Effects of sweetener neotame on diet preference, performance and hematological and biochemical parameters of weaned piglets

• Weaned pigs showed preference and higher intake for a diet supplemented 30 mg/kg neotame than control diet.
• ADFI and ADG were optimized between weaning and 35 days on diets supplemented with 20.7 or 21.7 mg/kg neotame, respectively.
• Neotame levels up to 500 mg/kg diet had no damage to weaned pigs.

Three experiments were conducted to evaluate the effects of a sweetener, neotame (N-[N-(3,3-dimethylbutyl)-l-α-aspartyl]-l-phenylalanine 1-methyl ester) on diet preference, performance and hematological and biochemical parameters of weaned piglets. In experiment 1, 48 weaned piglets (Duroc × Landrace × Large White), with an initial body weight (BW) of 9.05 ± 0.04 kg, were used in a diet preference study. Pigs were assigned to 8 pens with 6 pigs per pen. Each pen was equipped with two feeders, containing a maize-soybean meal based diet or a similar diet supplemented with 30 mg/kg neotame. The experiment lasted for 15 days, including a 5-d adaptation period and a 10-d experiment period. The diet supplemented with 30 mg/kg neotame was preferred (P < 0.05) by the pigs during d 7, d 10 and the entire experimental period (d 1–10). In experiment 2, 216 weaned piglets, with an initial BW of 7.35 ± 0.06 kg, blocked by gender and BW, were allocated to 1 of 6 treatments with 6 pens per treatment and 6 pigs per pen. Weaned piglets were fed the basal diet or similar diets supplemented with 10, 20, 30, 40 or 50 mg/kg neotame. The experiment lasted for 35 days. Average daily feed intake (ADFI) was improved linearly (P < 0.05) with increasing dietary neotame level during phase I (d 1–22) and the entire experimental period (d 1–35). A quadratic (P < 0.05) effect of neotame was observed on average daily gain (ADG) and ADFI during phase I (d 1–22), phase II (d 23–35) and the entire experimental period (d 1–35). The optimal concentrations of dietary neotame to maximize ADG and ADFI during entire experimental period using a fitted quadratic plot model were 21.7 and 20.7 mg/kg, respectively. Experiment 3 was conducted with 108 weaned piglets averaging an initial BW of 7.34 ± 0.08 kg to evaluate the effects of neotame on hematological and biochemical parameters of weaned piglets. Pigs were divided into 3 treatments with 6 pens per treatment and 6 pigs per pen, and fed the basal diet or similar diets supplemented with 50 or 500 mg/kg neotame. There was no difference (P > 0.05) in blood parameters, organ index and morphology among the three treatments. In conclusion, the optimal concentrations of dietary neotame for maximum ADFI and ADG was ranged from 18.0 to 20.4 mg/kg during phase I (d 1–22), 22.0 to 22.9 mg/kg during phase II (d 23–35) and 20.7 to 21.7 mg/kg during entire experimental period (d 1–35), and no adverse effects on indicators of health were observed in pigs offered diets with neotame levels up to 500 mg/kg.