Abstract
Reduction in dietary crude protein (CP) levels is recognized to potentially limit piglet growth. Synchronising blood amino acids and glucose peaks may improve the performance of piglets fed low-CP diets. This study aimed to evaluate the effects of a feeding plan with a low-CP diet and a reduced amylose to amylopectin (AM/AP) ratio, in the second phase, on performance, faecal microbiota and metabolites, and behaviour of nursery pigs. A total of 540 nursery pigs (28 ± 2 d) were fed either a medium-CP (CTR:16.6%, 180 pigs) or low-CP (LCP: 14.9%, 360 pigs) diet during phase 1 (d0 to 21), and then assigned to one of three phase 2 diets (d 21 to 63): medium-CP (CTR: 17.2%;180 pigs), low-CP with normal AM/AP ratio (LP: 15%; 0.17, 180 pigs), or low-CP with reduced AM/AP ratio (LPLA:15%; 0.08, 180 pigs). On d43 and 63, LP and LPLA pigs showed lower body weight than CTR pigs (P < 0.0001). No differences in feed to gain (F:G) were observed between CTR and LPLA from d43 to 63. The LPLA and LP diets had lower faecal alanine and proline concentrations than CTR at d48 (P < 0.05). The beta diversity of faecal microbiota was affected by the diet at d43 and d63 (P < 0.01); at d63, the LPLA diet was characterised by a higher abundance of Lactobacillus (P < 0.05) and Limosilactobacillus (P < 0.05). During the late phase of post-weaning, reducing the AM/AP ratio may help improve feed efficiency in pigs fed low-CP diets.