Alterations of serum vitamin E and vitamin A concentrations of ponies and horses during experimentally induced obesity.

Abstract

Vitamin A, vitamin E and retinol-binding protein 4 (RBP4) are a focus of current obesity research in humans. The impact of body weight (BW) gain on fat-soluble vitamins and its associated parameters in equines has not been previously reported. Ten Shetland ponies and 9 Warmblood horses, all adult geldings, non-obese and healthy, were fed an excessive energy diet for 20&#xa0;months to induce BW gain. Serum &#x3b1;-tocopherol (vitamin E), retinol (vitamin A), retinol-binding protein 4 (RBP4) and retinol/RBP4 ratio were analysed before BW gain induction and at six timepoints during the BW gaining period. The mean (&#xb1;SD) % BW gain achieved during two years of excess energy intake was 29.9&#xa0;&#xb1;&#xa0;19.4% for ponies and 17&#xa0;&#xb1;&#xa0;6.74% for horses. Serum &#x3b1;-tocopherol increased significantly in ponies and horses during excess energy intake and circulating &#x3b1;-tocopherol levels correlated positively with &#x3b1;-tocopherol intake (r&#xa0;=&#xa0;.6; p&#xa0;<&#xa0;.001). Serum retinol concentrations showed variations during the study but without relation to intake. Serum RBP4 decreased at the end of the study. The retinol/RBP4 ratio increased with BW gain without differences between ponies and horses. In comparison with human research, the increase in the retinol/RBP4 ratio was unexpected and needs further elucidation.