STATE COLLEGE, Pa. – Phosphorus and nitrogen-containing protein are well recognized as essential components to dairy cattle feed.
As a consequence, livestock nutritionists historically formulated rations with levels higher than recommended by the National Research Council.
But with increasing environmental concerns, new studies that pinpoint nutrient requirements, plus the need for profits, dairy managers now look to precision feeding.
Needs, methods. At the Pennsylvania Association for Sustainable Agriculture’s Farming for the Future Conference in February, a number of experts discussed the need for and methods for balanced dairy feeding.
Kelly O’Neill, an agriculture policy specialist with the Chesapeake Bay Foundation, pointed out that about 4,000 miles of Pennsylvania streams are impaired by agricultural pollution.
The primary source is excessive nutrients generated by livestock manure.
Additionally, 50 percent of the nitrogen and 60 percent of the phosphorus that Pennsylvania contributes to the Chesapeake Bay comes from agriculture.
Significantly, Pennsylvania has agreed to reduce 37 million pounds of nitrogen and 1.3 million pounds of phosphorus to the Chesapeake Bay annually.
The Chesapeake Bay Commission says the most cost-effective strategy to reduce the excess manure is by adjusting livestock and poultry feed formulations.
These diet modifications could reduce nitrogen by 30 percent to 50 percent and phosphorus by 40 percent to 60 percent.
For example, the foundation notes that phosphorus levels in dairy rations often are 130 percent to 160 percent of the cows’ needs.
The excess is excreted in manure.
Adverse effects. Virginia Ishler of Penn State University finds that excess nitrogen has adverse effects on dairy health and reproduction.
Ishler told the group that the objective of precision feeding is to reduce the excess nutrients.
Animals should be fed their nutrient requirements, especially nitrogen and phosphorus.
Improvements. Strategies to improve the nitrogen efficiency include improvements in forage quality with cropping, harvesting, and storage; nutrition with the proper levels of protein, carbohydrate, and amino acid; feed management with feed bunk management, forage testing, dry matter testing, and labor management; and monitoring performance with measurements of milk urea nitrogen and milk production.
Through extensive research including silage and other feed evaluations, ammonia emissions monitoring, and manure phosphorus measurements, Ishler recommends efficient feeding closer to cows’ requirements than common practice.
Thus, precision feeding improves the environment and enables dairy managers to increase profits.
University of Pennsylvania veterinarian Jim Ferguson illustrated the effects of phosphorus and nitrogen in dairy cow fertility.
Deficiencies, as expected, have such adverse effects that in earlier studies supplemental recommendations became the norm.
However, recent studies emphasize the need for proper balance of nutrients.
He noted that dietary phosphorus commonly fed on farms may be substantially reduced for satisfactory milk production while simultaneously reducing the quantity of phosphorus secretion.
An excess of nitrogen results in rumen degradable protein above the amount needed for rumen synthesis of microbial protein.
It is associated with reduced fertility, and may be more pronounced in stressed cows.
Experience. Dairy farmer Andy Bollinger shared his experience with precision feeding.
He currently milks 310 Holsteins of his 350 herd at his Meadow Springs Farm in Lancaster County.
Meadow Springs Farm uses all the manure produced on their 600 acres, Bollinger is not required to adopt a nutrient management plan since his 1.7 animal units per acre falls below the regulatory threshold in Pennsylvania.
The farm raises the cows’ forage and energy needs, while purchasing the protein requirements.
Bollinger’s milk production averages 85-88 pounds daily, with lactations averaging 26,000 pounds, 3.6 percent fat and 3 percent protein.
Prior to the precision feeding program, Bollinger’s cows produced 3.4 percent fat.
Analyzing. Bob Munson, a field investigator for the New Bolton Center, had the farm’s dairy feed analyzed.
Munson said that although Meadow Springs Farm’s milk production was increasing, the too-rich feed was depressing the fat content.
The speakers stressed that dairy feed must be continually tested to determine nutrient levels.
Depending on conditions, the frequency ranges from monthly to every three to four months.
In conclusion, it was recognized that environmental issues will not diminish.
Although the problems of the Chesapeake Bay has drawn attention to the water quality issue, many other areas and other States are faced with excess nutrient difficulties.
The standards for emissions in air quality are becoming more rigorous as well.
For healthy, productive, and profitable dairy herds, managers must aim for the proper balance of nutrients.
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