Bioavailability of phosphorus from fossilized guano in broiler and layer chickens (Gallus gallus domesticus L.) diets

Experiments using three levels of available phosphorus (0.30, 0.35, 0.40%) were conducted on broilers and layers following a 2 x 3 factorial arrangement to determine the bioavailability of phosphorus from guano relative to MDCP [monodicalcium phosphate]. In the first experiment, 300 all-male broiler chicks were randomly distributed to six treatments, replicated 5 times, with 10 birds per replicate. In the second experiment, 90 individually caged 24-week old pullets were randomly distributed to six treatments, replicated 15 times, with one pullet per replicate. MDCP was replaced by guano on equivalent phosphorus level. Feeding trial lasted for 42 and 90 days for broiler and layer experiment, respectively. The source and level of available phosphorus had a significant interaction on ash and phosphorus of tibia of broilers. Guano had a phosphorus bioavailability of 31.62% relative to MDCP based on tibia ash as response criterion. Broilers fed diets with MDCP had significantly higher body weight gain, feed consumption and feed efficiency than those fed diets with guano. Feed consumption significantly increased while feed efficiency was significantly depressed with increased available phosphorus level in both diets. Source and level of available phosphorus in the diet showed a significant interaction on percentage livability while dressing percentage was similar for both sources at all levels of available phosphorus. Guano is more expensive than MDCP as source of phosphorus. Calcium and phosphorus contents of toes from pullet fed with MDCP were significantly higher than those fed with guano. The ash increased significantly from 0.30 to 0.35% available phosphorus while calcium content of toes of pullets significantly decreased from 0.35 to 0.40% available phosphorus. No significant differences were observed on all the performance parameters between source and among levels of available phosphorus except for egg production rate. Pullets fed with MDCP gave significantly higher egg production rate than those fed with guano. Pullets fed diets with guano had significantly greater body weight loss and lower income over feed cost compared to those feed diets with MDCP.