The interaction between dietary crude protein and amino acid levels in weaner pigs in an antibiotic-free environment with or without Bacillus amyloliquefaciens supplementation

The interaction between dietary crude protein and amino acid levels in weaner pigs in an antibiotic-free environment with or without Bacillus amyloliquefaciens supplementation Natasha van Niekerk High crude protein (CP) diets cause a myriad of digestive problems in weaner pigs due to incomplete digestion. This is caused by an immature digestive system at weaning. These problems present themselves as increased diarrhoea and reduced growth performance in weaner pigs. Many of the negative consequences could in the past be rectified through the use of antibiotic growth promoters (AGPs). However, AGPs are becoming more closely scrutinised by the general public and government officials and it is therefore imperative that alternative feed additives and dietary strategies are explored so that weaner pig performance is not impaired in the face of AGP bans. The effect of a 3% dietary CP reduction and 10% elevation of lysine, methionine, threonine, tryptophan and valine and/or Bacillus amyloliquefaciens was investigated in weaner pigs of 28 days old. The experiment was performed on 162 pigs with six dietary treatments; comprising of two CP levels (21% or 18% in the pre-starter diets and 18% or 15% in the starter diets), two amino acid levels (recommended amino acid level or elevated by 10%) and with or without the supplementation of a probiotic additive (Bacillus amyloliquefaciens). The total trial period was 42 days, divided into a pre-starter phase and starter phase, both of 21 days each. Growth performance and faecal score was measured for the entire trial period. In addition, after 21 days of the trial, 54 pigs were humanely euthanised to determine the gut health effects of the dietary treatments. Crude protein level resulted in significant effects on body weight (BW), average daily gain (ADG) and gain to feed ratio (G: F) in both the pre-starter and starter phase. The pigs consuming the HP diets had increased (p <0.05) BW at day 7, 14, 21, 28 and 35, and higher ADG (p <0.01) between days 7-14 and 7-21. In addition, high CP diets resulted in increased (p