Evaluation of heterosis and heterosis retention in Bos taurus-Bos indicus crossbred cattle for reproductive and maternal traits in cows

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Title: Evaluation of heterosis and heterosis retention in Bos taurus-Bos indicus crossbred cattle for reproductive and maternal traits in cows
Author: Neufeld Arce, Rodney Oliver
Abstract: Reproductive , maternal and weight traits were analyzed for Angus (A ) , Brahman (B ) , Hereford (H ) , and Nellore (N ) straightbred cows ; F1 NA ; 3 /8N 5 /8A cows ; and four breed composite cows (BANH ) at the McGregor Research Station in Central Texas . Heterosis was estimated for calf crop born (CCB ) (n = 1 ,698 ) , calf crop weaned (CCW ) (n = 1 ,698 ) , calf survival (CS ) (n = 1 ,388 ) , birth weight (BW ) (n = 1380 ) , weaning weight (WW ) (n = 1 ,198 ) , and cow weight at palpation (PWT ) (n = 1 ,929 ) by linear contrasts for cow breed and cow breed group . F1 NA and the quarter breed composite BANH dam group expressed significant (P < 0 .0001 ) heterosis for calf crop born and calf crop weaned . The 3 /8 N 5 /8 Aa produced by matings of 3 /4 A 1 /4 N bulls to NA dams expressed significantly more heterosis for CCB (P < 0 .0001 ) and CCW (P < 0 .01 ) , while the 3 /8 N 5 /8 Ac dams expressed less heterosis than predicted from the dominance model for both traits . For CS the 3 /8 N 5 /8 Aa expressed the same amount of heterosis as predicted from the dominance model of 0 .05 , while the 3 /8 N 5 /8 Ab and 3 /8 N 5 /8 Ac dams expressed less heterosis than predictions based on the dominance model . Heterosis estimates were only significantly higher (P < 0 .10 ) for BANHb dams than expectations from the dominance model . For BW all the BANH cows expressed significant heterosis except for the BANH2 cows which expressed significant (P < 0 .05 ) negative heterosis of -0 .96 kg . Calves out of F1 NA cows were heaviest at weaning with 239 kg . All BANH cows expressed significant (P < 0 .0001 ) heterosis for weaning weight except for the BANHc cows . These heterosis estimates were higher than those expected from the dominance model for BANHb and BANH2 cows , while the heterosis estimate was slightly lower in BANHa cows and similar for BANHc cows . All 3 /8 N 5 /8 A cows expressed less heterosis for WW than prediction from the dominance model . Nellore cows were the heaviest at four years of age with 542 kg . Only the BANHb and BANHc cows expressed significant (P < 0 .05 ) heterosis for PWT . None of the 3 /8 N 5 /8 A cows expressed heterosis for cow weight at palpation . Results from this study showed that heterosis levels expressed by the different crossbred cow types were generally equal or higher to those predicted by the dominance model .
URI: http : / /hdl .handle .net /1969 .1 /4894
Date: 2007-04-25

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Evaluation of heterosis and heterosis retention in Bos taurus-Bos indicus crossbred cattle for reproductive and maternal traits in cows. Available electronically from http : / /hdl .handle .net /1969 .1 /4894 .

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