The relationships between the performance of Holstein steers and insulin secretion ability

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This study aims at investigating the relationships between the performance of Holstein steers and insulin secretion ability. Holstein steers at three fattening stage were used to investigate the circadian insulin changes and steers at finishing stage were used to investigate the correlation between characteristics of carcass and plasma insulin concentration. And propionate solution (0.625mmol/kg BW) was intravenously injected. The blood was taken for 24hr or at the time of propionate injection. The plasma was separated and determined for plasma insulin concentration. Finishing steers were slaughtered and carcass was measured and graded. The 9-11th rib-eye was analyzed for moisture and crude fat contents.Plasma insulin concentration of finishing steers was higher than that of middle or latter fattening steers. And insulin secretion ability after propionate injection at finishing stage was higher than that at middle or latter fattening stage. There was a positive correlation between circadian insulin change at 25 month of age and trimming fat percentages, but not significant. Plasma insulin concentration after propionate injection tended to correlate positively with carcass weight, but negatively with meat quality and rib-eye crude fat content.In conclusion, the circadian change of insulin concentration was affected by fat accumulation, and insulin secretion ability after propionate injection was correlated with meat quantity.