Comparison of in vivo with in situ mobile bag and three step enzymatic procedures to evaluate protein disappearance of alfalfa hay and barley grain

Ruminal, post-ruminal and total tract crude protein disappearance of alfalfa hay and barley grain were measured using in vivo, in situ mobile bag and three-step in situ/in vitro enzyme procedures (3-step). For in vivo, four Baluchi lambs (49.4 ± 3.5 kg, body weight) were used in a 2 × 2 Latin square design within 2 periods (24 days of each period). Experimental diets were made of two alfalfa hay: barley grain ratios (DM basis) as 1.0:0.0 and 0.5:0.5. Diets were fed to animals for 24 days, with 7 days of feces collection. In situ mobile bag technique was followed by 12 h rumen incubation and then intestinal movement of the bags in rumen and post-rumen cannulated Holstein steers. The three-step procedure was followed by rumen incubation of samples for 12 h (using polyester bags) and enzymatic incubation of ruminal undegradable samples. In vivo total tract crude protein disappearance of alfalfa hay and barley grain (0.74 and 0.69, respectively) was significantly (P