In the Czech Republic yeast cultures have recently become an occasional component of feeding rations for cattle. Some papers informed about significant effects of yeast cultures on fermentation under specific anaerobic conditions existing in rumen. Numerous studies (Sune et al., 1998;Alshaikh et al., 2002; Lila et al., 2004 and others) documented positive effects of yeast cultures not only on the rumen environment of dairy cows but also on the improvement of microbial activities. According to Blake (1993), yeast cultures obviously improve the cellulolytic activities of rumen microorganisms in such a way that they increase their total numbers, improve fibre digestion, reduce lactate accumulation, reduce the concentration of oxygen in rumen fluid and improve utilisation of starch supplied in the feeding ration. In this way they influence (inhibit) the rate of VFA production and, thus, increase the stability of rumen environment and improve the intensity of digestion. Sullivan and Martin (1999) also reported that the supplement of a Saccharomyces cerevisiae yeast culture into the diet of dairy cows improved the utilisation of lactate and digestion of cellulose. Lyons (1993) and Strohlein (2003) stated that some yeast strains showed a better capability to use lactate because they stimulated its utilization by propionic acid bacteria. The utilisation of lactate by these bacte- ABSTRACT: This study presents the results of an experiment in which the effect of addition of a yeast culture (Saccharomyces cerevisiae, Strain 47) on rumen fermentation was studied in thirty-six dairy cows of Holstein breed. The animals were divided into one control and five experimental groups. Each group involved 6 individuals. The animals received a diet consisting of good maize silage with a higher dry matter content (16 kg), clover-grass haylage (l6 kg), meadow hay (3 kg) and supplementary feed mixture (7.5 kg). The rations were fed to cows as total mixed ration (TMR). In experimental groups, the yeast culture was added into the feed mixture in amounts of 2, 4, 6, 8, 10 g per day and animal. Samples of rumen fluid were taken perorally 3-4 hours after feeding. The obtained results indicated that the addition of a Saccharomyces cerevisiae SC-47 culture in recommended doses showed a positive effect on ruminal digestion. As compared with control, the addition of all aforementioned amounts of the yeast culture into the feeding ration resulted in all cases in a statistically significant (P < 0.01) decrease in pH and fluctuated near the lower limit of the reference values. As compared with control, the yeast culture supplementation showed a positive effect (P < 0.01) on production of volatile fatty acids (VFA) (127.6 vs. 84.0 mmol/l). The utilisation of ammonia was higher (P < 0.01) in experimental groups (8.12, resp. 8.68 mmol/l) than in controls (9.06 mmol/l). The difference in protozoa numbers in rumens of dairy cows in the control and experimental groups was statistically highly significantly (P < 0.01) different. There was a close relation...

Abstract:The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed.

Effects of 1, 3, 5 or 7% of linseed oil in the diet on the content of fatty acids in breast and thigh meat were studied in broiler chickens. Oils made either of seeds of the linseed cultivar Atalante (A) with a high content of α-linolenic acid or of the cultivar Lola (L) with a predominating content of linoleic acid were fed from 25 to 40 days of age. When feeding A, the contents of all n-3 polyunsaturated fatty acids (PUFA), including eicosatrienoic acid, were significantly higher, those of n-6 PUFA were lower, and the ratio of n-6/n-3 PUFA was narrower (P < 0.001) than when L was fed. The narrowest n-6 to n-3 PUFA ratio was observed at the content 36 g of α-linolenic acid (58 g A) per kg of the diet while the widest one at 2 g of α-linolenic acid (70 g L) per kg of the diet. When using L, the increasing level of linoleic acid in feed was associated with significantly increasing levels of all n-6 PUFA in meat. The content of all n-3 PUFA increased after the application of oil A, but the dependence for eicosapentaenoic acid in thigh meat was expressed significantly more precisely by the second degree parabola with the maximum at the level of 37 mg of α-linolenic acid and for clupanodonic and docosahexaenoic acids by parabolas with maxima at the level of α-linolenic acid in the diet 41 g and 30 g for breast meat and 35 g and 27 g for thigh meat, respectively. By means of the inclusion of linseed oil with a high content of α-linolenic acid in the feed mixture it would be possible to produce poultry meat with a high content of n-3 PUFA as a functional food.

The epidemiology of potato late blight (Phytophthora infestans) was observed over the three-years with 110 potato varieties from various maturity groups treated or not treated with fungicides. The determined severity values were transformed into AUDPC coefficients characterizing rate of disease spreading across the crop in connection with varietal characteristics, fungicide application and year effects. The analysis of the pathogen population for the distribution of races virulent to usually used resistance genes indicated non-efficiency of these genes; resistance could only be increased by breeding for polygenically determined horizontal resistance. There were important yearly variations observed for the epidemiology of P. infestans. A correlation was detected between increasing AUDPC value and yield reduction in both fungicide treated and non-treated variants. AUDPC value of the treated variant is to a certain extent positively correlated with the value of the non-treated variant. However, particular interaction between potato genotype and applied fungicide program was shown, which could positively or negatively affect disease course in dependence on the variety.

Broad-leaved dock is together with creeping thistle (Cirsium arvense (L.) Scop.) and dandelion (Taraxacum officinale Wigg.) one of the most frequently occurring grassland weeds in the Czech Republic (Martinková and Honěk, 2001). Broadleaved dock belongs to the group of plants with the highest requirement for nitrogen and other nutrients. Its ecological requirements and herbage quality differ only li�le from those of curled dock (Rumex crispus L.) and the two species can therefore be assessed together (Weissbach, 1998). According to Klimeš (1993), there are also unfertile hybrids of the two species occurring in grass stands, referred to as R. ×pratensis. These species represent aggressive plants which force cultural grasses and legumes out from their surroundings and cause problems at herbage conservation due to their low DM contents. Humpreys et al. (1999) demonstrated that grazed swards in Britain were related to a higher mortality of docks as compared with mown swards due to lower doses of applied fertilisers, increased defoliation and trampling. High doses of N-fertilisers were put into connection with higher occurrence of Rumex obtusifolius. Novák (1994) described associations with dominating broad-leaved dock at grazing sites overfertilized with animal excrements, which can be long without any change in the species composition and which are avoided by grazing animals. In the system of organic agriculture the broad-leaved dock is a very serious problem as it cannot be controlled by herbicides and docks markedly reduce the sward nutritive value (Pötsch, 2000).With respect to the fact that sward herbages are fed on most farms in the form of grass silages, it is vitally important to know individual factors affecting their nutritive value and also the quality of fermentation process during their production. The effect of broad-leaved dock (Rumex obtusifolius L.) on the impaired nutritive value of grassland herbages was studied together with the effect of dock and addition of microbial inoculant on the fermentation process in grass silages. The herbage of broad-leaved dock exhibits low DM content, CP and fibre contents comparable with red clover, yet its NEL concentration is low. Quality of silages made of dock at DM content over 300 g/kg is good but the silages show significantly lower contents of lactic acid (35.9%), acetic acid (70.0%) and higher pH values (4.69 vs. 4.35) as compared with the grass silage. Silages made of dock do not contain butyric acid and exhibit lower rates of proteolysis. The presence of broad-leaved dock in herbage poses a danger of slow wilting and low production of fermentation acids. The addition of lactic acid bacteria (LAB) showed in the studied set of silages and in dock silages by an increased content of lactic acid (+18.9% and +27.0%, resp.) and by a significant reduction of pH value (-0.17 and -0.14, resp.).

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.

Mycotoxins are secondary metabolites produced by fungal species that have harmful effects on mammals. The aim of this study was to assess the content of mycotoxins in fresh-cut material of selected forage grass species both during and at the end of the growing season. We further assessed mycotoxin content in subsequently produced first-cutting silages with respect to the species used in this study: Lolium perenne (cv. Kentaur), Festulolium pabulare (cv. Felina), Festulolium braunii (cv. Perseus), and mixtures of these species with Festuca rubra (cv. Gondolin) or Poa pratensis (Slezanka). The mycotoxins deoxynivalenol, zearalenone and T-2 toxin were mainly detected in the fresh-cut grass material, while fumonisin and aflatoxin contents were below the detection limits. July and October were the most risky periods for mycotoxins to occur. During the cold temperatures in November and December, the occurrence of mycotoxins in fresh-cut material declined. Although June was a period with low incidence of mycotoxins in green silage, contents of deoxynivalenol and zearalenone in silages from the first cutting exceeded by several times those determined in their biomass collected directly from the field. Moreover, we observed that use of preservatives or inoculants did not prevent mycotoxin production.