Effects of Dietary Slow-Release Urea Supplementation on Rumen Fermentation Parameters and Bacterial Populations in Lambs: Implications for Meat Production Efficiency

This study investigated the effects of dietary SRU supplementation at varying concentrations on rumen fermentation parameters and bacterial populations in Arabi lambs, thereby addressing knowledge gaps relevant to both animal nutrition and subsequent meat quality attributes. Sixteen male Arabi lambs (initial body weight ۲۲.۵ ± ۱.۱ kg; age ۴–۵ months) were randomly assigned to four dietary treatments over a ۱۰۵-day experimental period, including a ۱۵-day adaptation phase. Lambs received either a control diet (no SRU) or diets supplemented with SRU at ۱.۰%, ۱.۵%, or ۲.۰% of dry matter intake. Rumen fluid pH remained unaffected by SRU inclusion across all treatment levels (P > ۰.۰۵), indicating maintained rumen homeostasis. However, total bacterial counts increased significantly in lambs receiving ۲.۰% SRU (۸.۱۲ log₁₀ CFU mL⁻¹) compared to control and lower supplementation groups (P < ۰.۰۵). Similarly, populations of cellulolytic and proteolytic bacteria were significantly elevated in the ۲.۰% SRU treatment. Conversely, amylolytic bacterial counts exhibited a declining trend with increasing SRU concentration, decreasing from ۶.۷۴ log₁₀ CFU mL⁻¹ in controls to ۶.۶۴ log₁₀ CFU mL⁻¹ at ۲.۰% SRU. Total volatile fatty acid (VFA) concentration increased progressively with SRU inclusion level. Acetic acid concentration reached ۴۳.۰۹ mmol L⁻¹ in the ۲.۰% SRU treatment, representing a significant elevation relative to controls; parallel increases were observed for propionic and butyric acids. These findings demonstrate that dietary SRU supplementation, particularly at ۲.۰% inclusion, enhances rumen fermentative capacity through selective stimulation of cellulolytic and proteolytic bacterial populations and elevated VFA production, without compromising rumen pH stability.

کلیدواژه ها:

Slow-release urea ، Arabi lambs ، Rumen fermentation ، volatile fatty acids ، cellulolytic bacteria ، Meat Quality ، Feed efficiency