Estimativa de parâmetros genéticos e análise de componentes principais em características de interesse econômico em búfalas leiteiras Murrah utilizando o cromossomo X

Abstract

The aim of the present study was to estimate the genetic parameters for productive and reproductive traits of Dairy buffaloes herds in three scenarios: the first scenario using only phenotype and pedigree data; the second one using phenotype, pedigree and and genomic information of autosomal chromosomes and the third scenario with all the previous information plus genomic information from the X chromosome. The selected traits are Milk Yield (MY), Fat Yield (FY), protein yield (PY), fat percentage (FP), protein percentage (PP), Somatic cells score (SCS), total solids (TS) for three lactations, age at first calving (AFC), calving interval between second and first lactation (IC1) and calving interval between third and second lactation (IC2). Were used in this study a database with 4.782 Murrah buffalo cows which 1.222 genotyped with the 90k Axiom® Buffalo Genotyping Array (Affymetrix/Thermo Fisher Scientific). Genetic parameters were calculated by bayesian inference using BLUPF90 family softwares. It was used an animal model with contemporary groups (defined based on herd, calving year and calving season) as fixed effects, age linear effect and quadratic effect as covariate and animal as Random effect. The estimated heritabilities (h2) ranged between 0.21 e 0.36 in first scenario; between 0.19 and 0.35 in the second scenario and between 0.18 and 0.35 in the third one for MY. For FY ranger between 0.10 and 0.11 in first scenario; 0.07 and 0.15 in second and third scenarios. For PY the heritabilities varied between 0.05 and 0.19 in first scenario; between 0.04 and 0.12 in second and third ones. From 0.09 to 0.21 in first scenario; from 0.07 to 0.22 in second and third scenario for FP. For PP varied from 0.08 to 0.26 in first scenario; from 0.08 to 0.21 in second and third scenario. For TS varied from 0.05 to 0.12 in first scenario; from 0.06 to 0.1 in second scenario and from 0.05 to 0.1 in the last one. For SCS it varied between 0.14 and 0.32 in the first one; 0.18 and 0.31 in second one and between 0.18 and 0.30 in the last one. For reproductive traits the heritabilities ranged between 0.04 and 0.07 for CI and varied between 0.33 na 0.35 for AFC in all three scenarios. Given the data presented, it is possible to conclude that the X chromosome did not significantly impact the estimates of the variance coefficients and the heritability coefficient.