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First-cut silage has now been analysed on all of the programme farms, with the results outlined in Table 1. Across all nine farms, silage quality is excellent, with higher energy, protein and D-Value when compared to previous years.
Over the course of the programme, the role of high-quality silage in reducing winter feed costs has been clearly demonstrated.
Several farms operating bull beef systems have typically fed around 5kg/day of concentrate, along with ad-lib silage during the growing phase.
This increases to a maximum concentrate feed rate of 8kg/day during the final 90-day finishing period, bringing lifetime concentrates fed to between 1.5t/head and 1.7t/head.
Stores and autumn-calving
Feeding high-quality silage has helped to increase weanling and store cattle performance over the winter period.
It has also benefited autumn-calving cows, helping to maintain milk production and high levels of fertility with minimal concentrate input.
A good example of this is on Barry Carty’s farm. Despite working on heavy ground outside Garrison, Barry has consistently made some of the best silage within the programme over the past three years.
Cattle sold back in February 2020 weighed 430kg to 440kg, rising from 350kg just two years ago
Spring-born calves are sold as yearling stores and a winter diet of high-quality silage, along with 2kg of supplementary concentrate, has seen sale weights increase year-on-year.
Cattle sold back in February 2020 weighed 430kg to 440kg, rising from 350kg just two years ago.
In addition, Barry’s autumn-born calves averaged 1.22kg/day on the cow over winter.
Replacement heifers
High-quality silage has also helped increase turnout weight in maiden heifers retained for breeding.
This has enabled these animals to reach target breeding weights, increasing the number of heifers calving down at 24 months old being successfully retained in the herd.
D-Value
As a group, the results make fantastic reading, with a D-Value averaging 73.92%, an increase of almost 1% from the 2019 D-Value of 73% and 3% from a D-Value of 70% in 2018.
A D-Value of 70% or higher reflects high-quality silage, with average- to good-quality silage having a D-Value of 66% to 69%.
D-Value is the level of digestible, organic matter within silage dry matter, and a good indicator of the nutritional content in fodder.
Basically, the higher the D-Value, the higher the feed value and the more easily digested the forage.
Every four-unit change in D-Value is the equivalent of feeding 1kg of concentrate
As D-Value increases, there is more energy and protein available to drive weight gain in growing cattle and milk in lactating cows. The D-Value falls as the sward matures and develops more stem and seed head.
Every four-unit change in D-Value is the equivalent of feeding 1kg of concentrate. Therefore, cattle eating 68% D-Value silage would require an additional 180kg of concentrate over a 180-day winter to achieve similar weight gains to cattle on 72% D-Value silage, at a cost of £40/head for a ration at £220/t
Farm comparison
At individual farm level, D-Value ranges from 71.65% to 78.41%. The results are reflective of the ideal weather conditions when silage harvesting took place in May.
Dry, settled conditions allowed the farmers to cut silage while it was mainly leaf. Grass was also wilted for 24 to 48 hours to increase dry matter and resulted in stable fermentation.
Yields
While quality is excellent, the dry spring had a negative impact on yields, with some farms seeing significantly less grass ensiled.
To avoid any potential fodder shortage, these farms have taken a third cut of silage and removed surplus grass from the grazing platform.
Offering the baled silage on an ad-lib-basis will limit concentrate requirement to just 3kg/day and should maintain a weight gain of 1.2kg/day
Analysis has shown that bales made from surplus grass usually have the best silage on-farm. For example, bales sampled on Alastair McNeilly’s farm had a D-Value of 78.75%.
These bales will be targeted to Limousin and Angus steers, which are closest to finishing. Offering the baled silage on an ad-lib-basis will limit concentrate requirement to just 3kg/day and should maintain a weight gain of 1.2kg/day.
Dry matter
Silage dry matter (DM) reflects how much water is in the forage. The target is to get silage to a DM between 30% and 40%, as this leads to a more stable fermentation, keeping ammonia and pH levels under control.
Wet silage is harder to ferment and intakes are lower. In contrast, extremely dry silage is also prone to heating when fed out. Across the farms, DM averaged 35%, up from 29.2% last year and 33.9% in 2018.
Energy and protein
The average energy value is 11.8 ME, which reflects the high levels of digestible leaf present in forage.
Crude protein averaged 15.38%, up from 14.3% last year and 12.2% in 2018. Protein is the main driver of weight gain in beef cattle and milk production in cows.
At the outlined figures for energy and protein in Table 1, there is scope to achieve weight gains of 0.6kg to 1kg/day in weanlings, without feeding any concentrate.
Where concentrates are offered, feed rates could be capped at 1kg/day. Higher rates can be fed, but will only substitute silage from the winter diet at a higher cost.
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