Dairy merit potential in tropical countries: A case for maintaining high levels of heterosis
1999
Talbott, C.W. (North Carolina A&T State Univ., Greensboro, (USA). Dept. of Animal Science) | Chaudhury, M.Z. | McDowell, R.E. | McDaniel, B.T.
The objective of this investigation was to determine the importance of bred additive and heterotic effects on economically important traits of Bos taurus x Bos indicus crosses. Records were collected from 632 Sahiwal and 634 crosses of Sahiwal with Holstein, Jersey, or Swedish Red and White at two Research Farms in Punjab, Pakistan. Heterotic effects were significant and in economically favourable directions for all traits evaluated. Additive effects of Bos taurus were unfavourable or non-yield traits. Based on estimates from the effect of 100% heterosis, Sahiwal crossed with Holstein and Jersey would be expected to produce more per lactation (1400 and 844 kg) and milk per year (1108 and 976 kg) than the mid-parent mean of the Sahiwal and the predication of respective Bos taurus breed. Heterotic effects of F1 Holstein and Jersey crosses reduced days to estrus (47 and 52), days open (86 and 109)m and calving interval (84 and 114 days). In this study, 76% of the F1 Holstein x Sahiwal crosses produced 1650 kg/yr, a criteria for determining minimum productive and reproductive efficiency while, only 26% of the Sahiwal lactations exceeded this level. Results of this study emphasize the importance of developing a breeding strategy that incorporates and maintains high levels of heterosis between Bos taurus and Bos indicus types of maximize milk production and fitness in tropical environments.
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