Over the last four-to-five years around this time of year, I’ve seen an increase in cases of cows eating stones. This condition called pica is not just cows eating stones, but plastic, timber, feasting in ditches and chewing on the bark of trees. So why have we seen an increase and is this perceived increase real?
My own opinion is that it definitely is an emerging problem on some dairy farms. Interestingly, last summer I saw very few cases during the warm, dry summer months. In the last week, I spoke with two farmers who had what could be considered suspect cases. I also spoke to a farmer in early February who had yearling heifers eating gravel and stones.
Causes
You can always have an occasional cow or a couple of cows doing this, but what I’m seeing is a significant percentage of herds affected, with some of the herds I’ve seen having over 10% of cows affected. There are a number of theories around why this pica or depraved appetite may occur. I’ve settled on two main ones because of the time of year we generally see it.
Phosphorus is a key element in plant growth and also in the cow’s physiology
The first cause of pica I have diagnosed in several herds is due to a phosphorous (P) deficiency. Phosphorus is a key element in plant growth and also in the cow’s physiology. It is critical in bone growth, enzymes, energy conversion and protein digestion in the rumen.
The second cause I have encountered is due to low energy to protein ratio in early spring. This can usually be compounded by spring grass low in fibre. This fast-growing, leafy spring grass can affect the rumen function in cows in some cases. The lack of fibre can particularly affect rumen function. This type of sub-acute ruminal acidosis (SARA)can affect cows’ grazing habits, leading them to seek out more unpleasant things to consume.From what I have seen personally, adding some fibre into the diet of these herds leads to a big improvement.
Low sodium has also been theorised as a cause but I’ve yet to see this in grazing cows, more commonly encountering it indoors. A very easy way to rule this out is to add cheap salt blocks in buckets at grass.
If cows are deficient they will consume the salt and stop this behaviour. Salt is the only mineral that cows self-regulate, meaning they will only seek it out when they are deficient and need to.
What you can do
I think supplementing blind is not ideal. Why? Because of the complex mineral interactions and the chance of something else being wrong. Your vet, nutritionist or adviser will be able to look from the outside-in.
Rumen health and energy or protein issues can be observed by looking at protein to butterfat ratios, as well as yields and cow performance
The best way to diagnose a phosphorous deficiency is through careful on-farm history and blood testing a cohort of affected animals. Your vet can do this blood test on between 8-10 animals looking at blood levels.
The herd history is very important also, looking at P indexes on-farm. Low P indexes, with the history of pica, always make me suspicious of phosphorous problems.
Rumen health and energy or protein issues can be observed by looking at protein to butterfat ratios, as well as yields and cow performance. I think examining the faeces of cows is useful, while we would expect them to be loose, we don’t want green watery scours. This problem will often resolve itself over time or else with the supplementation of fibre in the diet. This is a very brief overview and obviously requires more in-depth analysis to find farm-specific solutions. Remember, there are other reasons for cows to be scouring and they should always be investigated.
Phosphorous supplementation
On many of the farms we investigated through blood sampling, we found low phosphorus percentages in the animals examined. Carefully choosing the cows to sample was critical, taking down tag numbers of cows chewing stones or showing signs of pica greatly helped identify the problem.
Short-term plans involved supplementing phosphorous through meal, water or other sources
Next, we made a diagnosis and drew up short-term plans and more importantly long-term farm specific plans.
Short-term plans involved supplementing phosphorous through meal, water or other sources. If feeding concentrates, then a lot of mills can add P to concentrates, looking at daily requirements of 0.4% of DM intake, or a cow’s daily requirement of around 70g of P a day. If going by water, I have found that working out requirements and supplementing up to 3-4 weeks during risk periods made a difference.
My own personal experience is that supplementation for less than two weeks does not significantly affect clinical signs. Of course, this can be farm-specific depending on the severity of the problem, source of P and blood results.
As lactation progresses, the cow’s requirement for P drops. The important thing is to work with your vet, adviser or nutritionist, to make sure the right supplementation model works for your farm.
We saw good results with higher P in meal and also with supplementation through water for 3-4 weeks.
Long-term control and solutions
How do I know it’s working?When you correct P levels, depending on the severity of deficiency, the clinical signs usually resolve in around 2-3 weeks.
What if I do nothing?Doing nothing means your herd is low in P, which can affect growth, milk yield and conception. My advice is to take action.
Should I chance some P and see what happens?Like all mineral supplementation, it’s good to get advice around route, timing and amounts to ensure deficits are being corrected.
Having a long term plan.Look at P levels in soil and/or herbage. Soil pH and P and K levels need to be adjusted over time, depending on results and advice from your on-farm adviser. If P level correction is slow, plan P supplementation at risk times, until pasture levels have been corrected.
If it quacks and looks like a duck.We can’t just presume cows eating stones have low P issues, we must look at energy, protein, and other metabolic issues that might contribute. Another thing to be mindful of that affects P levels is heavy parasite burdens, particularly in young stock.
Like everything, treat the problem in the short-term but work hard on long-term control and solutions. Remember, this isn’t a common problem and farms with these symptoms should be aware of what to do.
Over the last four-to-five years around this time of year, I’ve seen an increase in cases of cows eating stones. This condition called pica is not just cows eating stones, but plastic, timber, feasting in ditches and chewing on the bark of trees. So why have we seen an increase and is this perceived increase real?
My own opinion is that it definitely is an emerging problem on some dairy farms. Interestingly, last summer I saw very few cases during the warm, dry summer months. In the last week, I spoke with two farmers who had what could be considered suspect cases. I also spoke to a farmer in early February who had yearling heifers eating gravel and stones.
Causes
You can always have an occasional cow or a couple of cows doing this, but what I’m seeing is a significant percentage of herds affected, with some of the herds I’ve seen having over 10% of cows affected. There are a number of theories around why this pica or depraved appetite may occur. I’ve settled on two main ones because of the time of year we generally see it.
Phosphorus is a key element in plant growth and also in the cow’s physiology
The first cause of pica I have diagnosed in several herds is due to a phosphorous (P) deficiency. Phosphorus is a key element in plant growth and also in the cow’s physiology. It is critical in bone growth, enzymes, energy conversion and protein digestion in the rumen.
The second cause I have encountered is due to low energy to protein ratio in early spring. This can usually be compounded by spring grass low in fibre. This fast-growing, leafy spring grass can affect the rumen function in cows in some cases. The lack of fibre can particularly affect rumen function. This type of sub-acute ruminal acidosis (SARA)can affect cows’ grazing habits, leading them to seek out more unpleasant things to consume.From what I have seen personally, adding some fibre into the diet of these herds leads to a big improvement.
Low sodium has also been theorised as a cause but I’ve yet to see this in grazing cows, more commonly encountering it indoors. A very easy way to rule this out is to add cheap salt blocks in buckets at grass.
If cows are deficient they will consume the salt and stop this behaviour. Salt is the only mineral that cows self-regulate, meaning they will only seek it out when they are deficient and need to.
What you can do
I think supplementing blind is not ideal. Why? Because of the complex mineral interactions and the chance of something else being wrong. Your vet, nutritionist or adviser will be able to look from the outside-in.
Rumen health and energy or protein issues can be observed by looking at protein to butterfat ratios, as well as yields and cow performance
The best way to diagnose a phosphorous deficiency is through careful on-farm history and blood testing a cohort of affected animals. Your vet can do this blood test on between 8-10 animals looking at blood levels.
The herd history is very important also, looking at P indexes on-farm. Low P indexes, with the history of pica, always make me suspicious of phosphorous problems.
Rumen health and energy or protein issues can be observed by looking at protein to butterfat ratios, as well as yields and cow performance. I think examining the faeces of cows is useful, while we would expect them to be loose, we don’t want green watery scours. This problem will often resolve itself over time or else with the supplementation of fibre in the diet. This is a very brief overview and obviously requires more in-depth analysis to find farm-specific solutions. Remember, there are other reasons for cows to be scouring and they should always be investigated.
Phosphorous supplementation
On many of the farms we investigated through blood sampling, we found low phosphorus percentages in the animals examined. Carefully choosing the cows to sample was critical, taking down tag numbers of cows chewing stones or showing signs of pica greatly helped identify the problem.
Short-term plans involved supplementing phosphorous through meal, water or other sources
Next, we made a diagnosis and drew up short-term plans and more importantly long-term farm specific plans.
Short-term plans involved supplementing phosphorous through meal, water or other sources. If feeding concentrates, then a lot of mills can add P to concentrates, looking at daily requirements of 0.4% of DM intake, or a cow’s daily requirement of around 70g of P a day. If going by water, I have found that working out requirements and supplementing up to 3-4 weeks during risk periods made a difference.
My own personal experience is that supplementation for less than two weeks does not significantly affect clinical signs. Of course, this can be farm-specific depending on the severity of the problem, source of P and blood results.
As lactation progresses, the cow’s requirement for P drops. The important thing is to work with your vet, adviser or nutritionist, to make sure the right supplementation model works for your farm.
We saw good results with higher P in meal and also with supplementation through water for 3-4 weeks.
Long-term control and solutions
How do I know it’s working?When you correct P levels, depending on the severity of deficiency, the clinical signs usually resolve in around 2-3 weeks.
What if I do nothing?Doing nothing means your herd is low in P, which can affect growth, milk yield and conception. My advice is to take action.
Should I chance some P and see what happens?Like all mineral supplementation, it’s good to get advice around route, timing and amounts to ensure deficits are being corrected.
Having a long term plan.Look at P levels in soil and/or herbage. Soil pH and P and K levels need to be adjusted over time, depending on results and advice from your on-farm adviser. If P level correction is slow, plan P supplementation at risk times, until pasture levels have been corrected.
If it quacks and looks like a duck.We can’t just presume cows eating stones have low P issues, we must look at energy, protein, and other metabolic issues that might contribute. Another thing to be mindful of that affects P levels is heavy parasite burdens, particularly in young stock.
Like everything, treat the problem in the short-term but work hard on long-term control and solutions. Remember, this isn’t a common problem and farms with these symptoms should be aware of what to do.
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