Effects of fermented apple pomace based TMR on the performance and gastrointestinal bacteria community of beef cattle

Apple pomace is a by-product of juice industry which rich in polysaccharides and vitamins. But it is also characterized with high-water content that is hard to preserve, which severely restricts its application in ruminant husbandry. In this experiment, apple pomace was mixed into the diet to prepare a fermented total mixed diet (FTMR) utilizing ferulic esterase-producing Lactobacillus plantarum A1 to promote fermentation, and to study the effects of FRMR on growth performance, blood parameters and gastrointestinal microorganisms of beef cattle. The experiment was designed as a one-way completely randomized trial. A total of 50 Simmental steers with similar body weight (630.0 ± 5.5) kg were randomly assigned to the regular TMR dietary treatment (CON) or FTMR treatment. The total period of the whole experiment was 60 d, including a pre-feeding period of 15 d. The results showed that FTMR treatment significantly increased average daily gain (P < 0.01), apparent digestibility of crude protein (P < 0.01), but decreased count of white blood cells (P = 0.039), hemoglobin content (P < 0.01) and platelet distribution width (P = 0.039). The concentrations of total volatile fatty acids (P = 0.026), acetate (P = 0.023) and propionate (P = 0.039) in rumen were increased. The FTMR treatment significantly increased the relative abundance of Fibrobacterota, Fibrobacter, Prevotella and Lachnospira in rumen (P < 0.05) compared to the CON treatment. At the genus level, the abundances of Clostridium_sensu_stricto_1 and Parabacteroides in cecum was significantly higher in the FTMR treatment than those in the CON treatment (P < 0.05). In conclusion, the fermented total mixed diet supplemented with apple residue could improve the performance and rumen fermentation parameters, as well as increase beneficial bacteria in gastrointestinal tract of steers. Therefore, fermented TMR technology can efficiently utilize the feedstuffs that were difficult to preserve, and it is important for the development of unconventional feed resources.