Population shifts in some faeces and rumen bacteria profiles and subsequent blood LPS and lactate concentrations in lambs in the early period of subacute ruminal acidosis.

Background: It is known that ruminal acidosis can induce harmal population shifts in some ruminal bacteria profiles. However, there is little information related to alterations in faecal and ruminal bacterial communities and relevant serum lipopolysaccharide (LPS) in sheep with subacute ruminal acidosis (SARA).

Objectives: This study aimed to investigate alterations in the defined faecal and ruminal bacteria profiles and serum LPS and blood lactate concentrations in lambs with empirically induced SARA.

Methods: Fifteen lambs were served and undergone to induce SARA during a 7-day period. Faecal and ruminal samples were taken to measure the pH and to perform the bacteriological works at 0 (just before induction), 8, 9, and 10 days of the challenge. Blood samples were collected to determine the serum LPS and lactate levels. The rumen and faecal samples were cultured to specify colony-forming units (CFU) for Escherichia coli, Streptococcus Group D (SGD), and lactic acid bacteria (LAB).

Results: Serum LPS value had no significant increase in the affected lambs with SARA. Significant increasing trends were observed in faecal E. coli and LAB populations (p < 0.01). Rumen bacteriology revealed a rising trend for LAB and a falling trend for SGD populations (p < 0.01).

Conclusion: Unlike cattle, LPS appears to be of minor importance in the pathogenesis of SARA in sheep. The increased ruminal and faecal LAB (4.00 × 10 CFU/ml or g) are proposed as valuable biomarkers for improving nutritional strategy and screening SARA in lambs.