Year: 2019 | Month: December | Volume 9 | Issue 3
Seasonal Variations in Reproductive Performance of Crossbred Cows in Kerala and the Influence of Climatic Stress Factors over a Period of Six Years
DOI:10.30954/2277-3371.03.2019.3
Abstract:
Affection of the reproductive performance forms early indicator of the influence of adverse environment on physiological processes. Comparing fertility parameters with climatic variables over the years helps to understand the impact, magnitude and determinants of climate change on animal system. Objective of the present study was to assess the yearly and seasonal variations in reproductive performance of crossbred cows, and the influence of thermal stress factors over a period of past six years. Retrospective data collected from farm records and climatic data were analysed using SPSS software. Climatic parameters such as maximum and minimum temperature, relative humidity and THI showed highly significant (P<0.001) seasonal variation. THI was consistently high at a level for causing mild to moderate stress all over the years. However, fertility parameters did not show significant variation across seasons. Between years, fertility parameters varied significantly and climatic variables did not. No significant correlation was found between fertility parameters and climatic variables across seasons, even though time series analysis showed significant correlation between these parameters. In spite of significant variation of climatic variables between seasons and fertility parameters between years, lack of significant seasonal variation of the fertility parameters appears to be due to the inconsistency of seasonal pattern between the years. To conclude, no obvious interrelationship between climatic variables and fertility parameters was evident between seasons, even though THI values were beyond the level of thermal comfort for dairy cattle and is attributed to the adaptation of animals to changing climate through continuous rearing at the same place, and passive selection over the years.
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