Gut worm and lungworm control in dairy youngstock
- What worms can be a problem for dairy youngstock?
- How to diagnose worms in dairy heifers
- Worming dairy heifers
- Is wormer resistance a problem in cattle?
Good parasite management is vital for the health of the dairy herd, especially the management of gut worms and lungwormin dairy heifers. Heifers with mild worm burdens have reduced grazing times, reduced DMI and an average of 0.15kg/day reduction in liveweight gain.1 Scouring animals are even more severely affected.1 With average heifer growth targets of 0.7-0.8kg/day, affected heifers can be significantly behind by the time they reach 13 – 15 months – the ideal service period. This can lead to a delay in first service or poorly grown pregnant heifers which are more likely to have problems calving and integrating into the herd.
Youngstock that have not been exposed to worms before (first grazing season or that have been over-wormed while at pasture) are considered the highest risk for developing clinical disease suchas ‘husk’ due to lungworm infection, or parasitic gastro-enteritis (PGE) due togut worms. Their immune systems have not had any exposure to worms, so theanimals have not had a chance to develop immunity. Heifers in their first (and sometimes second) grazing season are likely to need a worm management programmeto help keep worm burdens down to a low level (which will stimulate immunitybut not cause disease).
Healthy cattle which are gradually exposed to worm larvae (gut and lungworm) at pasture will develop long-lasting immunity which is ‘boosted’ every time they are exposed to worms again. By the time they are adult dairy cows the high levels of immunity mean they may not need treatment for gut worms. The exception for lungworm is when naïve dairy cows(which have never encountered lungworm before) are brought into a herd where lungworm is present. Clinical ‘husk’ may be seen in these animals in their first grazing season on lungworm-infected pasture.
What worms can be a problem for dairy youngstock?
There are several ways in which roundworms can affect dairy heifers:
1) Parasitic gastro-enteritis (PGE)– this can be due to Ostertagia ostertagi (stomach worm) or Cooperiaoncophora (intestinal worm). These worm species can act individually or together to reduce appetite and feed intake, damaging the gut to prevent cattle from efficiently extracting nutrients from their feed. Cattle ingest worm larvae which develop into adult worms over approximately 3 weeks. These then shed eggs into the faeces, which further contaminates the pasture. Inpermanently grazed pasture, the worm burden will gradually increase over thegrazing season. This can be worsened if there is sudden wet weather after a hotdry spell, as this causes many eggs to hatch at once leading to severe damage and diarrhoea (so called Type 1 Ostertagia).
2) Type 2 Ostertagia – Ostertagialarvae ingested by youngstock in late autumn and winter undergo hypobiosis– a hibernation of larvae within the lining of the fourth stomach. In spring, large numbers of larvae hatch out at once causing severe damage to the stomach lining and sudden onset severe diarrhoea which can be fatal. This can be seen in housed youngstock if they were not treated appropriately after housing.
3) Lungworm (Dictyocaulusviviparus) – this worm migrates from the gut to lung and can cause severelung damage which can be fatal. It is mostly seen in summer and early autumn and presents as groups of cattle coughing at grass.
How to diagnose worms in dairy heifers
There are several tools which we use todiagnose gut worms in dairy heifers:
- Growth rates – if done frequently and recorded, this can be a good indication of animal health. However, it doesn’t tell us if worms are the problem or if there are other health or nutritional issues.
- Faecal worm egg counts (FWECs)*- can be useful for diagnosing PGE, as worm burdens usually increase gradually along with worm eggs produced in the faeces. FWECs are easy to do -collect thesame amount (a teaspoon) of fresh faeces from at least 10 animals in the group.The sample should be tested as soon as possible after collection. The FWEC canbe done on farm if you have the kit, by your vet, or some agriculturalmerchants will offer the service. A FWEC will give an approximate measure ofthe severity of the worm burden present. A discussion should be had with yourvet/SQP/RAMA to discuss results.
Regular FWECs of a group over the summer can help identify when the worm burden is increasing and which pastures have the highest worm burden. FWECs should be used in conjunction withgrowth rates, clinical signs, and parasite forecasts.
*There are times when FWECs may not be appropriate e.g. in cases where the worm burden increases very quickly and the damage is caused by larvae rather than adults. The FWEC may below, but significant disease present. FWECs rely on there being adult worms present in the gut producing eggs to detect.
- Clinical signs – these are notusually seen until significant gut damage has been done, so relying on clinicalsigns alone can still allow significant growth rate reductions. You should aimto treat animals before they start showing clinical signs of worms.
Diagnosis of lungworm is mainly by the observation and clinical examination of groups of grazing animals coughing onpasture which is known to have lungworm present. Sending muck samples to the lab for lungworm larvae detection can help confirm the diagnosis.
Worming dairy heifers
We are more limited in treatment optionsfor cattle compared to sheep. There are only three classes of wormer licensed for cattle, compared to five for sheep. These are available as either an oral drench, injection or pour-on. Some wormers are also available as combination products, treating external parasites (mites, lice) and fluke. The wide rangeof wormer brands can be daunting when selecting a product. However, these are thethree wormer classes you could use in cattle:
1. Group 1 BZ – White wormer (Benzimidazoles) – confusingly, these can also be green, cream, or blue in colour –for example Albex, Bovex, Zerofen.
2. Group 2 LV – Yellow wormer(Levamisole) – for example Chanaverm
3. Group 3 ML* – Clear(Ivermectin, Eprinomectin etc) – for example Animec pour-on, Animec injection and Epromec pour-on.
It can take two grazing seasons to establish effective immunity against gut worms in dairy heifers as it takes roughly 8 months of grazing pasture with worms present to build up the required immunity.2
This presents a challenge when selecting treatment options for second season grazing heifers as these animals are likely to be in calf. Many wormers cannot be used in late pregnancy without affecting the safety of the milk produced in the next lactation. If you are needing to worm pregnant heifers, then there are limited options:
Is wormer resistance a problem in cattle?
While wormer resistance is not as widely publicised in cattle as it is in sheep, it is being more routinely reported in cattle in the UK. Wormer resistance poses a big risk to dairy youngstock health and welfare, especially as the range of wormer classes available are relatively narrow. If the gut worms on your farm develop resistance to Ivermectin, for instance, gut worm control is going to be a real challenge.
The aim of heifer worm management is to allow low levels of exposure to worms to stimulate their immunity for future grazing seasons, while treating them before the worm burden gets to the level of causing significant growth checks or clinical signs.
Pasture and youngstock worm burdens can be affected by many factors including pasture management, stocking rate, weather patterns, temperature, and health of the animals. This makes it very difficult to predict with certainty when animals will need worming without the use of diagnostic tests. The dairy industry is moving away from routine or ‘set’ worming throughout the summer grazing as:
1) The timing may not be optimal and may still lead to growth checks.
2) With this method cattle areoften wormed when it is not necessary, which increases the risk of anthelminticresistance developing in future.
To reduce the chance of resistance developing, treatment should be targeted to animals or groups of animals that need it. This targeted treatment plan should be discussed with your vet or SQP/RAMAto reduce the pasture build-up of worm eggs, allowing your youngstock to develop immunity with no adverse effects on their health. Any treatments should be administered correctly so that the animals receive an effective dose of wormerat the right time. See COWS website for more information on effective worming in cattle.
FWECs can be used to check if the wormer you have used has been effective, by testing the reduction in worm egg count before and after treatment – speak to your animal health advisor about testing the wormer efficacy on your farm.
References:
1. Forbes et al, Evaluation of theeffects of nematode parasitism on grazing behaviour, herbage intake and growthin young grazing cattle
2. roundworm-140120.pdf(cattleparasites.org.uk)
Gut worm and lungworm control in dairy youngstock
- What worms can be a problem fordairy youngstock?
- How to diagnose worms in dairyheifers
- Worming dairy heifers
- Is wormer resistance a problemin cattle?
Good parasite management is vital for the health of the dairy herd, especially the management of gut worms and lungwormin dairy heifers. Heifers with mild worm burdens have reduced grazing times, reduced DMI and an average of 0.15kg/day reduction in liveweight gain.1 Scouring animals are even more severely affected.1 With average heifer growth targets of 0.7-0.8kg/day, affected heifers can be significantly behind by the time they reach 13 – 15 months – the ideal service period. This can lead to a delay in first service or poorly grown pregnant heifers which are more likely to have problems calving and integrating into the herd.
Youngstock that have not been exposed to worms before (first grazing season or that have been over-wormed while at pasture) are considered the highest risk for developing clinical disease suchas ‘husk’ due to lungworm infection, or parasitic gastro-enteritis (PGE) due togut worms. Their immune systems have not had any exposure to worms, so theanimals have not had a chance to develop immunity. Heifers in their first (and sometimes second) grazing season are likely to need a worm management programmeto help keep worm burdens down to a low level (which will stimulate immunitybut not cause disease).
Healthy cattle which are gradually exposed to worm larvae (gut and lungworm) at pasture will develop long-lasting immunity which is ‘boosted’ every time they are exposed to worms again. By the time they are adult dairy cows the high levels of immunity mean they may not need treatment for gut worms. The exception for lungworm is when naïve dairy cows(which have never encountered lungworm before) are brought into a herd where lungworm is present. Clinical ‘husk’ may be seen in these animals in their first grazing season on lungworm-infected pasture.
What worms can be a problem for dairyyoungstock?
There are several ways in which roundworms can affect dairy heifers:
1) Parasitic gastro-enteritis (PGE)– this can be due to Ostertagia ostertagi (stomach worm) or Cooperiaoncophora (intestinal worm). These worm species can act individually or together to reduce appetite and feed intake, damaging the gut to prevent cattle from efficiently extracting nutrients from their feed. Cattle ingest worm larvae which develop into adult worms over approximately 3 weeks. These then shed eggs into the faeces, which further contaminates the pasture. Inpermanently grazed pasture, the worm burden will gradually increase over thegrazing season. This can be worsened if there is sudden wet weather after a hotdry spell, as this causes many eggs to hatch at once leading to severe damage and diarrhoea (so called Type 1 Ostertagia).
2) Type 2 Ostertagia – Ostertagialarvae ingested by youngstock in late autumn and winter undergo hypobiosis– a hibernation of larvae within the lining of the fourth stomach. In spring, large numbers of larvae hatch out at once causing severe damage to the stomach lining and sudden onset severe diarrhoea which can be fatal. This can be seen in housed youngstock if they were not treated appropriately after housing.
3) Lungworm (Dictyocaulusviviparus) – this worm migrates from the gut to lung and can cause severelung damage which can be fatal. It is mostly seen in summer and early autumn and presents as groups of cattle coughing at grass.
How to diagnose worms in dairy heifers
There are several tools which we use todiagnose gut worms in dairy heifers:
- Growth rates – if done frequently and recorded, this can be a good indication of animal health. However, it doesn’t tell us if worms are the problem or if there are other health or nutritional issues.
- Faecal worm egg counts (FWECs)*- can be useful for diagnosing PGE, as worm burdens usually increase gradually along with worm eggs produced in the faeces. FWECs are easy to do -collect thesame amount (a teaspoon) of fresh faeces from at least 10 animals in the group.The sample should be tested as soon as possible after collection. The FWEC canbe done on farm if you have the kit, by your vet, or some agriculturalmerchants will offer the service. A FWEC will give an approximate measure ofthe severity of the worm burden present. A discussion should be had with yourvet/SQP/RAMA to discuss results.
Regular FWECs of a group over the summer can help identify when the worm burden is increasing and which pastures have the highest worm burden. FWECs should be used in conjunction withgrowth rates, clinical signs, and parasite forecasts.
*There are times when FWECs may not be appropriate e.g. in cases where the worm burden increases very quickly and the damage is caused by larvae rather than adults. The FWEC may below, but significant disease present. FWECs rely on there being adult worms present in the gut producing eggs to detect.
- Clinical signs – these are notusually seen until significant gut damage has been done, so relying on clinicalsigns alone can still allow significant growth rate reductions. You should aimto treat animals before they start showing clinical signs of worms.
Diagnosis of lungworm is mainly by the observation and clinical examination of groups of grazing animals coughing onpasture which is known to have lungworm present. Sending muck samples to the lab for lungworm larvae detection can help confirm the diagnosis.
Worming dairy heifers
We are more limited in treatment optionsfor cattle compared to sheep. There are only three classes of wormer licensed for cattle, compared to five for sheep. These are available as either an oral drench, injection or pour-on. Some wormers are also available as combination products, treating external parasites (mites, lice) and fluke. The wide rangeof wormer brands can be daunting when selecting a product. However, these are thethree wormer classes you could use in cattle:
1. Group 1 BZ – White wormer (Benzimidazoles) – confusingly, these can also be green, cream, or blue in colour –for example Albex, Bovex, Zerofen.
2. Group 2 LV – Yellow wormer(Levamisole) – for example Chanaverm
3. Group 3 ML* – Clear(Ivermectin, Eprinomectin etc) – for example Animec[SS4] pour-on, Animec injection and Epromec pour-on.
It can take two grazing seasons to establish effective immunity against gut worms in dairy heifers as it takes roughly 8 months of grazing pasture with worms present to build up the required immunity.2
This presents a challenge when selecting treatment options for second season grazing heifers as these animals are likely to be in calf. Many wormers cannot be used in late pregnancy without affecting the safety of the milk produced in the next lactation. If you are needing to worm pregnant heifers, then there are limited options:
Is wormer resistance a problem incattle?
While wormer resistance is not as widely publicised in cattle as it is in sheep, it is being more routinely reported in cattle in the UK. Wormer resistance poses a big risk to dairy youngstock health and welfare, especially as the range of wormer classes available are relatively narrow. If the gut worms on your farm develop resistance to Ivermectin, for instance, gut worm control is going to be a real challenge.
The aim of heifer worm management is to allow low levels of exposure to worms to stimulate their immunity for future grazing seasons, while treating them before the worm burden gets to the level of causing significant growth checks or clinical signs.
Pasture and youngstock worm burdens can be affected by many factors including pasture management, stocking rate, weatherpatterns, temperature, and health of the animals. This makes it very difficultto predict with certainty when animals will need worming without the use ofdiagnostic tests. The dairy industry is moving away from routine or ‘set’worming throughout the summer grazing as:
1) The timing may not be optimaland may still lead to growth checks.
2) With this method cattle areoften wormed when it is not necessary, which increases the risk of anthelminticresistance developing in future.
To reduce the chance of resistance developing, treatment should be targeted to animals or groups of animals that need it. This targeted treatment plan should be discussed with your vet or SQP/RAMAto reduce the pasture build-up of worm eggs, allowing your youngstock to develop immunity with no adverse effects on their health. Any treatments should be administered correctly so that the animals receive an effective dose of wormerat the right time. See COWS website for more information on effective worming in cattle.
FWECs can be used to check if the wormeryou have used has been effective, by testing the reduction in worm egg count beforeand after treatment – speak to your animal health advisor about testing thewormer efficacy on your farm.
References:
1. Forbes et al, Evaluation of theeffects of nematode parasitism on grazing behaviour, herbage intake and growthin young grazing cattle
2. roundworm-140120.pdf(cattleparasites.org.uk)