Within the area of sex allocation, one of the topics that has attracted a lot of attention is the sex ratio problem. Fisher (1930) proposed that equal numbers of males and females have been promoted by natural selection and it has an adaptive significance. But the empirical success of Fisher's theory remains doubtful because a sex ratio of 0.50 is also expected from the chromosomal mechanism of...

Crossbred females and male progeny of three terminal sire breeds, namely Charollais, Suffolk and Texel, out of Mule ewes (Bluefaced Leicester sires x Scottish Blackface or Swaledale dams) were compared. Analysis of variance revealed that breed, sex and the year of birth were significant sources of variation (P<0.05) for birth weight. Suffolk sired lambs were significantly heavier than the Charo...

Records of birth weight (BW), weaning weight (WW) and condition score (CS) from 1,467 Brahman and Brahman X Angus crossbred calves from Brahman and crossbred Brahman sires and Brahman, crossbred Brahman and Angus dams were collected at the Subtropical Agricultural Research Station, Brooksville, Florida, from 1971 to 1982. Best linear unbiased estimates (BLUE) of Brahman sire and dam group addit...

Hatchery-reared fish show high mortalities after release to the wild environment. Explanations for this include potentially predetermined genetics, behavioral, and physiological acclimation to fish farm environments, and increased vulnerability to predation and parasitism in the wild. We studied vulnerability to Diplostomum spp. parasites (load of eye flukes in the lenses), immune defense (rela...

Flocks participating in sire referencing schemes can achieve greater genetic gains than those achievable by within-flock selection. However, requirements for joining these schemes can be prohibitive to some producers. The objectives of this study were to determine whether less restrictive schemes or schemes of shorter duration could achieve rates of gain and reduce inbreeding as efficiently as ...

Plasma urea nitrogen can be used as an indicator of N use and excretion by an animal. The objective of this research was to assess the effect of residual feed intake (RFI) on plasma concentration of urea N (PUN) in 188 bulls, heifers, and steers (mean body weight = 652 lb, SD = 82 lb) ranging from 100% Angus to 100% Brahman. Calves were assigned to pens in a GrowSafe feeding facility by sire gr...

Maternal performance of 134 Hereford (H), Brangus (B), and reciprocal crossbred (H x B and B x H) cows from 2 to 7 yr of age was evaluated under semidesert conditions in this study. Calves produced by 2- and 3-yr-old cows were sired by Brangus and Hereford bulls. Calves produced by 4- to 7-yr-old cows were sired by Charolais bulls. Breed of sire and breed of dam of cow affected kilograms of wea...

The objective of this study was to compare body weight, ADG, and feed:gain ratio of antibiotic-free pigs from Yorkshire dams and sired by Yorkshire (YY), Berkshire (BY), Large Black (LBY) or Tamworth (TY) boars. All the crossbred pigs in each of three trials were raised as one group from weaning to finishing in the same deep-bedded hoop, providing a comfortable environment for the animals which...

143) were transported 2,200 km to central Oklahoma. As an estimate of inflammation, concentrations of ceruloplasmin, fibrinogen, and haptoglobin were measured in blood samples collected at weaning, 24 and 72 h post-weaning, and on the day of shipping, 24 and 72 h after arrival. Fixed effects were breed type (n = 9 levels: straightbreds [RR, AA, BB], and crossbreds [RA, AR, RB, BR, AB, BA] where...