Nutrition requirements (Animal Science Update)
(Editor’s note: Michael Westendorf is with the School of Environmental and Biological Sciences at Rutgers University.)
Determining the adequacy of diets fed to livestock animals is more complicated than just knowing animal requirements or the nutrient and chemical analyses of feed. So then, what do we look for on a farm to evaluate the nutrition program?
A proper understanding of how to approach this will be of help to farm advisors, Extension agents, consultants, and, of course, all livestock farmers.
Climate or weather will always influence an animal’s nutrient requirements. In fact, many computerized nutrition programs currently make adjustments for weather or environmental conditions such as temperature, humidity, or wind speed.
An animal, for example, just like you and I, has a thermal comfort zone. For a cow, this comfort zone goes from about 40 degrees F to around 75 degrees F.
High humidity will intensify the effects of heat or cold. Above or below this zone animals will have to expend extra energy to regulate body temperature.
During hot summer months dairy cows will experience heat stress and feed intake and milk production may both decline.
Whenever this happens, it is essential that diets be formulated to increase energy and nutrient intake, and to employ some means, such as fans or sprinklers, to cool off the cows.
The same is true when the ambient temperature drops below the comfort zone.
Cows will need extra nutrients just to maintain condition and may also require shelter or other protection from the elements. Breed of cow will also influence the response to heat or cold.
Belted Galloways or Scotch Highlanders will tolerate much colder temperatures and cows with Zebu influence such as Brahman, Brangus, or Santa Gertrudis will tolerate hotter temperatures.
The upshot is this, when animals, not just dairy cows, don’t receive extra nutrients in response to extremes of heat or cold, they will adjust by using stored reserves of fat, protei, and other nutrients.
What else should be considered? Water quality and availability are essential if animals are expected to produce. When feed intake and animal production decline, the culprit may often be water intake.
Waterers need to be clean and water should always be in abundance. A small waterer for 50 cows is insufficient. Waterers must provide plenty of space for all animals to drink.
Quality is also essential. Water can be tested for nitrates, minerals, and/or microbial populations.
Contact a local Cooperative Extension Office if you suspect a water problem. Of course, when extremes in weather are experienced (heat or cold) water becomes doubly important and special measures should be taken to guarantee water intake is maintained.
General farm sanitation should also be considered.
An animal that is in an unsanitary environment, particularly one that also provides inadequate facilities for movement, resting comfortably, and socializing may also have depressed feed intake and performance.
Unsanitary conditions can be a general disease risk for animals. When facilities, particularly waterers or milking parlors, have poor electrical grounds, there may be a stray electrical flow which is uncomfortable to animals.
This can affect feed and water intake and ultimately production. Farm sanitation and animal comfort should always be given high priority if animals are to reach maximum feed intake and production.
Feed availability also needs to be considered. Are the feed troughs full? Is there plenty of space for all animals to eat?
Not all animals need unlimited access to feed as do high producing animals in various stages of growth, lactation, exercise, or egg production.
Some animals, such as gestating beef cows or gestating sows, or dry dairy cows, need to be maintained and should have adequate but not unlimited access to feed. In general, the feed troughs of highly productive animals should always be full and there should always be available space for all animals.
The consistency of manure can reveal either dietary or animal problems. Manure that is very loose or scoured could represent disease, parasites, or some other ailment. Manure that is too dry or hard could mean too much fiber in the diet or not enough water.
In the case of a dairy cow, very loose manure almost always indicates that too much concentrate and not enough fiber is present in the diet.
All the factors discussed here will influence how we feed animals. Others could be mentioned as well.
As described above, all of these are only indirectly related to animal requirements or dietary nutrient content, but can influence how we feed animals and/or help us to detect problems that should be corrected.
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