In vitro Gas and Methane Production of Horse Grass and Calopo at Different Forage to Concentrate Ratios in Rabbits

The in vitro gas production technique provides information about kinetics and fermentation characteristics of feedstuffs and diets, and it is a useful indicator of fecal microbial activity.

Aim: The aim of this study was to use the in vitro technique to study gas production kinetics and dry matter degradability of feed samples at different forage to concentrate (F:C) ratios using rabbit inoculum.

Materials and Methods: The treatments (T) were in a Completely Randomized Design with two forage sources namely Horse grass and Calopo mixed at 75:25 (T1) ratio and F:C ratios 75:25 (T2), 50:50 (T3), 25:75 (T4) and 100:0 (T5), respectively. Six New Zealand White rabbits (mean body weight [BW] = 0.86kg ±0.04) were used as inoculum donors.

Results: Crude protein of forages was 10.45 and 23.00 for Horse grass and Calopo respectively. The crude protein and crude fiber content of the supplementary concentrate was 17.01 and 6.00% respectively. Highest crude fiber (12.00) was also observed in Calopo. Diets 4 and 5 produced the highest (P<0.05) total gas (ml/200mgDM) and methane (ml/200mgDM) respectively, while in vitro degradability decreased with increasing supplementary concentrate (P<0.05). Sole forage diet resulted in highest dry matter degradability (6.90) and gas production (7.80).

Conclusion: It can be concluded that good quality forage, therefore, could reduce the need for concentrate supplementation.