Non-traditional Forages in a Managed Grazing System for Control of Gastrointestinal Parasites in Sheep

Non-traditional Forages in a Managed Grazing System for Control of Gastrointestinal Parasites in Sheep

Summary

The first year of this two-year project was begun in the spring of 2009 and completed in late September of 2009. Chicory (cultivar: Forage Feast) was planted in May on all three farms, and brown mid-rib sorghum sudangrass (BMR) was planted in early June. Each forage was grazed for two, 2-3 week periods in 2009 and one was grazed only once as a result of a poor stand of chicory and the need to deworm all the project lambs. Annual weed competition in the chicory was a significant problem on two farms, and shortage of rainfall resulted in slow regrowth of forages on all farms. DrenchRite larval development assay results and fecal egg counts (FEC) revealed significant anthelmintic (dewormer) resistance profiles on two farms and reaffirmed resistance results obtained in 2007 on the third farm demonstrating resistance to all three chemical classes. Anthelmintic resistance and warm spring weather resulted in high FEC and significant parasitism in project lambs at the beginning of chicory/BMR grazing in July on two of the three farms.

The other farm, which has had previous experience with anthelmintic resistance and potentially useful grazing strategies, used a grazing strategy involving
a) a targeted selective treatment of about 70% of lactating ewes before turnout to grass in order to reduce pasture contamination
b) strip grazing of lactating ewes and lambs across permanent pastures, using a back fence to prevent access to feces contaminated pasture
c) movement to new ungrazed strips every 3-4 days to avoid newly developed L3 worm larvae
d) grazing weaned lambs on an alfalfa hayfield prior to grazing chicory/BMR.

This resulted in rather low FECs and low parasite loads in project lambs on that farm at the beginning of the first grazing period.

Statistical analysis of results will not be performed until the end of the second year of grazing, however, some observations from this first year can be made:

• Spring planting of chicory can be compromised by annual weed competition. We were aware of this potential but were not able to plant the previous fall because of project constraints.

• Both chicory and BMR can be good quality feed for sheep. BMR has a rapid growth rate and must be managed carefully to prevent the plants from becoming too mature resulting in lower feed quality. Staggered plantings might be useful.

• Two farms observed that in some areas in the chicory plantings lambs did not want to graze the chicory plants. The reason for this is not currently known.

• Compared to pilot work done in 2007, weight gains on chicory were not as good as expected. On two farms, weight change between the two treatment grazing periods suggested compensatory gains in the chicory group while on grass during that interim period. We speculated that this may have been related to lower chicory intake. Forage Feast has been shown to be less palatable than several other cultivars, including Puna from which Oasis was subsequently developed. Oasis was the cultivar used in the 2007 pilot work.

• FAMACHA© is a useful technique to identify anemic animals; however, weaned lambs are more difficult to score than ewes. This is not a new finding but was reinforced in this work and complemented by the finding of a few lambs with elevated FAMACHA© scores that did not have exceptionally high FEC. In some cases this seemed to be an animal characteristic.

• Body condition scores on young growing lambs on pasture tend to be rather uniform and average 2. This makes it a relatively insensitive outcome measure.

• FEC can be quite high in animals with acceptable FAMACHA scores.

Objectives/Performance Targets

Objectives for 2009 were met with the limitations specified in the summary. In 2010 we anticipate reduced parasite load for lambs at the two farms with higher burdens in 2009. This will be accomplished by selective deworming of ewes, strip grazing with short intervals, and selective deworming of some lambs before the chicory/BMR grazing begins. Forage analyses have been completed on the forages used in 2009.

Accomplishments/Milestones

Chicory stands were successfully established on the three farms and grazing groups of lambs as planned was successfully carried out. Sample collections were conducted and animal measurements were obtained as planned. All three farms have updated information about drug resistant parasites on their farms. This information is being used in planning strategies for 2010 to maintain acceptable levels of parasitism.

• Lambs grazing chicory at the Anderson farm 9-15-09
• Curt and Rory collecting forage samples 9-18-09
• Jeff McCutcheon collecting samples for chicory analysis 9-1-09
• FAMACHA score of 4 in lamb 9-15-09
• Lambs in brown mid-rib sorghum sudangrass – Cline farm 7-9-09

Impacts and Contributions/Outcomes

Fecal egg counting data, forage growth and quality information, selected grazing strategies, and images from 2009 have been used in four presentations on control of parasites in sheep and goats to veterinary (2) and producer (2) audiences. One of these was conducted by Mr. Cline and Mr. Lewandowski. Several more for spring 2009 are planned which will refer to selected experiences from this project. Our experiences in this and other projects are being used to develop additional proposals to conduct related work.

Collaborators: