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 great source of energy and digestible amino acids in diets fed to weanling pigs. Previous experiments further demonstrated that increasing levels of SylPro yeast resulted in increased feed efficiency of pigs, which is likely a result of a positive effect of SlyPro yeast on intestinal health and immune function of pigs. However, there are no data to demonstrate effects of SylPro yeast on the immune response of pigs. It is also not known if SylPro yeast influences pig performance and intestinal health similarly as conventional torula yeast. Therefore, an experiment was conducted to test the hypothesis that inclusion of SylPro yeast in diets fed to pigs improves growth performance and intestinal health. The second objective was to determine if there are differences between the two torula yeast sources in influencing growth performance and immune response of pigs.
Experimental design
One hundred twenty weanling pigs (initial BW: 6.53 ± 0.78 kg) were allotted to 1 of 3 diets during phase 1, whereas all pigs were fed a common diet in phase 2. There were 4 pigs per pen with 10 replicate pens per treatment. In phase 1, the first diet contained 5% fishmeal and 3.5% plasma, and no SylPro/torula yeast. The second diet contained 14% SylPro yeast with 1.5% fishmeal and no plasma, whereas the third diet contained 14% conventional torula yeast with 1.5% fishmeal and no plasma. Individual pig weights were recorded at the beginning of the experiment, on d 7, d 14, and on d 28. Feed addition was recorded daily and the weight of feed left in the feeder was recorded on d 7, d 14, and d 28. Diarrhea scores were assessed visually per pen every other day using a score from 1 to 5. At the end of each phase (d 14 and d 28), blood samples were collected from 1 pig per pen to analyze for concentrations of cytokines.
Results
No differences were observed in any growth performance parameters (i.e., ADG, ADFI, G:F, final body weight) of pigs fed the experimental diets during phase 1, phase 2, and overall phase (Table 1). Pigs fed the diet containing SylPro or conventional torula yeast had reduced (P < 0.05) fecal scores compared with pigs fed the control diet on d 1 to 7 and during the first phase of the experiment (Table 2). However, when all pigs were fed the common diet during the second phase of the experiment, no differences in fecal scores of pigs were observed. On d 14, plasma concentrations of IL-1β, IL-8, and IL-12 in pigs fed the experimental diets were not different (Table 3). Pigs fed the conventional torula yeast diet had greater (P < 0.05) concentration of IL-2 compared with pigs fed the control diet, but was not different from that of pigs fed the SylPro diet. Greater (P < 0.05) concentrations of IL-4 and IL-10 were observed in pigs fed the diet containing SylPro or conventional torula yeast compared with pigs fed the control diet on d 14. On d 28, no differences were observed in concentrations of cytokines in plasma of pigs.
Key points
- SylPro yeast or conventional torula yeast can partially replace spray-dried plasma protein and fish meal in weanling diets without affecting growth performance of pigs.
- Dietary inclusion of torula yeast sources reduced fecal score and increased concentrations of the anti-inflammatory cytokines (i.e., IL-4, IL-10) indicating that these feed ingredients may improve intestinal health of pigs.
Table 1. Growth performance for pigs fed the experimental diets1
1Data are least squares means of 8 to 10 observations per treatment.
2SylPro yeast was provided by Arbiom, Durham, NC, USA.
3All treatments had 4 pigs per pen from d 1 to 7.
4ADG = average daily gain; ADFI= average daily feed intake; G:F = gain to feed ratio.
5All treatments had 3 pigs per pen from d 8 to 28.
Table 2. Fecal score of pigs fed the experimental diets1
1Data are least squares means of 10 observations per treatment.
2SylPro yeast was provided by Arbiom, Durham, NC, USA.
3Fecal score = 1, normal feces; 2, moist feces; 3, mild diarrhea; 4, severe diarrhea; 5, watery diarrhea.
a-bMeans within a row lacking a common letter are different (P < 0.05).
Table 3. Concentrations of cytokines in plasma of pigs fed the experimental diets1
1Data are least squares means of 9 to 10 observations per treatment.
2SylPro yeast was provided by Arbiom, Durham, NC, USA.
3IL = interleukin.
a-bMeans within a row lacking a common letter are different (P < 0.05).