Genetic evaluation of Gir bulls under associated herd progeny testing programme

Present address: 1Principal Scientist (usinghas@gmail.com), 2Senior Scientist (venkatesanraja09@gmail.com), 3Scientist (rfq_rahman@yahoo.co.in). 4Research Scientist (ksm1994 @jau.in), Junagadh Agricultural University, Junagadh, Gujarat. Gir is one of the important cattle breeds of India known for its comparatively higher milk production, better resistance to most of the tropical diseases, and ability to survive under poor nutrition and extreme climatic conditions prevalent in its native tract (Gaur et al. 2003). Considering the importance of indigenous cattle breeds, efforts are being taken by ICAR for their genetic improvement through All India Coordinated Research Project (AICRP) on Cattle. Gir breed of cattle is one among the 3 important cattle breeds included under the Indigenous Breeds Project (CIRC Annual Report 2016–17). The project is coordinated by ICAR-CIRC, Meerut in collaboration with the Junagadh Agricultural University, Junagadh, Gujarat. Under this programme, Cattle Breeding Farm, Junagadh has been identified as bull mother or germplasm unit from which the young bulls born to elite females are identified as bulls for progeny testing. The farmer’s herds, Gaushalas and herds maintained by NGOs are utilized as data recording units where the semen of young bulls is used for insemination of Gir animals. Evaluation of breeding bulls is highly essential for selection and dissemination of genetically superior germplasm to improve the milk production. Small herd size, lack of large commercial cattle herds and lack of proper recording system are the major limiting factors preventing the evaluation of breeding bulls extensively. These difficulties are overcome by the concept of associated herd progeny testing programme under which the bulls are evaluated utilizing large number of farmers’ herds as field units so as to get enough number of daughter records for testing. Since no scientific studies have been reported so far on the genetic evaluation of Gir bulls through associated herd progeny testing programme, the present study was conducted to predict the expected breeding value (EBV) of the bulls by best linear unbiased prediction method utilizing the first lactation 305-days milk records of daughters. For the study, information on 222 Gir cows born to six sires of first set, calved during 2013–17 and maintained under different data recording units of the project were utilized. The basic information on pedigree of Gir animals was collected. Fortnightly milk records collected at 15 days interval were utilized to predict the first lactation 305-days milk yield. Abnormal records, viz. abortion, stillbirth, mastitis etc. were excluded from the study. Information on animals having incomplete lactation records due to early disposal was also excluded. Finally, animals having lactation length more than 100 days and milk yield above 800 kg were included in the analysis. The home tract of the Gir breed is the Gir hills and Kathiawar forest and presently the Gir cattle population is concentrated in Junagadh, Porbander, Amreli and Bhavnagar districts of Gujarat. The home tract of Gir breed lies between 20°5’ and 22°6’ north latitude and 70° and 72° east latitude (Gaur et al. 2003). The breeding tract lies about 400 meters above MSL with a range of 125–600 meters and enjoys the typical tropical climatic conditions. Based on agro-climatic conditions of the region, the whole year was divided into three seasons, viz. summer (March–June), monsoon (July–October) and winter (November–February) as reported by Dangar and Vataliya (2014). The information on centre, year and season of calving were utilized to generate the herd-year-season (HYS) effect which was considered as fixed effect while the effect of sire was considered as random. For sire evaluation, bulls having 5 and more daughters were only included. The expected breeding values (EBV) of bulls were estimated by best linear unbiased prediction (BLUP) method as given by Henderson (1973, 1975) using the LSMLMW Model VIII (Harvey 1990). The general model of BLUP estimation was considered as follows: