Orange leaves and rice straw in the diet of lactating goats: effect on energy balance

摘要

The aim of this work was to determine the effect of horticultural byproducts on energy balance and efficiency of utilization of ME for milk production (kf) of lactating goats. Two isoproteic and isoenergetic (180 g/kg DM and 17 MJ/kg DM) diets were assayed with alfalfa hay as forage source, and peas and horsebean as protein source. A control diet (CON) incorporated barley as energy source (concentrate) and an experimental diet (EXP) replaced barley with orange leaves and rice straw. Ten Murciano-Granadina goats at mid-lactation were used following a cross-over design. Feed intake, refusal, fecal and urine output, and milk yield were recorded daily for 5 d. Then, heat production (HP) was determined during 24 h by indirect calorimetry. Greater ME intake and HP (P<0.05) in CON vs EXP diet were found but k value was not different (0.64 on average). Energy loss as CH4 was lower (P<0.05) in EXP than CON diet. Greater recovered milk energy was obtained in EXP than CON diet. The body retained energy was greater (P<0.05) in CON than EXP diet. The use of the byproducts orange leaves and rice straw improved the energy milk content with no detriment of k_1 value and reduced the CH_4 production in lactating goats.