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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics, Breeding, and Animal Health Research » Research » Research Project #438711

Research Project: Enhancing Sheep Production Efficiency Through Strategic Use of Genetic and Reproductive Technologies

Location: Genetics, Breeding, and Animal Health Research

Project Number: 3040-31000-100-18-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 1, 2020
End Date: Jul 1, 2021

Objective:
Objective 1: Estimate genetic and non-genetic effects contributing to ewe productivity in accelerated lambing systems. Objective 2: Identify factors that enhance/limit ram fertility in natural and artificial mating. Objective 3: Preserve and increase the genetic diversity of U.S. Romanov flocks.

Approach:
Objective 1: Cooperator has initiated an accelerated lambing program in which ewes are expected to lamb 3 times in 2 years. Historical data collected on the flock will be analyzed to estimate breed, biological, environmental, and genetic effects contributing to ewe productivity in a semi-extensive production system. Objective 2: Several live animal and in-vitro experiments are proposed to determine genetic and non-genetic factors that contribute to ram fertility in natural and artificial mating. Factors contributing to ram breeding capacity in natural mating will be assessed by first exposing single rams to a small group of estrus synchronized ewes for a short duration followed by prolonged exposure to non-synchronized ewes in multiple ram groups. Ram breeding activity, number of ewes successfully mated, and dominance/submissiveness to other rams will be evaluated. Semen will be collected on each ram before and after exposure to ewes to assess sperm characteristics and will contribute to in-vitro experiments thereafter. This evaluation will focus on retention of semen quality after processing for use in liquid semen artificial insemination. The addition of antioxidants (glutathione) and sugars (trehalose) to biological (milk/egg yolk) and chemically defined (tris-based buffers) extenders on sperm viability and motility after cooled overnight shipment to the USDA-ARS National Animal Germplasm Program (Fort Collins, CO) will be assessed. Objective 3: First, DNA and live rams will be acquired from participating U.S. flocks to assess the frequency of economically relevant and yet to be evaluated genetic markers within the U.S. Romanov population. Frozen Romanov semen will be imported from foreign populations to artificially inseminate ewes and resulting progeny will be retained in the flock for future evaluation as breeding animals.