Evaluation of Antipyrine, N-Acetyl-4-Amino-Antipyrine and Shrunk Body Weight in Predicting the Chemical Composition and Energy Value of the Sheep Body

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Abstract
Antipyrine (AP) and N-acetyl 4-amino-antipyrine (NAAP) water spaces were determined in 65 sheep used in a feeding experiment designed to determine the net energy of three feeds (chopped hay, pelleted finely ground hay and a pelleted mixture of 45% corn meal and 55% finely ground hay) fed at three levels of intake. Following injection of a mixture of the two drugs and subsequent blood sampling necessary to derive the AP and NAAP water spaces, the sheep were slaughtered and their bodies divided in three analytical groups (blood, viscera and carcass) which were ground, sampled and freeze-dried. The 65 sheep studied ranged from 4.9 to 46.6% fat and from 39.6 to 73.8% water on an empty (ingesta-free) body basis. For both age groups studied (15 mo. and 27 mo.), the proportion of the total body water in the gut of sheep fed chopped hay was significantly larger than that of the sheep fed corn-hay pellets. The NAAP space expressed as a percent of empty body water or total body water was not affected by level of intake, kind of feed or age of sheep. The AP space when expressed as a percent of the empty body water was significantly larger for the 15-mo. old sheep (114%) than for the 27-mo. old sheep (108%). Also the sheep fed chopped hay (117.4%) had a significantly larger AP water space than those fed corn-hay pellets. AP space, NAAP space and shrunk live weight (taken after 18 to 20 hr. of fasting) were very highly correlated with empty body water. The correlation coefficients and standard error of estimate were respectively: 0.95 and 1.86 l., 0.94 and 2.01 l., 0.97 and 1.42 l. Consideration of AP and NAAP water spaces in addition to shrunk body weight provided significantly more refinement in the prediction of empty-body water than shrunk body weight alone. The following equation was calculated: Y=1.029+0.298X1+0.178X2+0.222X3; where, X1=AP water space, X2=NAAP water space and X3=shrunk body weight. For this last relationship the correlation coefficient was 0.97 and the standard error of estimate was 1.31 l. for a mean empty-body water content of 19.58 l. The calorific value of the sheep bodies could be predicted from the AP-NAAP measurements with a coefficient of variation of 13.7%. This represented an improvement of 35% as compared with the method in which the energy values were derived from the shrunk body weight alone. There were no significant differences between the AP-NAAP method and the conventional slaughter technique in the net energy values of three feeds. Copyright © 1963. American Society of Animal Science . Copyright 1963 by American Society of Animal Science