Effect of different source of lipid on gas production and degradabiliy of dry matter, neutral detergent fiber and crud protein determined with in Sacco and in vitro technique

Abstract
Background and objectives
Fat is one of the most important nutrients in ruminant’s nutrition and its fate in the fermentation medium and rumen, is effective in the efficiency of feed usage. Awareness of digestibility and energy production of feeds and determine degradability of dry matter, neutral detergent fiber (NDF) and crude protein as a measurable nutrient, is valuable for formulating of balanced rations and correct understanding of degradability mechanism, digestion and uptake of nutrient for increase efficiency and income of farmers. In last of 1970 measure of gas production via incubation of feeds in buffered rumen liquid for assaying of digestibility properties of diets and fermentation kinetics were started with in vitro method. Whereas disappearance of dry matter, NDF predicted with nylon bag technique. In this experiment effect of different source of lipid on gas production (in vitro), dry matter, NDF and crud protein degradability (in Sacco) were assayed. Correlation coefficients of two experiment parameter were analyzed with Pearson method.
Material and methods
Two experiments were conducted to assess the fate and behavior of feed and the kinetics of digestion of three fat sources. In the first experiment, the amount of gas production from the digestion of four experimental treatments include : 1) no added lipid source (control) and 2, 3 and 4) with 5% calcium fatty acid, animal fat and rapeseed oil, respectively, incubated in rumen fluid, was measured with in vitro method. In the second trial 4 rumen fistulated Dalagh rams were allotted for measuring degradability parameters. In the second experiment, rumen fistulae male sheep were used to determine the biodegradability components of dry matter, fiber and crude protein in the above treatments by nylon bag method. Finally, the results of correlation between the two experiments were analyzed by Pearson method.
Results
Gas production at the first 2 h of incubation was higher than other the lipid content treatments, not significant at 24 h and was significant at 96 h in the lipid source treatments than the control treatment. Organic matter digestibility, short chain volatile fatty acids production, and metabolizable energy in the gas test were significantly higher in the calcium fatty acid treatment than control, animal fat and rapeseed oil treatments (P <0.05). The dry matter degradability of calcium fatty acid treatment was more than other fat sources (P = 0.01). Crude protein degradability potential and fiber degradability were not significantly affected by different fat sources (P = 0.07). Degradability of NDF decreased slightly by adding fat sources. In this experiment, high correlations were observed in estimation of biodegradability and prediction parameters of dry matter, crude protein and NDF in experimental treatment in gas test and nylon bag technique.

Conclusion
Results of this study showed that gas production and biodegradability were different in treatments containing lipid sources. Diets containing protected fat with higher digestibility, produced more short chain fatty acids, higher metabolizable energy, and greater gas at 96 h after incubation in rumen fluid than animal fat and vegetable oil containing treatments. The highest effective degradability was observed at 5% flow level for dry matter, crude protein and NDF. All of these results indicate that incorporation of energy source with lipid sources especially protected fat has no adverse effect on fermentation and its use has increased fermentation efficiency. On the other hand, a high correlation was observed between the parameters of gas test (SCFA, ME and organic matter digestibility) and nylon bag technique (a, b and c) with Pearson method. Furthermore, gas test can be used with high efficiency to evaluate the lipid source added rations be instead of the costly method of nylon bag technique.