Biological and economic consequences of changes in voluntary culling policies

Document Type : Research Paper


Instructor of Department of Animal Science, Faculty of Agriculture, Tehran University, Tehran, Iran


The objectives of this study were to estimate and compare the biological and economic consequences of the implementation two policies including non-optimal and optimal culling decisions. For this purpose, data were collected during 2015 and 2016 from one of large dairy herds inIsfahan province. Then using different procedure of SAS software (NLIN, MEANS, LIFETEST), the biological parameters of this herd (including the shape of Lactation curve, risk of involuntary culling and probability of pregnancy in different milk periods and month in milk after calving) were estimated. In the following, by entering the biological and financial parameters to the bio_economic model developed in DairyVIP software, the herd status was simulated in different situations. The basis for optimal and non-optimal decisions were minimizing the opportunity cost and reach the daily production of non-pregnant cows to less than 20 kg, respectively. By implementing optimal policies, the annual culling rate increased from 31.9% to 41.9%, which resulted in an increase of 9,650,000 rials in heifers purchase cost. However, an increase in the revenue from the sale of milk calves and culled cow led to 3,390,000 Rials an overall improvement in net annual profit by each cow. The results of this research can help to change in dairy producer's attitude toward the replacement decision.


  1. Cabrera, V. (2010). A large Markovian linear program to optimize replacement policies and dairy herd net income for diets and nitrogen excretion. Journal of Dairy Science, 93, 934-406.
  2. Cabrera, V. (2012). A simple formulation and solution to the replacement problem: A practical tool to assess the economic cow value, the value of a new pregnancy, and the cost of a pregnancy loss. Journal of Dairy Science, 95, 4683-4698.
  3. De Vries, A. (2004). Economics of delayed replacement when cow performance is seasonal. Journal of Dairy Science, 87, 2947-2958.
  4. De Vries, A. (2006a). Economic Value of Pregnancy in Dairy Cattle. Journal of Dairy Science, 89, 3876-3885.
  5. De Vries, A. (2006b). Ranking dairy cows for future profitability and culling decision. In: Proceeding of 3rd Florida and Georgia Dairy Road Show, University of Florida, Gainesville. 91-109.
  6. De Vries, A. (2006c). The DairyVIP program to evaluate the consequences of changes in herd management and prices on dairy farm. Retrieved August 10, 2016, Animal Sciences Department of UF/IFAS Extension, from 
  7. Eicker, S. & Fetrow, J. (2003). New tools for deciding when to replace used dairy cows. In: proceeding 2003 Kentucky Dairy Conference, Lexington, KY. University of Kentucky, Lexington. 33-46.
  8. Kalantari, A. S., Mehrabani-Yeganeh, H., Moradi, M., Sanders, A. H. & De Vries, A. (2010). Determining the optimum replacement policy for Holstein dairy herds in Iran. Journal of Dairy Science, 93, 2262-2270.
  9. Kristensen, A. R. (1987). Optimal replacement and ranking of dairy cows determined by a hierarchical Markov process. Livestock Production Science, 16, 131-144.
  10. Lehenbauer, T. W. & Oltjen, J. W. (1998). Dairy cow culling strategies: Making economical culling decisions. Journal of Dairy Science, 81, 264-271.
  11. Lotfi, S., Lotfi, R., Vahidian Kamyad, A. & Farhangfar, H. (2014). Modeling the lactation curve of Holstein dairy cows using the Sine function and comparing it with Dijekstra and Wood’s functions in a herd of Holstein dairy cow. Iranian Journal of Animal Science, 45, 59-68. (in Farsi)
  12. Nielsen, L. R., Jorgensen, E., Kristensen, A. R. & Ostergaard, S. (2010). Optimal replacement for dairy cows based on daily yield measurements. Journal of Dairy Science, 93, 75-92.
  13. Smith, B. J. (1973). Dynamic programming of the dairy cow replacement problem.  American Journal of Agricultural Economics, 55, 100-104.
  14. Van Arendonk, J. A. M. (1984). Studies in replacement policies in dairy cattle I. Evaluation of techniques to determine the optimum time for replacement and rank cows on future profitability.  Zeitschrift für Tierzüchtung und Züchtungsbiologie, 101, 330-340.
  15. Wolf, C. A., Novakovic, A. M., Stephenson, M. W. & Knoblauch, W. A. (2014). Indicators of dairy farm financial Condition as Policy Triggers. Journal of Agribusiness, 32, 127-143