Lamb Finishing Workshop – Review and Planning

Lamb finishing seems to be an ever evolving game. We explored the subject at the recent lamb finishing workshop in Omarama. It was hosted now as this is when the end result is being measured for fine wool hoggets and it is when the main decisions about winter feed and forages are made. Topics covered were:

• The 2 Q’s: Feed quality and quantity.

• Some calculations on requirements and feed efficiency.

• Fast lamb slow lamb systems. The balance of terminal v maternal hoggets.

• Forage options for the seasons

• Addressing inefficiencies of disease, deficiencies and parasitism.

For me it was an attempt to address the issues of efficiently and sustainably wintering hoggets with less of a reliance on drench chemical to achieve production (without mentioning the topic of drench until the end).

Assistance from local Catalyst agronomist Cameron Lowery and Geoff Mavor was much appreciated.

Summer feeding was not controversial, although there are now brix meters being used to test lamb finishing feed for soluble sugar levels and predict lamb growth rate performance. The discussion on specialist feeds that are 13+MJME per every mouthful of kgDM are quite spectacular.

The Autumn feed for hoggets is an area of debate and change. We went deep on the challenges of grass for hoggets in this period. It is potentially where the most change is needed to navigate “the worm thing”.

Understanding the cost of maintenance feeding is an interesting subject. The standard merino hogget will average 50-70g Lwt gain per day over the 300 days (weaning Jan to slaughter in October), it will eat around 300kgDM, and at an $8 schedule will net 28c/kgDM eaten. A terminal lamb on farm for 100days will eat 150kgDM, and net 30c/kgDM eaten (at a $6 schedule). So neither system is better. The wool value can really enhance the slow lamb option. The balance of feeding them in the winter needs to be set against the requirements of optimising BCS of twinning ewes in mid to late pregnancy. Farms that have cracked the code of feeding twinning ewes better tend to have more lambs to sell at better weights, get more replacements out of fewer ewes, and are able to enhance the faster terminal lamb production option.

Lamb finishing starts for many at weaning when we switch the milk supply off. Getting this process right with well-adjusted lambs is a current focus, but with an eye on the summer -autumn-winter feed plans. It has occurred to me that this is maybe why farming is never done and why it can wear people out or make the players seem gruff, or never content. There are so many things to catch you out if you’re not paying attention. How do we make peace with that?

Ewes and Lambs – Rotational Grazing or Set Stocking?

Farmer preferences, time of year, farm type and experience will dictate which system is chosen. The theory and realities of each system can also be quite different.

Rotational grazing

The simplest form of rotational grazing is to simply shift mobs between small paddocks every 2-3 days, using an ‘eyeometer’ to assess when sheep need shifted, and to assess which paddock has the most grass for next grazing. At the most technical level, rotational grazing uses accurate assessments of grazing covers to calculate how many grazing days are in a paddock and shift accordingly (see example below), usually using feed budget tools as an aid. Positives include better grass utilisation and growth, lower parasite intakes and an easier way of rationing grass during “pinch” periods. Negatives include increased labour/movements, and more precision and calculation required to make it work. Lambs post tailing (6-12 weeks of age) tend to do better because of a regular higher quality grass (fresh pick) being offered.

Even simple “eyeometer” rotational grazing can be a good tool to reduce drench inputs, incorporate different stock classes to paddocks and utilise more grass. The calculation based grazing needs skill and someone committed to the process to be successful. Don’t let spread sheets lead you astray – numbers might look right, but are sheep getting what they need? Are they eating it or wasting it? Are cover estimates accurate? Matching up the requirements with what’s in front of you seems more of an art than a science to sheep farmers.

Set Stocking

Less technical, but can still produce the goods, but is at the mercy of the season more. In a good year lamb growth rates can be higher than in a rotational grazing system, as (provided feeds not limited) sheep will select out the best diet, theoretically grazing 5% area each day. But rank feed can result. Positives include short covers can better quality. Labour and infrastructure requirements are lower. Negatives; parasite intakes are higher on short pastures; grass utilisation is poorer as, when left to pick and choose, stock overgraze tastier areas and leave less palatable areas to grow long. Stock numbers have to be fairly well matched to grass growth which takes experience of your farm to get right. It can also be hard to assess if stock are actually getting enough and good stockmanship is important to get the best out of it. The farm will grow less grass (as grass grows grass) compared with calculated rotations.

Both systems definitely have their place and many farms will end up using a combination of the 2 over the year. Close monitoring of weaning weights and comparing to other years will help direct you to which system plays best to your strengths. In the trickier years, it seems to be farmers that keep ewes and lambs on the move, draft more lambs. They are likely not to run into as many worm issues. The fertility and response of grasses is obviously key to a good rotation. This does not happen over night.

Johne’s Disease – Is it worth worrying about in deer

What is it?

Johne’s disease is an incurable bacterial disease that affects the intestines of ruminants. It causes the intestinal wall to slowly thicken reducing absorption of nutrients. Animals develop watery diarrhoea and loose condition. Affected animals don’t respond to treatment with drench and antibiotics, there is no cure, and they will almost certainly die.

What does it look like in deer?

Typically, we see Johnes in two distinct forms:

• Major outbreaks in young deer.

• Sporadic cases in mature deer

Major outbreaks in weaner and yearling deer

This typically occurs in the first winter and spring in deer as young as 8 months. Up to a quarter of the mob may be affected.

Weaners fail to thrive, develop diarrhoea, and characteristically have a green scour down the hindquarters and hocks. They rapidly loose condition, have a patchy light coat, and may waste away over just a few weeks.

Parasitism and Yersinia can look similar in appearance but will respond to drenching or antibiotic treatment.

Sporadic cases in mixed age deer

This is normally seen as the odd skinny hind with green stained hocks due to a continuous or intermittent scour. I have occasionally seen stags with Johnes in velveting herds.

These hinds will spread infection to the fawns via in utero spread or via the faeces soon after fawning. It is important that hinds with Johnes are culled before fawning kicks off.

Can much be done about Johnes?

The answer is yes – Johne’s carriers can be identified via blood testing and culled.

A Johnes control programme can look as follows:

YEAR 1

• Blood test all breeding females over 1 year of age prior to fawning, normally this is done in July-Oct. It is important to cull pregnant hinds with visible signs of Johnes or high antibody levels on the blood test before fawning.

• Blood test all sire stags and velvet stags greater than 1 year of age around button drop (Aug-Sept)

YEAR 2 AND ONWARDS

• Blood test all pregnant replacement R2 hinds and replacement velvet spikers in July-Oct.

Talk to me if your concerned about Johnes in your deer herd and want to do something about it.

Feeding for Lamb and Calf Survival leading up to Spring

Heifer Feeding pre-calving

No one wants to be pulling calves from their heifers, and feeding levels in later pregnancy are often singled out as one method of reducing the risk of this. It’s not a great strategy for a few reasons:

1. An underfed heifer will protect the calf by using her own body stores to provide it with energy – thus to reduce the calf’s liveweight feeding levels would have to be will below requirements.

2. Feeding well below requirements has negative flow on effects for colostrum and milk production – compromising calf survival and growth.

3. If heifers have not been grown out well before calving, then their pelvis will not be big enough to easily give birth.

4. Poorly fed or conditioned heifers pre-calving are at high risk of being too weak to push the calf out themselves, or look after their calf afterwards.

Focus instead on sire selection for calving ease, and feeding heifers well throughout pregnancy.

Feeding ewes pre & post lambing

The three weeks before and after lambing are arguably the most critical feeding-wise for your ewes. They’re making colostrum, and then milk to feed growing lambs, growing unborn lambs and putting brown fat on them so they survive after birth, and hopefully not losing too much condition along the way.

At the end of pregnancy, the ewe’s energy needs increase exponentially – if she’s got multiples on board she’ll struggle to eat enough to meet her needs, and start taking it off her back. Prioritise your available feed, especially if this is limited. For example:

a) first cycle, multiple, poorer conditioned ewes – top priority ewes that need to be on higher covers

b) mated hoggets if you have any – these are still growing and need to be looked after

c) better conditioned first cycle multiples

d) everything else – rest of multiples, then singles

This is when having cycle data from scanning is really helpful – there’s a big difference between the amount of feed a ewe needs about 3 weeks out from lambing vs her later lambing friend still over 2 months away – about double! But put in the same paddock, they’re both going to eat the same amount.

Should I separate my triplets? Yes, if you have limited feed, in which case it would benefit them to be better fed. However, if you can keep all your multiples on decent covers (at least 1200kgDM) then there’s no need to do so, they can’t physically eat any more than your twin ewes.

Busy Time ahead for Sheep Farmers

It’s a busy couple of months coming up on sheep farms. Getting some information running up to shearing can help make better animal health decisions.

Main areas to address scanning to pre-lamb are:

• Lice control – review annual plan to control or eradicate. New product options are available. Will the option of flexible, any length wool, oral lice control change your mind-set around lice prevention and control?

• Feet – sort problem feet before set stocking. Footvax can make a difference to your workload and amount of footrot by weaning. If starting out there is a window in July to get sensitizer in now, then boost in September. Tilmovet is still the most effective treatment option available.

• Minerals – Will your flock benefit from longer acting B12/Se/Iodine? Vitamin D. Mineral check of dry ewes at scanning is helpful to decide what to invest in. Ask the clinic for a form to go with the ASD to works to collect samples.

• Prescription drug allocation and pain management for shearing cuts is an area that needs a vet consultation. Ask about our resources to reduce shearing cuts and manage them in a positive way.

• BCS is the buffer that drives most production. What animals need prioritising? We can assist with charts and guidelines for more targeted feeding strategies.

• Worm control:

  Š What is the active burden – Do some mob FECs at scanning

  Š What drenches will work - Pick up a Drench Performance Test from the clinic. Need 50 ewes with average FEC >300 epg to get some useful data.

There is a lot of benefit to making a plan with your vet. Your Territory Manager is here to help make life easier for you dropping off product when needed.

Footvax ACVM A001992

Tilmovet 300 Injection ACVM A011195

Shearing

Reasons for winter-spring shearing may include:

• Improved wool growth and quality.

• Increased lamb birthweight.

• Better lamb survivability.

• Increased ewe feed intake.

• Reduced ewe casting.

The classic Boy Scouts motto “Be prepared” may not earn you a badge this winter but will help to set you up for success. Without a reasonable plan in place to manage winter shearing, it can cause more issues than it solves. Many consider this event at every stage of the year with things like the decision to belly-crutch in the autumn, winter crop planning and when sheltered blocks get grazed.

Feed demand of shorn ewes in winter increases by up to 30% in the month after shearing and it takes two weeks for the grease levels to get back in balance and provide water resistance. Increasing lamb birthweights are typically seen if the ewe has the means to grow a bigger lamb. She needs to have a body condition score of 3 or above to put the extra energy into growing the lamb, rather than putting it on her own back.

Shearing in late pregnancy (within 6 weeks of lambing) has less consistent advantages than mid-pregnancy shearing (14-7 weeks pre lambing). The yarding, cold and nutritional stress in late pregnancy increases the risk of metabolic disease at a critical point in pregnancy, plus can drain the energy that would normally go into building fat stores in the late gestation foetus, reducing lamb vigor.

Overall, pre-lamb shearing does have benefits, but it pays to revise preparations regularly.

Animal health check list for shearing:

• FEC ewes 1 month prior to see if winter worm burden significant. Some ewes may benefit from mid winter drench more than a pre-lamb drench.

• Lice control/eradication plan. It is more than just a pour-on. An annual plan will achieve best results. New products available have changed this space.

• Minerals: Did you address Iodine pretup? The best time for iodine in the system is mid pregnancy when the foetus needs it most.

• Shearing time welfare management (will have more about this in the July issue)

  • Get supplies and a plan to manage cuts and wounds with topical or injectable products. Some of these can be used to treat lameness as well.

  • Have some metabolics on hand for any sleepy sickness.

• Feed and shelter planning is the biggie. What can we do to feed ewes 1.5x maintenance for 14 days after shearing? Its likely to involve something out of a silo, stack or plastic wrapping this year.

Life after Capsules ... the results are in!

Last lambing season was the first when farmers no longer had the option of using Bionic CRC drench capsules. Farmers were forced to look at other options, so we have conducted an extensive survey to see how clients who previously used Bionic capsules managed.

The questions asked included the following;

• What did you do instead of using Bionics?

• How do you rate your ewe performance?

• How do you rate your lamb performance?

• Was the dag score any different?

• If Bionics became available, would you use them again?

Discussion

It is important to recognise this survey represents anecdotal comments from farmers, and this is not a scientific document. However several trends emerged.

• It is really encouraging to hear how many farmers now use targeted worm control programmes, with a mix of long acting injection, oral triple drench, or no drench at all, combined with a range of mineral supplement options. And these decisions are based on real information – age, body condition, twins, pasture contamination, laboratory tests, feed available, etc.

• Most farmers who used long acting injections (Cydectin LA, Exodus LA) to replace Bionics saw similar lamb numbers produced and similar lamb live-weights, and similar ewe losses to previous years.

• Many farmers who went from Bionics to a selected oral drench only, were happy with the season’s production, though this was confused by the associated use of minerals such as Smartshot B12.

• Farmers who used Cydectin LA or Exodus LA reported little change in dag score. Most clients who changed to a single oral drench or no drench reported increases in dags, while also noting the season “dried out” and dags were not really a problem.

• Many farmers reported excellent feed availability during the 2023 tupping, and felt this was the main factor holding their production up. (Certainly, it was a kind season, with heavier ewe tupping weights, -and lots of bearings out!)

• Despite acceptable results without Bionics, many farmers still said they would use some if they were available. Several comments reinforced the desire for long term worm control and cobalt and selenium supplementation in a single delivery system, in selected groups of ewes.

Resistance Monitoring

Worm egg counts 50-80 days after long-acting injections (“leakage”). For many years we have monitored faecal egg counts from ewes treated with Bionics, 60-90 days after insertion, to monitor their effectiveness, keep a check on emerging drench resistance, and make recommendations when exit drenching was required. These egg counts have generally stayed variable, but low, over many seasons of Bionic use.

It was unexpected to find this egg “leakage” was lower this year after long acting injections – 75% of all samples tested had zero or less than 50 epg, and only one test had more than 300 epg (further resistance testing followed this case). We had expected long acting moxidectin injections to show higher egg counts, in the knowledge that its length of action against Trichostrongylus worms was much shorter than Bionic capsules.

Veterinary Summary

So far we have proved we are not reliant on Bionic capsules.

Long acting moxidectin injections appear to be fairly equal in their performance in the field.

Most farmers have taken a hugely responsible attitude with their selection of options for targeted worm control programmes.

Long acting moxidectin injections are still performing as a valuable option in select groups of animals-lighter ewes bearing multiples, under feed pressure, etc.

If long acting injections are used, egg counts should be done 60-80 days after treatment, an essential part of product stewardship for future options.

Provision of adequate levels of high quality feed is the number 1 requirement for sound production-last season proved that!

It is likely the favourable season hid some of the increase in dags most of us were expecting to see.

A HUGE THANK YOU TO THE MANY CLIENTS WHO SO WILLINGLY PROVIDED THIS INFORMATION. IT IS BECAUSE OF YOU WE ARE ABLE TO ENHANCE OUR LOCAL KNOWLEDGE, AND MAKE BETTER RECOMMENDATIONS FOR STOCK HEALTH AND PRODUCTION.

Beef Weaner Calf Health

With weaning right around the corner, it’s crucial to have a plan in place to keep calves healthy and growing strong. Here’s what we need to focus on:

• Parasite Control: Once calves are off their mothers’ milk and onto pasture, internal parasites can limit growth. Effective drench use is the key to staying on top of this. Injectable combination drenches such as Dectomax V or Eclipse E are available or alternatively Eclipse pour-on can also be used.

• Minerals: Two key minerals we need to think about are selenium and copper. Selenium is essential for immune system and overall health. This is where Selovin LA comes in handy – it’s a long-acting option that keeps selenium levels adequate for up to 12 months. Copper is crucial for growth. Copacap copper bullets provide long-lasting supplementation or you can use a copper injection. The Coppermax or Copaject injection is especially useful if wintering on brassicas.

• Vaccination: In order to protect the calves from clostridial diseases Covexin 10 in 1 or Multine 5 in 1 can be used at weaning, followed by a booster a month later. These vaccinations are crucial if going onto fodderbeet.

Summary

• Recommendation at Weaning: Combination Drench, Selenium Supplementation, Vaccination (1st Covexin).

• 5 weeks later: Copper supplementation, 2nd Covexin and drench if required.

So, as we’re gearing up for weaning, make sure you’ve got your bases covered with parasite control, minerals, and vaccinations. It’ll set the calves up for success as they make the transition to pasture-based diets.

Ewe BCS going into Breeding

We all know the importance of having ewes at target body condition score at key times of the year – if they are at target at mating, they are more likely to conceive, thus improving scanning percentages, and more likely to be at target at lambing, which increases colostrum production, lamb survival, increases lamb growth rates and weaning weights and has many flow on effects. In a dry year this is even more important, as the feed needed to get ewes to target BCS is a rare and precious resource. This is why looking at the individual ewe BCS is so important, not the flock average.

Ewe BCS target = 3.0 all year round

Key times of the year to monitor this are:

• Weaning

• Pre-mate

• Scanning

• Pre-lamb

Some of these times are more convenient than others – for example if you’re putting your hand on them to push them onto the scanning trailer, or giving pre-mate minerals. You don’t have to monitor ewes at each of these times, maybe just a couple, and you don’t have to condition score them precisely. The key is to identify and raise the bottom percentage of the flock so that you can put extra feed resources into them, not into those already at target.

1. There is a real benefit to lifting your lighter ewes

An increase of one BCS from 2.0 to 3.0 has been shown to increase scanning percentage by 15%, lamb survival 5%, lamb weaning weights 5% - analysis in 2010/11 gave an gross margin per ewe of $13 (over summer).

2. There is a “law of diminishing returns”

You will get massive relative gains in ewe performance as individual ewes go from a BCS of say 1 ½ - 2 and so on. This trend continues, but the curve becomes less steep – once ewe BCS reaches 3 – 3.5, there is minimal increase in production, whether it be increases in conception rate, lamb growth rates, or other effects of improved BCS. This is why there is no advantage to feeding ewes to gain condition over target BCS.

3. Feeding fatter ewes is inefficient

In addition to this feed being essentially wasted, as it will not improve production, it is also used very inefficiently. It takes a lot more energy – 351MJ – to go from 3.5 to 4.0 than it does to go from 2.0 to 2.5 – only 71MJ. So you don’t even have to put that many kg DM into those light ewes to bring them up to target, emphasising the importance of being able to separate them out and allocate precious feed to only those that need it.

Take home messages – putting precious feed into ewes at target will not improve production. Focus on lifting the individual BCS of lighter ewes at the bottom of your flock. Now is one of the key times you can do this to have a big impact on scanning, lambing, and weaning outcomes.

Dealing with Feet

The current run of hot dry weather has been a great opportunity to tip some ewes over to sort out lingering infection before it spreads again in the Autumn.

The works are getting picky about what is acceptable for transport and processing. Vet certificates can allow them to get priority processing if you do have space.

What are some options if you are having to keep and treat lame ewes for breeding:

• A plan is important. What are the trimmers for, how much do you pare? Do you carry on tipping if there is a lot of scald? What are the daily targets to get through?

• A pre-wash bath, a good handling facility, a set of sharp trimmers (pneumatics for the hard ones) can make a big difference. Don’t make them bleed. Running through pre-wash not only increases sensitivity it also softens hoof for easier trimming. Trimming itself is not a treatment. It is a diagnostic aid.

• CULL mis-shapen, multi-feet infections that are too far gone. Some sheep just keep getting re-infected and have lost too much condition to turn around.

• Antibiotics. There are some useful long acting formulation s that achieve good efficacy provided you do the follow-up (below). Vet only tilmovet is still the best.

• Topical something – a 10% zinc troughing or blue spray into lesions after the diagnostic trim and dose of antibiotics.

• A night on the grating post treatment. This allows feet to dry out and allow treatment reach peak concentration on the hoof. Seems to make a big difference.

• Follow up treated cases. Do this ~14 days after treatment is important. This is to remove dried up lesions and expose any pockets of bacteria that maybe hanging on. Applying blue spray or another zinc troughing after the check is ideal. Antibiotics will relieve clinical signs of footrot, but they can also suppress footrot bacteria that can re-surface 2-3months later, and possibly be more tolerant to subsequent treatments, so this clear-up check and trim is essential.

Footvax sensitizer to clean sheep now can give you options for booster shot pre-tup and/or pre-lamb. For irrigated properties troughing and footvax are your best footrot control tools.

Bulls - Keep Your Eyes Peeled for Poor Performance

Bulls are crucial to the success of any beef breeding enterprise. We place tremendous faith in the bulls to work alone or in small teams and continue to deliver a new crop of calves year on year.

If we set the following aspirational goals for our beef cow mating:

95% in calf for a 3 cycle/9 week mating period.

• 65 calves in the 1st cycle/3 weeks.

• 20 calves in the 2nd cycle/3 weeks.

• 10 calves in the 3rd cycle/3 weeks.

A little time and attention to making sure the bull team is fit, free from disease and actively working is critical to achieving these goals.

During mating

• Check bulls twice each week for the first 3 weeks and then weekly for the next 6 weeks. Get up as close as reasonably possible. Watch each bull walk, check for swellings around the sheath and for lameness. Once bulls are 6 years old and beyond their 4th breeding season, they are much more susceptible to subfertility, poor mating ability and breakdowns. These bulls should be subject to more rigorous scrutiny as they often fail to mate effectively and start fight with the younger bulls. Ideally bull teams would have been matched on age and body weight. I’d be deeply suspicious of a dominance issue if a younger bull has poked up a gully and is constantly “off by himself”.

• Have a spare bull or bulls available to immediately replace any that break do due to lameness, back issues, broken penis or obvious illness.

• Rotate bulls in single-sire groups to make sure that any bull infertility is covered. Single sire joining works well, but it has risks.

After mating

Suspicions may be raised during the mating period, but scanning is the first true indicator of weather these goals have been achieved. Alarm bells start ringing when a higher-than-average empty rate occurs, particularly those results above 20% empty. In these situations, the first question I’m often asked is “could it have been the bulls”. My response is to ask the question “did you have confidence in your bull team during mating” and then to suggest a deeper dive into the scanning data and examination of any suspect or broken down bulls.

The Weaning Process – Expressing your Stocks’ Full Potential

Most of us think of, and treat, weaning as a date on the calendar – something that gets ticked off and moved on from. For the lambs however, weaning is the biggest event in their lives and undoubtedly the most stressful. They are separated from their mums’, taken off milk, often have to adjust to a new feed source, exposed to the stress of yarding, dogs and people, and this all happens very abruptly.

Modern stock have a lot of genetic potential – but if they are not fed well then that potential will not be fully realised. After making that investment you must then give them the chance to express it – which means fully feeding them, especially at key times such as premating, late-pregnancy and lactation, and when they are young growing stock.

If post-weaning growth rates are lower than you would like has a weaning check played a part in this?

The two main areas that will impact how the weaning process will affect the young lamb are:

• The amount of stress it places the lamb under:

  • This comes from handling by people and dogs, changes to their environment, and changes to their management and routine such as being removed from their mums

• The change in feeding the lamb undergoes:

  • Remember we are feeding the bugs in the rumen, not the lamb itself

    – the lamb lives off acid produced by the rumen bugs and they also digest the rumen bugs as a source of protein. Weaning means the final transition from a monogastric animal (milk is main energy source) to a full ruminant (forage feeds bugs in rumen).

Over the ditch feeding grain every few days for a week before and then several after weaning is used to help with rumen transition – it suits their systems as sheep are then accustomed to grain in case of drought. The lambs also get used to people coming into the paddock to feed out in the few days before being handled before weaning, reducing that stress. Here in NZ a more realistic option may be making sure lambs and their mums are on the high quality feed the lambs will be weaned onto before this happens – so lambs and their rumens are used to it.

Any changes you can make to your normal weaning process that will reduce stress on the lambs and ease the transition of the rumen bugs to their new diet will help make this change easier. This can translate to a couple of kg either way – lost or gained – which could add up down the road to several kg for a hogget mated. Getting the rumen bugs cranking also optimises the output of rumen protein – which helps growth rates and resilience against parasitism.

A Clinical Case of Goitre

The lamb pictured is from a local farm around Waimate. The ewes are on grass and they have never supplemented iodine. The enlargement underneath the jaw is due to a condition called Goitre. This occurs as a result of insufficient iodine in the pregnant ewe. The fetus relies on its mother’s iodine intake to transport sufficient iodine across the placenta for its own thyroid hormone production.

Goitre can affect a newborn lamb’s ability to regulate its metabolism meaning they can be highly susceptible to malnutrition and cold exposure. This can reduce lamb survival rates, impair growth, and sometimes even result in stillbirth.

Here are some key strategies for preventing goitre in lambs:

• Balanced Nutrition: Ensure that pregnant ewes are provided with a well-balanced diet that contains sufficient iodine. Iodised salt or mineral supplements can be added to their feed to meet their iodine requirements.

• Monitoring Iodine Levels: Weighing the thyroid glands of 10-15 lambs who are stillborn is the best way.

• Environmental Control: Certain crops like Brassica species can contain elevated levels of goitrogens that impair the thyroid gland’s iodine uptake. Some clover varieties can also have this effect.

• Iodine Supplementation:

Supplementation should be considered if:

• You are feeding brassica crops

• Your farm has a previous history of goitre

• Thyroid: bodyweight ratios from slink/stillborn lambs are higher than recommended

• You have noticed higher losses than expected around lambing

This can be done via an injection of Flexidine - ideally given a month before mating. Alternatively you can use Lamb Survival Drench (LSD). Ideally give 3 doses: Prior to mating (to improve fertility), at scanning and prior to lambing. If not given prior to mating then giving doses at scanning and prior to lambing will provide supplementation for the growing foetus.

Bloat in Cattle

Lush pastures with high amounts of clover or lucerne makes spring a high risk time for bloat especially in young cattle. Bloat is caused by rapid gas accumulation in the rumen. This gas cannot be belched out as it becomes trapped in the rumen contents and forms stable foam.

When cattle are put onto a risky feed they can bloat within 15 minutes and die within 2 hours. If there are early signs of bloat, remove the herd from the offending pasture and feed hay or mature grass/silage. Bloated cattle can be given bloat oil and cattle with severe bloat may need to be stabbed in the left flank to release the gas. Because of the rapid onset, the first sign of bloat may be dead cattle. This can look similar to other common causes of sudden death including clostridial diseases in unvaccinated cattle.

Nothing is 100% effective at preventing bloat but the most reliable bloat prevention can be provided with Rumensin 100 day anti-bloat capsules given a week before being placed on riskyfeed. Other management options include providing fibre, giving bloat oil via troughs and avoiding hungry cattle gorging on highrisk pastures. Rumensin has the added advantage of improving feed conversion efficiency (7-15%) meaning bloat prevention can also improve production/profitability of finishing cattle.

Feeding Mouldy Supplements

Mould is the dust like coloured fuzzy structure that a lot of fungi form when growing conditions are correct. Some fungi form mushrooms and others are single cells that we can’t see with the naked eye but can see changes in the feeds they’re growing on.

There are thousands of species of mould-forming fungi and these moulds can produce hundreds of different toxins (mycotoxins) that can affect the body in many different ways. Moulds may affect the body directly causing pneumonia, mastitis or abortions, or via toxins causing a myriad of symptoms.

Storing winter feed in good condition can be difficult especially during a wet summer like we had this year, and we have had a lot of reports of mouldy feeds.

Mould decreases the ME and palatability of feed, as well as limits vitamins and thiamine. The end result is a feed that tastes bad, won’t make them gain weight and has limited vitamin support.

There is a certain amount of each type of mould cows and sheep can tolerate, the exact amount is unknown so therefore we don’t have a ‘safe’ amount of spoiled feed that you can feed.

The rumen is an excellent ‘decontaminator’ of mycotoxins and moulds, therefore sheep and cattle are more resistant to disease than monogastrics like us, pigs or horses, however dairy cows, high producing sheep and beef cattle around calving may be more susceptible to mycotoxins due to altered rumen transition times and a suppressed immune system. Young calves and sheep with undeveloped rumens are also susceptible.

Clinical signs vary from poor doers and weight loss to pneumonias and abortions. I once saw cows with blistered swollen vulvas from mouldy feed and no other signs, likely due to estrogenic effects of certain mycotoxins, vaginal and rectal prolapses can happen too. Occasionally we see sporadic abortions in sheep and cattle from mycotic placentitis-fungal infection of the placenta (photo below).

Feed analysis is hard because mould growth is inconsistent, the affected feed may be gone before signs are apparent and mycotoxins aren’t uniformly distributed within a feed. Lab analysis is expensive and limited to only a few mycotoxins out of the over 400 known. Diagnosis is usually from the history.

Remember that bacteria like Listeria can also overgrow in spoiled or improperly stored feeds like silage.

The general consensus is white mould is probably okayto some degree, others probably aren’t. If you have to feed mouldy feeds, the main solution is dilution –that is feeding good feed with the mouldy stuff and preferably feeding the worst of it to adult non-pregnant cattle and sheep.

Lice Control

Off shears and pre-lamb, before the next generation of lice residences arrives, is the best opportunity to deal with lice.

Jetting off-shears with short acting knock-down chemical such as Extinosad or Seraphos is cheaper, but jetting is never 100% effective. It just does not totally wet the skin enough. Can’t be that pleasant off -shears in winter conditions.

Off shears pour-on options include Zapp Encore, Magnum, Expo Pour-On and Wipe-out. The IGR in Magnum and Zapp Encore gives persistent activity for 2-3 months. With Zapp Encore there is also a knock down imidacloprid which gives instant kill, this differentiates Zapp Encore from other straight IGR based chemicals. It does have limitations with cover-comb shorn merinos however. Double dose Expo Pour-On may be the best knock-down for lice in fine wool.

The trick is to treat all sheep and do it properly. Don’t leave an island sanctuary around the head and neck for lice to survive.

Winter Footrot Management

With the warm and moist conditions we had over late autumn we’ve seen an increased amount of footrot in flocks. However the drop in temperature over winter means a decreased spread of infection from sheep to sheep, hence an opportunity to control the level of infection in your flock before we head into the spring high challenge period.

Scanning/ shearing are great times to assess and manage the spread of footrot in your flock;

• Tip sheep and examine type and stage of infection also ruling out other causes of lameness such as abscesses, frosted mud burn.

• Remove and treat infected sheep. Treatment options include:

Tenaline (ACVM A007843) or Tilmovet antibiotics (ACVM A011195) - get in touch with your vet to discuss options. For mild early-stage infections Tetravet (blue) spray may do the job. Dave has been experimenting with a “new spread-phase brew” that has shown promise if anyone is interested…

• The “clean” mob can be foot-bathed which will cure grade 1-3 lesions. Ensure sheep are standing in the bath for at least 15 minutes if any under-run type footrot is present.

• Put the “clean” mob onto pasture that hasn’t been grazed by sheep in the past 4 weeks.

• Re-inspection of the “clean” mob is best practice, but difficult to achieve at this stage of the production cycle. So aiming for one last crack at removing footrot from the mob is the best you can do.

Foot work can be a time consuming process but getting on top of the infection in your flock whilst it’s not spreading is a great opportunity to reset the clock on your flocks footrot status. Often management programmes tend to start at the height of an outbreak when the disease is already spreading, but intensive effort when the number of new infections are at their lowest will have the best success.

Vaccination

Footvax will reduce the amount and severity of footrot during the high challenge periods by approximately 50% depending on the season. Protection from the booster lasts for 2-4 months (less for fine wool, more for strong wool breeds), therefore timing’s important so immunity is highest over spring when the challenge is greatest. For first time users, a sensitiser shot will be required at least 6 weeks before the booster shot.

• 1st time users: June/ July sensitiser and 6 weeks later booster dose

• Annual users: timing varies from farm to farm depending on risk period, pre lamb shearing and tailing are common times to give a booster shot

• Don’t vaccinate within one month of lambing.

Mineral Check

Trace elements are the talk of the town at this time of year, when everyone is checking the herd and flock level prior to winter. One very simple option for monitoring those mineral levels is checking the liver stores at the meatworks, with the help of a single piece of paper- the Mineral Check formthat goes with the truck driver. At least 10 animals are required to get a gauge of copper stores in the mob, as it can be variable, but just 5 samples are needed to establish selenium, cobalt and zinc levels.

One limitation of the Mineral Check option is that the cull animals are likely to be the worst-performing of the mob, so may have disproportionately low trace element stores. But it can be followed up by liver biopsies and/or blood tests for trace elements in live animals, to establish the average herd level. Mineral Check is an excellent starting point for establishing the lowest trace element levels and the process is very straightforward. Simply give us a call and we’ll send you a form to fill out. This includes your farm details, the name of the trucking company and the name of the meatworks the animals are going to. Then email a copy to the meatworks, give the paper copy to the stock truck driver with the ASD form, sit back and wait for the results!

A New Way to Drench Lambs

I’ve had a couple of discussions about turning lambs out on to dirty pasture for 2-3 days before shifting onto clean crop or re-seeds etc. Whilst this remains good advice with regards to delaying drench resistance, some farms will be unable to put this into practice for legitimate reasons (big distance between dirty/clean paddocks, no need to shift mob twice etc.) Drenched lambs will leave behind them only worm eggs resistant to the drench used, so when turned onto “clean” pasture, the paddock will build up a population of resistant worms. A technique known as Targeted Selective Treatment (TST) is a means of reducing this risk associated with “drench and move.”

What is Targeted Selective Treatment (TST)?

TST is a drenching strategy. It requires identification of the lambs still achieving good growth even though they’re due to be drenched (ie. identifies the most worm resilient lambs), simply by weighing them and working out a growth rate. Hopefully 10% of the mob can be left undrenched, whilst the rest are drenched as normal. This allows non-resistant worm eggs to be carried on to the new pasture, whilst maintaining production.

How is it implemented?

Usually TST requires an automated calculation of average daily weight gain, with electronic weigh cells and an EID tag. Animals at or above the TST growth rate target are drafted out and left un-drenched. The remaining lambs are drenched as normal before moving to clean paddocks.

How do we calculate the desired weight gain?

The most practical method would be to weigh roughly 70 lambs, calculate the Average Daily Gain (ADG), then sort the rest of the mob according to this figure. Some farms might already know their target lamb growth rates and decide to use these, however the actual growth rate will fluctuate from month to month according to feed, weather etc., so would be best recalculated. You will know quite early on in the day if the figure needs changed – e.g. if the first 20 lambs in the mob are not to be drenched, the weight target is probably too low.

What are the benefits?

The single biggest benefit is that it will prolong the useful life of drenches on your farm. You may also be able to identify your most worm resilient hoggets to keep as replacements. Reduction of drench use/costs will also bring a modest saving.

What are the downsides?

Set up costs for weigh cells/tags, and the additional time required to weigh/sort the mob are considerations – these may however already be in place for ewe lambs in some stud flocks. The technique is unlikely to be appropriate for; Merino’s due to their worm susceptibility and; times of year when larval burdens on pasture are particularly high (Autumn). However, TST is a practical tool to prolong the life of our remaining drench actives, whilst genetics for worm resilience are brought up to the task.

Teaser Rams

It is nearly time for mating to begin for another season. We are tidying up the last of our ram palpating jobs and getting well through the ram teaser surgeries.

Rams should be checked ideally 6-12 weeks before mating. This gives you time to treat any issues you find and they have time to recover.

When checking your rams remember the four T’s: Teeth, Toes, Tackle & Testes, (plus Torso according to the Aussies which means condition score).

For those who haven’t used a teaser ram, they are rams who have been vasectomised so they are sterile but still produce testosterone. They still have normal libido and will mate ewes.

Teasers are used to synchronise ewes and hoggets that are already cycling, and stimulate non-cycling ewes and hoggets to cycle earlier. They may also improve ovulation rate so the number of twins is higher. The ideal teaser ram is healthy, has passed the four T’s test and preferably isn’t a ram lamb.

Teasers are ideally cut 6 weeks minimum before mating so they have time to heal and any viable sperm in the tubes is gone.

Ewes should be isolated from all rams and teasers for 21 days, then the teasers can be introduced 17 days before mating. This should stimulate the ewes to have a silent heat if they aren’t cycling, so they are in their second and more fertile heat when the rams are joined.

Some people recommend using teasers at the normal ram ratio (1:50- 1:100), other suggest 1:300 for hoggets and 1:500 for MA ewes. A New Zealand study concluded that when using teasers for hoggets ratios of up to 1:197 can increase the percentage of hoggets bred in the first cycle by at least 16.4% so 1:200 is what we normally recommend for both hoggets and MA ewes.

Teased hoggets have larger ovarian follicles and heavier hoggets (>36kg) have the best response to teasers as they are more likely to already have started cycling.

Give your local clinic a call if you’d like to book in any last minute ram vasectomies for the upcoming mating season.