Effect of a grazing sericea lespedeza as a treatment padock for controlling natural nematode infection in lambs

Effect of a grazing sericea lespedeza as a treatment padock for controlling natural nematode infection in lambs

Summary

Infection with gastrointestinal nematode parasites, particularly Haemonchus contortus is an important constraint to profitable small ruminant production in the southeastern US and worldwide. Anthelmintic drugs (dewormers) have been over-used in attempts to control this problem. Over use has resulted in high levels of resistance to dewormers where H. contortus is a problem. A more sustainable approach to parasite control involves integrating targeted, limited use of anthelmintics with non-chemical alternative control methods that reduce nematode numbers in the host animal and lower pasture contamination with eggs and larvae. This initial study evaluate the use of grazing Auburn Grazer sericea lespedeza (AUGSL), a condensed tannin containing forage, as a deworming paddock for mature ewes. Results showed that it took about 4 weeks for the ewes to acclimate to consuming enough AUGSL to have a reduction in FEC compared to the control ewes. This indicated that grazing AUGSL as a deworming paddock was beneficial and might be a potential alternative for nematode control.

Objectives/Performance Targets

Determine the effect of grazing sericea lespedeza, as a treatment (deworming) paddock, on gastrointestinal nematode infection in ewes/lambs.

Accomplishments/Milestones

The Auburn Grazer sericea lespedeza (AUGSL) pasture (1.5 acres) for this trial was planted in summer, 2007. The other 2 adjacent pastures were bermudagrass (1.5 acres each). AUGSL is a perennial forage that takes at least one year to establish for grazing purposes, therefore, the initial study was done in summer, 2008. The experimental conditions tested the effect of rotating mature ewes (not lambs as originally planned as not enough lambs were available) through the AUGSL pasture as a means to help control nematode infection over a summer grazing season. Twenty-seven naturally infected mature ewes were randomly allocated to 2 groups based on FEC. Group 1 (control) continuously grazed one of the 1.5 acre bermudagrass pastures (n=9). Group 2 was rotated between the AUGSL pasture and the other 1.5 acre bermudagrass pasture (n=18). The study period was 8 weeks. FEC and PCV were determined weekly to monitor infection level. No animals required deworming during the study. Residual feces from each treatment group were cultured for recovery, enumeration and identification of infective larvae (L3) to evaluate any change in the nematode population in animals during the study and also determine any effect of the AUGSL on larval development and survival in feces. Processing of samples was conducted in accordance with established procedures. FEC was equivalent (about 700 epg) at the start of the study and both groups decreased through 4 weeks when the FEC of control and AUGSL ewes was 144 and 482 epg, respectively. Subsequent to week 4, the control group increased and the AUGSL group decreased and at the end of the study the FECs were 580 and 94 epg, respectively. PCV remained similar through week 4 and subsequently, the control group remained realtively the same and the AUGSL group increased slightly (about 1.5%).
This first study indicated that it took about 4 weeks for the ewes to acclimate to consuming AUGSL as that was the time of the FEC switchover. The second study will be conducted in summer 2009 with lambs.

Impacts and Contributions/Outcomes

Results indicate that grazing AUGSL is a viable alternative for nematode control in ewes which will conserve and extend the useful life of available anthelmintics.

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