Influence of carbohydrates to protein ratio of concentrate feedstuffs on in vitro gas production kinetics and methanogenesis Srinivas Bandla, Swain N. Division of Animal Nutrition, Central Sheep and Wool Research Institute, Avikanagar, 304501, India. E-mail address: bandla_srinivas@rediffmail.com. Abstract Among different type of concentrate feedstuffs (CFS) 9 grains, 4 cakes and 3 by-products were taken to characterize in vitro gas and methane production. These ingredients were grouped in to 2 broad categories such as narrow (1:1 or 2:1) and wider (7:1) ratio of carbohydrate (CHO) to crude protein (CP). Ether extract (EE) was taken as covariate. Cumulative gas production (CGP) was significantly rapid till 12 h of incubation in narrow CHO: CP ratio CFS. CGP in wider CHO: CP ratio CFS was 65 (P< 0.001), 37 (P< 0.001) and 21 (P< 0.001) % lesser than other category at 4, 8, 12 h of incubation however, difference was reduced to 6 and 3% at 18 and 24 h of incubation. Difference in CGP at initial hours of incubation was greater for cereals and pulses rather than by-products. First order gas production kinetics indicated significantly difference in rate constant of fermentation and t-half time between CFS having narrow and broader ratio of CHO: CP. Lag time and total gas production had significant correlation (P< 0.001) with methane proportion with adjusted R2 value of 0.61 (P< 0.001). CP and EE were negatively correlated with methane proportion in total gas but, only r-value of the latter was significant (P< 0.05). TC was positively related yet its r-value was not significant. CHO however, was positively (r = 0.79; P< 0.001) and, CP (r = −0.47, P< 0.05) or EE (r = −0.63, P< 0.01) were negatively related with total gas production. Study concluded that the gas production pattern of CFS indicated that the narrow CHO: CP ratio was important for initial rapid fermentation. Although extent of fermentation was similar with CFS with wider CHO: CP ratio, their initial fermentation was. Rate constant and t-half of gas production was dependent of characteristics of feedstuffs. Fat content had significant negative affect on methane production. This information can be useful in formulating environ-friendly concentrate supplements using CFS having narrow CHO: CP ratio to balance roughage diets having high rumen retention time. Top Key words Concentrate feedstuffs, Kinetics, Macronutrients, Methane, Rate constant. Top |