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ADVANCED PHYTOCHEMICAL SOLUTIONS FOR PREMIUM PRODUCTS

Project leader: Dr Lucy Meagher
Research organisation: AgResearch
Project number: 00AR55
Project number: 06 351 8100
Location: Palmerston North
Fax number: 06 351 8032
Email: lucy.meagher@agresearch.co.nz
Funders: Meat & Wool Innovation, AgResearch

Project outline: This research represents a sustained focus by AgResearch on linking the beneficial nutritional properties of condensed tannin (CT) containing forage legumes with the compounds responsible, and establishing their structure-activity relationship. The objectives of this research have been to develop antimicrobial bioassays against animal and human pathogenic bacteria, to complement existing intestinal parasite bioassays, so that bioactives from forage plants and pine bark can be isolated. Bioassay-directed fractionation of antimicrobial phenolics and CT has been coupled to recent acquisition of capabilities in liquid-chromatography mass-spectrometry (LC/MS) with electrospray-ionisation for identification of chemical constituents. Complete LC/MS analysis of fractions from Lotus corniculatus, Lotus pedunculatus, sulla and sainfoin prepared by Dr Yeap Foo from Industrial Research Limited, Lower Hutt has been linked to bioassay results, establishing structure-activity relationships. The development in the wider research programme of synthetic chemical techniques for the characterisation and sequencing of CT has enabled the classification of activity associated with distinctive chemical fingerprints.

The identification of bioactive components of CT-containing forage plants may provide leads with applications to animal health. Forage legumes contain a raft of unique phenolics and CT, and it has been possible to separate and identify some of those with dual activity in antimicrobial and antiparasitic bioassays. In addition to structural characterisation of CT bioactives, miniaturisation of existing parasite bioassays has enabled the identification of fractions containing another group of novel phenolics from forage that inhibit egg hatching and larval development of the sheep nematode, Trichostrongylus colubriformis.

Refer to Wool Grower Winter 2001 (issue #10, p. 17): 'Pining for an end to the superbug?' - Condensed tannins may hold the key; Winter 2001 (issue #10, p. 18): 'What are condensed tannins?'

DEVELOPMENT OF A DEFINED SUBUNIT VACCINE AGAINST JOHNE'S DISEASE

Project leader: Dr Alan Murray
Research organisation: Massey University
Project number: 98MN04
Project number: 06 350 5799
Location: Palmerston North
Fax number: 06 350 5636
Email: A.Murray@massey.ac.nz
Funders: Meat & Wool Innovation, Meat NZ

Johne's disease is a chronic wasting disease of sheep, cattle and deer caused by the bacterium Mycobacterium paratuberculosis. It is likely that the economic losses suffered by New Zealand farmers as a result of this disease, are in excess of $30 million per annum. An effective vaccine would greatly reduce these losses.

By studying the components of the bacterium and measuring their ability to modify the animal's immune response, a team at Massey University is paving the way to develop a vaccine that is safe to use and does not cause unacceptable lesions at the vaccine site.

Researchers are isolating the secreted proteins of the bacterium that the animal's immune system responds to during infection. Sheep have been vaccinated with bacterial components and it has been demonstrated that blood cells taken from these animals produce a 'protective type' of immune response. The blood cells from non-vaccinated animals do not respond to this material. The reactive proteins are being investigated further to assess their usefulness as components of a non-living (subunit) vaccine.

FOOTROT

A programme of footrot control including the following:
oPublication of 'A guide to the management of footrot' available from Meat & Wool Innovation (free to levy payers)
oAccreditation of specialist advisors

Refer to Wool Grower Autumn 2002 (issue #13, p.12): 'Giving footrot the boot' - New tools in the kit.

NOVEL JOHNE'S VACCINE

Project leader: Dr Colin Mackintosh
Research organisation: AgResearch
Project number: 98MN06
Phone number: 03 489 9229
Location: Invermay
Fax number: 03 489 9038
Email: colin.mackintosh@agresearch.co.nz
Funders: Meat & Wool Innovation, Meat NZ

Project outline: Johne's disease, which causes wasting and death in adult sheep, is estimated to be present on over 50% of sheep flocks in New Zealand, and to result in losses of well over $6 million annually. The vaccines currently available in New Zealand significantly reduce the incidence of Johne's disease, but can cause unacceptable lesions at the site of injection and in the shoulder lymph node. These side-effects may result in losses at slaughter due to carcass trimming. The lesions are a product-quality issue (i.e. look unpleasant) and neither the diseases, nor the vaccine, present a proven food-hygiene risk.

A modification of the vaccine has been developed by AgResearch and it is believed it will provide protection while avoiding the serious side-effects. A field trial, which started in 1998, is being undertaken to compare the efficacy of the new vaccination procedure with the existing vaccine. Because Johne's disease affects mostly adult sheep it has been necessary to conduct the trial for four years. During this time the trial has monitored the extent of subclinical Johne's infection, measured its effect on production, and assessed the ability of the vaccine to reduce losses in productivity.

Progress to date shows that vaccination with the novel vaccine causes minimal carcass damage compared with the traditional vaccine. Blood samples and skin tests taken during the first and second years after vaccination show that both vaccines are producing significant immune responses; this is a good indication that the vaccinated sheep should be better able to resist Johne's disease. A trial conducted last year showed that the cheek is not a suitable alternative site for vaccination with either the existing or the novel vaccine.

SHEEP LOUSE IMMUNOLOGY

Project leader: Dr Alex Pfeffer
Research organisation: AgResearch
Project number: 97AR39
Phone number: 04 922 1315
Location: Wallaceville
Fax number: 04 922 1380
Email: alex.pfeffer@agresearch.co.nz
Funders: Meat & Wool Innovation

Project outline: The objectives of this project are to use our increasing knowledge of the molecular biology of the louse Bovicola ovis, and of the sheep's immunological response to the parasite, in order to develop novel means to control louse infestation and reduce use of chemical insecticides.

Economic losses experienced by the New Zealand Sheep Industry because of the louse result largely from the costs of control and reduced quality of the fleece. These losses may be proportionally similar to the A$169 million annually attributed to the louse for the Australian Sheep Industry. In New Zealand, losses due to the pelt defect cockle, associated with louse infestation, amount to $10 to $15 million annually. This must also be included. Additional to the direct costs of infestation and treatment are market-related concerns over insecticide residues and developing resistance by the louse to commonly used insecticides.

A test that determines the level of louse infestation in flocks of sheep has been developed and is currently being prepared for use by farmers. This test will assist farmers to better manage louse infestation and chemical residues. On farms where louse infestation is well controlled, the test will be useful to confirm the status of the flock and allow the farmer to confidently reduce insecticide usage, thereby reducing treatment costs and wool residues. Where louse infestation is not well controlled, the test can be used to detect the problem early so that appropriate treatments can be instituted before wool is damaged, and well before shearing. Knowledge of the levels of louse infestation in flocks through use of the test will assist farmers to streamline louse treatment practices, to achieve maximal effectiveness and economy.

Refer to Wool Grower Autumn 2002 (issue #13, p. 7): 'New louse test ready for action' - A new test, which will give farmers early warning of a louse infestation, is now ready for use; Spring 2001 (issue # 11, p. 13): 'Checking for lice like a pregnancy test'; Winter 1999 (issue #3, p. 13): 'Vaccine for lice?' - From sheep antibodies (research story); Summer 1998 (issue #1, p. 25): 'Fine and mid-micron wool' - Don't louse it up!

WINTER WOOL GROWTH

Project leader: Dr Allan J Pearson
Research organisation: AgResearch and Massey University
Project number: 98AR29
Phone number: 07 838 5197
Location: Ruakura
Fax number: 07 838 5536
Email: allan.pearsona@agresearch.co.nz
Funders: Meat & Wool Innovation, AgResearch, Massey University, FRST

Project outline: In ewes, reduced winter wool growth is due to the combined influences of pregnancy, reduced feed intake, and the physiological effects of short days. The result is reduced productivity and wool strength. The goal of this project is to develop and field-test protocols for the modification of circulating hormones during critical periods of wool growth in spring-lambing ewes. Alternatively, new sheep genotypes resistant to photoperiod-induced changes in wool growth could be developed with the knowledge generated by this project.

Increasing winter wool growth will improve not only the ability of producers to supply wool to specification, but also management flexibility. The industry goals are:

" a 20% increase in annual fleece production
(up to 1 kg/head)
" an improvement in staple strength of 5-10 N/mm2.

Initial trials defined the timing of changes in monthly wool growth over winter in dry and pregnant/lactating sheep fed to maintain maternal body-weight. Changes in wool growth rate have been related to changes in hormonal profiles, wool characteristics (diameter and length growth rate, strength and bulk) and wool sulphur content. In recent experiments winter wool production has been modified by directly altering hormonal profiles. Changes in gene expression in the skin as a result of these treatments are being measured and used to develop an optimal protocol for on-farm use.

Refer to Wool Grower Autumn 1999 (issue #2, p. 20): 'Winter wool at summer growth rates?'

 

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