Currently, the industry standard for protein in the nursery pig diets is spray-dried plasma. However, during the Porcine Epidemic Diarrhea Virus (PEDV) outbreak, the supply of animal plasma was restricted and this sparked interest in protein alternatives for the diet that could perform with the same benefits. Studies had been conducted assessing the role of whole egg on nursery pig performance and gut health, but few studies compared plasma and egg yolk. The purpose of this study was to examine the effects of egg yolk on nursery pig growth performance, gut microbial communities, and immune system.
The lead scientists working on this project from the department of animal science at the University of Nebraska – Lincoln were Dr. Phillip S. Miller, professor; Thomas Burkey, associate professor; and Samodha Fernando, assistant professor. Other research team members included Kelly Moore, Shana Barnett, and Melanie Trenhaile.
Seventy-two nursery pigs were placed in eighteen pens, each pen included two barrows and two gilts. These piglets were between twenty-one and twenty-four days of age when placed in trial. Three different diets were fed including a control, egg yolk, and blood plasma. The diet was fed to six randomly selected pens of piglets. Weekly, piglets and feeders were weighed. Blood and fecal samples were also taken.
No differences were determined between the different groups of piglets in Phase I (days 0-7) or Phase II (days 7-21). However, during Phase III (days 21-28) piglets fed egg yolk had a greater average daily gain (648 g vs. 539 g). Circulating immunoglobulin, gut microbial populations, and intestinal integrity did not favor one feed type over the other. It was noted that while the diet protocol had no effect on gut microbial community composition, the phase of the trial did effect this make-up.
When considering cost, the study found it was most cost efficient to use the plasma during Phase I and the egg yolk during Phase II. This was because during phase III, when the common diet was used, there was a carry-over effect on pig performance from those piglets fed egg yolks. At the time of the study, egg yolk cost $2.30/lb. and plasma cost $2.16/lb.
In summary, it was concluded that both egg yolk and plasma are adequate options for nursery pig diets when considering growth performance, circulating immunoglobulins, and biomarkers for intestinal integrity. Therefore, the decision to use egg yolk or blood plasma as a protein source in a nursery pig diet is really based on the cost of the protein at the time of feeding.
Additional research should be focused on the long-term cost effectiveness of the egg yolk in comparison to plasma as shifts within the egg market could potentially influence the use of egg yolk over plasma.
An in-depth Thesis has been prepared regarding this research and it is available here if you would like more information.