Protein sources in nursery diets

Dietary protein sources can be derived from plant or animal sources. Plant protein sources are typically less expensive than animal protein sources, but may contain various anti-nutritional factors. Animal protein sources are typically palatable and contain highly digestible amino acids, but variability in composition is often greater than plant sources. The interest in the use of plant-based protein sources is growing because of biosecurity concerns related to feeding animal-based protein sources.

Plant protein sources in nursery diets

Plant protein sources provide most of the protein in swine diets and soybean meal is the leading protein source. However, soybean meal might not be suitable to be fed as sole protein in the early post-weaning period.

Pigs have a transitory hypersensitivity reaction to soybean meal induced by allergenic proteins, namely glycinin and β-conglycinin, and indigestible carbohydrates of soybeans. Pigs experience a transitory period of poor nutrient absorption and low growth performance following the first exposure to a diet with high amounts of soybean meal (Li et al., 1990). The effects are transitory and pigs develop tolerance after 7 to 10 days (Engle, 1994). To alleviate the effects during this period, pigs are gradually acclimated to diets with increasing amounts of soybean meal after weaning.

The initial post-weaning diets should contain low amounts of soybean meal and then gradually increase soybean meal in the following nursery diets. The early exposure to soybean meal reduces the potential for delayed-type hypersensitivity reaction and adjusts the pig to diets containing soybean meal as the primary protein source. Furthermore, soybean meal can be further processed to remove the allergenic compounds and improve the utilization of soy proteins by weanling pigs (Jones et al., 2010).

Animal protein sources in nursery diets

Animal protein sources have been commonly used to minimize soybean meal inclusion in initial nursery diets and encourage feed intake in weanling pigs. Animal protein sources are typically palatable and contain highly digestible amino acids. However, animal protein sources are more expensive and variability in composition is often greater than plant protein sources.

Biosecurity concerns arise from the potential disease transmission via animal-sourced ingredients, particularly porcine-based. Animal protein sources typically undergo a thermal processing that eliminates most pathogens, but post-processing recontamination can be a concern. In addition, some pork marketing programs may limit the use of animal protein sources in swine diets.

Yeast protein source in nursery diets

Feed-grade amino acids

Feed-grade amino acids have been used to reduce specialty protein sources in nursery diets. The replacement of intact protein sources by feed-grade amino acids increases as feed-grade amino acids become available and economically justifiable. Currently, feed-grade lysine, methionine, threonine, tryptophan, and valine are all economical to include in nursery diets in the United States.

The use of feed-grade amino acids is key to meeting the amino acid requirements of nursery pigs, with accompanying reduction in dietary crude protein and savings in diet cost. However, it is important to ensure a sufficient supply of nitrogen for synthesis of non-essential amino acids when formulating diets with high levels of feed-grade amino acids.

Fact Sheet: Specialty Ingredients in Nursery Diets

Specialty ingredients in nursery diets