The interaction between lactofeed level and soya-bean meal on growth performance of weanling pigs

A 3 X 2 factorial experiment was conducted to investigate the interaction between lactofeed 70 (LF70) (860 g/kg whey permeate, 140 g/kg soya-bean meal, Volac International, UK) levels and soya-bean meal inclusion (SBM) (90 and 225 g/kg) from day 0 to day 25 after weaning (starter period) on growth performance and diet digestibility. A common diet was offered from day 25 to day 38. Dietary treatments were established by substituting LF70 for extruded wheat and soya-bean meal for potato protein (PP) and soya protein concentrate (SPC). Digestible energy and amino acids were maintained by adjusting soya oil and synthetic amino acids. A total of 252 pigs (7.7 kg and 28 +/- 2 days of age) were allotted randomly to six treatments containing (1) 0 LF70 with 40 g/kg PP and 40 g/kg SPC and 90 g/kg SBM ( 2) 0 LF70 with 225 g/ kg SBM ( 3) 175 g/kg LF70 with 40 g/kg PP and 40 g/ kg SPC and 90 g/ kg SBM ( 4) 175 g/kg LF70 with 225 g/kg SBM ( 5) 350 g/kg LF70 with 40 g/kg PP, 40 g/kg SPC and 90 g/kg SBM and ( 6) 350 g/kg LF70 with 225 g/kg SBM. There was an increase in average daily gain (ADG) (0.182 v. 0.292 v. 0.318 kg, s.e. 0.0089; P < 0.001) and food intake (0.413 v. 0.472 v. 0.489 kg, s.e. 0.0139; P < 0.01) and an improvement in food conversion ratio (FCR) (2.31 v. 1.63 v. 1.55 kg, s.e. 0.037; P < 0.001) as the level of LF70 increased during the starter period. From day 25 to day 38, the pigs given the starter diets containing no LF70 had an improved ADG (P < 0.05) and FCR (P < 0.001) compared with the pigs given 175 and 350 g/ kg LF70. The pigs offered diets containing 350 g/ kg lactofeed had a significantly higher N digestibility (P < 0.05) than the pigs offered diets containing no lactofeed. There was a significant interaction (P < 0.001) between LF70 and SBM in the apparent digestibility of gross energy (GED). Pigs given higher SBM diets had a higher GED at the 350 g/kg LF70 inclusion than pigs given PP + SPC diets. However, there was no difference in GED at the 0 and 175 g/kg LF70 inclusion. In conclusion, the inclusion of LF70 increased ADG, food intake and apparent N digestibility and improved FCR.