Six Hereford bulls from a line selected with an index of body weight and muscling score were compared with six bulls from a control line to determine if increased growth in the selected line was associated with changes in plasma levels of growth hormone (GH), prolactin (PRL) and (or) thyrotropin (TSH). The predictive value of sire hormone data for growth rate of progeny was also evaluated. Bull...

The effects of sex and slaughter age on growth, feed intake, carcass composition and meat quality attributes of musculus longissimus lumborum were investigated in Charolais × Simmental bulls (n = 12) and heifers (n = 12) reared and finished under identical management conditions. The animals entered the experiment at similar age (251 days) and were slaughtered at 14 or 18 months of age. Bulls ga...

Genetic evaluation strategies were studied using simulated data for three lactation traits in each of two importing and two exporting countries, each running a typical progeny test program. Conversion (CNV), multiple-trait across-country evaluation (MACE) and global animal model (GAM) strategies were considered. Base populations were either unselected, or all males were above average, and expor...

Twelve Charolais bulls were ejaculated once weekly (1• and 10 bulls six times weekly (6• from puberty to 2 years of age to determine the effect of age and ejaculation frequency on semen characteristics, sperm output and testes growth; 6• weekly sperm output at 2 and 3 years of age was determined for each of the 22 bulls. Significant increases as bulls aged were found in sperm concentration, spe...

Background: BVD and IBR are contagious viral diseases highly prevalent in Irish cattle. Despite their significant reproductive and economic impact very little is known about the BVD and IBR status of stock bulls (a bull used for breeding purposes). There are still a high proportion of dairy farms in Ireland that rely on the use of a bull for breeding cattle and ensuring the fertility of the bul...

The aim of this study was to evaluate the usefulness of trans-scrotal ultrasonography and testicular fine needle aspiration cytology in assessing bulls for breeding suitability. These two techniques were also compared with semen analysis. Bulls presented for breeding soundness evaluation were assessed using all three techniques. The findings of each technique were compared. There was agreement ...

The main goal of this study was to test the effectiveness of two molecules of pheromones identified in the urine of cows in estrus at stimulating sexual function and increasing reproductive capacity of bulls. The trial lasted four weeks and the bulls were divided into two groups (experimental and control) with ten bulls. For this experiment we used an intranasal spray comprising the pheromone m...

Thirty-six percent of American Wagyu bulls do not meet the current minimum standards set by the Society of Theriogenology for the breeding soundness exam. In contrast, only 15% of bulls of domestic breeds do not meet the minimum standards. Scrotal circumference measurements of Wagyu are smaller than those of other breeds. The objective of this research was to describe scrotal circumference of W...

The objective of this study was to evaluate effects of feeding monensin (MON) or a multivalent polyclonal antibody preparation (PAP) against several rumen microorganisms on feedlot performance, carcass characteristics, blood gas profile, and rumenitis of Bos indicus biotype (BT) yearling bulls. The study was designed as a completely randomized design with a 3 × 2 factorial arrangement, replicat...

Postweaning growth and pubertal traits were studied in Hereford, Angus, Red Poll, Brown Swiss, Hereford-Angus crossbred (HXA) and Angus-Hereford crossbred (AX H) bulls from 7 through 13 months of age. Pubertal factors characterized included body weight, testicular size, hormone concentrations, sexual aggressiveness and sperm production. Puberty was defined as the age at which a bull first produ...