The effects of tryptophan and pyridoxine supplied orally to nursing piglets on weight loss and social behavior after weaning

This study evaluated the effect of oral supplementation with tryptophan (Trp) and pyridoxine (Pyr) on the growth performance and social behavior of suckling piglets before and after weaning. At day 14, six suckling piglets per sow were distributed into three treatments and allotted in a randomized block design, with eight replicates and two piglets per experimental unit. Treatments consisted of a Control - oral supplementation with L-alanine (1.70 g), D-glucose (1.74 g) and distilled water (3.44 mL); Trp - oral supplementation with Trp (3.5 g/d) and distilled water; and Trp + Pyr - oral supplementation with Trp (3.5 g/d) + Pyr (0.0095 g/d) and distilled water. Each treatment was supplied orally five times per day (2.5 mL each treatment), from 14 to 21 days old. Piglets were monitored continuously in the nursing phase for 24 h at 21, 28 and 33 days of age to assess the behavior (standing, lying, eating, socializing, sitting and drinking). Piglets receiving oral Trp + Pyr showed a decreased weight loss on the first day after weaning (P = 0.03). Performance was not affected (P > 0.05) by treatments in each studied period, such as in overall period (21 to 34 days) after weaning. Piglets receiving Trp supplementation visited the feeders more frequently from days 21 to 22 (P < 0.01) and from days 28 to 29 (P < 0.02), as well as in the overall period (P < 0.01). It is concluded that high doses of tryptophan with or without high doses of pyridoxine, supplied orally to nursing piglets, reduced the weight loss on the first day after weaning and increased the frequency of visits to the drinkers on the first day after weaning and also to the feeders, mainly from weaning until 7 days after.