|Rotz, Clarence - Al|
Submitted to: Hoard's Dairyman
Publication Type: Trade Journal
Publication Acceptance Date: 9/15/2005
Publication Date: 2/25/2006
Citation: Zartman, D., Rotz, C.A. 2006. What about just keeping them in milk. Hoard's Dairyman. 151(3):118. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Our modern dairy cows have shown the ability to sustain high production for several years without being bred back. Should we look at this idea as a new herd management strategy? A perennial herd is one that has a planned lactation length greater than two years. We analyzed a national data base of dairy cow production records from the summer of 2003 and found over 4,200 records with lactations over 700 days. Among these were 26 cows with continuous lactations of about four years giving 85,870 pounds of milk with an average yield on their most recent test day of 47.5 pounds. These records and other information gathered from the scientific literature were used to develop a modeling study that tested the performance and profitability of perennial lactation herd management. As a basis of comparison, five herd scenarios were evaluated starting with a typical Pennsylvania dairy farm. The five scenarios were: 1) Standard management with 100 cows, 2) Standard management with 100 cows and no heifers, 3) Perennial management with 100 cows and no heifers, 4) Standard management with no heifers and 120 cows (to maintain a similar feed requirement and phosphate load), and 5) perennial management with no heifers and 128 cows. After these comparisons were completed, including evaluation of long-term farm performance, environmental impact, and economic consequences, the perennial herd of 128 cows was best. It exceeded the annual return to management of the typical base herd system by $3,200, reduced supplemental protein and mineral purchases by 38 percent, increased milk sales by 21 percent, and dropped nitrogen losses by 17 percent. The economic advantage over the normal lactation herd of 120 cows with all purchased replacements was even greater. Milk production was found to be a very important factor in the success of the perennial herd. An average lactation length of three to four years was also required to meet the profit potential desired. Replacement heifer costs and milk price also proved to be important determinants of profitability.