|Rotz, Clarence - Al|
Submitted to: Journal of Dairy Science
Publication Type: Abstract only
Publication Acceptance Date: 6/1/2004
Publication Date: 7/1/2004
Citation: Zartman, D.L., Rotz, C.A., Crandall, K.L. 2004. Economic and environmental feasibility of a four-year lactation model [abstract]. Journal of Dairy Science. 1. Interpretive Summary:
Technical Abstract: More competitive dairy production systems are needed to improve the sustainability of our dairy industry. To test a perennial lactation concept, a set of 4,259 DHI records demonstrates that about 1% of cows have produced over 20 kg/day for more than four years of continuous lactation. A dairy farm simulation model was used to evaluate the long-term performance, environmental impact, and economics of a conceptual typical dairy farm in Pennsylvania converted to a perennial system. In this system, cows lactated continuously for 4-yrs. Compared to a traditional 100-cow dairy farm with replacement heifers produced on the farm, use of 120 perennial cows with purchased replacements reduced supplemental protein feed purchases 11%, increased annual milk sales 20%, reduced manure production 17%, reduced soil N leaching loss 25%, and increased annual net return to farm management by $14,200 while maintaining a long-term phosphorus balance for the farm. Compared to a traditional 125-cow dairy farm where replacement heifers were purchased, use of 120 perennial cows with purchased replacements reduced supplemental protein feed purchases 12%, reduced annual milk sales 4%, reduced manure production 7%, reduced N leaching loss 7%, and increased the annual net return to farm management by $1,600. The economic feasibility of the perennial cow dairy farm was relatively insensitive to assumptions for herd replacement rate and cow mortality, moderately sensitive to milk and heifer prices, and very sensitive to the milk production maintained by the perennial herd. Thus, a perennial cow system can improve the economic and environmental sustainability of traditional dairy production if a similar level in annual milk production per cow can be maintained.