The role of sugar in the stimulation of microbial protein synthesis in the rumen | Vloga sladkorjev pri spodbujanju sinteze mikrobnih beljakovin v vampu
2006
Znidarsic, T., Agricultural Inst. of Slovenia, Ljubljana (Slovenia) | Verbic, J. | Babnik, D. | Velikonja Bolta, S.
In the article, literature data and results of our own study about the addition of sugars in the ruminant diets are presented. Literature data show that the addition of sugars can improve forage intake, microbial protein synthesis (MPS), efficiency of microbial protein synthesis (EMPS) and, consequently, milk yield and milk composition. The majority of authors recommend that ruminant diet should contain from 50 to 70 g sugars on dry matter basis. Too high sugar content can diminish MPS, EMPS and cause rumen acidosis. The content of sugars in the diet can be increased by ensiling and feeding of grasses with elevated levels of water-soluble carbohydrate. Four growing wethers which were fed a basal diet of grass silage were used in the in vivo balanced Latin square design to study the effect of the addition of sugars on MPS and EMPS. Maize silage, fodder beet and molasses were added to the wilted grass silage (523 g of dry matter kg-1; control). All diets were isonitrogenous, but they differed slightly in the net energy for lactation content (NEL, 6.23-6.43 MJ kg-1 DM) and highly in the sugar content (91-191 g kg-1 DM). Microbial protein synthesis was determined on the basis of purine derivatives in urine. The effect of the addition of sugars was not statistically significant (p = 0.13). The maximal EMPS was achieved with the diet of grass and maize silage (204.1 g kg-1 fermentable organic matter (FOM)), followed by the control ration of grass silage (176.0 g kg-1 FOM), fodder beet (156.6 g kg-1 FOM) and molasses (151.6 g kg-1 FOM). On the basis of literature data and our results it can be concluded that positive effects of the addition of sugars to the basal diet of grass silage can only be expected from direct cut grass silages with small content of sugars in dry matter.
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