(one-year chicken production contract entered into with Tyson Breeders, Inc.; contract orally terminated for grower's poor performance; grower sued for breach of contract; trial court awarded grower damages based on one-year contract income due to oral termination rather than written as required by contract; judgment reversed and remanded to compute damages for lost profits during period of time that jury determines to be reasonable notice period; evidence of grower's conduct causing prior termination of earlier contract relevant).