Multistage optimization model for dairy production

Multistage linear programming representing 13 and 15-mo calving intervals (production cycles) of Holstein cows in northeast Texas was used to estimate income-over-feed cost for 5900, 6800, 7700, and 8600kg of 3.5% milk per lactation and six calving seasons. The linear program model directly accounted for loss or gain by stages of body weight during calving intervals. Milk and feed prices for each stage were corresponding means for 1971 to 1978. The response of income over feed cost to increased milk yield was essentially linear. Optimal solutions included weight losses that increased with yield of milk. Optimal repletion schedules varied by yield, with all gain during lactation for low milk yields and 40 to 75% during dry period for high yields of milk. Optimal rations for the region included corn, sorghum grain, cottonseed meal, wheat bran, defluorinated rock phosphate, urea, alfalfa hay, and Coastal bermudagrass hay and pasture. Energy concentrations of rations across the calving interval were more uniform, suggesting higher net income by reducing average ration cost, for weight loss or gain than for no weight loss strategies. Land requirements for forage were small and indicated many land use-capital investment paths for dairymen of this region. Income over feed cost for each milk yield did not differ between 13- and 15-mo calving intervals, indicating that the immediate penalty of extending calving interval can be hedged by multistage management.