The objective of the study was to determine the effect of adding buffering agents to a total mixed ration (TMR) on the pH and on the VFA, lactic acid and NH3-N content of rumen fluid. The experiment was carried out with three nonproductive cows fitted with permanent rumen fistulas in a 3×3 Latin square design with two stages differing in the amount of added buffer (50 g/day in stage I or 100 g/day in stage II). The control diet (C) contained no buffering agent. The AB experimental diet was supplemented with Acid Buf (Noack Polen Ltd.) containing calcium carbonate, major and trace elements, and the AS experimental diet was supplemented with our own produced artificial saliva powder containing a mixture of chemical compounds (NaHCO3, KCl, CaCl2, Na2HO4·12H2O, NaCl, MgSO4·7H2O) in the appropriate proportions (McDougall, 1948), combined with wheat bran at a 1:1 ratio. The preparations were added to the concentrate mixture in TMR which contained (% DM): maize silage, 29.9; wilted grass silage, 17.4; ensiled brewers’ grains, 2.4; barley straw, 10.3; and concentrate mixture, 40.0. Samples of rumen fluid collected before feeding (0 h) and after feeding (2, 4, 6 and 8 h) were analysed for pH, and the samples collected 4 h postprandial were analysed for VFA, lactic acid and NH3-N. The artificial saliva added at 100 g/day to the mixture of chemical compounds (without a carrier) contributed to a significant (P≤0.01) increase in rumen fluid pH at 4 h compared to cows receiving diets C and AB. In both stages of the experiment, cows receiving the buffering agents tended to achieve higher pH values in the other hours of the test compared to group C. In the collected samples of rumen fluid, no significant (P>0.05) differences were observed among the cows in VFA and total VFA, in C2/C3 and C3/C4 acid ratios, and in NH3-N content. Neither did the type and amount of buffers had a significant effect on the percentage ratios of selected fatty acids (acetic, propionic and butyric) in total VFA. No presence of lactic acid was detected in the analysed samples of rumen fluid. It can be stated that when the total mixed ration is properly balanced, the type and amount of buffers have no significant effect on changes in the rumen fermentation activity of cows.
The aim of the study was to evaluate the immune effects of genetically modified (GM), insect resistant corn (MON810) expressing toxin protein of Bacillus thuringiensis, and glyphosate-tolerant soybean meal (Roundup Ready MON-40-30-2), which are used as the feed mixture components in domestic animals. The study was conducted on 60 pigs (36 fatteners and 24 sows), 20 calves, 40 broilers, and 40 laying hens. Each species was divided into four basic nutritional groups: group I (control) - conventional feed, group II - feed consisted of GM soybean meal and non-modified corn, group III - non-modified soybean meal and GM corn, group IV - GM soybean meal and GM corn. Moreover, in the experiment on fatteners two additional groups were formed: group V - animals fed both conventional soybean meal and bruised grain, and group VI - GM soybean meal and conventional bruised grain. The results of study did not reveal any significant effect of feed mixtures containing GM components on the immune response in all animals regardless of their species and technological producing groups.
Histopathological examination of liver, kidney, spleen, pancreas, duodenum, jejunum, skeletal muscle, and bursa of Fabricius samples, collected from broiler chickens, laying hens, fattening pigs, and calves fed genetically modified corn MON 810 and soybean meal MON-40-3-2 (Roundup Ready, RR), was performed The examination showed no significant differences between the control animals fed diets containing no genetically modified feeds and animals fed genetically modified feeds. In some cases, congestion of parenchyma and focal lymphoid cell infiltrations were observed in all dietary groups, including controls, and therefore, it was assumed that the lesions were not associated with the feeding transgenic feeds.