Response of four broiler strains to dietary phosphorus above and below the requirement when brooded at two...

Four strains of broilers (1,200 birds) were fed diets containing .14, .51, and .88% available phosphorus. The birds were raised for 3 wk at two brooding temperatures, 29.4 C and 35 C, with each being reduced 2.8 degrees per week. Feed consumption, feed conversion, body weight, bone weight (tibia), strength and percentage ash, and mortality were measured in order to assess broiler response. An increase or improvement in each measurement was observed from feeding diets containing .51% rather than .14% available phosphorus, but no further increase or improvement was observed in measurements by feeding diets containing .88% rather than .51% available phosphorus. The values for feed consumption, weight gain, and bone weight were significantly lower at the higher temperatures than at the lower temperatures. There were interactions of broiler strain-by-phosphorus with feed consumption, BW gain, and bone weight and strength; also, of temperature-by-phosphorus with bone strength, bone ash, and mortality. These interactions indicate that the bird's response to phosphorus is influenced by strain and environmental temperature.