No abstract

The aim was to estimate the genetic correlations between residual feed intake (RFI) and dry matter intake (DMI) with carcass finish (CF), rib eye area (REA), and marbling (MAR) of Nellore cattle. Data from 7,808 animals were considered. In addition, data from 2,261 females included in the complete database were also considered. Estimates of variance and covariance components, as well as heritabilities and genetic correlations were obtained by means of two-character analysis under animal model. Heritability estimates were found to be moderate for the RFI (0.22) and DMI (0.29) traits. It was observed that genetic correlation was close to zero for all traits, except between RFI and REA (-0.11). However, considering the female population, there was an increase in the estimated genetic correlation between RFI and DMI, although still a favorable genetic association of low magnitude (-0.30). There was also an increase in the genetic association of REA with RFI (-0.21). It can be concluded that the direct selection for RFI and DMI will not influence the CF, MAR, or REA of Nellore cattle. However, this selection may generate some favorable responses in MAR and REA in Nellore females.

4Embrapa Pecuária Sudeste ˗ São Carlos, SP RESUMO Objetivou-se estimar a associação fenotípica entre a eficiência alimentar e o ganho em acabamento de carcaça de touros jovens da raça Nelore. Utilizaram-se informações de 98 touros jovens da raça Nelore, participantes de duas provas de eficiência alimentar que empregaram o sistema de cochos eletrônicos Growsafe ® , as quais foram realizadas nos anos de 2015 e 2016, na fazenda Capim Branco, da Universidade Federal de Uberlândia. As provas de eficiência alimentar tiveram duração de 91 dias, sendo 21 dias de adaptação e 70 dias de avaliação. Os animais apresentavam idade média ao início e ao término do confinamento de 19,98 e 22,16 meses e peso inicial e final médio de 428,17 e 542,27kg, respectivamente. Verificou-se que os animais mais eficientes depositaram menos gordura, e os animais menos eficientes depositaram mais gordura durante o período de avaliação em confinamento. Observouse que há uma associação fenotípica de baixa magnitude (0,29) entre o consumo alimentar residual (CAR) e o ganho em acabamento de carcaça (GACAB). Assim, pode-se inferir que, ao serem selecionados menores valores de CAR, haverá alguma interferência negativa em GACAB. Concluiu-se que animais mais eficientes (CAR negativo) podem apresentar menor deposição de gordura subcutânea, influenciando na qualidade de carcaça de bovinos da raça Nelore. Palavras-chave: consumo alimentar residual, gordura subcutânea, bovinos de corte ABSTRACTThis study aimed to estimate the phenotypic association between feed efficiency and gain in carcass finishing of young Nelore bulls. Information from 98 young Nelore bulls participating in two feed efficiency tests using the Growsafe® electronic trough system, carried out in the years 2015 and 2016, at the Capim Branco farm of the Universidade Federal de Uberlândia was used .The feed efficiency tests lasted for 91 days, with 21 days of adaptation and 70 days of evaluation. The animals had a mean age at the beginning and end of the confinement of 19.98 and 22.16 months, and mean weight initial and end of 428.17 and 542.27kg, respectively. It was verified that most efficient animals deposited less fat, and the efficient animals deposited more fat during the evaluation period at the confinement. It was observed that there is a low magnitude phenotypic association (0.29) between the residual feed intake (RFI) and the gain in carcass finishing (GACAB). Thus, it can be inferred that by selecting lower values of residual feed intake there will be some negative interference in GACAB. It was concluded that the most efficient animals (negative RFI) may present lower deposition of subcutaneous fat, influencing the carcass quality of Nelore cattle.

Objetivou-se estimar a associação fenotípica entre a eficiência alimentar e o ganho em acabamento de carcaça de touros jovens da raça Nelore. Utilizaram-se informações de 98 touros jovens da raça Nelore, participantes de duas provas de eficiência alimentar que empregaram o sistema de cochos eletrônicos Growsafe ® , as quais foram realizadas nos anos de 2015 e 2016, na fazenda Capim Branco, da Universidade Federal de Uberlândia. As provas de eficiência alimentar tiveram duração de 91 dias, sendo 21 dias de adaptação e 70 dias de avaliação. Os animais apresentavam idade média ao início e ao término do confinamento de 19,98 e 22,16 meses e peso inicial e final médio de 428,17 e 542,27kg, respectivamente. Verificou-se que os animais mais eficientes depositaram menos gordura, e os animais menos eficientes depositaram mais gordura durante o período de avaliação em confinamento. Observouse que há uma associação fenotípica de baixa magnitude (0,29) entre o consumo alimentar residual (CAR) e o ganho em acabamento de carcaça (GACAB). Assim, pode-se inferir que, ao serem selecionados menores valores de CAR, haverá alguma interferência negativa em GACAB. Concluiu-se que animais mais eficientes (CAR negativo) podem apresentar menor deposição de gordura subcutânea, influenciando na qualidade de carcaça de bovinos da raça Nelore.

The purpose of this study was to estimate the phenotypic associations between residual food intake (RFI) and carcass traits, evaluated by ultrasonography, of young Nellore bulls. Information about 53 young Nelore bulls, pure origin (PO), participants in the Individual Performance Test of Nelore Bulls, carried out at the Capim Branco experimental farm of the Federal University of Uberlândia (UFU) were used for this purpose. It was evaluated the characteristics of residual feed intake (RFI), rib eye area (REA), marbling (MAR) and fat thickness (FT). In order to estimate the Spearman and Pearson correlation coefficients, the SAS program was used. Regarding the influence of the RFI classes (low RFI, medium RFI and high RFI) on carcass traits, an out analysis of variance was carried out using the least squares method. It was verified that there was no phenotypic association between RFI and the characteristics of REA and MAR, but the relation between FT and the phenotypic association revealed a medium magnitude. However, when evaluating the RFI classes, it was observed that there were no significant differences of the RFI classes with the carcass traits (REA, FT and MAR). It is recommended that new studies are carried out to verify if the selection for RFI does not result in damages to the finishing of carcass in Nelore cattle.