Heat tolerance of dairy cows with various Holstein Friesian crossbreds in the Humid Tropic
1996
Rukpunn Wilairat
Study of heat tolerance on dairy cows with various Holstein Friesian crossbreds were carried out at the Dairy Farm of Dairy Promotion Organization, Muaklek. The first experiment involved a study on milk production from the data 751 records of the cows at the farm between 1989-1993. The result revealed that the Holstein Friesian crossbreds did not give a clear cut picture of milk production. The second experiment was focussed on the responses of certain physiological parameters such as respiration rate, rectal temperature, pulse rate, haemoglobin value, hematocrit value and coefficient of tolerance to heat stress including milk production (yield/day) in the cows of 50, 75-87.5 and 90-100 percent Holstein Friesian) blood levels. Total number of cows were used 29 animals, 7 of which were in the 1st lactation while the remainders were in the 2nd lactation. The design of the experiment was the split plot in time. There were no difference in all the physiological parameters between on 75-87.5 and 90-100 percent blood level Holstein Friesian crossbreds (P0.05), whereas the 50 percent blood level Holstein Friesian group was highly significant different from the other groups (P0.01). The heat tolerance of the 50 percent blood level Holstein Friesian group was better than that of the 75-87.5 and 90-100 percent blood level Holstein Friesian groups. The latter groups were not significantly different in heat tolerance. Further more the 50 percent blood level Holstein Friesian group had higher milk yield/day than that of the other groups (P0.01), while there were no difference between milk yield/day of the 75-87.5 and 90-100 percent blood level Holstein Friesian crossbreds. (P0.05).
Mostrar más [+] Menos [-]Palabras clave de AGROVOC
Información bibliográfica
Este registro bibliográfico ha sido proporcionado por Kasetsart University