Evaluation of Torula yeast as a protein source in extruded feline diets

Abstract

The objective of this work was to evaluate the use of a Torula yeast on diet processing, palatability, and total tract nutrient digestibility in extruded feline diets. Four dietary treatments were compared, differing by protein source: Torula yeast (TY), pea protein concentrate (PP), soybean meal (SM), and chicken meal (CM). Diets were produced using a single-screw extruder under similar processing conditions. Palatability assessment was conducted as a split plate design where both first choice and intake ratio (IR) were determined. Apparent total tract digestibility (ATTD) of nutrients was estimated using Titanium dioxide as an indigestible marker. During diet production, specific mechanical energy (SME) of TY and SM (average of 187 kJ/kg) was greater (P<0.05) than for PP (138 kJ/kg); however, CM was similar to all treatments (167 kJ/kg). Kibble diameter, piece volume, and sectional expansion ratio were greatest for TY (P<0.05). Additionally, both bulk and piece density were lowest (P<0.05) for TY. Kibble hardness was lower for TY and SM (P<0.05; average of 2.10 Newtons) compared to CM and PP (average of 2.90 Newtons). During the palatability trial, TY was chosen first a greater number of times than CM (P<0.05; 36 vs 4, respectively), but differences were not found between TY and PP (25 vs 15, respectively) or TY and SM (24 vs 16, respectively). Cats had a greater IR (P<0.05) of TY compared to CM and PP (0.88 and 0.73, respectively). However, there was no difference in preference between TY and SM. ATTD of dry matter (DM) and organic matter (OM) was greater (P<0.05) for CM (87.43 and 91.34%, respectively) than other treatments. Both DM and OM ATTD of TY were similar (P<0.05) to PP and SM (average of 86.20 and average of 89.76%, respectively). Ash ATTD was greater (P<0.05) for cats fed TY and SM (average of 37.42%), intermediate for PP (32.79%), and lowest for CM (23.97%). Crude protein (CP) ATTD of TY was similar to all other treatments (average of 89.97%), but fat ATTD was lower (P<0.05; 92.52%) than other treatments (93.76 to 94.82%). Gross energy (GE) ATTD was greater (P<0.05) for CM than TY (90.97 vs 90.18%, respectively); however, TY was similar to PP and SM (average of 90.22%). Total dietary fiber (TDF) ATTD was similar between TY and CM (average of 66.20%) and greater (P<0.05) than PP and SM (average of 58.70%). The Torula yeast used in this study facilitated diet formation, increased diet preference, and was highly digestible when fed to cats.

Effects of feeding an inoculated corn silage with or without a direct-fed microbial on dry matter intake, milk production, and nutrient digestibility of high-producing lactating Holstein cows

“…Torula yeast has been categorized as a nutritional yeast when fed as an inactive microbial biomass for nutritional value ( Shurson, 2018 ). It has the ability to metabolize xylose and xylose oligomers ( Yanai and Sato, 2001 ), representing an opportunity to produce large amounts of microbial protein from a sustainable and cost-effective growth medium ( Holt and Aldrich, 2022 ).…”

Amino Acid Digestibility of Different Formulations of Torula Yeast in an In Vitro Porcine Gastrointestinal Digestion Model and Their Protective Effects on Barrier Function and Inflammation in a Caco-2/THP1Co-Culture Model

“…The protein source used in this research originated from wood biowaste or corn dextrose through transformation by yeast ( Cyberlindnera jadinii ), comparable to previous studies applied in aquaculture and pet feeding [ 15 , 16 , 17 , 19 ]. Overall, DDI and WDI had a closer composition profile than WSI, with higher assessed values of estimated protein digestibility obtained through measurement of AA absorption during the in vitro digestion procedure (around ~52–58%).…”

“…As an alternative to conventional protein sources, torula yeast ( Cyberlindnera jadinii ) has a high value because it can be cultivated on lignocellulosic waste biomass, does not rely on agricultural land use, has independent geographical cultivation, and has proven to be an excellent source of highly digestible AA [ 13 , 14 , 15 , 16 ]. It has been effectively incorporated in diet formulations for cats [ 17 ], poultry [ 18 ], pigs [ 15 , 16 , 19 ], and multiple aquaculture species [ 20 , 21 ]. Torula yeast can assimilate pentoses, including xylose and arabinose, and other carbon sources, such as organic acids, alcohols, propionaldehyde, and acetaldehyde.…”

Evaluation of Effective Energy Values of Six Protein Ingredients Fed to Beagles and Predictive Energy Equations for Protein Feedstuff

“…Yeast extract is the water-soluble extract produced from yeast waste streams, such as Saccharomyces cerevisiae , and separated from inner yeast cells. It could be a functional source of nutrients, since yeast extract is rich in proteins, amino acids, nucleotides, sugars, and a variety of trace elements [ 14 ]. Lin et al showed that yeast products may be beneficial to adult dogs by positively altering the gut microbiota, enhancing immune capacity, and reducing inflammation [ 15 ].…”