Written by: Dr. Jacquie Jacob, University of Kentucky
NOTE Organic poultry diets cannot include oil meals that have been produced through a solvent oil extraction method. They can, however, use oil meals that are a by-product of mechanical oil extraction..
A number of different oilseeds are used for the production of dietary oil. Oil can be extracted from oilseeds through solvent extraction or mechanical extraction. The means of extraction may affect the nutritional content of the meal made from the seed remnants after extraction. The examples below contrast the two means of extraction:
Camelina, also known as false flax, contains high levels of omega-3 fatty acids. Camelina meal is a new by-product from oil extraction for biodiesel production. Camelina meal contains secondary plant metabolites called glucosinolates that adversely affect broiler performance.
Cottonseed meal has less crude protein, dietary energy, and available lysine content than more commonly used soybean meal. Cottonseed meal also contains the antinutritional factors of gossypol and cyclopropenoid fatty acids. Glandless cottonseeds have been developed that almost eliminate gossypol in cottonseed meals.
Flaxseed is unique among oilseeds because it is high in alpha-linolenic acid. Flax is one of the most concentrated sources of unsaturated fatty acids available in feedstuffs for poultry. Oil composes 35% to 45% of the content of flaxseed, and 45% to 52% of that oil is alpha-linolenic acid.
Because the availability of peanut meal, also called groundnut meal, is low in the United States, and because peanuts have the potential for mycotoxin contamination, very little research has been done on the use of peanut meal in poultry diets. It is unclear whether allergens from peanuts are carried into the eggs and meat of poultry that have consumed peanut meal.
Safflower seed is a productive crop under semiarid or rain-fed conditions. Most of the US safflower crop is grown in California, primarily for the bird-feed industry. Safflower was originally grown for its flowers, which were used to create red and yellow dyes for clothing and coloring for foods. Today safflower is grown primarily for its oil, which is used for food and industrial purposes.
Sesame is primarily grown for use in human nutrition. Sesame seed meal is a by-product of oil extract. Compared to soybean meal, sesame seed meal is low in lysine, isoleucine, leucine, and valine. It is, however, a good source of the sulfur-containing amino acids, including methionine.
Soybeans—primarily in the form of soybean meal, a by-product of oil extraction—are the most commonly used protein source in poultry diets. Because of the presence of antinutritional factors, whole soybeans must be roasted before they can be included in poultry diets.
Sunflower seeds are a common oilseed. Sunflower seed meal is produced as a by-product of oil extraction. Seed processing times and temperatures affect the amount of lysine available in the final meal. The fiber level of the meal depends on the extent to which the seed hulls are removed prior to oil extraction. Maintaining higher levels of hulls improves oil-extraction efficiency, but it also increases the fiber content of the meal, reducing its potential as an ingredient in poultry diets. Variability in the percentage of hulls remaining after oil extraction is the reason that different sources of sunflower seed meal produce highly variable outcomes in poultry performance.