The responses of light- and heavy-for-age pigs at weaning to dietary spray-dried porcine plasma

Light-for-age pigs are generally regarded as the most disadvantaged group at weaning for subsequent post-weaning performance and survival. The main objective of this study was to demonstrate that weaner diets containing spray-dried porcine plasma (SDPP) could assist light-for-age pigs to perform better than their heavier counterparts after weaning. A total of 96 pigs weaned at 21 days (d) were used in a 2 × 2 factorially designed experiment with the respective factors being live weight (LW) (light- 4.9 ± 0.67 kg LW or heavy- 6.9 ± 0.73 kg LW for-age pigs) and SDPP supplementation (0 g/kg vs. 50 g/kg and 25 g/kg, for phase I and II respectively). The concentration of immunoglobulins (Ig) G, M and A in the SDPP included in the diets was 108, 33 and 7 g/kg, respectively. Each treatment had 8 replicates (pens) with 3 pigs per pen. Phase I diets were fed for the first week and phase II diets for the following 2 weeks until the experiment ceased at 21 d after weaning. One pig per pen, randomly selected, was bled on d 7 and 14 to measure circulating levels of Ig, routine haematology indices and plasma urea nitrogen (PUN). The inclusion of SDPP in the diet improved (P < 0.001) performance of both light- and heavy-for-age pigs in the first week after weaning. These effects disappeared (P > 0.05) in the following 2 weeks and over the 3-week study, pigs supplemented with SDPP gained 20 g more per day (P = 0.09) than the control pigs. Haematology indices as well as Ig levels in plasma were similar between treatments except for IgG, which was highest (P < 0.05) in the heavy pigs not fed SDPP on d 14 of the experiment. Pigs fed SDPP diets had lower (P < 0.05) PUN levels than the pigs not fed SDPP on both d 7 and 14, indicating an increased efficiency of dietary protein utilisation as a result of SDPP supplementation. These results confirm the inclusion of SDPP in weaner pig diets to improve post-weaning performance but under the conditions of the experiment, failed to improve the production of light-for-age pigs compared to heavy-for-age pigs.