Heterosis and Breed Maternal and Transmitted Effects in Beef Cattle II. Growth Rate and Puberty in Females237

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Abstract
Data were analyzed on 200-day weight, average daily gain (ADG) from 200 to 400 days, 400-day weight, ADG from 400 to 550 days, 550-day weight, 550-day hip height, weight at puberty, age at puberty and percentage pregnant at 550 days on 536 females produced in 1973 and 1974 in a four-breed diallel crossing design including Red Poll, Brown Swiss (European and domestic), Hereford and Angus breeds to estimate heterosis and breed maternal and transmitted effects on major economic traits of beef cattle. Effects of heterosis were not significant for 200-day weight but were significant for ADG from 200 to 400 days, 400-day weight and 550-day weight. Most of the effects of heterosis on growth rate were expressed on ADG from 200 to 400 days. Crossbreds were 6.8 kg heavier (P<.05) and 9.4 days younger (P<.10) at puberty than the purebreds. Generally, the Red Poll breed showed a lower breed mean heterosis () for growth traits than the three other breeds in crosses. Breed maternal effects () showed the Brown Swiss and Red Poll breeds superior to the Hereford and Angus breeds in most traits evaluated. Reciprocal differences averaged 33.4, 31.5 and 27.8 kg (P<.01) for 200-, 400-and 550-day weight, respectively, in favor of the females with the Red Poll and Brown Swiss dams in crosses with Hereford and Angus. The Brown Swiss breed showed significantly higher breed transmitted effects () for growth traits than the three other breeds. Red Poll, Hereford and Angus breeds did not differ greatly from each other in for growth traits with differences (P<.05) generally favoring the Angus breed; however, giI for weight at puberty showed the Red Poll breed reaching puberty at a significantly lighter weight than the three other breeds. The Brown Swiss breed in crosses was significantly heavier at 200, 400 and 550 days than the three other breeds in crosses. In crosses, the Red Poll, Hereford and Angus breeds did not differ (P>.05) in 550-day weight, or weight at puberty; but, Red Poll and Angus crosses reached puberty at significantly younger ages than Hereford crosses. The Brown Swiss breed in crosses was significantly heavier than Hereford and Red Poll breeds in crosses when puberty was observed, but it reached puberty at a significantly younger age than the three other breeds in crosses. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.

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