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Food restriction in sheep: endocrine-metabolic response according to the level of body reserves

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Authors: A. Fernández-Foren, J.A. Abecia, M.I. Vázquez, F. Forcada, I. Sartore, M. Carriquiry, A. Meikle y C. Sosa
Issue: 107-4 (257-271)
Topic: Animal Production
Keywords: body reserves, undernutrition, metabolites, hormones, sheep

The metabolic responses to changes in metabolic status could depend on recent (feeding level) or more ancient (body reserves) metabolic history, a concept termed “metabolic memory”. The aim of this work was to study the metabolic response to food restriction in ewes with different body condition score at the beginning of the experiment (CCi). During the breeding season, 36 Rasa Aragonesa ewes were divided into 2 groups with different BCS: BCS > 2.75 (fat ewes, A, mean ± standard error: 2.9 ± 0.04) and BCS < 2.25 (lean ewes, B, 2.1 ± 0.04). During 20 days, both groups received a diet to supply energy and protein maintain requirements, each group was divided into 2 groups and were fed to provide either 1.5 or 0.5 times the daily maintenance requirements; therefore, the 4 groups were: fat control (AC, n = 9), fat undernourished (AS, n = 10), lean control (BC, n = 9) and lean undernourished (BS, n = 8) ewes. Body weight (BW), glucose, non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), insulin, leptin, and insulin-like growth factor (IGF-I) were determined. BS and AS groups lost weight, BC group gained weight, and AC ewes maintained their BW. Plasma glucose concentration and insulin were higher and NEFA was lower in control ewes. Ewes with high BCS had higher concentrations of insulin and IGF-I, and leptin tended to be higher in these animals. Insulin concentrations were higher in control ewes, while other hormones remained unchanged. Glucose, BHB, insulin and IGF-I profiles were affected by initial BCS and nutritional treatment, as is demonstrated by the significant interaction between these factors and days. Metabolites (glucose and BHB) and metabolic hormones (insulin and IGF-I) concentrations showed a peak at estrus time. In conclusion, it was found that glucose, BHB, insulin and IGF-I profiles respond to undernutrition according to the level of body reserves of the animals at the onset of the nutritional restriction.

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