An experiment was carried out on four dry Holstein cows fitted with rumen cannulas that were divided into two groups. The crossover design experiment was divided into 4 periods of 3 weeks. Each period consisted of a 17-day preliminary period followed by a 4-day experimental period. Cows were fed twice daily the total mixed ration based on maize silage and concentrate. Control cows (Control) received the basal diets while experimental animals (Yeast) received the basal diet supplemented with 3.0 g of live yeast (BIOSAF Sc 47, Lesaffre, France) at each feeding. During each experimental period ruminal pH and redox potential (Eh) were monitored continuously using a developed wireless probe. Further, in each experimental period five samples of ruminal fluid were taken at 6:30, 8:30, 10:30, 13:30 and 16:30 h to determine the content of volatile fatty acids, lactic acids and ammonia. On the last day of each period, blood samples were taken for determination of blood parameters and acid-base balance. Average daily dry matter intake throughout the experiment was 8.2 kg/day and was not affected by the treatment. The average ruminal pH in Control was 6.16 that was significantly lower than in Yeast, being 6.26 (P < 0.001). The diurnal pattern of ruminal pH showed a similar trend in both groups. Mean Eh in Control (-210 mV) differed significantly from Yeast (-223 mV, P < 0.001). The mean value of rH (Clark's Exponent) calculated for Control (5.33) was higher than that calculated for Yeast (5.09, P < 0.001). Total VFA concentrations were on average 40.8mM in Control and 57.2mM in Yeast (P > 0.05). Lactate and ammonia concentrations at individual sampling times and overall mean did not differ significantly between treatments (P > 0.05). Blood pH and CO 2 were not affected by the treatment.

ABSTRACT:The objective of this study was to determine the effect of supplemental lysine (Lys), methionine (Met) or both amino acids added in the form of rumen-protected (RP) tablets with copolymer coating to a diet of dairy cows on yield and composition of milk and concentration of plasma amino acids (AA). The experiment was carried out on four high-yielding lactating Holstein cows with average milk production of 33.5 kg/day in the form of Latin square design. The four treatments were as follows: C -control without AA supplementation, L -control plus supplement of RP Lys, M -control plus supplement of RP Met and ML -control plus supplement of RP Met and Lys. The experiment was divided into 4 periods. Each period (14 days) consisted of 10-day preliminary period and 4-day experimental period. Cows were fed a diet based on maize silage, lucerne hay and supplemental mixture. Average milk yield recorded in ML was 34.18 kg and was higher than that recorded in L or M (32.46 kg and 32.13 kg, respectively P < 0.05) and tended to be higher than in C (33.33 kg, P > 0.05). The content of protein and casein was higher in L and ML in comparison with C (P < 0.05) and tended to be higher than in M (P > 0.05). Protein yield in ML (1 054 g/day) was higher than that found in C, L or M (990, 998 or 968 g/day, respectively, P < 0.05). The same response was found for casein yield (P < 0.05). Although the proportion of individual casein fractions was not affected by the treatment, the yield of α-and β-casein differed (P < 0.05) while the yield of κ-casein was not affected by the treatment. Concentrations of blood metabolites, except for betahydroxybutyrate (BHB), were not changed. Plasma Met concentrations were increased (P < 0.05) in the M and ML group. Similar, but insignificant increases (P > 0.05) were also observed in plasma Lys in the L and ML group.

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In cattle feedlots, the manure builds up and to some extent becomes incorporated into the soil profile through downward leaching and the stirring action created by the cattle. The object of this study was to measure the extent of build‐up of certain chemical elements resulting from the cattle wastes within the soil profile (Felda fine sand) in a cattle feedlot after 10 and 15 y. Soil samples were taken at 15‐cm increments from the soil surface to a depth of 137‐cm. Results indicated most of the increase of elements occurred near the soil surface. Within the soil profiles, the magnitude of increase of the chemical measurements compared with the control profile after 10 and 15 y were as follows, respectively: Mg, 23 and 39 times the amount in the control profile; P, 50 and 95; Ca, 11 and 29; K, 133 and 85; Mn, 4.4 and 9.5; Fe, 1.4 and 1.3; Cu, 2.5 and 4.2; soluble salts, 5.9 and 8.6; and percent organic matter, 1.6 and 5.1 times the amount in the control profile. The range of soil pH values increased from 3.6 to 4.7 for the control; from 7.8 to 9.1 after 10 y, and from 8.3 to 8.7 after 15 y.

Digestibility is an important factor of the nutritive value of feed. Digestibility determines the relation between contents of nutrients and energy that are available to ruminants. Chemical composition of feed provides information about physical properties and quality of feed and is used to derive digestibility and expected performance of the ruminant receiving the feeds (Expert Committee on Animal Nutrition, 1986).Cell content includes carbohydrates, organic acids, lipids, proteins, nitrogenous substances and most of inorganic constituents. Digestibility of organic matter includes digestible cell content and digestible cell wall content. While cell content is digestible from almost 100%, the level of cell wall degradation is different. Digestibility of organic matter has a negative correlation with NDF, ADF and hemicelluloses. A significant negative correlation was found between digestible organic matter and NDF (%) in organic matter (Čerešňáková et al., 1996).The nutritive value of forages for ruminants depends on the ability of rumen microorganisms to degrade the plant cell wall and to ferment available carbohydrates. Simple prediction methods are required for practical use. Many attempts have been made to predict the nutritive value from chemical composition, using enzyme or rumen liquor. Such data are only valuable if equations are used for the calculation based on in vivo digestibility data for the same type of feed grown in the same environment (Vencl, 1990). A technique using rumen liquor developed by Tilley et al. (1961)