| Autor: |
Perez BC; 1Department of Animal Sciences,College of Animals Science and Food Engineering,University of São Paulo (FZEA/USP),Pirassununga,13630-000 São Paulo,Brazil., Silva FF; 2Department of Animal Science,Federal University of Viçosa,Viçosa,36570-900 Minas Gerais,Brazil., Ventura RV; 3Beef Improvement Opportunities (BIO),Elora,N1K 1E5 Ontario,Canada., Bruneli FAT; 5National Center of Research on Dairy Cattle,Brazilian Agricultural Research Corporation(CNPGL/EMBRAPA),Juiz de Fora,36038-330 Minas Gerais,Brazil., Balieiro JCC; 6College of Veterinary Medicine and Animal Science,University of São Paulo (FMVZ/USP),Pirassununga,13630-000 São Paulo,Brazil., Peixoto MGDC; 5National Center of Research on Dairy Cattle,Brazilian Agricultural Research Corporation(CNPGL/EMBRAPA),Juiz de Fora,36038-330 Minas Gerais,Brazil. |
| Abstrakt: |
Four models for in vitro embryo production traits in Guzerá cattle were compared: Gaussian (untransformed variable - LIN and transformed in logarithmic scale - LOG), Poisson (POI) and zero-inflated Poisson (ZIP). Data consisted of 5716 ovum pick-up and in vitro fertilization records performed in 1205 cows from distinct regions of Brazil. Analyzed count traits were the number of viable oocytes (NOV), number of grade I oocytes (NGI), number of degenerated oocytes (NDG), number of cleaved embryos (NCLV) and number of viable produced embryos (NEMB). Heritability varied from 0.17 (LIN) to 0.25 (POI) for NOV; 0.08 (LOG) to 0.18 (ZIP) for NGI; 0.12 (LIN) to 0.20 (POI) for NDG; 0.13 (LIN) to 0.19 (POI) for NCLV; 0.10 (LIN) to 0.20 (POI) for NEMB depending on the considered model. The estimated repeatability varied from 0.53 (LOG) to 0.63 (POI) for NOV; 0.22 (LOG) to 0.39 (ZIP) for NGI; 0.29 (LIN) to 0.42 (ZIP) for NDG; 0.42 (LIN) to 0.59 (POI) for NCLV; 0.36 (LIN) to 0.51 (POI) for NEMB. The goodness of fit, measured by deviance information criterion and mean squared residuals, suggested superiority of POI and ZIP over Gaussian models. Estimated breeding values (EBV) obtained by different models were highly correlated, varying from 0.92 for NOV (between LIN-POI) and 0.99 for NGI (between POI-ZIP). The number of coincident animals on the 10% top EBV showed lower similarities. We recommend POI and ZIP models as the most adequate for genetic analysis of in vitro embryo production traits in Guzerá cattle. |
