Lungworm *HIGH RISK*
Extended grazing into a late mild Autumn means very short lungworm life cycles and rapid build up of larvae on the pasture despite good control all summer.
Ivermectin pour-on stops re-infection with Lungworm for 28 days, Moxidectin pour-on stops re-infection for 6 weeks , and the long acting injectable (behind the ear) Moxidectin stops re-infection for 120 days so regardless of worming strategy - ALL younger animals could be considered vulnerable at this time of year as we make the most of the extended grazing period without a frost.
The first sign you'll see is coughing when you move the group. Don't delay on treatment.
Crypto control in calves - a review
We often think of Crypto as being a seasonal disease that builds up in calving yards as cows calve inside through the back end of the year. A tipping point in infection pressure is reached, usually around Christmas, and you can see spikes of disease in calf pens from January onwards. Making sure calving yards and calf pens are cleaned out and disinfected is essential to reduce build up of Crypto eggs over time.
What is Crypto?
Crypto is a gut parasite: not a bacteria or a virus but a protozoan like cocci, and is one of the most common causes of scour on farm. Crypto can cause significant scour by itself, but when you get mixed infections with Rotavirus or Coronavirus the scour is severe and you can get significant calf losses. There are four species of Crypto that are found in the guts of cattle, but only one of them (Cryptosporidium parvum) causes disease in calves.
Don't forget Crypto can affect humans too - so please make sure everyone dealing with calves wear gloves and you have strict hand washing policies on farm
The Lifecycle:
The infective stage of the lifecycle are the "oocysts" which are the Crypto eggs that are shed into the scour. Each oocyst contains four "sporozoites" which are released when the egg is ingested - and it is these that attach and invade the gut cells. Inside the gut cells the sporozoites go through a number of cycles of reproduction over 2-7 days and produce more oocysts - the process of this damages the cell which then explodes releasing all the oocysts into the gut. It is this gut cell damage that causes gut pain, poor appetite, poor absorption, scour and sick calves.
Did you know?
Two types of oocyst are released from the gut cells - a thick walled one that is shed in the scour and can survive for 12 months in the environment, and a thin walled one which immediately bursts and releases the four infective sporozoites whilst still within the calves gut causing immediate re-infection and worsening symptoms.
Calves can be infected at a few hours old by suckling a contaminated teat, or nosing around trying to find the teat, or from a contaminated feeding equipment; stomach tubes and teats must be washed and disinfected between calves.
The infectious dose for Crypto is only 10 oocysts. It usually takes a few days for the scour to start and by day 5-7 they can be shedding 10 million oocysts in every gram of their muck and so infection rapidly builds up and then very easily spreads calf to calf in the calf shed.
What do you see?
- scour from 5-14 days old
- weak, dull, depressed calves
- poor appetite - won't finish a feed
- loose, yellow, watery scour (can sometimes see blood or mucus)
- +/- straining
- in severe cases, calves can't stand and become so dehydrated they may die
Diagnosis:
We have calf-side scour test kits that can give us a diagnosis within 5 minutes showing what bugs are causing your calf scour so treatment and prevention strategies can be targeted.
Treatment options:
There is no vaccine for Crypto and no single effective cure; the basis for recovery is aggressive fluid therapy to replace the scour losses, careful use of anti-inflammatories so they are comfortable enough to keep drinking, time to let the gut recover. and TLC (a heat lamp can be really helpful).
If the calf is severely affected, or there is blood in the scour we will sometimes add in antibiotics, not because the antibiotics will sort the Crypto, but because a dehydrated, inappetent calf is massively at risk of secondary bacterial invaders and septicaemia.
Halofuginone
Halofuginone ("Halocur" or "Halogan") is both a treatment for crypto and a prevention strategy - it is an oral liquid that has to be administered once a day for 7 days - either at 24 hours old as a prevention or within 24 hours of the scour starting. The exact way Halofuginone works is unknown but it seems to reduce the sporozoites in the gut and reduce the number of oocysts in the scour. This doesn't stop the scour but can reduce the environmental contamination.
There are significant risks when it comes to using Halofuginone:
- It is toxic at just twice the recommended dose rate so you have to have accurate weights so you can accurately dose
- It must only be used after a milk feed, and not on an empty stomach
- The calf must be well and hydrated before use - if it is used in a dehydrated, sick animal it can make the situation worse
- It requires someone to handle each calf and their mouths, every day from 24 hours old for a whole week - this in itself is a risk and can inadvertently spread Crypto oocysts from pen to pen, or calf to calf so hygiene of the person treating calves, and the bottle/equipment that is used is crucial
Prevention:
The mainstay of prevention comes down to hygiene in the environment and reducing oocyst contamination of the environment.
- Calving yard
Muck out, steam clean, allow to dry and disinfected with an approved Crypto disinfectant every few weeks. Use sand on the base of the yard if you're worried about grip for calving cows.
- Calf pens
Muck out between each calf or group, steam clean, allow to dry and disinfect with an approved Crypto disinfectant. Crypto loves the damp so poorly drained pens, or poor drainage around auto-calf feeders or water feeders or squelchy bedding carries huge risk.
- Bedding
Calves will pick at a straw bed from a very young age so a deep, clean, dry straw bed is vital to reduce the exposure between calves and oocysts. There are some studies to show using lime as a base in calf areas can help reduce oocyst survival too.
- Feeding Equipment
Make sure all feeding equipment is clean before going in the calf pens and always feed youngest to oldest and then any poorly ones. Crypto loves a biofilm so make sure you rinse feeders in lukewarm water before your hot wash routine.
- People
Make sure anyone going into the calf pens are visibly clean, wear gloves and there is a fresh boot dip on entry that is used.
- Immunity
We can't mention calf scour without mentioning colostrum! It is vital that calves get great colostrum uptake 365 days a year. There are a lot of different management pressures on you, the cow and the calf at calving; you might be snatching calves for Johne's prevention, having spikes in numbers of cows calving, getting maize in - but those first few feeds are the most important feeds that calf will get.
Crypto Disinfectants:
The disinfectant has to break down the wall of the oocyst and only a few disinfectants will do that. 3% Cyclex kills 99% of oocysts after 4 hours of contact time.
Remember: disinfectants ONLY work on a clean surface. Crypto oocysts survive from temperatures as low as -20°C and up to 60°C so the sheds, pens or hutches need to be mucked out, steam cleaned at >60°C then left to dry. The disinfectant then needs to be applied at the right concentration, at the right rate and is left for the correct contact time.
Cyclex Use:
DILUTION: 3% solution
DOSE RATE: 0.3 litres per square metre
CONTACT TIME: 4 hours
Crypto top tips:
Make sure there's always a clean, dry bed
Get colostrum right for every calf
Make sure it is Crypto
Get a good treatment plan in place
Clean and disinfect pens frequently
Johnes NJMP declaration deadline - due December 31st 2021
Over the next few months we will be reviewing your Johne's control plans on farm so you can get the declaration off to your milk buyer before the deadline of 31st December 2021.
Remember if you have ever had a positive test result in the herd then the minimum testing is a single test before dry off for every breeding animal. This allows decisions to be made about where she calves, if her colostrum can be used and future breeding options for next lactation.
The more times you test, the more reliable a repeated negative result becomes so adding in a second pre-breeding test alongside the dry off test can be very useful to help make accurate breeding decisions for her next pregnancy.
For those of you testing 4 times a year we can start to monitor patterns of new infections, check rates of new milking heifer infections, understand your cull risk and pinpoint particular patterns of disease on your farm using "Herd Tracker".
GET IN TOUCH:
Paula: 07764 747855 paula@haywoodfarmvets.com
Tom: 07837 291097 tom@haywoodfarmvets.com
Enquiries: mail@haywoodfarmvets.com
Website: haywoodfarmvets.com
Open hours: M-F 08:30 - 16:30
Out of Hours: 07398 743095