To Understand Animal Health Risks from Feeding Flood-Damaged Forages
With the significant drought issues in the West, forage availability and cost is at a premium this year. This situation further adds to current high feed cost problems. Penn State Extension Veterinarian Robert Van Saun, reports yet, another challenge now confronting dairy producers here in Pennsylvania is recent flooding conditions and its impact on forage quality and animal health.
The Pennsylvania Department of Agriculture has reviewed the flood damage situation carefully to evaluate potential toxic compounds and sewage contamination of forage to be harvested for feed. More information can also be found at the PDA website: http://www.agriculture.state.pa.us/portal/server.pt/community/pennsylvania_department_of_agriculture/10297 When at the PDA website then search under the term "flood".
Beyond the concerns of toxic contamination, a greater concern for the dairy producer is risk issues related to quality forage production and subsequent animal health. Producing high quality forage is the cornerstone to more profitable production in an environment of high feed costs.
What are the concerns to forage production and animal health with flood damaged forage? The primary concern with flooded forage is increased soil sediment on the plant to be harvested. Amount of soil contamination will depend upon duration and degree of floodwater coverage. One issue with increased soil contamination is greater ash or mineral content of the harvested forage. Increased mineral acts as a buffer to acids generated during the ensiling process. Thus the fermentation process will not generate a low enough silage pH to effectively inhibit activity of yeast or mold organisms. The resulting silage will be aerobically unstable; recognized as excessive heating in the silo or secondary heating when removed from the silo. These conditions would also be conducive to mycotoxin production by contaminating mold organisms.
Severity of soil contamination can be evaluated by total ash, iron, or acid-insoluble ash determinations from forage analysis testing. Work with your nutritionist or forage testing laboratory to interpret one or more of these values. To compensate for higher buffering activity from soil contamination one would need to increase the fermentation process by applying bacterial inoculants to the harvested forage. You may also need to evaluate plant nonstructural carbohydrate (NSC) content to ensure adequate substrate to drive the fermentation process. Additional sugar or starch sources may be added to the harvested forage when filling the silo.
Another concern with soil contamination of harvested forage comes from the potential risk for soil-borne bacterial spores adding to the plant's bacterial population. Spores from Clostridium and Listeria bacteria are of greatest concern relative to animal health risks. A wide range of Clostridium bacteria are found in nature with some being well-recognized disease pathogens of animals. Many dairy farms routinely vaccinate for seven to eight different Clostridial diseases. There is no practical way to determine clostridium pathogen exposure from silage. Diagnosis is made in the affected animals.
In addition to pathogenic Clostridium species, there are other Clostridium bacteria that can adversely affect silage quality and secondarily animal health. One specific organism, Clostridium tyrobutyricum, is primarily responsible for abnormal silage fermentation resulting in elevated quantities of butyric and isobutyric acids being generated. This organism will consume lactic acid and protein in silage to produce butyric acids and ammonia resulting in low lactic acid concentrations and higher silage pH. Growth of this organism is favored by high moisture (>70%) silages. Cows consuming butyric acid silage are at risk for ketosis as the butyric acid is converted to one of the ketone bodies, in the rumen. Thus transition cows should not consume butyric contaminated silage in an effort to minimize metabolic disease risks in early lactation.
Another risk often associated with clostridial fermentation comes from another spore-forming bacteria currently in the news, Listeria monocytogenes. Like Clostridia, Listeria is a soil-borne spore-forming bacterium that is common in the environment. Listeria is a significant disease that typically causes circling disease in cattle, but can induce abortions and meningitis in both cattle and humans.
Flood damaged forages add yet another challenge to the dairy industry this year. Soil and soil-borne bacterial spores can pose significant health risks to animals consuming flood damaged forage.
To Be Aware Of Projected Harvest Yields
Recently Pennsylvania Field Office of USDA's National Agricultural Statistics Service (NASS-PA) released some projections for the 2011 harvest. Corn yields, as of October 1, are forecast at 109 bushels in Pennsylvania, down 19 bushels from last year. Nationwide, at 148.1 bushels, yields are down 4.7 bushels from last year. If realized, this would be the lowest average yield since 2005. U.S. production is forecast at 12.4 billion bushels, down slightly from last year's production. If realized, this will be the fourth largest production total on record for the United States.
Soybean acres harvested is expected to be 485,000 acres which would be 10,000 less than 2010 acreage in Pennsylvania. Yield is forecast at 42 bushels, unchanged from last year. Pennsylvania production is expected to be 20.4 million bushels, down 2 percent from last year. Nationwide, production is expected to be 3.06 billion bushels, down 8 percent from the previous year. U.S. soybean yield is expected to average 41.5 bushels per acre, down 2 bushels from last year. If realized, this will be the second lowest average yield since 2003. U.S. soybean growers expect to harvest 73.7 million acres, down 4 percent from 2010.
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