WHY DOES MILK FEVER OFTEN COME WITH E.COLI MASTITIS?
Milk fever risk peaks in the first 24 hours after calving - and although some cases may be uncomplicated, simple to treat and quick to respond - others are not.
The primary problem of low calcium (+/- low phosphorous) in milk fever cases can soon develop into secondary complications due to nerve or muscle damage, and if she is slow to respond and get up, pneumonia or mastitis can develop on top.
As you know, calcium is responsible for muscle strength which is why milk fever cases often present as wobbly or down cows. But the big muscles of the skeleton are not the only muscles affected by low calcium.
- The uterus is an enormous muscle by the end of pregnancy, so low blood calcium can cause slow calvings that don't progress or increased numbers of held cleansings/dirty cows as the uterus fails to contract after calving. In severe milk fever cases the whole uterus can prolapse after calving which is one of the true emergencies in farm vetting!
- The rumen is a hugely muscular stomach and cannot contract properly with low calcium levels - notice you'll hear her start to burp again once you start running the calcium in.
- Often a milk fever cow will have a dry nose - the smooth muscle responsible for causing the sweat beading on her nose won't contract - again, a useful marker if you need to repeat the calcium treatment - or is there something else stopping her from getting up?
- The teat end sphincter is also a smooth muscle that seals off the teat from the environment - a vital part of her innate protection against incoming mastitis pathogens.
- White blood cells (the immune cells) also depend on calcium to work effectively; one of the white blood cells called neutrophils are particularly susceptible.
Neutrophils are an important first line of defence against mastitis pathogens; they are made in the bone marrow and when pathogens invade and release toxins the neutrophils are activated and released into the blood. Neutrophils travel in the blood stream and squeeze out of the cells lining the blood vessel to get into the udder - once in the udder they trap and kill the bacteria using toxic granules carried within the cell.
Milk fever cases not only have poorer functioning neutrophils, but calcium is needed to keep the muscle of the teat sphincter shut - so it's a double whammy - you have a cow with open teat ends, with lowered immune function that can't get up so her teat ends are open to the conditions under where she is lying.
We've had some severe E.coli cases in freshly calved cows just lately - heat stress has also been adding to the challenge. Mastitis is very easy to miss in a milk fever case so make sure you strip all four teats once you've put the calcium in.
Always happy to discuss down cow cases with you - we're only at the end of the phone!
NEW: Johne's Disease Progress Tracker
For those of you who are signed up to quarterly individual milk sampling for Johne's disease, there's a new Johne’s progress tracker tool that has been developed by the Johne's Action Group that is available through NMR, CIS or for Interherd+ users.
The Johne’s Progress Tracker compares an individual farm’s data with benchmarks that have a proven, significant impact on infection rates. This means not only can we look at individual cows and track their risk over time, but we can also look at group and herd level markers and identify management decisions that could be holding back your Johne's control.
The tracker measures four key drivers of the disease at a herd level:
PROGRESSION: how many new positives are you getting each quarter? How many of those are milking heifers?
PERSISTENCE: how long are you keeping positives in the herd? Positives don't only pose a risk at calving - they contaminate the environment and make it much harder to rear clean heifers
DISEASE PRESSURE: what breeding decisions are you taking once you know a cow is positive? Is she served again? Does she get to calve again?
REMOVALS: what's the cull risk on your farm for a known positive versus a negative cow?
As always, Johne's disease control is ALL about blocking transmission to the next generation of heifer calves - creating a low risk, cow muck free environment for your replacements is vital.
Look out for your Progress Tracker next time we discuss your Johne's report.
Heat Stress - should you keep on serving?
The last few weeks of July was scorching - most of you will have seen a drop off in milk volume as heat stress kicks in, but how will those hot weeks affect fertility now and in the coming few months?
Heat stress affects fertility in a variety of ways:
Reduced bulling behaviour: during periods of heat stress, cows are less likely to show obvious heats due to reduced hormone levels - this means heats are shorter and less intense so submission rates fall, and the number of negative PD at fertility visits may rise over the next few scanning visits.
Developing follicles: the decrease in hormone levels also affects the normal development of eggs - this mean there are longer follicular waves and follicles are underdeveloped if/when they do ovulate. These poorer quality eggs have a reduced chance of conception compared with normal. Don't forget it takes around 60 days for follicles to develop in the ovary from start to finish so poorer quality follicles may be filtering through over the next couple of months.
Developing sperm: heat stress affects sperm development just the same as follicles - and supresses libido in bulls too; this double whammy effect has big implications for natural service herds.
Embryos: early embryos in the first few weeks after fertilisation are very susceptible to changes in the cows core body temperature as they don't have any heat shock proteins to protect them; in times of heat stress the cows core temperature can rise and kill off developing embryo's. Heat stress also slows the growth of the young embryo which reduces it's hormone signalling to the cow that she is pregnant and so she comes bulling instead of maintaining that pregnancy.
So, should you keep serving in a heat wave?
Yes! Stopping serving is a guarantee there are no pregnancies and that's very rarely cost effective in an all year round calving herd, but it is important for the whole team to know to expect more subtle heats and expect a few more returns after service over the next few weeks. Increasing use of synch protocols and timed AI can be helpful to guarantee ovulation and reduce the need for heat detection when cows are not showing heats as normal.
FLY CONTROL
We're heading into peak fly season, and as you will all know - flies can be both costly and a nuisance to the UK’s cattle and sheep population. In addition to the irritation caused, flies can also transmit a number of diseases, causing both financial and welfare concerns.
Pupae can over-winter in the soil and re-emerge as soon as temperatures rise above seven degrees. Once conditions become favourable, female flies are prolific breeders capable of laying 3,000 eggs over a three-week period. If flies are not controlled on the farm, they can produce 15 generations in one season. Adult flies that you see on and around animals only represent 15 per cent of the total population present the farm, so it is important to act early to reduce the chance of the fly population booming.
As well as the direct irritation and stress caused by painful bites there are significant productivity losses associated with flies and external parasites on cattle, such as; reduced calf weight gain and a reduction in milk yields of up to 20 per cent (Taylor et al. 2012).
The horn fly, Haematobia irritans, can feed on the blood of an animal up to 40 times a day (Bramley et al. 1985). This can lead to anaemia in calves, as well as constant irritation. It can take as few as 10 to 20 head flies, Hydrotaea irritans, per animal to have a negative economic impact on a farm (Wall and Shearer 2001) so make sure you include your calves in your fly treatment protocols.
Biting flies, such as the sheep head fly, are thought to be responsible for the transmission of summer mastitis in cattle. Summer mastitis can cause severe mastitis in the affected quarter, with knock on abortions in severe cases or you may see an increase in heifers calving in with blind quarters from mild, missed cases.
Face flies and the stable fly act as mechanical vectors transmitting the bacteria which cause Infectious Bovine Keratoconjunctivitis or ‘Pink Eye’. This can cause severe ocular damage, as well as a knock-on, long-term effect on their productivity; affected calves can suffer a decrease of 17 to 18 kilograms live-weight at 205 days, when compared with healthy calves (Troutt and Schurig 1985).
Blowfly strike is the most common ectoparasitic infestation affecting sheep in the UK: every year up to 80% of farms will report one or more cases of strike, and this equates to at least 500,000 animals affected in the national UK flock.
Damage caused by strike affects wool clip, hide quality and daily liveweight gains, and can rapidly progress to fatalities within 36 hours. AHDB Beef & Lamb estimates a cost to the English sheep industry of £2.2 million annually.
A combination of cleanliness alongside chemical, biological and physical control methods are often needed to minimise the effect of flies on farm.
Make sure all grazed pregnant cattle are checked at least once a day and all staff are on high alert for the early signs of summer mastitis as we head into August.
GET IN TOUCH:
Paula: 07764 747855 paula@haywoodfarmvets.com
Tom: 07837 291097 tom@haywoodfarmvets.com
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