A Newsletter of the Sheep Meat Group of the WA Department of Agriculture December 2001 Number 17

Editor: Dr Sarah Wiese Ph: 08 9885 9070 Fax: 08 9885 9060 Email: twiese@treko.net.au

When muscle sugar levels are low at the time of slaughter the pH of meat is high and the meat is dark cutting. Dark cutting meat is less attractive to consumers for several reasons. Not only is the meat a dark, unattractive colour but it also tends to be tougher, take longer to cook, and have poorer keeping qualities and flavour.

In a recent study of 10 consignments of lamb the incidence of dark cutting varied considerably between 0% in one line to 56% in another. The overall incidence of dark cutting was 17%. So what was different between the lines with a high incidence of dark cutting and those with a low incidence?

A major factor was the amount of sugar present in the muscles when the lambs left the farm. Age was also important with more dark cutting in sucker lambs than carry over lambs. Transport and lairage had less of an impact on dark cutting than muscle sugar or age however, they were more important for sucker lambs than carry over lambs. Both very short lairage periods (ie slaughtered straight off the truck) and long lairage periods (48 hours in lairage) tended to increase the incidence of dark cutting in sucker lambs.

There was some evidence of stress in sucker lambs during transport. More investigation is required to determine the nature of this effect on sucker lambs. In the meantime there are some on farm factors that clearly can influence the incidence of dark cutting in all age groups of sheep.

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Dark cutting in lamb 1

Measuring sheepmeat eating quality using 2

consumer taste panels

MLA National Sheepmeat Eating Quality 3

Program trial results

Case study: A simple feedlot at Kellerberin 5

Arthritis in carryover lambs 6

Alternative sheep breeds demonstration 7

Annual ryegrass toxicity (ARGT) 10

Esperance ewe productivity trial 10

Contact list 12

In this edition .........

DISCLAIMER

Mention of trade names does not imply endorsement or

preference of any companies by the Department of Agriculture,

and any ommission of a trade name is unintended. Any

recommendations are correct at time of printing.

Dark cutting in lamb

Robin Jacob Division of Veterinary and Biomedical Studies, Murdoch University

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On farm tips to prevent dark cutting in lamb

Diet has a big impact on muscle sugar. Muscle sugar will increase just 7-14 days after changing from low to high-energy diets. For lambs finished on low quality pasture, feeding a high-energy supplement for a minimum of 7 days prior to slaughter will help to avoid dark cutting.

Nutrition may also be the reason for sucker lambs being more at risk of dark cutting. In the recent study pastures were haying off so the nutrition of the lambs was on the decline despite still being on the ewes. These lambs subsequently had low muscle sugar levels.

Take care during mustering, as exertion will cause lambs to use up stored muscle sugar. If lambs are a long distance from yards bring them closer to the yards and allow them time to recover from the long drive before being consigned to slaughter. Feeding for 7 to 14 days close to the yards will maximise the value of feeding high energy supplements before slaughter.

Condition score is generally not associated with dark cutting. Lambs in good condition can still have low muscle glycogen if stressed, exercised or if their feed is on the decline prior to slaughter.

Merinos are more susceptible to stress than crossbred lambs. However Merinos will achieve high muscle sugar levels and no dark cutting if fed and treated appropriately.

Take care when shearing before slaughter if the weather is cold. Shearing increases the energy requirements of sheep during cold weather for four weeks after shearing. Cold stress will reduce muscle sugar but this can be overcome by feeding high energy diets during the four week period post-shearing.

Keep in touch with your abattoir and ask for any feedback on your lambs.

What is ‘eating quality’ in lamb and sheepmeat and how do we most accurately and cost effectively measure it?

‘Eating quality’ means different things to different people – for some it is meat colour or pH, for some an objective measurement of tenderness such as shear force, or the use of trained or untrained taste panels. All of these mechanisms are measures of meat quality that attempt to estimate the satisfaction of consumers eating the meat.

Untrained, consumer taste panels are the closest we have to “the real thing” in terms of assessing the eating quality of lamb and sheepmeat products. Consequently, consumer taste testing is increasingly used to measure consumer acceptance of meat eating quality. By rigorously following a defined protocol for the taste tests, extraneous variation can be removed, and test results create meaningful data on eating quality and variability which can be analysed statistically.

The word consumer means people selected from the community with the only requirement that they are between 20-50 years old and eat sheepmeat at least once every two weeks. For any meat sample ten consumers give their opinion of the eating quality attributes.

The tasters score each meat sample by marking a line in five categories – liking of odour, tenderness, juiciness, liking of flavour, and overall liking. The mark on the line is translated into a score out of 100 by measuring its position.

The consumer is then asked to give an 'overall rating'

for the product consumed by ticking one box only e.g.

Awful

Unsatisfactory

Good every day

Better than every day

Premium

Each consumer in the taste panel is presented with samples to taste in a different order so that the comparison of one sample to another does not bias the test. Prior to the start of the test a uniform midrange sample is served so that the tasters are all starting from the same benchmark.

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Measuring sheepmeat eating quality using

consumer taste panels Alex Hollick Department of Agriculture, Narrogin Dr David Pethick Division of Veterinary and Biomedical Sciences, Murdoch University

preliminary way the results of the research thus far.

Figure 1. Critical control points for the consumer acceptance of sheepmeatMeasurement of sheepmeat eating quality The measurement of eating quality in this program has been based on consumer taste panels. Untrained consumers give product a score out of 100 for the following attributes: liking of odour, tenderness, liking

of flavour, juiciness and overall liking. The consumer is then asked to give an 'overall rating' for the product consumed by selecting one of the following; awful, unsatisfactory, good every day, better than every day or premium.

Preliminary modelling has found the best estimate of the 'overall rating' given by the consumers is: tenderness x 0.2 liking of flavour x 0.3 juiciness x 0.1 overall liking x 0.4

This gives the sheep meat consumer score which ranges from 0-100. An interesting finding was that flavour was a positive attribute of sheepmeat and was weighted more heavily than for beef. The above weightings are flexible and can and will change with time for different scenarios. The most important feature is that the program can identify for example tenderness or flavour, depending on the requirements of industry.

Effect of cut Most of the previous work in sheepmeats has concentrated on understanding the eating quality of the loin since this muscle is both easy to use and prepare, and is a high value cut. However, the message from industry was to also investigate other cuts in the fore

Samples can be cooked either by grilling or roasting. In all cases, the cuts are reduced to the main muscle, and all fat, connective tissue, silverskin and gristle is removed.

Grilling samples have a slice thickness of 15 mm, and range from 50 to 70 mm in diameter, with a ‘normal’ diameter of 60 mm. Roasting samples are fabricated into roasting blocks of 150 x 75 x 75 mm. Where individual muscles are too small to achieve this, the respective matched muscles from both sides of the carcass are faced together to attain a roasting block of the required size.

Consumer sensory testing is thus a highly scientific process producing meaningful data for improving the quality of meat the consumer receives.

The sheepmeat eating quality program was set up by Meat and Livestock Australia at the direction of Sheepmeat Council. Initially a large consultation process across all industry sectors identified a number

of critical control points which might impact the eating quality of sheepmeats (Figure 1). This consultation has guided the development of the research program and the design of the experiments.

The primary aim of the program is to be able to predict the eating quality of sheepmeat, based on a knowledge of how the meat was produced and processed. This will identify those factors which can be used by commercial sheepmeat supply chains to improve quality.

The program is a little over half way and already it is clear that by using consumers in controlled sheepmeat tasting sessions it is possible to define the eating quality of sheepmeats. The program has already defined many factors both pre and post farm gate which are important in determining the eating quality of sheepmeats. Below we have outlined in a

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MLA National Sheepmeat Eating Quality

Program trial results

Dr David Pethick National Coordinator Sheepmeat Eating Quality Program, Meat and Livestock Australia Division of Veterinary and Biomedical Sciences, Murdoch University

Consumer

Conception Pre-slaughter control

Post-slaughter control

Genetics

Sheep age (lamb, mutton)

Growth path (feed type & finishing)

Pre-slaughter stress

Hang

Cold/heat shortening

Aging of meat

Retail cuts

Value adding

Cooking

with little difference between cuts. The loin declined less in consumer score when comparing lamb versus mutton than the hind or fore quarter cuts. Perhaps surprising however, is that all the mutton cuts were still rated as good every day eating by consumers (approximate cut off is 50 points).

Effect of animal age In a follow up experiment, animal age was looked at more closely. Merino’s spanning carry over lamb (9 months old) to older mutton (5 years) were sourced from a commercial farm and placed on a nutritionally balanced feedlot pellet on farm (5 weeks for the lambs, 2-3 weeks for the hogget and mutton). The change in consumer score of the loin (LD) and outside (BF) with animal age is shown in Figure 4.

There was little difference in the consumer score of the loin between hogget and lamb but the consumer score then declined by some 6-8 points as ewes progressed to 8 teeth (4 years and older). Lamb and hogget loins were rated as better than every day while the mutton loins (4 through 8 teeth – 3-5 years old) still rated as acceptable.

A similar response was seen for the outside (BF) although the magnitude of the decline was greater at 9-11 points. The main driver for the effects of animal age on the consumer score was the tenderness rating – that is the data did not suggest any rejection of the older product due to a dislike of flavour.

Figure 4. Consumer scores of loin (LD) and outside (BF) muscles from Merino ewes ranging in age from lamb to 5 year old mutton.

Processing and aging of meat Modern processing requires high throughput and strong chilling of carcases in order to maximise both profitability and carcase hygiene. This scenario can lead to cold shortened sheepmeat - when muscles on the carcase strongly contract and become tough due to very cold chilling soon after dressing.

One approach to strong chilling and cold shortening is electrical stimulation which was developed in New

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and hind quarter.

In the first experiment consumers ranked the loin (LD), outside (BF), rump (GM), topside (SM) and chuck (SV) muscles from grilled first cross lamb (26.7 kg HCW, 13.9 mm GR, 10 months old).

There was a large difference between the best cut (loin) and worst cut (topside) of around 25 consumer points based on a score out of 100 (Figure 2). However, with the exception of the topside, most of the lamb carcase was rated either ‘good every day’ or much better.

Figure 2. Consumer scores for different cuts from grilled carry over lamb. (LD = loin; BF = outside; GM = rump; SM = topside; SV = chuck).

Effect of cut x animal age The effect of animal age on the consumer rating for the grilled loin (LD), outside (BF) and chuck (SV) muscles were compared in young lambs (2nd cross, 21 kg HCW, 12 mm GR, 5.5 months old) with wether mutton (Merino 31.6 kg HCW, 16 mm GR, 4 years old).

Figure 3. The effect of animal age (5.5 month old lamb versus 4 year old wether) on consumer acceptability of 3 cuts. (LD = loin; BF = outside; SV = chuck).

All the lamb cuts rated better than every day quality

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taking effect as animals become older. The effect of animal age is around 5-12 consumer points depending upon the cut.

• Processing – correct processing of sheep is critical to ensure the product reaches its ‘true’ potential. Processing conditions which avoid cold shortening will improve the product by about 10 consumer points.

• Hang – tenderstretch improves the loin by about 5 consumer points and should have a bigger effect in the hindquarter cuts.

• Aging – aging the product from 2 to 5 days improves the consumer score by 7 points with little further improvement by aging to 14 days.

It is too early to develop a model for the prediction of sheepmeat eating quality, but given the results thus far we are very confident that the program will deliver the tools necessary for assessing the eating quality of sheepmeat.

AcknowledgmentsThe author acknowledges the dedicated and cooperative effort of the National Sheepmeat Eating Quality team involving people from Meat & Livestock Australia, Cosign, Departments of Agriculture in WA, Vic. and NSW and, the University of New England and Murdoch University. The valued cooperation of the Australian Sheepmeat Industry is also gratefully acknowledged.

Sheep feedlots do not necessarily have to be purpose built, nor do sheep need to be fed expensive rations. Kit Leake, of Nanyanine Livestock, Kellerberrin, regularly feedlots his cull Merino ewe weaners in autumn using a simple facility and home-grown, low cost feed. He converts sheep that have a very low value into prime lambs for which there is a ready market. Consistently each year, over 6 to 8 weeks, he more than doubles his money by feedlotting lambs.

Feedlotting usually begins in mid April, but can start as early as February, if lupin stubbles have run out. A small, shaded paddock near the grain silos was chosen for the feedlot site. No hay or grain feeders were used and the only work required was to install a water

Zealand many years ago to improve the quality of frozen lamb being shipped to the Northern Hemisphere. Recent testing of electrical stimulation has shown that electrical stimulation consistently produces an increased consumer score of 6-10 points depending on the cut. Most importantly it helps to remove ‘tough’ animals even after only 2-3 days aging.

Another old fashioned approach is to tenderstretch hang carcasses as they enter rigor mortis. Tenderstretch puts tension on the loin and hind quarter muscles and so physically stops them from contracting and becoming tough. In Figure 5 the effects of tenderstretch and meat aging are described. Tenderstretch results in a 5 point improvement in consumer score at any period of product aging.

Product aging was also highly effective in increasing the consumer score by an average of about 7 consumer points for both lamb and mutton. The improvement due to aging was largely complete by day five.

Figure 5. The effect of aging on the loin of lambs hung conventionally (AT) or tenderstretched (TS).

ConclusionsThe factors and their effects on sheepmeat eating quality that have so far been identified are:

• Cut – the effect of cut is large at 25 points. However with the exception of the topside there is a relatively smaller effect of cut in lamb such that most perform as ‘better than every day quality’ given optimal processing.

• Animal age – the effect of animal age is minor for the carryover lamb to hogget transition but starts

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Case study – A simple feedlot at

Kellerberrin

Roy Butler Department of Agriculture, Merredin

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Arthritis is a very common problem in West Australian flocks and costs the national sheep meat industry millions of dollars in loss of production and sometimes death on farm, or condemnation of carcases at abattoirs.

This year in Western Australia, processors recorded particularly high incidences of arthritis in carry over lambs (delivered in Feb, March and April) compared to the new season lambs, resulting in downgrading or condemnation of affected carcases.

What is arthritis and how can you prevent it? Arthritis in lambs and weaners is caused by bacteria (in WA this is usually a bacteria called Erysipelothrixinsidiosa) which enters the lambs body through a break in the skin, usually a cut made at mulesing or shearing. The bacteria travel in the bloodstream to the joints, where they multiply and cause damage. Within a couple of days, lambs are reluctant to move and are quite lame. The infected joints are painful, hot to the touch and swollen. Arthritis is usually noticeable in the knees of the front legs and/or the stifle of the back legs.

Most cases of arthritis persist to the chronic stage, where lameness and stiffening of the limbs result in stunted growth, decreased wool production and sometimes death.

The Erysipelothrix bacteria can live in the soil for long periods of time. Permanent sheep yards, feedlots and sheep camps are the most heavily contaminated areas on a farm.

Treatment Usually by the time the sheep are noticeably lame, treatment is too late to have a chance of success. If arthritis is diagnosed early, treatment with antibiotics may produce reasonable results but this is usually uneconomical with flock sheep.

Prevention and Control To control arthritis effectively, producers need to know when lambs are picking up the bacteria – whether at birth, marking, shearing or in the feedlot. They then need to either take measures to prevent lambs coming into contact with the bacteria (by using temporary yards on well grassed areas and by thoroughly sterilising/disinfecting instruments at mulesing) or stop arthritis affecting lambs by implementing an effective vaccination program.

With the current lamb prices, vaccination at approximately 60 cents/lamb (two doses of 1 ml at 0.30c) is well worth while. Ewes can be vaccinated prior to lambing and lambs then vaccinated at marking, or lambs can be vaccinated at mulesing with a booster four to six weeks later (at weaning). The

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trough. Faba bean seconds and large round bales of frosted wheaten hay, both from the previous season, were fed ad lib on an exposed rock.

Although the grain had a low value, it was of good quality relative to the needs of young sheep. It contained approximately 65% faba beans, plus wheat, ryegrass, radish, lupins and wild oats. A representative sample was tested at 19.0% crude protein and 10.8% MJ/kg. The hay was not tested.

The sheep ate an average of 1.3 kg total feed per day, comprising approximately 75% grain and 25% hay. Over 44 days the average weight of 174 ewe weaners rose from 32 to 37 kg. Up to shearing, midway through the feeding period, they gained weight at an average of 250 g/h/d. No health problems were experienced.

The total feed cost, not including labour, was estimated at 14 cents per head per day. The grain seconds were valued at $100/t and the hay at $40/bale (400 kg bale, 5% wastage).

On March 21, forty-four days after feeding began, 102 of the 174 lambs were slaughtered at Linley Valley abattoir. Selection for slaughter was on the basis of liveweight, on the previous day, of at least 37 kg. All carcasses had fat scores of 2 or 3, and 74 (73%) of the carcasses weighed more than 16 kg.

In this case-study, all the ewes, regardless of weight, went into the feedlot when the paddock feed ran out earlier than expected. Kit pointed out the problem posed by low body weight lambs in a feedlot. They simply cannot grow fast enough to make the first draft, although they will cost as much to feed over that period as those that do.

Ideally, farmers should set a minimum weight for sheep entering a feedlot, taking feed cost, consumption and likely weight gain into account.

Arthritis in carryover lambs

Eliza Dowling Sheepmeat Product Development Officer, Narrogin

Kit Leake at “Nanyanine” in Kellerberrin

wool and has good growth rates.

Finn: The Finn is a dual purpose breed originating in Finland. They are extremely fertile and produce medium grade wool. A steady increase in registration numbers attest to the breed’s acceptance and viable place in the industry.

South African Meat Merino: The South African Meat Merino (SAMM) is a dual purpose breed bred specifically to produce a slaughter lamb at an early age (35 kg in approx 100 days). They produce good volumes of medium strong wool and commonly have high lambing percentages.

Texel: The Texel is well known for its lean, well muscled meat. They produce low grade wool and are the dominant terminal sire breed in Europe.

Dorper: The Dorper was primarily bred for mutton production. Dorpers are well known for their fertility and also their ability to survive under harsh conditions. The Dorper’s skin covering which is a mix of hair and wool, will drop off if not shorn to keep it tidy. The skin is thick and is the most sought after sheep skin in the world.

Damara: The Damara originates from East Asia and Egypt but is now the dominant breed in the harsh environments of Namibia and Angola. They are bred to survive harsh environments, are exceptionally vigorous and can reproduce where food and water is limited. There is a strong export market for Damara meat into the Middle East but at this stage there is no domestic market in Australia.

Merino: Merino rams from the ‘Kardella Stud’ in Moora were used in the trial.

Poll Dorset: Poll Dorset rams from the ‘Lockier River’ stud in Mingenew were used in the trial.

Table 1. Breeds and breeders

important thing is to recognise when lambs are picking up the arthritis bacteria and plan your vaccination accordingly.

If your carryover lambs showed signs of arthritis or processors picked up the problem in your lambs earlier this year, beware!

• Check your lambs for arthritis prior to putting into the feedlot. Arthritic lambs will not thrive and will cost you money.

• Keep a record of when your lambs show signs of arthritis and take preventative measures or plan an effective vaccination program for next year.

• If you think your lambs might be carrying the bacteria, take care when shearing and allow two weeks for shearing cuts to heal before introducing sheep to a feedlot.

Please note; arthritis was not the only chronic condition recorded in carryover lambs. The incidence of cheesy gland (CLA) was also much higher in carryover than in sucker/new season lambs.

With variable grain prices, the recognition of unviable cropping land and most prominently herbicide resistance, there is a strong requirement for many farm businesses in the northern wheatbelt to re introduce or further develop livestock enterprises. Because of this renewed interest and because many producers are near enough to starting from scratch, producers are looking at ‘alternative’ sheep breeds as a means of making livestock profitable. One of the problems with making such a decision is the lack of locally generated information and also independent comparisons across the wide range of breeds available.

A demonstration has been established on Carl and Rachelle Forward’s property in Mingenew to provide some information and comparisons on the performance of alternative sheep breeds in the northern wheatbelt. Eight breeds have been included, four terminal sires and four dual purpose breeds. The breeds involved are;

Dohne: The Dohne is a German mutton sheep originating from a Peppin Merino and German Mutton Merino which was developed in South Africa. They are a fertile, dual purpose animal which produces fine

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Alternative sheep breeds demonstration

Cameron Weeks and Erin Hasson Mingenew-Irwin Group Inc.

Breed Breeder Location

Dohne Gerald, Carine & Justin Chick Northampton

Finn Fred Wilkinson Mundaring

SAMM Leonie Box Northampton

Merino Stephen Bullock Moora

Dorset Peter & Belinda Horwood Mingenew

Texel Rob & Maria Wood Bindi Bindi

Dorper Peter Batten Yuna

Damara Darren Forrester Yuna

• It was hard to identify the Finns and Dorsets at this early stage.

• The Texel lamb’s dark extremities and white faces were noticeable against the Merinos.

Table 2. Number of lambs marked and lambing percentage for each breed.

Liveweights and growth rates The lambs were weighed on the 4th July and again on the 16th August. The Dorset lambs had the fastest growth rate followed by the SAMM and then the Finn lambs. The Merino lambs had the slowest growth rate but still had virtually the same average weight by the 16th August as the Damara, Dohne and Finn lambs. The Texel lambs were the heaviest on the 16th August closely followed by the SAMM lambs.

Incidence of fly strike In the week leading up to the 7th August there were four very wet days. During this time seven Merinos, ten Dohnes, one Dorper and four SAMMs became fly struck. The Merinos, Dohnes and SAMMs were treated but the Dorper did not need treating. Three Merinos, three Dohnes, one SAMM and one Texel died from fly strike during this time.

Demonstration protocol Four hundred and sixty Merino ewes belonging to the Forward’s were drafted into eight separate mobs in November 2000. Mobs were made as uniform as possible. The dual purpose breeds (Dohnes, Merinos, SAMMs and Finns) were each mated with 80 ewes. The other four breeds (Dorsets, Dorpers, Damaras and Texels) were each mated with 35 ewes as they are bred for their meat only.

The ewes were mated between the 7th November and the 19th December. Some mobs were kept on Forward’s farm whilst others were run on neighbouring properties. Each breed had only one ram per mob except for the Merinos that had two rams in the mob. The reason for this being their rams were unprepared, as they had just been used for AI.

After mating, for ease of management on Forward’s farm, the ewes were run in four separate mobs of Dohne and Dorper, Dorset and Finn, Texel and Merino, Damara and SAMM. Lambs dropped between the start of April and mid May.

Lambing percentageThe lambs were marked on the 18th May, lambing percentages were calculated and all breeds were put back into one mob. The number of lambs and marking percentages are given in Table 2.

A few observations were noted as the lambs were marked:

• Dohne and Dorper lambs were very solid and healthy looking.

• Dorpers were very lively in the cradle.

• SAMM lambs were also very healthy and quite long in the body.

• Damara lambs looked to be doing well.

• Finn lambs seemed smaller and perhaps younger than the other breeds.

• The Finns and Dorsets may not have been on as good a feed as the other mobs (wheat stubble instead of lupin stubble which other mobs were on) although they were fed lupins and hay during the lambing period.

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Breed Number of ewes

Number of lambs

Lambing percentage

Dohne 80 86 107.5%

Merino 80 67 83.7%

Finn 80 55 68.7%

SAMM 80 41 51.2%

Dorper 35 34 97.1%

Damara 35 33 94.3%

Texel 35 29 82.9%

Dorset 35 24 68.6%

Dorper Damara Texel Dorset SAMM Dohne Finn Merino

Weight – 4 Jul (kg) 24.4 21.1 26.9 20.8 25 21.4 19.9 21.6

Weight – 16 Aug (kg) 32.8 29.1 35.3 30.8 34.4 29.1 28.7 28.8

Total weight gain (kg) 8.4 8 8.4 10 9.4 7.7 8.8 7.2

Growth rate (g/day) 195 186 195 233 219 179 205 167

No. lambs weighed 30 34 27 22 38 83 58 60

No. lambs < 30 kg 9 18 2 9 7 48 41 38

No. 37 kg or above (33 kg for Damara)

7 6 10 4 15 6 2 1

Table 3. Average liveweight and growth rate of the eight breed groups in the trial

length and were all high score 3’s.

Dohne & Merino: shallow backs with minimal fat on the shoulders and lots of bruising, very average lambs.

Dorset: confirmation average, meat colour and fat were good, good smaller type lambs.

Finn: confirmation similar to Dohne, colour and fat okay, hard to comment on only two lambs but they were only average lambs.

Wool evaluations A wool sample was taken from no less than 10 lambs of each of the Merino, Dohne, SAMM and Finn breeds. The results are shown in Table 5. There was only 1.3 micron difference in fibre diameter between the Merinos which were the finest and the Finns which were the broadest. The Finns had the lowest curvature and the SAMMs the highest curvature. There was little difference in the comfort factors with all breeds having relatively good measurements.

Table 5. Wool micron, curvature and comfort factor for wool samples from the Merino, Dohne, SAMM and Finn first cross lambs

AcknowledgementsA huge thank you to Carl and Rachelle Froward for hosting the trial. It has taken greater effort and commitment than most Mingenew Irwin Group trials. Thank you also to Mark Mahney, Elders Mingenew who has helped and supported the trial, and Matthew Young, Department of Agricullture, Geraldton, V & V Walsh, Bunbury and Fred Wilkinson who have provided assistance. Thank you also to the breeders who provided rams and enabled the demonstration to take place.

Slaughter of the first consignment The first draft of lambs were slaughtered on the 23rd

August at V & V Walsh, Bunbury. The number of lambs slaughtered, their average carcase weights and average prices are shown in Table 4. No Damara lambs were slaughtered. V & V Walsh would not normally take Dohnes, Finns and Merinos. They agreed to accept them so that all the carcases could be evaluated, but prices may not be a true representation of the normal market value.

Table 4. Number of lambs slaughtered and the average carcase weights and prices for each breed

SkinsV & V Walsh consider a skin to be premium when it has light to medium rib, good length and a large area (18 kg + carcase required for the area). The SAMM, Dorset and Dohne were considered to have premium skins. The Texel skins had a high area but light rib, the Merino skins had heavy rib and small areas, the Finn skins had light to heavy rib and an average area and due to being coloured the Dorper skins were classified as special market skins only.

Processor comments V & V Walsh prefer lambs which are 18-22 kg and high score 2 to low score 3. V & V Walsh rated the Dorpers, SAMMs and Texels as the best lambs in the consignment and made the following comments on each breed:

Dorper: best lambs in the trial, mostly high score 2’s to low score 3’s.

SAMM: good confirmation, bright meat and fat colour, fat coverage improved with carcase weight, excellent 18 kg + lamb.

Texel: strong confirmation 18 kg lamb, bright meat and fat colour, in general the carcases were shorter in

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Or Eric Patterson Ph: 9822 8013

PO Box 657 Katanning WA 6317

Breeding the ‘Balanced Merino’ by reducing micron and improving

comfort factor while maintaining body weight, size and wool cut.

Breed Number of lambs

Carcase weight (kg)

Price($/kg)

Value per head ($)

SAMM 11 19.3 3.50 67.4

Merino 5 18.7 3.47 64.7

Dorset 6 17.4 3.47 60.5

Finn 2 19.7 3.50 68.8

Dorper 8 19.4 3.50 67.8

Texel 14 18.1 3.50 63.5

Dohne 7 18.6 3.50 65.1

Merino Dohne SAMM Finn

Average micron

19.9 20.3 20.7 21.1

Micronrange

17.0-22.0 16.1-22.7 18.2-22.6 19.7-22.5

Average curvature

80.4 83.0 90.5 74.5

Curvature range

76-83 63-103 77-103 57-93

Average comfort factor

98.4 97.3 98.6 96.7

Comfort factor range

96-99.9 95-99.7 96-99.9 90-99.1

preference to other grains.

Animals can continue to go down for up to 10 days after being moved off the toxic paddock (with peak deaths often occurring at four days). Animals showing intermittent convulsions will often recover once the source of toxin is removed but if animals are down for long periods they require considerable care and are difficult to save.

Once a paddock becomes toxic it will remain so. Toxic ryegrass seed heads stored in hay or cocky chaff remain toxic for years. However, as summer progresses and the ryegrass dries off, more galls are shed on to the ground where they are less likely to be eaten. Early autumn grazing of paddocks which were only slightly toxic is possible but should be treated with caution and stock monitored carefully.

Older sheep rather than weaners should be used to graze high risk paddocks. Older sheep will be able to tolerate a higher dose of the toxin before showing signs than young sheep as the toxin is cumulative and reaches a lethal dose on a per kilogram liveweight basis.

Research results have shown that sheep with a low or margional vitamin B12 status succumb to ARGT more quickly. Ensuring sheep have been treated with cobalt or vitamin B12 before grazing slightly toxic paddocks may help sheep to tolerate low levels of the ARGT toxin. However, if the challenge from the toxin is high enough, cobalt or vitamin B12 will not prevent deaths.

For long term control toxic paddocks can be treated with the twist fungus, which inhibits the development of the nematode and bacterium. See Farmnote 33/98 from any office of AGWEST.

For short term prevention on known toxic paddocks farmers can spraytop – graze or mow within 10 days of first flower head emergence. Alternatively chemical hay freezing can be done to conserve the nutritional value of pasture. All three procedures pre-empt seed set and so control development of toxicity.

The aim of a ewe productivity trial is to allow farmers to benchmark the ewe component of their flock, by collecting measurements to do with wool and lamb production. The Esperance ewe productivity trial is being run over two years, the first year looking at growth rates and wool characteristics of the ewes and the second year measuring wool and lamb production. All the teams are run together at the same site and are exposed to the same environment and management conditions.

At the beginning of 2000, six teams of twenty blue tag 1999 drop weaner ewes, were entered into the Esperance ewe productivity trial.

Team 1 First cross Poll Dorset X Merino

Team 2 First cross South African Meat Merino X

This season is turning out to be quite a bad season for annual ryegrass toxicity with outbreaks reported in several areas that have not had a problem for several years and in areas once considered west of the high risk area.

Annual ryegrass toxicity is a fatal disease killing sheep, cattle and horses grazing infected ryegrass. Ryegrass becomes infected when a nematode, Anguina funesta, carries the bacterium, Clavibactertoxicus, into the maturing seed head of ryegrass. The seed head is then replaced by a toxic yellow bacterial gall.

The combination of seasonal factors which leads to a high number of ryegrass seed heads being infected by the nematode, these nematodes carrying live and active bacteria and the bacterium turning on their toxin producing systems is still not well understood. However the requirement for all of these factors to be in place may explain why the problem appears to be worse in some years than others.

Outbreaks this year have frequently occurred following a rainfall event. This is most likely to be due to the grazing behaviour of stock. Stock tend not to graze while it is raining, and so are both hungry and have an empty gut when it stops raining. At the same time the wet leaf material is less appealing and stock are more likely to select seed heads. This results in the stock ingesting material with a higher concentration of toxin into an empty gut which then enables the rapid absorption of the toxin.

Symptoms of ARGT may appear as soon as 48 hours or as late as several weeks after animals are introduced to toxic paddocks. Stock grazing paddocks containing annual ryegrass in districts where losses have been reported should be inspected at least once daily to minimise losses. Be particularly careful to inspect stock following rainfall events, even if stock appear to have been grazing safely on that paddock for some time, as the rainfall event may be the trigger which makes ARGT show up.

Signs of ARGT are stimulated by stress or activity, so when inspecting mobs they should be stirred up and driven briskly for 100 to 200 metres. Animals affected by ARGT will fall behind the mob, show an unco-ordinated gait, stop and usually fall over. They will convulse, typically throwing the head back with stiff legs. Many animals fall down and convulse for 15 seconds to 3 minutes before they appear to recover and rejoin the mob.

When affected animals are found the mob should be moved quietly to a ‘safe’ paddock with good water, safe feed and shade. Avoid high protein feeds such as lupins as the toxin involved with ARGT damages the liver and makes the animal unable to deal with high levels of protein. Good quality hay is best or oats in

10

Esperance ewe productivity trial

Kira Buttler Department of Agriculture, Esperance

Annual ryegrass toxicity (ARGT)

Dr Sarah Wiese, ‘Chuckem’, Highbury

September 2000 and the increased demand of lactation caused a set back in their liveweight and growth rate in September. Despite this setback, their final liveweight of 57.6 kg was still significantly heavier than the other five teams.

All teams began to lose liveweight once the pasture hayed off in November. The three Merino teams numbered 3, 4 and 6 were the lightest at the end of the sampling period, with Team 6 – the Merinotech bloodline being significantly lighter than the other five teams, with an average liveweight of 48.8 kg.

Figure 2. Average liveweight change of teams in the Esperance ewe productivity trial

Figure 3. Change in average condition score of teams in the Esperance ewe productivity trial

Merino

Team 3 Merino – Esperdel Bloodline

Team 4 Merino – Cranmore Bloodline

Team 5 First cross Border Leicester X Merino

Team 6 Merino – Merinotech Bloodline

The ewes were entered as weaners ranging in age from 8 months to 12 months of age. To overcome different environmental backgrounds, the even-up shearing was delayed until the 9th of June which was four weeks after the intake of the last team. Immediately after the even-up shearing the ewes were weighed, and this marked the beginning of the trial.

Growth Rates Liveweights and condition scores were collected at 4 to 9 week intervals from off shears on the 9th of June 2000, through to the 7th of February 2001 (see Figures 1-3). Average team liveweight is presented in Figure 1, the changes in liveweight in Figure 2, and the average condition score in Figure 3.

Figure 1. Average liveweight of teams in the Esperance ewe productivity trial

Team number 5 - the first cross Border Leicesters, started in the trial with the heaviest liveweight and gained weight most quickly during the first month. Unfortunately a ram jumped the fence into the ewes paddock and mated approximately half of the first cross Border Leicester ewes. They lambed during

Rank Team Breed or bloodline Micron (μm) Yield (%) GFW (kg) Clean ($/kg) Value ($)

1 4 Merino Cranmore Bloodline 20.56 70.27 6.79 8.39 40.04

2 6 Merino Merinotech Bloodline 21.31 71.32 6.31 7.23 32.53

3 3 Merino Esperdel Bloodline 22.8 76.66 6.86 6.15 32.33

4 2 SAMM X Merino 24.5 68.44 5.11 5.62 19.65

5 1 Poll Dorset X Merino 27.72 75.12 5.31 4.7 18.75

6 5 Border Leicester X Merino 29.2 76.67 5.02 4.42 17.03

Table 1: Results of the first shearing of the Esperance ewe productivity trial

2 5

3 0

3 5

4 0

4 5

5 0

5 5

6 0

6 5

7 0

9/06

/01

20/0

7/00

17/0

8/00

14/0

9/00

17/1

1/00

10/1

2/00

10/0

1/01

7/02

/01

Liv

ewei

ght

(kg)

1 P D o rsX M er

2 S A M M X M e r

3 M er in o

4 M er in o

5 B o rd erX M er

6 L in k -M erin o

-250

-150

-50

50

150

250

350

Jun-

Jul

Jul-

Aug

Aug-

Sep

Sep-

Nov

Nov-

Dec

Dec-

Jan

Jan-

Feb

Liv

ewei

ght

Chan

ge

(g/d

ay) 1 PDorsXMer

2 SAMMXMer3 Merino4 Merino5 BorderXMer6 Link-Merino

1 .50

2 .00

2 .50

3 .00

3 .50

20/0

7/00

17/0

8/00

17/1

1/00

10/1

2/00

10/0

1/01

7/02

/01

Condit

ion S

core

1 PD orsX M er

2 SA M M X M er

3 M erino

4 M erino

5 B orderX M er

6 L ink-M erino

prior to lambing. After lambing finished, lambing percentages were recorded and the lambs tagged.

Weaning At weaning all lambs will be weighed and their progresss followed through to slaughter so that the perfomance of the ewes in each team as prime lamb mothers can be compared.

Second ShearingThe ewes will be shorn for the second time in April or May 2002, and the objective measurements will again be combined with fleece weight to get an average value for each team.

Joining – March 2001 White Suffolks were used as the terminal sires and were introduced at the beginning of March for a six week period.

First Shearing – 11th of June 2001 Mid-side samples were collected prior to shearing and tested for micron and yield. On the day of shearing, greasy fleece weights and a spot auction price were combined to give a value for each fleece. The Merino teams (ranked 1 – 3) performed better than the first cross teams for wool characteristics (Table 1).

Lambing – August to September 2001 Teams were put into separate paddocks two weeks

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Ovine Observer,

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Narrogin WA 6312

Fax. 08 9881 1950

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Contact List

Esperance Fiona Jones (08) 9083 1111

Albany Brown Besier (08) 9892 8444

Katanning Michelle Mayers (08) 9821 3333

Jerramungup Sandra Brown (08) 9835 1177

Narrogin James Skerritt

Erica Schelfhorst

Eliza Dowling

(08) 9881 0222

(08) 9887 5095

Merredin Roy Butler (08) 9081 3111

Darkan Ashe Briscoe (08) 9736 2002

South Perth Bronwyn Clarke (08) 9368 3470

Three Springs Liz Rogers (08) 9954 1004

Geraldton Matthew Young (08) 9921 0506

University of WA

John Milton

Rob Davidson

(08) 9380 2540

(08) 9380 1953