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| Author(s): |
Elizangela Domenis Marino
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Pirassununga. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT) |
| Defense date: | 2021-09-10 |
| Examining board members: |
Ana Maria Centola Vidal;
Júlio César de Carvalho Balieiro;
Rodrigo Giglioti;
Anibal Eugenio Vercesi Filho
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| Advisor: | Ana Maria Centola Vidal |
| Abstract | |
This work aimed to identify possible genotypic and phenotypic effects occurring in cows with the A1 and A2 alleles of β-casein (β-CN) and to evaluate the characteristics of production, composition and somatic cell count (CCS) of milk from cows with the A1A1, A1A2 and A2A2 genotypes. For the genotypic analysis, information from 1,816 Holstein cows was used, from 2015 to 2019 and characterized as allelic (A1 and A2) and genotypic (A1A1, A1A2 and A2A2) frequencies, associated with 1,816 lactations. The different genotypes with the following phenotypic characteristics were also related: total milk production, milk production adjusted to 305 days, protein, fat, lactose, total dry extract and defatted extract and somatic cell count (CCS). With this study it was possible to conclude that according to the results obtained for a herd of high-yielding Holstein cows, there was no difference between the genotypes for a milk composition and CCS and both genotypes of reference values within the values provided by the instruction Normative No. 76. However, animals with the A1A1 genotype were shown to have a higher milk production adjusted to 305 days of lactation. In addition, the herd is in Hardy-Winberg Equilibrium so far, indicating that these animals are responsive to genetic selection of the A2 allele. (AU) | |
| FAPESP's process: | 19/11585-6 - Genotypic, phenotypic and milk composition study of cows with alleles A1 and A2 of Beta-Casein |
| Grantee: | Elizangela Domenis Marino |
| Support Opportunities: | Scholarships in Brazil - Master |