Snyder Ashlyn M, Riley Sean P, Robison Cara I, Karcher Darrin M, Wickware Carmen L, Johnson Timothy A, Weimer Shawna L
Department of Animal and Avian Sciences, University of Maryland, College Park, MD, United States.
Department of Veterinary Medicine, University of Maryland-College Park, College Park, MD, United States.
Front Physiol. 2022 May 2;13:890848. doi: 10.3389/fphys.2022.890848. eCollection 2022.
Fast growth rate in broiler chickens comes with welfare concerns and the contribution of growth rate to pathogen resistance and sickness behavior is relatively unknown. The objective of this study was to evaluate physiological and behavioral responses of conventional (CONV) and slow-growing (SG) male broilers challenged with Typhimurium. CONV ( = 156) and SG ( = 156) chicks were raised in a pen with wood litter shavings until day 7 of age, when birds were transferred to 24 isolators ( = 11 chicks/isolator). On day 14 of age, half of the birds ( = 12 isolators) were challenged with Typhimurium (ST) and the other half ( = 12 isolators) received a control (C). On days 7, 13, 17, 21, and 24, body weight was recorded, and blood, jejunum and ileum sections were collected from 2 birds/isolator ( = 48 birds/sampling) to measure plasma IgA and IgG and intestinal histomorphology, respectively. On days 12, 16, 21, and 23, video was recorded to evaluate bird postures (sitting, standing, or locomoting) and behaviors (eating, drinking, preening, stretching, sham foraging, allopreening, and aggression). CONV birds were 70 g heavier ( 0.03) on day 21 and 140 g heavier ( = 0.007) on day 24 than SG. On day 7, CONV jejunum villus height and crypt depth were 22 and 7 μm greater ( ≤ 0.001), respectively, than SG. On day 24, ST ileum villus height was 95 μm shorter ( = 0.009) than C. IgA increased after day 17 for all birds and at day 21, CONV IgA was greater ( = 0.01) than SG. Although SG IgG was 344 μg/ml greater ( = 0.05) than CONV on day 7, CONV IgG increased with age ( < 0.0001) to greater ( ≤ 0.03) concentrations than SG on day 21 and day 24 by 689 μg/ml and 1,474 μg/ml, respectively, while SG IgG remained at similar concentrations after day 13. Generally, a greater proportion of birds sham foraged as they aged ( < 0.0001). A greater proportion of CONV tended to sit ( = 0.09) and fewer locomoted ( 0.0001) than SG as they aged. The results illustrate conventional and slow-growing broilers differ in their behavior, immunity, and response to .
肉鸡的快速生长伴随着福利问题，而生长速率对病原体抵抗力和疾病行为的影响相对未知。本研究的目的是评估感染鼠伤寒沙门氏菌的常规（CONV）和慢速生长（SG）雄性肉鸡的生理和行为反应。CONV（n = 156）和SG（n = 156）雏鸡在铺有木屑的围栏中饲养至7日龄，之后将鸡转移到24个隔离器中（每个隔离器11只鸡）。在14日龄时，一半的鸡（n = 12个隔离器）感染鼠伤寒沙门氏菌（ST），另一半（n = 12个隔离器）作为对照（C）。在第7、13、17、21和24天，记录体重，并从每个隔离器中选取2只鸡（每次采样共48只鸡）采集血液、空肠和回肠组织，分别测量血浆IgA和IgG以及肠道组织形态学。在第12、16、21和23天，录制视频以评估鸡的姿势（坐着、站立或移动）和行为（进食、饮水、梳理羽毛、伸展、假觅食、相互梳理羽毛和攻击行为）。在21日龄时，CONV鸡比SG鸡重70克（P = 0.03），在24日龄时重140克（P = 0.007）。在7日龄时，CONV空肠绒毛高度和隐窝深度分别比SG鸡大22微米和7微米（P≤0.001）。在24日龄时，感染ST的鸡回肠绒毛高度比对照鸡短95微米（P = 0.009）。所有鸡在17日龄后IgA增加，在21日龄时，CONV鸡的IgA高于SG鸡（P = 0.01）。虽然在7日龄时SG鸡的IgG比CONV鸡高344微克/毫升（P = 0.05），但CONV鸡的IgG随年龄增长（P < 0.0001），在21日龄和24日龄时分别比SG鸡高689微克/毫升和1474微克/毫升（P≤0.03），而SG鸡的IgG在13日龄后保持在相似浓度。一般来说，随着鸡龄增长，假觅食的鸡比例增加（P < 0.0001）。随着鸡龄增长，CONV鸡倾向于坐着的比例更高（P = 0.09），移动的比例更低（P < 0.0001）。结果表明，常规肉鸡和慢速生长肉鸡在行为、免疫力和对[病原体]的反应方面存在差异。
