Introduction Reproductive performance has greater impact on beef economic returns than does either growth rate or product quality (Trenkle and Wilham, 1977). In most cow-calf operations, females still conceive via the natural breeding bull (Godfrey and Lunstra, 1989). Thus the reproductive capabilities of bulls are of paramount importance. These capabilities are largely influenced by one or mor...

Genetic evaluations of Holstein bulls for February 1997 through May 1998 were examined to determine the value of more frequent evaluation for quicker identification of bulls with changing predicted transmitting abilities (PTA) and of new bulls of superior genetic merit. Changes in PTA between evaluations that were calculated quarterly rather than semiannually were reduced by 30%. About two-thir...

The objective of this experiment was to test in vitro embryo production (IVP) as a tool to estimate fertility performance in zebu bulls using Bayesian inference statistics. Oocytes were matured and fertilized in vitro using sperm cells from three different Zebu bulls (V, T, and G). The three bulls presented similar results with regard to pronuclear formation and blastocyst formation rates. Howe...

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...

banana xanthomonas wilt is a systemic disease of banana plants. we investigated the risk of spreading xanthomonas campestris pv. musacearum (xcm) through asymptomatic mature bunches. samples of banana fingers and rachis from markets within kampala, uganda and at border points of uganda with dr congo, tanzania, rwanda and kenya were tested for the presence of xcm through recovery of the bacteriu...

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...

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...

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 ...