Three hundred and sixty early-weaned barrows were fed diets containing increasing levels of added Zn from zinc oxide (0, 50, 100, 200, 400, 800, 1,600, 2,400, and 3,200
ppm). From d 11 to 21, growth performance improved with up to 100 ppm of added Zn
but was not improved further until pigs were
fed 3,200 ppm of added Zn. From d 21 to
36, pigs fed 100 ppm of Zn had the best growth performance. These results suggest
that a pig's basal Zn requirement is met with
100 ppm of added Zn from zinc oxide, but
adding 3,200 ppm Zn in early starter diets
results in further growth promotion. For
these reasons, 3,200 ppm Zn from zinc oxide
should be added to diets fed from weaning (8
to 10 lb) until 15 lb and a reduced amount in
subsequent diets.
