Effects of vitamins A, D3 and E on growth performance and carcass characteristics, and on lipolytic responsiveness and insulin secretion in Japanese black steers
1998
Matsuzaki, M. (Kyushu National Agricultural Experiment Station, Nishigoshi, Kumamoto (Japan)) | Hara, S. | Ogawa, M. | Shiba, N. | tsuneishi, E.
To investigate the effects of restricted vitamins A, D3 and E intake on feeding performance, carcass characteristics, and metabolic and hormonal status, 7 Japanese Black steers (15.2 +- 0.1 months of age) were used in an 11 months feeding trial. Steers had free access to a rice straw and a concentrate either supplemented with (+VIT; n=4) or without (-VIT; n=3) 7,500 IU vitamin A, 1,500 IU vitamin D3 and 7.5 IU vitamin E per 1 kg of the concentrate until slaughtered at 26 months of age. Monthly blood samples were collected to determine plasma concentrations of retinol, metabolites, insulin and insulin-like growth factor-1. Intravenous challenges of nor-epinephrine (NE; 0.01 mg/kg BW) and glucose (0.625 mM/kg BW) were administered separately at the age of 17.21 and 25 months, to asses in vivo lipolytic responsiveness and insulin secretion. After 21 months of age, the -VIT steers had significantly lower plasma retinol levels. Body weights and body weight gain during the experiment tended to be higher in +VIT steers than in -VIT steers, whereas feed intake was not affected by supplemental vitamins. Vitamin supplementation did not affect any of carcass traits including lipid content in M. longissimus thoracis. Although a tendency for elevated plasma cholesterol in the -VIT steers was observed, other metabolite and hormone concentrations and the responses to NE and glucose challenge were not affected by the restriction of vitamins A, D3 and E intake. The restricted vitamins A, D3 and E intake in Japanese Black steers during the period for 15 to 26 months old appeared to be ineffective for improvement of marbling performance
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