Sunflower meal and cottonseed meal can be used in place of soybean meal as protein sources for swine diets. The production of both involves heat treatment, to extract oil from sunflower seeds and cottonseeds and to reduce antinutritional factors. When heat is applied to feed ingredients in the presence of moisture, a series of chemical reactions known as the Maillard reaction may be initiated. In the Maillard reaction, amino acids and reducing sugars combine to form indigestible compounds known as Amadori compounds. These amino acids are therefore not available to the pigs. Lysine is particularly susceptible to the Maillard reaction. It is important to know the extent of heat damage in feed ingredients so that diets may be formulated that supply the appropriate amounts of digestible amino acids to pigs.
Little information is available about the effects of heat processing on amino acid digestibility in sunflower meal and cottonseed meal. Furthermore, equations to predict the concentration of digestible amino acids in sunflower meal and cottonseed meal from the analyzed nutrient composition have not been reported. Two experiments were conducted to determine the standardized ileal digestibility (SID) of amino acids in sunflower meal and in cottonseed meal fed to growing pigs, and to test if regression equations could be developed to predict the concentration of SID lysine in sunflower meal and cottonseed meal.
Experimental design
In Experiment 1, ten growing pigs with an average initial body weight of 23.1 kg were surgically equipped with a T-cannula in the distal ileum and fed one of five diets. Sunflower meal from a single source was separated into four batches; the first batch was not autoclaved, and the others were autoclaved at 130°C for 20, 40, or 60 minutes. Four diets that contained each of the four batches of sunflower meal were formulated. Sunflower meal was the only source of crude protein and amino acids in the diets. Finally, a nitrogen-free diet was used to determine the endogenous losses of crude protein and amino acids. Ileal digesta were collected after a five-day adjustment period to the diets, and analyzed to determine values for apparent and standardized ileal digestibility of crude protein and amino acids in each batch of sunflower meal.
Experiment 2 was conducted in the same manner as Experiment 1, with the following exceptions. The pigs had an average initial body weight of 35 kg. Cottonseed meal was fed instead of sunflower meal, and was autoclaved at 130°C for 15, 35, or 60 minutes.
Composition of sunflower meal and cottonseed meal is changed by heat damage
Concentrations of crude protein and total amino acids were decreased in sunflower meal that was autoclaved for 20, 40, or 60 minutes compared with sunflower meal that was not autoclaved (Table 1). The concentrations of lysine and reactive lysine in sunflower meal, and the lysine:crude protein ratio, decreased as time of autoclaving increased. Concentrations of neutral detergent fiber (NDF), lignin, and acid detergent insoluble nitrogen (ADIN) were all greater in sunflower meal that had been autoclaved for at least 40 minutes than in sunflower meal that was not autoclaved. The concentration of acid detergent fiber (ADF) was also increased in sunflower meal that was autoclaved for 60 minutes. The concentration of reducing sugars decreased as time of autoclaving increased. Furosine, which is released by acid hydrolysis of Amadori compounds, was present in greater quantities in sunflower meal that was autoclaved for 40 or 60 min than in sunflower meal that was not autoclaved. The decrease in reducing sugars and increase in furosine indicate that the Maillard reaction is taking place in sunflower meal that is heat treated.
The concentration of crude protein and most amino acids in cottonseed meal was not affected by autoclaving. However, autoclaving cottonseed meal for 15, 35, or 60 minutes decreased the concentration of lysine and reactive lysine compared with cottonseed meal that was not autoclaved. The lysine:crude protein ratio decreased as well. The concentration of ADF in cottonseed meal was not changed by autoclaving, but the concentrations of NDF, lignin, and ADIN all increased as time of autoclaving increased. The concentration of reducing sugars in cottonseed meal decreased as time of autoclaving increased.
Amino acid digestibility is decreased by increasing heat treatment of sunflower and cottonseed meal
The SID of crude protein and all amino acids in sunflower meal was reduced (linear, P < 0.01) by increasing the time of autoclaving (Table 2).
A quadratic decrease (P < 0.01) in the SID of crude protein and all amino acids in cottonseed meal was observed with increasing times of autoclaving (Table 3) up to 35 minutes. The SID of crude protein and all amino acids in cottonseed meal that was autoclaved for 15, 35, or 60 minutes was less (P < 0.05) than the SID of amino acids in cottonseed meal that was not autoclaved.
Regression equations can predict concentration of digestible lysine
The concentration of SID lysine in sunflower meal may be predicted (P < 0.01) from the concentration of analyzed lysine in combination with the concentration of reducing sugars (RS) using the following equation (all concentrations expressed in %):
SID Lys = -1.00 + 0.54 × Lys + 0.30 × RS (r2 = 0.85).
The concentration of SID lysine in cottonseed meal can be predicted (P < 0.01) using the following equation (all concentrations expressed in %):
SID Lys = 1.81 - 3.67 × ADIN (r2 = 0.68).
The concentration of reactive lysine may provide some indications of heat damage in sunflower meal and cottonseed meal, but reactive lysine was not shown to be the best predictor for SID lysine in sunflower meal or cottonseed meal in these experiments.
Key points
- In sunflower meal, both the concentrations and digestibility values of crude protein and amino acids are reduced as a result of heat damage. The concentration of lysine, the lysine:crude protein ratio, and the digestibility of lysine all decrease with increasing time of autoclaving.
- In cottonseed meal, the concentration of crude protein and most amino acids is unchanged by heat treatment. However, the concentration of lysine and the lysine:crude protein ratio decrease as a result of heat damage. Heat damage also reduces the digestibility of crude protein and amino acids in cottonseed meal.
- Concentrations of analyzed fiber components in sunflower meal and cottonseed meal are increased as a result of heat damage.
- Regression equations that use the concentrations of lysine, reducing sugars, and ADIN may be used to identify the nutritional quality of heat damaged sunflower meal and cottonseed meal.
Table 1. Chemical composition of sunflower meal and cottonseed meal subjected to increasing time of heat treatment
|
|
Sunflower meal |
|
Cottonseed meal |
||||||
| Not autoclaved |
Autoclaved at 130°C |
Not autoclaved |
Autoclaved at 130°C |
||||||
|
Item |
- |
20 min |
40 min |
60 min |
|
- |
15 min |
35 min |
60 min |
|
DM, % |
91.92 |
89.31 |
90.05 |
88.79 |
90.98 |
90.12 |
87.04 |
87.57 |
|
|
CP, % |
36.33 |
33.08 |
35.49 |
33.24 |
41.68 |
42.20 |
42.23 |
42.26 |
|
|
ADF, % |
21.6 |
22.8 |
19.87 |
24.12 |
18.78 |
16.89 |
17.92 |
17.96 |
|
|
NDF, % |
31.9 |
34.88 |
34.9 |
43.21 |
26.19 |
27.12 |
27.99 |
29.83 |
|
|
Lignin, % |
5.59 |
5.42 |
5.66 |
6.73 |
5.52 |
5.73 |
6.49 |
6.68 |
|
|
ADIN, % |
0.22 |
0.18 |
0.25 |
0.28 |
0.20 |
0.25 |
0.29 |
0.27 |
|
|
Reducing sugars, % |
4.64 |
4.43 |
4.18 |
3.74 |
3.59 |
3.47 |
1.76 |
2.31 |
|
|
Lys:CP ratio, % |
3.39 |
3.30 |
3.04 |
2.95 |
3.93 |
3.77 |
3.60 |
3.60 |
|
|
Furosine |
0.013 |
0.012 |
0.021 |
0.03 |
0.027 |
0.04 |
0.04 |
0.03 |
|
|
Reactive Lys |
1.21 |
1.08 |
1.05 |
0.94 |
1.61 |
1.54 |
1.47 |
1.48 |
|
|
Indispensable AA, % |
|||||||||
|
Arg |
2.74 |
2.50 |
2.61 |
2.44 |
4.45 |
4.43 |
4.23 |
4.31 |
|
|
His |
0.84 |
0.78 |
0.83 |
0.81 |
1.16 |
1.14 |
1.13 |
1.16 |
|
|
Ile |
1.39 |
1.31 |
1.36 |
1.38 |
1.28 |
1.29 |
1.29 |
1.33 |
|
|
Leu |
2.17 |
2.03 |
2.16 |
2.13 |
2.35 |
2.39 |
2.38 |
2.46 |
|
|
Lys |
1.23 |
1.09 |
1.08 |
0.98 |
1.64 |
1.59 |
1.52 |
1.52 |
|
|
Met |
0.75 |
0.69 |
0.74 |
0.72 |
0.61 |
0.63 |
0.62 |
0.64 |
|
|
Phe |
1.56 |
1.45 |
1.55 |
1.53 |
2.14 |
2.17 |
2.17 |
2.23 |
|
|
Thr |
1.24 |
1.17 |
1.25 |
1.21 |
1.27 |
1.31 |
1.30 |
1.34 |
|
|
Trp |
0.51 |
0.46 |
0.44 |
0.43 |
0.50 |
0.51 |
0.49 |
0.48 |
|
|
Val |
1.71 |
1.60 |
1.68 |
1.68 |
1.77 |
1.77 |
1.78 |
1.85 |
|
|
All indispensable AA |
14.14 |
13.08 |
13.7 |
13.31 |
17.17 |
17.21 |
16.91 |
17.32 |
|
|
Total AA |
30.50 |
28.35 |
29.99 |
29.28 |
|
35.63 |
35.99 |
35.5 |
36.32 |
Table 2. Standardized ileal digestibility of CP and AA by growing pigs in sunflower meal subjected to increasing time of heat treatment
|
|
Not autoclaved |
Autoclaved at 130° C |
P-value |
||||
|
Item |
- |
20 min |
40 min |
60 min |
Linear |
Quadratic |
|
|
CP, % |
82.66 |
82.61 |
76.84 |
70.62 |
< 0.01 |
0.35 |
|
|
Indispensable AA, % |
|||||||
|
Arg |
92.53 |
92.06 |
89.26 |
86.52 |
< 0.01 |
0.55 |
|
|
His |
86.94 |
85.96 |
83.90 |
77.8 |
< 0.01 |
0.48 |
|
|
Ile |
87.58 |
87.55 |
85.77 |
81.44 |
< 0.01 |
0.83 |
|
|
Leu |
88.18 |
88.06 |
86.23 |
81.92 |
< 0.01 |
0.85 |
|
|
Lys |
83.15 |
81.24 |
74.83 |
63.52 |
< 0.01 |
0.96 |
|
|
Met |
92.8 |
92.32 |
91.58 |
87.82 |
< 0.01 |
0.25 |
|
|
Phe |
89.8 |
89.89 |
88.95 |
85.56 |
< 0.01 |
0.68 |
|
|
Thr |
84.63 |
84.17 |
80.84 |
74.38 |
< 0.01 |
0.96 |
|
|
Trp |
85.39 |
86.49 |
82.75 |
78.58 |
< 0.01 |
0.40 |
|
|
Val |
87.17 |
87.06 |
84.99 |
80.32 |
< 0.01 |
0.88 |
|
|
Mean |
88.49 |
87.95 |
85.68 |
80.66 |
< 0.01 |
0.79 |
|
Table 3. Standardized ileal digestibility of CP and AA by growing pigs in cottonseed meal subjected to increasing time of heat treatment
|
|
Not autoclaved |
Autoclaved at 130° C |
P-value |
||||
|
Item |
- |
15 min |
35 min |
60 min |
Linear |
Quadratic |
|
|
CP, % |
76.01 |
69.08 |
66.27 |
68.75 |
< 0.01 |
< 0.01 |
|
|
Indispensable AA, % |
|||||||
|
Arg |
88.39 |
84.44 |
81.67 |
84.55 |
< 0.01 |
< 0.01 |
|
|
His |
80.92 |
74.22 |
70.61 |
73.94 |
< 0.01 |
< 0.01 |
|
|
Ile |
70.71 |
62.23 |
59.51 |
64.93 |
0.04 |
< 0.01 |
|
|
Leu |
73.14 |
67.18 |
64.63 |
69.49 |
0.13 |
< 0.01 |
|
|
Lys |
66.21 |
54.42 |
49.75 |
54.10 |
< 0.01 |
< 0.01 |
|
|
Met |
71.91 |
66.21 |
63.67 |
68.44 |
0.12 |
< 0.01 |
|
|
Phe |
81.83 |
77.05 |
74.70 |
78.57 |
0.10 |
< 0.01 |
|
|
Thr |
70.53 |
64.32 |
60.34 |
65.09 |
0.05 |
< 0.01 |
|
|
Trp |
75.48 |
65.01 |
65.62 |
67.64 |
0.02 |
< 0.01 |
|
|
Val |
74.28 |
66.59 |
64.08 |
69.20 |
0.05 |
< 0.01 |
|
|
Mean |
75.34 |
68.20 |
65.49 |
69.56 |
0.01 |
< 0.01 |
|
This report is based on unpublished data by F. N. Almeida and H. H. Stein.