To determine the effects of Beta carotene (B) on reproduction and to define better the role of metabolic hormones during early lactation, seventy-eight Holsteins were alternately assigned at calving to either supplementation with 600 mg synthetic B daily (BC) from day 30 through day 90 of lactation or be controls (C). Cows were fed a basic corn silage complete ration. Biweekly jugular blood samples were analyzed for plasma B, luteinizing hormone (LH), progesterone (P), insulin (I), and glucagon (G). Plasma Bin BC reached a peak of 2.45 ug/ml while that in C reached 1.50 ug/ml. Supplementation significantly increased plasma B in BC (p<.01), but had no effect on plasma LH, P, I, or G or the reproductive parameters measured. Days to first heat, days to first breeding, days open, and services per conception averaged 74, 74, 95, 1.7 in BC and 64, 76, 102, and 1.9 in C. In another experiment 20 Holsteins were assigned at calving based on milk production and the presence of a postpartum heat between days 35 and 60 to be supplemented either with B as in Experiment I or to act as controls. The cows were further divided into high (>41 kg milk/day) and low (27 to 36 kg/day) milk production groups. On day 10 post-estrus cows were cannulated, blood sampled, and challenged with HCG to assess B's specific role in corpus luteum function. Plasma was analyzed for P and LH and reproductive parameters were recorded as in Experiment I. Treatment and milk production effects were not significant for plasma P and LH responses. Linear, quadratic, and cubic regressions of LH on sampling time, Pon sampling time within treatment, and both P and LH on sampling time within production were significant (p<.05) Subtle differences were found in CL response to HCG injection which suggested possible alterations in endocrine function due to B treatment and milk production. / M.S.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/118339 |
| Date | January 1983 |
| Creators | Bindas, Elizabeth Mary |
| Contributors | Dairy Science |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | x, 119 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 09855845 |
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