Effect of Dietary Electrolyte Balance in Low‐Protein Diet on Intestinal Barrier, Mitochondrial Function and Carcass Quality of Growing Pigs

In a low-protein diet, dietary electrolyte balance may be disrupted due to the reduction in the amount of soybean meal used and supplementation with lysine hydrochloride. The objective of this experiment was to evaluate the effects of dEB on intestinal barrier, mitochondrial function and carcass quality of growing pigs fed a low-protein diet. A total of 144 pigs (initial body weight 25.45 ± 0.36kg) were allotted to the control group with a crude protein (CP) level of 15.7% (CON, dEB 173 mEq/kg) or one of three low-protein groups (CP 14%) with different dEB values: LE (dEB 120 mEq/kg), ME (dEB 180 mEq/kg), and HE (dEB 240 mEq/kg) groups. The results showed that compared with the CON group, the average daily weight gain of pigs in the LE and HE groups was decreased by 4.7% and 4.3% respectively (p < 0.05), while the ratio of weight gain to feed intake was reduced by 6.7% and 4.4% respectively (p < 0.05), while the growth performance of the ME group was similar to that of the CON group (p > 0.05). Compared to the CON groups, intestinal villi, transepithelial electrical resistance and expression of tight junction proteins (ZO-1, Occludin and Claudin-1) were significantly decreased (p < 0.05) in the LE and HE group. For mitochondrial function, compared with the ME and CON groups, the LE group decreased (p < 0.05) jejunal mitochondrial membrane potential and ATP content, and activities of mitochondrial complexes I, II, and III. As compared with the LE group, the redness of the longissimus dorsi muscle was increased by 5.7% and 6.6% respectively (p < 0.05) and the drip loss was decreased by 8.3% and 9.4% respectively (p < 0.05) in the ME and HE group. The meat quality of the CON group was similar to that of the ME and HE groups (p > 0.05). In summary, dEB could significantly affect intestinal barrier, mitochondrial function and carcass quality, and the proper dEB in low-protein diet was 180 mEq/kg in growing pigs.