RESULTS
Growth performance. The effects of chitosan
supplementation on the performance of weaned
pigs are shown in Table 2. Quadratic improving
effect of chitosan supplementation on ADG was
observed during the first 14 days (P < 0.05) and
the last 14 days (P < 0.05) after weaning. The ADG
during the entire experimental period was also
improved quadratically (P < 0.01) with increasing
chitosan inclusion, and the pigs fed the diet containing
500 mg/kg chitosan had the highest ADG
among treatments. However, no significant linear
or quadratic effect was observed for the ADFI or
G : F ratio in response to increased chitosan supplementation
during the entire experimental period.
Nutrients digestibility. The effects of chitosan
supplementation on nutrient digestibility are shownin Table 3. With increasing chitosan supplementation,
the digestibility of DM improved linearly
(P < 0.01) and quadratically (P < 0.01) on day 14,
and tended to increase (P = 0.052) quadratically
on day 28. Compared with the control, diets with
chitosan quadratically increased the digestibility
of CP (P < 0.01), whereas linearly (P < 0.01) and
quadratically (P < 0.01) decreased the digestibility
of CF both on days 14 and 28. In addition, digestibility
of Ca and P was not affected by chitosan
supplementation on day 14. However, on day 28,
linear increase tendency (P = 0.056) for digestibility
of Ca and quadratic increase (P < 0.05) for
digestibility of P were observed with increasing
chitosan supplementation.
Digestive enzyme activities.The effects of chitosan
supplementation on the activities of pepsin,
amylase, and lipase are shown in Table 4. No significant
difference was found for the activities of
pepsin and amylase in the distal jejunum digesta
among the five groups on days 14 and 28. Chitosan
supplementation had no effect on the activity of
amylase in proximal jejunum on day 14, however,
on day 28, a quadratic increase tendency (P =
0.062) was observed with increasing chitosan
supplementation. The lipase activity of proximal
jejunum contents was not affected by increasing
chitosan supplementation on days 14 and 28. Dietary
chitosan linearly decreased the lipase activity
of distal jejunum compared with the control on
days 14 (P < 0.01) and 28 (P < 0.05).