With more calves hitting that ground and cold wet weather systems passing through, the Central-West is in the midst of a “perfect storm” for grass tetany!

Grass tetany is a highly fatal disease associated with low magnesium in the blood. Symptoms include muscle spasms, aggressive behaviour when disttrubed and convulsions. Affected cows are commonly found dead in the paddock.

It is possible for grass tetany to affect all classes of cattle but in our region this is a disease mostly seen in a specific population of cattle after significant weather conditions

So who are they?

The high risk cattle are aged (>5 year old) cattle on lush, grass dominant low fibre pastures during last 2 weeks of gestation and during the the first 6-8 weeks of lactation.

This is because magnesium is poorly stored and a large component of milk. Therefore a double edged sword for old cattle; old cows will produce more milk and are more likely to ‘milk off their back’ and as they age they become less efficient at mobilising that small amounts of magnesium and calcium that they have stored.

Why now?

Magnesium is poorly stored by the cow and because of their lactational needs for magnesium they require constant amounts in their rumen.

At this time of year lactating cows are eating lush high protein, low fibre grass dominant pastures. Such diets create a very fast passage time of nutrients in the cows rumen therefore limiting time for absorption of the magnesium through the rumen wall

And then there is the weather! We are all exposed to some nasty weather changes; snow, rain and 3-5 days of average day temperatures less than 10 degrees. For the cows these weather changes do too many things; firstly because they are in heavy condition they are happy to stopy grazing and “milk off their back” therefore they are not getting their daily magnesium requirements. Secondly, these weather conditions have impacts on the normal nutrient cycling of pasture. When stressed due to prolonged cold conditions reduce the availability of calcium and magnesium keeping within and increase potassium (a potent blocker of magnesium absorption). In fact, this sort of weather stresses all sorts of plants, and for plants that can be toxic, the levels of potential toxins will be increased compared to normal.

Grass tetany is a complex disease! There are some important points that local farmers should understand so that they can better aim to prevent it from happening or act quickly to limit losses and possibly improve treatment.

Its an issue of supply and demand. In the herds, the issue is insufficient Magnesium intake. Cows have poor storage and mobilisation of Magnesium therefore immediate intake is critical.

The complicated version of why this is so complicated: Low magnesium impacts the normal functions of nerves and muscles. Hypomagenesiama also affects Calcium metabolism by reducing hormone secretion in response to hypocalcaemia and by reducing tissue sensitivity to parathyroid hormone. Magenesium absorption from the rumen is dependent on Magnesium concentration of Magnesium in the rumen fluid and the integrity of the Magnesium transport mechanism, which is a sodium linked active transport process. High potassium reduces Magnesium absorption from the rumen.

Cows have poor storage and mobilisation of magnesium therefore consistent and immediate intake is critical. Inadequate intake of food is a problem- whether cows are feeling unwell and not grazing, or food is unavailable (eg. cows are yarded). Magnesium may also not be absorbed if there is excessive potassium in the diet, or if there is excessive dietary protein. 

Grass tetany is seasonally and regionally hugely variable. 

Preventatives
*Application to promote plant uptake is unreliable as Magnesium metabolism and uptake in the plant is very complex.
Pasture application is a short term fix with high risk situations - this can get you out of a mess when the stakes are high and problems have been seen.

*Lick Block/Dolomite and salt
This is okay for low risk situations but there is variable uptake by individual animals. You must ensure there are adequate numbers of blocks or trough space for all animals.

Prevention in moderate to high risk
Hay feeding (even though there's plenty of pasture)

Prevention in High risk
Hay and Magnesium or molasses and magnesium, or bullets and loose licks
This needs to be fed every second day at a minimum with additional feeds in dirty weather.
An allternative: molasses and CausMag 50:50 in 44 gallon drum halved
Or Magnesium Capsules 2 weeks pre-calving

Please discuss with us so we can help with the steps necessary to mitigate the risk.

Calves and lambs are very similar to rear. They share a common feature in that their survival is largely related to the amount of colostrum they consume in the first 24-hours of life, and that they need warmth, shelter and somewhere clean and dry to lie down.

Colostrum

If the calf you have is under 24-hours of age, it’s worth trying to source colostrum for them. This is easiest done by finding a freshly calved heifer or cow and milking colostrum from them. If you are struggling to get colostrum, an injection of oxytocin into the cow will help with let down from her. If you can’t get any colostrum, there are commercial supplements available. Ideally, 2-3L for beef calves will suffice.

Feeding

Aim for calves to drink 10% of their body weight (~4L) each day in their first week of life, and 20% of their body weight daily (~8L) after that. This can often be achieved by feeding every 12 hours. The easiest way to feed orphaned calves is on commercial calf milk replacers. The higher priced ones contain higher levels of fat and protein, and are preferable.

Aim to also introduce a hard feed (calf pellet / muesli) in the first week of their life. The aim is to get calves eating 1.5 to 2kg of this per day, at which point, they can be weaned. This is often around eight weeks of age and 70 to 80kg. At this point, they should have doubled their birth weight.

Other considerations

If they are male, they should be castrated as early in life as practical with the use of pain relief.

Vaccinations should also be done at six weeks of age and then boosted four to six weeks later.

Managing weight gain and metabolic upsets during peak pasture growth

Spring is a great time for lush pastures and horses enjoying moist nutritious grass to which we all think horses should have unfettered access. However, like an unlimited voucher to Maccas, too much of a good thing can lead to uncomfortable consequences. In many parts of Australia, pasture grows at its fastest about mid-September and these spring grasses contain highly soluble sugars and fructan - the equine equivalent of junk food.

Manage feed intake

Managing the amount of grass a horse eats is something that takes time and planning. Depending on the area and types of paddocks a horse is grazing in, strategies like restricting the area available for grazing, restricting the duration and time of day that a horse has access to pasture or even using a grazing muzzle can help you restrict their feed intake at this time of the year. Grazing muzzles should be well fitted and managed to ensure good socialisation and normal behaviours. 

Obesity risks

About 25% of pleasure horses in Australia are obese. The health risks due to obesity include:

• Impaired performance
  
  
• Increased joint injuries
  
  
• Metabolic syndrome
  
  
• Heart disease and circulatory problems
  
  
• Respiratory ailments
  
  
• Laminitis (see below)

This is a common problem with a series of serious consequences, so getting good, professional advice to suit your circumstances can save a lot of stress, heartache and money in the long run.

With a large amount of energy potentially coming in, managing how much the energy is used is also important. Therefore, increased exercise is an essential element to include in your plan, as long as it’s safe to do so on veterinary advice.

Monitoring your horse’s weight is also an important activity at this time of year. There are several sites that can help you to estimate your horse’s body condition score. This is the most effective tool to ensure you avoid any problems due to the abundant feed on offer in many parts of Australia at this time of the year.

Every year, during the spring and autumn, we are asked: how do I look after an orphan lamb?

Could you foster it?

Fostering is the easiest option if a suitable ewe is available. Confine the ewe and lamb in a restricted area with food and water until the relationship is firmly established. Often you’ll need to hold the ewe several times a day, or confine her in a way that prevents her rejecting the lamb. Make sure the lamb is getting fed and is not getting quiet or weak. 

Colostrum first

Colostrum dramatically reduces the chances of lambs becoming sick. Ideally, this is harvested from a ewe which has just lambed. Aim to get 100 to 150ml of colostrum. Cow’s colostrum is also suitable for lambs, and commercial supplements are available.

Hand rearing

Once greater than 24 hours old, you can move the lambs over to milk feeding. Lambs require liquid feeds for the first few weeks of life, and won’t start eating good volumes of solids until they are three weeks old. Ewe’s milk is much higher in fat than cow’s milk - this is why it makes great cheese! Commercial replacers, like Wombaroo Sheep, are available and are ideal. In the instance this is not available, you can simply fortify cow’s milk by adding full cream milk powder. The most common problem with feeding is feeding too much too infrequently. Young lambs should be fed four to five times a day, and reduced slowly down to two feeds a day, once they are five weeks old.

Once three weeks old, concentrates should be offered. This will make the weaning process easier.

Other considerations

If the lamb is male, they should be castrated as early in life as practical with the use of pain relief. The same goes for tail docking with pain relief.

Vaccinations should also be done at four to six weeks of age and then boosted four to six weeks later. We can help arrange this at the clinic if you only have a few lambs to vaccinate- just call to arrange an appointment.

For more specific advice on looking after your lambs, give our team a call.

Why are hoofs affected?

Laminitis is caused by a body-wide metabolic disturbance, which is usually recognized by lameness. Many horses suffering from this all-too-common disease adopt a ‘sawhorse’ stance to minimize pressure on their hooves. 

Foot focus

The laminae provide the interface between the coffin bone and the wall of the hoof in a horse’s foot. The blood supply of the lamina feeds the wall of the hooves. In laminitis, this vital blood supply is diverted away from the laminae, starving this vital tissue of the nutrients it needs. During this process, the cells of the lamina can die, disrupting the structure of the foot, which can cause permanent damage in 20-30% of affected horses. In the process, this causes the horse significant pain.

Lush feed

One of the causes of laminitis is unrestricted grazing of lush pasture. So, the risk of this debilitating condition is higher at this time of the year. We saw many, many cases with the great season we had this time last year.

Many pastures are dominated by grasses rich in water-soluble sugars and other sugars called fructans, which are more suitable for high-production cattle and sheep. These fructans can’t be digested in the stomach or small intestine of horses, so they make their way to the large intestine, where they are digested and cause disruption to the gut flora. This disruption causes the death of many bacteria that then produce large amounts of exotoxins. The resulting exotoxin storm disrupts blood flow to the feet, which results in laminitis.

Grazing management

Knowing your pasture and planning feed management as detailed above is vital to minimize the risk of laminitis this spring. If your horse or pony does seem sore, give us a call to arrange a vet appointment. 

A recent episode of the Talking Biotech Podcast was particularly interesting, exploring how researchers are working on methods to manipulate the sex of offspring utilising genetic editing.

Male cattle (bulls) convert feed calories to weight gain more efficiently than females (cows). If more bulls could be put into beef production, the process would be even more sustainable. Dr Alison Van Eenennaam and her research team attempted a clever trick to skew the ratio of males to females in cattle offspring. Sex determination in mammals is driven mostly by a single gene on the Y chromosome, so what if this gene was duplicated elsewhere in the genome? Using CRISPR gene editing, this is exactly what they did. 'Cosmo' the bull should produce 75% male offspring. Dr Van Eenennaam talks about the gene, its mechanism of action, the process of editing a bull’s genome and the regulatory climate around gene-edited beef.

Follow this link to listen.