Influence of dietary Lactobacillus-based probiotic or essential oil blend on laying performance, blood parameters and humoral immunity of laying hens reared in summer

Abstract

This study was conducted to investigate the effects of dietary supplementation with Lactobacillus-based probiotic (PRO) and/or essential oil blend (EOB) in laying hens reared under heat stress on laying performance and egg quality, on some blood parameters, and on immunity. Laying hens, exposed to high ambient temperatures during the summer, were allocated in 4 experimental treatments for 16 weeks. (192), 52-week-old, Birds were fed a basal diet (control) or the same diet supplemented with PRO (0.5 g/kg) or EOB (36 mg/kg) or PRO+ EOB (with the same dosages). The egg weight were markedly enhanced in eggs from hens treated with EOB, and the dietary supplementation with PRO and EOB alone or combined with each other has significantly increased Haugh unit and albumen height (P<0.05). The intestinal pH was dramatically depressed in PRO and in PRO+EOB supplemented hens, whereas the intestinal viscosity was significantly reduced only in birds treated with both additives (P<0.01). Supplementing PRO and EOB in diet tend to improve (not significantly) antibody responses against Newcastle disease virus (NDV) and infectious bursal disease virus (IBDV). It was concluded from this study that PRO and/or EOB supplementation in laying hens exposed to high temperatures improves egg weight and egg qualities and partly promotes humoral immunity.