Effect of Nitrate, Two Oils and Their Combinations Added To Two Different Forage: Concentrate Ratios On Some Rumen Parameters and Protozoa Population.

Abstract This study aimed to determine the effects of nitrate, and two oils (O) (soybean and hazelnut oils) alone or in combination, on in vitro methane (CH4) production, volatile fatty acid (VFA) and ammonia (NH3) concentrations, pH, and protozoa population. For that, 2 x 2 x 3 factorial design with 2 two different forage:concentrate (F:C) ratios (40F:60C, and 60F:40C), 2 sources of nitrogen (sodium nitrate (NO−3: 45.94 g/kg DM) or urea (16.45 g/kg DM for control group) and 2 oils (hazelnut oil (HO: 36.58 g/kg DM) or soybean oil (SO: 36.58 g/kg DM)). For every forage: concentrate (F:C) ratio, six (6) treatment groups were formulated: F:C + Urea, F:C + NO−3, F:C + Urea + HO, F:C + Urea + SO, F:C + NO−3 + HO, F:C + NO−3 + SO. For every F:C ratio while NO−3 (p<0.01), oils (p<0.01), and NO−3 + oils (SO, HO) (p<0.01) decreased CH4 content, protozoa population, ammonia (NH3) concentration, acetic acid, total VFA, acetic acid: propionic acid ratio and pH, they increased butyric acid and propionic acid concentrations. Furthermore, CH4 production (12.44 vs 9.09 ml), ammonia (8.23 vs 7.37 mmol/l), propionic acid (19.14 vs 17.93 mmol/l), butyric acid (15.50 vs 14.50 mmol/l), total VFA (86.46 vs 85.66 mmol/l), protozoa population (32.16 vs 26.96 x104 ml.) were high in early lactation period. In both lactation periods, SO, and NO−3 + SO decreased acetic acid concentration, protozoa population, and thus CH4 production.