Effects Of Oligosaccharides On Gut Microorganisms From Broilers In Vitro And Growth Performance Of Broilers

The effects of oligosaccharides on the growth of different lactic acid bacteria (LAB)were investigated to select those that could stimulate the growth of LAB. The selected twooligosaccharides were further used to investigate the dose effects on LAB and mixedmicroflora from ileal and caecal digesta by in vitro fermentation. Their effects on thegrowth performance of broilers and their intestinal microbes were also investigated. Thispaper includes four sections:In the first section, the effects of five different oligosaccharides on the fermentation bymixed LAB from digesta and three single LAB strains from intestinal mucous wereinvestigated. The results showed that mixed and. single LAB strain grew better in the basalmedium containing GOS or IMO, particularly in the medium containing GOS. The LABstrains grew worse in the medium containing FOS or Inulin.In the second section, IMO and GOS at levels of 0.0%,0.4%,0.8%,1.0%,1.2% and1.6%(w/v) were used to investigate their dose effects. The results showed that the growth ofthe selected LAB increased significantly with the increased level of two substrates (P＜0.05).The LAB grew well in the medium containing 1.2%GOS and the medium containing 1.6%IMO.In the third section, the effects of GOS and IMO at levels of 0.5%, 1.0% and 1.5%(w/v) on the fermentation of intestinal microbes were investigated. The fresh digesta fromileum and caecum were used as inoculums with anaerobic culture fermentation. The resultsshowed that IMO and GOS were utilized rapidly by both ileal and caecal microbes. In themedium inoculated with ileal digesta, the pH value of the medium decreasedsignificantly(P＜0.05), the lactic acid concentration increased significantly (P＜0.05) as GOSor IMO level increased. In the medium inoculated with caecal digesta, the pH value of themedium decreased significantly (P＜0.05) as GOS or IMO level increased. The lactic acidconcentration was higher at 1.5% level than that at 0.5%, 1.0% level(P＜0.01). VFA in themedium inoculated with caecal digesta were analyzed. Acetate increased significantly(P＜0.05), while propionate, butyrate and total VFA increased and then decreased as GOS orIMO concentration increased. Under the condition of same level of different substrates,when inoculated with ileal digesta, the pH value decreased, and the concentration of lactic acid increased in IMO and GOS groups compared with that glucose as substrate; Wheninoculated with caecal digesta, lower pH value, higher acetate and higher total VFA withIMO and GOS were found compared to those with glucose as substrate. It was suggestedthat IMO and GOS at 1.0% (w/v) concentration condition could promote the fermentationof the intestine microbes.In the fourth section, the effects of IMO and GOS on the growth performance ofbroilers and their intestinal microbial ecosystem were investigated. A total of 720 AAbroilers at the age of one day were randomly divided into eight groups. ControlⅠandⅡwere fed with the basal diets without and with antibiotics. The other six groups were fedwith the addition of 0.1%,0.2%,0.4% IMO and 0.2%,0.4%,0.6%GOS in the basal dietswithout antibiotics, respectively. The results showed that during the age from 1 to 20, thebroilers' average weight and the average daily weight gain significantly increased in thegroup with addition of 0.2%IMO, and the ratio of feed to weight gain was reduced (P＜0.05).During the age from 21 to 42, the growth performance of broilers in the group with additionof 0.4%IMO appeared to be better compared with that in controlⅠand the groups withaddition of 0.1%,0.2%IMO(P＞0.05). Addition of GOS in the diets had no effects on theanimal performance during the whole 42 days. IMO and GOS increased the viable countsof Lactobacillus, and decreased the viable counts of E.coli during the fist 20days.