Rumen microbial and fermentation characteristics are affected differently by bacterial probiotic supplementation during induced lactic and subacute acidosis in sheep.
BACKGROUND
Ruminal disbiosis induced by feeding is the cause of ruminal acidosis, a digestive disorder prevalent in high-producing ruminants. Because probiotic microorganisms can modulate the gastrointestinal microbiota, propionibacteria- and lactobacilli-based probiotics were tested for their effectiveness in preventing different forms of acidosis.


RESULTS
Lactic acidosis, butyric and propionic subacute ruminal acidosis (SARA) were induced by feed chalenges in three groups of four wethers intraruminally dosed with wheat, corn or beet pulp. In each group, wethers were either not supplemented (C) or supplemented with Propionibacterium P63 alone (P) or combined with L. plantarum (Lp + P) or L. rhamnosus (Lr + P). Compared with C, all the probiotics stimulated lactobacilli proliferation, which reached up to 25% of total bacteria during wheat-induced lactic acidosis. This induced a large increase in lactate concentration, which decreased ruminal pH. During the corn-induced butyric SARA, Lp + P decreased Prevotella spp. proportion with a concomitant decrease in microbial amylase activity and total volatile fatty acids concentration, and an increase in xylanase activity and pH. Relative to the beet pulp-induced propionic SARA, P and Lr + P improved ruminal pH without affecting the microbial or fermentation characteristics. Regardless of acidosis type, denaturing gradient gel electrophoresis revealed that probiotic supplementations modified the bacterial community structure.


CONCLUSIONS
This work showed that the effectiveness of the bacterial probiotics tested depended on the acidosis type. Although these probiotics were ineffective in lactic acidosis because of a deeply disturbed rumen microbiota, some of the probiotics tested may be useful to minimize the occurrence of butyric and propionic SARA in sheep. However, their modes of action need to be further investigated.
INRA, UR1213 Herbivores, Centre de Recherches de Clermont-Ferrand/Theix, F-63122 Saint Genès, Champanelle, France.
Abderzak
A
Lettat
Pierre
P
Nozière
Mathieu
M
Silberberg
Diego P
DP
Morgavi
Claudette
C
Berger
Cécile
C
Martin
D000138:Acidosis / Q000517:prevention & control / Q000662:veterinary*; D000818:Animals; D027461:Beta vulgaris; D004032:Diet / Q000379:methods*; D005285:Fermentation; D052201:Lacticaseibacillus rhamnosus / Q000502:physiology; D019936:Probiotics / Q000008:administration & dosage*; D011424:Propionibacterium / Q000502:physiology; D012417:Rumen / Q000382:microbiology* / Q000503:physiopathology; D012756:Sheep; D012757:Sheep Diseases / Q000517:prevention & control*; D016896:Treatment Outcome; D014908:Triticum; D003313:Zea mays