Enhancing nutrient efficiency through optimizing protein levels in lambs: Involvement of gastrointestinal microbiota

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Microbiology

Background:

• Optimizing nutrient utilization in ruminants is crucial for economic and environmental sustainability.
• Dietary protein levels significantly impact ruminant growth and nitrogen emissions.

Purpose of the Study:

• To investigate the effects of varying dietary protein levels on the growth performance, nutrient utilization, and gastrointestinal microbiota of Hulunbuir lambs.
• To determine the optimal dietary crude protein content for enhancing lamb productivity and reducing nitrogen excretion.

Main Methods:

• A 63-day feeding trial involving 24 Hulunbuir lambs subjected to low-protein (LP), medium-protein (MP), and high-protein (HP) diets.
• Measurements included growth performance, nutrient digestibility, serum biochemical parameters, and rumen and colon microbial composition and diversity.

Main Results:

• The MP diet (112.0 g/kg DM) resulted in superior daily weight gain and feed conversion ratio compared to the HP diet.
• MP diet enhanced crude protein and acid detergent fiber digestibility versus the LP diet.
• Dietary protein level modulated serum urea nitrogen, amino acid profiles, and rumen/colon ammonia and volatile fatty acid concentrations.
• Microbial diversity and structure were significantly altered, with specific beneficial bacteria enriched in the MP treatment's rumen and colon.

Conclusions:

• A medium-protein diet (112.0 g/kg DM) optimizes growth performance and nutrient utilization in lambs.
• The observed improvements are linked to beneficial shifts in the gastrointestinal microbiota composition and function.
• This dietary strategy offers a promising approach for sustainable ruminant production.