Abstract

A total of 7239 lactations of Caracu cows were used to adjust lactation curves using segmented polynomials with four quadratic segments (4QS). For the average lactation curve the knots were at 2, 26 and 36 weeks of lactation. The parameters were estimated using nonlinear iterative methods (Gauss-Newton). Adjusted coefficient of determination (R2a) and distances between actual and predicted total milk yield (%dTY), as a percentage of the first, were calculated. For the average lactation curve, R2A was 99.96% and the %dTY was 0.01%. For individual lactations, 73.8% of them had R2A higher than 70% and 84% had %dTY within +2%. For some groups of lactations this function showed good adherence.

L. El-Faro, L. G de Albuquerque, L. A Fries

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 23: Opening: plenary; technology; transfer; beef cattle; dairy cattle; pigs., , 411–414, 1998
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