Isolation Of Lactic Acid Bacteria And Their Effects On Broiler Production Performance

The aims of this work were:(1) to isolate and screen lactic acid bacteria from healthybroiler in Shaanxi in vitro; and (2) to study the effect of selected lactic acid bacteria ongrowth performance of broilers in vivo. It was hoped that the results from these two studieswould lead to development of new lactic acid bacteria as probiotics for poultry production.In the first experiment, lactic acid bacteria were isolated from muscular stomach, crop,duodenum, jejunum, ileum, cecum of broilers raised in Shaanxi. Lactic acid bacteria wereisolated by using a selective medium and confirmed by PCR of16s rRNA. Thereafter, thesestrains were tested for acid-resistance, cholate-resistance and antibacterial activities in vitro.Among90isolated lactic acid bacteria strains,4strains (Pediococcus acidilactici C252,Enterococcus faecalis M23, Lactobacillus salivarius ZM01and Lactobacillus plantarum J113)were selected for a further in vivo study due to their high acid-resistance, cholate-resistanceand antibacterial activities in vitro.In the second experiment, five hundred seventy-six1-d-old broilers were randomlyallocated in6experimental treatments on the basis of body weight (BW) for6-wk trial. Thedietary treatments included the basal diet (control), and the basal diets supplemented with anantibiotic (50mg of aureomycin/kg of diet), Pediococcus acidilactici C252(109cfu/kg of diet),Enterococcus faecalis M23(109cfu/kg of diet), Lactobacillus salivarius ZM01(109cfu/kg ofdiet) or Lactobacillus plantarum J113(109cfu/kg of diet). Each treatment had6replicates with16broilers. The four LAB strains were fermented and dry-freezed into powder before addingto the feed. The effect of dietary supplementation of lactic acid bacteria was investigated ongrowth performance, intestinal histomorphology and digestive enzyme activities. There wereno significant differences in growth performance of broilers during1to21d among differentdietary treatments (P>0.05). However, during22to42d and1-42d, average daily gain(ADG) were improved in broilers fed diets supplemented with Enterococcus faecalis M23,Lactobacillus salivarius ZM01or Lactobacillus plantarum J113relative to the control(P<0.05). There was no difference between supplemented groups and the antibiotic group(P>0.05); In comparison with the control and the antibiotic groups, Enterococcus faecalisM23, Lactobacillus salivarius ZM01supplementation improved feed conversion rate (FCR) (P<0.05). The body weight (BW) of42-d-old broilers was significant higher in theEnterococcus faecalis M23, Lactobacillus salivarius ZM01and Lactobacillus plantarum J113groups compared with the control group(P<0.05), and was similar to the antibiotic group.Moreover, broilers fed Enterococcus faecalis M23had higher amylase activities on days of14,28and42compared with the control group (P<0.05), while Lactobacillus salivarius ZM01showed an improved lipase activity at day of28compared with the control group (P<0.05).Furthermore, dietary treatments influenced the histomorphological measurements of smallintestinal villi. At day of14, the duodenal crypt depth were decreased by dietarysupplemented with antibiotic, Enterococcus faecalis M23, Lactobacillus salivarius ZM01orLactobacillus plantarum J113in comparision with the control group (P<0.05), Enterococcusfaecalis M23supplemented group was even lower than the antibiotic group (P<0.05). Theaddition of Pediococcus acidilactici C252, Enterococcus faecalis M23or Lactobacillusplantarum J113increased the villus height:crypt depth ratio and villus height induodenum(P<0.05). At day of28, the antibiotic, Enterococcus faecalis M23, Lactobacillussalivarius ZM01increased villus height (P<0.05), while the duodenal crypt depth and villusheight: crypt depth ratio remained unaffected in all lactic acid bacteria treated groups(P>0.05). At day of42, addition of Enterococcus faecalis M23, Lactobacillus plantarum J113,Lactobacillus salivarius ZM01or antibiotic increased (P <0.05) the villus height: crypt depthratio and villus height in duodenum. However, the duodenal crypt depth remained unaffected(P>0.05).Our results showed that adding lactic acid bacteria in broilers diet could improvedigestion and absorption function, and enhance growth performance, similar to the antibiotictreatment.