Managing Nutrient Gaps as Pasture Quality Changes Through Spring

Managing Nutrient Gaps as Pasture Quality Changes Through Spring

Spring is a season of abundance for horse owners. After the dry, hay-heavy months of winter, fresh green pastures are a welcome sight — full of lush growth, improved palatability, and renewed grazing opportunities. But beneath that vibrant carpet of green lies a nutritional challenge that often goes unnoticed: pasture quality doesn’t stay constant. It shifts significantly from early to late spring, and those changes can leave nutrient gaps in your horse’s diet that affect everything from energy levels and hoof quality to immune function and digestive health.

Understanding how and why pasture composition changes — and what that means for your horse — is key to keeping them healthy and thriving throughout the season.

The Spring Pasture Curve: From Rich to Depleted

Spring growth follows a predictable pattern. In the early weeks, when soil moisture is high and temperatures are mild, grass grows rapidly. During this phase, pastures are often rich in sugars (non-structural carbohydrates, or NSCs) and water-soluble vitamins. Horses tend to love this sweet, tender forage — but it’s not without its challenges.

As spring progresses, temperature, rainfall, and plant maturity start to shift the nutrient profile:

• Early Spring: High sugar, low fibre, moderate protein, variable minerals

• Mid-Spring: Balanced sugar and fibre, higher protein, moderate to high mineral availability

• Late Spring: Lower sugar, higher fibre (less digestible), declining protein and mineral content

By the time you’re into late spring or early summer, your once nutrient-dense pasture can become energy-dilute and mineral-imbalanced, even if it still looks green and plentiful.

Why Nutrient Gaps Matter

Horses rely on a consistent supply of key nutrients to maintain condition, support their immune systems, build muscle, grow strong hooves, and sustain gut health. When those nutrients fluctuate with pasture changes, so does their physiological balance.

Here are some of the most common nutrient gaps that develop as spring progresses:

1. Declining Protein Quality and Quantity

In the early part of spring, rapid pasture growth provides plenty of crude protein, often exceeding requirements for maintenance horses. However, as plants mature, protein levels drop and the amino acid profile becomes less balanced. Lysine, an essential amino acid critical for muscle development and growth, is often the first to become limiting.

Why it matters:
Low-quality or insufficient protein can lead to loss of topline, poor muscle recovery after work, slower growth in young horses, and compromised immune function.

How to manage it:

• Consider adding a high-quality protein source (like soybean meal or a balanced balancer pellet) to your horse’s ration.

• Ensure the diet includes essential amino acids, especially lysine, methionine, and threonine.

2. Mineral Imbalances: Calcium, Phosphorus, and Beyond

Rapidly growing spring grass is often high in potassium but low in sodium and magnesium, creating potential electrolyte imbalances. As the season continues, calcium, phosphorus, zinc, and copper levels may also fall below ideal levels, especially in heavily grazed or unimproved pastures.

Why it matters:

• Calcium and phosphorus imbalances can impact bone health, muscle function, and metabolic processes.

• Zinc and copper are vital for hoof integrity, coat condition, and immune health.

• Low magnesium is linked to excitability and poor nerve function.

How to manage it:

• Provide a free-choice salt lick or add electrolytes to the diet to balance sodium and potassium.

• Use a broad-spectrum mineral supplement or feed balancer formulated for Australian pasture conditions.

• Check feed labels to ensure trace minerals are supplied in chelated or organic forms for better absorption.

3. Reduced Vitamin Content Over Time

Fresh grass is an excellent source of vitamins A, E, and K — but levels can decline as plants mature or if pasture is overgrazed and regrowth slows. Horses with limited grazing time may not consume enough to meet their daily requirements, especially those in work or breeding stock with higher demands.

Why it matters:

• Vitamin E is a powerful antioxidant essential for muscle and nerve health.

• Vitamin A supports vision, immunity, and reproductive function.

• Deficiencies can lead to subtle but significant health issues over time.

How to manage it:

• Supplement vitamin E if your horse is in regular exercise, particularly if pasture quality is declining.

• Provide a comprehensive vitamin and mineral mix if pasture alone can’t meet their needs.

4. Fibre and Digestive Function

Spring pasture is often low in structural fibre, particularly in the early flush when grass is soft and leafy. While highly digestible, this lack of fibre can disrupt the hindgut’s microbial balance and reduce fermentation efficiency. As the season progresses, fibre levels increase — but often at the expense of digestibility, leaving horses struggling to extract enough energy.

Why it matters:
Fibre is critical for gut health, hydration, and steady energy release. Rapid changes in fibre content can increase the risk of colic, diarrhoea, or behavioural issues linked to hindgut disruption.

How to manage it:

• Maintain a consistent source of long-stem fibre (e.g. hay) even when pasture is abundant.

• Introduce changes gradually to allow the gut microbiome to adapt.

• Consider a prebiotic or yeast culture to support digestive stability.

Tailoring Nutrition to the Season

Because pasture is dynamic, nutritional management needs to be proactive, not reactive. The best strategy is to monitor your horse’s condition and your pasture quality regularly — and adjust the diet as needed.

Practical tips:

• Body condition scoring: Check weight and fat distribution every 2–3 weeks.

• Manure monitoring: Loose manure can signal rapid changes in forage composition or lack of fibre.

• Pasture assessment: Note changes in growth stage, colour, and density.

• Supplement strategically: Use a vitamin/mineral balancer year-round to fill predictable gaps.

The Take-Home Message

Spring pastures are a nutritional blessing — but they’re also a moving target. As the weeks pass, shifting grass composition can quietly create nutrient gaps that compromise your horse’s health, performance, and wellbeing. By understanding how those changes unfold and proactively supporting your horse with balanced nutrition, you can enjoy the best of spring without the seasonal pitfalls.

Ultimately, the green grass you see isn’t the whole story. With thoughtful feeding management and the right nutritional support, your horse can truly thrive — from the first spring sprout to the last days of summer growth.