A linear programming model was used to determine which crop rotations and weed management systems result in the highest net farm income for each of three farm sizes (120, 240, and 480 hectares) under alternative tillage systems. Test plot data for the years 1981 through 1988 from the Purdue University Agronomy Farm, which has highly productive, well-drained soils, were analyzed. Net incomes for no-till tillage systems on all farms in the model were consistently and significantly lower than incomes for moldboard and chisel plow tillage systems due to slightly lower yields and substantially higher herbicide costs. Generally, net farm incomes were slightly higher with a moldboard plow versus chisel plow tillage system. Also, as farm size increased, per hectare net incomes increased. About 80% of the time under moldboard or chisel plow tillage systems, the model chose as optimal the lowest of three herbicide application rates. A corn/soybean rotation was chosen as optimal on 56% of the farm area analyzed, versus 25% for continuous corn and 13% for a corn/soybean/wheat rotation.

Culture of hybrid striped bass Morone saxatilis × M. chrysops has been increasing in selected regions of the United States. Because of their thermal tolerance, hybrids may have potential as a new commercial aquaculture species in the Midwest. In these studies, hybrid striped bass were reared in cages located in southern, central and northern Indiana and offered one of three practical diets. Diets contained either 32, 36 or 40% crude protein. Additionally, a preliminary 8 wk laboratory experiment was conducted in which fish were offered the same diets. All diets were formulated to meet the established dietary lysine requirement; optimal levels of other essential amino acids in the diet were predicted by the whole‐body essential amino acid profile of hybrid striped bass. In the laboratory experiment, weight gain of fish fed 36% crude protein was significantly higher than those fed either other level of dietary protein. After 205 days, final average weight gains of fish in the field experiment were not significantly different and ranged from 233 to 426 g with an overall average daily gain of 1.6 g/fish/d. Overall survival was 89.1%. Dress‐out percentages were 81.2, 69.8, and 34.9% for eviscerated, eviscerated and headed, and fillets, respectively. Those values were not significantly different among dietary treatments or sites. Lipid content of fillets from fish fed 32% dietary crude protein was significantly higher than in fish fed 36 or 40% crude protein.

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