title: Assessing changes in the composition of broiler litters from commercial poultry units in Northern Ireland following the adoption of phytase in diets.
abstract: Microbial phytases increase the bioavailability of phytate P in poultry diets, and a survey was undertaken to determine if their use had lowered the P composition of broiler litter in Northern Ireland compared with standard values of litter composition listed in the current United Kingdom fertilizer recommendations. Litter samples were collected from a total of 20 units across Northern Ireland in 2010 and analyzed for DM, N, phosphate (P2O5), potash (K2O), magnesium oxide (MgO), water-soluble P (WSP), ammonium N (NH4N), and uric acid N. Dry matter of litter was positively correlated (P < 0.001) with N (r(2) = 0.65), P2O5 (r(2) = 0.63), K2O (r(2) = 0.56), and MgO (r(2) = 0.58). Negative correlations were observed between litter DM and WSP (r(2) = 0.45, P < 0.001) and NH4N (r(2) = 0.22, P = 0.038) contents. A standardized litter composition with a 60% DM gave a phosphate content of 13.7 kg/t that was 45% lower than the fertilizer book value (RB209), but there were only slight differences (<3%) between book values and DM standardized values for N and potash contents. Uric acid and NH4 contents were similar to published values. Mean N:P ratio (by weight) of litter increased from 3.7 in 2004 to 5.0 in 2010, lowering the risk of oversupply of P if land applications are targeted to meet N supply. Using the standard RB209 values to plan land applications of broiler litter to meet crop P demands risks undersupplying P, and there is a need for the regulatory values to be modified in light of the changing composition of broiler litter.
authors.affiliation: Agri-Food and Biosciences Institute, Agri-Environment Branch, Newforge Lane, Belfast, Northern Ireland BT9 5PX.
authors.forename: R H
authors.initials: RH
authors.lastname: Foy
authors.affiliation: Agri-Food and Biosciences Institute, Agriculture Branch, Newforge Lane, Belfast, Northern Ireland, BT9 5PX elizabeth.ball@afbini.gov.uk.
authors.forename: M E E
authors.initials: ME
authors.lastname: Ball
authors.affiliation: Agri-Food and Biosciences Institute, Agriculture Branch, Newforge Lane, Belfast, Northern Ireland, BT9 5PX.
authors.forename: J
authors.initials: J
authors.lastname: George
mesh_terms: D010832:6-Phytase / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002645:Chickens / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D008372:Manure / Q000032:analysis*; D009660:Northern Ireland; D010758:Phosphorus / Q000032:analysis*
chemical_list: D008372:Manure; D010758:Phosphorus; D010832:6-Phytase
keywords: ammonium; fertilizer supply; phytase; uric acid; water-soluble phosphorus