The objective of this study was to examine the effect of microbial oil (MO, n-6 fatty acids) and fish oil (FO, n-3fatty acids) used in their blends as supplements (5% wt/wt) to the diet containing 80% of hay and 20% of barley on rumen fermentation and lipid metabolism in artificial rumen. Overall, three different ratios of n-6 and n-3 fatty acids (1:1, 3:1, and 5:1) as the blends of MO and FO were used. Two similar consecutive experiments were carried out within 2 months. Each experiment lasted for 12 days with 6 days of stabilization period. The addition of all three oil blends did not affect the parameters of fermentation such as degradation of dry matter (DM), detergent fibre, total gas production, but increased the degradation of cellulose and hemicellulose in the diets. The supplementation of oil blends to the diet insignificantly (NS) decreased the methane production (mostly the n-6/n-3 ratio 1:1, about 23.5%), increased (<I>P</I> < 0.01) mol% of propionate (mostly the n-6/n-3 ratio 1:1, about 24.1%) and decreased (<I>P</I> < 0.05) mol% of acetate (mostly the n-6/n-3 ratio, 1:1, about 7.7%). The lipid metabolism in artificial rumen was also affected, when the oil blends increased (<I>P</I> < 0.001) the concentration of total fatty acids (FA) and long-chain FA (LCFA) in effluent. The concentration (mg/g rumen fluid DM) of <I>trans (trans</I> 11 C_18:1, TVA-vaccenic acid), <I>cis</I> C_18:1 isomers and CLA-conjugated linoleic acid (<I>cis</I> 9, <I> trans</I> 11 C_18:2) was also increased (<I>P</I> < 0.001) by the oil blends. Finally, the oil blends caused the incomplete FA biohydrogenation by an increase in TVA concentration and TVA/C_18:0 ratio in effluent in artificial rumen.

ABSTRACT:The rumen simulating technique (RUSITEC) was used to evaluate the effect of dietary inclusion of amaranth seeds on the rumen fermentation and the concentration of fatty acids (FA) in fermentation fluid. Four fermentation vessels of the RUSITEC were used. The control diet (C) consisted of 70% meadow hay and 30% barley meal, whereas 10% of barley meal was replaced by milled (A mill ), mechanically ground (A gr ), and ground after heating in a microwave amaranth seeds (A heat+gr ) in other experimental vessels, respectively. All diets were isonitrogenous (11% of crude protein). With degradability of dry matter (DM) and acid-detergent fibre (ADF) not affected (P > 0.05), degradability of neutral detergent fibre (NDF) was significantly decreased by the inclusion of A mill (P < 0.001) and A heat+gr (P < 0.05). Heating, compared to milling, decreased degradation of crude protein (CP) and addition of amaranth seeds generally increased production of microbial nitrogen. Production of fermentation gasses, methane, and total volatile fatty acids (VFA) was not affected by changes in composition of diets. Addition of amaranth seeds in a milled form (A mill ) caused a significant decrease in concentrations of acetate and propionate and growth in concentrations of butyrate, iso-valerate, and caproate. No effect (P > 0.05), compared to C, was found on the percentage of saturated or unsaturated FA, but changes in concentrations of some FA were observed. An absence of any detrimental effects on ruminal fermentation patterns indicated that grain amaranth seeds can partially substitute for the barley in ruminant nutrition.

Forty samples of grass silages, made from the five most widely used grass species in ruminant nutrition (Dactylis glomerata L., Phleum pratense L., Lolium perenne L., Festuca arundinacea L. and hybrid Felina) were tested in the present study. These grass species conserved by an ensiling process were compared among each other according to dry matter (DM) rumen degradability parameters (a = portion of DM solubilized at initiation of incubation, b = fraction of DM potentially degradable in the rumen, c = rate constant of disappearance of fraction b and ED DM = effective degradability of DM, estimated for each ingredient assuming the rumen solid outflow rates of 0.02 (ED DM2 ), 0.05 (ED DM5 ) and 0.08 (ED DM8 ) h -1 ). Based on the chemical composition of grass silages the regression equations for prediction of ED DM were evaluated. The influence of the ensiling process on dry matter degradability parameters was also assessed. The best values of ED DM were determined for Lolium perenne (ED DM2 = 753.2, ED DM5 = 631.1 and ED DM8 = 567.7 g/kg DM). The best predictor was NDF (R 2 -values of 0.757 (ED DM2 ), 0.863 (ED DM5 ) and 0.906 (ED DM8 )). Using two predictors the accuracy level increased. The combination of CF and NDF gave R 2 -values 0.892, 0.920 and 0.929 for ED DM2 , ED DM5 and ED DM8 , respectively. The regression equations based on the most important grass species harvested in different vegetation periods seem to be a useful tool for practical use. No significant (P < 0.05) effect of the ensiling process in relation to dry matter rumen degradability parameters was proved.

Loučka R., Tyrolová Y., Jančík F., Kubelková P., Homolka P., Jambor V. (2018): Variation for in vivo digestibility in two maize hybrid silages. Czech J. Anim. Sci., 63, 17-23.The experiment was aimed at confirming that silages made of two very similar hybrids could have different in vivo digestibility, primarily amylase-treated neutral detergent fibre digestibility (aNDFD), which could strongly influence the result of the calculation of energy value of fodder. Both the stay-green whole-plant types were grown at the same locality during two years and harvested at the same days at two-thirds milk line maturity. In the two subsequent years, silages without preservatives were made of both hybrids tested. All silages were fermented for 90 days. The in vivo digestibility of silages was measured in digestion trials with six sheep. All silages had good fermentation quality, and no differences in that regard were found between hybrids or years (P > 0.05). Hybrid had stronger effect than year on all indicators of chemical composition and digestibility of nutrients other than dry matter (DM). Hybrid significantly affected all indicators measuring chemical composition and digestibility of nutrients other than DM (P = 0.18). The aNDFD was closely correlated with all other measures of nutrients digestibility (P < 0.01). The results confirm the importance of breeding hybrids and analyzing silages for aNDFD.

Rumen simulating techniques (Rusitec) were used to determine the impact of diets containing milled oilseeds on the fermentation parameters and amount of fatty acids (FA) in the effluent. High-forage diets containing no oilseeds (control diet (CD)) or 10% oilseed meal from rapeseed (RS), sunflower seed (SS), or flaxseed (FS) were used on a dry matter (DM) basis. No differences in DM digestibility were observed between the diets. Inclusion of SS and FS significantly reduced the pH values of the ruminal fluid, and a significant decline in the ammonia nitrogen (NH 3 -N) (mg/d) production in effluent was observed in the vessels with SS. Generally, oilseeds in these diets significantly reduced the amount of total fermentation gases (L/d); however, only a tendency toward methane (CH 4 , %) decrease was detected. The addition of oilseeds also significantly diminished the amount of total volatile fatty acids (VFA) produced (mmol/d). Significant reductions in the amounts of saturated FA in the vessels with RS and FS were observed compared with the CD and a significantly higher amount of monounsaturated fatty acids (MUFA) was noted in the vessels with RS. An increased amount of polyunsaturated fatty acids (PUFA), compared with the CD, was statistically significant only in the vessels with FS.