a deterministic model was employed to simulate various progeny testing programs compatible with the conditions of holstein dairy cattle population in iran. in simulated programs, the selection intensity of bulls was increased by increasing the ratio of cow population in mate with young bulls. selection accuracy in the programs was fixed because of the fixed progeny group. economic efficiency (t...

Stud bull plays an important role in the development of animal husbandry. Detailed knowledge about maintenance behavior of stud bulls is essential for practicing better management conditions in the farm to support the artificial insemination (AI) industry demand. Therefore, a comparative study was conducted on stud bulls to evaluate the effect of genetic group, season, genetic group × season in...

The reproductive performance of Angus (A), Polled Hereford (PH) and Santa Gertrudis (SG) bulls was compared when exposed to 40 cows/bull vs 80 cows/two bulls during a 90- to 95-d breeding period on pasture. Cows were A, PH and SG straightbreds and crossbreds of these breeds. Each year, cows were allotted at random within breed composition and age of dam to breeding groups. A replicate consisted...

Objective of the present study was to document the semen producing ability, productive life and genetic ability for lactation milk yield of Sahiwal bulls used for artificial insemination (AI) in Punjab and to find the impact of AI bulls on the improvement of Sahiwal cattle. Data from Semen Production Unit (SPU), Qadirabad, Sahiwal, Pakistan were used for this purpose. A repeatability animal mod...

An experiment was conducted to determine the effects of long-term feeding of cottonseed meal on the reproductive traits of Holstein bulls. Holstein bulls approximately 6 mo of age were placed on the following treatments: 1) soybean meal + corn (CON); 2) cottonseed meal + corn (GOS); and 3) cottonseed meal + 4,000 IU vitamin E x bull(-1) x d(-1) (G+4E). The GOS and G+4E diets were formulated to ...

AIM To compare the seminal attributes of neat, pre-freeze (at equilibration), and post-freeze (24 h after freezing) semen in pure and crossbred Jersey bulls. MATERIALS AND METHODS Total 36 ejaculates (3 ejaculates from each bull) were collected from 6 pure Jersey and 6 crossbred Jersey bulls and evaluated for various seminal attributes during neat, pre-freeze, and post-freeze semen. RESULTS...

In some production settings, beef bulls are mixed at the beginning of the finishing period to obtain homogeneous groups to facilitate finishing and to produce more homogeneous carcasses. Given the stress induced by mixing, we questioned whether this practice was profitable. Sixty-four young bulls were finished in groups of four over 8 mo. They were either mixed or unmixed and had either homogen...

Artificial insemination (AI) subfertility is an indication of failure of AI with frozen-thawed sperm classified as normal by conventional semen examination. Recently, 8 AI-subfertile Japanese Black cattle (S1-S8) were identified using the routine AI test or in vivo fertilization test, which included AI with frozen-thawed sperm of superovulated females and subsequent non-surgical recovery of pre...

Behavioural and endrocrin%gical data on African elephants (Loxodonta africana) are integrated to provide a hypothesis oj the adaptations reflected in the phenomenon of musth in bulls. Occupation oj home ranges, movements. male dominance hierarchies and intra-specific agonistic behaviour are reviewed. Bulls in musth leave their home range, travel far and jast, initiate more contacts with distant...

This study evaluated the plasma membrane integrity, acrosomal membrane integrity, and mitochondrial membrane potential of Nelore bull sperm from early puberty to early sexual maturity and their associations with sperm motility and vigor, the mass motility of the spermatozoa (wave motion), scrotal circumference, and testosterone. Sixty Nelore bulls aged 18 to 19 months were divided into four lot...