Proof Positive – Soy-free Poultry Ration Research

By Jody Padgham

No Soy

With the development of faster growing, high nutrient-demanding animal breeds, the high protein content and low cost of soybeans have made them an important ingredient in many modern feeds. However, for the past several years producers have been approached by consumers requesting meat that has been produced using soy-free rations.

Poultry producers find this request especially challenging, as roasted soymeal is the standard protein used by the poultry industry, typically making up 30-40% of the weight of the ration. At 36-38% protein, contributing 1,000-1,600 Kcals/lb of calories, high in fat (16-20%), relatively available and low cost, soybeans are difficult to replace. Alternatives being explored include peas, sunflower meal, camelina meal, and fish and crab meal–but each has its limitations. Although market demand is driving exploration into soy-free poultry rations, the economic and production implications of this switch have been relatively unknown.

In response to the recent demand, research has been undertaken through the certified organic Penn State Dickinson College Farm in Boiling Springs, Penn., coordinated by Jeff Mattocks of the Fertrell Company, to compare results of feeding soy and soy-free rations to grass-fed broilers.

In the summer of 2012, three different breeds of naturally fed broilers (K-22 Red Broilers, Cornish cross and Bard Silver cockerels) were grown in three different types of pasture pens on three farms. Each farm raised only a single breed, split into two groups, treated exactly the same except one group was fed a soy ration and the other a soy-free ration.

Ration Formulas:

Each group contained 40 to 50 birds, raised in pens on pasture. Data was collected at each farm on the amount of feed consumed and weight gains of the birds.


Results show that the birds eating the soy diet grew significantly faster and larger than those in the soy-free group, even though the soy-free group ate more food per bird at two of the locations. Thus it can be concluded that those fed a soy diet were more efficient in their utilization of the feed. Since the soy-free ration cost 6.9 cents per pound more than the soy ration, the average cost of production for the soy-free birds was $0.90, $0.74, and $0.60 per pound carcass weight more on each of the respective farms.

Building on Prior Research

This 2012 research is an expansion and follow-up on research done at Dickinson College Farm in 2010. That research had birds on the Dickinson College farm only and used only K-22 red Broiler chickens fed in two groups using the soy and soy-free rations listed above. Results were similar to those shown in 2012, with birds fed a soy-based feed growing faster and larger than those fed a soy-free feed.

The analysis segment of this earlier research states: “Each population consumed significantly similar amounts of feed per bird and they were treated nearly identically. This, in conjunction with the representative weights of the birds (both live and processed) seems to indicate that the birds fed the soy-based feed were more efficient at utilizing feed for growth.

However, this is not necessarily suggesting that the feed consumed was the direct factor responsible for the weight gain. Among other discrepancies, there exists variation in caloric values, protein content, fat content, and moisture content in the feed. The weight difference could be attributable to a variation in overall health, vigor or grazing ability that arose from the dissimilarity in the feeds.

The decrease in feed consumed per body weight lends credence to the latter theory that the feed isn’t directly the cause of a larger bird. Given that growth continues to accelerate but the amount of feed consumed with regards to body weight decreases, it seems that birds are more heavily relying on grazing for their growth and body maintenance. Regardless, the data suggests that distributing the soy-based feed produces, on average, a larger bird. Furthermore, given the bird quality observations, it appears that the birds fed the soy-based feed were overall more robust and healthy. It should also be noted that the ratios of dressed weight to live weight were remarkably similar in each population.” (“No-Soy Ration Research,” Alex Smith, in Feeding Pasture-Raised Poultry by Jeff Mattocks, Fertrell Company, 2013)

For more information, see the publication Feeding Pasture-Raised Poultry by Jeff Mattocks, available from MOSES.

July/August 2013

Comments are closed.