experiments were conducted to test the hypothesis that values for the standardised ileal digestibility (SID) of amino acids, concentration of metabolisable energy (ME), and the standardised total tract digestibility (STTD) of P in torula yeast are not different from values obtained in a commercial source of fish meal.


Nutrient digestibility results Greater (P < 0.05) SID of amino acids was observed in torula yeast than in fish meal (Figure 1), and a similar response was observed for the STTD of P with values of 91% and 68% in to- rula yeast and fish meal, respectively. However, there were no differences in the concentration of ME (dry matter basis) be- tween torula yeast (3,636 kcal/kg) and fish meal (3,611 kcal/ kg). The effect of inclusion of 1,000 units of microbial phytase on the STTD of P was also evaluated, but the response was not significant for either ingredient, which is likely because


the concentration of phytate in both ingredients was low. Overall, although the concentrations of amino acids and P are lower in torula yeast than in fish meal, the greater digestibili- ty observed in torula yeast resulted in similar values for con- centrations of digestible amino acids between torula yeast and fish meal.


Growth performance experiments


Following the three digestibility experiments, an experiment was conducted to test the hypothesis that fish meal and plas- ma protein can be replaced by torula yeast in phase 1 diets without compromising growth performance of pigs. A 2-phase feeding programme was used with d 1 to 14 as phase 1, and d 15 to 28 as phase 2 and the torula yeast diets were formulated based on the digestibility data for SID of amino acids, and the STTD P in torula yeast that were ob- tained in the digestibility experiments. Pigs were fed 1 of 4


▶ WEANING | JUNE 2020


Torula yeast contains highly digestible amino acids and can replace fish meal and plasma protein in diets for weanling pigs without affecting growth performance.


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