Multitrait index selection for maximizing genetic gain in egg type chickens
SANDEEP NARWAL, C.P.MALIK, K.L.RAHEJA AND D.S.DALAL
Department of Animal Breeding, CCS Haryana Agricultural University
The present study was conducted on 765 birds produced from 87 sires of strain H of White Leghorn. The traits included were body weight at 20 weeks of age (BW20), age at first egg (AFE), egg production upto 40 weeks of age (EP40), egg weight at 40 weeks of age (EW40) and clutch size from 31 to 40 weeks of age (CS2). Data were analysed by using Harvey’s least squares technique. Twenty six multitrait selection indices were constructed combining all these traits in all possible combinations considering aggregate genotype of EP40 and EW40 with relative economic value as 1.0 and 0.5, respectively, considering selection intensity as 1.40. Through the application of base index I 1 combining all the five traits, the expected response per generation would be 0.2681g, -0.7441 days, 1.5375 eggs, 2.3763g and 0.0404 eggs in BW40, AFE, EP40, BW20 and CS2, respectively having accuracy of selection (R IH value) as 0.5036 and heritability of index (h 2) as 0.2648. Out of the 26 multitrait indices, I 3 was considered to be the best index since increase in EW40 was more than that in I 1 while other estimates were almost similar in these two indices. Index I 3 was 4-trait index combining EW40, AFE, EP40 and CS2 having R IH value, relative efficiency, relative aggregate genetic gain and heritability of index as 0.5024, 99.76 per cent, 99.76 per cent and 0.2591, respectively. Through the application of this index the expected response per generation would be 0.2798g, -0.7298 days, 1.5089 eggs, 1.9704g and 0.0346 eggs in EW40, AFE, EP40, BW20 and CS2, respectively. This study concludes that I 3 is the index of choice to improve the efficiency of pullets of strain H.