Efeitos do período de serviço corrente e anterior, do período seco e de outros fatores não genéticos sobre a produção de leites de vacas da raça Gir

Abstract

This work, was conducted in order to study the effects of current and previous days open, and days dry, in milk production in 305 days for Gir cows, and verify there are necessary to use multiplicative adjust factors for this effects, in order to evaluated the best genetics parameters. It was used lactation data from EMBRAPA' Dairy Cattle, for progeny test for bulls and cows. The data from current and previous days open had 4.054 lactation, for to days dry data had 10598 lactation. The herds, are classified in two levels of management, high or low in relation of milk yield in a 305 days for cows delivered in a 64 month of age, 2,505.13 kg for days open and 2,413.30 kg for days dry. Verified that, it was not necessary to adjust the effect of days dry (P>0.25). The large period of days dry, and the low milk yield, the data base utilized maybe responsable for this. The current and previous days open had a effect in a milk yield (P<0.01), in a positive relation for days open. The high production of milk was observated when the current days open was equal to 230.9 days, and for previous days open was equal to 222.9 days, and the production was 2,440 and 2,327 kg respectively. After this points the production was stabilized, when the days open are grated the milk production was not increase or the increase was same to zero. There was generated multiplicative adjust factors for current and previous days open, this should be indicated to corrected a milk yield in a 305 days for Gir cows.