Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

Area of Science:

• Veterinary Parasitology
• Livestock Health Management
• Agricultural Science

Background:

• Pasture larval contamination monitoring is crucial for understanding parasitic nematode dynamics in livestock.
• Direct quantification of infective larvae (L3) on herbage is the standard method but is labor-intensive.
• Limited research exists on the impact of sampling methods and sample size on pasture larval count accuracy.

Purpose of the Study:

• To compare two herbage sampling methods (W-transect vs. random plots) for pasture larval contamination assessment.
• To evaluate the variation in larval counts across sample plots, pastures, and seasons.
• To determine the optimal sample size for estimating pasture larval contamination with desired precision.

Main Methods:

• Herbage samples were collected from eight dairy young stock pastures over three seasons (spring, summer, autumn).
• Method 1: Double-crossed W-transect sampling.
• Method 2: Four random plots (0.16 m²) per pasture, collecting all herbage within each plot.

Main Results:

• No significant difference in average infective larvae (L3)/kg dry herbage counts between the two sampling methods.
• Method 2 (random plots) required significantly less sampling time, especially on larger pastures (>1 ha).
• Variation in larval counts was primarily attributed to residual variance within seasons rather than pasture or seasonal effects.

Conclusions:

• Random plot herbage sampling (method 2) is a viable, time-efficient alternative for assessing pasture larval contamination.
• This method provides comparable results to traditional transect sampling with reduced labor.
• Further development of random plot sampling is recommended for routine pasture larval contamination monitoring.