Evaluacion de parametros productivos y determinacion de causales de eliminacion en los rebanos lecheros de los predios Santa Rosa y Vista Alegre.
1992
Valencia B Victor Hugo
The present work was carried out by using the available information concerning the productive and reproductive performance recorded on individual-record cards of cows belonging to the dairy herds of the Universidad Austral de Chile. This study had the following objectives: 1) to obtain productive parameters (production per lactation, lactation duration, real production, production corrected for 305 days and its evolution, and age at first calving); 2) to compute reproductive parameters (interparturition span, coital index, parturition-first service span and parturition-pregnancy span); and 3) to determine the causes of disposal (incidence, percentage and evolution of disposal in different years). All of these studies were made with the information gathered from 1978 through 1990, recording a total of 1,323 lactations. In order to achieve these goals, an analysis of the record cards of each cow during the twelve-year study, was made; it gave information relating to production per lactation, lactation duration, calving date, calving number, insemination date, etc., and also relating the cause and date of culling. As a result of this work, it was concluded that the average production per lactation has increased from 3,816 kg in 1978 to 5,962 kg in 1990; the lactation duration has experienced no changes attributable to time; the average age at first calving has ranged from 28 to 33 months, with a slight trend to decrease as years go by; and the reproductive parameters are within acceptable values and have evolved positively in time, reaching on occasion optimal levels. In this study, the most observed culling cause corresponded to reproductive problems with 18.6%. Culling of cows was made at an average age of 6.96 years, with an average productive life of 4.14 years and 3.16 calvings.
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