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The objective was to estimate economic effects of 19 generations of selection for increased litter size in the NE Index line. Using realized biological data, 1,250-sow enterprises based on Index line and Control line females were simulated. Each system was closed to introduction of females and included pureline females mated to produce replacement pureline and F1 gilts, and F1 females mated to terminal cross boars to produce market progeny. Costs of production and income statements were produced using the reproductive, growth and carcass data from the NE Index (I) and Control (C) lines reported in the two preceding papers. Gross revenues were estimated using the SiouxPreme Packing Co. grid payment matrix. The production system based on Index sows produced 24,417 pigs per year with net income of $23.76 per pig. The output for the system based on Control sows was 20,166 pigs with net income of $16.73 per pig. Within each mating group, net revenue for pureline I pigs was $2.05 per pig more than for Line C pigs and net revenue for three-way cross pigs with 25% Line I genes was $2.89 per pig more than for terminal cross pigs with 25% Line C genes. However, net revenue for F1 pigs with 50% Line C genes was $2.50 per pig more than for those with 50% Line I genes. Highly prolific lines such as Line I have a large effect on reducing production costs and increasing income. Crossbreeding is an effective way to utilize the enhanced reproductive efficiency of the Index line.