Dried blood meal is commonly used as a high-quality protein source in nursery pig diets. Growth studies have indicated that blood meal can be a better protein source than dried skim milk, fish meal, and soy protein concentrate. However, the growth effects of blood meal vary across studies; this may be due to differences in protein quality.
Limited data exist on digestibility of crude protein and amino acids in blood meal produced from different species and with different drying methods. Therefore, an experiment was conducted to measure apparent (AID) and standardized (SID) ileal digestibility of crude protein and amino acids in two sources of blood meal.
The experiment
Four diets were used in the experiment. Three of the diets contained protein: one diet was based on casein, one was based on a mixture of casein and spray-dried porcine blood meal, and one was based on casein and drum-dried bovine blood meal. The final diet was an N-free diet that was used to measure endogenous protein and amino acids lost from the animals themselves. Pigs were fed one of the four diets in each of four 7-day periods. Ileal digesta were collected on days 6 and 7 of each period, and analyzed for dry matter, crude protein, and amino acids. SID was calculated by correcting AID for endogenous protein and amino acid losses.
The results: amino acids are highly digestible in both sources of blood meal
The results from the experiment are summarized in Table 1. Both blood meal sources were high in crude protein. Both had similar concentrations of indispensable and dispensable amino acids, with the exception of methionine, which was present at twice the concentration in spray-dried porcine blood meal compared with the bovine blood meal. In both sources, concentrations of isoleucine, methionine, and cysteine were low.
There was no difference in the SID of crude protein between the two blood meal sources. This is consistent with a study published by Kats et al. in 1994, which found no difference in growth performance of weanling pigs fed blood meals of different animal origins. Spray-dried porcine blood meal had greater SID of indispensable amino acids compared with drum-dried bovine blood meal (P < 0.05). In particular, SID of lysine was greater in spray-dried porcine blood meal than in drum-dried bovine blood meal (P < 0.05), indicating that the heat involved in the drum-drying process may have damaged the lysine in the bovine blood meal. The SID of most dispensable amino acids, as well as total dispensable amino acids, was not different between the two sources.
Table 1.Concentration, AID and SID of crude protein and amino acids in blood meal from two different sources
|
|
Concentration |
AID |
SID |
|||
|
|
Blood meal source |
Blood meal source |
Blood meal source |
|||
|
Item |
Spray-dried porcine |
Drum-dried bovine |
Spray-dried porcine |
Drum-dried bovine |
Spray-dried porcine |
Drum-dried bovine |
|
CP, % |
98.21 |
94.98 |
66.2 |
63.8 |
83.6 |
81.7 |
|
Indispensable AA, % |
|
|
|
|
|
|
|
Arg |
3.51 |
3.27 |
70.7 |
68.2 |
89.8 |
88.1 |
|
His |
6.63 |
5.91 |
92.5 |
88.1 |
96.0 |
92.2 |
|
Ile |
0.55 |
0.42 |
-8.2 |
0.5 |
63.1 |
71.9 |
|
Leu |
12.17 |
12.45 |
90.6 |
85.9 |
95.8 |
91.6 |
|
Lys |
7.73 |
8.59 |
89.5 |
83.9 |
96.2 |
90.5 |
|
Met |
0.64 |
1.28 |
73.7 |
67.9 |
91.2 |
84.3 |
|
Phe |
5.91 |
6.81 |
89.6 |
85.1 |
96.0 |
91.4 |
|
Thr |
2.50 |
3.77 |
59.7 |
62.0 |
89.9 |
88.2 |
|
Trp |
1.70 |
1.24 |
84.0 |
73.4 |
95.3 |
89.6 |
|
Val |
8.32 |
8.46 |
88.3 |
84.2 |
95.0 |
91.2 |
|
Mean |
-- |
-- |
85.8 |
81.5 |
94.6 |
90.6 |
|
Dispensable AA, % |
|
|
|
|
|
|
|
Ala |
7.06 |
7.58 |
86.6 |
82.5 |
95.2 |
90.9 |
|
Asp |
9.87 |
8.75 |
85.3 |
80.3 |
93.9 |
90.0 |
|
Cys |
0.62 |
0.53 |
57.1 |
51.9 |
86.3 |
87.2 |
|
Glu |
6.73 |
6.46 |
73.1 |
70.8 |
89.1 |
87.4 |
|
Gly |
4.15 |
3.69 |
41.4 |
32.3 |
85.4 |
81.3 |
|
Ser |
3.06 |
3.47 |
69.5 |
66.0 |
89.2 |
86.4 |
|
Tyr |
1.78 |
2.25 |
68.6 |
68.2 |
90.2 |
88.5 |
|
Mean |
-- |
-- |
52.0 |
51.0 |
81.6 |
80.1 |
|
All AA |
85.98 |
88.03 |
71.7 |
68.8 |
89.3 |
86.3 |
Key points
- Blood meal is high in crude protein, and is commonly used as a protein source in pig starter diets.
- The drying methods and animal sources used to make blood meal differ.
- Blood meal contains low concentrations of isoleucine and methionine; supplementation may be required.
- Overall, SID of crude protein and both indispensable and dispensable amino acids, except for isoleucine, was high in both blood meal sources.
- Neither the drying method nor the species used to produce blood meal affected digestibility of crude protein. Spray-dried porcine blood meal had greater SID of indispensable amino acids compared with the drum-dried bovine blood meal.
This research report is based on unpublished research by S. E. Boucher, R. C. Sulabo, and H. H. Stein.