Genetic analyses of milk and milk fat yields measured at various lactations of Iranian Holstein cows using appropriate models

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PIRASTEH A.; ASADI FOZI M.; ESMAILIZADEH KASHKOUEIYEH A.

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Journal: Journal of Animal Research Year:2019 | Volume:32 | Issue:3 Page(s): 259-271

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Title

Genetic analyses of milk and milk fat yields measured at various lactations of Iranian Holstein cows using appropriate models

Author(s)

PIRASTEH A. | ASADI FOZI M. | ESMAILIZADEH KASHKOUEIYEH A. | Issue Writer Certificate

Keywords

Milk yieldQ1

Milk fatQ1

Holstein cowQ1

Genetic analysisQ1

Multivariate modelQ1

Abstract

In this study, appropriate genetic co(variance) structure across ages of milk and fat yields in five lactation periods of Iranian Holstein cows was determined using 53138 records originated from 1510 sires and 4835 dams. These data were collected by Iranian Animal Breeding Center from 436 dairy herds. These cattle were born in two years: 2005 and 2006 in various provinces. The milk production records in the first to fifth lactation were 50578, 35970, 24337, 15445 and 8012 kg, respectively. While the fat milk records were 19463, 17935, 14451, 10729 and 6322 kg, respectively. To determine the best model for Genetic analysis of the aforementioned traits, unstructured multivariate, prestructured multivariate and repeatability models were used. To study the importance of fixed and random effects on milk and Milk fat yields, univariate model was applied. In this model, the fixed effects of birth year, birth month, calving year, number of milking, state and herd-calving year, calving season had significant effects on the milk and Milk fat yields. The animal effect was fitted as the only important random effect. The best Multivariate model was selected based on Bayesian Information Criterion (BIC), accordingly a tree variate model was the best model for genetic analyses of both milk and Milk fat yields compared to other models including an unstructured Multivariate model. Based on this model, heritability for milk production in the five lactations was respectively, 0. 21, 0. 15, 0. 12, 0. 11 and 0. 11 and for Milk fat were evaluated as 0. 15, 0. 12, 0. 11, 0. 09 and 0. 09, respectively. Based on the results derived from the best models, the milk and Milk fat yields are genetically partitioned into 3 different groups including 1 sth nd lactation, 2 lactation and the later consisting of rd th th 3, 4 and 5 lactations. Accordingly, accuracy of genetic evaluation of the Iranian Holstein cows can be improved when the milk and Milk fat yields measured at second and third lactations as well as the first lactation. Unity genetic correlation was estimated among the milk and Milk fat yields measured at 3 rd th th, 4 and 5 lactations. Therefore, the selection accuracy not be increased using the later records after 3 rd lactations including th th 4 and 5 lactations.

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APA: Copy

PIRASTEH, A., ASADI FOZI, M., & ESMAILIZADEH KASHKOUEIYEH, A.. (2019). Genetic analyses of milk and milk fat yields measured at various lactations of Iranian Holstein cows using appropriate models. JOURNAL OF ANIMAL RESEARCH (IRANIAN JOURNAL OF BIOLOGY), 32(3 ), 259-271. SID. https://sid.ir/paper/370994/en

Vancouver: Copy

PIRASTEH A., ASADI FOZI M., ESMAILIZADEH KASHKOUEIYEH A.. Genetic analyses of milk and milk fat yields measured at various lactations of Iranian Holstein cows using appropriate models. JOURNAL OF ANIMAL RESEARCH (IRANIAN JOURNAL OF BIOLOGY)[Internet]. 2019;32(3 ):259-271. Available from: https://sid.ir/paper/370994/en

IEEE: Copy

A. PIRASTEH, M. ASADI FOZI, and A. ESMAILIZADEH KASHKOUEIYEH, “Genetic analyses of milk and milk fat yields measured at various lactations of Iranian Holstein cows using appropriate models,” JOURNAL OF ANIMAL RESEARCH (IRANIAN JOURNAL OF BIOLOGY), vol. 32, no. 3 , pp. 259–271, 2019, [Online]. Available: https://sid.ir/paper/370994/en

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