Economic Studies Reinforce Efforts to Safeguard Specialty Crops in the United States.

Pathogen-tested foundation plant stocks are the cornerstone of sustainable specialty crop production. They provide the propagative units that are used to produce clean planting materials, which are essential as the first-line management option of diseases caused by graft-transmissible pathogens such as viruses, viroids, bacteria, and phytoplasmas. In the United States, efforts to produce, maintain, and distribute pathogen-tested propagative material of specialty crops are spearheaded by centers of the National Clean Plant Network (NCPN). Agricultural economists collaborated with plant pathologists, extension educators, specialty crop growers, and regulators to investigate the impacts of select diseases caused by graft-transmissible pathogens and to estimate the return on investments in NCPN centers. Economic studies have proven valuable to the NCPN in (i) incentivizing the use of clean planting material derived from pathogen-tested foundation plant stocks; (ii) documenting benefits of clean plant centers, which can outweigh operating costs by 10:1 to 150:1; (iii) aiding the development of disease management solutions that are not only ecologically driven but also profit maximizing; and (iv) disseminating integrated disease management recommendations that resonate with growers. Together, economic studies have reinforced efforts to safeguard specialty crops in the United States through the production and use of clean planting material.

Sequential feeding of whole wheat to growing broiler chickens.

1. Four broiler feeding trials were performed to examine the suitability of a whole wheat sequential feeding regimen for commercial broiler production. The sequential feeding programme gave a continuous cycle of ad libitum access to only whole wheat followed by the same time of access to only a pelleted diet. The pelleted diet provided a concentration of nutrients to balance that provided by the whole wheat. This was called a balancer diet. 2. The first trial used 144 cage-reared broilers from 28 to 49 d of age. Four different times of access (4, 8, 12 and 24 h) to the two alternate foods were compared. A whole wheat choice-feeding treatment and a complete single diet treatment were also compared. Whole wheat accounted for over 40% of the broilers' total food intakes when they were given the sequential feeding treatments of 8 h or greater. The whole wheat intakes of the birds given the 4 h sequential feeding and the choice-feeding were only 20 and 5% respectively. There was a non linear relationship between the weight gains of the broilers and the length of the sequential feeding period (P < 0.01). The growth rates of the broilers given sequential feeding were lowest (P < 0.05) in the 4-h feeding periods but highest (P < 0.05) in the 8-h periods. Weight gains decreased (P < 0.01) linearly as the sequential feeding periods were increased above 8 h. 3. A second trial, using 144 cage-reared broilers, examined the effect of different balancer compositions or different wheat varieties in 8-h sequential feeding. The broilers selected more whole wheat in their diet when they were given balancers with increased cereal contents. However, these broilers did not eat enough whole wheat to compensate for the reduced cereal content of the balancers and their overall diets had lower energy:protein ratios. The two different wheat samples did not result in any differences (P > 0.05) in the proportion of whole wheat selected by the broilers. 4. A third trial compared the diet selections, weight gains, food intakes and water excretions of 72 cage-reared broilers given whole wheat feeding regimens. The growth rates of the broilers given a loose mix of whole wheat and a pelleted balancer diet were similar (P > 0.05) to broilers given a complete single diet. The growth rates of these two groups were 7% greater (P < 0.05) than broilers given choice-feeding or 8-h sequential feeding.(ABSTRACT TRUNCATED AT 400 WORDS)