Experimental Results on Crossbreeding Cattle for Beef Production
01 May 1970-Journal of Animal Science (The American Society of Animal Science)-Vol. 30, Iss: 5, pp 694-705
About: This article is published in Journal of Animal Science.The article was published on 1970-05-01. It has received 95 citations till now. The article focuses on the topics: Beef cattle & Shorthorn.
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TL;DR: Results based on both experimentation and computer simulation indicate that differences in additive genetic merit of breeds for specific characters can be used in specific crossbreeding systems to synchronize genetic resources with other production resources and to provide for complementarity through terminal sire breeds.
Abstract: Summary The basic objective of beef cattle crossbreeding systems is to optimize simultaneously the use of both nonadditive (heterosis) and additive (breed differences) effects of genes. Experimental results evaluating rotational crossbreeding systems indicate that high levels of heterosis are sustained in successive generations and that the relationship between loss of heterosis and loss of heterozygosity approaches linearity. Major differences among breeds have been demonstrated for most characters that contribute to production efficiency. Results based on both experimentation and computer simulation indicate that differences in additive genetic merit of breeds for specific characters can be used in specific crossbreeding systems to synchronize genetic resources with other production resources and to provide for complementarity through terminal sire breeds. Rotational crossbreeding systems have the advantage of using heterosis in all females and progeny in a self-contained commercial herd; however, fluctuation between generations in additive genetic composition relll~es use of breeds that are generally compatible. This requirement restricts the use that can be made of breed differences to synchronize germ plasm resources with other production resources and eliminates the use of complementarity other than in a combined breed-rotation, terminal-sire system. A static terminal-sire crossbreeding system provides opportunity to synchronize germ plasm resources with other production resources in about 50% of the cow herd, to use maximum (FI) heterosis in about 67% of the calves marketed and to use complementarity in
193 citations
TL;DR: Large performance differences between F1s and F2s suggest that the performance of dispersers may be affected more by fine‐scale genetic differentiation than previously assumed in this and comparable systems.
Abstract: We studied heterosis and outbreeding depression among immigrants and their descendants in a population of song sparrows on Mandarte Island, Canada. Using data spanning 19 generations, we compared survival, seasonal reproductive success, and lifetime reproductive success of immigrants, natives (birds with resident-hatched parents and grandparents), and their offspring (F1s, birds with an immigrant and a native parent, and F2s, birds with an immigrant grandparent and resident-hatched grandparent in each of their maternal and paternal lines). Lifetime reproductive success of immigrants was no worse than that of natives, but other measures of performance differed in several ways. Immigrant females laid later and showed a tendency to lay fewer clutches, but had relatively high success raising offspring per egg produced. The few immigrant males survived well but were less likely to breed than native males of the same age that were alive in the same year. Female F1s laid earlier than expected based on t...
150 citations
Cites background from "Experimental Results on Crossbreedi..."
...…from lines within species of domesticated animals because F1s from these crosses are often more fit than purebred individuals (e.g., beef cattle: Cundiff 1970; Gregory et al. 1991; dairy cattle: Turton 1981; poultry: Sheridan 1986; Omeje and Nwosu 1988; Fairfull 1990; Dunnington and Siegel…...
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TL;DR: Sufficient genetic variation exists either between or within breeds for the cattle population to be adapted to new management programs and for current methods of beef production to be significantly improved.
Abstract: In the production of high quality protein, feed grains will continue to be used to finish cattle for market as long as economics dictates. Production systems could be developed that would make ruminant animals less competitive with humans for feed grains, but the costs of instituting such programs would be prohibitive. Sufficient genetic variation exists either between or within breeds for the cattle population to be adapted to new management programs and for current methods of beef production to be significantly improved.
85 citations
TL;DR: The Brahman (American Zebu) has been evaluated in numerous crossbreeding studies throughout the Southern United States and has had lower postweaning daily gains, lower carcass grades, less backfat and higher Warner-Bratzler shear values than other contemporary straightbreds.
Abstract: The Brahman (American Zebu) has been evaluated in numerous crossbreeding studies throughout the Southern United States. Brahman females producing straightbred calves have usually been found to have a lower calving percentage, calf survival rate and weaning rate than other contemporary straightbreds, although they have been reported to be superior or competitive in some studies. Birth weights of Brahman calves have been larger than those of Angus, smaller than Charolais and comparable to those of Herefords. Brahman steers generally have had lower postweaning daily gains, lower carcass grades, less backfat and higher Warner-Bratzler shear values than other contemporary straightbreds. Heterosis estimates for reproduction have been small and variable in producing F1 calves, but larger and positive for reproductive traits of F1 cows. Birth and weaning weight heterosis estimates averaged 3.3 and 21.7 kg for F1 calves and 1.9 and 31.1 kg for calves of F1 cows. Small and variable heterosis estimates have been found for all carcass traits.
72 citations
TL;DR: It has been concluded that (1) the comparisons between genotypes should include various feeding levels, and (2) it is necessary to adjust the energy allowances according to the genotype of animals.
72 citations