GARNER, N.C., Nov. 18 (UPI) -- North Carolina turkey manufacturer Butterball said the Thanksgiving season may suffer a shortage of big, fresh turkeys at U.S. retailers. The company said the supply of fresh turkeys over 16 pounds might come up short in the lead-up to the Nov. 28 holiday due to a difficulty among some farmers in getting this year's turkeys to put on enough weight, CNN reported Monday. Butterball said the problem affects only the supply of fresh turkeys and the company's frozen turkeys will not be affected. "Butterball and its retail partners have ample supply of frozen whole turkeys of all sizes -- small, medium or large," the company said in a statement. "While there may be limited availability on some larger sizes of fresh turkeys, Butterball has shipped 100 percent of customer orders of frozen whole turkeys and products are in distribution across the country. We experienced a decline in weight gains on some of our farms causing a limited availability of large, fresh turkeys. "While we are continuing to evaluate all potential causes, we are working to remedy the issue. We sincerely regret the inconvenience that some of our customers have experienced as a result of this issue."