Focus on the use of ruminal microbiota as pro and prebiotic to optimize rumen development and the efficient use of forage or concentrated diet

The aim of this work was to elucidate the best conditions for preparing rumen microbiome as probiotics and prebiotics by the analysis of fermentation parameters resulting from in vitro incubations (trials 1 and 2). These preparations where then used in an in vivo trial (trial 3) consisting of an inoculation of newborn goat kids with the ruminal microbiota developed in the in vitro experiment. This study used a 2×3×2×2 factorial design to evaluate the effects of two diets (forage and concentrate), three buffers (6.80, 6.25 y 5.75), two sample times (0 vs. 3h) and two ruminal fractions (liquid vs. whole content) of the ruminal content. Eight Murciano-Granadina goats were used as a donor of the ruminal content; each four animals were assigned to one group: FOR received 100% forage (based on 50% alfalfa and 50% oat hay) and CON fed with concentrate and forage (80:20) with the same forage composition. In the first trial, both diet (FOR vs. CON) and buffer were studied; the result showed that independently of the diet, the buffer which generates higher pH promotes higher fermentation activity in terms of VFAs (P equal than 0.001), ammonia (P equal than 0.005), fermentable organic matter (P equal than 0.006) and gas production (P less than 0.001). In the second trial, it was observed that the type of diet exerts a very significant effect on ruminal fermentation in vitro. Compared to the FOR diet, CON promoted greater ruminal fermentation with ruminal contents collected at 3h post-feeding than at 0h. The type of ruminal fraction considered did not show significant differences in relation to the fermentation pattern, gas production and concentration of ruminal microorganisms. Only a lower concentration of anaerobic fungi (P equal than 0.002) was detected in the liquid fraction as a result of the tropism of these microorganisms towards the solid fraction. For the in vivo experiment, seventy four goat kids were randomly distributed into 4 identical groups with 16 and 4 animals (4x4) per group and experimental group respectively: CTL (control group without any inoculation), PRE (group inoculated with ruminal liquor autoclaved), LRC (probiotic group inoculated with ruminal liquor of animals fed concentrate diet) and LRF (probiotic group inoculated with ruminal liquor of animals fed forage diet). Experimental groups had similar average birth weight and the same number of males and females. Newborn goats were daily inoculated with fresh rumen fluid obtained from the same donors used in in vitro experiment during the first 12 weeks of life. The feed intake (milk, concentrate and forage), body weight and rumen fermentation were studied during the same inoculation period. Results of this in vivo trial showed that the inoculation no had an effect on milk or concentrate intakes, however, it had significant effect (P less than 0.05) on forage intake in the weeks 5, 6, 8, 10, 11 and 12 of life with higher values for LRC group (the accumulated intake was 1.2 plus minus 0.31 kg Dry Matter). In addition, the inoculation no affected the body weight of animals, but increased the VFA production during at 5 weeks of age and modified the fermentation pattern at 2 weeks pot-weaning (greater butyrate production). Thus, our results show that using rumen fluid as probiotic can accelerate the rumen physiological and microbiological development and could help to perform an early weaning and enhance the microbial fermentation post-weaning.