1) if exposure of firstcalf suckled beef cows to mature bulls in the first 30 days, after 30 days, or continuously post partum reduces the postpartum anestrous period and 2) if exposure to bulls alters the first service pregnancy rate. Postpartum first-calf suckled crossbred (Angus x Hereford; Hereford x Angus) cows were randomly assigned to be 1) expos...