GENETIC-VARIATION OF PHYTATE PHOSPHORUS UTILIZATION FROM HATCH TO 3 WEEKS OF AGE IN BROILER CHICKEN LINES SELECTED FOR INCIDENCE OF TIBIAL DYSCHONDROPLASIA

Ability to utilize dietary phytate P was evaluated In 1,387 broiler ch icks of 45 sire and 180 dam families, by feeding a corn-soybean base d iet supplemented with no inorganic P and a low level of Ca. These chic ks were the progeny of high and lo ct incidence of tibial dyschondropl asia (TD) selected divergently for II generations and a nonselected co ntrol line. Chicks from the control line utilized phytate P better tha n those from the high or low Lines in terms of livability, mortality, and growth performance. Chides did not differ in mortality and body we ight between the high and low lines. Variation in livability and morta lity was greater among lines than among families, whereas families acc ounted for a greater part of variation than lines in body weight. Dams accounted for a slightly larger proportion of variation than sires in traits studied. Genetic selection for improved utilization of dietary phytate P could be effective.