Robert A. Milligan

Modelling reproduction in a herd of dairy cattle.

Abstract A dynamic stochastic model to simulate the reproductive process in a herd of dairy cattle has been constructed. The next event scheduling approach was utilized with four events being specified: perturition, ovulation, embryonic loss and replacement. The control variables included in the model are first breeding policy ( 1BDG ), reproductive culling policy ( RCLG ), heat detection program ( HDPM ), breeding program ( BDPM ) and service sires selection program ( SSPM ). In addition, the model uses numerous endogenous variables such as parturition type (PRTY), oestrus behaviour (EBHV), cows fertility (CFTY), embryonic mortality (EBLS), non-reproductive culling rate (NRCL) and others. The model was evaluated against independent experimental results. The simulated result closely approximates the average reproductive performance and variability of reproductive performance in a dairy herd.

A stochastic simulation model for evaluating forage machinery performance

Abstract The selection of machinery on a dairy farm is the focus of the study. A simulation model is constructed that evaluates alternative forage machinery complements on New York State dairy farms. Attention is focussed on the machinery use, forage crop production and concentrate purchase. The key measure of performance is the total cost of acquiring feed for the dairy herd. The total cost includes the machinery investment and operating costs and the cost of feeds required to supplement that produced on the farm. The simulation model, written in Fortran, utilises a daily timestep. Each day the feasibility of machinery operation is determined, machinery operations are scheduled and the end of day status is determined.

Implications for Agriculture

Although a number of individuals oppose animal patents on moral or ethical grounds (see Brody’s paper), a large portion of the expressed concerns is based on economics. This is true in particular of owner/managers of small farms who have been buffeted by change in the farm sector to the degree that US farm numbers have declined by some 60 percent from 1950 to 1984 according to the US Department of Agriculture. Virtually all of this loss has been among the groups of smaller farms, and most studies project further attrition of small farms for the predictable future (US Congress, Office of Technology Assessment, 1986). It is no surprise therefore that among farmers the “family farm” advocates are the most vocal opponents of patenting animals (Huber, 1988; see also Sorensen’s paper).

Constraining Phosphorus in Surface Waters of the New York City Watershed: Dairy Farm Resource Use and Profitability

The New York City Watershed Agricultural Program seeks to reduce the potential for phosphorus movement from farms to surface waters. A “phosphorus index for site evaluation” (P-index) provides planners in the New York City Watershed Agricultural Program with a tool for identifying individual farm business, phosphorus related problems, and evaluating solutions. A linear programming model is employed to examine dairy farm resource use and profitability, with the P-index used to impose phosphorus movement constraints. Results indicate dramatic differences in farm resource use and farm business profitability depending on the level of the P-index. Small changes in the target index level result in large shifts in optimal resource use and business profitability. These differences illustrate that restrictions on phosphorus movement from land to surface waters potentially have major impacts on resource use and farm profitability in the New York City Watershed.

Economic Viability of Investing in Alternative Part-Time Cow-Calf Farms in the Northeastern United States

Cow-calf enterprises in the Northeastern United States are generally small and often the only agricultural enterprise of families with large off-farm incomes . In this paper, the economic viability of cow-calf enterprises to these investors is considered using a representative farm/economic engineering approach. Investments in farm real estate that is characterized by limited capability soil resources are found to yield negative labor and management incomes but to be economically viable when change in net worth and present value of family after-tax income are considered.