Abstract Weaning and transport stress has the potential to impair piglet performance, especially during summer months. L-glutamate (GLU) supports pig health and productivity, but its optimal delivery and dosage remain unclear. This study evaluated the effects of increasing liquid GLU provided 1-week pre- to 1-week post-weaning on piglet performance following weaning and summer transport. We hypothesized that greater GLU provision would enhance piglet performance following weaning and summer transport. In period 1 (P1), 24 litters (N = 230 piglets; Duroc x Landrace x Yorkshire) received a liquid control (CON), 0.5 (GLU1), 2.0 (GLU2), or 3.0 g/piglet (GLU3) GLU supplement (45 mL/piglet/day) via a pen waterer for 7 d prior to weaning, and daily refusals were recorded (n = 6 litters/treatment). Litters were assigned to treatments based on birth weight and sow parity. At weaning, piglets (d 19.7 ± 1.8 of age; 6.2 ± 0.4 kg) were transported for 9 h during the summer with trailer temperatures of 33.5 ± 2.7 °C. Following transport, pigs were placed into pens balanced by sex, litter of origin and blocked by body weight (BW). In period 2 (P2), pens (n = 10 pens/treatment; 5 pigs/pen) were assigned to one of four treatments, delivered ad libitum via a water medicator for 7 d post-weaning and transport, matching their pre-weaning assignment. Average daily water intake (ADWI) was assessed daily per pen using a water meter. Pigs were provided ad libitum access to a standard corn-soybean meal-based diet. Body weight was recorded on d 1, 7, 14 of life; at weaning; immediately post-transport; and every 7 d thereafter through d 35 post-weaning to calculate average daily gain (ADG). In period 3 (P3), all pigs were withdrawn from treatment and given plain water from d 7 to 35 post-weaning. Feed refusals were recorded on d 7, 14, 21, 28, and 35 to calculate average daily feed intake (ADFI). Litter was the experimental unit pre-weaning and pen was the experimental unit post-weaning. Weaning BW was greater for CON than GLU3 pigs (P = 0.04; +0.93 kg), with no differences among other treatments. During P2, ADG was higher for GLU3 pigs compared to all other treatments (P 0.01; +7.6%), and ADFI was greater for GLU3 than CON and GLU1 pigs (P = 0.02; +34.5%), but similar to GLU2. At the end of P2, BW was lower (P = 0.02; −7.4%) in GLU2 and GLU3 pigs compared with CON pigs. In the P3 period, a treatment by day interaction was detected for ADG (P = 0.02) and ADWI (P = 0.01), but means separation revealed no differences. In conclusion, increasing pre-weaning GLU supplementation slightly reduced weaning weight but increased post-weaning growth rate following weaning and summer transport.
Sullivan et al. (Wed,) studied this question.