AUTHOR=Wijnen Hendrikus J. , van der Pol Carla W. , van Roovert-Reijrink Inge A. M. , De Smet Joren , Lammers Aart , Kemp Bas , van den Brand Henry , Molenaar Roos 

TITLE=Low Incubation Temperature During Late Incubation and Early Feeding Affect Broiler Resilience to Necrotic Enteritis in Later Life

JOURNAL=Frontiers in Veterinary Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.784869

DOI=10.3389/fvets.2021.784869

ISSN=2297-1769

ABSTRACT=<p>Resilient animals can cope with environmental disturbances in life with minimal loss of function. Resilience can be enhanced by optimizing early-life conditions. In poultry, eggshell temperature (<bold>EST</bold>) during incubation and early feeding are two early-life conditions that are found to alter neonatal chick quality as well as immune response in later life. However, whether these early-life conditions affect disease resilience of chickens at later ages has never been studied yet. Hence, we studied the effects of EST [(37.8°C (<bold>control</bold>) or 36.7°C (<bold>lower</bold>)] during late incubation (≥embryonic days 17–19.5) and feeding strategy after hatch [immediately (<bold>early feeding</bold>) or 51–54 h delayed (<bold>delayed feeding</bold>)] on later-life broiler resilience in a 2 × 2 factorial arrangement. At hatch, 960 broilers of both sexes from a 54-week-old Ross breeder flock were equally divided over 32 pens (eight replicate pens per treatment combination) and grown for 6 weeks. Necrotic enteritis was induced by a single inoculation of <italic>Eimeria</italic> spp. at d 21 and repeated <italic>Clostridium perfringens</italic> inoculation (3×/d) during d 21–25. Mortality and body weight (BW) gain were measured daily during d 21–35 as indicators of resilience. Additionally, disease morbidity was assessed (gut lesions, dysbacteriosis, shedding of oocysts, footpad dermatitis, and natural antibody levels in blood). Results showed a lack of interaction between EST and feeding strategy for the vast majority of the variables. A lower EST resulted in lower BW gain at d 5 and 8 post <italic>Eimeria</italic> inoculation (<italic>P</italic> = 0.02) and more <italic>Eimeria maxima</italic> oocysts in feces at d 8 post <italic>Eimeria</italic> inoculation compared to control EST (<italic>P</italic> &lt; 0.01). Early feeding tended to lower mortality compared to delayed feeding (<italic>P</italic> = 0.06), but BW gain was not affected by feeding strategy. Morbidity characteristics were hardly affected by EST or feeding strategy. In conclusion, a few indications were found that a lower EST during late incubation as well as delayed feeding after hatch may each impair later-life resilience to necrotic enteritis. However, these findings were not manifested consistently in all parameters that were measured, and conclusions are drawn with some restraint.</p>