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United States Department of Agriculture

Agricultural Research Service

Title: Use of Recombinant Gnrh Antigens for Immunosterilization of Beef Heifers

Authors
item Geary, Thomas
item Grings, Elaine
item Macneil, Michael
item Bellows, Susan
item Bertrand, K - WASHINGTON STATE UNIV
item DE Avila, D - WASHINGTON STATE UNIV
item Reeves, Jerry - WASHINGTON STATE UNIV

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 2001
Publication Date: June 1, 2001
Citation: GEARY, T.W., GRINGS, E.E., MACNEIL, M.D., BELLOWS, S.E., BERTRAND, K.P., DE AVILA, D.M., REEVES, J.J. USE OF RECOMBINANT GNRH ANTIGENS FOR IMMUNOSTERILIZATION OF BEEF HEIFERS. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. 2001. v. 79(Suppl. 1). p. 117.

Interpretive Summary: Beef heifers (n=47) were immunosterilized with a fusion protein consisting of thioredoxin with 7 GnRH peptides (tGnRH), a fusion protein consisting of ovalbumin with 7 GnRH peptides (oGnRH), a cocktail of tGnRH/oGnRH, or a cocktail containing thioredoxin and ovalbumin (control). Primary and booster vaccinations were administered at week 0, 6, and 12. Six heifers within each treatment received Synovex H implants at wk -2. Weekly blood samples were collected to determine serum progesterone concentrations and GnRH antibody titers. GnRH antibody titers increased after the first booster injection, peaked after the second, and remained elevated through the end of the study for GnRH immunized heifers (P<0.01). Heifers that were immunized against oGnRH had greater (P<0.05) GnRH antibody titers than tGnRH heifers but did not differ (P=0.20) from tGnRH/oGnRH heifers. Estrous cycles were suppressed (P<0.05) in 10/12, 12/12, 11/12 and 0/11 tGnRH, oGnRH, tGnRH/oGnRH, and control heifers, respectively. At slaughter, uterovarian weights were lighter (P<0.01) for GnRH immunized heifers than controls. Synovex H implanted heifers had greater ADG from wk 6 to 26 and wk -2 to 26, greater REA, and lower %KPH, yield grade, and quality grade than non-implanted heifers. We conclude that immunization against the tGnRH, oGnRH and tGnRH/oGnRH fusion proteins produced anti- GnRH antibodies that suppressed estrous cycles in 83, 100, and 92% of heifers, respectively, without affecting feedlot or carcass performance. Implanting heifers with Synovex H improved ADG, REA, and yield grade. Protocols that yield greater than 95% estrous suppression may someday replace surgical spaying of heifers.

Technical Abstract: Beef heifers (n=47) were immunosterilized with a fusion protein consisting of thioredoxin with 7 GnRH peptides (tGnRH), a fusion protein consisting of ovalbumin with 7 GnRH peptides (oGnRH), a cocktail of tGnRH/oGnRH, or a cocktail containing thioredoxin and ovalbumin (control). Primary and booster vaccinations were administered at week 0, 6, and 12. Six heifers within each treatment received Synovex H implants at wk -2. Weekly blood samples were collected to determine serum progesterone concentrations and GnRH antibody titers. GnRH antibody titers increased after the first booster injection, peaked after the second, and remained elevated through the end of the study for GnRH immunized heifers (P<0.01). Heifers that were immunized against oGnRH had greater (P<0.05) GnRH antibody titers than tGnRH heifers but did not differ (P=0.20) from tGnRH/oGnRH heifers. Estrous cycles were suppressed (P<0.05) in 10/12, 12/12, 11/12 and 0/11 tGnRH, oGnRH, tGnRH/oGnRH, and control heifers, respectively. At slaughter, uterovarian weights were lighter (P<0.01) for GnRH immunized heifers than controls. Synovex H implanted heifers had greater ADG from wk 6 to 26 and wk -2 to 26, greater REA, and lower %KPH, yield grade, and quality grade than non-implanted heifers. We conclude that immunization against the tGnRH, oGnRH and tGnRH/oGnRH fusion proteins produced anti- GnRH antibodies that suppressed estrous cycles in 83, 100, and 92% of heifers, respectively, without affecting feedlot or carcass performance. Implanting heifers with Synovex H improved ADG, REA, and yield grade. Protocols that yield greater than 95% estrous suppression may someday replace surgical spaying of heifers.

Last Modified: 12/22/2014
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