In situ Ruminal Degradation of Dry matter and NDF and Gas Production Parameters of Cottonseed hulls Treated with Sodium Hydroxide

The objective of this study was to determine the digestion and gas production potential of sodium hydroxide treated cottonseed hulls using in situ and in vitro procedures. Cottonseed hulls were treated using 2 and 4 percent solutions of sodium hydroxide and then kept for 0.5 and 48 h. For in situ procedure, 5 g of each sample was weighed into a polyester bag and incubated in the rumen of three ruminally fistulated sheep. After each time of incubation, bags were removed and rinsed with cold tap water. The residual of dry matter and neutral detergent fiber was determined. For the gas production technique (in vitro), approximately 0.3 g of each sample was placed in a 100 ml glass syringes then incubated into 40 ml of buffered rumen fluid (ratio of buffer to rumen fluid was 2:1). The amount of produced gas in each time of incubation in each syringe was accounted for determination of gas production parameters. Results of the in situ technique revealed that alkali treating of cottonseed hulls by a 4 percent solution for 0.5 and 48 h and a 2 percent solution for 48 h caused to a significant increase of the quickly degradable fraction (a) of dry matter (0.057, 0.090 and 0.080, respectively) and neutral detergent fiber (0.076, 0.105 and 0.056, respectively). Alkali treating of cottonseed hulls by a 2 percent solution for 0.5 and 48 h significantly (P<0.05) increased the slowly degradable fraction (b) and fractional constant rate (c) of neutral detergent fiber (0.673 and 0.887, respectively). Gas production parameters of cottonseed hulls did not alter when treated with different sodium hydroxide solutions.