Effects of hydrolyzed and live yeasts on rumen microbial fermentation in a semicontinuous culture system (Rusitec)

Authors: HAKAN ÖZTÜRK, YASEMİN SALGIRLI DEMİRBAŞ, FARAH GÖNÜL AYDIN, İLKSİN PİŞKİN, FERHUNDE MELİS ÜNLER, MEHMET BAHRİ EMRE

Abstract: The objective of this study was to investigate the effects of hydrolyzed and live forms of yeast products from Saccharomyces cerevisiae on in vitro fermentation of a 50:50 forage:concentrate substrate using the rumen simulation technique (Rusitec). The Rusitec system consisted of nine fermentation vessels: three of them received daily 0.5 g/L hydrolyzed yeast, three vessels received daily 0.5 g/L live yeast, and three vessels received no additives (control). After an adaptation period of 7 days, the main fermentation characteristics were evaluated for 7 consecutive days. Ruminal pH was decreased (P < 0.05) by hydrolyzed yeast, whereas no effects were observed after live yeast treatment. Both hydrolyzed and live yeasts tended to increase butyrate production (P = 0.052). Acetate to propionate ratio was significantly higher (P < 0.05) for live yeast. Both products increased NH₃-N concentration, and it was significantly higher (P < 0.05) in live yeast in comparison with that in hydrolyzed yeast. Digestibility of dry matter was not significantly affected by both yeast treatments. Overall, these results showed that different types of yeast products in terms of their viability status had significant actions in ruminal microbial metabolism in different ways.

Keywords: Hydrolyzed yeast, live yeast, rumen, Saccharomyces cerevisiae

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