Propionibacteria in Ruminant’s Diets: An Overview
Pionibacteria are natural inhabitants of the rumen that make up 1.4% of ruminal microflora and produce propionate, a major precursor for glucose production by hepatic gluconeogenesis. Several mechanisms have been suggested for the mode of action of direct-fed bacteria in ruminants include stimulation of desirable microbial growth in the rumen, alteration of ruminal fermentation pattern and end product formation, increasing postruminal nutrient flow, increasing nutrient digestibility and alleviation of stress through enhanced immune response. Propionibacteria have the ability to convert lactic acid and glucose to acetic and propionic acids, reduce the risk of acidosis and increase weight gain and milk production of treated animals. On the other hand, enteric CH4 is the single largest contributing source of greenhouse gases production which causes global warming crisis. Propionibacteria also act to alter the biohydrogenation of polyunsaturated fatty acids in the rumen and increasing the generation of health-promoting fatty acids such as Conjugated Linoleic Acid (CLA). The impact of feeding of propionibacteria on the performance of the ruminant animals has been evaluated but results were inconsistent, this may be attributed to many of factors involved the used bacterial strain and its viability, bacterial inclusion level in the diet, diet composition and frequency of feeding, animal status including age, breed, health and physiological condition. In this review the focus will be on surveying impact of feeding propionibacteria on the productive performance of the ruminants including the effects on nutrients digestibility, rumen activity, blood parameters, milk yield and milk composition.
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