Most of the vegetable protein sources are by products of the vegetable oil manufacturing industry.
Seed structure… Outer most layer is called husk and there is an Inner layer also present. Beneath is the endosperm which is the starch portion of the seed. Inner most is germ which is source of proteins and oils. In oil seeds, germ portion is 35-45%. In energy grains (cereals), germ portion is 7-15%.
All vegetable protein sources are either cakes or meals.
Cakes… if mechanical extraction from oil seeds is performed. Cakes have 3-9% oil.
Meals… if solvent extraction from oil seeds is performed to extract oil. Meals have 2% oil.
Most common vegetable protein sources include soyabean meal, canola meal, rapeseed meal, sunflower meal and cotton seed meal.
General characteristics of all vegetable sources Meals:
- Protein value ranges from 25-49%. It is always below 50%.
- Dry matter is quite high and ranges from 87-91%.
- Most of the vegetable protein sources also contain a starch portion which makes them a high energy source.
- Crude fiber percentage is 7-14%.
- It is largest produced oil seed meal.
- It is available in hulled and dehulled forms. Dehulled form contains 47-49% protein which is maximum percentage of protein in any seed meal. Hulled form contains 44% protein.
Good Qualities… it is excellent source of well balanced amino acids. Only methionine is deficient.
- For poultry, soybean and corn are the ideal combination. By this, deficiency of methionine is also fulfilled from corn.
- Variation in amino acid profile is very low. Digestibility of the amino acids in soybean meal is 89%.
- It also contains sulfur amino acids which are very important in skeleton development.
- It is double zero variety of rapeseed. Rapeseed contains glucocinolate and erucic acid (antinutritional factors). In canola meal, these factors are removed by genetic engineering.
- It is second largest produced meal.
- It contains 34-36% crude protein. It is with 8.5% NDF which is quite low and indicative of good digestibility and high energy.
- It is not preferred in poultry due to bitter taste. Bitter taste is because of two antinutritional factors which are glucocinolate and erucic acid.
- Inclusion rate is 5-7% in any animal ration.
Highly produced oil seed meal. It is rich in methionine. That’s why combination of soybean and sunflower meal makes good poultry diet.
Limiting Factors… These include crude fiber, protein variation and tennins.
- Decortications of sunflower seed is not a preferable in oil industry. Mostly corticated meal is available containing 20% crude fiber. So it is limited in poultry diet.
- Protein variation is quite in dehulled and hulled sunflower meal. Dehulled contains 38% protein and hulled contains 48% protein.
Tennins… these are the factors having similar activity like trypsin inhibitors. These bind with proteins and inhibit different digestive enzymes.
Cotton Seed Meal:
- In large animals, it is prohibited due to presence of gossipol which is antinutritional factor causing many of the fertility problems.
- Presence of linter which is extra covering of seed increases fiber percentage and incidence of mycotoxins attack.
- In poultry diets, its use is also negligible.
- It is much inferior in 4 basic amino acids that are lysine, methionine, threonine, tryptophan.
- Digestibility of these amino acids is also much lower.
Corn Gluten Meal:
- It is available in protein percentage of 60% and 30%. Corn gluten containing some of the fiber and 42% of protein is known as corn gluten feed.
- Major limiting factor is presence of aflatoxins because of milling procedure known as wet milling of corn.