Improving Animal Efficiency

Production efficiency has been measured in many different ways over the past decades. When considering the viability and profitability of a farm, the efficiency of food production relative to the financial costs is the primary concern. On a global scale, when considering the limited availability of land for food production, we have often thought of the need to increase the efficiency of production per unit of land. However, with today's technological advancements enabling more and more production per acre, it is the efficiency of production relative to environmental damage this is of particular interest. The question has become: how do we maintain productivity while decreasing environmental damage, and at the same time stay in business?

Fortunately, we have already conducted a vast amount of research related to answering this question. Research has focused on improving the nutritional efficiency of animal production. For example, because protein is an expensive nutrient to obtain, we have continually improved our methods of feed analysis and diet formulation. As a result, we have discovered ways to reduce the amount of feed nitrogen (an element mainly found in protein), relative to the amount of milk or meat produced. This improved efficiency translates into producing more animal product with lower levels of manure N (Kohn et al., 1997). At the same time, we have selected crops and determined their nutrient requirements to improve their use of N in soils, and we have developed manure management practices to use manure nutrients more efficiently. The main reason for this research was to reduce the costs of food production by decreasing feed and fertilizer costs while producing the same or greater amount of product.

Most agricultural scientists specialize in specific aspects of the production cycle rather than integrate the various sub-components of the system. Nevertheless, farmers are required to consider the whole system and how the subcomponents add up. We have addressed these holistic concerns by developing a mathematical model of the animal enterprise.

The overall efficiency of nutrient utilization for the system is the amount of N in product divided by the total N inputs to the farm. This efficiency depends on the partial efficiencies of each subsystem. The potential range in partial efficiencies that might be expected for nitrogen on dairy farms is shown in the table below.

Subsystem Efficiency	Low	High
Animal Product N / Feed N	.16	.24
Feed N / Soil Available N	.50	.75
Soil Available N / Manure N	.25	.50

For example, the efficiency of a dairy herd would be the amount of product N divided by the total amount of feed used on the farm. Losses over time would be equal to the manure production and would result from spilled feed, feces, and urine. A 50% variation in manure production might result from feeding, ration formulation, and animal grouping systems. The apparent efficiency of crop production may range also by 50%. The range may result across crops, soils, harvesting methods, and fertilization methods. The availability of manure may range by 100% or more depending on manure collection, storage, and application methods. All of these ranges exclude practices that grossly mismanage resources such as applying too much fertilizer or grossly overfeeding of protein.

The predicted impact on the environment of changing the efficiencies of subcomponens to a farm are shown in the next table.

Ratio of N loss from the farm to product N, as affected by efficiency and source of N input to the farm.

Partial Efficiencies	N Input from Legumes	N Input from Fertilizer
All Low	4.9	10.2
Animal High	3.0	6.5
Crop High	4.5	6.0
Manure High	4.2	8.9
All High	2.1	3.0

Improving the efficiency of animal production relative to feed nutrients is the most important mechanism for reducing nutrient losses from the farm. The second most important means to reduce nutrient losses is to improve the efficiency of crop utilization of soil nutrients. This may be accomplished by choosing crop species that are best suited for nutrient uptake and high yields, and by applying the correct amount of fertilizer and available nutrients from manure. The losses from the farm would be reduced substantially by improvements to both herd and cropping systems.

The efficiency of manure conversion to soil available nutrients has the least impact on total farm losses. For example, an improvement in manure collection or storage to reduce N volatilization from manure would have a lesser impact on the whole farm nutrient use efficiency than a proportionally similar improvement in herd or crop management. None the less, gross losses in manure nutrients should be avoided. In contrast to improvements in animal nutrition which result in proportional or greater increases in whole farm efficiency , much of the conserved manure N is subsequently lost from the nutrient cycle before being translated into increased animal production.

The most important way to reduce nutrient losses to the environment for animal production systems is to improve animal efficiency to reduce manure nutrients and feeding for a given level of production. Ways to improve animal efficiency for dairy farms, and broiler farms, are provided.

Kohn, R. A., Z. Dou, J. D. Ferguson, and R. C. Boston. 1997. A sensitivity analysis of nitrogen losses from dairy farms. Journal of Environmental Management, 50:417-428. Order reprint

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