The effect of body condition score on blood metabolites and hormonal profiles in ewes

Abstract

The study was designed to investigate the effect of body condition score (BCS) on blood metabolites and hormones in order to assess the nutritional status and to identify which of those metabolites could be used as indicators for determining the nutritional status in ewes. Blood sampling and nitrogen balances were performed in four groups of five mature, dry and non-pregnant ewes with a different BCS namely: 1.25, 2, 3 or 4. Serum concentrations of insulin, non-esterified fatty acids, β-hydroxybutyrate, triglycerides, total lipids, albumin, globulins, total protein, urea, creatinine, insulin-like growth factor-I, and plasma glucose, glucagon, triiodothyronine, and thyroxine concentrations were determined. Results demonstrate a variation in metabolic status at the different BCSs. Undernutrition was more evident in the animals with a BCS of 1.25 but also in those with a BCS of 2. Ewes recorded lower plasma glucose, triiodothyronine and thyroxine concentrations and serum insulin, albumin, globulins, and insulin-like growth factor-I and higher serum non-esterified fatty acids, urea and creatinine. Overnutrition was obvious in ewes with a BCS of 4, reflected by high insulin, glucagon and urea levels. The BCS of 3 represented a more balanced metabolic status, as reflected by intermediate plasma glucose and glucagon, and serum insulin, albumin and globulins concentrations, and low values of urea and creatinine. The stabilization of body weight and BCS at 1.25, 2, 3 and 4 occurred at nutritional levels corresponding to 30, 60, 100 and 120% of the theoretical energy requirements for maintenance. This metabolic characterization clearly demonstrated that the BCS of ewes has a significant effect on metabolites and hormonal profiles. Ewes deal successfully with extreme nutritional conditions although a BCS of 3 appear to be ideal to assure nutritional and metabolic welfare and with a BCS below 2 or above 3 ewes seem more susceptibility to metabolic imbalances. From the variables tested as metabolic indicators glucose, non-esterified fatty acids and insulin provided the more reliable information for the diagnosis of the ewe's energy status and albumin and urea of the protein status.