A.A. Sermyagin, V.I. Seltsov
All-Russian Research Institute of Animal Husbandry named after academy member L.K. Ernst, Dubrovitsy, 60, Podolsk destrict, Moscow region, 142132, Russia
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Summary. The models of standard lactation curves for Simmental and Black and White cows were developed for different levels of milk yield from 5000 to 6000 kg and from 7000 to 8000 kg, respectively. In order to optimize the prognosis depending on the age the level of reproduction qualities of cows was considered in lactations: calving interval from 367 to 378 days for Simmental and from 392 to 416 days for Black and White breeds, as well as a persistency of milk yield. The simulation methodology proposed by P.D.P. Wood, T.E. Ali, and L.R. Schaeffer, based on the gamma distribution function and the regression equation was used for the modeling. The models had a different degree of approximation (from R2 = 0.71 to R2 = 0.94) and can be used both for practical application in dairy management (functional model) and also for prediction of lactation activity of animals in order to increase an accuracy of estimated breeding value (regression model). Breeding and genetic parameters of models of lactation curves were studied by two-way analysis of variance. It was revealed the significant effect of the fixed factor of the stud bull on the parameter of the lactation model (ln(a)) by Wood for Simmental and Black and White cows: F = 1.717 and F = 2.356, respectively. It was shown that the highest value of heritability (from 0.087 to 0.218) was in coefficients associated with peak milk yield, maximal daily milk yield and model parameters characterizing the period from calving to lactation peak.
Keywords: lactation curve, lactation peak, maximal daily milk yield, model, milk yield persistency, heritability.
Author Details: A.A. Sermyagin, Cand. Sc. (Agr.), Senior Researcher (e-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); V.I. Seltsov, Cand. Sc. (Agr.), Head of Laboratory.
For citation: Sermyagin A.A., Seltsov V.I. Modelling and evaluation for lactation function of dairy cows. Dostizheniya nauki i tekhniki APK. 2015. T.29. №1. pp. 42-45 (In Russ)