Heterosis from Crosses among British Breeds of Beef Cattle: Fertility and Calf Performance to Weaning

Section: Resultssupporting

confidence: 81%

Individual and Maternal Additive and Heterotic Effects on 205-Day Weight in Beef Cattle

MacNeil

Dinkel

VanVleck

1982

“…General combining ability and maternal effects were nonsignificant for EBW. Gaines et al (1966) found some evidence for heterosis in birth weights of two-way beef breed crosses but little, if any, evidence of maternal influence, which is consistent with results reported here. Comparison of the reciprocal crossbreds with the mid-parent mean show crossbreds 0.27 kg heavier at birth.…”

Section: Resultssupporting

confidence: 89%

Genetic Factors and Hormonal Stimulation Affecting Weight and Fertility of Ewe Lambs

Bogart

1973

O NE hundred seventy-nine ewe lambs from a three-breed polyallel cross involving the Willamette, Suffolk and Hampshire breeds were used to study the genetic aspects of fertility. Ewe birth weight, ewe weight at mating and fertility were analyzed in relation to heterosis, general combining ability, maternal effect, reciprocal differences, and the effects of a hormone treatment. Treatment consisted of three injections of anterior pituitary extract 2 weeks apart beginning 7 weeks before the breeding period. One-half of the ewes from each breed group were treated, others were not. There was no significant difference in fertility of the treated and control ewes. In some cases, treatment adversely affected fertility, in particular in ewe lambs of the Suffolk breed. Willamette and Hampshire ewes were unaffected.For ewe birth weight, heterotic effects approached significance (P~0.10) and accounted for 2.8% of the total variance in birth weight. Comparisons of reciprocal crossbreds with the mid-parent mean showed crossbreds 0.3 kg heavier at birth.Heterosis, purebred differences and reciprocal differences were highly significant for ewe weight at mating. Maternal effect and general combining ability were significant. Crossbred ewes were 2.5 kg heavier than the purebreds. The genetic factors measured for ewe weight at mating accounted for over 62% of the total variance.Ewe lambs treated with gonadotropins during the normal breeding season do not respond with the success that has been shown for mature ewes. Overall lambing percent was 71 based on the number of lambs born to 179

“…In this study, a higher percentage of cows out of A dams weaned a calf than did cows out of H dams. Gaines et al (1966) and Wiltbank et al (1967) found no differences in A-H reciprocal crosses and Shorthorn x A and Shorthorn x H crosses. Turner et al (1968) likewise found no differences among 1/2 A and 1/2 H dams sired by B, H, A, and Brangus.…”

Section: Resultsmentioning

confidence: 82%

Comparison of crossbred cows containing various proportions of Brahman in spring- or fall-calving systems: IV. Effects of genotype × environment interaction on lifetime productivity of young cows

McCarter

Buchanan

Frahm

1991

Lifetime productivity of young (2 to 6-yr-old) crossbred cows containing various proportions (0, 1/4, or 1/2) of Braham breeding was evaluated using 188 spring-calving and 154 fall-calving cows. Cows were mated to Limousin sires to produce 1983 through 1986 calf crops. The 1987 calf crops were produced using Limousin and Salers sires. Significant (P less than .10) genotype (crossbred cow group) x environment (season of calving) interactions were found for age at first calf and lifetime calving percentage and mature cow weight. Within the spring calving group, no differences were found between crossbred groups for age at first calf or lifetime calving percentage. However, within the fall-calving group, 0 and 1/2 Braham cows from Angus dams calved earlier than did those from Hereford dams. Age at first calf also tended to increase as proportion of Brahman increased in the fall-calving group. Within the fall-calving group, lifetime calving percentage for 0 and 1/2 Brahman cows from Hereford dams was lower than for those from Angus dams. The opposite was true for the 1/4 Braham crosses. In general, as the proportion of Brahman breeding increased, productivity, measured as weight per calf or weight weaned per year, increased; however, age at first calving increased also as proportion of Brahman increased. All spring-calving groups calved earlier in life (P less than .05) than their respective fall-calving counterparts and with the exception of the 0 Brahman groups, which were similar, spring-calving groups produced a higher (P less than .05) percentage of calves than did the fall groups.(ABSTRACT TRUNCATED AT 250 WORDS)