Sward structure driven by light interception controls grazing efficiency in BRS Zuri guinea grass pastures

Area of Science:

• Pasture management
• Animal nutrition
• Rangeland ecology

Background:

• Pre-grazing light interception (LI) influences pasture structure and animal grazing behavior.
• Understanding LI's impact is crucial for optimizing forage production and utilization.

Purpose of the Study:

• To evaluate the effects of different LI levels on zuri grass structure.
• To assess the impact of LI on defoliation dynamics and animal foraging behavior.
• To determine optimal LI for maximizing pasture productivity and grazing efficiency.

Main Methods:

• Four LI levels (80%, 85%, 90%, 95%) were applied to zuri grass paddocks.
• Grazing trials were conducted for 24 hours with defoliation assessed at multiple time points.
• Key variables included grazed area, defoliation frequency and severity, bite rate, and steps between feeding stations.

Main Results:

• Defoliation frequency and severity increased linearly with higher LI, especially on expanded leaves.
• Bite rate and steps between feeding stations decreased linearly with higher LI, indicating reduced foraging effort.
• 90-95% LI resulted in greater forage mass, higher stocking rates, and improved forage utilization efficiency.

Conclusions:

• Managing zuri grass at 90-95% LI optimizes pasture structure.
• Higher LI levels enhance forage utilization efficiency and support higher stocking rates.
• This management strategy is recommended for intensive grazing systems.