Effect of two brooding systems and four stocking densities on immune response and stress indicators of broiler chicks during the brooding period

Abstract

This experiment investigated the effects of the brooding system (BS) and stocking density (SD) on the immune response of 1-14-day-old broiler chicks. A 3672 one-day-old Cobb 500 chicks were raised in two BSs (conventional floor brooding system (CFBS) and the newly developed multi-tier closed brooding system (NDBS)) at four different SDs (30, 60, 90, and 120 chicks/m2), resulting in a 2 × 4 factorial arrangement. Immunity data on lymphoid organ weights, maternal antibody titres to IBV, IBDV, and NDV, and stress indicators were collected on days 6 and 12. The results showed that CFBS and NDBS had similar effects on the relative development of chick lymphoid organs (Bursa, spleen, and thymus), the durability of the maternal humoral immune response against IBDV, and the maintenance of normal levels of stress indicators. Birds in CFBS outperformed NDBS in terms of the durability of maternal immunity to IBV and NDV. Birds in NDBS had a higher liver weight percentage than CFBS. Maternal immunity, lymphoid organ weights %, glucose and cholesterol concentrations were not altered by SD. In contrast to relative weights, differences in absolute lymphoid weights (g) were attributed to differences in live weights. An increase in SD per area unit resulted in an increase in heterophils and a decrease in lymphocyte percentage resulted in an increase in the ratio of heterophils to lymphocytes(H:L). In conclusion, birds in the higher SD had lower live weights and higher H:L ratios. Smarter brooding systems are needed to usher in a new era for the poultry industry.Highlights The brooding system and/or stocking density accounted for the stress factors of the birds. Both brooding systems increased the relative development of chick lymphoid organs and the durability of the maternal humoral immune response to IBDV. Smarter brooding systems are needed to apply the critical control point standard and usher in a new era for the poultry industry. As stocking density per unit area increased, live and liver weights decreased, and the lymphocyte ratio increased.

Keywords

• broilers
• brooding system
• immune status
• stress indicators
• stocking density