Prediction of energy requirements for maintenance and gain of growing goats

J. Luo, A. L. Goetsch, and T. Sahlu

E (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK

Literature data were compiled and a database was constructed to estimate ME requirements for maintenance (ME_m) and BW gain (ME_g) for three different biotypes of growing goats (i.e., > 50% Boer or meat, dairy, and indigenous) by regressing ME intake (MEI, kJ/kg BW^0.75) against ADG (g/kg BW^0.75). Because of differences among biotypes in intercepts and slopes (P < 0.05), data subsets for the different biotypes were used. The meat subset included 60 observations from 11 publications, representing 548 goats; there were 116 observations from 25 publications with 1,851 goats in the dairy subset; and the indigenous subset had 157 observations from 34 publications and 1,024 goats. Dairy and indigenous subsets were split into two groups-one for equation development and a second for evaluation. Observations with residuals greater than 1.5 times the residual SD from initial regressions were deleted. Equations were meat: MEI = 457.0 (SE = 22.3) + (25.23 (SE = 1.74) x ADG) (n = 57; R² = 0.79); dairy goats (development subset, n = 63): MEI = 573.7 (SE = 46.2) + (23.56 (SE = 3.10) x ADG) (n = 56; R² = 0.52); and indigenous (development subset, n = 87): MEI = 500.0 (SE = 11.9) + (18.59 (SE = 1.64) x ADG) (n = 76; R² = 0.63). Intercepts and slopes from regressions of observed against predicted MEI with evaluation subsets based on dairy and indigenous equations were not different from 0 and 1, respectively. Prediction equations for the three biotypes had similar slopes, but the intercept for dairy differed (P < 0.05) from those for meat and indigenous. A common slope equation with a dummy variable (D; dairy = 1 and others = 0) was: MEI = 480.0 (SE = 13.5) + (103.2 (SE = 17.4) x D1) + (22.85 (SE = 1.23) x ADG) (n = 189; R² = 0.74). In conclusion, based on a compiled database from publications with growing goats, ME_m was 583.2 kJ/BW^0.75 (139 kcal/kg BW^0.75) for dairy goats and 480.0 kJ/BW^0.75 (115 kcal/kg BW^0.75) for meat and indigenous goats, and ME_g was 22.85 kJ/g (5.46 kcal/g). Supported by USDA project No. 9803092.