Changes in faecal bacteria associated with concentrate and forage-only diets fed to horses in training.
BACKGROUND
Diets rich in readily fermentable carbohydrates, fed traditionally to meet the increased energy requirements of the performance horse, are associated with a number of gastrointestinal disorders that involve disturbances in the intestinal microbiota, however, these changes are poorly understood.


OBJECTIVE
With the long-term objective of improving intestinal health and to increase understanding of the relationship between diet and microbiota, the effect of feeding Standardbred horses a high-energy forage-only (F) diet was studied compared to a more traditional forage-concentrate (C) diet on faecal microbiota.


METHODS
Diets were fed in a cross-over design to 6 mature geldings on a scheduled training regime, both periods consisting of 29 days. DNA was extracted from faecal samples collected at 4 time points from each period, bacterial 16S rRNA genes were amplified and community composition assessed by terminal-restriction fragment length polymorphism, cloning and sequencing. Faecal pH and cultivable lactic acid bacteria (LAB) and enterobacteria were also assessed on the final collection day of each period.


RESULTS
Diet F resulted in a microbial composition that was more stable between sampling periods and had lower counts (P < 0.05) of cultivable LAB and specifically members of the Streptococcus bovislequinus complex. Motile and swarming Lactobacillus ruminis was present in all horses on diet C and not in horses on diet F. Diet C also resulted in the increase (P < 0.05) in members of Clostridiaceae cluster III and a concomitant reduction (P < 0.05) in an unknown group of Bacteroidales.


CONCLUSIONS
The greater microbial stability and reduction in LAB and members of the Streptococcus bovis/equinus complex on diet F indicate an opportunity to develop feeding strategies that support equine health and welfare. Novel changes identified in the faecal microbiota that resulted from carbohydrate inclusion merit further investigation.
Willing
B
B
Department of Microbiology, P.O. Box 7025, Swedish University of Agricultural Science, 75007 Uppsala, Sweden.
Vörös
A
A
Roos
S
S
Jones
C
C
Jansson
A
A
Lindberg
J E
JE
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification; D018592:Cross-Over Studies; D004032:Diet / Q000662:veterinary*; D005243:Feces / Q000382:microbiology*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D008297:Male; D010802:Phylogeny; D010805:Physical Conditioning, Animal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S