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  • Author or Editor: Stefania Iwańska x
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When evaluating the effects of yeast culture (Saccharomyces cerevisiae1026) supplied with or without a vitamin premix and mineral bioplexes on some intermediates and end-products involved in the synthesis of milk constituents in 30 early-lactation Black and White Lowland cows, no significant differences were found in the glucose level, mineral contents and enzyme activities of the blood serum. The effect of yeast culture on the availability of minerals for milk synthesis depended upon the dynamics of degradation of mineral bioplexes in the rumen and the cows' mineral status. The insignificant increase found in blood total protein content and the simultaneous small differences in blood urea nitrogen (BUN) and milk urea nitrogen (MUN) values in cows supplied with the yeast culture were probably associated with a high ammonia incorporation into microbial protein in the rumen, which increased protein supply for milk protein synthesis and decreased the nitrogen loss.

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To investigate the milk production limiting potential of a diet based on grass silage (40%), hay (15%), dried sugar beet pulp (13%) and grain compound mixture (32%), 28 multiparous cows in early lactation were randomly assigned to two treatment groups: a control group and a group receiving supplementary rumen protected methionine (RPMet) treatment (12 g intestinally available methionine/ cow/day, given 1–120 days postpartum; Smartamine™; RPAN’s technology). The diet was formulated to meet the requirements for protein and net energy. RPMet supplementation had no significant effect on DMI (kg/cow/day), milk dry mass, milk lactose and milk urea contents. Responses for mean daily milk yield, mean milk fat and milk protein yields were significantly higher (P < 0.05) in cows supplied with RPMet than in controls. Mean daily milk yield, milk protein and milk fat yields increased by 2.4 kg, 108 g and 124 g, respectively. The mean daily milk protein and casein contents were increased by 1.8 g and 0.9 g and milk fat content by 1.2 g in 1 kg of milk, respectively. The results suggest that in cows fed grass silage and a grain compound mixture milk production is limited by methionine insufficiency, but milk production performance can be increased significantly by the addition of RPMet to the diet.

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