Identifying the future needs for long-term USDA efforts in agricultural animal genomics.

Agricultural animal research has been immensely successful over the past century in developing technology and methodologies that have dramatically enhanced production efficiency of the beef, dairy, swine, poultry, sheep, and aquaculture industries. In the past two decades, molecular biology has changed the face of agricultural animal research, primarily in the arena of genomics and the relatively new offshoot areas of functional genomics, proteomics, transcriptomics, metabolomics and metagenomics. Publication of genetic and physical genome maps in the past 15 years has given rise to the possibility of being able finally to understand the molecular nature of the genetic component of phenotypic variation.

Effect of excess degradable intake protein on early embryonic development, ovarian steroids, and blood urea nitrogen on days 2, 3, 4, and 5 of the estrous cycle in mature ewes.

Two trials were conducted to determine whether feeding excess degradable intake protein (DIP) during a synchronized estrous cycle and the first 5 d after breeding alters early embryonic development, ovarian steroids, or BUN concentrations in ewes. Ewes were group-fed in Trial 1 (T1) and individually fed in Trial 2 (T2) either 100 (control; T1, n = 15; T2, n = 12) or 200% (high-protein; T1, n = 16; T2, n = 12) of the NRC protein recommendation for maintenance during a synchronized estrous cycle until surgery in the next cycle. Ampullae (AMP), isthmi (IST), and uterine horns (UT) of high-protein and control ewes were removed on d 2 (T1), 3 (T2), 4 (T1), or 5 (T2) after breeding.

Histomorphology, oLH and hCG receptors, and testosterone secretion in vitro in Rambouillet rams from lines in which females had been selected for low or high reproductive rate.

The objective of this study was to determine whether gross or histomorphological components of the testes, capacity and dissociation constants (Kd) of testicular oLH and hCG receptors, and gonadotrophin-stimulated testosterone secretion in vitro differed among Rambouillet rams from lines selected for low or high female reproductive rate and from rams of a random-bred control line. Lines had been selected for approximately 20 years. Data were collected from 22-month-old rams during the late breeding season.

Correcting bias from the standard linear adjustment of weaning weight to an age-constant basis for beef calves.

Standard linear adjustment of weaning weight to a constant age has been shown to introduce bias in the adjusted weight due to nonlinear growth from birth to weaning of beef calves. Ten years of field records from the five strains of Beefbooster Cattle Alberta Ltd. seed stock herds were used to investigate the use of correction factors to adjust standard 180-d weight (WT180) for this bias.

Ovulation rate, lambing rate, litter size and embryo survival of Rambouillet sheep selected for high and low reproductive rate.

Ewes from lines selected for high and low reproductive rate and a control line bred and selected randomly were endoscopically examined 3 to 5 d after breeding to determine ovulation rates in the fall of 1985, 1986 and 1987. Fertility (ewes lambing per ewe exposed), lambing rate (lambs born per ewe exposed) and litter size (lambs born per ewe lambing) were evaluated at lambing in the spring of each year. Embryonic survival was estimated as the number of lambs born per corpora lutea.