Effects of light-sources and photoperiod on hemato-physiological indices of broilers grown to heavy weights

Daylight exposure and circadian clocks in broilers: part I-photoperiod effect on broiler behavior, skeletal health, and fear response

The aim of this study was to examine effects of various daylight exposure during the 24-h light-dark (L-D) cycle on growth performance, skeletal health, and welfare state in broilers. Environmental photoperiod and related circadian clock, the 24-h L-D cycle, are important factors in maintaining productive performance, pathophysiological homeostasis, and psychological reaction in humans and animals. Currently, various lighting programs as management tools for providing a satisfactory environmental condition have been used in commercial broiler production. Four hundred thirty-two 1-day-old Rose 308 broiler chicks were assigned to 24 pens (18 birds/pen). The pens were randomly assigned to 1 of 4 thermal and lighting control rooms, then the birds were exposed to (n = 6): 1) 12L, 2) 16L, 3) 18L, or 4) 20L at 15 d of age. Lighting program effects on bird body weight, behavioral patterns, bone health, and stress levels were evaluated from d 35 to d 45, respectively. The birds of 12L as well as 16L groups, reared under short photoperiods close to the natural 24-h L-D cycle, had improved production performance, leg bone health, and suppressed stress reaction compared to the birds of both 18L and 20L groups. Especially, 12L birds had heavier final body weight and averaged daily weight gain (P < 0.05), higher BMD and BMC with longer and wider femur (P < 0.05), lower H/L ratio (P < 0.05), and more birds reached the observer during the touch test (P < 0.05) but spent shorter latency during the tonic immobility test (P < 0.05). Taken together, the data suggest that supplying 12 h as well as 16L of daily light improves performance and health while decreasing stress levels in broilers, making it a potentially suitable approach for broiler production.

Effects of dietary Original XPC on selected blood variables in layer pullets challenged with Mycoplasma gallisepticum,. Poult Sci 2020;99:4373-4383. [PMID: 32867981 PMCID: PMC7598016 DOI: 10.1016/j.psj.2020.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Effects of dietary Original XPC (XPC) on 17 selected blood variables in commercial layer pullets challenged with the virulent, low-passage R strain of Mycoplasma gallisepticum (RlowMG) were investigated. Hy-Line W-36 pullets sourced from M. gallisepticum-clean layer breeders were fed a basal diet with XPC (1.25 kg/metric ton) or without from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with RlowMG. Blood samples were taken immediately before the initial RlowMG challenge at 8 woa and again at 12 woa (4 wk after challenge). At 8 woa, blood pH was lower and glucose concentration was higher in the preassigned challenge treatment groups. At 12 woa, the concentration of oxygen dissolved in the blood was significantly lower in the RlowMG-challenged group than the unchallenged group of birds regardless of dietary treatment. The RlowMG challenge significantly increased blood carbon dioxide partial pressure, calcium, sodium, anion gap, osmolality, glucose, and corticosterone levels but significantly decreased blood oxygen partial pressure, oxyhemoglobin concentration, concentration of oxygen dissolved in the blood, chloride, and pH levels. Because blood pH and glucose concentration at 8 woa were examined before challenge, their baseline values were biased with respect to challenge treatment before treatment was applied. However, the lack of a significant main effect due to diet at 8 woa for blood pH and glucose concentration, along with the other 15 blood variables, indicate that the baseline data with respect to dietary treatment were unbiased, allowing for real dietary effects to be accurately assessed. In conclusion, layer pullets challenged with RlowMG undergo a stress response associated with changes in various physiological blood variables, and a decrease in pH and increase in carbon dioxide partial pressure, in association with a lack of change in bicarbonate, indicates that the stress response caused by the RlowMG challenge was associated with respiratory acidosis. Nevertheless, feeding XPC did not influence the effects of challenge treatment on these postchallenge physiological blood values.

Comparison of an intermittent, short-dawn/dusk photoperiod with an increasing, long-dawn/dusk photoperiod on broiler growth, stress, and welfare

Photoperiod has been shown to significantly affect broiler performance. However, the effects of the traditional 1-min dimming period on broiler growth and welfare are unclear. In this study, 4 consecutive trials were conducted to compare the effects of an intermittent, short-dawn/dusk photoperiod (ISD) to an increasing, long-dawn/dusk photoperiod (ILD) on broiler growth, stress, and welfare. Straight run day-of-hatch Ross 708 × Ross 708 broilers were placed in 1 of 4 commercial broiler barns (2 b of 26,200 birds each per treatment) and grown to 45 D of age. The photoperiod in the ISD treatment consisted of 24L:0D day 0 to 6, 16L:8D day 7 to 13, 12L:4D:2L:6D day 14 to 20, 12L:4D:3L:5D day 21 to 27, 12L:4D:4L:4D day 28 to 41, and 13L:3D:5L:3D day 42 to 45, with a 1-min transition between light and dark periods. The photoperiod in the ILD treatment consisted of 23L:1D day 0 to 7, 16L:8D day 8 to 21, 18L:6D day 22 to 32, and 20L:4D day 33 to 45, with a 1-min light/dark transition period day 0 to 7 and a 30-min transition period day 8 to 45. Treatments were rotated among the barns between trials. On day 45, blood samples were collected from 20 birds/barn (n = 40/treatment) to assess plasma corticosterone (CORT) and heterophil/lymphocyte (H/L) ratio. One hundred birds per barn (n = 200/treatment) were weighed individually and assigned scores for hock burn, foot pad dermatitis, and feather condition on day 45. Trial differences were observed for all measures (P ≤ 0.001). Birds in the ISD treatment were heavier on day 45 (P < 0.001) and had lower hock burn (P = 0.044) and foot pad dermatitis (P < 0.001) scores. Birds in the ILD treatment had lower plasma CORT (P < 0.001) and H/L ratio (P < 0.001). No treatment differences were observed for feather condition (P > 0.05). Overall, birds reared under the intermittent, short-dawn/dusk photoperiod had higher day 45 live body weights and lower hock burn and foot pad dermatitis scores, whereas those reared under the increasing, long-dawn/dusk photoperiod had reduced measures of short-term and long-term stress.

Impact of Housing Environment on the Immune System in Chickens: A Review

During their lifespan, chickens are confronted with a wide range of acute and chronic stressors in their housing environment that may threaten their welfare and health by modulating the immune system. Especially chronic stressful conditions can exceed the individual's allostatic load, with negative consequences for immunity. A fully functional immune system is mandatory for health and welfare and, consequently, also for high productivity and safe animal products. This review provides a comprehensive overview of the impact of housing form, light regime as well as aerial ammonia and hydrogen sulfide concentrations on the immune system in chickens. Certain housing conditions are clearly associated with immunological alterations which potentially impair the success of vaccinations or affect disease susceptibility. Such poor conditions counteract sustainable poultry production. This review also outlines current knowledge gaps and provides recommendations for future research.