In many mammal species, androgen levels in males are elevated during periods of mating activity, often to facilitate aggressive behavior between males over access to fertile females. However, this pattern might be less obvious in species with a rather low male-male aggression rate, or in those that are not strictly seasonal breeders. A complex social structure, as well as additional social and ...

Seven batches of 25% water-phase, oil-in-water vaccine were prepared from whole cultures of Tritrichomonas foetus. Two inoculations were given, spaced 6 weeks apart, to virgin heifers and infected bulls. A significant reduction (P less than 0.01) in the duration of infection in vaccinated heifers was seen when they were challenged by being bred to a bull infected with the same isolate as that c...

The objectives of this study were to examine the growth, DMI, and feeding behaviors of Angus and Hereford bulls; identify the relationships between feeding behaviors and variation in DMI and residual feed intake (RFI); and determine the value of feeding behaviors in predicting DMI. Individual DMI was measured in Angus bulls (n=189; initial BW=427±3.4 kg) and Hereford bulls (n=146; initial BW=41...

Serum transminases and phosphatases were assayed in fertile and infertile cattle and buffalo bulls. Serum glutamate pyruvate transaminase (SGPT) did not differ significantly in relation to fertility and species. Serum glutamate oxaloacetate transaminase (SGOT) was higher in infertile than fertile bulls in both the species. The values were higher in cattle than buffalo bulls. The differences wer...

The temporal pattern of the endocrine changes associated with puberty were studied using 52 bulls born in October or April. Blood samples were taken weekly and at 30-min intervals for 5 h every 4 wk. Bulls were castrated at one of six 4-wk intervals between 12 and 32 wk and blood samples were taken. Season of birth affected concentrations of testosterone (greater for spring-born) in intact bull...

The levels of biochemical parameters in the blood serum of Simmental service bulls were studied. The research was conducted on twelve bulls at the age of four to seven. The blood was taken on four occasions by needle biopsy from the vena jugularis externa. In the samples of blood serum, the activities were specified of alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glut...

Objective: This study was conducted to assess the prevalence of different types of gross testicular disorders in bulls, and to evaluate the associations with sampling year, age, and body condition. Materials and methods: In this study, a total of 398 apparently healthy bulls were randomly selected that were brought from different parts of eastern Ethiopia to the Haramaya University abattoir for...

AIM The aim of the present investigation was to optimize the age at first use (AAFU) of semen of Murrah breeding bulls, which will help in early selection of bulls under progeny testing program for improving the reproductive performance in the herd. MATERIALS AND METHODS The data on AAFU, conception rate based on first A.I. (CRFAI), overall conception rate (OCR), and birth weight (B.WT) of 57...

The importance of milk proteins and the positive effect of administration of growth hormone (GH) on milk production, and the presence in some dairy cattle lines of greater GH concentrations prompted us to examine the presence of restriction fragment length polymorphism at the GH gene using the restriction enzyme TaqI and to investigate associations between this polymorphism in Simmental cows an...

The present study was conducted to detect polymorphism at growth hormone gene in Karan Fries bulls. A 428 bp fragment of growth hormone gene spanning over 4 exon, 4 intron and 5 exon was amplified and digested with AluI restriction enzyme to identify polymorphism at this locus. Karan Fries bulls were found to be polymorphic at this locus. Two genotypes LL and LV were identified in Karan Fries w...