Are You Ready to Beat the Drop?
The last month has been frustrating for many; lots of grass has grown over the winter period, yet the unpredictable weather has meant that farmers have not had any decent run at grazing in February. The main ‘burst’ of calving has settled down on many farms, and now the focus has shifted to milk production and the season ahead or, more importantly, milk solid production.
We must remember that our milk payment system is focused on kilograms of butterfat (BF) and protein. This is a function of milk yield and solids percentage. Our task is to maximise all of these and get the cow back on calf while keeping an eye on total cost.
If we look back at our milk recordings or co-op report for the year, a general theme runs through all of them. High percentage solids for the first six weeks, then a drop in protein, followed by a drop in butterfat heading into the second round of grazing. When analysing this data, it is more important to pay attention to the fluctuations rather than the overall level. For example, it is more worrying to see protein going from 3.5% to 3.25% rather than it being 3.3% all year. In the former, we are getting a negative change in diet or energy levels, which will have knock-on effects on body condition and fertility.
Keeping cows above 2 kg of milk solids (MS) for as long as possible is a target many should aim for, and this can be achieved in many ways, as outlined below:
26 litres at 4.0% BF and 3.5% Protein = 2kg MS
28 litres at 3.8% BF and 3.2% Protein = 2kg MS
It is important to remember the MS calculation for your own farm and complete the exercise regularly (detailed below). Milk production should fall no more than 1–2% per week post-peak. Analysis of your co-op report should see multiples of this during the May–July period, which is lost production but, more importantly, revenue.
(Milk yield litres/100) x (Fat% + Protein%) x 1.03
Protein is driven by the starch and sugar content of the diet, and the focus should be on this rather than increasing the energy alone. Starch is usually derived from a grain source in the concentrate, and the most abundant form of sugar over the next while will be grazed grass. Getting cows out to grass is important, as we see the effect of what going onto a better source of silage or forage can do to production levels. The focus should be on optimally utilising the first round of grass to retain quality in the sward in the subsequent rounds. While focusing on quality is one thing, we also need to pay attention to quantity, or dry matter intake (DMI). Cows need to be outside for the right reason and to consume grass in adequate conditions, rather than being outside to stand by the hedge or enjoy the scenery. Know your dry matter requirement and the amount they are getting from grass today. While a lot of farms shy away from grass measurement, at a minimum, you need to outline two figures. Supplements in the form of concentrate and forages need to be used and based on demand of feed, based on the cow/milk solids production. While protein levels will be spectacular on many farms during the first six weeks, this can be propped up by body condition losses. This means that each farm needs to assess its feeding regime, especially if they have had sharp drops in protein percentages in the past.
Lower milk fat can be due to several reasons. While we usually associate it with a lack-of-fibre issue in the diets, it can be attached to a lack of energy in the diet, or if cows are grazing, then the discovery of fatty acids in grass can also have adverse effects. Linoleic acid, which is prevalent in most forage species, is especially abundant in lush grass and can lead to a higher-fat diet. This can cause reduced fibre digestion, lower rumen pH and, so, compromised rumen health. Ultimately, this can lead to a reduction in butterfat percentage. Data from research has shown that as little as 2 g of conjugated linoleic acid (CLA) in the rumen can cause a 20%-drop in butterfat.
If you are experiencing a lower butterfat percentage, then you first need to assess other issues/characteristics in the cows, such as manure consistency. It should not be loose or overly watery, but more like soft porridge in a grazing situation (slow clap sound).
Dropping butterfat can be somewhat unavoidable as our focus should be on grazing high-quality, lush grass. However, other issues, such as dropping milk yield, body condition or milk protein, reduced intake or poor cud-chewing, should be a cause for concern, and we do need to act to correct them. We can help by using other features to improve rumen health, because we know that if we do not look after rumen health, then the effect of the CLA on our butterfat percentage will be exacerbated. Avoiding rapid changes to any diet is essential. While the weather is unpredictable, adjust any dietary changes slowly and avoid sudden changes in rumen pH.
If forage-based buffer containing chopped straw is still needed or used, this has been shown to maintain butterfat in a grazing situation. If butterfat percentage is your goal, you could continue to feed this forage buffer, but you need to be conscious of the availability of grass. If it is not required from an intake point of view, you might be compromising quality later, i.e., it might not make sense to feed silage to make silage. Also, if you are feeding forage at a reduced rate, you need to make sure it is clean, free from heating, mould or mycotoxins. Usually, in the absence of this, you are feeding a parlour-based concentrate and grazed grass. The focus should be to stick to feeding levels of 0.1–0.15 kg max per litre, assuming enough grass. Beyond this, a supplementary forage is required, as your volume of concentrate could compromise rumen health. As the aim is to make up DMI with the concentrate, we should add digestible fibres, like pulp sources, to the concentrate.
The use of a live yeast, such as Yea-Sacc®, in the parlour concentrate, has been proven to improve fibre digestion and rumen pH in grazing situations (UCD trials). Yea-Sacc is the most widely researched live yeast culture for promoting rumen stability — helping cows avoid the variations in rumen pH that can interfere with DMI, fibre digestion and butterfat production. Talk to your feed and/or mineral supplier to ensure it is added to your concentrate.
The presence of 80–100 kg of lush grass, high in fatty acids, can be hard to counteract. Lower butterfat is an issue that could last 2–5 weeks in mid-lactation and does not effect the visual appearance of the cow. The solutions above outline how we can improve the rumen environment so that we are not severely impacted by it and ultimately improve butterfat percentage. In fact, if implemented well and acted on as quickly as possible, it will go a long way to beat the drop in the first place.