Evaluation of equations to predict body composition in Nellore bulls

Abstract

a b s t r a c tThe equations developed by Hankins and Howe (1946, HH), Marcondes et al. (2010, M10), Marcondes et al. (in press, M11) and Valadares Filho et al. (2006, V6) were evaluated to predict the body composition from the 9-10-11th rib cut in Nellore bulls. The evaluated equations estimated the physical and the carcass chemical composition, the empty body chemical composition and the noncarcass chemical composition. Thirty-seven Nellore bulls (1471 months old initially) with shrunk body weight of 259724.9 kg were used in this experiment. The bulls were randomly divided into three groups: five bulls to the reference group, four bulls were fed at maintenance level and twenty-eight bulls were fed ad libitum. The bulls fed ad libitum were separated into four groups, one of which was slaughtered every 42 days. The diet was composed of corn silage and concentrate (55:45). After slaughter, the 9-10-11th rib cut was dissected into muscle, fat and bone fractions. The remaining carcass was similarly dissected. The others parameters that were evaluated as partial predictors included the empty body weight, the dressing percentage, the visceral fat percentage, the organ and viscera percentage and the composition of the noncarcass components. The values estimated with prediction equations were compared to the observed values. The equations obtained by M11 predicted correctly the carcass physical composition. However, the muscle and fat tissues were under-and overestimated, respectively, by HH. Some constituents of the noncarcass components can be predicted from equations developed by M10. The equations obtained by M10 predicted correctly the carcass and empty body chemical composition. The carcass water was underestimated by HH. The equations by V6 did not predict the carcass or empty body chemical composition. The carcass physical and chemical composition and empty body chemical composition can be predicted from the composition of 9-10-11th rib cut by equations obtained by Marcondes et al. (

The chemical composition of carcasses can be predicted from proxy traits in finishing male beef cattle: A meta-analysis

“…A preliminary analysis had indicated that when the carcass fat and carcass protein are expressed as concentrations (Al-Jammas, Vernet, Agabriel, and Ortigues-Marty, 2014), the residuals of the models were significantly correlated with carcass weight (results not shown). A mass unit had also been recommended by Costa et al (2013) to compare data from different breeds, ages and weights at slaughter and by Charles and Johnson (1976) to account for the large between-breed differences in carcass composition at a similar carcass weight. As a result, HCW was systematically included in the models as an independent variable.…”

“…Relationships were also derived between reference measurements and combinations of proxy traits of individual animal data (O'Mara et al, 1998). Those relationships were established under well-controlled but limited conditions, such as a given diet, breed (Costa, Valadares, Detmann, Marcondes, and Rotta, 2013) or a given sex ; consequently, they are not applicable to other conditions. Therefore, in isolation, these studies cannot test whether the relationships are robust across breeds (e.g., British vs Continental) and whether they are independent of the progress in genetic improvement.…”

Can the body composition of crossbred dairy cattle be predicted by equations for beef cattle?

“…Here, we used the equations developed for calves, whose fat deposition occurs later in heifers and in bulls. Because for this difference in the deposition of tissues between the genders, some studies have reported that these equations overestimate the amount of fat [ 4 , 9 ] and undervalue the amount of muscle [ 4 ].…”

“…The data used to test the equations are shown in Table 3 and were evaluated in their absolute weight (kg), according to the recommendations of Costa e Silva et al [ 9 ].…”

“…Work by Marcondes et al [ 4 ], Paulino et al [ 5 ], and Silva et al [ 6 ] has shown that the equations of Hankins and Howe [ 1 ] were not fully applicable for zebu, and suggested new equations and approaches [ 7 , 8 ]. These new equations were developed using data from zebu and crossbred cattle and validated for Nellore cattle [ 9 ], which differ from Holstein×Gir crossbred cattle.…”