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United States Department of Agriculture

Agricultural Research Service

Title: Luteinizing hormone-releasing immunization alters pituitary hormone synthesis and storage in bulls and steers

item Wells, K
item Geary, Thomas
item De Avila, D
item De Avila, J
item Conforti, V
item Ulker, H
item Mclean, D
item Roberts, Andrew - Andy
item Reeves, J

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2007
Publication Date: 7/6/2007
Citation: Wells, K.J., Geary, T.W., De Avila, D.M., De Avila, J., Conforti, V.A., Ulker, H., Mclean, D.J., Roberts, A.J., Reeves, J.J. 2007. Luteinizing hormone-releasing immunization alters pituitary hormone synthesis and storage in bulls and steers. Journal of Animal Science 85(Suppl. 1):450.

Interpretive Summary:

Technical Abstract: Objectives of this study were (1) to determine if trenbolone acetate (TBA) co-administered with LHRH immunization would suppress reproductive function in beef bulls and (2) to examine the effects of LHRH immunization and TBA treatment on pituitary function. To address these objectives 44 Angus x Hereford bull calves (mean BW = 225 ± 2 kg; mean age = 187 ± 6 d) were randomized into eight treatments in a 2 x 2 x 2 factorial experiment, with castration, LHRH immunization, and TBA administration as treatment factors. Calves immunized against LHRH received a primary injection of ovalbumin-LHRH-7 fusion protein on d 0, followed by two booster injections on d 42 and 196. Calves treated with TBA were implanted on d 224. Mean LHRH antibody binding activity in serum increased after each booster for immunized calves, but was negligible in non-immunized animals throughout the experiment. Concentrations of testosterone in serum were lower (P < 0.0001) by d 84 and scrotal circumference smaller (P < 0.05) by d 168 in LHRH immunized bulls compared to non-immunized bulls. Treatment with TBA tended (P = 0.07) to decrease concentrations of testosterone in serum from bulls. Testes + epididymides weights at slaughter (d 272) were lighter (P < 0.0001) for immunized compared to non-immunized bulls. Both LHRH immunization and castration resulted in decreased anterior pituitary stores of LH and FSH (P < 0.001). Immunization against LHRH suppressed expression of the LH ', and common '-subunit genes (P < 0.0001), while castration increased expression of the same two genes (P = 0.02). Synthesis and storage of LH and FSH, as measured by pituitary LH and FSH content and expression of the LH '-subunit and common '-subunit genes, was suppressed by LHRH immunization.

Last Modified: 10/15/2017
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