Stress Response In Broilers Research Articles

Early heat exposure effect on the heat shock proteins in broilers under acute heat stress

The effects of early heat conditioning on the acute heat stress response in broilers were investigated via the growth performance, dopamine, serotonin, and corticosterone and the expression of heat shock proteins (HSP) and heat shock factors. One-day-old chicks (n = 144) were divided into 3 groups in a 35-d experiment (48 chicks per each group). Group 1 (C) was treated with an optimum temperature, group 2 (CH) was treated with 40°C ± 1°C on day 35 (5 h), and group 3 (HH) was treated with 40°C ± 1°C on day 5 (24 h) and day 35 (5 h). On day 7, the body weight gain was lower (P < 0.05) in HH than in C and CH. On day 35, the heat-treated groups (CH and HH) had lower weight gains than the C group (P < 0.05), whereas the feed conversion ratio was lower in HH (P < 0.05). Serum corticosterone was higher in CH than in C, but HH and C did not differ (P < 0.05). Liver HSP70 protein expression was higher in CH than HH and C (P < 0.05), which did not differ, and HSP40 protein expression was higher in CH than C (P < 0.05). These results suggest that early heat conditioning may reduce acute heat stress on broiler.

Effects of supplementing yeast fermentate in the feed or drinking water on stress susceptibility, plasma chemistry, cytokine levels, antioxidant status, and stress- and immune-related gene expression of broiler chickens

This study aimed to elucidate the mechanism by which adding Saccharomyces cerevisiae–derived yeast fermentate to the feed (XPC) or drinking water reduces stress in poultry. Day-old male Cobb 500 broiler chicks were assigned to 1 of 3 treatments: stressed control (CS), stressed + XPC (1.25 kg/metric ton feed, day 0–43; XPC), or stressed + AviCare (160 mL/100 L drinking water, day 0–43; AVI). All birds were spray-vaccinated for coccidiosis (day 0), raised on reused litter, spray-vaccinated for Newcastle/Bronchitis (day 18), and exposed to heat stress (32°C–34°C) and feed/water withdrawal for 12 h (day 18). Blood samples were collected to assess plasma corticosterone (CORT) and heterophil/lymphocyte (H/L) ratio (60 birds/treatment; day 40); plasma biochemistry and growth hormone (12 birds/treatment; day 38); and serum serotonin and plasma prolactin, thyroid hormones, antioxidant capacity, and selected cytokines (12 birds/treatment; day 39). Composite asymmetry scores were obtained from 60 birds/treatment on day 41. Organs were collected from 20 birds/treatment on day 43 to measure gene expression of CYP1A2 and melanocortin 2 receptor (MC2R) in the adrenal glands and IL10 and AvBD1 in the spleen. Serotonin was lower in CS than XPC (P = 0.049), whereas AVI was intermediate. Plasma interleukin (IL)-1β was higher in AVI than CS (P = 0.009) and XPC (P = 0.009). The CS treatment had higher CORT than AVI (P = 0.013) and XPC (P = 0.037) and higher H/L ratios than AVI (P = 0.026) and XPC (P = 0.034). Expression of CYP1A2, MC2R, and IL10 was lower (P < 0.05) in XPC and AVI compared with CS. Furthermore, IL10 expression was lower in XPC than AVI (P < 0.05). Adding yeast fermentate to the feed or drinking water reduced measures of stress and MC2R gene expression in birds exposed to acute and rearing stressors. However, differences in IL10 gene expression and circulating serotonin and IL-1β suggest that supplementing yeast fermentate in the feed is slightly more effective than supplementation via the drinking water in mitigating the physiological effects associated with the stress response in broilers.

Sulfate and hydroxychloride trace minerals in poultry diets – comparative effects on egg production and quality in laying hens, and growth performance and oxidative stress response in broilers

ABSTRACTTwo experiments investigated the effect of sulfate and hydroxychloride trace minerals (TM), Zn, Cu, and Mn, in laying hens and broiler chickens. In Expt. 1, Lohmann Brown pullets (total of 1,344) at 21 wk of age were used for a 24-wk experiment. Each of the two treatments had 32 replicates with 21 hens per replicate. At 45 wk of age, three eggs per cage were randomly selected and used for internal quality assessment. In Expt. 2, Ross 308 broilers (total of 1,080) were allocated to two treatments. Each treatment had 30 replicates with 15 chicks per replicate. On day 28, after weighing, three birds were randomly selected from 15 randomly selected pens per treatment. The birds were euthanized and blood was collected for analysis for uric acid, C-reactive protein and methylmalonic acid. Samples were also taken from pectoralis muscle of each chicken and analyzed for mRNA expression of protein synthesis or hydrolysis genes. On day 35, 7 birds per pen were used for carcass evaluation. In Expt. 1, egg weight was greater (P < 0.01) in birds receiving sulfate TM from week 16 (of experiment) onwards whereas the percentage of cracked eggs was lower (P < 0.01) in hens receiving hydroxychloride TM. Percentage hen-day production tended to be greater (P < 0.10) in hens receiving hydroxychloride TM in weeks 4 to 8 only. In Expt. 2, birds receiving hydroxychloride TM had greater (P < 0.05) weight gain and tended to have greater (P < 0.10) feed intake on day 35. Expression of the gene, PSMA1, was lower (P < 0.05) whereas plasma level of uric acid and methyl malonic acid tended to be lower (P < 0.10) in birds receiving hydroxychloride TM. It was concluded that hydroxychloride TM reduced egg loss in hens at peak production and that improved growth performance response in broilers can be partly explained by reduction in proteolytic activities in the pectoralis muscle and greater resilience to oxidative stress.

Effect of a combination of green and blue monochromatic light on broiler immune response

Our previous study suggested that green light or blue light would enhance the broiler immune response; this study was conducted to evaluate whether a combination of green and blue monochromatic light would result in improved immune response. A total of 192 Arbor Acre male broilers were exposed to white light, red light, green light, and blue light from 0 to 26days. From 27 to 49days, half of the broilers in green light and blue light were switched to blue light (G–B) and green light (B–G), respectively. The levels of anti-Newcastle disease virus (NDV) and anti-bovine serum albumin (BSA) IgG in G–B group were elevated by 11.9–40.3% and 17.4–48.7%, respectively, compared to single monochromatic lights (P<0.05). Moreover, the proliferation of peripheral blood T and B lymphocytes and the IL-2 concentration in the G–B groups increased by 10.4–36.2%, 10.0–50.0% and 24.7–60.3% (P<0.05), respectively, compared with the single monochromatic light groups. However, the serum TNF-α concentration in the G–B group was reduced by 3.64–40.5% compared to other groups, and no significant difference was found between the G–B and B–G groups in any type of detection index at the end of the experiment. These results suggested that the combination of G–B and B–G monochromatic light could effectively enhance the antibody titer, the proliferation index of lymphocytes and alleviate the stress response in broilers. Therefore, the combination of green and blue monochromatic light can improve the immune function of broilers.

Physiological stress responses in broilers as affected by drinking water supplements or dietary corn particle size

The detrimental effects of physiological stress on broilers are well documented. However, little research exists to delineate the effects of different nutritional regimens on the stress response in broilers. Hence, an experiment was conducted to examine the effects of sucrose and supplemental water electrolytes on Ross 308 male broilers during corticosterone-induced stress, as well as the particle grind size during poststress recovery. Feeding broilers supplemental water electrolytes during corticosterone-induced stress resulted in improved live performance. Feeding water sucrose to stressed broilers did not result in live performance improvements during the stress period. However, broilers fed water-sucrose or water-electrolyte treatments during the stress period had improved feed conversion during stress recovery. Feeding broilers a diet with increased particle size during stress recovery had no effect on live performance. Carcass measurements were not affected by any treatment. Water-electrolyte or water-sucrose supplements appear to have some potential as stress amelioration agents and thus should be researched more thoroughly.

Effects of Monochromatic Light on Immune Response of Broilers

A total of 260 one-day-old Arbor Acres male broilers were exposed to red light (RL), green light (GL), blue light (BL), and white light (WL), respectively, by using a light-emitting diode system for 7 wk. There were 5 replicate pens for each light treatment and 13 birds per pen. The effects of monochromatic light on the immune response were studied. The results indicated that proliferation of peripheral blood T lymphocytes in the GL group was significantly increased (by 80.8 and 54.8%) compared with those in the RL and BL groups, respectively, at 21 d of age (P < 0.05). At 49 d of age, however, the proliferation response was significantly increased in the BL group compared with the RL group (26.9%, P< 0.05). Moreover, the GL group showed a significant elevation in the serum anti-Newcastle disease virus level as compared with that of the RL group at 28 d of age (32.9%, P < 0.05). In contrast, no significant difference in serum anti-Newcastle disease virus level was observed among the BL, RL, and WL groups at this age (P > 0.05). By 49 d of age, the antibody titer was higher in the BL group than in the RL group (62.8%, P < 0.05). However, no significant difference in antibody titer was seen among the BL, GL, and WL groups at this age. Interestingly, the BL group showed a 44.0% reduction in the level of serum interleukin-1β as compared with that in the RL group at 49 d of age (P < 0.05). These results suggest that GL and BL enhance the immune response better than RL, and that BL may play a role in alleviating the stress response in broilers.

Incubation and rearing temperature effects on Hsp70 levels and heat stress response in broilers

Incubation temperature (IT) was changed to evaluate if 6-wk-old birds become more tolerant to heat stress. After 13 d of incubation, 470 eggs were submitted to low (36.8°C), normal (37.8°C) and high (38.8°C) temperatures. At day 7 post-hatching, 144 birds were allocated to three rearing temperatures (48 birds/treatment): control/thermoneutral (35–24°C), high (33–30°C) or low (27–18°C) according to the age of the birds. Hsp70 levels in tissues of birds (1 d and 42 d), stress response (42 d) and performance were evaluated. High IT decreased brain (P &lt; 0.01) and liver (P &lt; 0.01) Hsp70 levels, whereas low IT decreased brain (P &lt; 0.01) but increased heart (P &lt; 0.01) Hsp70 levels in 1-d old chicks. Birds incubated at a low temperature had higher (P &lt; 0.05) feed intake (1-42 d). High rearing temperature decreased feed intake (P &lt;0.01) and liveweight (P &lt;0.01). Colonic temperature was lower in birds incubated at a low temperature (P &lt; 0.05) and higher in birds reared in a high temperature (P &lt; 0.05) before heat stress. Birds reared in low temperature had higher increase in colonic temperature after heat stress (P &lt; 0.05). Tissue Hsp70 levels were differently affected by rearing temperature, which affected broiler performance more than IT. Lower IT seemed to increase the sensitivity of birds to heat stress at market age. Key words: Heat resistance, Hsp70, incubation temperature, rearing temperature