Effects of Processing Methods of Barley Grain and Non-Protein Nitrogen Sources on Rumen Degradability Characteristics, Gas Production and Microbial Protein Synthesis in Afshari Breeding Fattening Lambs

Lack of animal feed, especially with development of industrial methods of animal husbandry waste in many parts of the world, has led farmers and researchers to try identifying and using agricultural and livestock waste and new food sources for animal nutrition, including poultry manure and urea is mentioned in the diet of ruminants. Due to the fact that no research has been done on the effect of barley grain processing methods and non-protein nitrogen sources in the diet on rumen degradability, gas production and microbial protein synthesis in sheep, the present study was conducted.

This experiment was conducted in a completely randomized design with seven treatments including a control treatment containing whole barley grain (without milling) and without urea and chicken manure, treatments 2, 3 and 4 containing processing method of milling, filling and pelleting with a certain level of urea, respectively. (1%) And treatments 5, 6 and 7 containing processing methods of milling, filling and pelleting with a certain level of poultry manure (12%) were performed on sheep. Each treatment consisted of 5 fattening lambs at the age of 3 months 24±1 which were kept individually in separate cages for 14 days of acclimatization period and 84 days of fattening period. In the second experiment, rumen degradability of dry matter, crude protein and NDF of experimental diets were measured using a nylon bag method with 3 fistulated male sheep that were fed in the maintenance level. Extent and rate of gas production were done based on Menk and Stingas. The NH3-N concentration was determined following the Broderick and Kang (1980) technique. Purine derivatives and was measured by the method of Chen and Gomes (1995). Rumen fluid was collected for 5 consecutive days in the end of each period and ruminal fermentation parameters containing pH and NH3-N and were determined. Urine of sheep was collected end of each period for 5 days and microbial protein synthesis was estimated by measuring purine base. Data were analyzed using SAS software version 9.9 (54) using GLM procedure.

The apparent digestibility of dry matter and organic matter were significantly different, and the control treatment (whole barley grain without urea and poultry manure) had the highest apparent digestibility. Digestibility in non-fibrous carbohydrates was significantly different, so that treatment 5 (processing method of milling with poultry manure) had the highest apparent digestibility. Different parameters of degradability of dry matter, crude protein and insoluble fibers in neutral detergent of experimental treatments indicated significant differences between treatments (P<0.05). Barley grain processing with non-protein nitrogen sources caused a significant difference in the fast decomposing part, slow decomposing part and degradable part of dry matter, crude protein and insoluble fibers in the crude protein neutral detergent of experimental treatments. Effective degradability of dry matter, crude protein and insoluble fibers in neutral detergent at 2, 4 and 6% per hour passage rates had a significant difference between experimental treatments. The results showed that there was a significant difference between the experimental treatments in terms of gas production parameters and the amount of gas produced in 96 hours (P<0.05). There was a significant difference between experimental treatments in terms of digestibility of organic matter, amount of metabolizable energy and concentration of short-chain volatile fatty acids. The highest pH was assigned to treatment 7 (6.30) and the lowest pH was assigned to treatment 1 (6.10). Ammonia nitrogen had a significant difference in experimental treatments. The highest ammonia nitrogen was related to treatment 5 (11.45 mg/dL) and the lowest ammonia nitrogen was related to treatment 3 (10.38 mg/dL). The excretion rate of each of the purine derivatives (allantoin, uric acid, xanthine + hypoxanthine) and the total urinary excretion of purine derivatives and the amount of microbial protein synthesized in the rumen were affected by the test diets and the observed difference was significant (P<0.05). There was a significant difference in rumen pH in experimental treatments. The results showed that barley grain processing methods with non-protein nitrogen sources had a significant effect on rumen degradability, gas production, rumen parameters and microbial protein synthesis compared to the control group.

In general, the use of urea (1%) and poultry manure (12%) with different methods of barley grain processing without negative effects on rumen degradability, rumen liquid parameters and gas production in terms of microbial protein synthesis can be useful.