| Titles |
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English :
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Genetic parameters for milk yield and some reproductive traits of Holstein cows using Reml and Gibbs sampling
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| Abstract |
A total of lactation records were obtained from 726 Holstein cows raised at a commercial farm. Variance components were estimated using two procedures: REML and Gibbs sampling with a multiple-traits repeatability animal model. The model included year-season of calving (16 groups) and parity (first three lactations) as fixed effects and additive genetic and permanent environmental as tandom effects. Records were analyzed to compare (co) variance estimates for 305 day milk yield, day open and number of services per conception obtained by both procedures.
REML estimates of heritability for the three traits were 0.090, 0.045 and 0.003, respectively. The corresponding repeatability estimates were 0.386, 0.081 and 0.030. Gibbs sampling estimates of heritability for the same traits were 0.313, 0.024 and 0.022, respectively, where, the corresponding estimates for repeatability were 0.354, 0.056 and 0.045.
REML genetic correlations between 305- day milk yield and each of days open and number of services per conception were 0.605 and 0.974, respectively. The corresponding Gibbs sampling estimates were 0.684 and 0.601. These high and positive estimates of genetic correlations indicate that the nature of the relationship between milk yield and fertility traits may cause a problem in realizing rapid improvement for both of them simultaneously.
REML phenotypic correlations between 305- day milk yield and each of days open and number of services per conception were 0.131 and 0.091, respectively. The corresponding Gibbs sampling estimates were 0.121 and 0.085. Estimates form both procedures appeared to be similar.
REML genetic and phenotypic correlations between days open and number of services per conception were 0.706 and 0.703, respectively. The corresponding Gibbs sampling estimates were similar (0.655 and 0.702).
The results indicated that heritability estimate for 305 day milk yield was much higher using Gibbs sampling. Although heritability estimate for 305 day milk yield was much higher using Gibbs sampling. Although heritbility estimates for the reproductive traits were not similar from both procedures, they were all low indicating that the direct genetic selection to improve these traits would be ineffective. Running time for the multitrait analysis using REML was almost six hours and that needed using Gibbs sampling was almost two weeks :
Abbreviation key: 305-MY = 305 day milk yield, DO = Days Open, NSPC = Number of services per conception, DF – REML = Derivative Free – REML, GS = Gibbs Sampling. BLUP = Best Linear Unbiased Prediction, ML = Maximum Likelihood.
Keywords: cattle, reml and gibbs sampling, genetic parameters, production, reproduction.
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| Publication year |
2000
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| Pages |
23-27
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| Availability location |
معهد بحوث الانتاج الحيوانى- شارع نادى الصيد - الدقى - الجيزة
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| Availability number |
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| Organization Name |
Animal Production Research Institute (APRI)
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| City |
الاسكندرية
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| serial title |
All Africa / ESAP Conference of Animal Production, Alexandria, Egypt, Nov. 6-9,2000.23-27
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| Author(s) from ARC |
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| External authors (outside ARC) |
سامى ابو بكر
جامعة القاهرة
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| Agris Categories |
Animal husbandry
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AGROVOC
TERMS |
Cattle.
Cows.
Genetic parameters.
Milk yield.
Production.
Reproductive performance.
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| Proposed Agrovoc |
reml and gibbs sampling;
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| Publication Type |
Conference/Workshop
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