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Winter Blues

May 25, 2005

By Peter J Lester

Cold brings with it an increased need for energy and that comes in the form of carbohydrates for animals and coal on the fire for us. Unfortunately, and all too often, farmers feel if the animal is provided with ample pasture all will be well. Sadly to say, that's not the case. 

Autumn saved pasture will contain around 22 to 25 percent protein and about 55 to 65 percent energy, as TDN. Animals under "normal" stress free conditions would require around 12 to 15 percent protein and 68 to 72 TDN. The term TDN refers to the Total Digestible Nutrient value of the feed. TDN encompasses all of the ingredients in the feed that can be converted and used as a source of energy. The term indicates the energy value of the feed and includes the sum of the digestible crude protein; the digestible fibre; the digestible nitrogen free extract; + the (digestible ether extract (Fat) times 2.25)) all of these can be used as a source of energy. The TDN value equals the sum of all of these feed constituents. 

As can be seen, protein is included in the equation and although autumn feeds contain more than enough protein, the TDN value is low. This being the case, the animal will now utilize the incoming protein as an energy source and will still be wanting for both energy and protein, as the protein was part of the TDN value and that value was a measure of the feeds potential energy, yet even with this high protein the potential energy was low. This will result in the animal utilizing the protein as energy by breaking off an amino group, forming urea and excreting it as urine. 

Protein burnt off to satisfy the animal's energy requirements is no longer available for tissue building or tissue restoration processes, resulting in loss of weight, or poor weight gains, re-absorption of the fetus and even death.

If you are feeding out hay, this is a perfect medium for potential energy. On its own, the TDN value may be as low as 55% and seldom runs higher that 65%. Animals feeding on this will always be under supplied with energy. By adding molasses at 600 mils of 50% molasses and 50% hot water, applied to the cut side of a small bale and left to stand for four days. If you are using large bales, or round, the same applies, just estimate the small bale equivalent. This will increase the calorific value of that hay by as much as 40%. 

Large bales can be placed in a trough with the molasses and water in the trough. Just use the forks and place the bale in the trough then pull it out and sit it down wet side up to let the liquid penetrate through the bale. Remember, if you are feeding out five small bale equivalents per day, you will need to apply the molasses to five days supply at first, then to one day's supply each day, leaving the last one to stand for the four days.

To this you can add minerals in the form of di-calcium phosphate, lime flour, magnesium oxide etc. Make sure the animals have access to salt all day every day. 

By now all animals should have been injected with vitamins A, D and E.