Livestock eNews NOVEMBER 2000

Livestock eNews is derived from SAC Sheep Beef Notes. Please credit SAC with copyright if articles are reproduced in newsletters substantially unchanged. The views expressed are not necessarily those of Intervet UK ltd.

LIVER FLUKE CONTROL

The last couple of years have seen an unprecedented increase in liver fluke disease (fascioliasis) in the UK. Recently published statistics from the veterinary investigation centres indicate that recorded outbreaks of chronic fluke disease in 1999 were over twice the total for 1998, and almost four times greater than 1997.

Until recently fascioliasis was a very uncommon diagnosis amongst sheep in the eastern parts of Scotland. Now cases of the disease are diagnosed by all eight of the SAC Veterinary Science Division labs and the centres at Aberdeen, Perth and St Boswells have all reported the condition in flocks which have had no previous history of fluke problems. Meat inspectors working in Scottish abattoirs have also reported a marked increase in carcasses showing evidence of liver fluke infestation.

An outbreak of fascioliasis recorded by the St Boswells centre in January of this year is typical of those seen in other parts of Scotland. A total of 20 ewes from a flock of 500 showed ill thrift and died over a period of three weeks. The shepherd reported that a further 15 ewes were progressively losing weight. Post mortem examination of two animals revealed condition scores of 1.5 and carcasses which were anaemic and jaundiced. Both ewes were found to have a severe liver fluke infestation, with adult fluke in the bile ducts and extensive liver damage due to the migration of the immature stages.

The explanation for this increase in fascioliasis outbreaks seems to be the recent series of wet summers. High rainfall combined with the warmer summer temperatures, have created ideal conditions for the common mud snail which plays a vital part in the liver fluke’s lifecycle. As a consequence the numbers of immature flukes present on pasture and available to infect cattle and sheep has become very high indeed.

A high level of liver fluke infection is certain to have been carried over from last year and the conditions this summer have again favoured the snail population. As a consequence the risk of infection this backend is again likely to be very high. It is advisable that even stock on traditionally lower risk farms should be treated this autumn, preferably with a dose which kills all three stages of the parasite. On problem farms, Clostridial vaccines which prevent Black disease should also be used, as fluke damage can predispose sheep to this condition. Consideration should also be given to the dosing of cattle over the winter since they can be a source of fluke infection to sheep on the same farm.

If you haven’t experienced fluke infection before but are concerned about the possibility this year, discuss it with your own vets.

GB

USING THE RIGHT WORMER FOR THE JOB

The latest New Zealand and Australian studies indicate farmers are better advised to use the right wormer for the job needed than concern themselves about drench rotations which are not effective at reducing the development of anthelmintic resistance.

Full gut dosing

White drenches, eg benzimidazoles, are much more effective at killing worms if they are given on an empty rumen. This is because the anthelmintic is absorbed from the rumen into the blood where it then binds to the parasites. A rumen full of feed absorbs the drug and it is passed quickly out of the rumen with the feed. The longer the concentration of anthelmintic is at the critical level for the worm species targeted the better the kill. This kill zone can be extended by several hours if the sheep are drenched after withdrawal of feed, preferably for 24 hours, but certainly overnight.

For heavily pregnant ewes or young lambs, this can be too stressful so in this situation it may be better to use a clear drench, eg levamisole, which acts directly on the worms (think of it like napalm going through and burning off the worms!).

Thinking of dosing your ewes pre-tupping? You wouldn’t spray for thistles without checking the field first so why drench when it may not be needed? Mature ewes rarely need drenching. Increases in lambing percentage may only occur where the faecal egg count is over 300 epg. However, thin ewes and gimmers trying to grow may have their immunity depressed owing to their higher requirements for protein and may have higher egg counts and can justify separate grouping. Avoid running these classes of sheep on next year’s grass for grazing twins. A pre-tup drench can safely be done with a white drench on an empty rumen.

JEV

WELFARE CODES FOR FARM LIVESTOCK

NEW SHEEP CODES PUBLISHED

All farmers need to note they have a statutory obligation to see that people working with stock have access to the welfare codes and have been given guidance on their use. This note brings to your attention some of the most important changes in the welfare codes for sheep since the last edition published in 1989.

The new code has emphasised the philosophy of the five freedoms.

Put simply, management must avoid:

hunger and thirst
discomfort, pain and distress
injury
disease
allow the animals to express natural behaviour.

Make sure it is clear who is responsible for the sheep, eg for away wintered sheep – write responsibility into the contract.

Stockmen need training and sufficient time to see to welfare problems – no specific flock size is laid down nor could it be – a flock of 200 can be too much if there are no facilities whereas a flock of 2000 may be feasible with the right set-up and good contractors available.

A new requirement is the need for a written health and welfare plan covering the yearly cycle of production. The SAC sheep health calendar is an excellent basis for such a plan which can be drawn up with veterinary and technical help and reviewed annually. The code recommends management practices (eg clean grazing) to avoid over-reliance on drugs and the use of a quarantine area for newly purchased stock for four weeks with a separate lambing area for bought-in sheep to avoid spreading abortion. Foot care should be part of the plan with on-farm slaughter of chronic cases as they cannot be transported if they carry a foot.

Current medicine records and combined movement book are considered adequate. Additional recording of flock condition score is advised with the information being used to protect welfare, e.g. attention to lowland ewes below condition score 2 and hill ewes below 1 ½.

Attention is drawn to:

	safe disposal of vaccination needles;
	keeping fields clear of wire or plastic dangerous to sheep;
	the need for a run back area/straw bedded area for sheep on roots;
	not catching sheep by fleece alone nor dragging by horns, ears, fleece or tail’
	no tethering by horns;
	the need for sheep to be shorn once/year. Contractors to disinfect their equipment between flocks;
	castration only where necessary (not necessary where lambs slaughtered before reaching sexual maturity; ie about 6 – 7 months) and only after the ewe and lambs are properly mothered up;
	rubber ring legal only in first week of life, no castration without anaesthetic over 3 months of age (no change here);
	segregation of sheep with footrot from the rest at housing;
	where possible maximum pen size for housed sheep is 50;
	sheepdogs should be regularly wormed.

The new welfare codes are considerably longer but no-one could deny that they are fair. With increasing consumer awareness of production methods in livestock systems, they should be looked on as allowing us to protect our market share, maintaining the image of lamb production as natural and welfare-friendly.

JEV

LIVER FLUKE IN SUCKLER HERDS

Liver fluke is an extremely severe disease in sheep, responsible for high death rates in the acute form and severe loss of body condition in the chronic form. Acute liver fluke is most commonly seen in the autumn while the chronic disease affects ewes through the winter and into the spring. In cattle liver fluke causes less severe disease as the acute form of the disease does not occur. However, the chronic form of the disease may be an important contributor to the loss of body condition over the course of the winter in suckler cows. The increased summer rainfall we have seen in the past few years has encouraged the semi-aquatic snails that are involved in the life cycle of the fluke to flourish. In turn fluke problems have been more severe and have been seen on farms where the disease was not thought to occur. Liver fluke control may now be something you should consider in your herd.

Recognising Fluke in Cattle

	Loss of body condition in winter. Adult cattle may scour and when most severely affected they may have 'bottle jaw'.
	Laboratory Tests: These are perhaps less precise than in sheep, but anaemia and biochemical evidence of liver disease are used. Dung samples can be examined for fluke eggs.
	Disease in sheep: If the disease is present in the sheep on the farm then assume it will be present in the cattle.

Control of Fluke in Cattle

Where fluke is known to be a problem or has been recently confirmed in the cattle or the sheep the adult cattle should be dosed with a suitable fluke treatment. Treatment programmes vary according to the degree of exposure and in high risk areas repeat treatments from September to January at 2 month intervals may be required.

For cattle that are housed all grazing animals that are exposed to fluke parasites should be dosed with an appropriate fluke treatment two weeks after housing.

For outwintered cows the minimum requirement in fluke areas is a single dose in December. For the best advice on choice of fluke treatment and the timing and frequency of treatments you should consult your vet.

GC

THE ROLE OF SEXED SEMEN IN THE SUCKLER HERD

Sexed semen is here today – admittedly only in terms of sexed Holstein semen to produce heifer calves. However, it is certain that within one to two years sexed beef semen will also be commercially available. What effect is this likely to have on the future suckler herd?

Sexed semen in the dairy herd

Previously over 60% of all dairy cows have been mated to dairy bulls to produce sufficient heifer replacements with less than 40% being mated to beef bulls. Undoubtedly dairy producers will reasonably rapidly take up sexed dairy semen to eliminate the purebred dairy bull calf which many dairy producers have been slaughtering at birth since the removal of Calf Slaughter Scheme. The immediate effect of this will be to reverse the recent dairy v beef semen ratio with perhaps approaching 60% of dairy cows producing beef cross calves in the future.

With the almost routine use of AI in the majority of dairy herds, dairy farmers will rapidly take up sexed beef semen to produce entirely bull calves. This change would be extremely cost effective to the dairy producer with the current differential between beef cross heifer and bull calves being well over £100/hd – even remembering that even with normal semen half the calves will be male.

In broad terms the effect of this would be to increase by around 50% the number of beef cross calves coming from the dairy herd. However, the effect on the proportion of bull calves coming from the dairy herd would not be particularly great. Even assuming all dairy farmers use sexed semen the number of bull calves would only increase by around 20% ie from around half of the current annual calf crop to around 60% of the future calf crop from the national dairy herd. (It is important to remember that currently there is still a significant number of purebred dairy bull calves being slaughtered at birth so that the potential effect of sexed semen would be to possibly double the number of male calves potentially claiming BSPS coming from the dairy herd. To a small extent this would be offset by the continuing reduction in the size of the national dairy herd which is currently running at around 3% fewer cows each year.)

How will sexed semen be used in the suckler herd?

The impact of sexed semen will be much slower in the suckler herd with currently only around 5% of the national herd being actively A.I.’d. In fact many herds eg large extensively grazed spring calving herds will probably never be able to economically use AI regardless of the potential benefits sexed semen might provide.

Possibly the initial use of sexed semen will be to use heifer semen in those herds breeding their own heifer replacements. This would eliminate the "by-product" male calf and allow a higher proportion of the herd to be mated to more productive terminal sires. An added benefit in this situation would be that where the herd is synchronised to allow AI to be used then all future heifer replacements could be born to the first AI, ensuring they all are almost exactly two years old when they themselves calve two years later.

What proportion of the UK suckler herd will use sexed semen to produce male calves is more problematic. To a large extent it will depend upon:

The ease and cost of using AI eg the cost of the synchronisation programme

The additional cost of sexed semen compared with non sexed semen. For example in our current synchronisation programme at Bush we are using two inseminations, 24 hours apart for each of our fixed time inseminations. Hence on average we are using around three straws per pregnancy so that if the premium for sexed semen is £10/straw we would be investing around £60 for each additional bull calf – almost equivalent to the current steer BSPS claim!

Whether the same conception rates can be achieved with sexed semen compared to unsexed semen.

The genetic potential of the bulls whose semen is used for sexing.

The commercial marketing for sexed semen will have an impact on the suckler herd over the next few years, through its more rapid uptake in the dairy herd and the effect that will have on calf numbers, types and potential BSPS claims. In comparison the uptake of sexed semen by the suckler herd itself will be much slower and largely dependent on the development of cheap and effective ways of using AI in large commercial herds.

BL

DECLINE IN DAIRY HERDS

INCREASED RISK OF FARMERS LUNG

Many producers will be faced with damp mouldy straw for both feeding and bedding stock this winter. This will obviously increase the risk of Farmers Lung – which is still a major occupational disease hazard for those working with livestock. The solution is to always wear a suitable dust mask when handling mouldy feeds. Dust masks must also be worn when shredders etc are being used to bed cattle – the shredding of the straw increasing the number of infective spores in the air. Suitable masks should be of EN 149 FFPI standard and disposed of/replaced as per the manufacturers instructions.

BL

REDUCING REQUIREMENTS FOR STRAW BEDDING

Unfortunately there is no easy solution to reducing the amount of straw required to bed stock – the only approach being to pay "attention to detail".

Try not to use wet straw

The objective of bedding stock is to keep animals clean and dry. Using very wet straw eg straw which has been lying outside after a very wet period, will simply make the bed wetter and less firm so that the cattle sink into it more. The end result could well be even dirtier cattle than if they had not been bedded!

Although to my knowledge the trials have never been done, it might well be sensible where wet straw which has been stored outside has to be used for bedding, to take off the outside 5 – 6" and throw it straight into the midden and only use the dry centre to bed the cattle.

Avoid excess water getting into the building

Excess water from leaking water troughs, gutters etc greatly increases the amount of bedding required. Although we give this advice every time there is a shortage of straw I am sure nobody ever pays any attention to it! However, if repairing a leaking gutter/water trough saves one bale of straw per month (and the labour of rolling it out) it would be a very cost effective couple of hours checking buildings now.

Using a scraped feeding stance

Around 40% of the dung and urine is produced by cattle while they are eating. Putting in a concrete feeding stance which can be scraped once or twice a week has been shown to reduce bedding requirements by almost a third. Where the layout of the building does not allow a feeding stance, is it possible to allow the cattle outside to be fed on a concrete pad which again can be scraped once or twice a week?

In some areas another approach might be to use large woodchips to make an outside feeding area for the cows, providing the base is well drained. However, it is likely that after one winter the woodchips would need to be completely replaced due to the very high level of dung and urine being deposited per square foot.

Type of diet

The ration cattle are fed can have a big effect on the amount of straw required to bed them – silage based diets having the highest bedding requirement. Hence, the amount of straw required just to bed dry spring calving cows on a silage diet will be nearly sufficient to both feed and bed cows on a straw based diet.

Unfortunately however for many of us Murphy’s Law has worked this summer, we have made large amount of silage to feed this winter but have little straw to bed them!

Alternative bedding materials

Most of the alternative bedding materials eg shredded paper, sawdust, sand etc are not particularly successful due to their lack of structure, ie animals sink through the bedding rather than walking on top of it as they do with conventional straw bedding. If such materials are going to work it will be on diets which produce small amounts of dry dung, ie intensive barley beef type finishing systems rather than with silage based diets.

Several years ago SAC ran a small investigation into the use of large woodchips to replace straw bedding in a conventional roofed cattle court. The woodchips were extremely effective for just over two months of the winter, after which they began to get increasingly dirty. (We think the problem may have been due to the court having a concrete floor so that the urine etc draining through the woodchips could not get away and gradually built up.)

Rather than clean out the woodchips we started to use conventional straw bedding on top of woodchips. Over the following three months we used around 1/3 less straw to bed the cattle compared with normal straw bedded yards – apparently due to the straw remaining drier, with any moisture etc draining through into the woodchips.

While it is questionable whether using large woodchips (similar to those used in outside corrals) in a housed situation is cost effective, the trial did show the importance of having drainage in the base of the bed to help keep straw dry and reduce bedding requirements. Hence, where there is a choice of sheds with earth/rubble floors and concrete floors it could well be sensible to house cattle who are likely to produce the wettest dung and need the most bedding (eg animals on silage diets) in the sheds with the earth/rubble floor.

Factors influencing the amount of straw bedding required

Straw requirement	Effect of building	Effect of diet
Zero	Slatts/cubicles/corrals	-
Minimum \| Maximum	Earth floor	Barley beef
	Scraped feed stance	Hay rations
	Concrete floor	Silage/roots

An earlier turnout

The period to save most straw bedding is by turning cattle out earlier in the spring rather than keeping them out longer in the autumn. One reason for this is the long term effects of poaching – areas poached in the autumn tend to result in bare weed patches the following summer whereas areas poached in the spring, when grass is growing vigorously, tend to rapidly recover, filling in the productive grasses and clover.

BL

SHOULD TIMING OF FINISHED CATTLE BE DELAYED TO CLAIM THE INCREASED SLAUGHTER PREMIUM NEXT YEAR?

The answer to this is simple – NO!

The value of the Slaughter Premium, payable on all slaughtered animals, does double next year (2001) from the current level of just under £17/head to just over £33/head but –

	cattle slaughtered this year will receive around 60% of the £17 Slaughter Premium by the end of this year with the balance being paid in April 2001. In comparison cattle slaughtered next year will not receive the initial Slaughter Premium payment until after October 2001, with the balance not being paid until spring 2002.
	for units working with an overdraft having the money in the bank 12 months earlier will save around £1.50 interest charges.
	finished cattle prices peak for the Christmas market and then drop by around 5p/kg carcass weight for cattle slaughtered in January/February. On a 300kg carcass this is a drop in sale value of £15/head.
	as cattle approach slaughter their liveweight gain drops but their feed intake remains high – ie feed conversion efficiency falls rapidly. Daily feed costs are therefore greater than the value of the daily liveweight gain.
	on units claiming Extensification Premiums, delaying sale of cattle could well result in the Extensification Stocking Rate being exceeded.
	feeding cattle over Christmas and New Year increases overtime payments.

The decrease in sale value and interest lost by delaying sale of finished cattle until early next year is identical to the increase in Slaughter Premium so that when all the additional costs of keeping cattle are taken into account the result will be a net loss. The best option, would be to ensure cattle are well feed (and improve feed conversion efficiency) in the autumn to ensure they can be sold when prices are at their highest for the Christmas market in early December.

BL

WHOLE GRAINS IN CATTLE DUNG - SHOULD YOU BE WORRIED?

Many farmers will have treated moist barley or wheat with urea for the first time this year and will shortly be opening up the pits and feeding it whole to cattle, either ad lib in an intensive system or as a supplement to silage or straw. It is inevitable that some whole grain will pass through the cattle undigested on this system and this may give cause for some concern. However, to put this in perspective, it should be remembered that a 450 kg beast fed ad lib on urea wheat will eat the equivalent of about 9 kg of dry wheat and this amounts to 180,000 wheat grains daily. The corresponding figure for 9 kg of barley is an intake of 225,000 grains per day!

Given these figures, a few whole grains visible in the dung is of no significance whatsoever. Even if the dung appears to have a lot of whole grains in it, it looks far worse than it actually is because, with highly digestible diets such as these, any whole grains passing through are concentrated in the very small amount of dung produced. A simple calculation can be done to illustrate this. Wheat is 90% digestible so feeding 8 kg of wheat dry matter only produces 0.8 kg of undigested dry material in the dung. If only 2% of the whole wheat grain eaten passed through the animals undigested this will amount to about 0.2 kg DM of intact wheat grains in the dung. This means that about 20% of the dung dry matter will be whole wheat grains and at this level will be clearly visible but it only represents a very small amount of the wheat eaten.

Even with moist rolled barley there will always be a small amount of whole barley visible in the dung if the barley has been processed properly. Barley should not be over-processed, ie rolled too thinly or ground too finely, because this results in lower intakes and poorer feed conversion ratios and can lead to digestive problems - acidosis and bloat etc. Barley should be rolled to about half to two-thirds of its original thickness and this will result in some of the thinner grains not being processed and these are the ones that pass through undigested.

Although at first sight the appearance of whole grains in the dung may appear to be wasteful, in most situations this is nothing to worry about as it looks a lot worse than it actually is.