Abstract :
A database of treatment mean observations from goat feeding/nutrition studies was constructed and used to develop
expressions to describe nutrient requirements of goats. The ME requirement for maintenance (MEm) was 485, 489, 580, 489
and 462 kJ/kgBW0.75, and the ME requirement for gain (MEg) was 13.4, 23.1, 23.1, 19.8 and 28.5 kJ/gADG for preweaning,
growing meat (≥Boer), growing dairy, growing indigenous and mature goats (indigenous and dairy), respectively. The MEm
of mature Angora goats from multiple regression analysis (at 0 tissue gain and clean fiber growth) was 473 kJ/kgBW0.75;
ME requirements for tissue gain and clean fiber growth were 37.2 and 157 kJ/g, respectively. A factorial approach with
linear regression was used to determine the dietary ME requirement for lactation of 5224 kJ/kg 4% fat-corrected milk,
corresponding to an efficiency of ME use for lactation of 0.59. Metabolizable protein (MP) required for maintenance (MPm)
by mature meat, dairy and indigenous goats was determined as the sum of metabolic fecal (0.0267 g/g DM intake for diets
not containing appreciable browse), endogenous urinary (1.031 g/kgBW0.75) and scurf CP losses (0.2 g/kgBW0.6), with an
assumed efficiency of MP use for maintenance protein of 1.0. Based on linear regression of MP intake against ADG, for
growing goats MPm was 3.07 g/kgBW0.75; MP required for ADG (MPg) was 0.290 g/gADG for dairy and indigenous goats
and 0.404 g/gADG for meat goats. The MP requirement for lactation was 1.45 g/g milk protein, equivalent to a milk protein
efficiency of 0.69. The MPm of growing and mature Angora goats from multiple regression analysis (at 0 tissue gain and clean
fiber growth) was 3.35 g/kgBW0.75, and MP requirements for tissue gain and clean fiber growth were 0.281 and 1.65 g/g,
respectively. Identified areas of research that would yield knowledge allowing development of more accurate estimates of
nutrient requirements include composition of accreted and mobilized tissue, effects of stage of maturity and nutritional planeon maintenance energy requirements, energy expenditure due to grazing activity, conditions influencing ruminally undegraded
protein and efficiencies of MP utilization.
© 2004 Elsevier B.V. All rights reserved
