Tradeoffs between herd turnover rate and milk production for marginal cash flow and enteric methane intensity

Abstract

Longevity, productive lifespan, and culling are discussion top­ics among veterinarians, farmers, milk buyers and third par­ties such as NGOs. Further, the number of heifers to be raised as replacements is also of industry interest. It is sometimes proposed that having less replacement heifers and thus a lower herd turnover rate can lead to higher cash flow and lower enteric methane intensity associated with dairy production. Recently, some investigators have reported that cow culling de­cisions are made for farm investment decisions as opposed to poor health status (Owusu-Sekyere et al., 2023). Some European workers (Grandl et al., 2019) have investigated the association of length of productive life with greenhouse gas emissions and profit but included milk yields below what is observed on many U.S. dairy farms. There are likely trade-offs between replacing less productive cows with younger cows that possess greater potential for herd cash flow and enteric methane production at commonly ob­served or advocated turnover rates and milk production levels. Therefore, the objective of this work was to produce a math­ematical model using typical market prices, milk production levels, and turnover rates observed currently in the U.S. that examines these trade-offs.