Yeast may be used instead of fish meal or other animal protein sources in diets for weanling pigs and there are several yeast proteins available. A newly developed enhanced torula yeast is derived from forestry by-products, and therefore, has a lower carbon-footprint compared with other yeast products. This enhanced torula yeast has an improved amino acid (AA) profile compared with traditional fermentation products, but at this time no data for the nutritional value of enhanced torula yeast fed to weanling pigs have been published. Therefore, 2 experiments were conducted to test the hypothesis that the AA and energy values of enhanced torula yeast is not different from that of fish meal. In Exp. 1, the apparent ileal digestibility (AID) and the standardized ileal digestibility (SID) of AA were determined, whereas Exp. 2 was designed to determine the concentration of digestible energy (DE) and metabolizable energy (ME) in both enhanced torula yeast and fish meal.
Experimental Procedures
The enhanced torula yeast was sourced from Arbiom Inc. (Durham, NC) and a commercial source of fish meal was also used (Table 1). Both ingredients were used in the two experiments.
In Exp. 1, 6 weanling barrows (initial BW: 11.7 ± 0.4 kg) were equipped with a T-cannula in the distal ileum and allotted to a replicated 3 × 3 Latin square design with 3 diets and 3 periods for a total of 6 replicate pigs per diet. Two cornstarch-based diets were formulated using enhanced torula yeast or fish meal as the only AA-contributing ingredients in each diet and a N-free diet was used to measure basal endogenous losses of AA. In each period, diets were fed for 7 days with ileal digesta being collected for 8 h on days 6 and 7. The ileal digesta were analyzed for AA to calculate AID and SID of all AA.
In Exp. 2, 24 barrows (initial BW: 14.4 ± 1.1 kg) were placed in individual metabolism crates and allotted to a completely randomized design with 3 diets and 8 replicate pigs per diet. The dietary treatments included a corn-based diet and 2 diets based on a mixture of corn and enhanced torula yeast or fish meal. Feces and urine samples were collected using the marker to marker approach with 5-d adaptation and 4-d collection periods. Samples of diets, feces, and urine were analyzed for gross energy to calculate concentrations of DE and ME in each ingredient.
Results
The AID and SID of AA in enhanced torula yeast were greater (P < 0.01) than in fish meal (Table 2), but there was no difference in the ATTD of GE between enhanced torula yeast and fish meal (Table 3). The concentration of DE in enhanced torula yeast tended (P < 0.10) to be greater than in fish meal, but if calculated on a DM-basis, no difference in the concentration of DE between enhanced torula yeast and fish meal was observed. The concentration of ME was also not different between the 2 ingredients.
Key points
- The AID and SID values for AA are greater in enhanced torula yeast than in fish meal.
- The concentration of DE and ME in enhanced torula yeast yeast is not different from fish meal
Table 1. Analyzed composition of ingredients (as-fed basis)
|
|
Ingredient |
|
|---|---|---|
|
Item |
Enhanced torula yeast |
Fish meal |
|
DM, % |
95.69 |
91.20 |
|
GE, kcal/kg |
4,600 |
4,320 |
|
CP, % |
52.37 |
64.17 |
|
Ash, % |
11.53 |
20.01 |
|
Indispensable AA, % |
||
|
Arg |
2.39 |
3.60 |
|
His |
0.91 |
1.17 |
|
Ile |
2.31 |
2.55 |
|
Leu |
3.42 |
4.22 |
|
Lys |
3.45 |
4.51 |
|
Met |
0.58 |
1.61 |
|
Phe |
2.10 |
2.44 |
|
Thr |
2.35 |
2.40 |
|
Trp |
0.62 |
0.55 |
|
Val |
2.79 |
2.94 |
|
Dispensable AA, % |
||
|
Ala |
3.33 |
3.98 |
|
Asp |
4.32 |
5.33 |
|
Cys |
0.49 |
0.47 |
|
Glu |
8.07 |
7.83 |
|
Gly |
2.27 |
4.74 |
|
Pro |
1.55 |
2.94 |
|
Ser |
1.97 |
2.04 |
|
Tyr |
1.67 |
1.68 |
|
Total AA |
44.59 |
55.00 |
|
Lys: CP ratio |
6.59 |
7.03 |
|
|
AID |
|
SID1 |
||||||
|---|---|---|---|---|---|---|---|---|---|
|
|
Ingredient |
|
|
|
Ingredient |
|
|
||
|
Item |
Enhanced torula yeast |
Fish meal |
SEM |
P-value |
|
Enhanced torula yeast |
Fish meal |
SEM |
P-value |
|
Indispensable AA, % |
|
|
|
|
|
||||
|
Arg |
92.6 |
78.3 |
1.76 |
< 0.001 |
|
99.4 |
83.0 |
1.76 |
< 0.001 |
|
His |
91.0 |
69.8 |
1.07 |
< 0.001 |
|
96.3 |
74.3 |
1.07 |
< 0.001 |
|
Ile |
90.2 |
71.5 |
0.92 |
< 0.001 |
|
93.9 |
75.1 |
0.92 |
< 0.001 |
|
Leu |
91.3 |
72.9 |
0.88 |
< 0.001 |
|
95.3 |
76.3 |
0.88 |
< 0.001 |
|
Lys |
91.7 |
73.1 |
1.13 |
< 0.001 |
|
95.2 |
76.0 |
1.13 |
< 0.001 |
|
Met |
90.3 |
74.8 |
0.99 |
< 0.001 |
|
94.5 |
76.3 |
0.99 |
< 0.001 |
|
Phe |
90.6 |
69.8 |
0.91 |
< 0.001 |
|
94.8 |
73.7 |
0.91 |
< 0.001 |
|
Thr |
78.8 |
65.6 |
1.13 |
< 0.001 |
|
86.2 |
73.4 |
1.13 |
< 0.001 |
|
Trp |
92.1 |
79.0 |
0.91 |
< 0.001 |
|
97.0 |
84.3 |
0.91 |
< 0.001 |
|
Val |
86.3 |
67.8 |
1.09 |
< 0.001 |
|
92.4 |
73.9 |
1.09 |
< 0.001 |
|
Mean |
89.5 |
72.3 |
0.95 |
< 0.001 |
|
94.5 |
76.6 |
0.95 |
< 0.001 |
|
Dispensable AA, % |
|
|
|
|
|
||||
|
Ala |
90.0 |
71.7 |
1.23 |
< 0.001 |
|
94.4 |
75.7 |
1.23 |
< 0.001 |
|
Asp |
87.1 |
57.6 |
0.96 |
< 0.001 |
|
92.0 |
61.8 |
0.96 |
< 0.001 |
|
Cys |
74.6 |
55.4 |
1.53 |
< 0.001 |
|
87.9 |
68.5 |
1.53 |
< 0.001 |
|
Glu |
92.1 |
72.2 |
0.72 |
< 0.001 |
|
94.9 |
75.3 |
0.72 |
< 0.001 |
|
Gly |
79.3 |
66.2 |
3.39 |
0.008 |
|
99.5 |
76.2 |
3.39 |
< 0.001 |
|
Ser |
81.9 |
65.2 |
1.39 |
< 0.001 |
|
89.2 |
72.8 |
1.39 |
< 0.001 |
|
Tyr |
89.8 |
67.7 |
0.95 |
< 0.001 |
|
94.1 |
72.3 |
0.95 |
< 0.001 |
|
Mean |
84.9 |
65.1 |
1.33 |
< 0.001 |
|
93.2 |
71.8 |
1.33 |
< 0.001 |
|
All AA |
87.6 |
69.3 |
1.10 |
< 0.001 |
|
93.9 |
74.6 |
1.10 |
< 0.001 |
1Values for SID were calculated by correcting the values for AID for basal ileal endogenous losses (n = 6). Basal ileal endogenous losses were determined (g/kg of dry matter intake) as CP, 16.14; Arg, 0.57; His, 0.18; Ile, 0.31; Leu, 0.49; Lys, 0.45; Met, 0.09; Phe, 0.32; Thr, 0.64; Trp, 0.11; Val, 0.62; Ala, 0.54; Asp, 0.77; Cys, 0.25; Glu, 0.86; Gly, 1.61; Ser, 0.52; and Tyr, 0.23.
Table 3. Apparent total tract digestibility (ATTD) of gross energy (GE) and concentration of DE and ME in enhanced torula yeast and fish meal fed to weanling pigs
|
Item |
Enhanced torula yeast |
Fish meal |
SEM |
P-value |
|---|---|---|---|---|
|
ATTD of GE, % |
88.88 |
86.35 |
1.60 |
0.188 |
|
As-fed basis |
|
|
|
|
|
DE, kcal/kg |
3850 |
3689 |
65.80 |
0.059 |
|
ME, kcal/kg |
3479 |
3291 |
74.76 |
0.119 |
|
DM basis |
|
|
|
|
|
DE, kcal/kg |
4023 |
4045 |
70.83 |
0.783 |
|
ME, kcal/kg |
3636 |
3609 |
80.20 |
0.820 |