Dried lemon as energetic supplement of diet based on urea-treated barley straw: effects on intake and digestibility in goats

Voluntary intake and in vivo digestibility of diets based on treated straw (40 g urea kg−1 straw dry matter) supplemented with dried lemon were determined. Twenty-four castrated male goats of the Murciano-Granadina breed were used in the eight digestion trials. Four digestibility trials with alfalfa hay (100%) and alfalfa hay/dried lemon, untreated or urea-treated barley straw (50:50%) diets were conducted and digestibility by difference of dried lemon, untreated straw and urea-treated straw was calculated. Four trials were conducted using urea-treated straw based diets with dried lemon at four levels of supplementation (0, 100, 200 and 300 g DM per animal per day) in a completely randomized experiment. The urea treatment increased (P < 0.05) the DM digestibility of the straw. Digestible OM intake of supplemented diet increased (P < 0.001) with the inclusion of high levels of dried lemon. DM intake of urea-treated straw decreased (P < 0.01) as the level of dried lemon in the diet increased, but ME intake of the diet was increased (P < 0.01) by dried lemon supplementation ranging from 445.9 to 599.2 kJ kg−1 LW0.75 day−1. DM and OM digestibility of the diets was increased (P < 0.001) by dried lemon supplementation. There were no differences (P > 0.05) in CP, CF, NDF, ADF or cellulose digestibility when the levels of supplement in diets increased. The digestibility of urea-treated straw was determined by difference. In general, a dried lemon supplement had no effect (P > 0.05) on digestibility of the proximate principles or cell wall constituents of the urea-treated barley straw. Results from the present study indicate that dried lemon could be used as a supplement to raise the digestible organic matter concentration of the urea-treated straw based diets without affecting the digestive utilization of the basal roughage. However, a decrease in treated straw intake when the level of supplement in the diet increased was observed.