In conclusion, results of this study suggest that as egg
production declined and egg size increased toward the
end of the laying cycle, hens fed adequate levels of vitamin
D3 (HMD3) might have been able to deposit sufficient
quantities of vitamin D3 in the egg to maintain
excellent 16-d BWG and reduce the incidence and severity
of TD when fed a TD-inducing diet. The consistently
poorer growth and the higher incidence and severity of
TD for chicks from hens fed the LMD3 suggests that
these hens did not have sufficient vitamin D3 reserves
to deposit more vitamin D3 into the egg even when egg
production declined. In addition, EW rather than egg
production appears to be more important in determining
the quantity of vitamin D metabolites deposited in
each egg.
REFERENCES