He was investigating a case of sudden death in a cow-calf herd. One cow and one calf had died very suddenly out of a group of 80 pairs on native grass.

Both the cow and calf were found dead right next to the dugout. The local veterinarian suspected blue-green algae toxicity, but we discussed several other causes of sudden death, including sulphate toxicity, nitrates, lead toxicity and anthrax.

Another cow-calf pair looked to be weak and wobbly, but they both improved without any treatment.

The producer wisely fenced off the dugout immediately so that the cows no longer had access to that water source.

The veterinarian had the producer submit a water sample to the veterinary diagnostic laboratory, and the results came back as positive for one of the two common toxins that are related to blue-green algae toxicity.

This toxic condition is actually caused by a bacteria known as cyanobacteria, which was previously known as blue-green algae.

The growth of these toxigenic cyanobacteria has also been termed freshwater harmful algal blooms (FHAB) and tends to occur when water temperatures are above 20 C and in relatively stagnant water sources.

Nutrient-rich water will support the growth of cyanobacteria, and so dugouts or other water sources that have runoff or soil erosion that allow fertilizer or manure to enter the water are more likely to have blue-green cyanobacteria growth.

When conditions are favourable, the bacteria can grow rapidly, doubling their numbers in one day or less.

The toxic blooms are very unpredictable and often do not last long. Cooler temperatures or heavy winds can inhibit growth or break up the blooms.

Blue-green algae blooms can appear as scum near the surface of the water. The water can be green, bluish or brownish-green in appearance and sometimes even red or yellow.

Once the cyanobacteria die, they may turn blue along the shoreline. It is also possible that the wind can concentrate the bacteria on one side of a body of water, making it more toxic for the animals that drink on that side.

The toxins produced by cyanobacteria are harmful to all animals and can affect cattle, horses, sheep and wildlife. They have almost immediate effects, and symptoms can occur within 20 minutes of ingestion of contaminated water.

They can affect the nervous system and damage the liver. Symptoms might include weakness, staggering, muscle tremors, convulsions and difficulty breathing.

If the cattle consume the toxin that causes liver damage, you might see longer-term effects, such as photosensitivity, or they may eventually die of liver damage.

The water from this dugout tested positive for anatoxin-A, which is one of the most rapid-acting cyanotoxins. It is rapidly absorbed, and clinical signs are almost immediate.

The cow and calf probably died very quickly from respiratory paralysis.

Unfortunately, there are also no obvious post-mortem lesions for veterinarians to diagnose in these types of deaths.

It’s important to differentiate blue-green algae blooms (cyanobacteria) from things such as duckweed or other filamentous algae.

If you’re not sure about the water source, you can take a picture and send it to a local livestock extension specialist, or you can take an approximately 100-millilitre sample of water and send it to the veterinary diagnostic laboratory for analysis. It’s probably best to freeze the water sample before submitting it to the lab.

Water contaminated with cyanobacteria can be treated with copper sulphate. You want to be careful and use only the recommended amounts for treating dugouts because too much can be harmful to beneficial organisms in the water.

It is usually recommended to not allow livestock to contact the water for approximately two weeks following treatment to allow all the toxins to dissipate.

Water quality is an important issue when the temperatures start to rise. In this case, it was blue-green algae, but we have seen similar sudden death scenarios with high-sulphate water sources causing polioencephalomalacia.

It’s important to monitor your water sources and work closely with your veterinarian to diagnose the cause of any sudden death cases.

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The study of genetic material from environmental samples has changed the way crops are bred, disease is addressed and animal genetics are understood.

In beef cattle, genomics research has started in disease diagnostics and the understanding of disease, bacteria and viruses.

Cheryl Waldner, a professor and researcher at the Western College of Veterinary Medicine at the University of Saskatchewan, is among those working on metagenomics research in beef cattle and is specifically looking into bovine respiratory disease.

Her work at the Livestock and Forage Centre of Excellence (LFCE) as part of the Canadian Cow-Calf Surveillance Network is a precursor to research enabled by new facilities at the U of S and LFCE.

Currently, in disease diagnostics, a sample undergoes a targeted test (most commonly, PCR) for a suspected disease. A PCR diagnosis detects specific genetic material such as DNA or RNA. However, it tests for one disease at a time.

“I can’t find a bug if I don’t know what I’m looking for most of the time,” Waldner told the LFCE 2025 Field Day. “I might stumble on it by accidental culture, but unless I’ve got a plan … they’re probably going to miss it.”

However, metagenomic sequencing can identify the known and unknown simultaneously and then provide the data for further analysis at any time.

Additionally, only one sample is necessary, and it doesn’t need to be stored for future testing, which reduces expensive long-term storage costs.

“It’s like if I had a book, and I was looking for specific words in a book, I might find those specific words (with the old tests),” she says.

“This is more like opening the book and actually reading the lines of the story, reading everything that’s there, and trying to figure out whether or not that’s relevant and whether or not there’s something that’s useful there.”

From a single sample that undergoes the metagenomic sequencing, Waldner is able to get information on respiratory disease, pinkeye bacteria and antimicrobial resistance.

One way Waldner is applying this research is by studying calves’ noses, which, constantly being at the business end of their herdmates, hold high amounts of bacteria.

Metagenomic sequencing has helped her learn more about respiratory disease pathogens because the process can provide new information on the pathogens that were previously hard to identify or learn more about.

The bacteria on a calf’s nose relates to the animal’s feces, which can be relevant for herd health and public health and surveillance. However, for Waldner’s research, it’s provided an “unprecedented look” at how things work from an antimicrobial resistance genetic perspective.

“It’s not just a gene in a sample,” she says. “It’s a gene in a sample, attached to a bacteria and attached to a whole bunch of other resistance genes — and oh, by the way, it’s attached to a suitcase or cassette or mobile genetic element that packages this stuff up all nice and neat and makes it extremely contagious. And we can see that when it’s there as well.”

In her research on respiratory disease, she’s been able to easily identify mycoplasma bovis as well as other mycoplasmas known to cause problems but for which there are no commercial diagnostic tests.

Using this research and metagenomics sequencing, Waldner is also looking into how to vaccinate calves for coronavirus as a respiratory disease, rather than just for scours. She says there is extremely strong evidence from one of her studies that coronavirus is linked to respiratory disease in calves.

She says a lot of the virus is in calves, but in cow-calf herds there are virtually no antimicrobial resistance genes when looking at respiratory pathogens through genomic sequencing or traditional measuring methods. This means the possibility of vaccination and successful treatment is high.

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Deanne Fulawka, a researcher from the University of Manitoba, presented her team’s findings at the Manitoba Sustainable Protein Research Symposium in Winnipeg July 7.

A main point of the study was to get local projections on how implants could impact emissions on Canadian cow-calf operations.

The study modelled scenarios for 130 calves. Under the simulated exercise, calves would have received hormonal implants at 30 days old. Results were then compared with 130 simulated unimplanted calves.

Local farm conditions across south-central, southwestern and Parkland regions of the province were plugged into the model. Fulawka’s team estimated greenhouse gas emissions for the three regions using Agriculture and Agri-Food Canada’s Holos model.

Ammonia projections were based on simulated manure outputs using Canadian research on beef feed intake, manure practices, body weight and temperature. Regional crop yields, estimated dry matter intake and water needs were taken into account.

The hypothetical revenue producers would get from those cattle was based on prices at local auction marts.

Numbers for birth and weaning weights and average daily gain were based on a 2015 South Dakota State University study, which used Angus and Angus-Limousin cross bull calves. It found that when calves born in March and April received their implants in May, their weaning weight increased by an average of 29 pounds compared to untreated calves. The calves from mature cows gained more than calves from younger cows.

Based on a price of $616 per hundredweight, the Manitoba study estimated that revenue at weaning for its hypothetical calves was $135.80 greater per implanted calf compared to untreated calves.

Total emissions were similar between implanted and non-implanted calves. For example, ammonia emissions for implanted calves were only 0.04 per cent lower.

However, due to the higher weight of implanted calves, the greenhouse gas intensity, measured as kilograms of carbon dioxide equivalent per kilogram of live weight was 3.72 per cent lower when implants were used.

Implants didn’t change how much land was needed for production of feed (including pasture) or water. Again, however, landuse intensity (hectare per kilogram of live weight) and water use (litre per kilogram of live weight) decreased by 3.92 per cent due to higher live weight when calves were marketed.

“There is an economic benefit to the producer, but we also want to send home that message that there is also environmental impact,” said Fulawka.

Fulawka noted that South Dakota researchers compared calves implanted at 30 days to calves implanted at weaning, which is when many producers would be implanting their calves. They found that later-implanted calves caught up to those implanted at 30 days and finished at similar weights.

She said Canadian beef producers have set a goal to reduce emissions, adding that every best management practice that is added will get the sector closer to that goal.

The Canadian Cattle Association has set a target to reduce primary production greenhouse gas emission intensity by 33 per cent by 2030, according to its website.

It’s estimated that fewer than 30 per cent of producers in the cow-calf sector use implants, which makes this an area of significant opportunity to improve economic and environmental outcomes, Fulawka’s report said.

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The good news is, we can test for the usual cattle parasites — and if thresholds are passed, then those herds or pens are treated.

Work done a few years ago by a pharmaceutical company with which I was involved found that we could put most beef herds into low, medium and high categories for internal worms, and only the medium and high herds would need to be dewormed.

The best time to check is after cattle have been on grassy pasture later in the summer when burdens increase.

Cattle are generally pretty low shedders of eggs because of low infestation, but late summer is the best time to check. Yearlings generally have higher counts, followed by calves. The cows are most resistant.

Fresh manure is needed when doing a manure test. The modified Wisconsin test is the most accurate test for cattle.

It’s possible to pool samples instead of doing a group of 10. This should save time and money and be just as accurate if done properly. This should save the clinic time.

We all need to test more before treating the entire herd.

Managing ivermectin resistance

It has been found that ivermectin resistance is increasing, which reduces effectiveness. Resistance varies greatly from herd to herd.

Check to see if your herd veterinarian does parasite testing in-house, at their clinic, or sends them out.

The problem here is the number of tests that are needed as well as the cost and time.

Some producers complain about spending money on tests, only to have to deworm the herd anyway. Their response is that they might as well have just dewormed them in the first place.

This response is understandable, and quicker chute-side tests need to be developed to reduce this problem. I am sure some researcher will develop a quick, lower-cost method.

Another class of parasite treatment is the benzimidazoles, including products such as Safeguard and Valbazen. The problem is that only internal worms are treated, and the products don’t include treatment for lice.

Until the last decade or so, ivermectin products accomplished both parasite and lice control. They came on the market when my generation of veterinarians (baby boomers) were practicing, and everything was treated.

Lice were most visible, while internal worms rarely got bad enough in Canada to cause outward clinical disease.

However, this is changing.

Now, veterinarians must help producers fine-tune their entire parasite treatment program as well as their fly control program.

Internal parasites, such as liver flukes, and external ones, such as ticks, may also be showing up in slightly increasing frequency.

These parasite problems are in more specific geographic regions, and they can have complicated life cycles, so they may even show up in specific years under specific conditions.

Again, your herd veterinarian can help with specific treatments and monitoring if either liver flukes or ticks become prevalent in your area.

Fly control

For fly control, there are fewer and fewer products to use, and they are all similar chemically with no new ones on the horizon. Many have actually been taken away from us.

Treatments must be used only when fly numbers get high enough. If oilers are used, they can only be charged with product when necessary. This saves product and cost and slows down the development of resistance.

Canadian winter slows down the transmission of internal parasites, killing the eggs and reducing the survivability of larvae.

Rotational grazing, with a long time between pastures, allows more larvae to desiccate and die.

Producers should be able to keep parasites in check with selective and timely use of products, specific management changes and checking for eggs in the manure. It might also be a good idea to cull cows that are identified as lice carriers.

Parasites evolve and have been survivors, which means constant research is needed in this field so we are aware of new developments and products.

Most research is species-specific, but transmission can occur between similar species, such as bison and cattle or horses and donkeys.

Ticks, on the other hand, can involve several different species in their life cycle, as do liver flukes.

It’s a complicated world when it comes to parasite management, and herd management needs to be reviewed from time to time.

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Looking at survey data over the past 30 years, there has been a trend, at least in Western Canada, with producers transitioning from late winter/early spring calving in February and March to later calving in April, May or June. Whether producers are thinking about making a shift in timing or simply reassessing their decisions to calve when they do, they should think about the risks and rewards of timing their most critical phase in cow-calf operations. What are the advantages or disadvantages of keeping the same season? What are the greatest challenges during calving on my farm and how can I manage them? What are the benefits of my existing calving season, and what are the drawbacks? How much labour do I need and how much do I have to get the job done?

The following producers have done their homework and planned ahead before shifting their seasons back or ahead to meet the needs of their particular farms and families.

Late summer/fall calving: Taralea Simpson, Portage la Prairie, Man.

Taralea Simpson has been calving her Simmental/Angus commercial cow herd in August and September for many years. Growing up, her family traditionally calved during January and February.

“I did that for a long time on my own and there was always something going wrong,” Simpson says, adding that scours, frozen ears and sleep deprivation made for some challenging winter calving seasons.

In addition to raising cattle, Simpson works as an agronomist, which also played a role in her decision to opt for a later calving program. “I decided to switch to the fall; I’m not as busy with work, I have more time to make sure everyone is doing OK,” she explains. The herd is cleaner and has fewer health issues, she adds.

Simpson’s farm is set up for rotational grazing and her calving pasture is right close at home. She checks calving cows daily to make sure there aren’t any problems but notes that she rarely has issues with dystocia.

“The calves might be a bit smaller but you are kind of selecting for that, you want calving ease on the pasture,” she explains. She notes calving ease on her farm has generally improved over time, because over the years she has been retaining heifers from cows that are calving easily out on the pasture.

Catching newborn calves early for processing is key. “Fall calves tend to be like deer and the cows hide them,” Simpson says. “I try to do my very best to tackle them within the first day or two for castration, sneak up on them when mom’s not around.”

That approach works 80 per cent of the time, she adds, and she processes the remaining few when cows and calves start coming back to the yard when the snow flies.

“Your feed consumption is higher; those calves are 250 lbs. right now and in another couple months they are 350 to 400 lbs. and eating a third as much as their mother,” she says. “You do use a lot more hay through winter than those cows that are coasting through the winter and calving in spring.” She has an area set up with calf panels and provides calves with their own bale of hay and a bit of grain for which they don’t have to compete with the cows.

The calves stay on their mothers through winter and Simpson typically weans and ships them directly to market in the first two weeks of May.

When it comes to breeding, Simpson says conception rates are similar to what they were during earlier calving; however, snowy weather can impact bulls’ ability to breed. “Out on the pasture, the bulls have good traction and they can get things done before it gets snowy and slippery,” she says.

Late winter/early spring calving: Randi Wenzel, Central Butte, Sask.

Randi Wenzel and her family operate a large, mixed commercial cattle and cropping farm in south-central Saskatchewan. They used to calve from mid-March until mid-May or later, but as their farm continues to evolve, they are looking toward transitioning to an earlier, more condensed season that starts in February.

“Due to the fact that we are a mixed operation and the grain side is getting to be pretty big, I’m trying to move calving up,” says Wenzel, who also works full time as an agrologist. Her busy off-farm work season hits in April and May, the same time the family is planting crops at home. She prefers having most cows calved out before they get busy in the full swing of seeding.

“By taking another 20 days out of our breeding cycle, we can get everything processed and shipped to pasture by the last week in April,” she explains.

READ MORE: Tightening the calving season

Wenzel says preparation and proper facilities are key when calving in the winter. While the weather can be cold in February, she adds that calving in April in their area, when the wind picks up and spring blizzards hit, can take a toll as well.

“Overall February conditions have been fairly decent,” she says, noting they built a calving barn about three years ago to help offset the risk of unpredictable weather. They have been surprised by the occasional early arrival or set of twins but have found calving cameras are a useful monitoring tool and have helped the family save calves.

They have cameras installed in their barn as well as outside to help them keep a close eye on calving cows and newborns, but Wenzel cautions it’s best to use them in combination with walking the pens.

Moving up the breeding season a few days has not been a challenge for the cows to adjust. “They adjusted pretty well, and if they aren’t in season they are culled,” Wenzel says.

They typically wean and sell calves at the beginning of November, again timing those events around harvesting and other fall farm work such as spraying. They’ve also noticed their calves are bigger now at shipping time than before.

“We’ve changed up our herd sires and are being a little more aggressive on that,” Wenzel says, adding that earlier calving is likely a factor as well.

Late spring/early summer calving: Jason and Karla Hicks, Parkbeg, Sask.

Jason and Karla Hicks and their family operate Bluestone Stock Farms, a large Angus operation. They shifted away from winter calving to a later season, May and June, and maintain a defined breeding season of 60 days.

“Our commercial cows used to calve at the end of March and April, and we always get snow in April and don’t have anywhere to put large numbers, so we went a month later to miss those snowstorms,” Jason explains. “There’s less death loss, less work.”

“Calving in summer is easier on the marriage,” Karla adds.

The family was awarded Saskatchewan’s TESA (The Environmental Stewardship Award) in 2015, and summer calving has become a complementary fit with their stewardship principles.

“Now we calve out on grass, in rolling hills, coulees, trees. It’s set up naturally to be good calving grounds,” Jason says.

They calve bred heifers as well as earlier-bred community pasture cows and some purebreds slightly earlier than the main herd, in a field closer to the yard.

“This way you eliminate issues of pen calving, don’t have scours issues, and we think our heifers mother up a bit better this way,” Jason says. The weather can still be unpredictable, however. “Out in the open, when the heifers are calving, in April you do get a snowstorm,” Jason says.

They’ve noticed, since their transition, that they’ve had fewer calving problems. “There has been natural selection for that over time, for the entire herd,” Jason notes.

One downside of pasture calving has been predator attacks. Their ranch is natural terrain for coyotes and cougars, which has resulted in losses in the field and even in their corrals. “We have a huge coyote population,” says Jason. “Even 15 years ago we had coyotes take down yearlings right in the feedlot.”

After calving, they will brand, castrate, vaccinate and tag calves in four or five branding days in July. Later, they wean calves from mid- to late November.

“Our weaning weights didn’t change that much,” says Karla, after they backed calving off. “We didn’t change the bulls we bought or the type of cow we had. When those calves are born in nice weather, they hit the ground running and start growing,” she explains, adding that winter-born calves use a lot of energy just to keep a calf warm.

As groups of calves are weaned, they are sorted and backgrounded, in an effort to avoid selling in the fall when the majority of calves hit the marketplace. They watch markets closely and will sell their commercial calves anytime after weaning through to the following August after grassing them as yearlings in the summer.

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While there are a couple of vaccines licensed for cattle, they do require multiple shots. Vaccines help, but focusing on decreasing stress and other diseases can limit mycoplasma infection.

Mycoplasma comes in many clinical forms but in feedlots we mainly see it in respiratory problems and in joints.

The respiratory problem is often indistinguishable from other common causes of pneumonia in the feedlot and the joint form can be very similar to histophilus abscesses.

Mycoplasma commonly plays some role, and it can be confirmed for chronic cases in feedlots with lab tests to verify veterinarian diagnosis.

A decision tree needs to be established early in the case to guide decisions to treat, ship or euthanize, for the welfare of the calf, if the case becomes clinical.

These cases cost the feedlot industry millions of dollars in treatment and labour costs, as well as in deaths and chronically ill animals that need to be euthanized. It’s not a fun disease to deal with.

Prevention

With mycoplasma, we need to really, unequivocally, concentrate on prevention.

Even though a few antibiotics have indications for mycoplasma on the label, those are more for metaphylactic treatment and use when exposure is imminent.

It is believed that after a few weeks in the feedlot pretty much all calves are infected (that is, have been exposed and are carrying the organism) yet in well-managed yards where preimmunized and preconditioned (weaned already) calves are purchased, the incidence can be kept to a minimum.

In cattle, mycoplasma is a secondary invader, meaning in the case of respiratory disease it often comes in secondary to the viral pathogens, especially IBR (infectious bovine rhinotracheitis). Other respiratory bacteria such as mannheimia, pasteurella or histophilus can also get established and set the lungs up for the invasion of mycoplasma later in the course of the disease.

A good number of these infections may then spread to the joints. Once in the joints, especially if more than one joint is involved, chances of recovery are slim to none. They then become an animal welfare issue and often cost lots of money in antibiotics, painkillers and other medications before a decision is made to euthanize.

In the bison industry, mycoplasma is almost always a primary pathogen and can cause considerable death loss in naïve populations of calves, cows and bulls. There appears to be immunity established once the disease goes through, but death losses can get quite high on initial exposure. Some bison feedlots live with a low percentage of it and ideally try to have their calves come in with maximal respiratory protection to minimize its severity.

Even though it seems primary in bison, by keeping lung health as high as possible, severity and incidence seems to be reduced. Bison cow-calf herds that have had bad outbreaks seem to be free of cases going forward, which to me means natural immunity is developed.

Stress

Anything then that reduces stress, and/or reduces the likelihood of the other respiratory bugs, theoretically should reduce the incidence of mycoplasma pneumonia.

Currently two mycoplasma vaccines on the market appear to have good efficacy, but here’s the kicker: they need an initial shot and either one or two booster shots essentially before the chance of exposure.

Feedlots that have a decent infection rate would need to know where they are sourcing their cattle and have them preimmunized before coming to the feedlot. Perhaps the original vaccination for mycoplasma done on the farm, then boostered at the feedlot, will help some.

We as veterinarians always talk about reducing stress. Transportation, processing, weather conditions, parasites, exposure to other cattle and co-mingling all play a role in determining whether calves will get sick.

We have direct control of preimmunization as cow-calf producers. The feedlots then can ask for preimmunized calves. The vast majority of calves are vaccinated in Canada these days for most of the major respiratory pathogens, as well as clostridial protection. The question then is, for which diseases do we pre-immunize? Cow-calf producers are vaccinating their calves younger and reap the benefits of having fewer calves get sick on summer pasture. If the boosters are then given at weaning, we should, in theory, have less respiratory disease.

If we can avoid unnecessary transportation stress by selling directly to feedlots through satellite or online sales, one transportation session is eliminated, and cattle go directly from the source to the feedlot. Distance transported is not as significant as the stress to calves of being loaded and unloaded multiple couple times.

Less sickness and stress lead to less mycoplasma, so it is prudent to use treatments that help calves manage their stressors. Various electrolyte formulations such as Destress have been tried to minimize shrink. Products such as probiotics yield fewer digestive upsets as well.

All these preventive measures ultimately lead to less respiratory disease and less mycoplasma pneumonia or joint infections. With more collaboration between the cow-calf sector (first line of defence), trucker (second line of defence), backgrounder (third line of defence) and feedlot owner (last line of defence) we can all do our part to protect these valuable cattle. Again, owners who calve, wean and raise their own seldom have severe respiratory issues, especially mycoplasma.

We may not ever eliminate mycoplasma but at least we can keep it at bay by the best prevention strategies we know: good husbandry and minimizing stress as much as possible.

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Even good teenagers can be expensive. In our beef cattle production systems, the teenage role is filled by replacement heifers, and like teenagers a bit of understanding about the changes they are going through over those years can help improve the outcomes when we deal with them.

Whether we appreciate it or not, cow depreciation is a massive expense in most cow-calf operations. In many cases, it ranks as one of the top three expenses. Depreciation does not occur in a linear fashion with replacement heifers. Because there is a big upfront cost in either purchase or development, there can be a subsequent large depreciation cost for heifers that leave the herd early in life.

Understanding the basic physiology occurring over the roughly three-year time frame from heifer calf to second-calver can help us to manage this process, our expectations and the resulting cost to our operation. The first thing young heifers are going through is as basic as growth and puberty.

Estrus occurs based on a combination of age and weight/body condition. This means older heifers (those born in the first cycle) have a bit more time to reach the milestones required for ovulation and getting bred in the replacement program. If we expect our replacement heifers to calve at two years of age, they must be bred at 15 months of age.

If we look at a group of heifers born over the span of a 90-day calving season, when the oldest heifers are 15 months old, the youngest are 13 months and may not have even reached a physiological stage where estrus is possible. If we breed early to calve heifers ahead of the main cow herd, this may be exaggerated further. Heifers are less likely to be bred on their first ovulation than on subsequent ovulations, as the hormonal process of ovulation helps with reproductive organ development. For the best success, breeding heifers should be on their second or further ovulation by the time breeding season rolls around.

Traditional knowledge dictates that heifers should be roughly two-thirds of their mature size at first breeding. A lot of research indicates this is not necessarily true and that healthy heifers at 50 to 55 per cent of mature weight at breeding will perform as well and last as long in the cowherd as heifers exposed at a heavier weight range.

To put this in perspective, the two-thirds rule means that you expect an 850-pound breeding heifer to mature into a 1,300-pound cow. Managing to a lower ratio may allow us to reduce development costs and results in smaller mature size. Breeding success is higher when heifers are on a rising plane of nutrition through the breeding season.

If a heifer is not bred and but is still gaining weight over the summer, they are adding value and not taking a depreciation hit (market dependent). From a physiological perspective, a first- or second-trimester bred heifer does not take a lot of extra energy and basically just needs to keep growing and maturing. At this stage, the fetus is quite small and does not demand a lot of excess energy.

Most critical time

In the third trimester the heifer starts to have additional requirements as the fetus develops, her mammary system is starting to come to life and she continues to grow. This leads to the start of what’s likely the most critical time physiologically in her entire life — and is directly connected to the largest potential depreciation hit in a cow’s lifetime.

Firstly, the heifer must calve, and recover from that calving event. This includes basic repair of the reproductive tract. Even a normal unassisted birth will result in some trauma to that tract. However, a difficult birth may result in further damage that requires significantly more biological resources and time for the heifer to repair. Difficult births are one of the leading causes for heifers to fail at rebreeding. Additional physiological changes include milk production and raising a calf. More on that in a bit.

That first-calf heifer is also not yet at full mature size and still has some further growth of her own before she gets to that final mature size. Another interesting part of her development also occurs around the age of two. At roughly this stage of life, she replaces her incisors with a set of permanent incisors.

If our heifer calves at 24 months of age and we want her to calve again at three years old, she needs to rebreed at 27 months of age, or roughly 90 days post-partum. To obtain good conception rates, heifers should be happy, healthy and on a rising plane of nutrition. Physiologically, her body needs to tell her life is good, her nutritional needs are supported, her calf is supported and there are enough extra resources to support a pregnancy. This three-month time frame for rebreeding also roughly coincides with peak lactation, which can easily see a 20 to 30 per cent increase in nutrition requirements.

In a nutshell, physiologically we are asking that the first-calf heifer recover from calving, continue to grow, learn to be a mother, develop/maintain peak lactation, and rebreed while she may be between sets of teeth.

In a physiological context, it is readily apparent that it is much more difficult to get a first-calf heifer rebred than it is to breed a virgin heifer. It is also where we see the highest depreciation rates, as an open three-year-old generally has a massive value difference when compared to a bred three-year-old or a bred heifer. We also have not had enough calves from that female to cover the development costs or purchase price.

No matter how you slice it, teenagers can be challenging. Understanding this can help us in our operation to decide what extra support to provide to these cattle (or whether to provide extra support) or if we should own these young cattle in the first place or examine alternative replacement strategies.

If your ranch pregnancy checks or markets open cows, it may be worth tracking the percentage of first calf heifers that wind up on the truck heading into their third year. It may help you adjust management to reduce the depreciation costs associated with cows that take an early exit from the herd. Because the depreciation cost is so high, there may be cheaper alternatives providing further support to that specific set of animals as they grow through those teenage years.

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I know one must spend their time wisely at calving season, but even just keeping a cow-calf pair in isolation a bit longer may be all that is needed to secure the health of sa calf. Let’s look at few situations.

We all know the value of extra time spent making sure calves suck in order to get the precious colostrum, or making sure they are well bedded to prevent pneumonia, or having the calving area clean to prevent scours. These are all measures worth the extra effort. More live, better-doing calves result.

You might also identify calves that may need a little more individual care early in life to make sure they get a good start. Larger, heavier birthweight calves are always slower to rise, and spending more time lying down can lead to developing an infection known as navel ill.

These bigger calves often are also the ones with slightly contracted tendons or legs that are rotated in or out, making it difficult to walk. Their tendons need to be stretched. To speed the process, calves can be given painkillers before applying some forceful stretching. One can also trim or rasp down the end of the toes to avoid knuckling of the foot. Trimming the hoof makes it easier for the calf to bear weight on the toes, which starts their own tendon-stretching process. Make sure calves so affected don’t need to walk too far to keep up with their mothers, as this is very tiring.

Calves are inquisitive, so make sure there isn’t plastic blowing through the pen or baler twine for them to chew on and swallow. These “software” products can cause problems such as gut blockages or indigestion. Minor issues such as ear infections can lead to pneumonias or head tilts, and antimicrobials at the right time may rectify this.

What’s causing lameness?

Much lameness in calves may be due to minor sprains or strains, but it’s worth checking their feet and legs if they are very lame. It could be due to anything from stepping on a rock or uneven surface, something imbedded in the bottom of the foot or even a broken leg. Treating them quickly can get them on the road to recovery.

If there is a break, lower-limb breaks can be cast successfully with a three- to four-week healing time. Higher-limb breaks may require a specific type of splint but very few are untreatable. It is important to get them checked out and attended to.

A producer might often find a calf that is gaunt and a bit dehydrated. It can be a bit hard to determine if this is a calf or cow issue, but regardless, the calf needs nourishment with either milk replacer or high-energy electrolytes.

As part of the treatment, have a close look at the calf to see if there is an underlying cause to decreased appetite, such as a low-grade navel infection, pneumonia or perhaps scours just starting. Each of these conditions generally comes with a different treatment plan.

On the other hand, the calf’s issue could be related to the cow. She could be sick from mastitis or a uterine infection (from being slow to lose her placenta). This hurts milk production and the calf suffers. Some cows have extremely hard teats that don’t release milk. If you have what appears as a starving calf, please check the cow’s udder.

Coming across a down cow is an obvious sign there is something wrong. It could be a veterinary emergency to determine the cause, so act quickly. No one likes seeing a cow down for any period — the longer they are down, the harder to get them up, even with treatment. Make sure they are on a well-bedded area and get the proper diagnosis and treatment plan. If a calcium, phosphorus or magnesium problem is identified in one cow, it may indicate others in the herd. Preventative measures can be taken for the rest.

Don’t assume anything

Calves that fail to thrive could lack colostrum but often other factors may be at play . I have seen calves affected by everything from a congenital heart problem, to a cleft palate, to being born with no rectum to part of their intestinal tract missing. These may go undetected for a few days and often there is very little we can do. I have often attempted surgery on those without a rectum, for example, sometimes successfully, sometimes not. It depends on several factors, but again, with many of these congenital defects, some can be fixed either temporarily or permanently. They are often very rewarding cases if the surgery works.

All these affected calves often need a few days with their mothers in a private pen. Disinfect the pen between uses and especially if the ailment is potentially contagious.

Let’s hope this extra care and attention can save you a few more calves that go on to be sold or raised to slaughter weight.

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Dr. Steve Hendrick of Coaldale Veterinary Clinic, a feedlot, dairy and cow-calf practice in southern Alberta, sees quite a few cases of diphtheria in cow-calf operations and in feedlots. “It’s not something we deal with every day, but it happens fairly frequently, and today there are some better ways to treat severe cases,” he says.

Causes

“We think trauma (to the throat) opens the way for the infection and inflammation, such as eating abrasive feeds,” says Hendrick. Trauma could also be caused by using a tube feeder on baby calves. “If the surface of that tube is rough (somehow damaged or was chewed on), or is forced abruptly into the throat, it may scrape or irritate the larynx.”

The infection is generally caused by pathogens in the environment. They simply need an opportunity to invade the tissues. The main ‘bug’ that causes diphtheria is Fusobacterium necrophorum, which is the same one that causes foot rot and liver abscesses and is often found in the gut and upper respiratory tract, says Hendrick.

“We suspect viruses such as IBR can play a role because they can damage the lining of the respiratory tract and open the way for bacterial infection,” he says. “In feedlots we often see diphtheria in conjunction with histophilosis.”

Histophilus somni is a bacterium that lives in the nasal passages of cattle and sometimes causes an acute, often fatal, septicemic disease, especially if it becomes complicated with other infectious agents (viruses or bacteria).

Symptoms

Due to swelling in the larynx (which narrows the opening), the calf has to make more effort for every breath. Hendrick says air must pass those swollen folds, so they are also constantly getting more irritated with each breath, rubbing against each other.

You may hear the calf wheezing. At first you may think it’s pneumonia because he’s struggling for breath, but if you observe the respiratory effort you can tell the difference. A calf with pneumonia has trouble pushing air out of damaged lungs, whereas a calf with diphtheria makes more effort to draw the air in through the narrowed airway.

A calf with diphtheria often drools frothy saliva because he has trouble swallowing — saliva may continually drip from his mouth. “He’s so busy trying to breathe that he can’t take time to swallow,” says Hendrick. “Extra salivation can also be due to irritation from sores in the mouth as well as the throat.”

Sometimes the infection is in the mouth and not in the throat, and that’s not as much problem for the calf because he can still breathe.

The larynx area serves as a valve, sending food down the esophagus and air down the windpipe.

“Most of the time you are just breathing; the valve only closes off the airway when you swallow,” Hendrick says. “When the calf has trouble breathing he doesn’t take time to swallow.”

If swelling in the throat closes the airway, the calf suffocates. If it is wheezing and struggling for breath, staggering from lack of oxygen, it becomes an emergency. You need to slice through the windpipe below the larynx (carefully cutting between the ribs of cartilage surrounding the windpipe with a clean, sharp knife) for the calf to breathe through.

Diphtheria is most common in calves, but older animals are sometimes affected. However, a mature animal has a larger throat and windpipe and may not have as much trouble breathing if this area becomes swollen. “The infection may still affect the larynx and in some cases may cause enough scar tissue in the vocal folds to affect the voice,” says Hendrick. Some cows lose their voice and can’t bawl as loudly anymore.

Treatment

Hendrick says infection in the larynx is generally responsive to oxytetracycline — this antibiotic has good distribution throughout the body. “We also have good luck with penicillin. Some people prefer to use the newer, longer-lasting drugs because they don’t need to treat as often, but oxytet or penicillin work well.”

There are several antibiotics that can be used. Your choice may depend on your ability to catch the calf, especially if repeat treatments are needed.

Sometimes it may take as much as a month of treatment to get a calf over this problem, but there’s a way to help those persistent serious cases.

“A tracheostomy insert can bypass the swollen, irritated larynx and allow the calf to breathe through a hole in his windpipe,” says Hendrick. “Your veterinarian can place it into the calf’s windpipe below the larynx. We have great success with this, in baby calves and in feedlot calves.

There are a number of non-steroidal anti-inflammatory drugs that can also be used. It is important to discuss this with your veterinarian and treat the calf as soon as you realize he has a problem.

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Or a calf may suddenly become dull and bloated. In either case, these calves were happy and healthy right up until the acute infection started creating toxins. One theory is that the multiplying bacteria start to damage the gut and it shuts down, perhaps causing a sudden buildup of gas in a certain area, and hence the acute pain. If the calf is not treated immediately, toxins leak through the damaged gut wall and into the bloodstream to create toxemia — toxins throughout the body that start attacking various body organs. The calf goes into shock and soon dies unless this condition can be reversed by appropriate treatment, including IV fluids.

Usually the calf does not have diarrhea. This infection comes on so quickly that the gut shuts down before the calf scours. There are several types of infections that can affect the gut this quickly, and the most common was Clostridium perfringens before the advent of vaccine for types C and D.

This serious disease has been called enterotoxemia, overeating disease, purple gut, toxic gut, and other names. Dr. Lee Meyring, a veterinarian near Steamboat Springs, Colorado, says clostridial organisms are a very diverse group of bacteria.

“We have good vaccines for some, and yet there are many herds that still battle this type of gut infection in calves,” says Meyring. “One of the different genotypes may be the more prevalent problem in those herds and we have to come up with a different program to try to prevent it.”

Along with a vaccine for C. perfingens Type A bacteria, there are also some treatments that work. If a calf can be treated early — at the first signs of acute gut pain or bloat — there is a chance of saving that calf. The infection can be halted with the proper antibiotic, and a shut down gut can be stimulated with castor oil to start things moving through again. Once toxins get into the bloodstream, however, the calf quickly goes into shock and internal organs begin to shut down. At that point it’s more challenging to save the calf.

Meyring’s first approach if dealing with Clostridium perfringens type C or D is to give the calf antitoxin either administered orally or through IV Banamine also helps reduce the inflammatory reaction and eases pain.

“If a calf is bloated, I usually give some oil, to help get things moving through — if he’s not so ‘full’ that there’s no room for the oil,” says Meyring. “Oil has a laxative effect to get those toxins out of there.”

Castor oil works better than mineral oil, partly because you don’t need as much volume (plus if the calf is already bloated and full) and it also stimulates the gut to move. Mineral oil merely works as a lubricant. The usual dose for castor oil is two to three ounces for a small calf, up to five to six ounces for a big two- to three-months-old calf. You can’t really overdose on castor oil, and it may save him — by absorbing some of the toxins and stimulating the shut-down gut to move things on through.

Some calves are severely bloated, and some just have extreme gut pain without bloating.

“It would be interesting to culture the organisms and find out exactly what you are dealing with,” says Meyring. “Some of these bacteria are tremendous gas-producers and some less, and this may be part of the difference.” Regardless, the castor oil stimulates things to move through.

If the calf goes into shock, however, the only chance is to give large amounts of IV fluids along with medication to combat shock. If you can reverse shock before vital organs are completely shut down or seriously damaged, the calf may survive. If organs have shut down, you are too late. If you can reverse shock, however, and get enough fluid into the circulatory system to get the kidneys working, passing urine, the calf has a chance.

Prevention is the best path, if you can do it, and close monitoring of calves to notice any cases very early on — before they go into shock or you find them dead.

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