Isı stresinin süt ineklerinde süt verimi ve fertilite parametreleri üzerine etkisi
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Date
2013
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Sağlık Bilimleri Enstitüsü
Abstract
In recent years, due to global warming, temperature and humidity values have increased. As a result, heat stress occured in cows decreased milk yield and efficiency of calving. In our study, determing the effect of heat stress on fertility and milk yield has been aimed. Material of the study was composed from 238 Holstein breed cows in a commercial dairy farm at Manyas, district of Balıkesir in the Marmara Region. Monthly maximum temperature, monthly minimum temperature, relative humidity and solar radiation values for the years 2009-2012, between April and October, obtained from the General Directorate of State Meteorological Service, were registered to evaluate the impact on milk yield and fertility parameters. The findings indicated that heat stress in cows due to geographical structure and climatic conditions of the region began to effect in the second half of May, intensity increased between June and August and dercreased in September. During period of increasing average temperature, decline in milk yield occured (r = -427, p <0.05), artificial insemination index started to increase (r = -720, p <0.01), and an increase in missed oestrus rate (12%) was determined. Relative humidity value alone performed decrease in milk yield (r = 80, p> 0.05) and did not influence insemination index (r = -267, p> 0.05), but with temperature has been thought to intend by causing an increase in heat-moisture index. With solar radiation, had no effect on milk yield (r = 128, p> 0.05) and artificial insemination index (r = 104, p> 0.05), when combined with temperature and relative humidity values decrease of efficiency were found. Strong negative relationship between artificial insemination index and decreased milk yield was obtained. In accordance of data obtained, declined milk yield, increasing rate of missed estrus and artificial insemination index due to heat stress, caused indirect elevations of decreased pregnancy and calving rate inducing economical reductions were determined.
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fertilite parametreleri, iklim şartları, tohumlama indeksi