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Recent advances in biorefining technology use lignocellulosic biomass as a source of second-generation sugars to produce protein sources such as yeast. Yeast such as inactivated Candida utilis produced from underutilized wood co-products is a potentially sustainable protein feed ingredient in diets for piglets. However, C utilis yeast grown on lignocellulosic biomass has not been previously tested in diets for pigs. Therefore, the aim of the present study was to determine the effects of a locally-produced C. utilis as a protein source on growth performance and digestive function of weaned piglets. For that purpose, a total of 48 piglets (average BW of 11.06 ± 0.84 kg) were weaned at 30 days of age. The piglets were fed one of four dietary treatments for 28 days: a conventional control diet with soybean meal, fishmeal, rapeseed meal, and potato protein (CTR), or one of three experimental diets containing 10, 20 or 40% crude protein (CP) from yeast (CU10, CU20, and CU40, respectively). Diets containing an indigestible marker (Y2O3) were provided from day 18 of the experiment for the determination of apparent total tract digestibility (ATTD) and apparent ileal digestibility (AID).
As a result, adding yeast to diets did not affect growth performance compared with the control. CU40 diet showed a had higher ATTD of CP and a higher ATTD of ash when compared with the control. The ATTD of neutral detergent fiber decreased in the CU40 diet compared with the control. The apparent ileal digestibility (AID) of ash increased in the CU40 diet compared with the control, while the AID of CP and amino acids was unaffected. Villi-height increased in jejunum and ileum, and villus-height:crypt-depth ratio increased in jejunum of piglets fed the CU40 diet compared with the control. Moreover, fecal dry matter increased linearly with increasing levels of C. utilis in the diets at day 7 after weaning and was higher for the CU40 group when compared with the control group at day 21 after weaning. Trypsin activity and mRNA expression of nine genes encoding for nutrient transporters in the jejunum did not differ among diets.
These results suggest that C. utilis could replace up to a 40% of CP from the main protein sources traditionally used in diets for weaned piglets while maintaining growth and improving digestive function.
Cruz, A., Håkenåsen, I. M., Skugor, A., Mydland, L. T., Åkesson, C. P., Hellestveit, S. S., Sørby, R., McL.Press, C and Øverland, M. (2019). Candida utilis yeast as a protein source for weaned piglets: Effects on growth performance and digestive function. Livestock Science, 226, 31-39. https://doi.org/10.1016/j.livsci.2019.06.003
