Effects of Stocking Density on Growth Performance of Ducks under Climate Change-Related Heat Sango Park College of Animal Life Science, Kangwon National University Chuncheon, Gangwondo-200 701, Republic of Korea *Corresponding author: bspark@kangwon.ac.kr
Online published on 13 April, 2022. Abstract This study was carried out to investigate the effects of high stocking density on growth performance, villus and liver cell morphology, cecum bacteria and heat shock proteins (HSPs) gene expression in meat duck (Cherry valley, Anas platyrhynchos) reared under heat stress (HS). A total of 180 meat ducks were randomly assigned to control group (CON, 3 birds/m2, normal heat environmental condition) and HS groups: low stocking density (LSD, 3 birds/m2), or high stocking density (HSD, 6 birds/m2). The birds were divided into three groups with three replicated pens (20 ducks per pen) per group, and raised for 42 d. The HS was achieved by exposing the birds, during the finishing period (from d 22 to d 42), to an ambient temperature of 34±2°C and a relative humidity of 70% for 5 h (11:00 to 16:00) per day. Body weight and feed intake of HSD group were lower than those of CON and LSD groups. However, FCR was higher in the HSD group. Duodenal villus length, crypt depth, and morphology of liver tissues in the HSD group were decreased or collapsed compared to those of CON and LSD groups, although they were similar between CON and LSD groups. The number of Lactobacillus was higher in CON and LSD groups whereas numbers of E. coli, total aerobic bacteria, and coliform bacteria were higher in the HSD group than in CON and LSD groups. Hsp90-α was deceased in the HSD group than in CON and LSD groups. Hsp70, Hsp60, Hsp40, and Hsp10 were higher in the HSD group than in CON and LSD groups, although HSPs-mRNA expression levels were similar between CON and LSD groups. Results show that raising meat ducks by high stocking density (6 birds/m2) under heat stress resulted in decreased productivity due to damage to the duodenal villus and crypt depth, liver cell morphology, cecum bacteria imbalance, and up-regulated HSPs gene expression. Top Keywords Cecum bacteria, Duck, Growth performance, Heat shock proteins, Heat stress, Stocking density, Tissue morphology. Top |