Given how quickly quality declines with grass maturity, harvesting the first cut of haylage is BY FAR a much higher priority than planting corn at this point. Quality lost due to excessive maturity can only be compensated for with purchased feed. Given that scary proposition, little more needs to be said. For a refresher on top-quality haylage production, please refer to Haylage Production Practices to Reduce Your Grain Bill https://agronomator.wordpress.com/2012/03/14/haylage-production-practices-to-reduce-your-grain-bill-by-daniel-hudson/
A presentation used in our winter meetings called Making Hay[lage] While the Sun Shines can be viewed at: https://agronomator.files.wordpress.com/2012/03/haylage-in-a-day-2.pdf
If you have any interpretive questions about the presentation, please do not hesitate to contact me at firstname.lastname@example.org or 802-751-8307.