Low NDF feeds - managing the post seed-head phase

What is NDF Feed?
Neutral Detergent Fibre (NDF) is a measure of the fibre content of pasture and feeds that influences how much cows can eat and how easily that feed is digested. As NDF increases, particularly during the ryegrass seed‑head phase, digestibility and intake can decline.

Managing feed quality through the ryegrass seed‑head period remains a challenge for many Canterbury dairy farms. Consistent observations across multiple seasons show that this period, typically from early to mid‑November, can be associated with reduced feed intake, body condition loss, and poorer reproductive outcomes as pasture Neutral Detergent Fibre (NDF) levels rise.

The focus of the low NDF mitigation is on the tactical, short‑term use of lower NDF feeds to help cows maintain intake and performance through this higher‑risk period, rather than pushing additional production.

As pasture NDF increases, digestibility declines and intake can become physically limited. Observed impacts during this phase can include:

• Drops in per‑cow milk production
• Increased mobilisation of body reserves
• Reduced conception and in‑calf rates
• Flattening or declining milk protein percentages (an indicator of reduced energy intake)

The approach being developed recognises that low NDF feeds are typically more expensive, so their use must be carefully targeted and well justified. The emphasis is on:

• Maintaining pasture utilisation and harvest efficiency
• Avoiding forcing cows to consume high‑NDF residuals
• Using supplements selectively, only when response rates are likely to be high
• Supporting pasture testing and informed, timely feed decisions

This mitigation is being supported by MRB modelling to understand how tactical NDF use may fit within individual farm systems, with a strong focus on profitability, per‑cow performance, and emissions intensity outcomes. Wider system factors, such as transition feeding, calving performance, rumen adaptation, and pasture demand, are considered alongside feed decisions.

The goal is not a one‑size‑fits‑all solution, but a clear decision‑making framework that helps farmers manage risk through the seed‑head phase while maintaining animal wellbeing and whole‑system.