EFFECT OF TEMPERATURE-HUMIDITY INDEX, COLD STRESS INDEX AND DRY PERIOD LENGHT ON BIRTH WEIGHT OF JERSEY CALF

摘要

This research was conducted in order to define the effect of temperature-humidity index, cold stress index and length of dry period on birth weight of calves. In this study, pedigree records of 551 Jersey calves in breeding cow pedigree which were born between 2000 and 2004 in Samsun Karakoy Agriculture Enterprise and temperature humidity index together with cold stress index that were calculated by using climatic data obtained from General Directorate of Meteorology were used. These data were classified as three groups for dry period length, temperature-humidity index, cold stress index. They were classified as THI-1(<70), THI-2 (71-75) and THI-3 (76<) for temperature-humidity index (THI); CSI-1(<832), CSI-2 (833-847) and CSI-3 (947<) for cold-stress index (CSI); DPL-1(<60), DPL-2 (60-90) and DPL-3 (90<) for dry period length (DPL). The means of among treatments differences were significant (P<0.001) for seasons. In respect to birth weight among CSI groups differences were significant. Dry periodx temperature humidity index interaction were significant on calf birth weight (P<0.05). The highest temperature-humidity index and the shortest dry period length were determined decreasing to calf birth weight. As a result, cold stress index negativelyaffected on calf birth weight, when dry period of cows coincide with the winter months. Also, calf birth weight was decrease with increasing of temperature-humidity index and short dry period length.