Economics of Finishing Pigs in Hoop Structures and Confinement: A Summer Group under Different Space Restrictions
The study was conducted at the ISU Rhodes Research and Demonstration farm. The two types of pork grow-finish production facilities compared in this study are hoop and total confinement. This is the eighth group of finishing pigs that has been evaluated in these facilities and the forth summer group. This study was conducted from April 2001 to September 2001. 
Past reports examined the differences between the two facility types to evaluate facility performance under summer and winter seasons. This report similarly examines the difference between the two facility types. An additional focus of this group is pig stocking density rates. Stocking rates of 9, 10.5, and 12 square feet per pig are evaluated for the hoop system. Net revenue per pig for the hoop systems were $19.79 (12 square feet), $22.41 (10.5 square feet), and $17.74 (9 square feet), respectively. The net revenue per pig for the confinement system was $16.25 per pig. 
The hoop facilities showed a dramatic drop in production efficiency when the facilities were stocked at a rate of 9 square feet per pig. The feed conversion increased nearly a tenth of a pound of feed per pound of gain and the average daily gain decreased by .6 pounds per day compared with the other stocking densities. However, feed efficiency and average daily gain only improved slightly when the space allowed per pig was 12 square feet compared with 10.5 square feet. Moreover, the reduction in space per pig from 12 to 10.5 square feet allowed a more efficient use of both facilities and bedding per pig. This allowed the group stocked at 10.5 square feet per pig to increase net revenue by $2.62 per pig over the hoop stocked at 12 square feet per pig. This difference is impacted somewhat by a difference in the weight of the pigs that were marketed (Table 1). They were on feed for a slightly longer time period. Despite this difference in sale weight the study suggests that a decrease in space utilized from 12 to 10.5 square feet per pig would increase the profit level for hoop facilities during the summer. 
Net revenue for the hogs from the hoop facility with 12 square feet of space was $3.54 per pig over the confinement system. This difference was greater than the average of the three previous summer groups, which favored the hoops by $1.43 and saw a difference in hoop net revenue vs. confinement net revenue that ranged from $.20 to $3.05 per pig. The range of differences can be explained by a number of reasons. Some can be attributed to on farm research variables such as weather and disease exposure. Another key issue is the distribution of marketing. This changes the performance of the remaining hogs as well as the average sale weight
Iowa Hoop Structures Used for Swine: A Survey
By surveying 13 area extension livestock specialists in Iowa, it was estimated that there are 2,100 hoop structures used for swine production in Iowa. Approximately 90% of the hoops are used for feeding market pigs and the remaining 10% are used for housing gestating sows. It was estimated there were 768 producers in Iowa with hoops for swine. Approximately 50% of the producers are estimated to use composting of manure and approximately 40% composted swine mortalities. Also, approximately 40% of the producers with hoops were involved with contract feeding of pigs in hoops. This number of hoops would be capable of producing 1 million market pigs annually. The rapid adoption of hoops by Iowa farmers is attributed to the low costs and versatility of hoop structures. Many niche markets are emerging for which hoop-reared pigs would qualify.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.