Feeding management (Animal Science Update)
(Editor’s note: Michael Westendorf is with the School of Environmental and Biological Sciences at Rutgers University.)
Nutrient inputs on a farm consist of feed, animals, bedding and fertilizer.
Outputs are meat, milk, animals, crops and manure.
When inputs exceed an animal’s nutrient requirements then excesses may be lost in feed or barnyard waste, in manure, and in lot runoff, etc.
These losses may result in excess nutrients stored in the soil, lost in the groundwater or as surface runoff.
Farms should be seen as complete systems with inputs, outputs, storage, losses and recycling all occurring.
If nutrients are overfed, or if feeding is mismanaged, nutrient losses can result.
Water. Water is the most abundant, cheapest, and least understood of all nutrients required for livestock production.
Requirements vary with stress, weather, heat, cold, disease, productive state, work, exercise, etc., as well as water and salt content of the feed.
Intake is not related to runoff or contamination on the farm in the same way that overfeeding or unbalanced diets are, but water influences an animal’s ability to consume, digest and use feed.
Diets should be managed to reduce nitrogen (N) losses.
Protein is the chief N source in the diet and N can be a risk to water quality when mismanaged.
If an animal requires 16-percent protein in the diet and we feed 20-percent protein then the excess 4 percent (containing N) is lost in the manure.
Conversely, if an animal requires 20-percent protein, and only16 percent is fed then production will be limited to the 16-percent level and excess nutrients lost.
Nitrogen feeding strategies are different for all livestock species.
For example, ruminants (cows, sheep, goats, etc.) produce some protein in the rumen provided there are energy and N sources in the diet, this will lower overall N requirements.
With single stomached animals, like chickens, horses, and pigs, individual amino acids are the basis of diet protein formulation. (Protein is composed of individual nitrogen-containing amino acids). Commonly used feeds limiting in amino acids must be supplemented or balanced with other feeds.
Phosphorus management. When overfed, phosphorus (P) can contaminate the environment and water supplies.
Cereal grains fed to livestock often contain unavailable P.
Ruminants, such as cows or sheep, can use the P in cereal grains, but pigs, chickens and other single stomached animals may require supplementation to meet P requirements. Excess P may be excreted in manure and be an environmental concern.
Cut feed wastage. It is common for animals to spill or waste feed. Wasted feed is often wet, and will spoil and rot if left, and animals will not consume it.
Silage left in the feed bunk and not consumed will quickly spoil. It is common for animals to be fed on the ground; there is no greater source of waste than feeding animals on the ground; animals should never be fed on the ground near a stream.
Monitor health and disease. Sick animals are not productive but will continue to consume and excrete nutrients in the manure.
Animals should be on a consistent health and herd management program, vaccinated regularly, and monitored for health and sickness.
They should be on a regular parasite control schedule. It is important to test feed and water supplies if toxins or contamination is suspected.
Monitor feed and forage quality. High quality feeds should be utilized.
For ruminants to attain optimum production, it is essential that forages be of the highest quality.
Diets too high in fiber or rained on during production or that spoil in the silo, will result in lower levels of production, will be more expensive, and may result in greater levels of nutrient loss.
Feed variability. Every load of feed that comes out of the field during harvest or is delivered by the feed company is different from the previous load. Producers should understand the variability of feed and balance diets accordingly. Contact a feed or forage labs to test nutrient content.
Feed processing. Processing feed is helpful if animals are to digest and absorb nutrients.
Feed processing includes grinding, flaking, steam rolling, mixing and all processes that improve the availability of nutrients. In some cases processing is not necessary.
By-product feeds are fed to animals. These are by-products from other feed commodity industries, such as the production of distilled spirits and beer (brewer’s grains), wheat milling, corn milling, and other products such as citrus pulp, beet pulp, and whole cottonseed.
These make excellent feeds, but nutrient content is often variable.
Additives. Additives, supplements, hormones and antibiotics can help to improve animal performance.
These should be used as prescribed on the label, or under the care of a veterinarian. Products that improve nutrient efficiency will reduce excretion relative to production.
Proper animal feeding and management practices ensure that feed nutrients are not wasted or overfed, and feed efficiency is optimized. It is impossible for all nutrients to be in perfect balance, but one wants to come close to meeting animal requirements. In this way we can promote optimum animal productivity while manure is managed to maintain this “recycling loop.”
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