Multi-trait selection indices for improving egg mass in egg type chicken
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Date
2004-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The poultry industry is the fastest growing sector among Indian agriculture sectors and today India occupies 4th and 6th place in the world for egg and broiler production, producing 41 billion eggs and 1000 million broilers every year. The impact of such a massive growth of the poultry production has not been felt by masses because of the population explosion. The per capita availability of 40 eggs and 1 kg meat is far behind the ICMR recommendations and the gap can be bridged by developing superior layers following appropriate breeding strategies. In view of the above, the present study was undertaken to construct and evaluate the multi-trait selection indices for improving egg mass in a pure strain (N) of White Leghorn maintained by a commercial poultry heeding organization. The phenotypic and genetic parameters were estimated in the flock under study. The heritability estimates were found to be low for EM40, EP40, EW40 and ASM, whereas the moderate heritability estimates were reported for BW20 and BW40. The egg mass was having a high positive correlation with egg production while egg weight had lower positive association with egg mass. Thus, selection for egg mass seems to be appropriate for improving both egg number and weight. A total of fifty seven multi-trait selection indices were constructed in different combinations incorporating six, five, four, three and two traits as the selection criteria with the selection objective in all the cases being improvement of egg mass only which comprises the aggregate genotype. The multi-trait selection index (IMT1) including all the six traits was found to be the most desirable with the gain in all the individual traits in favourable direction. Based on the estimates of genetic cost of restriction of different traits, the egg mass was found to the have the highest contribution followed by EW40, EP40, BW20, BW40 and ASM. The direct and correlated responses in performance traits from individual selection of pullets were estimated and on comparing with the best index (IMT1), the selection for 20 week body weight was found to be the most desirable with respect to relative accuracy/ efficiency and gain in individual traits particularly the egg number and egg weight for the population under study.
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