Intake, microbial protein synthesis, and nitrogen balance in lambs fed diets containing mulberry hay

The objective of this study was to evaluate intake, microbial protein synthesis, and nitrogen balance in lambs fed diets containing 0.00, 12.50, and 25.00% mulberry hay substituting the concentrate. Twentyfour Ile de France lambs at approximately 60 days of age, with a body weight of 15.48 ± 0.07 kg, were confined in individual stalls and slaughtered upon reaching 32 kg body weight. Only the intakes of ether extract and metabolizable energy decreased linearly (P<0.05) as the participation of mulberry hay in the concentrate was increased. Nitrogen in the feces, expressed in g day-1 and g kg0.75 day-1, increased linearly (P<0.05), whereas excretions (mmol day-1) of allantoin, total purines, and absorbed microbial purines, microbial production (g day-1) expressed in microbial nitrogen and microbial crude protein, and microbial efficiency expressed in g MN kg-1 RDOM-1 and g MP kg-1 of TDN decreased linearly as the level of hay in the diet was increased. Mulberry hay substituting the concentrate in diets for feedlot lambs reduces the microbial protein synthesis.