Hydrolyzed feather meal is a co-product of the rendering industry that can be used as a protein source in diets fed to pigs. However, the variability in quality and digestibility between different sources of hydrolyzed feather meal has limited its use in swine diets. An experiment was conducted to determine the apparent (AID) and the standardized (SID) ileal digestibility of crude protein and amino acids in four sources of hydrolyzed feather meal. Because blood is sometimes added to feather meal during processing, the experiment also evaluated the effects on crude protein and amino acid digestibility of the addition of blood to feather meal.
Experimental design
A total of 100 growing pigs with an average initial body weight of 23.8 kg were allotted to ten dietary treatments. One diet contained soybean meal as the sole source of crude protein and amino acids. Eight additional diets were formulated based on soybean meal and one source of hydrolyzed feather meal each (with or without added blood) as the only sources of crude protein and amino acids. The digestibility of amino acdis in each source of feather meal was calculated as the difference between the digestibility of amino acids in the diet and the digestibility of amino acids in soybean meal. The last diet was a nitrogen-free diet that was used to determine the basal endogenous losses of amino acids.
Wide variability among sources of feather meal
The digestibility of crude protein and every amino acid was different among the four sources of hydrolyzed feather meal when no blood was added (Table 1). The mean digestibility of all amino acids did not differ between sources 2 and 3, but it was greater (P < 0.01) than the digestibility of all amino acids in source 4, which in turn was greater than in source 1. The addition of blood reduced (interaction, P < 0.05) the digestibility of crude protein in sources 1 and 4, but had no effect in sources 2 and 3. Adding blood had the same effect on the mean digestibility of all amino acids. The addition of blood increased (interaction, P < 0.01) the digestibility of lysine in sources 2 and 3, but had no effect in sources 1 and 4.
Key points
- Amino acid digestibility in hydrolyzed feather meal varies significantly among sources, probably due to differences in processing.
- The effect of the addition of blood to hydrolyzed feather meal also varies significantly among different sources of feather meal. In some cases, the addition of blood to feather meal reduces the digestibility of crude protein and amino acids; in other cases, it increases digestibility or has no effect.
Table 1. Standardized (SID) ileal digestibility (%) of crude protein and amino acids in hydrolyzed feather meal fed to pigs
|
|
FM 1 |
FM 2 |
FM 3 |
FM 4 |
|
||||||
|
|
No blood |
With blood |
No blood |
With blood |
No blood |
With blood |
No blood |
With blood |
Source |
Blood |
Source × blood |
|
CP |
67 |
57.4 |
70.9 |
76.3 |
71 |
70.5 |
69.5 |
60.9 |
< 0.01 |
0.08 |
0.02 |
|
Indispensable AA |
|||||||||||
|
Arg |
77.8 |
69.2 |
85.7 |
86 |
83.6 |
84.9 |
81.3 |
78.3 |
< 0.01 |
0.11 |
0.11 |
|
His |
56.9 |
34.4 |
69.1 |
64.8 |
66.4 |
77.1 |
67.2 |
56.6 |
< 0.01 |
0.16 |
0.1 |
|
Ile |
76 |
65.6 |
86.2 |
96.3 |
81.7 |
83.1 |
79.8 |
71.5 |
< 0.01 |
0.01 |
0.02 |
|
Leu |
70.8 |
58.7 |
80.5 |
81.2 |
76.5 |
77.3 |
75.4 |
67.2 |
< 0.01 |
< 0.01 |
0.02 |
|
Lys |
48.1 |
55.5 |
59 |
79.4 |
59.4 |
71.2 |
59 |
55 |
< 0.01 |
< 0.01 |
< 0.01 |
|
Met |
64.7 |
58.2 |
71.9 |
77.3 |
62.6 |
71.7 |
70.2 |
62.6 |
< 0.01 |
0.41 |
0.01 |
|
Phe |
73.7 |
61.7 |
83.3 |
83.5 |
79.6 |
80 |
77.3 |
70.1 |
< 0.01 |
< 0.01 |
0.03 |
|
Thr |
65.2 |
56.3 |
72.4 |
76.1 |
69.7 |
70.3 |
66.4 |
59.8 |
< 0.01 |
0.16 |
0.1 |
|
Trp |
67.4 |
73.7 |
84.6 |
85.2 |
85.9 |
81.8 |
83.8 |
79.8 |
< 0.01 |
0.91 |
0.39 |
|
Val |
72.4 |
60.2 |
82.9 |
83 |
77.4 |
79.9 |
77.6 |
69 |
< 0.01 |
< 0.01 |
< 0.01 |
|
Mean |
71 |
60.8 |
80.4 |
81.8 |
76.9 |
78.6 |
75.5 |
68 |
< 0.01 |
0.03 |
0.03 |
|
Dispensable AA |
|||||||||||
|
Ala |
66.9 |
53.7 |
76.1 |
80 |
73.2 |
75.4 |
71 |
64 |
< 0.01 |
0.08 |
< 0.01 |
|
Asp |
44.3 |
38.9 |
49.7 |
57.1 |
49.1 |
54.7 |
47.4 |
33.9 |
< 0.01 |
0.56 |
0.02 |
|
Cys |
53.2 |
45.3 |
60.5 |
61 |
58.4 |
57.5 |
62.3 |
53.8 |
< 0.01 |
0.09 |
0.42 |
|
Glu |
61 |
52.7 |
68.4 |
73 |
67.4 |
67.9 |
65.2 |
56.9 |
< 0.01 |
0.19 |
0.09 |
|
Gly |
66.8 |
55.9 |
73.3 |
78.9 |
74.8 |
75.4 |
71 |
67 |
< 0.01 |
0.39 |
0.12 |
|
Pro |
60.6 |
36.7 |
62.4 |
67.7 |
69.8 |
72.4 |
66.7 |
65.8 |
< 0.01 |
0.46 |
0.26 |
|
Ser |
74.6 |
66.9 |
79.7 |
81 |
78.4 |
75.2 |
73.1 |
68.5 |
< 0.01 |
0.03 |
0.26 |
|
Tyr |
65.9 |
57.9 |
76.2 |
78.9 |
72.7 |
73.9 |
72.4 |
69.1 |
< 0.01 |
0.32 |
0.16 |
|
Mean |
62.5 |
50.8 |
68.4 |
72.6 |
69 |
69.5 |
66.5 |
60 |
< 0.01 |
0.18 |
0.12 |
|
Total AA |
64.6 |
54 |
71.9 |
75.4 |
70.8 |
72.2 |
68.8 |
62 |
< 0.01 |
0.15 |
0.07 |
This research report is based on unpublished research by F. N. Almeida and H. H. Stein.