Effects of different levels of fibre and benzoic acid on growth performance, nutrient digestibility, reduction of noxious gases, serum metabolites and meat quality in finishing pigs

A total of 96 finishing pigs [(Landrace x Yorkshire) x Duroc; 56.67 +/- 2.69 kg] were used in a 10-week trial to evaluate the growth performance, nutrient digestibility, reduction of noxious gases, serum metabolites and meat quality. Pigs were allotted to dietary treatments based on body weight in a 2 x 2 factorial experiment, with the respective factors being fibre (low vs. high; 13.5, 16% non-starch polysaccharide, respectively) and benzoic acid (BA; 0, 0.5% BA) with six replicate pens consisting of four pigs per pen. Wheat bran and sugar beet pulp were used for dietary fibre sources with the level of 5%, respectively in the high fibre (HF) diet. All of the diets were mash type and formulated to contain net energy 9.80 MJ/kg and 16% crude protein. Throughout the experimental period, pigs fed HF diet had lower average daily gain than those fed low fibre (LF) diet (P = 0.02). However, fibre treatment did not affect the average daily feed intake. During the first five weeks, the apparent total tract digestibility (ATTD) of dry matter was higher in the pigs fed LF diet (P < 0.05). The ATTD of nitrogen and gross energy was increased when pigs fed LF included BA (P < 0.01 and P < 0.05, respectively). HF treatment showed the reduction of noxious gases such as NH3, RSH and H2S detected at d 35 and 70 of this experiment (P < 0.05). Total cholesterol and low-density lipoprotein cholesterol were lower in the blood of pigs fed HF diet (P < 0.05). In the current study, marbling score was improved in the HF group compared to the LF group (P < 0.05). Finally, HF diet had an adverse effect on growth performance but a beneficial effect on reduction of noxious gas and cholesterol and meat quality.