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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #75671
Title: FREQUENCIES AND EFFECTS OF ALTERNATIVE DRB3.2 ALLELES OF BOLA FOR HOLSTEINSIN MILK SELECTION AND CONTROL LINES

Author
item Starkenburg, Ryan
item HANSEN, L - UNIV. MINNESOTA, ST. PAUL
item Kehrli Jr, Marcus
item CHESTER-JONES, H - SOUTHERN EXPT STA, MN

Submitted to: Journal of Dairy Science
Publication Type: Research Notes
Publication Acceptance Date: 7/25/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Mastitis is an infection of the mammary gland that affects more than one-half of the dairy cows on over 95% of all dairy farms. On average, the U.S. dairy farmer will lose more than $180 per cow annually. Mastitis is also a legitimate concern to consumers because of potential antibiotic residues as a result of treating cows for mastitis. The main benefit of the work reported here was the application of a genetic identification scheme that identifies variability among cows for mastitis. A potential benefit of this type of research would be less use of antibiotics in cows to treat mastitis through selection of genetically superior breeding stock.

Technical Abstract: Frequencies of alleles at the DRB3.2 locus of the bovine major histocompatibility complex for two genetic lines were compared, and allelic effects on yield and udder health traits were examined. The DRB3.2 genotypes of 186 cows and heifers were determined using DNA extracted from blood samples. The animals were from a designed selection experiment for milk yield. After edits, 173 animals with known alleles remained (54 from a control line, 119 from a selection line for milk yield). A total of 19 alternative DRB3.2 alleles appeared across the two lines, with frequencies ranging from 0.3% to 21.4%. Allelic frequencies differed significantly between the control and selection lines. Alleles 3, 8, 9, 10, 26, and 28 were more frequent in the control line, whereas alleles 16, 24, and 27 were more frequent in the selection line. An animal model was used to estimate gene substitution effects of alternative alleles on milk fat and protein yields, SCS, chronically elevated SCS, acutely elevated SCS, and mastitis incidence. First, second, and third lactations were analyzed separately. Allele 7 was associated with a significant increase in protein yield during first and second lactations, and a significant increase in chronically elevated SCS and acutely elevated SCS during second lactation. Because of conflicting results with other studies and limited numbers of cows, additional research is needed before specific alleles are confirmed to be associated with measures of yield and udder health.