Recently a CAFRE dairy business development group (BDG) based in the east of the province met to discuss winter rations. Silage quality has been variable across the province, with some first cut forage on the low side for energy and others struggling with high NDF (neutral detergent fibre) and poor digestibility (D-value).
Recent analysis from AgriSearch’s GrassCheck grazing quality data would suggest that across the province, grass quality was significantly depressed for much of the 2022 grazing year. In May particularly, when many farmers were trying to get first cuts into clamps, grazing grass analysed at 16.9% Dry Matter, 15.9% Crude Protein and 10.8MJ Metabolizable Energy. In comparison to the grazing quality data from 2021, where Dry Matter in the same month was 19.4%, Crude Protein was 15.32% and Metabolizable Energy averaged 12.03 MJ, it is easy to see why we are now dealing with significantly poorer quality silages this year when compared to last year.
Lack of sunshine and an abundance of rain in the early part of the year have therefore had a negative influence on quality, with lower sugar levels at the time of cutting and a larger proportion of the plant coming in as stem due to a delay in harvest date.
These high NDF, low ME silages require more ‘effort’ from the cow to breakdown in the rumen, leaving less energy for the cow to use in milk production. Getting energy balances right this winter will be crucial, especially if farmers are to maintain healthy rumen function and, as we move closer to breeding season for the autumn-calving herd, cow fertility and conception rates.
At a recent CAFRE Dairying BDG meeting on the farm of Richard Brown, Millisle, the group heard from David, a nutritionist working with silages this winter.
“Take account, test regularly and make best use of the silage in your clamps”, was the overarching theme of the day. David advised that “Our milk cows are our VIC’s (Very Important Cows!) and they should be given priority when it comes to allocating forage this winter. The group were asked to keep feed fresh at the barrier and clear away waste daily to minimise the chance of spoilage of new feed. Direct your best quality feed to your milk cows and combine cuts if possible to hit targets in terms of dry matter, fibre, energy and protein. Spoilt silage should be discarded as mixing even a small amount of this into a ration can lead to refusals and issues with mycotoxins.”
The farmers were reminded that the silage in their clamps is some of the most expensive forage they have ever made, but despite that, silage remains a cheaper alternative to purchased concentrates. Minimising waste and utilising as much of that ensiled forage as possible is key, making sure to target the right silage to the right animal throughout winter.
With regards to feeding concentrates, and a significant element of feed-price volatility, David explained it could be tempting to go for cheaper ration ingredients but this could present a false economy. Paying close attention to mineral levels will also pay dividends. Minerals are involved in every process within the cow and an imbalance could present issues with performance, health, the immune system and fertility.
Silages that are heating and spoiling at the face quickly are problematic, these silages will generally be high in toxins and causing issues, even if you can’t see them! David advised the group to talk to their nutritionist or advisor about the use of a toxin binder to minimise the effect of these silent killers. If this is a recurring problem on your farm (year on year), consider the use of a silage additive next year. For management this year, maintain a sharp and tight feed face to minimise any further aerobic spoilage.
Focus on Fibre
Ruminants have a unique ability to make use of a significant amount of energy from the fibre in forage. This fibre is made up of three components, cellulose, hemi-cellulose and lignin, of which only cellulose and hemi-cellulose are digestible in the rumen. Forages that have been delayed in their cutting and were therefore more mature when harvested will be high in lignin. This can present problems with digestibility. High NDF silages may require additives to help fibre breakdown in the rumen. Yeast or enzymes can aid fibre digestion and thus allow for a quicker release of the energy that the cow needs.
Why consider Rumen Buffers
Low pH (or very acidic) silages are also a potential problem this year. Having a low (and decreasing) pH is an indication of secondary fermentation within the clamp and can lead to problems with palatability and silage intakes. Feeding little and often can help, with plenty of feed space to reduce competition at the barrier. Including a rumen buffer in the TMR can also help to reduce peaks and troughs in rumen pH and reduce the risk of acidosis.
Anna Truesdale finished the meeting by concluding that “improving the feeding value of grass silage is a constant challenge on dairy farms. The production of high intake, high digestible grass silage, capable of supporting high levels of milk will continue to be the cornerstone of winter milk production. Those who consistently make the best quality silage each year ensure the basics are adhered to and no short cuts are taken. Remember it takes the same fertiliser, diesel and contractor costs to make average silage compared to top quality material without the benefits.”
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