GENOMIC EVALUATION OF BUFFALO LACTATION CURVES USING BAYESIAN MODELS

• Grant number: 17/23818-0
• Support type: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): May 01, 2018
• Effective date (End): April 30, 2021
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal researcher: Humberto Tonhati
• Grantee: Sirlene Fernandes Lazaro
• Home Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil
• Associated scholarship(s): 19/22136-8 - Bayesian analysis of buffalo lactation curves combining pedigree and genomic information., BE.EP.PD

Abstract

The lactation curves can be modeled by different mathematical functions (Wood, Brody, Wilmink), which present a reduced number of parameters with biological interpretations, such as the initial yield (parameter a), the ascending phase of the curve (parameter b) and the descending phase of the curve (parameter c). Thus, desirable changes in the shape of the curves can be obtained by considering the estimates of these parameters as phenotypic observations in statistical models of genetic evaluation. Currently, given the importance of genomic information for Animal Breeding, the use of these phenotypes can be expanded to more sophisticated models, such as the Genome Wide Association Study (GWAS). Therefore, this objective project to estimate lactation curves of buffaloes for the identification of earlier and more efficient animals for selection purposes; identify and select the best animals via genomic genetic values for the parameters of the lactation curves; comparing nonlinear models for genomic evaluation of lactation curves; in addition to identifying chromosomal regions and candidate genes related to the parameters of the lactation curves by GWAS. The data come from approximately 12 farms participating in the dairy control program of the Department of Animal Science of the Universidade Estadual Paulista, Campus Jaboticabal, São Paulo, located in the states of Ceará, Rio Grande do Norte and São Paulo, approximately 3,943 animals born between 1971 and 2014 will be used. In addition, 706 animals were genotyped using a panel of 90K Axiom® Buffalo Genotyping (Affymetrix). The phenotypic observations of five characteristics will be considered, being: milk production on the day of control, accumulated milk production, fat percentage, protein percentage and somatic cell count. The Bayesian hierarchical model will be applied first, to analyze the individual lactation curves based on the nonlinear regression models, after the parameters of the nonlinear models will be modeled by a linear multitrait model. The models will be compared through their predictive ability through cross validation analysis. Once the genomic values of each animal are obtained for the model parameter estimates and the best lactation model chosen, it will be possible to obtain the "genomic lactation curves" for each animal.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

LAZARO, SIRLENE F.; TONHATI, HUMBERTO; OLIVEIRA, HINAYAH R.; SILVA, ALESSANDRA A.; NASCIMENTO, V, ANDRE; SANTOS, DANIEL J. A.; STEFANI, GABRIELA; BRITO, LUIZ F. Genomic studies of milk-related traits in water buffalo (Bubalus bubalis) based on single-step genomic best linear unbiased prediction and random regression models. JOURNAL OF DAIRY SCIENCE, v. 104, n. 5, p. 5768-5793, MAY 2021. Web of Science Citations: 0.