Use of fibrolytic enzymes produced by the fungus Thermomyces lanuginosus in ruminant nutrition

Abstract

A strain of Thermomyces lanuginosus NCAIM 001288 was used to produce an enzyme preparation. The obtained product (RuminoZyme) contains thermally resistant endo1,4betaxylanase with 250 FXU/g activity. Investigations focused on the efficiency of the xylanase product from T. lanuginosus in ruminants. In the first trial we characterised the stability of the xylanase preparation in the rumen of merino wethers. A single dose of 10 g enzyme preparation applied directly into the rumen increased the baseline xylanase activity of the rumen fluid by about 300 % within 5 min after treatment. Total xylanase activity of the rumen decreased to only 63% till the 45th min. After 60 and 90 min the original enzyme activity decreased to 41% and 34%, respectively. Between 90 and 120 min after treatment the enzyme activity settled at a level, slightly over 30% of the original. Three hours after treatment no increment in the enzymatic activity was seen and the activity returned to initial values. In our second trial the effects of the enzyme product on rumen fermentation characteristics of merino wethers were measured. Adding 2.5 g/sheep/day enzyme preparation to the sheeps’ diet had increased the xylanase activity of the rumen fluid in the experimental group compared to the control. There was no change in the pH value of the rumen fluid. Total VFA concentration was higher after feeding in the enzyme supplemented period compared to the control. The molar proportion of acetate was affected by the enzyme supplementation, it was higher in the experimental period than that in the control. The molar ratio of propionate tended to be higher in the enzyme supplemented period but it did not differ significantly from the control. The molar ratio of butyrate was significantly lower then control values in the experimental phase. Ammonia concentration of the rumen fluid was lower in the experimental period than in the control 4 h after feeding. In our third experiment the effects of the enzyme preparation from T. lanuginosus were studied on ruminal VFA concentration, parameters of energy and protein metabolism, milk yield, feed conversion ratio and body condition score of high yielding dairy cows in early lactation (from calving to 110th DIM). The preparation administered in a dose of 30 g/cow/day increased TVFA concentration in the rumen fluid. The milk yield significantly increased in the enzyme supplemented group. There was a better balanced energy metabolism in the experimental cows as indicated by lower incidence rate of hyperketonaemia and lower acetoacetate and NEFA concentration in the blood and plasma samples. Feed intake and feed conversion rate were also better in the experimental group. Due to the better balanced energy metabolism postparturient body condition loss of the enzyme treated cows was reduced. In our fourth trial the effects of the directfed NSP degrading enzyme preparation were evaluated on the health, milk yield and milk quality of dairy cows in midlactation. As a result of this experiment we can conclude that there were no significant differences between the experimental and the control group regarding major blood and urine parameters which are in strong correlation with the health status. Thus enzyme supplementation presumably did not have an adverse effect on the health of the animals though it did not improve metabolic parameters. Our results indicate that feeding NSP enzyme supplement to cows in midlactation cows do not improve milk and FCM yield, milk fat and milk protein content significantly. Advantages of oral administration of exogenous enzymes to cows in midlactation are uncertain and it is always necessary to calculate the economic benefits.