Modulation of gonadal function in bulls and heifers by recombinant hormones or nutritional regimen /
Three experiments were conducted to determine whether gonadal function of bulls and heifers could be positively modulated by nutritional regimen or by two recombinant hormones (bovine somatotropin, RBST, or bovine follicle stimulating hormone, RFSH). In experiment 1, bulls were allotted to either c...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739364251&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Three experiments were conducted to determine whether gonadal function of bulls and heifers could be positively modulated by nutritional regimen or by two recombinant hormones (bovine somatotropin, RBST, or bovine follicle stimulating hormone, RFSH). In experiment 1, bulls were allotted to either confinement (n=27) or pasture (n--26) post-weaning development for 112 d. Mean BW and HH were greater (P<.Ol) for confinement than for pasture bulls. Bulls from the confinement (n-- 1 0) and pasture (n-- 1 0) groups were selected for a breeding study. Mature Salers (n--9) and yearling bulls were joined with cows (n=610) under range conditions for 6.5 mo. Yearling bulls sired fewer calves (P<.OOOI) than did mature bulls, and there was no difference in the number of calves sired by confinement or pasture bulls. In experiment 2, yearling bulls were allotted to a control (n=5) or RBST (n=5) treatment for 56d. Bulls received a biweekly injection of either placebo or rBST to equal .2 mg/kg 75 /day. Mean BW, HH, scrotal circumference and semen quality did not differ between treatments. Smoothed series mean growth hormone (GH) increased over time (P<.05) and was greater (P<.Ol) for RBST versus control bulls at 4, 6, and 8 wk. Maximum and minimum GH concentration and the number of GH peaks were greater (P<.Ol) for RBST than for control bulls. In experiment 3, three cloned and three control heifers were randomly allotted to one of three treatments in Latin Square arrangement. Heifers were treated with RFSH, rFSH+rBST, or FSH-P+rBST. rFSH+rBST treatment resulted in fewer (P<.05) degenerate embryos than the RFSH treatment. The cloned heifers had fewer (P<.05) unfertilized ova and a greater (P<.05) number of good embryos than control heifers. In conclusion, bulls developed in a pasture environment with supplementation can achieve a reproductive rate similar to that of bulls developed in confinement. Administration of RBST for 56 d to peripubertal bulls does not enhance growth rate or testicular development. Response to superstimulation with either FSH-P or RFSH is similar, while the response is enhanced by addition of RBST in the superstimulation regimen. |
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| Item Description: | Vita. "Major Subject: Physiology of Reproduction". |
| Physical Description: | 68-77 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |