Influence of Temperature and Humidity on Pregnancy Rate of Murrah Buffaloes under Subtropical Climate

Abstract

Heat stress has adverse effects on fertility of dairy animals. Decline in fertility is linearly associated with an increase in combination of both temperature and humidity. The purpose of this study was to investigate the relationship between temperature humidity index (THI) and the pregnancy rate of Murrah buffaloes in a subtropical climate. The effects of genetic and non-genetic factors viz., sire, parity, period of calving and age group at first calving were found non-significant on pregnancy rate. The effect of THI was found significant (p<0.001) on pregnancy rate of Murrah buffaloes calved for first time and overall pregnancy rate. The threshold THI affecting the pregnancy rate was identified as THI 75. The months from October to March showed THI<75 and considered as non heat stress zone (NHSZ), while months from April to September were determined as heat stress zone (HSZ) with THI≥75. The lowest overall pregnancy rate (0.25) was obtained in July with THI 80.9, while the highest overall pregnancy rate (0.59) was found in November with THI 66.1. May and June were identified as critical heat stress zone (CHSZ) within the HSZ with maximum decline (−7%) in pregnancy rate with per unit increase in THI. The highest overall pregnancy rate was estimated as 0.45 in NHSZ with THI value 56.7 to 73.2. The pregnancy rate was found to have declined to 0.28 in HSZ with THI 73.5 to 83.7. However, the lowest pregnancy rate was estimated as 0.27 in CHSZ with THI value 80.3 to 81.6.

Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review

“…All these THI models were used in a study conducted by Dash et al . [ 24 ] at Karnal in India. Month wise average THI values with seven different THI models during 20 years from 1993 to 2012 were presented in Figure-1 .…”

“…All these environmental factors are pooled to produce heat stress on animals, which is defined as any combination of environmental variables producing conditions that are higher than the temperature range of the animal’s thermoneutral zone (TNZ) [ 5 ]. Heat stress has an adverse effect on reproduction traits of dairy cattle [ 6 , 7 ] and buffaloes [ 8 ]. The negative influence of heat stress on reproduction traits of cattle and buffaloes can be quantified through formulating temperature humidity index (THI).…”

“…The significant (p≤0.05) decline in the first service pregnancy rate of dairy cattle was observed at THI level above 72 [ 14 ] and heat stress was one of the major factors for a significant reduction in a pregnancy rate of crossbred cows in India [ 15 ]. The buffaloes are also susceptible to heat stress with respect to decline in fertility above THI level 75 in a subtropical climate [ 8 ]. This review was aimed to determine the influence of heat stress in relation with THI on reproductive performances of cattle and buffaloes.…”

Investigation of the Efficiency of CIDR-PG for Dehong Dairy Buffaloes under Thermoneutral and Heat Stress Conditions

“…THI exceeding 72 decreases the growth, milk yield and reproductive performance of buffaloes. Dash et al (2015) reported that the threshold THI for pregnancy rate was identified as 75 in Murrah buffaloes (Dash et al, 2015). Although we cannot determine the threshold THI for pregnancy rate in Dehong dairy buffaloes, the average high THI in summer appeared to restrict their day 90 pregnancy/AI, especially for heifer buffaloes.…”

The Impact of Climate Change on Livestock Production and Reproduction: Ameliorative Management

“…Climate change has a great impact on the reproductive activity of cattle and buffaloes (Dash et al, 2015). …”