Ranking lambs by feed efficiency - are there changes in ruminal fermentation parameters and enteric methane...

Area of Science:

• Animal Science
• Ruminant Nutrition
• Environmental Science

Background:

• Feed efficiency is crucial for sustainable livestock production.
• Reducing enteric methane (CH₄) emissions is an environmental priority.
• Understanding the link between feed efficiency and CH₄ production in lambs is essential.

Purpose of the Study:

• To investigate the impact of feed efficiency on ruminal fermentation and CH₄ emissions in Santa Inês lambs.
• To classify lambs into low, medium, and high feed efficiency groups using Residual Feed Intake (RFI) and Residual Intake Gain (RIG).
• To assess ruminal parameters and CH₄ output across different feed efficiency levels.

Main Methods:

• Forty Santa Inês lambs were grouped by feed efficiency (RFI and RIG).
• Experimental trials involved controlled feeding and individual CH₄ emission measurements.
• Ruminal fluid samples were collected for fermentation analysis and protozoa counts.

Main Results:

• No significant differences in dry matter intake, body weight, or CH₄ emissions were found among feed efficiency groups.
• High-efficiency lambs (RIG+) numerically showed 15.2% lower CH₄ emissions per kg of dry matter intake.
• Uniform diet may have masked significant differences in ruminal fermentation parameters.

Conclusions:

• Feed efficiency classifications (RFI, RIG) may be influenced by the animal's life stage.
• Classifications may lack consistency across different evaluation periods.
• While not statistically significant, a trend suggests higher feed efficiency could be linked to reduced CH₄ emissions.