Using long-term averted goats for selective grazing in olive groves

Area of Science:

• Animal Science
• Behavioral Ecology
• Agricultural Science

Background:

• Conditioned taste aversion (CTA) is a viable strategy for modifying livestock grazing behavior, crucial for weed control in agricultural settings.
• Lithium chloride (LiCl) is a common agent for inducing CTA, but its long-term efficacy in small ruminants requires further investigation.
• Limited research exists on the persistence of LiCl-induced CTA in goats, particularly concerning its application in managing grazing habits around valuable crops like olive trees.

Purpose of the Study:

• To evaluate the effectiveness and long-term persistence of two LiCl doses (175 mg/kg BW and 200 mg/kg BW) in establishing CTA to olive tree leaves in dairy goats.
• To assess the impact of LiCl-induced CTA on selective grazing behavior and consumption of olive leaves under both controlled and on-field conditions.
• To determine the optimal LiCl dosage for achieving sustained aversion and facilitating weed management in olive orchards without compromising fruit production.

Main Methods:

• Fifteen non-lactating dairy goats were assigned to three groups: control (C, 0 mg/kg BW), AV1 (175 mg/kg BW LiCl), and AV2 (200 mg/kg BW LiCl).
• Aversion was induced with a single LiCl dose, with reinforcement on day 9 if necessary. Mid-term aversion was tested using choice feeding trials, and long-term aversion was assessed via grazing in simulated and commercial olive groves.
• Behavioral observations, including time spent consuming olive leaves and bipedal stance frequency, were recorded throughout the study period (up to 420 days).

Main Results:

• A single LiCl dose successfully induced CTA in all treated goats. CTA persisted for 4 days in the AV1 group and 55 days in the AV2 group (P<0.001).
• The 200 mg/kg BW dose (AV2) demonstrated superior long-term effectiveness compared to the 175 mg/kg BW dose (AV1), with fewer goats requiring reinforcement.
• Goats in the CTA groups, particularly AV2, significantly reduced olive leaf consumption and avoided contact with olive trees during grazing compared to control goats.

Conclusions:

• The 200 mg LiCl/kg BW dose is more effective than 175 mg LiCl/kg BW for inducing a robust and long-lasting conditioned taste aversion to olive tree leaves in goats.
• LiCl-induced CTA provides a promising, non-damaging method for selective grazing and weed control in olive orchards, contributing to sustainable agricultural practices.
• The findings support the use of CTA as a practical tool for managing livestock behavior and enhancing the efficiency of weed management in silvopastoral systems.