Determination of heat stress zone for daily milk yield using carryover heat effect model in Murrah buffaloes.

The objective of the present study was to determine heat stress zones (HSZ) in a year for daily milk yield (DMY) of Murrah buffaloes. Data for the study included 2,67,599 daily milk yield records of 445 Murrah buffaloes sired by 171 bulls as well as climatic parameters, viz. dry bulb temperature (Tdb) and wet bulb (Twb) temperatures spanning over 16 years (2001-2016). The regression analysis of DMY on carryover heat effect indicated that the decline in DMY was significant above the carryover heat effect (CHE) 70. April-November were critical for daily milk yield, and maximum decline in daily milk yield was observed during the month of August in Murrah buffaloes. Therefore, two zones in a year were classified as non-heat stress zone (NHSZ) with CHE < 70 for months December-March and heat stress zone (HSZ) with CHE > 70 during April-November.

Effect of scrotal bifurcation on breeding soundness traits in Beetal bucks during summer season.

Relationship of scrotal bifurcation or splitness with breeding soundness traits was investigated in 15 Beetal bucks (17-20 months of age and 48.72 ± 1.57 kg mean BW). Breeding soundness traits of conjoined/unsplit (n = 6) scrotal bucks was compared with split (n = 9) scrotal bucks having lengthwise > 1 in. bifurcation. Two consecutive semen ejaculations per buck were collected at monthly interval during summer season (April to June 2018) using intact buck as teaser and sexual behavior was simultaneously recorded. Scrotal morphometry parameters, i.e., scrotal circumference, scrotal volume, scrotal skin thickness, testis length, width, and thickness were also recorded. Bucks with split scrotum had relatively more scrotal dimensions (scrotal circumference (P < 0.01), scrotal volume (P < 0.01), testis length (P < 0.01)) than conjoined scrotal bucks. Among various semen attributes, semen volume of first ejaculate (P < 0.01), second ejaculate (P < 0.05), mean semen volume (P < 0.01), total sperm count of first ejaculate, and mean sperm count of both ejaculates were more (P < 0.01) in split scrotal bucks. However, scrotal bifurcation had no influence on sexual behavior of bucks. It is concluded that Beetal bucks with split scrotum had relatively better breeding efficiency traits than conjoined scrotal bucks.

Enhancing milk and fertility performances using selection index developed for Indian Murrah buffaloes.

Selection for genetically superior Murrah buffaloes under Network Project on Buffalo Improvement, India, is presently based on milk yield, and it was observed that even in the absence of any direct selection pressure applied on fertility, there has been a downward trend in fertility associated with the selection for milk yield. The aim of the study was to develop selection indices which include fertility besides milk yield in Murrah buffaloes. Data pertaining to 1,224 lactation records spread over a period of 19 years were recorded and analyzed in the study. The negative association of pregnancy rate (fertility) with a 305-day milk yield (-0.08 ± 0.04) and wet average (-0.12 ± 0.02) indicated the importance of incorporating fertility trait in the construction of selection index. Four types of selection indices were constructed and evaluated. Two indices were developed using expected producing ability 305-days milk yield (EPAMY) with 6.5 and 4% fat in milk along with expected fertilizing ability (EFA). The other two indices developed consist of expected producing ability wet average (EPA WA) and EFA. The index involving (EPA WA and EFA) was found to be a more effective selection criterion in our herd, as the accuracy of index was more (0.61), in comparison to the index involving EPA MY and EFA. The robustness of selection index was assessed by increasing the relative economic values of included traits by 25 and 50%, and accuracy of the index remains almost stable without much change. The developed selection strategy involving EPA WA and EFA should be considered for the genetic evaluation of Murrah buffaloes, as it has a potential for maximizing the lifetime reproduction and production performances of the breed.