Arpan Upadhyay

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

Heat stress has adverse effects on the reproductive performances of dairy cattle and buffaloes. The dairy sector is a more vulnerable to global warming and climate change. The temperature humidity index (THI) is the widely used index to measure the magnitude of heat stress in animals. The objective of this paper was to assess the decline in performances of reproductive traits such as service period, conception rate and pregnancy rate of dairy cattle and buffaloes with respect to increase in THI. The review stated that service period in cattle is affected by season of calving for which cows calved in summer had the longest service period. The conception rate and pregnancy rate in dairy cattle were found decreased above THI 72 while a significant decline in reproductive performances of buffaloes was observed above threshold THI 75. The non-heat stress zone (HSZ) (October to March) is favorable for optimum reproductive performance, while fertility is depressed in HSZ (April to September) and critical HSZ (CHSZ) (May and June). Heat stress in animals has been associated with reduced fertility through its deleterious impact on oocyte maturation and early embryo development. The management strategies viz., nutrition modification, environment modification and timed artificial insemination protocol are to be strictly operated to ameliorate the adverse effects of heat stress in cattle and buffaloes during CHSZ to improve their fertility. The identification of genes associated with heat tolerance, its incorporation into breeding program and the inclusion of THI covariate effects in selection index should be targeted for genetic evaluation of dairy animals in the hot climate.

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

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.

Conventional and fluorescent based semen quality assessment in Karan Fries bulls.

Aim: The present study was carried out on semen ejaculates of 15 Karan Fries (KF) bulls maintained at Artificial Breeding Research Centre, National Dairy Research Institute, Karnal, India with an objective to evaluate the relationship between the conventional and fluorescent based semen quality analysis of the bulls. Materials and Methods: A total of 96 ejaculates were collected from 15 KF (Holstein Friesian [HF] crossbred) bulls. Semen were evaluated for color, volume, mass activity (MA) and percentage of individual motility (IM), sperm concentration, percent live spermatozoa, hypo-osmotic swelling test and acrosome integrity, chromatin integrity, sperm viability, and membrane integrity. Data were analyzed using SPSS software package for descriptive analysis. The correlation between rankings of sires based on conventional and fluorescent semen parameters were calculated by Spearman’s rank correlation coefficient. Results: The average ejaculates volume (ml), sperm concentration (106/ml), MA, IM (%), live (%), morphological abnormalities (%), host (%), acrosome integrity (%), chromomycin A3 (CMA3) (%), SYBR-PI (%), and fluorescent isothiocyanate-peanut agglutinin (FITC-PNA) (%) were 4.57±0.36, 1162.98±97.93, 2.95±0.09, 60.8±1.22, 71.41±2.10, 9.31±1.15, 65.5±1.81, 86.6±1.59, 3.53±0.43, 65.39±2.23 and 74.47±2.53, respectively. Rank correlations were found to be significant for SYBR-PI and FITC-PNA with most of the parameters evaluated by conventional methods. Overall, among conventional criteria, IM revealed ranking of bulls almost similar to that of fluorescent criteria. Conclusion: Overview of our results indicated that, among conventional criteria, MA and IM revealed ranking of bulls almost similar to that of fluorescent criteria.