The Effect of Lactobacillus acidophilus on Alleviating Stress Response and Production Impairment Induced by Escherichia coli Lipopolysaccharide in Laying Hens

Abstract

Endotoxin stress persuaded by the avian pathogenic Escherichia coli threatens egg production and costs the poultry business significantly in lost revenue. This investigation was carried out to determine the beneficial effects of dietary Lactobacillus acidophilus (LA) on laying hens exposed to endotoxic shock induced by intravenously injection of lipopolysaccharides (LPS). A total of one hundred twenty, 40-week-old, laying hens from the Hy-line breed were allocated at random into four groups of 30 hens each. For eight consecutive weeks (40-48 weeks of age), two groups of the layers were given a basal diet as control, while the remaining two groups were given a basal diet enhanced with a 2 g/ kg diet of LA bacteria. At 47 wk of age, layers in one of the control or LA groups received an intravenous injection for 7 consecutive days with 0.5 ml of sterile saline contained LPS at 8 mg per kg of layer body weight, whereas the layers in the other ones of the control or LA groups received intravenous injection of 0.5 ml saline only. The four treatment groups (control, LPS, LPS+LA, and LA groups, respectively) were monitored for their productive performance over the course of the entire experiment (40-48 weeks). At the conclusion of the trial (48 wk of age), stress indicator parameters including body temperature (BT), H/L ratio, plasma malondialdehyde (MDA), and corticosterone (CORT) concentrations were evaluated in the treatment groups (n=10). Additionally, samples of the spleen and duodenum were taken from layers in each group (n=10) to assess heat shock protein 70 (HSP70) density and glutathione peroxidase (GHS-px) activity, respectively. The general linear model procedure with one-way analysis of variance (GLM-ANO-VA) was used to analyze the data. The results showed a significant (P<0.05) increase in the BT, H/L ratio, MDA, and CORT, and over-expression of HSP70 in the hens of LPS group. Also, significant (P<0.05) impairments were perceived in the feed consumption and conversion, and in the egg weight and production rates. In contrast, the elevated stress markers and HSP70 expression in the challenged birds were significantly (P<0.05) alleviated when LA was given to laying hens, and the GSH-px activity was noticeably increased by 13.7% in the LPS+LA compared to the LPS group. Furthermore, LA increased egg production by 8.5 and 3.1 percent points and improved feed efficiency by 6.11 and 4.56% in both LPS-challenged and non-challenged birds, respectively. Therefore, supplementing layer diets with 2 g/kg LA could be successfully applied to improve the productive performance and minimize the endotoxic stress induced by Escherichia coli LPS challenge in laying hens.