Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/20/2003
Publication Date: 8/20/2003
Citation: Soder, K.J., Rotz, C.A. 2003. Economic and environmental impact of economic and environmental impact of utilizing a total mixed ration in Pennsylvania grazing dairy herds. The Professional Animal Scientist. 19:304-311. Interpretive Summary: Economical and environmental concerns are stimulating changes in dairy production. As sustainable dairy farms are developed for the future, changes must be made to improve their economic and environmental impact. Low cost pasture based forage systems are a viable management alternative to more traditional stored forages for dairy producers. Supplementation of these cows is necessary to maintain milk production at acceptable levels. Research is limited regarding the economical and environmental impacts of alternative supplementation strategies on grazing farms; therefore, a systematic whole farm analysis was conducted to evaluate these effects on a representative Pennsylvania dairy farm. A grazing dairy farm was simulated using a total mixed ration (TMR) for supplement, and was compared with a similar farm either fed a concentrate while grazing, or fed a TMR in confinement. Utilizing a TMR in a grazing dairy herd resulted in a slight decrease in profitability when compared to the confinement farm, primarily due to lower milk production. Economic risk was higher for the confinement farm than the grazing farms. The concentrate-fed farm showed an environmental advantage over the other two farms, due to the increased exportation of excess forage from the farm. This study illustrated that using a TMR in a grazing herd may be a viable option to meet nutrient demands of grazing dairy cows while maintaining high levels of milk production and environmental sustainability.
Technical Abstract: Low cost pasture-based forage systems are a viable management alternative for dairy producers. A whole farm analysis was conducted to evaluate the potential long-term environmental impact and economic benefit of feeding either a concentrate or a partial total mixed ration (TMR) on grazing dairies. A representative dairy farm was simulated over 25 years of historical Pennsylvania weather using the Dairy Forage System Model (DAFOSYM). A representative grazing farm (100 ha) was simulated using two types of supplementation: 1) grain concentrate (GRAIN) plus pasture, or 2) a partial TMR (pTMR) plus pasture. These farms were then compared to an alfalfa and corn based confinement farm (CONF) on the same land base where TMR were fed year round. Annual milk production for the GRAIN, pTMR, and CONF farms were 7500, 9090, and 10,000 kg/cow, respectively. The CONF farm showed the greatest profitability ($710/cow annually) which was not much greater than the pTMR farm ($666/cow annually). Profitability was lowest for the GRAIN farm at $432/cow annually. Economic risk or year-to-year variation was highest for the CONF farm compared to the grazing (pTMR and GRAIN) farms. The GRAIN farm showed the greatest environmental benefit, probably due to greater exportation of forage. The GRAIN farm showed an environmental benefit compared to the CONF and pTMR farms by decreasing nitrogen leaching losses. Feeding a partial TMR to grazing dairy cows provides a viable feeding strategy to decreasing environmental impact while maintaining profitability.