Mannose rich fraction of Saccharomyces cerevisiae promotes growth and enhances carcass yield in commercially housed grower–finisher pigs

An 80 day study was conducted to evaluate the growth promoting effects of a unique mannose rich fraction (MRF) derived from yeast cell walls of Saccharomyces cerevisiae, relative to copper and tylosin in commercially housed grower and finisher pigs. 1008 male grower pigs (29.7 ± 1.99 kg live weight) were randomly allocated to four treatment groups of 252 pigs. There were 12 replicates for growth rates (21 pigs per pen) and 6 replicates for feed intake and FCR (42 pigs per feeder). The dietary treatments consisted of a control (CON, containing no growth promoting feed additives), copper (COP, containing 200 ppm of copper as copper sulphate in both grower and finisher pigs), MRF (containing 400 ppm and 200 ppm of Actigen™ (Alltech Biotechnology, Nicholasville, KY) in grower and finisher diets respectively), and tylosin (TYL, containing 40 g and 20 g of tylosin in grower and finisher diets respectively). Growth performance and mortality were monitored over the grower (d 0–38) and finisher (d 39–80) periods. Slaughter characteristics (carcass weight and backfat thickness at the P2 position) were recorded at d 80. Mannose rich fraction pigs grew faster (P<0.01) than CON or COP pigs during the grower phase. Mannose rich fraction and TYL pigs also tended to (P=0.08) have better FCR during the grower phase than those on the CON and COP treatments. No significant treatment effects were observed for growth performance during the finisher phase or over the entire study (d 0–80). However, MRF pigs had a significantly higher (P<0.01) dressing percentage and heavier carcass weight than pig on all other treatments. There was no influence of growth promoting feed additives on backfat thickness. Overall, MRF was as effective as tylosin and more effective than copper as a growth promoter in grower pigs. Mannose rich fraction inclusion was able to enhance the yield of saleable pork, and was the most effective growth promoting option tested.