Effects of replacing commercial material with apple pomace on the fermentation quality of total mixed ration silage and its digestibility, nitrogen balance and rumen fermentation in wethers

In this study, we evaluated the fermentation quality, digestibility and rumen fermentation of total mixed ration silage (TMRS) prepared with varying proportions of apple pomace, using four wethers in a 4 x 4 Latin square study design. A control diet was prepared using corn, wheat bran, timothy hay, alfalfa hay and a vitamin-mineral supplement. In the experimental treatments, apple pomace supplemented with soybean meal was used to replace corn and wheat bran at levels of 5%, 10% and 20% on a dry matter (DM) basis; treatment levels are indicated by these replacement levels. The moisture content of all diets was adjusted to 550 g/kg and the diets were then ensiled for 60 days. All diets were well fermented, with low pH and ammonia nitrogen (N) content. In treatments including apple pomace, lactic acid content decreased as acetic acid increased compared with the control (p < .05). Ethanol was generated in the 5%, 10% and 20% treatments. Following the addition of apple pomace, ammonia N content increased, and was highest in the 5% treatment (p < .05). N retention and digestibility of DM, organic matter, crude protein and ether extract decreased significantly (p < .05) in the 10% and 20% treatments. The rumen molar proportion of acetic acid increased, but those of propionic acid and ammonia N content decreased as the proportion of apple pomace in the diets increased (p < .05). The results of this study suggest that the proportion of apple pomace in TMRS should not exceed that of the 5% TMRS treatment, which was 44 g/kg of diet DM.