Evaluation of Phenotypic and Genetic Trends in Weaning Weight in Angus and Hereford Populations in Virginia1

Nadarajah, Kalaivani K.; Dr, Notter; Tj, Marlowe; Al, Eller

doi:10.2527/jas1987.6451349x

Cited by 6 publications

(1 citation statement)

References 24 publications

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“…Because culling of cows on calf WW was not practiced and relationships among purchased cows were unknown, this relatively simple least squares procedure was sufficient to approximate repeatability. The resulting estimate agreed closely with the repeatability estimates of .34 and .36 reported by Nadarajah et al (1987) for WW in repeated mating involving Angus and Hereford cattle, respectively, and with the mean repeatability of WW across 16 studies of .44 reported by Petty and Cartwright (1966).…”

Section: Methodssupporting

confidence: 86%

Growth of crossbred progeny of polled Hereford sires divergently selected for yearling weight and maternal ability.

Mahrt

Notter²,

Beal³

et al. 1990

Journal of Animal Science

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Polled Hereford sires (n = 47) were divergently selected on published yearling weight (YW) and maternal (MAT) expected progeny differences (EPD) and mated to grade Angus cows to produce 457 calves in five spring calf crops. Sires selected for high and low YW differed by an average of 6.3 kg in YW EPD and those selected for high and low MAT differed by an average of 4.0 kg in MAT EPD based on 1989 EPD values. Calves by high-YW sires were heavier at birth (2.2 kg; P less than .10) and weaning (7.5 kg; P less than .01) and as yearlings (16.4 kg; P less than .01) than calves by low-YW sires and were taller at weaning (1.90 cm; P less than .01). Regressions of calf performance on corresponding 1989 EPD were 1.18 +/- .20 kg/kg for birth weight, .75 +/- .24 kg/kg for weaning weight and 1.79 +/- .42 kg/kg for YW. Expected progeny differences for individual sires were calculated from the data collected in this study and had correlations with published EPD of .53 for birth weight, .37 for weaning weight and .54 for YW. These corresponded to expected correlations based on accuracies of evaluation of .68, .61 and .58, respectively, and yielded estimates of the genetic correlation between performance in the environment of the study and the environment of the purebred herds where the published EPD were derived of .78 for birth weight, .61 for weaning weight and .93 for YW. The very large regression of YW on YW EPD (1.79 +/- .42 kg/kg) may have resulted from bias in published EPD due to culling of calves at weaning in purebred herds. Use of multiple traits analyses to account for such culling is recommended.

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Section: Methodssupporting

confidence: 86%

Growth of crossbred progeny of polled Hereford sires divergently selected for yearling weight and maternal ability.

Mahrt

Notter²,

Beal³

et al. 1990

Journal of Animal Science

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Genetic evaluation of birth and weaning weight of Gudali and two-breed synthetic Wakwa beef cattle populations under selection in Cameroon: genetic and phenotypic trends

Tawah¹,

Rege²,

Mbah³

et al. 1994

Anim. Sci.

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Breeding programmes for Wakwa and Ngaundere Gudali cattle breeds were initiated in Wakwa (Cameroon) in 1952 and 1965, respectively, to improve growth performance of the indigenous breeds. Animals were selected on 240-day weaning weight (WWT). Data analysed covered the period 1971 through 1985 and consisted of 2211 calf birth weight (BWT) and 1409 WWT records on Gudali and 1196 BWT and 763 WWT records on Wakwa. Selection responses in BWT and WWT were estimated as regressions of average sire estimated transmitting abilities (ETAs) and average dam estimated breeding values (EBVs) on year of calving. ETAs and EBVs were predicted using best linear unbiased prediction procedures. Estimated annual changes in sire ETAs for WWT were 0·67 (s.e. 0·17) and 1·69 (s.e. 1·13) kg/year for Gudali and Wakwa, respectively. Corresponding trends in dam EBVs were –0·03 (s.e. 0·03) and –0·24 (s.e. 0·19) kg/year. Estimated correlated trends in BWT among Gudali and Wakwa sires were 0·09 (s.e. 0·05) and –0·14 (s.e. 0·04) kg/year, respectively. Corresponding correlated trends in BWT associated with dam selection were essentially zero, being –0·001 (s.e. 0·001) and –0·01 (s.e. 0·01) kg/year. Environmental trends were negative for all traits except Gudali WWT. Phenotypic trends were all positive, except that of Wakwa BWT. Overall, selection on WWT yielded moderate selection reponse despite substantial infrastructural constraints in the breeding programme. Trends in sire ETAs and dam EBVs for WWT jointly accounted for estimated genetic gains of 8·60 kg in Gudali and 20·4 kg in Wakwa over the study period. Overall correlated response in BWT during the study period was significant (P < 0·001) and negative for Wakwa. It was positive but not significant for Gudali.

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Progrès génétiques pour la croissance dans une expérience de sélection portant sur deux races bovines bouchères, pure et synthétique, dans un environnement tropical

Ebangi

Erasmus

Tawah

et al. 2002

Rev. Elev. Med. Vet. Pays Trop.

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Des données recueillies entre 1968 et 1988 sur les bovins de la Station zootechnique et de recherche de Wakwa, à Ngaoundéré au Cameroun, au cours d’une expérience de sélection portant sur une race pure (Goudali) et une race synthétique (Wakwa) ont été analysées avec des procédures statistiques de modèles mixtes. L’estimation du progrès génétique a montré que les tendances moyennes annuelles génétiques directes étaient positives et significatives (p < 0,01) pour le gain de poids moyen quotidien avant sevrage, le poids à la naissance, le poids au sevrage, le poids à un an et le poids à dix-huit mois chez les deux races. Les tendances annuelles des effets maternels correspondant à ces caractères, à l’exception du gain de poids moyen quotidien avant sevrage chez les Goudali et du poids à dix-huit mois chez les Wakwa, étaient significatives (p < 0,05) mais négatives. La différence entre les réponses directes correspondantes chez les Goudali et les Wakwa n’était pas significative. En conclusion, l’amélioration génétique par sélection des caractères de croissance est possible dans un environnement tropical difficile, aussi bien chez la race synthétique que chez la race locale. L’antagonisme génétique entre les effets génétiques directs et maternels est troublant et nécessite des études plus approfondies.

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Evaluation of Phenotypic and Genetic Trends in Weaning Weight in Angus and Hereford Populations in Virginia1

Cited by 6 publications

References 24 publications

Growth of crossbred progeny of polled Hereford sires divergently selected for yearling weight and maternal ability.

Growth of crossbred progeny of polled Hereford sires divergently selected for yearling weight and maternal ability.

Genetic evaluation of birth and weaning weight of Gudali and two-breed synthetic Wakwa beef cattle populations under selection in Cameroon: genetic and phenotypic trends

Progrès génétiques pour la croissance dans une expérience de sélection portant sur deux races bovines bouchères, pure et synthétique, dans un environnement tropical

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