Effects Of Supplementation With Dietary Green Tea Polyphenols On Anthelmintic Ability And Growth Performance Of Lambs

The objective of this study was to determine the effects of supplementation with dietary green tea polyphenols(GTP) on insect resistant ability and growth of lambs infected with Haemonchus contortus; and provide a theoretical basis for production practice.Thirty male Ujumqin lambs were randomly assigned to five treatment groups for a 56 d feeding period. Treatments included:(1) uninfected as control(UNINF),(2) infected but not given GTP(INFGRP0) and(3)-(5) infected and fed 2, 4, or 6 g GTP/kg feed(dry matter basis; INFGTP2, INFGTP4 and INFGTP6, respectively).In the morning of 0d, 14 d, 28 d, 42 d, 56 d, all lambs were weighed; collected the fecal and blood samples to measure fecal egg count(FEC) by McMaster technique, packed cell volume(PCV), blood biochemical parameters and plasma AA profiles. During the 51-55 d, all lambs were collected the total fecal and urine samples to determined apparent digestibility of dietary nutrients. At the end of the feeding period, lambs were slaughtered to determine the adult Haemonchus contortus burden, the meat quality parameters and amino acid profiles.The results demonstrated the Haemonchus contortus infection decrersed the average daily weight gain and increased feed conversion rates in lambs(P<0.001), but did no affect dry matter intake or diet digestion. The FECs of all GTP-fed lambs were higher than those of uninfected lambs but of uninfected lambs, but PCV increased with increasing amounts of GTP supplementation. Furthermore, supplementation with different concentrations of GTP significantly reduced the numbers of adult Haemonchus contortus including both males and females(P<0.0001), and the Haemonchus contortus burden in INFGTP6 lambs was reduced to uninfected levels(P>0.05). The highest concentration of total protein was found in the INFGTP6 group on 56 d, and the lowest concentration was found in the INFGTP2 group on 28 d. Lambs in INFGTP0 group showed decreased meat color and antioxidant activities, however, feeding GTPs improved meat color.In conclusion, dietary GTP supplements of 4-6 g/kg increased host resistance to Haemonchus contortus infection by reducing worm burdens, furthermore, relieved the negative impact caused by Haemonchus contortus infection.