Dietary energy enhances conception in Holstein heifers via interactions with rumen microbiota

Area of Science:

• Animal Science
• Reproductive Biology
• Microbiome Research

Background:

• Dietary energy levels significantly influence reproductive performance in livestock.
• Understanding rumen microbiota-host interactions is crucial for optimizing animal health and productivity.

Purpose of the Study:

• To investigate how graded dietary energy levels regulate the hypothalamic-pituitary-gonadal (HPG) axis in Holstein heifers.
• To explore the role of rumen microbiota-host interactions in mediating these effects during initial breeding.

Main Methods:

• Forty-four pubertal Holstein heifers were assigned to control or high-energy diets.
• Evaluated growth performance, serum markers (biochemical, immune, antioxidant), reproductive hormones, and rumen parameters (fermentation, microbiota, metabolome).

Main Results:

• High-energy diets elevated gonadotropins (FSH, LH) and prolactin (PRL), indicating enhanced HPG axis activity.
• Observed increased serum triglycerides, altered immune markers (e.g., increased IL-2, IL-6; decreased IL-4, TNF-α, IFN-γ), and improved antioxidant capacity (lower MDA).
• Rumen analysis revealed decreased pH, elevated volatile fatty acids (VFA), bacterial crude protein (BCP), and specific microbial shifts (e.g., Treponema, Prevotellaceae_UCG_003, Ruminococcus) correlated with hormonal and metabolic changes.

Conclusions:

• High-energy diets enhance hypothalamic-pituitary signaling and rumen fermentation efficiency in heifers.
• This dietary strategy advanced first-service conception rates by 15% in pasture-based systems.
• Optimizes reproductive management in intensive dairy operations via microbiota-driven metabolic modulation.