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There are two environmental aspects to feeds and feeding. First is to reduce or change the inputs, thus reducing the amount of pollutants that is generated. The second is to improve housekeeping and management to contain or minimize the amount of pollutants that moves on to the larger environment. We can do both.
The two most notable contaminants from our livestock farms are nitrogen (N) and phosphorus (P). N comes through in the manure from the protein in the diets. There is always a background of N in manure from undigested feed passing through the animals' digestive tracts.
Cows and youngstock are never 100% efficient in using the protein; some is always excreted as part of the normal metabolism of the animals. And if we do not provide some extra protein to allow for the inefficiencies and losses in the system, the results are usually poor performance and less than acceptable production.
The real challenge is to manage our feeding and production systems to include high-quality feeds and to balance cattle rations to maximize the use of N, or protein, for maximum efficient production. The old practice of feeding some extra to compensate for poor feeds, poor diets or poor management just does not work from an environmental standpoint.
The same applies to P. For years, the strategy was to feed more P to compensate for any reproduction or breeding problem that was encountered. If some P worked, more was better. During the past few years, environmental concerns and the cost of P supplements has forced a reevaluation of mineral supplementation to be sure the amounts, sources and feeding strategies are appropriate to the bottom-line nutritional requirements and feeding systems. Across the industry, we have found that less P works, and production not only holds, but in many cases flourishes. In some cases, we have actually reestablished what the bottom limits are for P.
The results have made a difference. Manure analyses have shown a significant decline in P levels. Along with better manure management practices, P applications from manure are declining to approach the maintenance levels for P removal in many of our dairy farm cropping systems.
Where diets have been managed to maximize the utilization of dietary protein, N in the manure has dropped. In other cases where extra protein is still programmed, N-efficient diets have been evasive and manure N levels still high. With lower N levels and better manure application practices, N supplied from manure and crop requirements are coming into line.
Other dietary and herd management concerns involve sodium, excess potassium and the trace elements of zinc, copper and, in some cases, selenium. Zinc, copper and some other compounds are also concerns related to footbath treatment for hoof conditions.
The other environmental issue is containment. We have made a lot of progress to improve the storage and handling of our feeds, especially when it comes to silages. The runoff from silage bunks and feed storages can be the worst source of pollutants we generate on the farms. Silage leachate is often much worse than manure. Runoff feeds and feed debris are a serious source of nutrients leaving the farmstead.
Here are some guidelines for containing pollutants:
• Good housekeeping is basic. Cleaning up spilled feeds, the refusal piles and the waste silage piles is a good start. Bunk management practices such as covering silage, controlling pile runoff and engaging in smart packing procedures all contribute to reduced nutrient losses. Techniques such as lining the sides of bunks with plastic and enveloping the silage pile can reduce the amount of rainfall that runs through the silage and decrease the leachate runoff.
• Good unloading practices, including the use of defacers to minimize the exposure of feed to the weather, are part of a winning strategy. It not only preserves feed quality, but also reduces the exposure to rainfall and added nutrient-laden bunk runoff.
• Efficient feed bunk management to reduce the amount of overage fed will reduce refusals and reduce waste. Even though the refusals may be fed again down the food chain, hitting the amount to be fed to a group in the first place will reduce the waste all along the line.
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