EVALUATION OF ENHANCED TORULA YEAST WITH HYBRID STRIPED BASS Morone chrysops × M. saxatilis

Two separate trials were conducted to evaluate graded levels of  enhanced torula yeast (SylPro^® , Arbiom ) in the diets of hybrid striped bass and the digestibility of various nutrients and energy in this ingredient .  In trial 1, a basal diet was formulated to contain 43% crude protein and 11% lipid,  and  four incremental levels of enhanced torula yeast ( 5, 10, 20, and 30%) were added to the basal diet in place of  dehulled soybean meal on an equal-protein basis . A total of 10 fish (18.6±0.21g) were assigned to 15, 110-L glass aquaria connected as closed-recirculation system  with each diet fed to triplicate groups of fish for 9 weeks . In trial 2,  digestibility of a reference diet consisting of practical ingredients and a test diet consisting  of 80 % of reference diet and 20% of  the  enhanced torula yeast ingredient w as determined . A total of 15 fish (452.5±42g) were assigned to each of six , 1200-L fiberglass tanks connected as closed-recirculation system  with each diet fed to three replicate tanks for 21 days after which fecal samples were collected us ing the stripping technique.  In both trials, fish were fed twice daily at levels approaching apparent satiation .

In trial 1, a non-significant increasinge tendency was found  in weight gain, feed efficiency, and hepatosomatic index when fish fed with yeast-supplemented diets , except for those fed the diet containing 30% of yeast. Compared to the fish fed with basal diet, fish fed the  yeast-supplemented diets had higher whole-body lipid content and a significant difference was noticed  between f ish fed the diet containing 30% of yeast and basal diet . What's moreIn addition , according to the quadratic regression  relationship between dietary yeast levels and weight gain and feed efficiency, respectively, we can use 10.215 to 11.5% of yeast,  respectively, to re in  place  of  dietary soybean meal to drive a non-significantimproved better growth performance of hybrid striped bass .  In trial 2, digestibility coefficients for  protein, lipid, organic matter, and  energy were obtained for the yeast  product as shown in Table 1 .  Availability of various amino acids also was determined.  In conclusion, according to the digestibility results, enhanced torula yeast is well utilized by hybrid striped bass, and can substituted  for soybean meal  up  to 10 or 11% of diet  without  reducing growth performance.