Assessment of expected breeding values for fertility traits of Murrah buffaloes under subtropical climate.

A K Chakravarty,K Mahesh Singh,Vaishali Sah,Soumya Dash,Arpan Upadhyay,Pushp Raj Shivahre,Avtar Singh

doi:10.14202/vetworld.2015.320-325

Abstract

Aim:The aim of the present study was to assess the influence of temperature and humidity prevalent under subtropical climate on the breeding values for fertility traits viz. service period (SP), pregnancy rate (PR) and conception rate (CR) of Murrah buffaloes in National Dairy Research Institute (NDRI) herd.Materials and Methods:Fertility data on 1379 records of 581 Murrah buffaloes spread over four lactations and climatic parameters viz. dry bulb temperature and relative humidity (RH) spanned over 20 years (1993-2012) were collected from NDRI and Central Soil and Salinity Research Institute, Karnal, India. Monthly average temperature humidity index (THI) values were estimated. Threshold THI value affecting fertility traits was identified by fixed least-squares model analysis. Three zones of non-heat stress, heat stress and critical heat stress zones were developed in a year. The genetic parameters heritability (h2) and repeatability (r) of each fertility trait were estimated. Genetic evaluation of Murrah buffaloes was performed in each zone with respect to their expected breeding values (EBV) for fertility traits.Results:Effect of THI was found significant (p<0.001) on all fertility traits with threshold THI value identified as 75. Based on THI values, a year was classified into three zones: Non heat stress zone(THI 56.71-73.21), HSZ (THI 75.39-81.60) and critical HSZ (THI 80.27-81.60). The EBVfor SP, PR, CR were estimated as 138.57 days, 0.362 and 69.02% in non-HSZ while in HSZ EBV were found as 139.62 days, 0.358 and 68.81%, respectively. EBV for SP was increased to 140.92 days and for PR and CR, it was declined to 0.357 and 68.71% in critical HSZ.Conclusion:The negative effect of THI was observed on EBV of fertility traits under the non-HSZ and critical HSZ Thus, the influence of THI should be adjusted before estimating the breeding values for fertility traits in Murrah buffaloes.

Highlights

India is the largest producer of milk in the world and buffaloes contribute the highest (56.64%) share to milk production [1]
The negative effect of temperature humidity index (THI) was observed on expected breeding values (EBV) of fertility traits under the non-HSZ and critical HSZ the influence of THI should be adjusted before estimating the breeding values for fertility traits in Murrah buffaloes
The month wise average dry bulb temperature varied from 12.43°C in the month of January to -32.54°C in may while relative humidity (RH) ranged between 42.01% in April and 80.72% in August during the period

Summary

Introduction

India is the largest producer of milk in the world and buffaloes contribute the highest (56.64%) share to milk production [1]. Buffaloes are considered as a triple purpose species producing milk, meat and draft power for agriculture work. One of the most limiting factors in dairy production in the subtropical climate is heat stress. Heat stress is defined as the combination of environmental parameters producing conditions that are higher than the temperature range of animal’s thermal neutral zone [3]. Buffaloes are highly susceptible to heat stress, especially under direct exposure to the sun’s rays since its evaporative cutaneous cooling mechanism is weak due to the presence of low density of sweat glands [4]. Heat stress causes summer anoestrous which hinders the reproductive efficiency

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