Newcastle viral disease causation web correlations with laying hen productivity

Abstract

Environmental conditions profoundly impact the health, welfare, and productivity of laying hens in commercial poultry farming. We investigated the association between microclimate variations, production indices, and histopathological responses to accidental Newcastle disease virus (NDV) infection within a controlled closed-house system. The study was conducted over seven months in a laying hen facility in Cairo, Egypt. Microclimate measurements included temperature, relative humidity (RH%), air velocity (AV), and the temperature humidity index (THI) that were obtained from specific locations on the front and back sides of the facility. Productivity indices, including the egg production percentage (EPP), egg weight (EW), average daily feed intake, and feed conversion ratio, were assessed monthly. During an NDV outbreak, humoral immune responses, gross pathology, and histopathological changes were evaluated. The results demonstrated significant (p < 0.05) variations in EPP and EW between the front and back sides except in April and May. AV had a significant (p = 0.006) positive effect (Beta = 0.346) on EW on the front side. On the back side, AV had a significant (p = 0.001) positive effect (Beta = 0.474) on EW, while it negatively influenced (p = 0.027) EPP (Beta = - 0.281). However, temperature, RH%, and THI had no impact and could not serve as predictors for EPP or EW on either farm side. The humoral immune response to NDV was consistent across microclimates, highlighting the resilience of hens. Histopathological examination revealed characteristic NDV-associated lesions, with no significant differences between the microclimates. This study underscores the significance of optimizing microclimate conditions to enhance laying performance by providing tailored environmental management strategies based on seasonal variations, ensuring consistent airflow, particularly near cooling pads and exhaust fans, and reinforcing the importance of biosecurity measures under field challenges with continuous monitoring and adjustment.

Keywords: Climate change; Egg production; Egg weight; Outbreaks; Poultry welfare; Sustainability.

Figure 1

A schematic illustration of the chicken house’s construction.

Figure 2

Maximum and minimum values of egg production % and egg weight during the study 7 months in the farm indoor front, and indoor back sides.

Figure 3

Maximum and minimum values of temperature (T°C) and RH% during the study 7 months in the farm outdoor climate, indoor front, and indoor back.

Figure 4

Maximum and minimum values of air velocity (m/s) and temperature-humidity index (THI) during the study 7 months in the farm outdoor climate, indoor front, and indoor back.

Figure 5

Standardized Coefficient (Beta) of indoor climatic predictors for hen-day egg production % and egg weight in the front and back sides of the layer farm.

Figure 6

Gross pathological changes of the naturally NDV-infected laying hens. Lesions in the trachea, lung, and proventriculus were at the front (A–C) and back (a–c) side of the farm: (A) Congested tracheal mucosa (arrow), (B) Severe congestion and hyperemia of the lung tissue (arrow), (C) Hemorrhages (arrow) at the tip of the proventricular gland, (a) Congested tracheal mucosa (arrow), (b) Congestion and hyperemia of the lung tissue (arrow), (c) Hemorrhages (arrow) at the tip of the proventricular gland.

Figure 7

Histopathological changes in the trachea of the naturally NDV-infected laying hens at the front and backside of the farm. Front side: (A) Thickening of the tracheal mucosa with lymphoplasmacytic infiltration (black arrowhead); (B,C) mucosal ulceration with congested blood vessels, hyperplasia of the mucosal gland (red arrowhead), and lymphoplasmacytic infiltration (black arrowhead) (H&E). Back side: (a) severe desquamation of the tracheal epithelium with lymphoplasmacytic infiltration (black arrowhead); (b,c) Mucosal sloughing (red arrow), lamina propria and submucosa heavily infiltrated with inflammatory cells (black arrowhead) with extensive edema (asterisk) and congested blood vessels (black arrow) in lamina propria and submucosa (H&E).

Figure 8

Histopathological changes in the lung of the naturally NDV-infected laying hens at the front and backside of the farm. Front side: (D,E) Parabronchus lumen filled with fibrin (asterisk), widening of the interstitial tissue with fibrin and inflammatory cells (red arrowhead), and congested blood vessels (black arrowhead) (H&E). Back side:(d) Diffuse fibrin exudation in the lumen of parabronchus (asterisk) and congested blood vessels (black arrowhead); (e) Thickening of the bronchiolar wall with inflammatory cells (red arrowhead) mainly heterophiles and lymphocytes extending to interstitial tissue (H&E).

Figure 9

Histopathological changes in the proventriculus of the naturally NDV-infected laying hens at the front and back side of the farm. The front side (F,G) and backside (f,g) showed degeneration and necrosis of the acinar glands (red arrowhead), infiltration of the lumen with necrotic debris (asterisk) of mononuclear inflammatory cells and heterophile, and congested blood vessels (black arrowhead) (H&E).