A total of more than 2,000,000 records on casein contents were collected in Lombardia (Italy) during routine milk recording of Italian Holstein and Brown Swiss dairy cows. Variance components for casein were estimated as well as all the genetic correlations of casein with production and type traits considered in selection. According to the heritabilities estimated (12.4% for Brown and 9.36% for Holstein), breeding values were calculated for bulls and compared to the breeding values for total protein. The results of two different selection scenarios were compared for each breed when including protein or casein as selection criterion. Genetic progress expected for all traits selected were compared after 10 years of selection. The genetic variability of casein allows the use of this trait as selection criterion with the estimation of breeding values and its inclusion in selection indexes. Ranking of breeding values for casein and protein are very similar in both breeds. But some differences in genetic values for casein exist for the same level of breeding value for protein. Nevertheless results in genetic gain differ between breeds depending mainly on genetic correlations with the other traits selected. The positive results in selection response estimated for several traits suggest to the Brown Swiss Association the replacement of protein selection with casein. In contrast the smaller effects estimated for the Italian Holstein suggest to wait for more casein data collected before any change in selection program.

Genetic parameters and selection for casein content in Italian Holstein and Brown Swiss / A.B. Samorè, F. Schiavini, F. Canavesi, A. Rossoni, R.M. Rizzi, A. Bagnato. - In: ITALIAN JOURNAL OF ANIMAL SCIENCE. - ISSN 1594-4077. - 8:Suppl. 2(2009), pp. 144-146. ((Intervento presentato al 18. convegno ASPA Congress tenutosi a Palermo nel 2009.

Genetic parameters and selection for casein content in Italian Holstein and Brown Swiss

A.B. Samorè
Primo
;
F. Schiavini
Secondo
;
F. Canavesi;A. Rossoni;R.M. Rizzi
Penultimo
;
A. Bagnato
Ultimo
2009

Abstract

A total of more than 2,000,000 records on casein contents were collected in Lombardia (Italy) during routine milk recording of Italian Holstein and Brown Swiss dairy cows. Variance components for casein were estimated as well as all the genetic correlations of casein with production and type traits considered in selection. According to the heritabilities estimated (12.4% for Brown and 9.36% for Holstein), breeding values were calculated for bulls and compared to the breeding values for total protein. The results of two different selection scenarios were compared for each breed when including protein or casein as selection criterion. Genetic progress expected for all traits selected were compared after 10 years of selection. The genetic variability of casein allows the use of this trait as selection criterion with the estimation of breeding values and its inclusion in selection indexes. Ranking of breeding values for casein and protein are very similar in both breeds. But some differences in genetic values for casein exist for the same level of breeding value for protein. Nevertheless results in genetic gain differ between breeds depending mainly on genetic correlations with the other traits selected. The positive results in selection response estimated for several traits suggest to the Brown Swiss Association the replacement of protein selection with casein. In contrast the smaller effects estimated for the Italian Holstein suggest to wait for more casein data collected before any change in selection program.
Casein; Dairy cows; Genetic parameters; Selection
Settore AGR/17 - Zootecnica Generale e Miglioramento Genetico
Associazione per la Scienza e le Produzioni Animali
ASPA
http://www.aspajournal.it/index.php/ijas/article/view/ijas.2009.s2.144/324
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/142134
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