When we think of winter nutrition, we can sometimes place too much emphasis on what the concentrate proportion of the diet is going to bring to the party, when in most cases, over three-quarters of the diet (in dry matter terms at least) is already sitting in the yard.
What spec of ration should I feed? What protein percentage does it need to be? Where is the energy coming from? Am I overpaying for ration?
Yes, this proportion is important and pound for pound punches above its weight in terms of performance.
However, by putting a bit more thought into the management and delivery of the basal diet – ie grass silage – there is potentially a lot of performance to be harnessed over the course of an entire winter period.
Remember, every unit loss in feed value of silage on-farm will result in either a loss in animal performance or you will have to purchase that performance back in the form of concentrate.
Knowing the value of the silage you are feeding can save a lot, in terms of either the amount of concentrate feed needed or in the expected animal performance attained from forage over winter.
A badly taken silage sample is worse than no silage sample at all, as it can lead to a false sense of security. Sampling silage needs to be given a bit of time and effort to get it right. Too often, samples are taken from one point of the pit or the first bale in the yard to be opened.
If you think about it, there could be hundreds of tons of silage sitting in the yard and we are going to base the entire winter diet plan and ultimately animal performance on a sample that is less than half a kilo in weight. What we sample could represent less than 0.0001% of the total silage in the yard.
Therefore, the sampling technique needs to be accurate. Pits need to cored multiple times to get a composite sample that will somewhat reflect the average silage on the farm. Talk to your feed representative or agricultural consultant about getting proper tests done this winter.
Some feed companies are now operating handheld NIR (near-infrared spectrometry) machines that will analyse a sample on-farm. This can be a useful indication of the quality of silage being fed at that particular time, but should not be the sole method used for feed analysis.
Silage samples are not expensive – where you are looking for performance from your silage in the form of liveweight gain or milk production, I would recommend testing silage twice or three times throughout the winter period.
Where dry cows are being fed, the importance of this is lessened but not eliminated.
Research carried out some years ago in Teagasc Grange looked to investigate the losses, both in quality and quantity, of silage from being mown in the field to being delivered to the animal during winter. It found that for every 1,000kg of grass DM in the silage sward, between 150kg/DM and 300kg/DM never made it to the animal’s mouth as silage.
Also, the digestibility of the silage offered could be anywhere from 0% to 7% units below the digestibility of grass at the point of mowing, depending on the level of management.
These losses occur at the time of ensiling – through respiration, leaching by rain and incomplete pickup – but also during feedout due to silage heating and poor pit-face management.
Once pits are open, you should be cutting the entire face of the pit at least once every 10 days. Where it takes longer than this, heating will start to occur, which will lead to losses.
Where silage is heating it is burning the energy in the feed – this is energy that we need to deliver to the animal. Pits should be cut with a well sharpened shear grab or blockcutter to minimise the amount of air introduced to the pit face.
Keep the pit face as smooth as possible to reduce the surface area that air can be introduced to the pit.
Where the pit face is too wide, taking half-grab depths will increase the speed at which you clear each bench of silage.
When cattle start to be housed for winter, it is useful to have baled silage to use until there is a sufficient number of stock housed to open the pit.
The next area to focus on is the feed trough or feed passage. Feed troughs are brilliant at keeping feed at the animal’s head at all times, but they need to be cleaned out regularly. Feed should be allowed to run low prior to filling the trough once again and each trough should be cleaned out completely at least once a week. Placing new feed on top of stale feed will lead to greater feed losses, as animals will not clean out troughs as well as they should.
Likewise, feed passages need to be cleaned out at least once a week. Where silage is being put in a centre passage for a few days, it is better to do this at least twice a week.
While from a labour point of view it may be easier to fill the passage at the weekend for the week ahead, it can lead to greater spoilage of feed and a lower feed value silage being offered to stock for the last couple of days.
Where silage is not being fed ad lib, there needs to be enough space for every animal to eat at the same time. This means a feed space of 600mm to 650mm per cow, depending on cow size.
The next thing to consider is the feed rail height. In many sheds, the feed rail is set to the height required to stop the smallest animal in the group escaping from the pen. What this means is that the rail is too low for the majority of animals in the pen. This can lead to poorer intakes due to feeding discomfort.
Having feed barriers will overcome this problem, but for sheds with a feed rail, stock should be housed according to size and the feed barrier height adjusted accordingly.
If stock in the shed have marks or lumps on their necks from the feed rail, then there is an issue with either the height of the rail, the level of the feed surface or the amount of feed that is being offered to stock.
In terms of improving animal performance, this is one area that can sometimes be overlooked. Having a constant supply of fresh, clean water available to animals at all times can transform animal performance and should not be underestimated.
Troughs should be checked twice daily to ensure they are clean and working. Place water troughs towards the front of the shed so that they can be seen from the feed passage without having to get into the pen to see them.
At the same time, avoid having them over or right beside the feed face, as some animals will spill out water on the feed, which can lead to greater spoilage.