Poultry International - January 2008

synthesis of non-essential amino acids,

✷ supply of essential amino acids is less than required.

For example, if CP content is reduced from 19.0% to 14.2% in a maize-soybean meal diet, methionine content is reduced from 0.28% to 0.24%, while lysine content is reduced from 0.92% to 0.69%. The lysine content in the final diet is reduced more than methionine.

It may be possible to reduce CP content of the diets by two percentage points if essential amino acids are supplemented although some researchers have found that supplementing a diet with amino acids other than methionine, lysine, tryptophan and threonine may prove uneconomical.

It has been shown that there is greater scope for diets with reduced CP for layers, although others have achieved limited success with this practice. Lysine supplementation of diets with low CP ( 13.6%)

Practical matrix value for diet formulation depends on
the mean CP value and standard deviation of ingredients
Mean Standard Matrix CP
deviation value
0.8 8. 3
0.4 48.6
1.6 64.4
3. 2 47.7
0 58.6

Ingredient

Maize

Soybean meal

Maize gluten meal Meat and bone meal DL-methionine

Adapted from Roush et al., 1996

increased egg production, egg mass and egg weight in one experiment while in another, supplementing diets with other limiting amino acids (threonine, arginine and tryptophan) helped maintain performance by laying hens fed low-CP diets.

Feeding programmes - Phase feeding is one technique used to manage N excretion. Commercial phase feeding programmes may include as many as six phases to step down dietary CP (22% to 16%), amino acids and other nutrients for broilers. Similar reports on nutrient refinement can be applied to broiler breeders and commercial

8. 7

48.8

65.2

49.3

58.6

laying hens. Economics and convenience will most likely drive the implementation of additional phases of dietary protein.

Conclusions

Controlling nitrogen dynamics offers an economical method to control environmental pollution: reducing dietary crude protein reduces nitrogen excretion and ammonia emissions. Better knowledge of requirements will improve diet formulations. ◻