Reciprocal cross differences in Brahman-Hereford F2 cows: reproductive and maternal traits

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Title: Reciprocal cross differences in Brahman-Hereford F2 cows: reproductive and maternal traits
Author: Wright, Bradley Allen
Abstract: Data from 75 F2 Brahman -Hereford cows of four specific breed combinations , F2 HB (produced by F1 HB sires x F1 HB dams , where ? ? ? ? ? ?HB ? ? ? ? ? ? refers to cattle sired by Hereford bulls and out of Brahman cows ) , F2 BH (produced by F1 BH sires x F1 BH dams ) , HB x BH and BH x HB , were evaluated for maternal performance at the Texas A &M Research Center near McGregor . Differences between breed combinations were analyzed for calf crop born (CCB ) , calf crop weaned (CCW ) , calf survival (CS ) , birth weight (BW ) , weaning weight (WW ) , and cow weight at palpation (PW ) . The adjusted means for F2 HB , F2 BH , HB x BH , and BH x HB were 0 .84 ? ? ? ? 0 .06 , 0 .57 ? ? ? ? 0 .07 , 0 .82 ? ? ? ? 0 .06 , and 0 .62 ? ? ? ? 0 .08 , respectively , for CCW . F2 HB cows had a 0 .27 ? ? ? ? 0 .09 higher percent calf crop weaned than F2 BH cows (P < 0 .01 ) and a 0 .22 ? ? ? ? 0 .11 higher percent calf crop weaned than BH x HB cows (P < 0 .05 ) . HB x BH cows had a 0 .25 ? ? ? ? 0 .08 higher percent calf crop weaned than F2 BH (P < 0 .01 ) and a 0 .20 ? ? ? ? 0 .10 higher percent calf crop weaned than BH x HB cows (P < 0 .05 ) . As 6 -year -olds , the adjusted means for cow weight at palpation for F2 HB , F2 BH , HB x BH , and BH x HB cows were 523 .65 ? ? ? ? 20 .49 kg , 602 .61 ? ? ? ? 23 .63 kg , 492 .84 ? ? ? ? 16 .98 kg , and 515 .93 ? ? ? ? 22 .96 kg , respectively . Averaged across all ages , HB x BH cows weighed 56 .59 ? ? ? ? 15 .29 kg less than F2 BH cows (P < 0 .001 ) and 41 .11 ? ? ? ? 18 .92 kg less than BH x HB cows (P < 0 .05 ) . Also , F2 HB cows weighed 40 .45 ? ? ? ? 17 .68 kg less than F2 BH cows (P < 0 .05 ) . In this herd , HB -sired cows had higher reproductive efficiency than BH -sired cows . Also , HB -sired cows tended to be lighter than BH -sired cows . Although these differences existed , exact causes could not be determined primarily due to confounding between the birth year of the cow and the sire breed of the cow .
URI: http : / /hdl .handle .net /1969 .1 /4978
Date: 2007-04-25

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Reciprocal cross differences in Brahman-Hereford F2 cows: reproductive and maternal traits. Available electronically from http : / /hdl .handle .net /1969 .1 /4978 .

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