Abstract :
Databases were constructed to determine ME requirements for maintenance (MEm) and BW gain (MEg) of preweaning,
growing and mature goats by regressing ME intake (MEI) against ADG. Goats were categorized as dairy, meat (≥ 50% Boer)
or indigenous biotypes. The preweaning database included 98 treatment means representing 1016 goats and the growing goat
database consisted of 333 treatment means. Because of differences among biotypes of growing goats in intercepts and slopes
(P<0.05), separate regressions were performed. The meat subset included 60 observations from 11 publications, representing
548 goats; the dairy subset had 116 observations from 25 publications with 1851 goats; and the indigenous subset consisted
of 157 observations from 34 publications and 1024 goats. Dairy and indigenous subsets were randomly split into independent
sets for equation development and evaluation. The mature goat database included 69 treatment means from 23 publications
and represented 495 goats. Small numbers of observations removed after initial regressions to improve fit did not markedly
alter intercepts or slopes. Equations were as follows: preweaning: MEI (kJ/kgBW0.75) = 484.6 (S.E. = 61.46) + (13.37 [S.E.
= 1.95] × ADG [g/kg BW0.75]) (n = 61; R2 = 0.44); meat: MEI (kJ/kg BW0.75) = 457.0 (S.E. = 22.30) + (25.23 [S.E.
= 1.74] × ADG [g/kg BW0.75]) (n = 57; R2 = 0.79); dairy: MEI (kJ/kg BW0.75) = 573.7 (S.E. = 46.20) + (23.56 [S.E.
= 3.10]×ADG [g/kgBW0.75]) (n= 56; R2 = 0.52); indigenous: MEI (kJ/kgBW0.75)= 500.0 (S.E.= 11.94)+ (18.59 [S.E.
= 1.64]×ADG [g/kgBW0.75]) (n= 76; R2 = 0.63); and mature: MEI (kJ/kgBW0.75)= 462.2 (S.E.= 24.95)+ (28.52 (S.E.
= 5.05) × ADG [g/kg BW0.75]) [n = 69; R2 = 0.32]. Intercepts and slopes from regressions of observed against predicted
MEI with evaluation data sets, based on equations for preweaning and growing dairy and indigenous goats, were not different
from 0 to 1, respectively. When final equations for the different growing goat biotypes were tested, the intercept for dairy
goats differed (P < 0.05) from that of meat and indigenous goats, and the slope for indigenous goats tended (P = 0.16) to
differ from that of meat and dairy goats. Therefore, the following dummy variable equation was obtained (I1 = 1 for dairy and
0 for others; I2 = 1 for indigenous and 0 for others): MEI (kJ/kg BW0.75) = 488.5 (S.E. = 14.4) + (91.5 (S.E. = 18.69) × I1)+ (23.09 (S.E. = 1.24) × ADG [g/kg BW0.75]) − (3.28 (S.E. = 1.98) × ADG [g/kg BW0.75] × I2) [n = 189; R2 = 0.74]. In
summary, based on treatment mean observations from available publications and regression of MEI against ADG, MEm was
485, 489, 580, 489 and 462 kJ/kg BW0.75, and MEg was 13.4, 23.1, 23.1, 19.8 and 28.5 kJ/g ADG for preweaning, growing
meat, growing dairy, growing indigenous and mature goats, respectively.
© 2004 Elsevier B.V. All rights reserved
Keywords :
energy requirement , growth , goat , Maintenance