This study aimed to evaluate the effect of exogenous enzymes (ExE) on feeding behaviour, feed intake, nutrient digestibility and rumen disappearance rate of Holstein cows, as well as methane production from faeces of these cows by means of anaerobic digestion. Five cannulated Holstein cows were distributed in a 5 × 5 Latin square design (5 periods of 21 days each) and received five treatments which differed in inclusion of different ExE in the diet (control: diet without enzymes; amylase: basal diet with 7.5 g of amylase/cow/day; xylanase: basal diet with 15 g of xylanase/cow/day; cellulase + protease: basal diet with 7.5 g cellulase + protease/cow/day; and pool: basal diet with 30 g enzyme mixture (all enzymes added at the same dose of individual treatments). Therefore, feeding behaviour, dry matter intake (DMI), nutrient digestibility and rumen disappearance rate were evaluated. Representative pools of faeces from each cow were collected in each period to perform anaerobic digestion. Afterwards, 25 experimental batch-type biodigesters were filled with faece substrates and were subsequently arranged in a completely randomised design of 5 treatments with 5 replicates. Then, evaluations of total gas, methane production, total solid (TS) and volatile solid (VS) removal efficiency were performed. No effect of ExE was observed (P>0.05) on feeding behaviour (number of daily meals; total daily time spent eating, ruminating or masticating), DMI, nutrient digestibility (although enzyme pool and cellulase + protease tended to increase crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility) or on rumen disappearance rate. No effect of ExE was observed on total gas and methane production or on the efficiency of removal of TS and VS from faeces. Exogenous enzymes did not increase efficiency of nutrient utilisation by the animals and, accordingly, did not affect the potential of methane emission from faeces of Holstein cows by means of anaerobic digestion. تفاصيل المقالة

This study aimed to evaluate the effect of different exogenous enzymes or their combination on nutrient digestibility and ruminal fermentation of Holstein cows. Five ruminally cannulated adult Holstein cows were distributed in a 5 × 5 Latin square design and received the same basal diet consisting of 30% of corn silage and 70% of concentrate but with inclusion of different exogenous enzymes comprising five treatments (control: diet without enzymes; amylase: basal diet with 7.5 g of amylase/cow/day; xylanase: basal diet with 15 g of xylanase/cow/day; cellulase + protease: basal diet with 7.5 g cellulase + protease/cow/day; and enzyme pool: basal diet with 30 g enzyme mixture (7.5 g of amylase, 15 g of xylanase and 7.5 g of cellulase + protease)/cow/day). Accordingly, the experiment was conducted in five periods of 23 days each. Therefore, data were collected to evaluate nutrient digestibility and ruminal fermentation parameters. The different exogenous enzymes or their combination (enzyme pool) did not affect (P>0.05) nutrient digestibility, ruminal pH, protozoa population, ammonia nitrogen and methane concentration and production. The enzyme combination and cellulase + protease increased (P<0.05) the concentration and production of acetate and propionate as well as total short-chain fatty acids, but did not significantly affect the relative energy loss of methane concering the other rumen fermentation products (acetate, propionate, and butyrate). Therefore, the dietary supplementation of different exogenous enzymes or their combination in Holstein cows did not improve feed value, but the enzyme combination has shown a tendency to reduce the relative energy loss of methane. تفاصيل المقالة

This study aimed to evaluate the effect of Acacia mearnsii tannins and monensin combination on rumen fermentation parameters and feed energy partitioning of Nellore cows. In a 2 × 4 factorial arrangement, 8 cannulated Nellore cows were distributed in 2 contemporary 4 × 4 latin square design and received 8 diets that differed in the level of tannin inclusion (0.00, 0.75, 1.50 and 2.25% of feed dry matter (DM)) and presence of monensin. Monensin was daily administered to each cow in one square (about 32 mg/kg DM). Accordingly, the experiment was conducted in 4 periods of 28 days each. Therefore, daily dry matter intake (DMI), gross energy intake (GEI), rumen solid mass, neutral detergent fibre (NDF) degradability, rumen pH, rumen fermentation products and rumen protozoa were measured and the feed energy partitioning was evaluated. The only interaction (antagonistic) observed between monensin and tannins was on the minimum rumen pH (P=0.0173). Monensin reduced acetate:propionate production ratio in 28.80% (P=0.0007). Tannins linearly reduced DMI, GEI and NDF degradability, but linearly increased rumen solid mass (P<0.05). Tannins had a quadratic effect on the time (min/day) the rumen pH was below 5.8 and 6.0, as well as the pH area (h.pH/day) below 5.8, 6.0 and 6.2. Tannins had neither effect on rumen ammonia nor on protozoa count (P>0.05). Tannins linearly reduced CH4, acetate, butyrate and total short chain fatty acids (SCFA) production as well as the gross energy release in form of CH4, but linearly reduced the energy release in intestine and linearly increased feed energy loss in faeces. Monensin and tannins had independent effects on rumen fermentation parameters, as well as on feed energy partitioning, therefore, no synergy was observed. The use of A. mearnsii tannins up to 2.25% of feed DM reduced CH4 production (up to 34.7%), but did not improve feed energy efficiency. تفاصيل المقالة