Estimating Methane, Urine, and Heat Increment for Deer Consuming Browse

Abstract

For white-tailed deer (Odocoileus virginianus) consuming woody browse species, significant relationships (P < 0.05) were found to exist among daily energy losses in urine, methane, and heat in- crement and several of the more easily determined measures of the conventional digestion trial. Simple linear regression as well as multiple regression analyses indicated that urine and methane energy losses may both be accurately predicted from conventional digestibility data. The highest correlations were found between urine energy losses and the single variable, fat intake (r - 0.89), and a combination of seven variables (R = 0.98). These regressions had standard errors representing :?_ 14 and ? 9 percent of the estimated mean, respectively. The best fit between methane and a single variable was found with digestible nitrogen-free extract intake (r = 0.72), whereas methane regressed on a combination of five variables had a correlation coefficient of 0.82. Standard errors for these regressions were ? 19 and + 17 percent of the estimated mean, respectively. Several single variables were significantly (P < 0.05) correlated with heat increment, although the highest of these (digestible ether extract) had a correla- tion coefficient of only 0.40. The most highly correlated multiple regression with heat increment was obtained from six variables (R - 0.75). This regression had a SE of 113 or -+-32 percent of the esti- mated mean. Predictive equations are presented for simple linear and multiple regression information on each of the dependent variables.