نبذة مختصرة : The aim of the study was to measure the effect of some environmental factors in the milk production of two Holstein herds in the Chiriquí dairy basin, including milk weighing (PDC) among 1996 and 2016. The environmental temperature was obtained from two weather stations near the herds. A mixed model was applied with sire as a random effect. It was analyzed the effect of herd, age at birth, number of births, temperature and interactions among them on the PDC. The model showed differences (p <.0001) for all the effects included. The average daily production was 22.30 kg / day and 6774.05 kg accumulated at 305 days. The duration of breastfeeding was 349 ± 93 days. The effects of age at birth on daily milk production showed a pattern of sustained increases until six years of age (third birth). Herd one doubled its production while in herd two in which the increases were of the order of 40%. Two thermal zones were identified in relation to maximum temperature, first called tolerance zone where no significant effects in milk production, and another zone called thermal stress (ST) with a regression coefficient -0.268, and 42.6% of the PDC records were measured under ST conditions. It is concluded that the environmental factors evaluated affected milk production and should be considered in genetic evaluation programs for the studied area. ; Para estudiar el efecto de algunos factores ambientales en la producción de leche se dispuso de los pesajes de leche (PDC) de dos rebaños Holstein en la cuenca lechera de Chiriquí que comprendió los años 1996-2016. La temperatura ambiental se obtuvo de dos estaciones meteorológicas próximas a los rebaños. Se aplicó un modelo mixto con el padre como efecto aleatorio. Se analizó la influencia de los efectos de rebaño, edad al parto, número de partos, temperatura e interacciones entre ellos en las PDC. Los resultados mostraron diferencias (p<.0001) para todos los efectos incluidos. La producción diaria promedio fue de 22,30 kg/día y acumulado a 305 días de 6774,05 kg. La duración ...
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