Studies on Sheep Production Records

Eikje, Einar D.

doi:10.1080/00015127409434200

Cited by 9 publications

(7 citation statements)

References 2 publications

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“…Results from the late 1970s and 1980s showed considerably lower values. However, our larger annual genetic change for weaning weight, than for carcass weight, contrasts with the results of Eikje (1975a), who found similar values for genetic change of both traits, actually indicating an increase of the dressing percentage. One explanation for the results stated was a high heritability for carcass weight, and also the pattern of genetic correlation found between dressing percentage and carcass and weaning weight (0.62 and 20.18), respectively (Gjedrem, 1971).…”

Section: Resultscontrasting

confidence: 55%

“…Correspondingly, an aggregate economic phenotype was calculated by multiplying the phenotypes of the same traits (Table 3) by the economic values. In per cent of the aggregate phenotype, the calculated genetic gain in the aggregate genotype turned out to be 1.25%, equal to that of Eikje (1975a). These results were larger than the values of 1.02% and 0.52% from the late 1970s and early 1980s, obtained by Steine (1982a and1986).…”

Section: Resultscontrasting

confidence: 50%

“…in the index produced for selection of 1.5-year-old test rams, including carcass weight, carcass quality and fleece weight of lambs. For this index, Eikje (1975a) found the gain to be 1.25% per year (1.25 index units change for an average index of 100). To compare our results with previous ones, for the aforementioned index, genetic gain in the aggregate genotype was calculated as the sum of the products between the genetic gain in carcass weight, carcass grade, fat grade and fleece weight of lambs (Table 1) and their economic weights (Appendix).…”

Section: Resultsmentioning

confidence: 99%

“…Key elements were selection of ram lambs on pedigree and own performance, selection of rams on progeny test results in ram circles and selection of ewes according to a selection index (Gjedrem, 1969;Eikje, 1977;Steine, 1982a;Vangen et al, 2003). Early calculations clearly indicated a positive genetic change from selection (Eikje, 1975a;Eikje and Steine, 1976), although the gain for some traits was not significantly different from zero. These studies also suggested a genetic loss for fleece weight.…”

Section: Introductionmentioning

confidence: 99%

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The Norwegian sheep breeding scheme: description, genetic and phenotypic change

Eikje

Ådnøy

Klemetsdal

2008

Animal

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The developments in Norwegian sheep breeding since the early 1990s are reviewed. For the largest breeding population, the Norwegian White Sheep, results are presented for both genetic and phenotypic changes. Of the nine traits that make up the aggregate genotype, the largest gain per year, in per cent of the corresponding phenotypic average, was found for carcass grade (1.66%) and carcass weight (0.99%), number of lambs born at 1, 2 and 3 years of age (0.32% to 0.60%) and the maternal effect on weaning weight (0.26%). For fat grade, a genetic deterioration was estimated. This may be due to the too small weighting of this trait in the aggregate genotype and the true genetic parameters being somewhat different from the estimates in the prediction of breeding values. For lamb as well as ewe fleece weight, genetic change was close to zerointerpreted as mainly a correlated response to other traits in the aggregate genotype. Data for the two traits of fleece weight were, respectively, selected and few. Thus, phenotypic change was calculated for all traits except for fleece weight, and in addition for number of lambs at weaning, being indirectly selected for through number of lambs born. For all traits, with the exception of fat grade, advantageous phenotypic change was estimated. For weaning and carcass weight, the phenotypic change was less than the genetic change, while the opposite was observed for carcass and fat grade and number of lambs born. The latter traits can be more easily controlled by environmental actions, and the results thus exemplify the interdependency between environmental and genetic change.

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Section: Resultscontrasting

confidence: 55%

Section: Resultscontrasting

confidence: 50%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Norwegian sheep breeding scheme: description, genetic and phenotypic change

Eikje

Ådnøy

Klemetsdal

2008

Animal

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“…With the exception of a study in Norway (Eikje 1974), earlier studies on breed evaluation (Sidwell et al 1964l ' Sidwell and Miller 1971;Dickerson et al 19721,Yesely and Peters 197 2, 191 9 ; Shrestha et al l9'7 4) were based on data from institutional flocks maintained for selection and crossbreeding studies. In the present study, daily gain and body weights of lambs from 12 different breeds of sheep (Shrestha et al 1982a;Anonymous 1983). Statistical Analysis Least squares procedures (Harvey 1975 Olson et al 1976).…”

mentioning

confidence: 99%