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Considerations for optimal animal health

Optimal animal health is achieved by having an evolving animal-health plan, a good relationship with your local vet, and a prevention-is-better-than-cure attitude, vet, Donal Lynch tells Bernie Commins. Here, he outlines some animal-health essentials to focus on

“Now is a great time to plan for the future months, and focus on a number of things such as parasite control, mastitis control, pneumonia control, and fertility,” says Donal, who espouses a holistic approach to general animal health on the farm. “One disease should never be looked at independently of another,” he says.

Parasite control, particularly in relation to first-grazing animals is something to home in on as now is the time when they are, potentially, exposed to stomach and intestinal worms, also known as gut worms; lungworms; and liver fluke. While certain diagnostic tools are important, Donal says, so too is paying attention to the general condition of the animal.
Faecal egg counting is a ‘very useful diagnostic tool and does help inform dosing decisions’ but it is important to bear in mind that faecal egg counts are not as reliable in cattle as they are in sheep, according to Donal. “So, while a positive and a high worm egg count is very significant, a zero-egg count [in cattle] cannot be looked at in isolation without also looking at the clinical picture of the animal – that is, how the animal is performing and what it looks like,” Donal explains. Dung-sample tests, while also very useful, can return unreliable data, he says. Where dung sampling is carried out, particular attention must be paid to the condition of the animal, especially in relation to the detection of lungworms, rather than stomach or gut worms. “And the number-one sign that you need to be looking for here is coughing,” Donal explains.


“When you go out to feed your dairy calves, they will run up to the trough, and if they start coughing when they are running, that is the earliest sign that we are going to see a lungworm,” he says.
Regarding gut worms, the most typical sign of these is scour or diarrhoea, but also lack of thrive. He explains: “We would be expecting dairy calves to be putting on something in the order of .6kg per day – obviously that depends on the genetics of the cow. Your Holstein-Friesian would be aiming for a higher target weight than cross breeds, for example, and depending on the breed of suckler calves, we would be expecting a higher weight gain, per day. So, if we are not achieving that, we should be investigating it,” he says. 


Lack of thrive can also be attributed to coccidiosis, which, typically, occurs in housed animals. But, more frequently, Donal says, vets are seeing isolated cases of it in grazing animals of all ages, but particularly first-grazing animals.

Mineral issues

Mineral deficiency, too, can contribute to lack of thrive at this time of the year when animals are out on grass, says Donal. Knowledge of your grass composition is crucial, and knowledge of deficiencies, equally so.
Mineral deficiencies are caused by various things: geography, soil pH, the season, and so on. Copper deficiency is very common in Ireland, says Donal: “This can be made worse by antagonists of copper such as molybdenum, which is the most common one that we would be aware of.” This reduces absorption and utilisation of copper by the animal.
“Animals normally get their minerals from what they are eating, so a newborn calf, for example, is predominantly getting its minerals from milk, and as it gets older, it will start taking them from the forage or the grass they are eating, or whatever concentrate feeds they are eating.
“Depending on the part of the country you are in, the amount of minerals that are included in concentrate feeds might not be sufficient to feed the animal’s requirements. As vets and farmers, we know, in a particular [geographical] area, what we need to supplement. If that information isn’t available – if it is a new farm or there are new management practices – taking some blood samples to monitor mineral levels is a very good starting point,” he says.
Different forms of supplementation can be introduced in the event of copper deficiency, such as: concentrates; mineral drenches, which would be, typically, shorter-acting; mineral boluses, which would be longer-acting, lasting over a number of months and releasing a small amount of the mineral over the day. “These would probably be my preference, as they are the most reliable way of delivering minerals to animals,” says Donal.


Issues involving high levels of sulphur and iron are also of concern, Donal says, and there are telltale signs, in water, for the presence of both. “Typically, if you look at your drinking troughs, and if there are red and rusty stains, that tells you that you have high iron levels, which are likely to lead to problems. If you have high iron here, it is a good indication that you will have high iron levels in grass and silage also.”
The best physical indicator of sulphur is a smell, Donal says. “Water with a high sulphur content smells bad, like rotten eggs. So we can look at water and forage samples for mineral levels and address them accordingly.”

Looking ahead

Farmers have a wonderful opportunity now to plan for the months ahead, particularly in relation to housing and disease prevention, says Donal. And the main disease of concern here is pneumonia.
“Predominantly, that comes down to planning – how to manage the animals before they go into the shed and when they go into the shed, and also planning any changes to the sheds themselves.
“Ventilation is the biggest thing, we want to ensure that we have an adequate outlet and inlet for air movement in sheds. We all remember when we were trying to control the spread of Covid-19 in the human population, it was all about opening windows and ensuring there was ventilation and fresh air; well, it is exactly the same with cattle. If we can get better air movement in sheds, we would have far fewer problems with pneumonia.”

Preparing the animals

Donal, again, refers back to the management and treatment of Covid-19 when discussing how best to prepare animals for housing. Vaccination is the common denominator here, and now is the time to implement such a programme for your animals.
“If you are planning a vaccination programme, you should be starting it during the summer,” Donal says. Most vaccines work on the basis of a primary course followed by booster vaccinations – they require time to administer and become effective. Donal explains: “A typical vaccine – and there are variations of this – but a typical vaccine involves an injection now, followed by another one a month later, and then six-monthly, or annual boosters, after that. So, for example, I would be aiming to give the first injection in mid-July, then another in the middle of August and from then on, I have six months’ protection, depending on the vaccine, which is going to get me well over the housing period.”

Two birds

As discussed earlier, now is parasite-control time, so when the animals are in for their worm treatments, they should get their vaccinations, too. “From a management point of view, the cattle are in to be handled, and so you would try to get as many things as you can covered on the same day,” says Donal.

BVD eradication

In April this year, Minister for Agriculture, Food and the Marine, Charlie McConalogue confirmed the emergence of a small number of local clusters of bovine viral diarrhoea (BVD) infection, thought to have been spread between herds as a result of movement of animals, equipment and people. Subsequent reports indicated that, in 2023, the number of persistently infected (PI) calves had increased by about 20 per cent on 2022 levels. This may lead to continuation of the BVD Eradication Programme into 2024, despite hopes that this would be its final year. Donal explains that vaccination against BVD has never been more important.
“BVD survives in a population because of a carrier animal, or infected animals. In Ireland, we have done quite a good job of reducing the number of these but why, then, are we still seeing problems?
“When a disease is circulating within a herd, a certain amount of natural immunity develops. But when we don’t have BVD circulating within the herd, we don’t have any of this natural protection. If an animal comes into contact with the virus, then the whole herd is naive and it can become a big problem.

"Vaccinating for BVD has never been more important now. We want to make sure that we control any risk of spread from the small number of cases that we are seeing and that should be done by vaccination,” he says. A perception that vaccination is less important now is misguided.
And when is the best time to vaccinate? Donal explains: “BVD is spread by pregnant animals, that is a real risk period, so the ideal situation is that you vaccinate your breeding animals before breeding. There are two vaccines on the market, so you need to follow the guidelines for whichever one you are using.” Good housing management can also make a positive impact here, Donal says.

SCC mastitis

The latest Animal Health Ireland newsletter suggests that now is a good time to review herd performance in terms of animals’ somatic cell count. Donal advises dairy farmers to concentrate their milk recordings – ideally six in the year – on early lactation and late lactation but he agrees that now – mid lactation – is a good time to address any problems that exist in the herd so that drying off in the autumn will be straightforward.
“Mastitis and cell counts are some of the biggest drivers of profitability on farms and producing quality, safe food in a sustainable way. Typically, in Ireland we will dry off from October, into November or December and the cows are dried off for the two-month period to allow then to recoup, recover and prepare for having their calf and produce milk.
“Part of that involves controlling any underlying mastitis agents or pathogens that are in the herd at this stage. So, when we are looking now at any case of clinical mastitis we get, we want to identify, number one, what bacteria are causing the problem, and number two, what antibiotics would be best to treat it if there is a clinical case. Or, if we need to use treatment during the dry-cow period what is most appropriate on individual farms to control the specific problems they have.”
No longer is blanket dry-cow therapy practised so it hugely important to sustain the antibiotics that we have available to us, Donal says. “Prudent use of antibiotics is hugely important, it is all about using the right antibiotics, in the right amount, for the right amount of time,” he says. Mastitis management can be enhanced by ensuring that the milking machine has been serviced and is working properly, also.

Animal health plan

An animal-health plan is ever changing, Donal says: “Sure, the basics and benchmarks are in place but from year to year that plan must be revised and must be adaptable.”

Weather for worms

This summer’s extreme weather conditions have created optimal conditions for worms to develop and multiply more rapidly than normal, Donal says. “Following on from the warm weather and the rain we have had over the last few weeks, I am expecting that we will see problems with worms (in mid-July) as parasites thrive in these conditions.
“Worms would become an issue in sheep slightly earlier than they would in cattle and we have certainly been seeing the worm egg count in lambs, through dung sampling, climbing and we are putting interventions in place in sooner this year,” Donal says. This year has also seen an increase in the incidence of blowfly strike in sheep, too – not just in unshorn, upland animals.

Blowfly in dogs

Although a rare occurrence, Donal warns of the potential for the blowfly to strike on dogs if the conditions are right. “Typically, dogs that are very hairy, old, maybe not moving around as much, and might be wet, can attract the blowfly. If the environment is suitable, the maggots will develop on them,” he says.


Now is a suitable time to check herd fertility results and scans to see how the breeding season has gone on both dairy and suckler farms. “If it hasn’t gone as well as we would have liked, now is the time to investigate why that is the case,” Donal says.
“Frequently, in November and December we end up finding out that within the herd, there might be 15-20 per cent empties where the target would be somewhere around five per cent. Any diagnostic testing at that stage is somewhat limited because the problem has become a historical problem.
“If we investigate now, it allows the possibility of an intervention, perhaps to get in another breeding be it with AI or a stock bull. But investigating the problem much closer to the time that arises is far better than trying to investigate the problem down the road.”

Key pillars

There are four pillars of fertility: genetics, nutrition, management, and disease. “Genetics creates the potential, management realises the potential – nutrition comes in under this – and disease can destroy that potential,” Donal explains.
“We want to breed animals that are fertile; management involves getting cows right, getting heat detection right, using proper AI techniques, managing your stock bull; nutrition is all about having breeding cows in a positive energy balance – taking in more than they are putting out.
“Infectious diseases such as BVD, leptospirosis, IBR, any number of infectious diseases will adversely affect fertility. And any diseases that impacts temperature, for example, means a cow is less likely to be in calf.”

Relationship with vet

The importance of developing and maintaining a good relationship with your vet is emphasised by Donal. “The vet understands your farm and animals and can implement the preventative strategies and disease management required. While prevention is better than cure, absolutely as vets one of our biggest things is to be available to treat sick animals as required and we are proud that we are the only profession to provide an independent 24-hour service.”

Heat exhaustion – farm dogs

Donal advises caution around dogs working in extreme hot and humid conditions: “Sheepdogs, for example, are typically a darker colour and are more susceptible to heat exhasution. So, farmers need to remember to ensure that working dogs get a break, and have supplies of fresh water throughout the day, and shade in which to shelter from the sun.”