After 35 years in the contracting business, and now focusing on growing and supplying quality maize and grass silage, he sees a broad range of quality in the course of a season.
For Webb, offering farmers certainty around grass silage quality is part of the service. He aims to ensure he maintains a targeted average of 11.5 megajoules of metabolisable energy per kg of drymatter (MJ ME/kg DM), and that it does not fall below 11.0MJ ME/kg DM.
“Good grass silage should contain around 11MJ ME/kg DM, but often due to weather delaying harvesting, or the desire to buy in bulk, the realistic figure falls to about 10mj me/kg dm.”
Webb maintained an average of 11.6MJ ME/kg DM for all last season’s baled silage, based on Hills Laboratories analysis.
‘The best point to make silage out of it is the point when you would be putting the cows back into it to graze.’
This compared to an industry average sampled in the lab of about 9.6MJ ME/kg DM.
“That alone indicates there is still considerable room for improvement in the sector, for a feed that still represents a pretty cheap but valuable supplement.”
Webb has spent years focusing on the magic numbers of 35% natural detergent fibre (NDF) and 12MJ ME/kg DM in his harvested silage. Those numbers will ensure a high dry matter intake is achievable, and can be done with good quality harvested silage and attention to preservation once in the stack.
The biggest pitfall Webb sees to maximising the feed value of silage is when farmers are tempted to let the grass grow too long, compromising quality for bulk.
“The best point to make silage out of it is the point when you would be putting the cows back into it to graze. The typical height would be about in line with the top of a Redband gumboot, at about 2500kg DM/ha cover,” he said.
Earlier work has suggested that a 10-15% seed head proportion in the silage is acceptable, but Webb is adamant the focus needs to be on good quality, leafy grass with no seed head in it.
“Making it with seed head suggests you are already too late in the season and have missed the opportunity to harvest a high quality supplement.”
This makes harvesting in September or early October almost essential for areas north of Taupo, while farmers on irrigated pasture further south could push that out later.
Leaving a paddock too long before harvesting will result in greater bulk, but compromise digestibility, pushing that below 65%, and possibly compromising protein value also.
“The simple question you have to ask before harvesting it is ‘would I feed that to my cows and expect them to milk well on it?’”
For baled silage a drymatter level up to 43% can be acceptable, making them easier to transport by holding their shape better, and reducing the amount of water being transported.
Webb cautions that treating with inoculants, while helping fermentation happen quicker, will not turn “bad silage to good”.
His concern is too many farmers simply consider making silage as a means of shoving an unwanted surplus towards the end of the season, rather than considering how to optimise the quality for more days in milk on it.
Steps to better silage
- Aim for NDF of 35% and a minimum of 11.0MJ ME/kg DM
- Harvest at 2500-3000kg DM/ha with high leaf content, no seed heads
- If buying-in silage bales request an analysis to better gauge quality
- Use inoculants to speed process. It will not make a poor crop better
- A purpose-built bunker will always be a better option for effective compaction, thanks to solid sides versus a stack
- Keep covered completely, with tyres touching and set bait traps for rats, fence for stock and check regularly for holes – protect your feed investment
- Ensure leachate is correctly captured from stack.
