Vigilance urged for pre-calving health before onset of spring
Published 23/01/2013 | 06:00
With the calving season nearly upon us, there are numerous aspects of animal health that need to be considered before we get thrown into the heat of the action.
In this article, I will address the health risks and preventative strategies for three categories of cows: the dry cow; freshly calved cows and heifers; and finally maiden heifers.
First off, let's start with managing the body condition score of the dry cow.
Managing dry cow nutrition this winter has been a challenge. Stories of silage being in short supply and of poor quality, has been the norm, not the minority. Even for those farmers who out-winter on crops, delayed sowing compromised yields and grazing conditions.
Most dairy farmers have managed their individual situation by determining how much winter feed they had and balanced the deficit with either additional concentrate, forage or other feeds such beet.
Having observed dry cows recently on a number of farms, there are certainly cows that are 'fit'.
There are fewer cows that are 'fat' but there are also a few cows which could be classed as 'thin'.
The reality this spring is that cows will generally be calving at the target body condition score (BCS) of just above BCS 3 but there will be more cows calving at less than BCS 3 compared to last spring.
So what are the potential health impacts this spring?
Dairy farmers hate difficult calvings and rightly so. These tend to be associated with over-fat cows, and large calves.
As the latter is more of a concern than the risk of fat cows this year, farmers may now begin to become concerned about the amount of concentrate that they are feeding to dry cows that are less than a month from calving.
High concentrate feeding creates a risk of producing large calves and as a result, farmers may be tempted to remove the concentrate from the diet.
However, we must remember that a dry cow has an increasing demand for nutrients in late pregnancy, and intake is reduced so changes to the diet should be made with due consideration.
For a start, many dairy farmers are getting alarmingly close to the back wall of their silage pits or nearing the last of their stocks, so the reality is that there is no extra silage to replace any concentrate that is removed.
Secondly, silage quality is poor which means there is a greater risk of cows receiving inadequate nutrients. Thin cows and poor nutrition are more likely to result in weak calves, lower quality colostrum, lower milk yield and create some compromise on reproduction.
Therefore it's still important to adequately feed the dry cow. Aim to provide adequate feeding space, avoid overcrowding and group cows according to calving date, condition and age.
Disease and parasite control
Each farm needs to manage its own disease risks and consider its bio-security, vaccination and dosing regimes.
Depending on the disease risks associated with the farm, vaccination of IBR, salmonella, rotavirus and coronavirus should be given one month prior to calving where necessary and final doses for parasites should be considered.
This is especially true for rumen and liver fluke following such a wet summer, where the doses used only kill the adult flukes. Note that vaccination for BVD and leptospirosis should generally be implemented one month prior to mating.
Magnesium is essential to prevent milk fever and grass staggers. Provide adequate magnesium supplementation to dry cows. Dry cows need around 0.35pc of their daily dry matter diet as magnesium.
A general rule of thumb is to supplement 10-15g Mg/cow/day from three to four weeks before calving until 12-14 weeks after calving. Deficiencies in trace elements such as iodine and selenium may also result in protracted calvings, weak calves and poor immune defences.
Forage analysis and blood samples may help determine whether your present mineral supplementation is adequate prior to calving.
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