Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2001
Publication Date: N/A
Interpretive Summary: When chickens are grown, the manure from the birds is commonly spread on fields as a fertilizer. Nitrogen is one of the natural products found in the manure that can pollute ground and surface water. The possibility of nitrogen pollution could be reduced if the manure simply had less nitrogen. The bird diet may be modified by adding essential amino acids and decreasing the total amounts of protein given the birds. Protein in the feed is the major source of nitrogen for development of bird tissues. This test on modification of protein contents was executed to measure the concentrations of nitrogen in the manure and to determine any adverse or beneficial effects of modifying the bird diet. Adding a small amount of the essential amino acid Threonine and large amount of raw protein released twice as much nitrogen in the manure as adding a moderate amount of Threonine to a minimal amount of raw protein. This was also the treatment with the greatest body weight gain. The immune system of the birds was unaffected by the different diets. Though the economics of Threonine treatments precludes its current use, it does provide an alternative method for reduction of potentially polluting nitrogen in poultry waste.
Technical Abstract: In a 2 x 3 factorial arrangement of treatments, the effects of dietary crude protein (19.0 and 22.5%) and dietary Threonine (0.6,0.7, and 0.8%)in Ross x Ross 308 male broilers were evaluated from days 5 to 15. At Day 5, 336 chicks were randomized across 48 battery pens (7 chicks/replicate and 8 replicates/ reatment). Essential amino acids, except Threonine, were in excess of NRC (1994) specifications and similar between both crude protein diets. Chicks receiving the 19.0% crude protein diet had increased (P<0.001) body weight gain and feed intake over chicks fed the 22.5% crude protein diet. Protein efficiency ratio was improved (P<0.001) in chicks fed the 19.0% crude protein diet. Similarly, chicks fed the 19.0% diet had reduced nitrogen excretion(P<0.043) in contrast to the 22.5% crude protein diet. Increasing dietary Threonine from 0.6 to 0.7% of diet improved (P<0.001) body weight gain and feed intake. Immune organ weights were not affected by dietary treatments. Feed gain was improved (P<0.016) in chicks receiving both crude protein diets as Threonine was increased from 0.6 to 0.7% of diet. However, chicks fed 0.8% dietary Threonine had lower (P<0.016) feed gain when fed the 22.5% crude protein diet. Male broiler chicks had improved growth performance measurements when fed 0.7% dietary Threonine. The nitrogen excretion was minimal for birds fed 19% crude protein and 0.7% Threonine and this value was half of that for birds fed 22.5% crude protein and 0.6% Threonine.