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The experiment was conducted to evaluate the effect of yeast culture (Saccharomyces cerevisiae) supplementation on ruminal fermentation in 20 Holstein dairy cows divided into control and experimental groups, each group of 10 cows. The animals received a diet based on maize silage (19 kg), alfalfa silage (15 kg), meadow hay (1.5 kg), extracted rapeseed meal (1 kg) and concentrate mixture (9.5 kg). The diets were fed as a total mixed ration. ) was added to the concentrate mixture in the ration fed to the experimental group of animals. The addition of yeast culture significantly (P < 0.01) increased ruminal pH but had no positive effects on the increased production of volatile fatty acids. The supplementation of yeast culture significantly (P < 0.01) increased numbers of protozoa in the rumen of dairy cows of the experimental group (361.3 ± 18.315) compared to the control group (308.3 ± 37.505). The addition of yeast culture significantly (P < 0.01) increased concentration of serum glucose, calcium, phosphorus, copper, zinc, magnesium and AST (P < 0.05). As compared to the control group (4.948 ± 0.0384 mmol·l -1 ), the level of urea in the blood serum was significantly decreased (P < 0.01) in the experimental group of cows.Our results show that the supplementation of Saccharomyces cerevisiae culture at recommended doses enhances ruminal fermentation which may have a positive effect on milk production and health status of Holstein dairy cows. Saccharomyces cerevisiae, cows, rumen fluid, blood serum indicatorsYeasts and yeast cultures are frequently used as additives in diets of dairy cows at present. They have a positive influence on fermentation in the rumen, which helps to improve production health and productivity of animals.Results from previous studies on the effect of yeasts on ruminal fermentation and productivity of dairy cows are often ambiguous. The most cited benefit of yeast cultures on ruminal digestion is support of the growth and activity of anaerobic, namely cellulolytic bacteria. Yeasts would utilize residual oxygen introduced into the rumen with feeds, thus contributing to maintain anaerobic environment (Calsamiglia et al. 2006). Moreover, by degrading lyotropic carbohydrates in the rumen, yeast cultures regulate the rate of fermentation, and also by stimulation of lactate-utilizing bacteria yeasts facilitate stabilization of the rumen pH and mitigate its frequent oscillations during the day (Williams et al. 1991). Stable rumen environment is a key factor for achieving optimum milk yields and a good health of animals. However, some authors did not observe any beneficial effects of yeast cultures on dry matter intake or on the milk production and its composition in dairy cows (Cooke et al. 2007). Neither the positive influence of yeast on the digestibility of feeds in the rumen was unambiguously corroborated.Recent studies indicate that yeasts produce also certain low-molecular peptides that simulate the activity of some bacteria species in the rumen (Denev et al. 2007). However, to achieve ...

The aim of this study was to compare 2 dry-cow management strategies and evaluate the effect of shortened dry period strategy on feed intake, metabolism, and postpartum performance of dairy cows in early lactation. Twenty-nine high-yielding dairy cows were divided into 2 groups. The control (CON) group (n=14) was assigned to a traditional dry period of approximately 60 d (57±5.9 d) and was fed a far-off dry cow ration from dry-off to -21 d relative to expected parturition. From d -21 relative to expected parturition, the cows were switched to a precalving ration containing an additional 3kg of concentrates. The cows of the experimental group (n=15) were assigned to a shortened dry period (SDP; 35±6.3 d) and were continuously fed a late-lactation diet from d -60 d relative to expected parturition until calving. After calving, both groups were fed the same lactation diet corresponding to their lactation requirements and cows were followed for 100 d of lactation. Prepartum dry matter intake of the cows assigned to an SDP and fed a late-lactation diet was approximately 4.11kg/cow per day greater compared with the CON group during the 60 d. However, no effect of dry period strategy on postpartum dry matter intake was detected. The cows with an SDP produced approximately 2.78kg/d (6.9%) less milk in the first 100 d of lactation than CON cows; the difference was not statistically significant. No differences were observed in live body weight, body condition score, or back-fat thickness between the treatments. Similarly, no differences existed in concentrations of plasma metabolites. The cows of the SDP group showed lower pH and increased concentrations of lactic acid and volatile fatty acids prepartum than the CON cows. Postpartum concentrations of lactic acid, volatile fatty acids, and NH3 and pH in rumen fluid did not differ between the treatments. Shortening of the dry period did not affect the colostrum quality or birth weights of the calves. Based on the results of this study, a traditional dry period management strategy appeared to be more favorable, considering the dry matter intake and milk production, compared with an SDP and feeding a late-lactation diet throughout the dry period.

AbstrAct:The objective the present study was to determine the influence of a supplemental methionine analogue, the isopropyl ester of 2-hydroxy-4-(methylthio)-butanoic acid, commercially available as MetaSmart TM , on lactation performance, particularly milk protein production. The effects of this preparation were compared with those of a rumen-protected form of methionine, marketed as Smartamine TM M. Experiments were conducted according to a 3 × 3 Latin square design and included 30 high-yielding dairy cows (22 Holstein and 8 Czech Fleckvieh) randomly allocated to three balanced groups. Cows were fed a basal diet based on maize silage, lucerne silage, lucerne hay, fresh brewer's grains, and a concentrate mixture in the form of a total mixed ration ad libitum. The diet M was supplemented with MetaSmart TM (42.5 g/day) and diet S was supplemented with Smartamine TM M (19 g/day), while control diet C contained solvent-extracted soybean meal, which was added to achieve required levels of dietary protein. Each period lasted four weeks in total, including three preliminary weeks and one experimental week during which samples of milk and tail vein blood were taken. Supplementation of MetaSmart TM decreased dry matter intake of cows (18.96 kg) in contrast to the diet containing Smartamine TM M, for which dry matter intake was the highest (20.48 kg; P < 0.001). Despite decreased dry matter intake, the highest average milk yields were recorded for cows supplemented with MetaSmart TM (31.34 kg), which produced by approximately 1.14 kg (P < 0.001) and 0.78 kg (P < 0.01) more milk than cows fed diets C and S, respectively. As expressed by greater ratios milk/DMI, FCM/DMI, and ECM/DMI, the feed efficiency was improved in cows supplemented with MetaSmart TM . Both MetaSmart TM and Smartamine TM M dietary supplementation increased milk yield, milk protein concentrations, and yields and increased the prevalence of β-casein fraction in milk protein.