Effects of sun-drying and exogenous enzymes on nutrients intake, digestibility and nitrogen utilization in sheep fed Atriplex halimus foliages

Abstract

This study was conducted to assess effects of sun-drying and/or addition of an exogenous enzyme (ENZ) preparation on intake, digestibility of nutrients and recovery values of secondary metabolites (SM) in the gastrointestinal tract of sheep fed Atriplex halimus (AH) foliages. A randomized block design for 28 d was used for four experimental treatments based on either fresh (AH-F) or sun-dried (AH-S) A. halimus foliages in the absence (−ENZ) or presence (+ENZ) of 10 g/sheep/d of the exogenous of ZADO® enzyme preparation. Three adult sheep weighing 51 ± 2.7 kg were fed for each experimental treatment. The ENZ was added daily with a small amount of concentrate to help balance the dietary metabolizable energy concentration. Nutrient intake and digestibility, N balance and recovery of SM (i.e., total phenolics (TP), saponins (SP), alkaloids (AK), aqueous fraction (AF)) in the gastrointestinal tract were determined. Levels of most nutrients did not differ between AH-F and AH-S foliages, but the AH-S contained less than half of the SM in AH-F. Drying of A. halimus and ENZ addition increased (P=0.001) intake as well as OM and NDFom digestibility (P=0.02). Feed intake and digestibility were higher (P=0.01) in AH-S with ENZ addition. Intake of N by sheep fed the treatment diets depended on DM intake as the dietary concentration of N in the diets was similar. Thus AH-S sheep supplemented with ENZ had higher (P=0.001) N intake. Digestibility of N was similar to DM and OM digestibility, and was higher (P=0.03) in AH-S sheep supplemented with ENZ. Drying and ENZ addition to the diet increased (P=0.004) recovery of all SM. The fate of these compounds in the rumen needs to be evaluated considering that SM have been implicated in fiber and protein degradation in the rumen. The study showed that there are beneficial impacts of sun-drying and/or dietary exogenous enzyme addition for sheep fed A. halimus.