Recent years have seen a growing number of dairy farmers in Northern Ireland focus on a more compact autumn/early winter calving season with a significant proportion of their herds.
The theory behind this approach is a simple one. A greater proportion of the milk produced is eligible for the winter milk bonuses on offer from the dairies. And, in addition, cows put safely back in calf can be let out into paddocks the following spring in order to generate significant quantities of milk from grazed grass.
But this still leaves the farmer with the challenge of calving cows down successfully. In other words, allowing them to maximise milk output from the start of their new lactations and subsequently coming back into calf again, when required.
According to United Feeds’ nutritionist, Jenny Hamilton, a key target in this regard is drying cows off with a body condition score in the region of 3.0 and keeping it at this level right through to point of calving.
“Feeding cows well in later lactation is much more efficient than drying cows off thin and building condition when dry.
The weeks leading up to, and following calving constitute the most important period in a cow’s production cycle. This is because fundamentally they determine the outcome of the animal’s next lactation. The priorities are to successfully deliver a healthy calf, ensure that the mother has ample, high-quality colostrum and to have the cow come back into full milk as quickly as possible.
Making this happen requires a commitment to ensure that the dry cow’s management needs are met in full.
United Feeds’ Business Development Advisor & nutritionist, Andrew Fyffe takes up that story.
“Nutrition plays a key role in this context. The cow is a ruminant animal. So, feeding a high dry matter, palatable silage with good levels of energy and protein is important.
“If this approach is taken, it should be physically possible for even close-up dry cows to consume up to 10kg of dry matter per day.
“So, bringing dry cow silages up to a dry matter of 30% to 40% is necessary to make this happen. These forages should also have a relatively high fibre content. ”
“But one trap to be avoided at all costs is that of feeding dry cows forages containing a high level of potassium.”
“High potassium levels in pre-calver diets will predispose cows and heifers to a range of metabolic disorders post calving.
“We strongly recommend that dairy farmers should make bespoke dry cow silages. This will require the farmer not to spread slurry or any chemical fertiliser containing potash on the swards to be ensiled throughout that growing season.
“Slurries contain high levels of potash, so even fields spread early in the season can still produce high potassium forages, depending on the application rate, crop maturity and soil ‘K’ index.”
It’s important to stress that as the main component of any dry cow diet is forage, therefore it has by far the biggest bearing on the success of the transition period. Concentrates are meant to complement the forage and providing what is lacking, primarily starch, protein, vitamins, and minerals.
United Feeds recommend analysing dry cow forage, not just with NIR to provide dry matter, energy and protein but also to conduct a mineral analysis. This will provide an indication of the potassium level but crucially the cation-anion balance. The United Feeds team can then advise how to balance the diet accordingly. The company’s pre-calver range has been designed for a daily rate of 2 – 3kg/head/day.
Jenny Hamilton explains the benefits of their dry cow range:
“In the first instance, the ration acts to prime the pre-calving animal for calcium release, which is controlled by a complex hormone mechanism that mobilises calcium from the bones and gut, requiring magnesium.
To encourage calcium release we formulate our pre-calver to a strict mineral specification where we limit calcium and sodium but increase magnesium and phosphorus.
“This is very different to a milking cow ration.”
She continued:
“The acid-base status of the cow also affects these hormone mechanisms. We include magnesium chloride not only as a magnesium source, but to slightly acidify the blood, thereby increasing calcium availability.
This is known as a partial dietary cation anion balanced, or DCAB diet.
“Problems arise if forages fed are too high in potassium as this reduces magnesium availability.
The United Feeds’ ration helps to mitigate against clinical and sub-clinical milk fever, but the lower the potassium & sodium levels in dry cow forages, the lower the chance of milk fever.
United Feeds’ pre-calver range also primes the rumen. Energy intake in early lactation is crucial to performance for milk and fertility.
Jenny Hamilton again:
“We need to maximise dry matter intake (DMI) and the use of feed in early lactation. The rumen has adapted to digesting a fibre only diet in the far-off dry period, so starch is needed to stimulate starch-digesting microbes and elongate rumen papillae, thereby preparing the cow for digesting a high concentrate lactation diet.
“Well adapted rumen papillae are necessary to prevent ruminal acidosis in early lactation. But this process is gradual. Hence the importance of this process beginning prior to lactation.”
She added:
“Yea-Sacc, a highly effective yeast, is included in our pre-calver ration to promote growth and activity of ruminal bacteria, aiding digestion and stabilising pH to encourage DMI.”
The liver is also central to energy management in the cow. It processes energy from feed and body reserves to support milk production in early lactation.
United’s pre-calver diet also contains the feed additive ‘LiFT’. It provides vitamins and essential cofactors to support healthy liver function, thereby facilitating energy mobilisation, fat export and ketone reduction.
The end result is increased milk yield and quality in tandem with a minimal risk of transition cow diseases.
And, finally Jenny explains that United’s pre-calver concentrate also acts to prime the immune system.
Its vitamin and mineral package is more concentrated than is the case with a milking ration because it is formulated for a 2-3kg feed rate.
She concluded:
“It includes organic selenium, copper, zinc and manganese, along with other essential trace elements, vitamins, antioxidants and biotin.
“These all play crucial roles in aiding calving ease, reducing the likelihood of retained placentas and metritis, reducing somatic cell count in early lactation, supporting hoof health, improving fertility through improved conception rates and reducing days to first service.
“The inclusion of Bio-Mos reinforces the cow’s natural defences, supporting gut health by inhibiting colonisation of pathogenic bacteria in the gut; such as salmonella and E-coli.
“This also enhances colostrum quality, which benefits the new-born calf’s immune system.
Trials have confirmed an increase rotavirus titres and immunoglobulin levels in calves whose dams were fed Bio-Mos pre-calving.”
