Project Number: 5364-31000-007-05
Project Type: Reimbursable

Start Date: Feb 01, 2004
End Date: Jan 31, 2009

Objective:
1. Using historical data, determine a) the normal birth weight profile for lambs and calves, and b) estimate the genetic and environmental relationships among lamb/calf birth weight and production measures of the lamb/calf, dam, and progeny. 2. Evaluate the effects of elevated dietary selenium on rapidly proliferating tissues of nutrient restricted, gestating ewe lambs and their offspring.

Approach:
Sheep data for this objective will come from the historical database maintained at the US Sheep Experiment Station (USSES). About 50 years of data are in electronic format and these data consist of records on primarily four sheep breeds: Rambouillet, Columbia, Targhee, and Polypay. Cattle data will come from breed association databases. The project will be conducted in phases. Relative to the objectives, the first phase of this project will involve preliminary evaluation of a sub-sample of data using simple statistics. The resulting information will be used in the second phase to form separate species and breed databases, each containing a population of connected animals for evaluating birth weight effects on production characteristics for each animal and its relatives. Birth weight profiles will be used to divide the records into birth weight classes that range from light to heavy for analysis of birth weight effect on future performance. Both adequate and energy restricted nulliparous ewe lambs will be fed either adequate or elevated dietary selenium prior to conception and throughout pregnancy. Immediately prior to parturition, selected ewes and their fetuses will be killed (captive bolt and exsanguination) and placental, digestive and fetal tissues will be harvested. Tissues will be analyzed for, but not limited to, tissue selenium concentration, digestive, placental and fetal tissue mass, vascularity and angiogenesis estimate (via bromo dioxiuridine), and digestive, placental and fetal tissue DNA, RNA and protein content. The ewe lambs not killed will continue dietary treatments until parturition. Beginning at parturition, offspring weights will be determined at birth and weaning. Once weaned, growth performance of the female offspring will be monitored for approximately 30 days; approximately 50% will be housed and fed individually and the other half will remain within the USSES ewe lamb management routine. Immediately following the performance assessment period, selected lambs from both groups will be killed, and the tissues and analyses previously described will be collected and conducted, respectively. Documents Reimbursable with N. Dakota State U. Log 26105.