Effects of an enzyme mixture on in vitro digestibility of some by products

Background and objective: 

Increasing of livestock population has resulted in shortage of feed sources and competition between humans and animals. These problems have led to increasing concern in using by-products in animal feeding. But, most by-products have a low nutritional value due to the presence of high concentrations of lignocellulosic compounds and intermediate metabolites. In such a situation, a good solution is to use different processing methods to increase the nutritional value of these compounds or to use commercial enzyme mixture in animal fed. The aim of this study was to determine chemical composition of some agricultural by-product and also to the test the effect of a commercial enzyme mixture on their in vitro fermentation characteristic using gas production technique.

Material and methods: 

Soybean hull was provided from a soybean processing factory and pistachio hull and sugar beet pulp were provided from a local farm. In the laboratory soybean hull divided in to batch and one of them was under wind blowing separate soybean hull from cracked bean to produce bean-free soy hull. All samples were analyzed in duplicate for kjeldahl nitrogen, organic matter, neutral detergent fiber and acid detergent fiber. Gas production test was performed and metabolisable energy, digestible organic matter and volatile fatty acids were estimated. About 200 mg of each were incubated in 100 ml glass syringes and 30 ml of incubation liquid were added and were incubated in 39 C° water bath. The amount of enzyme was 0.05 %. The gas production was measured in 2, 4, 8, 12, 24, 48, 72, 96, 120h. The results were analyzed in completely randomized design.

Results: 

Greatest content of crude protein and lignin were measured in soybean hull (20.49 % of Dry Matter) and pistachio hull (8.55 % of Dry matter), respectively. High amount of non-fiber carbohydrate were noted in pistachio hull and sugar beet pulp. Enzyme had no effect on gas production in different hours, cumulative gas production, and the rate of gas production, organic matter digestibility, metabolisable energy and volatile fatty acids.

Conclusion: 

Pistachio hull and sugar beet pulp had a large amount of non-fibrous carbohydrates and both soybean hull and sugar beet pulp had a small amount of lignin. Appling enzyme in the recommended dose did not have any effect on the fermentation parameters, digestible organic matter, metabolisable energy and chort chain fatty acids. For future studies, using higher doses of the enzyme mixture and different times of enzyme application be suggested. Key words: By products, exogenous Enzyme, Gas production, Volatile fatty acid.