IMPROVING FERTILITY OF HEAT-STRESSED DAIRY CATTLE

Recipient Organization
AGRICULTURAL RESEARCH SERVICE
(N/A)
BROOKSVILLE,FL 34605

Performing Department
(N/A)

Non Technical Summary
(N/A)

Animal Health Component

75%

Research Effort Categories

Basic

25%

Applied

75%

Developmental

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
301	3310	1080	17%
304	3310	1020	35%
304	3310	1080	35%
305	3310	1020	13%

Knowledge Area
305 - Animal Physiological Processes; 304 - Animal Genome; 301 - Reproductive Performance of Animals;

Subject Of Investigation
3310 - Beef cattle, live animal;

Field Of Science
1080 - Genetics; 1020 - Physiology;

Goals / Objectives
1)To determine the effects of the introduction of the slick hair gene from Senepol into Holstein cattle. 2)To determine the chromosomal region of the bovine genome harboring the slick hair gene. 3)To characterize the genetic mechanisms for cellular thermotolerance of bovine embryos.

Project Methods
For Obj. 1)Using artificial insemination, produce 100 heifers sired by heterozygous slick-haired 3/4 Holstein x 1/4 Senepol bulls out of Holstein dams (i.e., produce 50 slickand 50 normal-haired heifers). Growth, reproduction, and lactation data, as well as physiological measures of thermotolerance, will be collected through 4 years of age. For Obj. 2)Perform a whole genome, 20cM scan of reference families segregating for the slick hair phenotype transmitted though Senepol lineage; identify the critical region of the bovine genome harboring the gene conferring the slick hair phenotype; and fine map this region to identify genetic markers tightly linked to the slick hair gene. For Obj. 3)Evaluate the effects of breed of embryo (Angus, Brahman, Romosinuano, and Holstein; straightbred and crossbred) and stage of embryo (in vivo and in vitro produced) development on cellular resistance to heat stress using control and heat-shock treatments (in vitro).

Progress 01/01/02 to 12/31/05

Outputs
4d Progress report. This report serves to document research conducted under a reimbursable agreement between ARS and the University of Florida on Improving Fertility of Heat Stressed Dairy Cattle. Additional details of research can be found in the report for the parent project 6619-31630-002-00D Evaluation of Beef Cattle Germplasm for the Subtropics of the United States. The slick hair coat of Senepol cattle has been shown to be beneficial for heat tolerance in the breed. This trait appears to be controlled by a single gene of large effect. In order to identify this gene, a scan of the bovine genome using up to 300 molecular markers is being conducted. Experiments are being undertaken in Senepol-Holstein cattle that are known to be heterozygous for the slick gene. Successful identification of the genes location and a marker closely associated with the slick effect would serve as a test to determine whether an individual has one or two copies of the gene. This would permit beef or dairy producers in the subtropical or tropical regions of the world to improve performance in their cattle by selection of parent stock that will reliably transfer the gene for slick hair to their progeny.

Impacts
(N/A)

Publications

Progress 10/01/03 to 09/30/04

Outputs
4. What were the most significant accomplishments this past year? This report serves to document research conducted under a reimbursable agreement between ARS and the University of Florida on Improving Fertility of Heat Stressed Dairy Cattle. Additional details of research can be found in the report for the parent project 6619-31630-002-00D Evaluation of Beef Cattle Germplasm for the Subtropics of the United States. The slick hair coat of Senepol cattle is beneficial for heat tolerance in the breed. This trait appears to be controlled by a single gene, which would make it a strong candidate for easy incorporation into various populations of cattle to increase heat tolerance. We are conducting molecular experiments using crossbred Senepol - Holstein cattle to identify the location of the gene responsible for slick hair and to develop a test that can be easily used to determine whether an individual has one or two copies of the gene. This would permit beef or dairy producers in the subtropical or tropical regions of the world to improve performance in their cattle by selection of parent stock that will reliably transfer the gene for slick hair to their progeny.

Impacts
(N/A)

Publications