Resumen

CANAS A, Jhon J et al. Lactation curves in Holstein and BON x Holstein dairy cattle in Colombian high tropic. Rev. Lasallista Investig. [online]. 2009, vol.6, n.1, pp.35-42. ISSN 1794-4449.

Introduction. Changes in milk production in a given time can be graphically represented by using a lactation curve, which allows the characterization of the different production systems. Objective. To estimate lactation curves in Holstein and BON x Holstein cattle by using the Incomplete Gamma model and explain the effects of the genetic group and of some environmental factors on the coefficients of the lactation curve. Materials and methods. 1835 milk production records from the first and second lactations of 23 cows were used. The effects of the race, the birth and the time on the different coefficients estimated from the Incomplete Gamma model and other production and reproduction characteristics of interest were determined. Results. Significant differences among the racial groups were evident for the following characteristics: Initial production, total production, duration of the lactation period, milk production at the peak and in the 33rd week, production per day, post-peak slope, number of weeks with production above 15 litters, calving interval and the milk production per day of calving interval (PConclusion. The coefficients estimated by using the Incomplete Gamma model are highly influenced by the genetic group, the number of births and, in a lower measure, by the weather.

Palabras clave : Cattle; crossbreeding; lactation curves.

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