Study On Factors Affecting Rumen Fermentation Of Maize Straw By Gas Production Technique In Vitro

In this paper, three two-year old Xinjiang Kazak wethers fitted with permanent ruminal cannulas were used as rumen liquor donors. Three experimental serials were conducted:Serial Ⅰ: Studies on gas production technique in vitro A gas production apparatus has been designed to study on maize straw fermentation in vitro. Maize straw 8.523g(on a dry matter basis) was incubated with rumen liquid (90ml) and artificial saliva (90ml) for 36hr. Fermentation indexes: accumulative gas production (AGP), content of ammonia nitrogen (NH3-N), content of total trichloroacetic acid precipitated protein (TCA-P), concentration of total volatile fatty acids (TVFA), pH and 65℃ dry matter disappearance rate (DMDR) of solid matter in incubators were estimated at intervals of 3hr up to 36hr. Variable regulation between fermentation parameters and time were given. Correlation between 65℃ dry matter disappearance rate and other fermentation parameters was analysed. Three regression models were also established. According to the results, the incubation time of maize straw should be 24hr as the longest and 15hr as the shortest.Serial Ⅱ: Studies on nutrient additives Urea, sulphur, phosphorus, mixed trace elements, Vitamin C, Vitamin A and maize powder as nutrient additives were studied on the fermentation of maize straw by using serialⅠ's technique. Results showed that AGP and 65℃ DMDR of 24hr increased by 7.0% (p<0.01) and 5.2% (p<0.01), respectively, in the urea and maize straw incubation group compared with the control group. As long as the maize was concerned, the two fermentation parameters increased by 7.8% (p<0.05) and 11.7% (p<0.01), respectively. The other nutrient additives affect the fermentation of maize straw, but not at significant level.Serial Ⅲ: Studies on non-nutrient additives β-agonist, bentonite, formaldhyde, oxytetracycline and ammonium Madumeisu as non-nutrient additives were studied on maize straw fermentation by serialⅠ's technique. Results showed thatβ-agonist and bentonite increased the concentration of TVFA in maize straw incubation liquid significantly (p<0.05); formaldhyde, oxytetracycline and ammonium Madumeisu restrained the rumen fermentation of maize straw in vitro, three of which significantly decreased 65℃ DMDR and restrained the product of gas from maize straw fermentation, separately.