Effect On the Growth and Development of Chickens When Cottonseed Is Substituted for Soybean in Their Diets

An inexpensive source of animal protein for internal consumption would be most welcome in Uzbekistan.  Toward that end, we are seeking new sources of plant protein that can safely be used as a feed for broiler chickens.  The Food and Agriculture Organization of the UN estimates that Uzbekistan produced more than 2,250,000 metric tons of cottonseed in 2009.  This cottonseed cannot be fed to non-ruminant animals such as chickens because it contains the animal toxin gossypol.  Gossypol occurs as two enantiomers referred to as (+)- and (-)-gossypol.  Most of the toxicity of gossypol resides in (-)-gossypol.  We are currently developing cotton plants that contain a high percentage of the less toxic (+)-gossypol in the seed.  To assess the potential usefulness of this new high (+)‑gossypol seed we have begun a series of chicken feeding experiments using commercially available cottonseed.  We now report the results of these early experiments. Chickens (60) were fed a standard diet (Control Diet), and diets in which 15% or 23.2% of the soybean meal was replaced with commercial cottonseed meal (15% CSM Diet, and 22.3% CSM Diet, respectfully).  Birds were weighed at the end of each week.  At the end of 1, 3, 5, 7 and 8 weeks, 12 birds were euthanized and samples of liver, breast and gizzard were freeze dried and submitted for gossypol analysis. Birds receiving the 23.2% CSM Diet exhibited some digestional distress; differences in body weight from this group and the control were evident after 4 weeks, and they weighed 10% less than those on the Control Diet after 8 weeks.  However, even after eight weeks, the body weights of the birds receiving the 15% CSM Diet were not statistically different than those on the Control Diet.  Results of postmortem examination of euthanized birds and levels of gossypol in animal tissue will be presented.