Effects of incubation 45 versus 55% relative humidity (RH) and early versus late hatching time on heat tolerance of neonatal male and female chicks were studied. Chicks were exposed for 48 h to temperatures of 35 (Experiment 1), 37 (Experiment 2), or 39 C (Experiment 3). Chicks that hatched from eggs incubated at 45% RH were lighter at hatch than chicks that hatched from eggs incubated at 55% RH. Chicks that hatched from eggs incubated at 55% RH lost more body weight and water during heat exposure than those that hatched from eggs incubated at 45% RH. Body weight and water loss during heat exposure of chicks that hatched early and late was similar. However, chicks that hatched late maintained their initial heat production and respiratory quotient better during heat exposure than chicks that hatched early. Body weight and water loss of male and female chicks was similar. At 37 and 39 C, heat production of chicks fell to lower values during the 2nd day of exposure compared with the 1st day. It was concluded that chicks that hatched late, i.e., with a short holding period in the hatcher, and coming from eggs incubated at 45% RH had increased heat tolerance in comparison with the other chicks.

This study was conducted to investigate the effect of acute short term heat exposure on behavioral activities, physiological body reactions, hematological parameters and hormonal profiles of New Zealand White (NZW) and Baladi Red (BR) bucks. Twenty male NZW and BR bucks were divided into two groups; natural winter climate of 19±1°C and 55±5%, Relative Humidity (RH) (control group) and the bucks in the other group were exposed to short term heat stress for 1 h at 37±0.5°C and 20±2% RH. The results indicated that, heat stress decreased (p#0.001) standing and walking behavior and increased (p#0.001) sitting behavior compared with these recorded under control temperature. Moreover, Respiration Rate (RR), Rectal Temperatures (RT) and Time of Sexual Libido (TSL) were significantly increased (p#0.001) following stress. Concentration of plasma testosterone and T 3 were significantly reduced (p#0.001) and cortisol were significantly increased after submission to stress. The RBCs, WBCs, Hb, PCV values were insignificantly reduced and lymphocyte was significantly reduced after stress. In contrast, neutrophils, Neutrophils/Lymphocytes (N/L) ratio were increased (p#0.05) and monocytes were insignificantly increased after the end of heat stress. On the other hand, breeds of rabbit had significant effects on most of the studied traits, especially after heat exposure. The BR bucks were significantly superior; RBCs, WBCs, neutrophils, N/L ratio and monocytes than those recorded in NZW bucks after heat stress. Also, plasma concentration of testosterone were significantly higher but cortisol and T 3 were significantly lower (p#0.05) in BR bucks than those estimated in NZW bucks. Moreover, BR bucks had insignificantly higher walking and lower standing behavior than those recorded in NZW bucks. Also, RR was significantly higher (p#0.001), but RT and TSL were significantly lower (p#0.001) in BR bucks than those recorded in the NZW bucks. Furthermore, the results showed that there were prevalent significant (p#0.05) negative correlation between plasma level of cortisol and each of plasma level of testosterone, RBCs, WBCs counts, standing and walking behavior and significant (p#0.001) positive with RR, RT, TSL and time of sitting behavior. Current results explained that acute short term heat stress, negatively affected of internal environment of rabbit bucks which were reflected in their performance. Also, behavioral traits, sexual libido, hematological parameters and hormonal profile in BR bucks seem to be better than those recorded by NZW bucks after exposed heat stress, which may be explained, why BR breed had more tolerate to heat stress compared to exotic breeds.

Three experiments were performed with 300 neonatal Hisex Brown layer chicks in each. The chicks hatched from eggs incubated at a relative humidity (RH) of 55 or 45%. Within each RH group, two groups were separated based on hatching time (early and late hatch groups). After hatch, 60 chicks served as controls. The other chicks were exposed to 35, 37, or 39 C for 48 h. After exposure, a 4-wk experimental growing period started at Day 2 of age. Chicks exposed to the experimental temperature regimens for 2 days had lower body weights at the end of exposure and grew less than controls during the 1st wk afterwards. At Day 2 of age, chicks hatched from eggs incubated at 45% RH had higher body weights than chicks hatched from eggs incubated at 55% RH. These chicks also had higher body weight gain in the 1st and 2nd wk following exposure to 39 C than chicks hatched from eggs incubated at 55% RH. Chicks hatching late were heavier at Day 2 than early-hatching ones, but body weight gain was similar. Chicks exposed to the experimental temperature regimens had lower rectal temperatures than controls at the end of the 1st and 2nd wk. Incubation RH, hatching time, and sex did not affect feed intake, feed conversion, or rectal temperature. After exposure to 39 C, fewer chicks that had hatched from eggs incubated at low RH died compared with chicks that had hatched from the 55% RH group. Early-hatching chicks had a significantly higher risk of dying than late-hatching ones.

This study was designed to evaluate the effects of different artificial light intensity; 10, 50, 250, 500 lux and natural day light (NDL, average 375 lux) from 3-18 week of age on behavioral activities, plumage conditions, productive and physiological traits for grower and layer of Japanese quail. A total of 270 Japanese quails chicks (3 week old) were randomly assigned to five treatment groups according to different light intensities. The results showed that the birds subjected at NDL and 250 lux spent significantly more time standing than those recorded in 50 and 500 lux groups. Also, birds kept at 500 lux spent significantly more time walking compared with other groups. The lowest plumage deterioration was detected in birds kept under NDL compared with other experimental groups. The heavier body weight (p#0.05) at 6 weeks and weight gain from 3-6 weeks were detected for birds reared at NDL and 250 lux compared with 500 lux and did not significant with the rest of the experimental groups. While, Hen Day Egg Production (HDEP) and Total Egg Mass (TEM) were linearly increased beginning of 50 lux with increasing light intensity. Fertility percentage was significantly higher in 250 lux group than in 50 lux and was not significant with the other groups. Hatchability percentage was significantly decreased in 10 lux group compared with the other groups. Serum level of T 3 was decreased linearly with increasing light intensity. Birds kept at 500 lux had reduced overall number of Ovarian Yellow Follicle (OYF), relative weight of ovaries and testes and cloacal gland area compared with the other groups. From our results, it could be concluded that neither high light intensity (500 lux) nor low light intensity (10 lux) had a positive effect on most traits. Therefore, to maximize productive, reproductive parameters and increase revenue economic may be by using moderate artificial light intensity if we used closed-side housing system or NDL if we used open side housing system for production of Japanese quail.

No abstract

The effects of injection of saline (0.9% NaCl) with or without vitamin C on heat tolerance of newly hatched chicks were studied. Sham-treated chicks served as controls. The chicks hatched from eggs incubated at 45% RH or 55% RH. Between the first and the second treatment, a 48-h exposure period to a constant environmental temperature of 30 degrees C took place. Consecutively, production parameters were studied during a 4-week growing period. During heat exposure, chicks hatched from eggs incubated at 45% RH lost less body weight than those from eggs incubated at 55% RH. At the end of exposure, body temperature was lower in chicks hatched from eggs incubated at 45% RH compared to 55% RH. Incubation RH did not affect growth rate, feed intake, feed conversion and mortality during the post-exposure growing period. Injection of saline with or without vitamin C before exposure resulted in a higher body weight after heat exposure compared with controls. Injection of saline enhanced body weight to a greater extent than saline with vitamin C. Injection of either solution before or after exposure did not affect production parameters in the 4-week period after exposure, except for mortality. Mortality of sham treated chicks was higher than that of once or twice injected chicks. It is concluded that saline injection increased heat tolerance, but that addition of vitamin C did not have any contributing positive effect. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Cytokines are proteins excreted by cells that play an important role in the activation and regulation of other cells and tissues during inflammation and immune responses. They act as humeral regulators which modulate the functions of individual cells. Unlike hormones, cytokines are produced by cells which are not organized in specific glands which act to affect biological cases such as inflammations. The biological activities of cytokines are mediated by specific membrane receptors which can be expressed on substantially all cell types. The mechanism by which receptor occupation by cytokines results in the generation of a signal through the receptor is not completely understood. But it is frequently possible to observe the order of cytokine actions with some early cytokines preactivating cells so that they can then respond to later acting cytokines. All cytokines act through receptors on the surface of the target cells, which may lead to the activation or down regulation of the cell's activity. The main function of cytokines is in the activation and regulation of the cells of immune system. Cytokines are produced by variety of cell types, depending on the cell's function. For instance, epithelial cells may produce cytokines involved in the generation of inflammation, the so-called proinflammatory cytokines such as interleukin-6 (IL-6) or IL-8, whereas macrophages may produce both proinflammatory cytokines and cytokines involved in the activation and regulation of T helper lymphocytes (Th) in the development of an adaptive immune response. Cytokines have been classified into a number of groups based on their activity and the cells they are produced by or act upon. These groups include interleukins (IL), interferons (IFN), tumour necrosis factors (TNF), transforming growth factors (TGF), migratory inhibitory factors and the smaller chemokines. It is also possible to broadly categorise cytokines on their activity and this may be more beneficial in understanding the nature of their general activity. The use of molecular techniques is enabling the role of cytokines in the pathogenesis of diseases. This will lead to further understanding of the role the immune system, and in particular cytokines. In this review article the types and functions of chicken cytokines will be accurately displayed.