The objective of this study was to compare fixed-time AI pregnancy rate in Angus crossbred beef cows inseminated with frozen-thawed or fresh-extended semen. Two ejaculates from each of two Angus bulls were collected by artificial vagina and pooled for each bull. The pooled semen from each bull was divided into two aliquots; Aliquot 1 was extended using Caprogen (LIC, Hamilton, New Zealand) to a...

The effects of dam previous reproductive status (PRS) on the pre-adjustment of weaning weight for genetic evaluation (WWT) was examined for Santa Gertrudis (SANTA), Brahman (BRAH) and Tropical Composite (TCOMP) breeds of beef cattle. Weaning weight records were classified into 3 groups according to the dam’s PRS: whether in the last year, she had reared a bull calf (PBC), a heifer calf (PHC) or...

The effect of artificial insemination (AI), embryo transfer (ET) to bull dams (BD), and sexed semen (SS) to cow dams (CD) with and without controlling inbreeding were studied using stochastic simulation. Three levels of embryo transfer (no ET, ET on all BD, and ET on 20% of BD), five levels of sexed semen (no SS: control, SS-X on all CD, SS-X on 20% CD, SS-Y on all CD, and SS-Y on 20% CD), thre...

The importance of the bull in a cattle breeding program often is underestimated. A cow is responsible for half the genetic material in only one calf each year, while the bull is responsible for half the genetic material in 20 to 50 calves. The bull’s ability to locate cows in estrus and breed them is clearly vital to a successful breeding program. Bulls differ in physical appearance, fertility ...

Lethal recessive genes that cause early embryo loss are difficult to detect. Nonreturn rate at 70 d after first insemination (NR) was evaluated as a trait of the embryo using 1,739,055 first-service records from 1,251 Holstein bulls represented as both service sires and sires of cows. Effects modeled included herd-year-season, parity of cow, sire of cow, service bull, interaction of service bul...

The principal objective of this study was to derive an improved procedure for cryopreservation of swamp buffalo (Bubalus bubalis) spermatozoa. Experiments were conducted to determine effects of cooling rate, intermediate plunge temperature and warming rate on motility and acrosome integrity of spermatozoa. Spermatozoa were obtained from three bulls (three ejaculates/bull) and were subjected to ...

Merit of service sires for Holstein cows designated as genetically elite for yield in January 1990 was calculated to determine the contribution of these cows to genetic progress. Service sires were determined from sires of registered female progeny because male progeny were selectively registered. Primary data were 1295 elite cows (top 1%) that had a daughter produced from a mating in the 6 mo ...

Sixty-four zebu cows, comprised mainly of Bunaji cattle aged between 3 and 7 years old, were involved in an intensive artificial insemination programme. The study was conducted during the breeding period (May-October), and cows were inseminated with freshly prepared Friesian semen when they stood to be mounted by the vasectomised bull or herdmates. Fertility was measured by serum progesterone (...

In each of two experiments, 120 pregnant beef cows were stratified by body condition score, BW, breed, and age, randomly divided into six groups of 20, and assigned to one of six 5.1-ha bermudagrass (Cynodon dactylon [L.] Pers.) pastures (two replicates/ treatment) in early January to evaluate the use of winter-annual pasture as a supplement. All cows in Exp. 1 and 2 had ad libitum access to be...

This pilot study demonstrates the use of multiphasic analysis of non-return data to study effects of inbreeding on conception rate, calving rate and calving rate given conception when only non-return data is available. The results indicate that inbreeding of the cow mainly affects late embryonic mortality while inbreeding of the embryo mainly affects foetal mortality. However, interpretation of...