Sylpro enhanced torula yeast is a high protein feed ingredient derived from forestry by-products, and results from digestibility experiments indicate that Sylpro yeast may be a valuable source of energy and digestible amino acids in diets fed to weanling pigs. As a consequence, it is believed that Sylpro yeast may be included in diets for weanling pigs at the expense of fish meal and other animal protein sources. Therefore, an experiment was conducted to test the hypothesis that increasing levels of Sylpro yeast improve growth performance and blood characteristics of weanling pigs.

Experimental design

One hundred sixty weanling pigs (initial BW: 6.11 ± 0.62 kg) were allotted to 1 of 4 diets during phases 1 and 2. There were 5 pigs per pen with 8 replicate pens per treatment. In phase 1, a control diet was formulated and contained 5% fish meal, 2.5% plasma, and no Sylpro yeast. Three additional diets were formulated to contain 10, 18, or 26% Sylpro yeast without inclusion of fish meal or plasma. In phase 2, the control diet contained 3% fish meal, no plasma and Sylpro yeast. Three additional diets were also formulated to contain 8, 14, or 20% Sylpro yeast without inclusion of fish meal or plasma. Individual pig weights were recorded at the beginning of the experiment, on d 14, and on d 28. Feed addition was recorded daily and the weight of feed left in the feeder was recorded on d 14 and 28. At the end of each phase (d 14 and d 28), blood samples were collected from 1 pig per pen and blood urea nitrogen (BUN), total protein, albumin, tumor necrosis factor-α (TNF-α), IL-1β, IL-10, and IL-6 were analyzed.

Results

Average daily feed intake of pigs linearly decreased (P < 0.01) from d 14 to 28 and during the overall experimental period, whereas G:F from d 14 to 28 linearly increased (P < 0.01) as the concentration of Sylpro yeast increased in the diets (Table 1). However, no differences among dietary treatments were observed in the overall experimental period for final body weight, ADG, and G:F. On d 14, albumin concentration of pigs linearly increased (P < 0.05) and concentration of TNF-α was linearly reduced (P < 0.01) as concentration of Sylpro yeast increased in the diets (Table 2). A quadratic increase (P < 0.05) in the concentration of total protein was also observed on d 28 in pigs fed diets with increasing concentration of Sylpro yeast. These results indicate that Sylpro in diets for weanling pigs may increase nutrient transport in the blood and reduce inflammation in weanling pigs.

Key points

• Increasing concentrations of Sylpro yeast resulted in improved G:F of pigs during the second phase of the experiment.
• Inclusion of Sylpro yeast in diets for weanling pigs positively influenced blood concentrations of indicators for nutrient utilization and inflammatory response.

Table 1. Growth performance for pigs fed diets containing increasing levels of Sylpro yeast¹

¹Data are least square means of 8 observations for all treatments.

²Sylpro yeast was sourced from Arbiom, Durham, NC; Phase 1 diets contained 0, 10, 18, or 26% Sylpro yeast, whereas phase 2 diets contained 0, 8, 14, or 20% Sylpro yeast.

³ADG = average daily gain; ADFI= average daily feed intake; G:F = gain:feed.

Table 2. Blood characteristics for pigs fed diets containing increasing levels of Sylpro yeast¹

¹Data are least square means of 8 observations for all treatments.

²Sylrpo yeast = Arbiom, Durham, NC; Phase 1 diets contained 0, 10, 18, or 26% Slypro yeast, whereas phase 2 diets contained 0, 8, 14, or 20% Sylpro yeast.

³BUN = blood urea nitrogen; TNF-α = tumor necrosis factor-α.