ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

UREA

It is a nitrogen rich (46%), white, crystalline compound with the formula NH2-C=O-NH2. Rumen microbes hydrolyze urea with the help of urease enzyme and produce ammonia. The wastage of nitrogen may occur with excessive absorption of ammonia from the rumen leading to ammonia toxicity which cause ataxia, muscular twitching, tetany, excessive salivation, bloat and respiratory disorders. Urea should be given in such a way as to slow down its rate of breakdown and enhance NH3 utilization for protein synthesis. Rumen microbes require readily available source of carbohydrate to serve as energy for capturing ammonia and therefore urea diet should contain readily available carbohydrate so that the animal can satisfy the needs of its rumen microorganisms. One gram of urea should be given along with 0.13g of anhydrous sodium sulfate at the N:S ratio of 15:1 thus minimize sulfur containing amino acids deficiency. Urea does not provide energy, minerals, or vitamins to animals so adequate supplementation of these nutrients in diet is necessary. To avoid the danger of toxicity, frequent, small intake of urea is preferable.

Urea can provide 287.5 % of Crude protein (46 x 6.25). Rumen microbes hydrolyze urea with urease to produce ammonia. Excessive absorption of ammonia from the rumen leads to ataxia, muscular twitching, tetany, excessive salivation, bloat and respiratory disorders. Readily available carbohydrate and slow urea hydrolysis enables microbes to utilize ammonia effectively for microbial prolification. N:S ratio of 15:1 is necessary to avoid sulfur containing amino acids deficiency.

Urea mixed in concentrates

Growing and lactating ruminants are fed with urea, which is incorporated into the concentrate portion of the ration at 3% or at 1% of total dry matter intake through complete diet. The maximum safe limit is 136g of urea per animal over 260kg of body weight. Urea can be fed in several forms. It is available in solid blocks as urea molasses mineral blocks, which provide energy, vitamin and minerals. Intake of block is restricted by their high salt content and hardness of the blocks. There is some danger of excessive urea intakes, should the block crumble or should there be readily available source of water allowing the animal to cope with the high salt intakes. Solution of urea (Uramol) containing molasses and variable amount of vitamins, minerals are now in use. Urea is also used in the upgradation of poor quality roughages like paddy straw. Urea should never be fed to monogastric animals, birds and young rumiants.

Urea can be included at 3% of concentrate or 1% in complete diet. Maximum allowance 136g/animal Urea blocks with high salt and hardness  restrict intake. Urea should never be fed to mono gastric animals, birds and young ruminants.