Something is missing. It should be difficult to lose, yet on the average dairy farm, there are typically a couple of tonnes of dry matter that cannot be accounted for!
A gap exists between what we can grow on the farm and what we see in the tank. This article challenges the value of that gap in cash and in reduced carbon footprint, explores why it happens, and discusses what we can do about it.
Grow for it!
In a temperate climate blessed with warmth, sunlight, and moisture, we can grow significant amounts of dry matter. The chart below, extracted from AHDB’s RB209 (the industry’s fertiliser bible), indicates that farms in prime grass-growing sites can achieve over 12 tonnes of dry matter per hectare (tDM/ha) with proper crop nutrition and harvesting techniques. Additionally, by employing forage crops, top-tier grazing management, and the right genetic materials, achieving more than 14 tDM/ha is feasible, weather permitting.
The N rate in this chart refers to fertiliser, but the N could be from dilligent use of manures and a nice bit of clover 🙂
Achieving optimal growth of dry matter on a farm is often the straightforward part. The challenge lies in retaining this dry matter and converting it into saleable milk and meat!
Utilisation
The term ‘Utilised Dry Matter per hectare’ might sound more complicated than it actually is. It simply refers to the amount of dry matter utilised by the cows for milk and maintainance that was grown on the farm.
To work out how much dry matter the cows have utilised we can use the following calculation.
(energy used for maintainance and milk production – energy brought onto the farm) / average forage ME
For those who are particularly interested, it’s possible to delve into greater detail with very accurate values. While this might adjust the numbers by a few hundred kilograms, a rough estimate is sufficient to begin exploring how we can reclaim some of this elusive dry matter.
A basic version of the calculation is built into the calculator below. Try it out with your figures.
The default values are based on UK average Dairy Costed herds. The difference between what we can grow and what is utilised adds up to a lot of feed. there is always some DM losses that cannot be avoided. These are factored into the calculation so the difference between grown an utilised is mostly up for grabs.
Most of this missing DM is made up for by buying in purchased feed. What would it cost to buy this in?
Recaputuring the DM!
So, where does the dry matter go? The list below isn’t exhaustive but it highlights the main culprits we need to challenge:
- Not growing what we think – it could simply be that we are not growing enough. This could be due to some fields underperforming or it could be our grazing management.
- In-field losses – During silage making some forage can be left in the field. This is shown in the chart below as In Field.
- Ensilement losses – Also shown in the chart above, a fair bit of dry matter can be leached, respired or fermented away. Ultimately attention to detail in silage making pays every time. Shorts are expensive. Keep it clean, roll, roll, roll, use an effective additive, sheet tight and weigh down evenly and avoid letting heifers walk over the top of the clamp!
- Face losses – Clamp management is a critical area where a significant amount of DM can be lost. Not only is there visible waste, but a lot more DM can also be lost as CO2 streaming from the bottom of the clamp.
- Feed-out losses – Getting the proportion of PMR/TMR just right can help avoid wastage. Also, its suprising how much those pesky starlings take!
- Digestion – This one is a biggie. If your dung pats look like little thatched cottages, then for sure that dry matter hasn’t contributed to the tank. Balance the diet and stick some yeast in. The rumen needs to burn hotter.
- Passengers – Hiding in plain sight within the herd are some animals whose FCE is DOA and they are not FOC. There is little in the tank to show for the dry matter they eat.
- Cake reps – There are some (not all!) who don’t optimise the forage dry matter intake when rationing the cows. Feeding too much cake will eat away at Utilised Dry Matter. Use the What-If? Tool to check where you are on the Milk Map. If you are near the bottom there is a conversation to be had 🙂
Recapturing some of this lost dry matter will not only help the bottom line of the business but it will also significantly reduce the farm’s carbon footprint.
If a kilogram of purchased feed has a carbon footprint of 1kg. Then that is how many tonnes you could save.
The key limitation is forage dry matter intake potential and digestibility. More Dairy Club articles on this will follow.
It’s an important part of your action plan.