Abstract :
Data from 44 studies with 243 treatment mean observations, representing 2476 goats in various stages of lactation, were
used to estimate the requirement and efficiency of use of ME for milk production. Development and evaluation data subsets
comprised, respectively, 68 and 32% of observations. ME intake was also adjusted for energy lost in excretion of excess
nitrogenous compounds in urine (MEExN), as 62.21 kJ/g of N intake above endogenous urinary N (0.165 g/kg BW0.75).
AdjustedMEintake was partitioned into that used for maintenance and activity in pen or stall settings (MEm; by two methods),
ME secreted in milk and ME gained as BW. For Method 1, MEm = 1.1×315 kJ/kg BW0.75/km, with km or efficiency of ME
use for maintenance = 0.503 + (0.019×ME,MJ/kg DM). For Method 2, estimates of MEm in a companion study for dairy
(501.3 kJ/kg BW0.75) and other goat biotypes (422.7 kJ/kg BW0.75) were used. When BW increased, ME intake was adjusted
for tissue accretion (efficiency= 0.75) to derive dietaryMEused in milk secretion (MEl-d). Milk yield was corrected to 4% fat
[4% FCM;MJ/kg= 1.4694+ (0.4025×%milk fat)]. For does decreasing inBW,FCMfrom the diet (FCMd)was estimated by
adjusting for use of mobilized tissue energy (23.9 kJ/g; efficiency= 0.84).Noparticular equations explained considerably more
variability in observed FCM or NE for lactation than other equations. Based on no-intercept regressions (MEl-d against FCMd)
with Method 1, the dietary ME requirement for lactation was 4598 (S.E. = 106.6) and 4937 (S.E. = 106.5) kJ/kg FCM with
and without adjustment for MEExN, respectively. With Method 2 and no-intercept equations, the dietary ME requirement for
lactation was 4882 (S.E. = 105.2) and 5224 (S.E. = 105.8) kJ/kg FCM with and without adjustment for MEExN, respectively.
Prediction accuracy was similar between methods and improved slightly by correction for ADG. In conclusion, with the large
amount of data employed in this study, these estimates and this factorial approach seem useful to predict energy requirements
of lactating goats, with potential for future enhancements based on research of the factorial approach assumptions.
© 2004 Elsevier B.V. All rights reserved.
