| Titles |
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English :
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Estimation of phenotypic and genetic parameters for test-day milk yield and somatic cell count in the first three lactations of Egyptian buffalo using random regression
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| Abstract |
Both fixed and random regressions were used to model test day records that are measured over the trajectory from days in milk (DIM) = 5 to 300-d of the first three lactations for Egyptian buffalo. The (co)variance components were estimated with a single trait animal model with REML algorithm for each of daily milk yield (DMY) and log10 SCC (LSCC) for a total of 3189 records. Records were taken from four buffalo experimental research stations belonging to the Animal Production Research Institute, Egypt between 1999 and 2004. The present study aimed at studying the pattern of inheritance, permanent environmental variance, and residual variance for DMY and LSCC in the first three parities of Egyptian buffalo.
Heritability estimates within each parity for DMY and LSCC had wide ranges in all parities. Average heritability estimates for LSCC was 0.15, 0.07 and 0.09 for the three parities, respectively. Estimates in general tended to increase toward edges of the trajectory. Permanent environmental variances for DMY were relatively low at early lactation and tended to increase toward the end of the trajectory. Residual variances were low at both edges of the 3rd parity contradicting the first and second parities. All variances (genetic, permanent environmental and residual) were very high for LSCC in the first parity while they were low in second and third parities. This result may suggest that LSCC in first parity is not genetically the same as in the rest of parities. correlations among DIM for each of DMY and LSCC were generally high between adjacent records and tended to decrease when records are further apart. Permanent environmental and phenotypic correlations had the same trend.
Keywords: genetic parameters, test day, milk yield, somatic cell count, Egyptian buffalo, random regression
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| Publication year |
2004
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| Pages |
15-31
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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 |
المنصورة
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| serial title |
12th Scientific Conference, Egyptian Society of Animal Production. Mansoura University, Egypt, November 29, December (3 )2004. Egyptian Journal Animal Production 41 (Suppl. Issue): 15-31.
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| Author(s) from ARC |
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| External authors (outside ARC) |
على عطية نجم
جامعة القاهرة
محمد عبد العزيز محمد ابراهيم
جامعة القاهرة
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| Agris Categories |
Animal genetics and breeding
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AGROVOC
TERMS |
Genetic parameters.
Milk yield.
Phenotypes.
Somatic cell count.
Statistical methods.
Water buffaloes.
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| Publication Type |
Conference/Workshop
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