Measuring Genetic Change in a Dairy Herd Using a Control Population

Legates, J.E.; Myers, R.M.

doi:10.3168/jds.s0022-0302(88)79649-6

Cited by 18 publications

(8 citation statements)

References 12 publications

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“…Direct and correlated responses from designed selection experiments for milk yield have been reported in previous studies (Legates and Myers, 1972;Hansen et al, 1979;Meland et al, 1982;Wautlet et al, 1990;Boettcher et al, 1993). Legates and Myers, (1972) reported an average response of 121 kg of milk per year.…”

Section: Introductionmentioning

confidence: 58%

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Genetic Parameters and Responses of Linear Type, Yield Traits, and Somatic Cell Scores to Divergent Selection for Predicted Transmitting Ability for Type in Holsteins

Degroot¹,

Keown²,

Vleck³

et al. 2002

Journal of Dairy Science

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The objective was to examine the direct and correlated responses of linear type, yield traits, and somatic cell scores (SCS) to divergent selection for predicted transmitting ability for type (PTAT) in Holsteins, while maintaining selection for yield traits across lines. For four generations, one-half of the University of Nebraska research Holstein herd was bred to Holstein sires with PTAT > 1.50 and the other half to sires with PTAT < 1.25, with nearly equal predicted transmitting abilities for yield traits for both groups. Estimates of genetic and residual correlations and heritabilities were obtained from REML estimates of (co)variance components. Model for type traits included fixed effect of date cows were classified, effects of age in days at freshening, and stage of lactation at classification. Year-season when cows freshened was fixed effect in model for yield and SCS. Animal genetic and residual effects were random. Final score, milk, fat, and protein yields, and SCS had heritability estimates of 0.38, 0.13, 0.22, 0.09, and 0.38, respectively. Heritability estimates for type traits ranged from 0.04 to 0.52. Estimates of genetic correlations of final score with SCS and milk, fat, and protein yields were −0.64, 0.01, −0.18, and 0.06, respectively. Estimates of genetic correlations among linear type traits ranged from −0.77 to 1.00. Means of estimated breeding values for final score, stature, strength, body depth, fore udder attachment, rear udder height and width, udder cleft, udder depth, and front teat placement were significantly different between lines in the third generation. Milk, fat, and protein yields were not significantly different between lines in third generation, whereas SCS was significantly different. Estimate of genetic correlation between final score and SCS sug-

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Section: Introductionmentioning

confidence: 58%

“…Legates and Myers, (1972) reported an average response of 121 kg of milk per year. The experimental herd at the University of Minnesota had a genetic trend of 126 kg per year from 1967 to 1988 .…”

Section: Introductionmentioning

confidence: 99%

Genetic Parameters and Responses of Linear Type, Yield Traits, and Somatic Cell Scores to Divergent Selection for Predicted Transmitting Ability for Type in Holsteins

Degroot¹,

Keown²,

Vleck³

et al. 2002

Journal of Dairy Science

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“…EGT was estimated using the method procedures Legates and Myers (1988). Environmental using (SAS, 2003), The resultant output was then plotted in graphs to represent the general trend of the behavior of the fixed effect under consideration (parity, year and season).…”

Section: Epigenetic Trend (Egt)mentioning

confidence: 99%

Estimation of Genetic and Phenotypic Parameters for Growth Traits of Friesian Cattle Raised in Egypt.

Sanad¹,

Gharib²

2017

Journal of Animal and Poultry Production

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Growth traits (GT) of 1691 Friesian calves by 74 sires and 789 dams over a 20 years (1997 to 2016) in Alkarda Farm, Egypt. Traits studied were weight at birth weight (BW), weaning weight (WW) and daily gain (DG). Records were analyzed Multiple Trait Likelihood (MTDFREML) to estimate covariance components and Heritability(h 2), genetic correlations(r G) , maternal correlations (r m) and phenotypic correlations(r P), breeding values(BV), and Epigenetic trend (EGT)for growth traits (GT) of Friesian cattle raised in Egypt. Actual mean for BW,WW and DG were 28.6kg, 92.6kg and 0.60 gm , respectively. Direct heritability (h 2 a) estimates for BW, WW and DG were 0.32±0.06, 0.22±0.06 and 0.34±0.85, respectively; on the same time low maternal heritability (h 2 m) were 0.12±0.35, 0.08±0.49 and 0.18±0.71, respectively. The permanent environment (P 2) was 0.021±0.70, 0.030±0.77 and 0.058±0.72 for BW, WW and DG, respectively. Phenotypic correlation (r P) were 0.99m while, direct genetic correlation (r g) are ranged from 0.56 to 0.96.While, maternal correlations (r m) ranged from were 0.48, to 0.93. Rang of breeding value (BV) estimated of calves for BW, WW and DG were 51.5kg, 10.1kg and 31.2 kg , the BV of sire for the same traits 17.7 kg, 101.0kg and 12.0g. While the range of dams BV were 11.4kg, 17.8kg and 17.7gm respectively. The results showed that it is better to choose on the basis of the BV of calves to obtain highly genetic improvement. Generally the direction was (EGT) positive in the autumn and summer 'while it was negative in the winter and spring of the studied traits. In addition, the estimated genetic trends of Epigenetics that the genetic performance of cows is affected by the exist environmental conditions, as the influence of the season, parity and year, which has shown an impact at some levels, so, sufficient care is necessary help them to rapid their full genetic possibility by improving environmental conditions Inappropriate. This results in animals showing their full genetic potential for GT, thus increasing the efficiency of selection. We conclude from this study: Improve the performance of the animal under study by estimating the environmental and genetic factors and knowing their impact on growth performance, which will allow them to set standards for assessing the performance of the animals. The traits under study are high to medium in the values of genetic equivalence. The genetic correlations between the characteristics of the study are positive and high. The direct genetic and permanent effects are more effective in the selection process. The results show that all traits of growth have a clear potential for improved yield through direct genetic selection and more attention to environmental conditions through good care and selection based on breeding values. This results in animals showing their full genetic potential for growth traits, thus increasing the efficiency of selection.

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“…EP was estimated using the method reported by Legates and Myers (1988). After regressing the (BLUP) values of the engaged animals across the different classes of the insinuated environmental situations using (SAS, 2003), The resultant output was then plotted in graphs to represent the general trend of the behavior of a specific trait under changeable classes of the fixed effect under consideration (year, season and parity).…”

Section: Epigenetic Trend (Ep)mentioning

confidence: 99%

Epigenetics TREND for some Productive and Reproductive Traits of Friesian Cattle Raised in Egypt

Sanad¹,

Gharib²

2017

Journal of Animal and Poultry Production

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The objectives of this study were to estimate the genetic parameters and Epigenetics TREND (EP) of milk traits of herd of Friesian in Egypt. The studied traits were 305 day milk yield (305d-MY, kg),total milk yield (TMY, kg), Lactation period (LP, day), days open (DO) and number of services per conception (NSC, services).The data included 1794 records of 704 cows daughters of 86 bulls and 439 damduring the years 2007to 2016 were collected from Alkarda farm (Government farm) located in Kafr El-Sheikh, Egypt. Single-Trait animal model was used to estimate genetic parameter; overall means of 305-dayMY, TMY, LP, DO and NCS were 2935Kg, 3320 Kg , 310 day, 151 day and 1.7 services, respectively, Additive heritability (h a) estimated for 305d-MY, TMY, LP DO and NSC were 0.34, 0.31, 0.29, 0.06 and 0.26,respectively. While maternal heritability (h m) were 0.03, 0.07, 0.05, 0.01 and 0.002, respectively , The environmental impact of the permanent lower corresponding values were 0.0031, 0.0027, 0.0037, 0.0062 and 0.0038, respectively.Indicating that the effect of animals' genetic performance is affected by the surrounding environmental conditions where full care through the mother leads to improvement of the studied traits.The genetic and phenotypic correlations of most of the studied traits were highly significant (p <0.001) and ranged from-0.22 to 0.46for geneticcorrelationbetween traits whilephenotypic correlation ranged from-0.11 to 0.65.Genetic trends were positive for all studied traits except for days open and NSC. Range of breeding value (BV)for all studied traits of cows (

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Measuring Genetic Change in a Dairy Herd Using a Control Population

Cited by 18 publications

References 12 publications

Genetic Parameters and Responses of Linear Type, Yield Traits, and Somatic Cell Scores to Divergent Selection for Predicted Transmitting Ability for Type in Holsteins

Genetic Parameters and Responses of Linear Type, Yield Traits, and Somatic Cell Scores to Divergent Selection for Predicted Transmitting Ability for Type in Holsteins

Estimation of Genetic and Phenotypic Parameters for Growth Traits of Friesian Cattle Raised in Egypt.

Epigenetics TREND for some Productive and Reproductive Traits of Friesian Cattle Raised in Egypt

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