Plenty of Grass, But Are Cows Getting What They Need?

Spring grass is high in moisture, rapidly fermentable carbohydrates, and crude proteins that can be higher than optimal. This comes at a time when freshly calved cows will have limited rumen capacity, yet very high nutrient demands.

Even when cows are eating a lot of grass, they may still fall short on dry matter, energy, and key minerals. High water content and a lack of fibre also mean rapid passage through the gut, allowing less time for digestion and absorption; the result is an intake gap at the very time when feed seems so plentiful.

Mineral Levels Between Paddocks

Fast-growing pasture is also variable in mineral content. Magnesium, sodium and phosphorus levels can be low relative to the cow's needs, especially in early lactation. Trace elements such as selenium, cobalt and zinc are influenced by soil type and fertiliser history and can vary widely across paddocks.

High potassium in lush spring grass is a particular risk as potassium can interfere with magnesium absorption and raise the chance of hypomagnesemia. Even cows eating well can struggle to mobilise enough magnesium when potassium is high. In fact, pasture can deliver a wide range of mineral antagonists; commonly, high sulphur can affect available copper and selenium levels, and high iron levels common with soil-contaminated pasture also affect mineral availability to the cow.

Consistent Element Source

When pasture cannot reliably supply the minerals cows need, supplements provide a consistent source of those elements that help to support appetite, rumen function and the cow's ability to utilise the energy she eats. It is important to note that while minerals close some key nutritional gaps, they do not create calories or replace dry matter. They enable the cow to make better use of the feed she is given and reduce the risk of disease.

When Cows Fall Short

Signs cows may not be getting what they need include inconsistent appetite or rumination, loose manure, poor milk response to feed, falling milk protein or fat percentages, poor cow health, slow recovery after calving, loss of body condition and an increased incidence of metabolic issues.

Watch your cows closely and be on the lookout for subtle changes, like a drop in milk protein or uneven intakes at the feed pad. Any of these can be an early warning sign.

Beyond Paddock Appearance

Farmers should use multiple information sources rather than relying on paddock appearance alone. Useful checks include:

• Pasture and feed testing (can help quantify dry matter, metabolise energy and mineral levels so you can see what is actually available to the cow)
• Monitoring her milk yield and composition
• Scanning body condition
• Tracking rumination and other cow behaviour metrics
• Milk SCC levels
• Other cow health metrics such as metritis, RFMs, lameness, treatments etc.

Delivery of minerals must suit the farm system and ensure consistent access. There are options for all systems, including in-feed blends, water-based delivery, dusting, free-choice supplements, all of which can be tailored to your individual farm needs. Each method has pros and cons related to consistency, labour, and wastage. The best approach is the one that fits your system and reliably delivers the required minerals to the right cows at the right time.

Get A Plan In Place

When planning spring nutrition, ask what the pasture is supplying in dry matter, energy and minerals, and whether freshly calved cows are consuming enough dry matter to meet early lactation demand. Consider which minerals may be short or poorly absorbed, and whether supplementation intake is consistent across the herd and easy to monitor. Review herd history for patterns in milk composition, metabolic issues and spring health challenges.

Mineral planning should bee part of a wider spring feeding strategy. Ensure cows have adequate dry matter and energy through appropriate grazing management, buffer feeding where needed and making quality supplements available. Us mineral supplementation to plug the gaps that pasture cannot fill reliably. Work with your vet or nutritionist to interpret pasture tests and herd records and to design a delivery method that fits your system.

Match Pasture with Energy

Start by testing representative paddocks for dry matter, metabolisable energy and mineral levels.

Monitor milk test information constantly, looking at protein, fat, lactose, and MUN levels as these are very good indicators of feed balance.

Closely track body condition in freshly calved cows and introduce additional feed if it drops too far. Intake behaviour and rumination can also signal problems early.

Choose a supplementation method that provides consistent access and works for your team, and seek veterinary or nutrition advice if metabolic issues recur each spring.

Getting the most from spring is not simply about growing more grass. Think about matching pasture with the energy, fibree and mineral support your cows need to convert that feed into milk maintaining health and condition.

Chris Balemi is Agvance Nutrition founder and managing director.