Modeling and genetics of parameters affecting phytate phosphorus bioavailability in growing birds
Ankra-Badu, Georgina Abena
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Genetic methods may be used to improve phytate phosphorus utilization by modeling factors that affect PPB. A model was developed to determine the main factors affecting PPB. The effects of each trait were on PPB were determined and showed that body weight, feed consumption and feed conversion ratio, had a negative effect on phytate phosphorus utilization whereas body weight gain, relative growth, and the bioavailabilities of total phosphorus, calcium, nitrogen and energy had a positive effect. The results of this study also indicate that the major factors affecting phytate phosphorus utilization (PPB) in birds were body weight at 4 weeks, calcium bioavailability, nitrogen bioavailability and energy bioavailability. There were differences between the sexes with regard to the factors affecting PPB. The predictive model showed that nitrogen bioavailability had a positive effect on the PPB of females but had no influence on males. The fact that body weight and feed consumption showed a negative relationship while relative growth had a positive effect shows that feed intake traits have to be corrected for bodyweight to account for differences in efficiency of utilization. The heritabilities and genetic correlations between the parameters were also determined. The genetic correlations (rg) between PPB and body weight at 4 weeks and nitrogen bioavailability were low whereas rg between PPB and energy bioavailability and calcium bioavailability were moderate and positive implying that selection for improvement in calcium and energy bioavailability may improve PPB.