| Initial body condition score affects hormone and metabolite response to nutritional restriction and repletion in yearling postpubertal beef heifers. | |
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MedLine Citation:
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PMID: 19359502 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Twenty Simmental x Angus, half-sibling, postpubertal heifers (initial BW of 443 +/- 9 kg) were allotted randomly into 2 treatment groups to evaluate if initial BCS affects response of the hypothalamic-pituitary-ovarian axis to metabolic signals elicited by energy restriction and repletion. During a preliminary feeding period, diets were formulated so that each heifer in the designated treatment would reach a BCS of 5 (moderate condition; MOD) or a BCS of 7 (heavy condition; FAT). Once each heifer had reached desired BCS, diets were formulated to supply 30% of NE(m) requirements until each heifer became anestrous (serum concentrations of progesterone < 1 ng/mL; restriction period). Blood collections took place on d 1 of each period, on d 43 of energy restriction and d 44 of energy repletion, and when heifers were confirmed to recommence estrous cycles. When heifers were cycling, their estrous cycles were synchronized to ensure hormone sampling occurred during late diestrus or early proestrus. Energy restriction resulted in decreased concentrations of LH (FAT, P = 0.02; MOD, P < 0.001), IGF-1 (FAT, P < 0.001; MOD, P = 0.003), and insulin (P < 0.001); in contrast, concentrations of GH (P < 0.001) and plasma urea nitrogen (P < 0.001) increased. During repletion, LH concentration increased (P = 0.03) in MOD condition heifers but was still less (P = 0.002) than d 1 of restriction, whereas LH concentration tended to increase in FAT heifers (P = 0.06) until it was similar (P = 0.40) to d 1 of restriction. Repletion also increased concentrations of IGF-1 (P < 0.001), insulin (P < 0.001), and glucose (P < 0.001), whereas concentrations of GH (P < 0.001), NEFA (P < 0.001), and plasma urea nitrogen (P < 0.001) decreased. For both treatments, concentrations of GH after repletion were similar (FAT, P = 0.88; MOD, P = 0.10) to those on d 1 of restriction. After repletion, FAT condition heifers had decreased concentrations of IGF-1 (P < 0.001), insulin (P < 0.05), and glucose (P < 0.001), but greater concentrations of acetate (P < 0.01) and butyrate (P < 0.05), than MOD heifers. Anestrus or resumption of estrous cycles seems to be activated gradually in response to dietary manipulation, unrelated to certain metabolite changes. |
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Authors:
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J M Cassady; T D Maddock; A DiCostanzo; G C Lamb |
Publication Detail:
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Type: Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't Date: 2009-04-09 |
Journal Detail:
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Title: Journal of animal science Volume: 87 ISSN: 1525-3163 ISO Abbreviation: J. Anim. Sci. Publication Date: 2009 Jul |
Date Detail:
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Created Date: 2009-06-16 Completed Date: 2009-09-02 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8003002 Medline TA: J Anim Sci Country: United States |
Other Details:
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Languages: eng Pagination: 2262-73 Citation Subset: IM |
Affiliation:
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St. Paul Beef Cattle Teaching and Research Facility, Department of Animal Science, University of Minnesota, St. Paul, MN 55108, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animal Feed
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analysis Animal Nutritional Physiological Phenomena Animals Body Composition / physiology* Body Weight / physiology Cattle / physiology* Diet / veterinary* Female Growth Hormone / blood Luteinizing Hormone / blood* Nutritional Status / physiology Reproduction Sexual Maturation / physiology |
| Chemical | |
Reg. No./Substance:
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9002-67-9/Luteinizing Hormone; 9002-72-6/Growth Hormone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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