Purpose
The day-to-day loss of animals is a fact of life all cattle producers must face and prepare for. Unfortunately, most published data of animal mortalities are for one-time, catastrophic die offs – where all the cattle on a farm must be exterminated because of disease outbreaks or natural disasters. Routine mortalities on cattle farms do not happen all at once, and mortality rates vary greatly between different life stages of animals and types of production systems.
An expert panel was convened by the Agricultural Working Group of the Chesapeake Bay Program to determine annual mortality, nitrogen and phosphorus masses produced by cow-calf, dairy and cattle on feed (feedlot) operations in the watershed. This paper concentrates on the annual mortality masses estimations determined by the panel. Cattle and Dairymen can use these values to plan for disposal of routine losses.
What Did We Do?
The panel looked, at depth, into existing production systems, and combined morality rates at different life stages, the size of animals at time of death, and the carcass composition varying with age to determine mortality and nutrient masses produced by typical cattle farms in the watershed.
The panel chose a 50-cow cow-calf operation as a model system, where cattle are on pasture 95% of the time. Under ideal conditions, each cow will yield one calf per year to be sold by year’s end. Some female calves will be retained to replace culled cows from the herd, maintaining the same general herd size. It was assumed there was no death loss of mother cows in the herd. We used USDA-APHIS (2010) data of average annual death loss of immature cattle combined with the average weight of cattle at different life-stages to determine weight of mortalities produced each year.
A total confinement beef feedlot was used to model mortalities for cattle on feed. Cattle were assumed to grow linearly with cattle placed in the feedlot at 400 to 600 pounds, and leaving at 1,000 to 1,200 pounds with an average time on lot of 120 days. Midwestern data (Vogel et al, 2015) was used to estimate annual deathrates per feedlot space at 30-day increments since placement in the feedlot.
A 100-cow milking herd was used as a reference for dairy systems. The reference farm contained 50 female calves and 50 heifers in development. Heifers are bred at 15 months and give birth around 24 months (2 years) of age. Male calves are exported from the farm as soon as possible for development as lower grade beef cattle. The reference dairy had heifers and dry cows on pasture, with the active milking herd in free-stall barns or alternative confinement for a 300-day lactation. USDA-APHIS (2016) data of average annual death loss of all types of dairy cattle was combined with the average weight of cattle at different life-stages to determine weight of mortalities produced each year.
What Have We Learned?
Figure 1 shows the estimated total weight of mortalities produced by a 50 cow, cow-calf herd each year broken down by age of animal dying. As can be seen in Figure 1, the greatest weight of mortalities occurred before calves were weaned – assuming no death of mother cows. The values in Figure 1 represent 1.52 calves born dead, 1.92 calves dying before weaning, and 0.87 head dying after weaning. This means a farmer should prepare for the loss of 2 newborn calves, 2 un-weaned calves, and one weaned steer/heifer per 50 mother cows each year. Dividing the total weight of mortalities by 50 head gives an average per cow annual mortality of 32 pounds per year.
Figure 2 shows the estimated total weight of mortalities produced by a 100-head-space feedlot. The greatest source of mortalities is steers and heifers weighing close to 700 pounds (31 to 60 days after arrival on the feedlot. Dividing the total weight of mortalities by 100 gives an average annual mortality weight of 18 pounds per head-space per year. The feedlot owner should prepare for approximately 3 animals dying each year per 100 head-space.
Figure 3 shows the estimated total weight of mortalities produced by a 100-cow dairy. Dividing the total weight of mortalities by 100 head gives an average annual mortality weight of 90 pounds per milking cow. The greatest source of mortalities is mature cows. Dairies should prepare for as much as 6 mature cows, 3 pre-weaned calves and heifers, and 1 weaned heifer dying each year per 100 mature cows.
Future Plans
Cattle producers can use the values estimated by this project to determine resources needed to prepare for mortalities. If burial is the preferred option, the space required to bury mortalities for the expected life of the operation; for composting, the area, and weight of carbon source required to compost; and for incineration, an incinerator capable of handling the largest animal housed on the farm.
Authors
Douglas W. Hamilton, Ph.D. P.E., Extension Waste Management Specialist, Oklahoma State University
Corresponding author email address
dhamilt@okstate.edu
Additional authors
Thomas M. Bass, Livestock Environment Associate Specialist, Montana State University; Amanda Gumbert, PhD., Water Quality Extension Specialist, University of Kentucky; Ernest Hovingh, DVM, PhD., Research Professor Extension Veterinarian, Pennsylvania State University; Mark Hutchinson, Extension Educator, University of Maine; Teng Teeh Lim, PhD, P.E., Extension Professor, University of Missouri; Sandra Means, P.E., USDA NRCS, Environmental Engineer, East National Technology Support Center (Retired); George “Bud” Malone, Malone Poultry Consulting; Jeremy Hanson, WQGIT Coordinator – STAC Research Associate, Chesapeake Research Consortium – Chesapeake Bay Program
Additional Information
Hamilton, D., Bass, T.M., Gumbert, A., Hovingh, E., Hutchinson, M., Lim, T.-T., Means, S., and G. Malone. (2021). Estimates of nutrient loads from animal mortalities and reductions associated with mortality disposal methods and Best Management Practices (BMPs) in the Chesapeake Bay Watershed (DRAFT). Edited by J. Hanson, A. Gumbert & D. Hamilton. Annapolis, MD: USEPA Chesapeake Bay Program.
USDA-APHIS (2010). Mortality of Calves and Cattle on U.S. Beef Cow-calf Operations: Info Sheet, 2010. Fort Collins, CO: USDA-APHIS.
USDA-APHIS. (2016). Dairy 2014: Health and Management Practices on US Dairy Operations, 2014. Report, 3, 62-77. Fort Collins, CO: USDA-APHIS,.
Vogel, G. J., Bokenkroger, C. D., Rutten-Ramos, S. C., & Bargen, J. L. (2015). A retrospective evaluation of animal mortality in US feedlots: rate, timing, and cause of death. Bov. Pract, 49(2), 113-123.
Acknowledgements
Funding for this project was provided by the US-EPA Chesapeake Bay Program through Virginia Polytechnic and State University EPA Grant No. CB96326201
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