Forage substitution in a grain-based diet affects pH and glycogen content of semimembranosus and semitendinosus rabbit muscles.

The effects of nutritional level on glycogen content and pH of semimembranosus (SM) and semitendinosus (ST) rabbit muscles were investigated. Rabbits weaned at 30 d of age were fed one of three diets in which grain had been replaced with 0, 15, and 45% coast cross bermudagrass (Cynodon dactylon Pers.). Muscles were sampled at .5, 3.5, 6.5, and 24 h after slaughter. Results showed that these isoenergetic and isoproteic diets did not affect the total number of days required for rabbits to attain 2 kg of live weight. The SM muscle of animals fed the 0% forage diet exhibited higher glycogen content than the SM muscle of rabbits maintained on 15 and 45% forage diets at all sampling times. At .5 h after slaughter, the glycogen content of SM from the 15 and 45% dietary groups was decreased by 65 and 79%, respectively, in relation to the 0% dietary group. For ST, glycogen content was higher only at the first sampling time for the 0% forage diet (diet with no addition of bermudagrass) when compared with animals maintained on diets with forage. For SM and ST, significant differences in muscle pH among dietary groups was observed at 6.5 and 24 h after slaughter, and rabbits maintained on a 45% forage diet showed a higher ultimate pH than animals fed 0 or 15% forage diets. These results demonstrate that grain replacement with forage in diets for rabbits causes a decrease in glycogen content in two types of muscles and results in higher ultimate pH, which may affect the shelf-life quality of the meat.