Measures such as residual feed intake(RFI)have been increasingly considered to select cattle with superior feed efficiency,as it is a characteristic of feed efficiency calculated as the difference between observed int...Measures such as residual feed intake(RFI)have been increasingly considered to select cattle with superior feed efficiency,as it is a characteristic of feed efficiency calculated as the difference between observed intake and estimated intake considering metabolic weight and the weight gain.Estimated feed intake is obtained through the multiple regression equation of observed consumption on metabolic mean live weight and weight gain.The standard was shared among animals into one herd selected for low RFI(high efficiency)and compared to the one selected for high RFI(low efficiency).There was no correlated response in weight per year and in weight gain,and the effectiveness of low RFI selection in reducing feed costs was proven without affecting production.However,selection of animals with negative RFI is not done by selecting animals directly according to the size of the viscera,rather it is done indirectly,that is,when selecting the most efficient animals and normally these animals already have the smallest viscera size.The RFI is a trait that presents genetic variability,selectable to improve and has moderate heritability,between 0.30 and 0.35.The RFI is important because it reduces the direct economic impacts of reduced feed intake,as well as the effects of environmental impact on reducing methane emissions from enteric fermentation of ruminants.展开更多
文摘Measures such as residual feed intake(RFI)have been increasingly considered to select cattle with superior feed efficiency,as it is a characteristic of feed efficiency calculated as the difference between observed intake and estimated intake considering metabolic weight and the weight gain.Estimated feed intake is obtained through the multiple regression equation of observed consumption on metabolic mean live weight and weight gain.The standard was shared among animals into one herd selected for low RFI(high efficiency)and compared to the one selected for high RFI(low efficiency).There was no correlated response in weight per year and in weight gain,and the effectiveness of low RFI selection in reducing feed costs was proven without affecting production.However,selection of animals with negative RFI is not done by selecting animals directly according to the size of the viscera,rather it is done indirectly,that is,when selecting the most efficient animals and normally these animals already have the smallest viscera size.The RFI is a trait that presents genetic variability,selectable to improve and has moderate heritability,between 0.30 and 0.35.The RFI is important because it reduces the direct economic impacts of reduced feed intake,as well as the effects of environmental impact on reducing methane emissions from enteric fermentation of ruminants.
