14 February 2017
Ever left perplexed by silage analysis? Those ones where apart from the name at the top nothing else seems familiar to what you see in the silage pit. Perhaps worse are the ones which are just a little bit out as they seem right, and so important financial decisions get based on them. If we are to ration to the demands of good dairy farms we must begin with accurate numbers. Otherwise we are wasting your time – and worse, inaccurate rations cost in lost production/excess feed.
We have been finding a better way. Forage analysis based on a service where the feed is dried and ground before being tested is much more accurate – removing the water removes a lot of the variability. Most UK analysis does not do this unfortunately.
An example of the difference this makes is fibre. Fibre is fundamental in dairy cow nutrition – it is measured as NDF in the lab. Having a dependable NDF number is the 1st essential to allow more precise cow performance at the higher ends of production. There is also much to learn about that NDF – does it break down quickly, slowly or never? We know that the fibre in different grass forages behaves differently, never mind maize or wholecrop. Fast digesting NDF drives milk yield while slow and indigestible NDF, whilst necessary for healthy rumens, slows and lowers intakes and yields. Innovation in silage analysis allows us to measure the digestibility of this NDF, estimating how it will perform in the rumen, and so balancing better rations. This is done through a process called in vitro analysis.
To do In Vitro testing rumen fluid is harvested from cannulated cows. This fluid is a source of the bacteria needed to ferment the NDF – the process which breaks fibre down which we want to measure.
Once collected the fluid is incubated with feed samples. How much NDF is left is measured;
- after 30 hours for the ‘fast’ NDF which will drive your milk yield
- after 120 hours for ‘slow’ NDF which will slow eating and rumen throughput at higher productions
- and after 240 hours for completely indigestible NDF – gut fill
We find these numbers give powerful information on the difference between silages, which were perhaps not always obvious before. Ultimately of course, the goal is increasing health and performance, and trouble-shooting when things are not right for the nutritionist. For the farmer it is information which informs and guides the production of better forage in the future. These are reasons better silage analysis is worth pursuing.