The effect of growth rate from birth through 30 months of age on the reproductive performance of Polled Hereford heifers calving as 2-year-olds was examined. Heifers with high gains during the first winter as weanlings had higher breeding efficiency when bred as yearlings, had larger pelvic areas as 2-year-olds, gave birth to larger calves, had less calving difficulty at first parturition and h...

A 2-yr study using 288 steers each year was conducted to determine the economic effects of sorting and feeding genetically similar cattle in different production systems. Steers were purchased at weaning in November and assigned randomly into sorted or unsorted groups. Unsorted steers were assigned randomly to 1 of 3 production systems: calf-fed steers (enter feedlot after weaning), summer year...

Beef cow-calf efficiency has been a topic of several review and symposium papers. A primary focus of many discussions on beef cowherd efficiency has centered on reproductive success and calf yield per cow, or more simplistically calf weight divided by cow weight. Reproduction and weaning weight are important but research has also demonstrated potential benefit from selecting for metabolic effic...

Despite their production potential and ability to survive on marginal resources in extreme conditions, dromedaries have not been exploited as an important food source. Camels have not been specifically selected for milk production, and genetic improvement has been negligible. High individual variation in milk production both within the population and within breeds provides a good base for selec...

Longevity and lifetime productivity are important factors influencing profitability for the cow-calf producer. Heifers that conceive earlier in the breeding season will calve earlier in the calving season and have a longer interval to rebreeding. Calves born earlier in the calving season will also be older and heavier at weaning. Longevity data were collected on 2,195 heifers from producers in ...

Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA, Department of Pediatrics, Brown University Medical School, Providence, RI 02912, USA, Departments of Medicine and Cell and Developmental Biology, University of Pennsylvania, 954 Biomedical Research Building (BRB) II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA and Depar...

Characters related to production and reproduction were observed on 744 straightbred and F2 calves and their dams produced in a five-breed diallel with Angus, Brahman, Hereford, Holstein and Jersey breeds. These data were analyzed to estimate the effects of these characters on the relationship between weaning weight and calving interval. The model used for analysis of postpartum conception and c...