Relationship between plasma hormone and metabolite levels and breeding values of bulls¹
1995
Graml, R. | Olbrich-Bludau, A. | Schwab, M. | Schallenberger, E. | Schams, D. | Pirchner, F.
SUMMARY: Blood plasma levels of the hormones bovine growth hormone (bGH), insulin and insulin-like growth factor 1 (IGF-1) and the metabolites glucose, free fatty acids (FFA), urea, creatine and creatinine in 70 bulls (Fleckvieh, Braunvieh, Grauvieh) kept at four AI stations were measured. Plasma determinations were performed on day 1 with normal feeding (N), day 4 after fast (F), and day 5 (R) after realimentation. Fleckvieh bulls had lower bGH but higher IGF-1 levels than Braunvieh bulls; young bulls had lower IGF-1 and insulin but higher glucose levels than mature bulls. The effect of fasting led to higher plasma levels of FFA, urea and creatinine and to lower levels of bGH and IGF-1. Correlations between plasma levels and breeding values for yield of milk, fat and protein were estimated for mature bulls. All three breeding values correlated positively with bGH and negatively with insulin, while correlations with other indicators depended on the feeding status of bulls. Prediction equations for breeding values which were limited to three indicators, included FFA, urea, and creatinine, and the r² values ranged up to 0.32. Validation of these equations, derived from Fleckvieh bulls, on Braunvieh and Grauvieh bulls resulted in correlations of about 0.2. The use of indicators, in addition to information from relatives (dam, full and half-sisters), improves the accuracy of selection of young bulls.
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