EFFECT OF PH ON SOYBEAN, SUNFLOWER AND RAPESEED OIL-CAKES FERMENTATION INTHE RUMENOF CATTLE IN VITRO

A. V. Hultyayeva, N. V. Golova, V. V. Vlizlo

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Institute of animal biology NAAS, st. Vasyl Stus, 38; Lviv, 79034, Ukraine

Requirement of metabolizable energy in the diets of high-yielding cows partially provided by fat supplements what can inhibit rumen metabolism. The influence of the addition of alkalizing mixture to the diet with high content of oil-cake on enzymatic processes in the rumen in vitro has been investigated. Oil-cakes contained 8,1–8,5 % of fat. Samples of rumen fluid were incubated for 8 hours withsoybean, sunflower seed or rapeseed oil-cake (25 ml rumen content filtrate + 75 ml of McDougall's buffer + 0.5 g of oil-cake) with the addition of alkalizing mixture containing 100 mg of sodium bicarbonate, 50 mg of carbonate calcium and 50 mg of magnesium carbonate.

Alkalizing mixture provided stabilization of rumen content pH, which at the end of incubation was in control samples 6.54–6.61 vs. 6.73–6.82 in the samples with added carbonates. Addition of the mixture of sodium bicarbonate and calcium and magnesium carbonates increased cellulolytic activity (p<0.001) and decreased amylolytic activity (p<0.05). Proteolytic bacteria are less sensitive to pH, but the proteolytic activity in the experimental incubates were slightly increased too. Incubation of rumen fluid with rapeseed cake resulted in lower total nitrogen and ammonia and lactate concentration compared to incubation with sunflower cake.

Adding to rumen fluid alkalizing carbonates mixture boosted the level of microbial protein in studies with all types of oil-cake (p<0.05–0.001). The concentration of lactate was decreased (p<0.01–0.001) due to rising pH. Alkalizing salts mixture increased the amount of total lipids and non-esterified fatty acids (p<0.05–0.01).

Keywords: COWS, OIL-CAKE, RUMEN CONTENT, ENZYMATIC ACTIVITY, NITROGEN, CARBOHYDRATES, LIPIDS, IN VITRO

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