The capability of bulls to distribute their genetics is dependant upon their fertility, whether they are used for natural breeding or A.I. In turn, herd reproductive performance has been shown to have a greater impact on economic returns than either growth rate or product quality (Wiltbank 1994). Here, chute-side math indicates it takes approximately 5 generations (15 years) using bulls of 10% ...

Twenty-one Simmental crossbred bulls (311 -+ 11 kg, 9 mo of age) were used to determine the effect of feeding 10, 12 or 14% CP on concentrations of hormones in blood and the relationship of these hormones to composition of gain. Six bulls were slaughtered on d 0 to provide an estimate of initial carcass composition (9-11 rib section). Remaining bulls were assigned to dietary treatments. Blood s...

The objectives of this study were to examine the effects of castration on the calpain proteinase system (mu-calpain, m-calpain, and calpastatin) activities and meat tenderness. Six each, MARC III bulls and steers were slaughtered at approximately 12 mo of age. Longissimus muscle samples were obtained for determining myofibril fragmentation index, Warner-Bratzler shear force, and sensory panel e...

The Y-chromosomal TSPY gene is one of the highest copy number mammalian protein coding gene and represents a unique biological model to study various aspects of genomic copy number variations. This study investigated the age-related copy number variability of the bovine TSPY gene, a new and unstudied aspect of the biology of TSPY that has been shown to vary among cattle breeds, individual bulls...

Serum samples from 51 apparently healthy breeding bulls were screened for bovine herpesvirus-1 (BHV-1) antibodies using an avidin-biotin enzyme-linked immunosorbent assay, revealing a sero-positive prevalence rate of 45.09%. Semen samples were then collected from 12 of the sero-positive and 12 of the sero-negative bulls and tested for BHV-1 antigen using both a virus isolation assay and a polym...

The availability of genomic evaluations since 2008 has resulted in many changes to dairy cattle breeding programs. One such change has been the increased contribution of young bulls (0.8 to 3.9 yr old) to those programs. The increased use of young bulls was investigated using pedigree data and breeding records obtained from the US national dairy database (Beltsville, MD). The adoption of genoty...

Mechanisms of testicular thermoregulation, the relationship of scrotal, testicular vascular cone (TVC), and testicular morphology with thermoregulatory capability, and their effects on semen quality and sperm production were studied in 20 Bos indicus, 28 crossbred, and 26 Bos taurus bulls. The ratio of testicular artery length and volume to testicular volume were larger (P<0.05) in B. indicus a...

Sixty semen ejaculates from 10 mature bulls, 5 each of Jafarabadi and Mehsana breed, were studied for sperm motility and velocity parameters of fresh and frozen-thawed spermatozoa using computer assisted sperm analyzer (CASA). The mean values of motile and progressively motile spermatozoa observed in fresh semen of Jafarabadi and Mehsana bulls (79.77±1.62 and 61.80±1.85, and 78.90±1.22 and 61.3...

Canadian and US evaluations of Holstein bulls were compared for longevity measures (433 bulls) and somatic cell score (354 bulls). Bulls were required to have a birth year of > or = 1975, daughter information from > or = 20 herds, and a reliability of > or = 50% in both Canada and the US. The number of bulls with longevity evaluations was greater for early years because longevity information wa...

Adipose tissue in the loin muscle area of beef cattle as a marbling factor is directly associated with beef quality. To elucidate whether properties of proteins involved in depot specific adipose tissue were sex-dependent, we analyzed protein expression of intramuscular adipose tissue (IMAT) and omental adipose tissue (OMAT) from Hanwoo cows, steers, and bulls of Korean native beef cattle by li...