Focus for 100: Grazing, minerals and getting the balance right
With up to 80% of all metabolic problems a dairy cow can experience occuring in the transition period, now is a crucial time to get the balance right on for cow nutrition, writes Alltech Ireland's Eddie Phelan.
Following on from such extreme weather events in January, farmers are feeling great relief with the more settled weather of late.
The memories of last summer’s slow growth rates, coupled with winter forage shortages, are fading as the grazing season gets going.Â
Total farm covers are good but wide-ranging, anywhere from 700–1,300kg of dry matter per hectare. 10-40% more grass is available compared to other years, and we can capitalise on this.
A lot of farmers have easy calvings with minimal intervention or metabolic issues. This gives the dairy cow a fantastic start to her lactation and breeding season. Of course, other cows and farms will struggle. A dairy cow goes through two major stress points in her lifetime: weaning and calving. We must make life for our cows as stress-free as possible.
Dry matter intake (DMI) is vital in early lactation. While a cow will not reach peak DMI until 8–10 weeks post-calving, she reaches peak milk yield around six to eight weeks post-calving.
Cows will lose body condition in early lactation because of this, but it should be minimised to less than 0.5 of a body condition unit (4% of body weight). This can be done by pushing DMI and feeding the correct diet in the correct proportions (grass, silage, concentrate) based on your cow and milk yield.
Whether the diet is adequately fuelling the cow will become clear in the weeks after this, where the loss of condition will really become apparent, and production can suffer.
To avoid this, we must make sure the cow is getting the best nutrition from her feed. Several factors play a role in feed efficiency, but rumen health is one of the most important.
Research carried out at University College Dublin (UCD) on the Alltech yeast technology Yea-Sacc® has shown benefits in supporting healthy body condition and subsequent fertility. It does so by promoting a healthier rumen pH and a more stable rumen environment overall, maximising feed efficiency and grass utilisation.Â
The study found a significant increase in available energy coming from the rumen in cows fed Yea-Sacc. The trial, which was carried out in a grass-based farm setting, also demonstrated that the cows mobilised less body fat reserves, retaining better body condition.
The focus of all grazing plans should be on achieving and maintaining high-quality grass all year round.Â
This is done simply by meeting the targeted pre and post-grazing covers of grass, which will vary from farm to farm depending on stocking rate, growth rates and season. The initial target of aiming for 30% of the farm grazed by the end of February is underway on many farms at various levels, again depending on the number of cows calved, land type, weather, etc.
We also must not lose sight of the fact that we are feeding cows, who have just calved, and they are trying to double their intake over the next few weeks. We need to support this where we can and maximise it with the available grass, silage and concentrate.Â
Cows will need to work hard over the next few weeks and should constantly be either eating, cud-chewing or milking. We need to maximise the amount of grazed grass she can eat, avoiding trying to force cows below 4cm, but also not be afraid to supplement the cow when she needs this.
In the absence of this body condition, milk solids and fertility will suffer, with milk yield being the last to drop.Â
The key with supplementary feeding (buffer feeding) is to always be measuring and monitoring. If you know how much grass you have, it is easy to allocate the remaining supplementary feeding necessary. We want to allocate the correct levels and not substitute.Â
For instance, if we offer 12kg of grass DM and 12kg of supplement DM and the cows can only eat 20kg, then this is an issue. While some farms can give many reasons not to budget grass, we need at minimum to be able to measure it and this can be as simple as scoring a cover based on vision.Â
Paddock/field size should also be a focus as cow numbers/stocking rate has increased over the years since quota abolition. Having an area size large enough to fully feed the cows over a 12, 24 or 36-hour period is important, especially in a large herd, as this can manifest itself as underfeeding which might not be fully noticed but still restricting cows by 1-2kg of DM.
The supplement will come in a few different forms, either through a mixer wagon, silage on its own or via the parlour. Your amounts and when to feed these will be determined by your stocking rate, yield/cow type and weather to name but a few.
We always try to eliminate silage as early as possible in the diet as it is a poorer feed compared to grazed grass but if the cow is lacking intake, then always remember that a kilo of something is better than a kilo of nothing.
The cow and, more importantly, the cow's rumen will go through a lot of change over the early lactation period. Doubling its intake over a few weeks, dealing with acidic silage at 12% crude protein, to lush grass of 20-30% protein varying in dry matter by 10% daily, to changing concentrate levels to having to deal with the ever-changing weather. This can impact cows through reducing milk and solids yield and sometimes even sickness.Â
While cows can deal with a lot of it, it is important to support her and her rumen in all of this. Live yeast is a well-known way to stabilise the rumen to help with the peaks and troughs and be able to take the punches when they arrive better. During this time, it should be customary practice when purchasing feed from feed companies or coops to include a live yeast.
It is a busy time of year and it can be hard to keep on top of the many changing events, so it is important to speak to a nutritionist if you feel you have experienced these very solvable issues now or in the past.
As the early-lactation cow increases her DMI from grass and receives less from supplementary feeding, we must ensure that the correct levels of minerals and cal-mag are still in the diet. Ideally, the feeding rate of the parlour concentrates should have the correct pro-rata levels of mineral. As the level of concentrates decreases in the parlour, it is worthwhile to manually weigh what is in a “pull,” to ensure correct calibration.
The integral role that minerals play in the resumption of cyclicity, and the successful breeding of the mid-lactation cow cannot be overlooked. Going into breeding, we want a cow that has a healthy immune system and displays a strong heat.Â
Deficiencies in certain trace minerals can be related to infertility. For example, anoestrous behaviour and silent heats in the herd are linked to deficiencies in copper and manganese. Optimal levels of organic selenium have reduced incidences of metritis and reduced services per conception significantly (Agovino, 2011).Â
A proportion of the mineral should be supplied in an organic form, such as that found in Bioplex® and Sel-Plex®. The mineral is then more bioavailable for absorption by the cow, and there are fewer interactions with antagonists.
As the cow settles into lactation, her appetite has fully recovered post-calving, and she is on course to hit peak milk yield. To maintain a steady lactation and a successful breeding, it is vital that there are no restrictions in DMI.
At regular intervals, it is key to review changes in milk protein, milk yield and BCS, and consider whether there is an energy deficit or a requirement for supplementation at grass.
