Prediction of body chemical composition of Morada Nova ram lambs using the composition of ribs section between 9th and 11th

The determination of the chemical composition of the body and carcass is important in nutritional and growth regulation studies. The purpose of this study was to develop equations to predict the chemical composition of the body and carcass using the chemical composition of a section from 9-11th rib in Morada Nova lambs. Forty-eight Morada Nova lambs with an initial weight of 12.05 +/- 1.81 kg, were used. Eight animals were slaughtered at the beginning of the trial as a reference group in order to estimate the initial empty body weight and body composition. The remaining animals were assigned to a randomized block design with eight replications per block and five diets with increasing metabolizable energy contents (0.96, 1.28, 1.72, 2.18, and 2.62 Mcal/kg of dry matter). Animals were slaughtered when the mean of body weight of the group reached 25 kg. Body chemical composition was determined by evaluating the composition of the right half of the carcass, as well as, by using a sample between the 9-11th ribs (the HH section) from the left half of the carcass. According to Pearson's correlation coefficient, the use of the HH section precisely predicted the percentages of protein (r = 0.89), ether extract (r = 0.81) and minerals (r = 0.83). Equations were developed to estimate the percentage of protein, ether extract, ash in the carcass from the following components in the HH section: %CP in the carcass = -21.05 + 3.052*%CP in the HH section (r(2) = 0.83); %EE in the carcass = -6.443+2.879*%EE in the HH section (r(2) = 0.76); % Ash = 4.52-0.362*%Ash in the HH section (r(2) = 0.15); % Water = 7.55+0.878*% Water in HH section (r(2) = 0.85). The cut from the 9-11th ribs satisfactorily predicted the protein and ether extract contents in the empty body, with values of r = 0.84 and 0.78, respectively. The crude protein and ether extract contents of the empty body can be satisfactorily estimated from chemical composition of the HH section; however, more information must be generated to obtain more reliably applicable equations.