Plasma growth hormone, insulin-like growth factor, insulin, and thyroid hormone association with body protein and fat accretion in steers undergoing compensatory gain after dietary energy restriction2
| Autor: | J. M. Hayden, Robert J. Collier, J. E. Williams |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
medicine.medical_specialty
Triiodothyronine Insulin medicine.medical_treatment Thyroid Endogeny General Medicine Reverse triiodothyronine Insulin-like growth factor chemistry.chemical_compound NEFA Endocrinology medicine.anatomical_structure chemistry Internal medicine Genetics medicine Animal Science and Zoology Food Science Hormone |
| Zdroj: | Journal of Animal Science. 71:3327-3338 |
| ISSN: | 1525-3163 0021-8812 |
| DOI: | 10.2527/1993.71123327x |
| Popis: | Eighteen Chianina crossbred steers were used to examine the interrelationship between hormonal status and empty body protein (EBPRT) and fat (EBFAT) accretion during an 88-d controlled realimentation (REAL; DMI was adjusted weekly on an individual BW basis) period. Body composition was determined by monitoring endogenous whole-body 40[K]. At the end of restriction (REST) and on d 31 and 59 of REAL blood samples were taken and analyzed for concentrations of growth hormone (GH), IGF-I, IGF-II, insulin (INS), thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), nonesterified fatty acids (NEFA), glucose, and urea nitrogen. Depositions of EBPRT and EBFAT were decreased (P < .001) in REST (92 d) animals compared with nonrestricted (NR) controls. During REST, plasma levels of glucose, IGF-I, INS, T4, T3, and rT3 were decreased (P < .05); plasma urea nitrogen (PUN), NEFA, and GH levels were increased (P < .05), and IGF-II concentrations were similar between REST and NR steers. A transient compensatory response in BW gain and protein deposition occurred in repleted steers between d 35 and 62 of REAL. During this period, PUN levels markedly declined (P < .01) in REAL steers and glucose concentration increased (P < .01) to levels similar to those in NR controls. This response prevailed even though apparent digestible nutrients were decreased in repleted animals. During energy repletion, plasma levels of T4, T3, rT3, IGF-I, and INS were positively, and of GH was negatively, correlated with EBPRT and EBFAT gain in repleted animals. Unlike IGF-I, IGF-II was not correlated with compensatory body growth. These results suggest that compensating steers are more metabolically efficient; rapid body tissue gain occurs during a period of reduced nutrient digestibility. Additionally, plasma levels of IGF-I, GH, INS, and thyroid hormones, but not of IGF-II, are markedly affected by alteration of energy intake and are highly correlated with empty body gain and protein deposition in compensating late-maturing steers. |
| Databáze: | OpenAIRE |
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