As is known, the digestibility of feedstuffs is affected by many factors. Llano states that the ratio of roughage and concentrate in the ration, the physical form and quality of the feeds are the most important of these factors, and suggests that when given on the maintenance allowance, the digestibility of poor quality feeds decreases more than that of good quality ones, and that as the ratio of concentrated feed in the ration increases, the digestibility of roughage decreases. Thomas states that barley pulp and water reduce digestibility and feed consumption due to some substances they contain.

Protein Digestibility:

Recent studies on barley pulp focus on the protein digestibility of barley pulp, and the effects of the digestibility rate in the rumen on productivity in ruminants are investigated.

Armentano et al. , indicates that when dairy cattle rations are supplemented with easily degradable protein sources, the rate of protein breakdown in the rumen exceeds the rate of protein synthesis, which causes inadequate use of feed nitrogen and absorption in the form of ammonia, and suggests that protein sources resistant to breakdown in the rumen positively affect milk yield by increasing the amount of protein passing to the duodenum. In a study conducted with dairy cattle, Seymour and Polan supplemented the protein deficiency of low and high energy rations with soybean meal or barley pulp. The results of the study show that although no difference was seen in the high energy ration, milk yield was higher in the group given barley pulp in the low energy ration. The researcher attributes this to the fact that barley pulp contains more protein resistant to breakdown in the rumen and passing to the duodenum, which increases tissue mobilization.

It is stated that using barley pulp instead of soybean meal in fattening cattle increases live weight gain and feed utilization, and the reason for this is shown to be the low protein digestibility in the rumen of barley pulp.

Many researchers agree that the low protein digestibility of barley pulp in the rumen has a positive effect on productivity and feed utilization.

It is known that protein digestibility in sheep is much higher than that of meadow grass.