Effects Of Moderate Temperature, Humidity And Air Velocity On Immune Functions In Broiler Chickens

Moderate environment is widespread in the poultry production. The effects of moderate temperature, humidity and air velocity on immune functions in broiler chickens were studied in this paper in order to provide theoretical basis of breeding subtly and comfortably. There are three parts. The main contents are summarized as follows:1. Effects of constant moderate temperatures on immune functions in broiler chickens.144 22-day-old Arbor Acres(AA) broilers were assigned randomly to three environment chambers, each chamber contained six cages with eight birds per cage(with four males and four females), and each cage as a replicate. The trial began after 7 days pre-test period. Then the temperatures of each environmental chamber were gradually regulated to 21 ℃, 26 ℃ and 31 ℃, respectively, while maintaining the relative humidity at 60%. The trial period lasted for 14 days. The results showed as follows: 1) Comparing with 21 ℃ treatments, 31 ℃ treatment significantly reduced the spleen index on day 7(P<0.05), significantly reduced the bursa index on day 7 and 14(P<0.05), significantly reduced total protein, globulin, lysozyme and IL-6 in serum on day 1(P<0.05), significantly increased albumin in serum on day 1 and 7(P<0.05), significantly increased IL-1β during all period(P<0.05), significantly reduced villus height and increased crypt depth of jejunum and ileum on day 14(P<0.05), significantly reduced secretory IgA(sIgA) of duodenum and ileum on day 1 and 7(P<0.05); 2) Comparing with 21 ℃treatments, 26 ℃ treatment had no significant effect on the thymus index of broilers(P>0.05), significantly increased total protein on day 1 and 14(P<0.05), significantly increased albumin on day 1 and 7(P<0.05), significantly increased globulin on day 14(P<0.05), significantly reduced lysozyme on day 1(P<0.05), significantly increased IL-1β on day 1(P<0.05), significantly reduced villus height of jejunum and ileum on day 14(P<0.05), and significantly increased crypt depth of ileum on day 14(P<0.05), significantly reduced sIgA of duodenum on day 7(P<0.05);in conclusion, compared with 21 ℃ group, the constant moderate temperature(26 ℃and 31 ℃) could affect the development of immune organs, cytokines, damage intestinal morphology and reduced intestinal immune function.2. Effect of relative humidity at intermittent moderate temperatures on immune functions in broiler chickens.360 22-day-old AA broilers were assigned randomly to six environment chambers, each chamber contained six cages with ten birds per cage(with five males and five females), and each cage as a replicate. The trial began after 7 days pre-test period and set each chamber to required condition. The trial period lasted for 14 days. 2×3 two factorial design was used. Temperature had two levels: 26 ℃and 31 ℃; relative humidity had three levels: 30%, 60% and 85%. All treatments were intermittent, which set during 10:00am to 16:00pm every day. Other time the treatment maintained at 21 ℃+60% RH. The results showed as follows: 1) Comparing with 30% RH and 60% RH treatments, 85% RH significantly reduced villus height of ileum 4 and sIgA of jejunum on day 1(P<0.05), significantly increased IL-6 on day 14(P<0.05); comparing with 60% RH treatments, 30% RH and 85% RH significantly reduced sIgA of duodenum on day 1(P<0.05); comparing with 26 ℃ treatments, 31 ℃ treatment significantly reduced globulin on day 7 and lysozyme on day 14(P<0.05), significantly increased IL-6 on day 14(P<0.05); RH, intermittent moderate temperatures and their interaction reduced immune function, 31 ℃+85% RH affected deeply.3. Effect of air velocity at acute moderate temperatures on physiological, endocrine and immune indices in broiler chickens.150 42-day-old AA broilers were assigned randomly to fifteen s, each treatment contained ten male birds, and each bird as a replicate. Before each treatment ten birds were selected from reserved environment chamber. Each treatment contained 6 h adaptive period and 6 h test period. Adaptive period and reserved chamber both were 21 ℃+60% RH. Environment chamber set temperature and humidity, air velocity was controlled by “tunnel ventilation chamber”. 3×5 two factorial design was used. Temperature had three levels: 26 ℃, 29 ℃ and 31 ℃; air velocity had five levels: 0 m/s, 0.5 m/s, 1.0 m/s, 1.5 m/s and 2.0 m/s. The results showed as follows: 1) interaction significantly affected Tc、Fr、Ts、T3 and CORT(P<0.05); under 26 ℃ condition, 1.5 m/s significantly reduced Tc(P<0.05), 2.0 m/s significantly reduced Fr(P<0.05), 1.0 m/s significantly reduced Tes、Tcs and Tss(P<0.05); under 29 ℃ condition, 1.0 m/s significantly reduced Tc、Tes、Tcs and Tss(P<0.05); under 32 ℃ condition, 1.0 m/s significantly reduced Tc、and Fr(P<0.05), 0.5 m/s significantly reduced Tes、Tcs and Tss(P<0.05); 32 ℃+0 m/s and 32 ℃+0.5 m/s increased Tc,Ts, Fr, and reduced T3 deeply; 2) under acute moderate temperatures, low air velocity exacerbated heat load, air velocity had no effect on immune indices, the best air velocity was 1.5 m/s; 3) air velocity at acute moderate temperatures affects physiological, endocrine and immune indices in broiler chickens.In conlusion, 1) constant moderate temperature(26 ℃and 31 ℃) could affect the development of immune organs, cytokines, damage intestinal morphology and reduced intestinal immune function; 2) RH, intermittent moderate temperatures and their interaction reduced immune function, 31 ℃+85% RH affected deeply; 3) air velocity at acute moderate temperatures affectes physiological, endocrine and immune indices in broiler chickens, 32 ℃+0 m/s and 32 ℃+0.5 m/s increased Tc,Ts, Fr, and reduced T3 deeply, under acute moderate temperatures, low air velocity exacerbated heat load, air velocity had no effect on immune indices, the best air velocity was 1.5 m/s.