Abstract:

This experiment mainly aimed at isolating and identifying lactic acid bacteria from the gut of healthy Hyline brown laying hens, and detected the effect of the isolated lactic acid bacteria on intestinal health of laying hens in early brood period. Bacterial culture, 16S rRNA and Oxford Cup diffusion methods were used to isolate, screen and identify Lactobacillus strains that could producing bacteriocins. The tolerance to high temperature, pH and bile salt was assessed. Two hundred and forty healthy one-day-old Hyline brown laying hens with similar body weight were randomly divided into four groups: control group (C), low dose Lactobacillus salivarius CL09 group (L), medium dose Lactobacillus salivarius CL09 group (M) and high dose Lactobacillus salivarius CL09 group (H). The effects of this strain on growth performance, immune organ index and intestinal health were analyzed. The experiment lasted for 21 days. The results showed that the isolated strain was a bacteriocin-producing Gram-positive bacteria, identified as Lactobacillus salivarius CL09 based on 16S rRNA identification. The cell-free supernatant of Lactobacillus salivarius CL09 demonstrated inhibitory effects on the growth of Escherichia coli, Salmonella, Staphylococcus aureus and Listeria. The resistant temperature of Lactobacillus salivarius CL09 was 60 ℃, and possessed the characteristics of acid and bile salt tolerance. The results of animal testing showed the Lactobacillus salivary CL09 supplementation could improved body weight and immune organ weight, with noticeable decreases in crypt depth of duodenum and jejunum observed in the H group, and significant increase in villus height of duodenum observed in L and M groups. The intestinal villi in the group H showed a wavy trend. Additionally, the mRNA levels of intestinal stem cell marker genes Lgr5 and Bmi1 were significantly increased in the M and H group(P < 0.001), while the mRNA level of mucosal barrier genes Zo-1 and Ocln was significantly increased in the H group(P < 0.01). Lactobacillus salivarius CL09 supplementation also led to the increasing of mRNA levels of Pan's cell marker gene Lyz and goblet cell marker gene Muc (P < 0.01). In summary, Lactobacillus salivary CL09 isolated from the gut of healthy Hyline brown laying hens, has the potential to enhance villi length and crypt depth by promoting differentiation of intestinal stem cells into Paneth and goblet cells, thereby increasing the mucosal surface area in the intestine. Lactobacillus salivary CL09 exhibits favorable characteristics for regulating the intestinal health of chicks in the early brood period, and could be considered as a candidate probiotic strain.

Key words: laying hens, Lactobacillus salivarius, intestinal health, villus height, crypt depth