Effects of different starch structures on energy metabolism in pigs

Abstract Background Starch is a major component of carbohydrates and a major source of energy for monogastric animals. Starch is composed of amylose and amylopectin and has different physiological functions due to its different configuration and structure. It has been shown that the energy supply efficiency of amylose is lower than that of amylopectin. However, there are few studies on the effect of starch structure on the available energy of pigs. The purpose of this study was to measure the effect of different structures of starch in the diet on the net energy (NE) of pigs using a comparative slaughter method and to establish a prediction equation to estimate the NE of starch with different structures. A total of fifty-six barrows (initial body weight 10.18 ± 0.11kg) were used, and they were housed and fed individually. Pigs were divided into 7 treatments according to their weight, with 8 replicates for each treatment and 1 pig for each replicate. One of the treatments was randomly selected as the initial slaughter group (ISG). Pigs in the remaining groups were assigned to 6 dietary treatment and slaughtered at the conclusion of the experiment. The basic diet contains corn, soybean meal, without additional starch. The other five starch experimental groups were fed semi-pure diets with amylose/amylopectin ratios (AR) of 3.09, 1.47, 0.25, 0.15 and 0.12, respectively. The diets and water were provided ad libitum for 28 d. Results Results showed that compared with the high amylose (AM) groups (AR 3.09 and 1.47), the high amylopectin (AP) group (AR 0.15) significantly increased the final BW, average daily weight gain and average daily feed intake of pigs (quadratic, P < 0.01), but the F: G of the high amylose group was lower (quadratic, P < 0.05). In addition, the high amylopectin groups (AR 0.15 and 0.12) has higher (quadratic, P < 0.001) nutrient digestibility of dry matter, crude protein, gross energy and crude ash. Meanwhile, compared with other groups AR 0.15 group has a higher NE intake and energy retention (RE), while AR 3.09 group has the lowest NE intake and RE (linear, P < 0.05). The regressive equation for predicting with starch structures was established as RE = 1235.243-48.298AM/AP (r2=0.657, P = 0.05). Conclusions In conclusion, with the increase of dietary amylopectin content, NE intake and RE of pigs were increased, indicating that diets high in amylopectin were more conducive to promoting the growth of pigs in the late conservation period.