Incubation lighting schedules and their interaction with matched or mismatched post hatch lighting schedules : Effects on broiler bone development and leg health at slaughter age

The incidence of leg pathologies in broiler chickens with a developmental origin may be decreased by stimulating embryonic bone development through lighting schedules during incubation, but this may depend on post hatch lighting conditions. Aim was to investigate how lighting schedules during incubation and their interactions with matched or mismatched lighting schedules post hatch affected bone development and leg health at slaughter age. In a 3 × 2 factorial designed experiment, eggs were incubated under continuous cool white LED light (Inc24L), 16 h of light, 8 h of darkness (Inc16L:8D), or continuous darkness (Inc24D) from set till hatch. After hatch, broilers were housed under continuous light (PH24L, to match Inc24L and Inc24D) or 16 h of light, 8 h of darkness (PH16L:8D, to match Inc16L:8D). Gait scores were determined on D21, D28, and D34. After slaughter on D35, legs were scored for varus-valgus deformities, rotated tibia, tibial dyschondroplasia, bacterial chondronecrosis with osteomyelitis (BCO), epiphyseolysis, and epiphyseal plate abnormalities from 1 = absent to 4 = severe. Femur and tibia dimensions and mineral density were determined. Inc24L led to more epiphyseal plate abnormalities than Inc16L:8D or Inc24D. Inc24D led to more BCO than Inc16L:8D. Gait scores on D21, D28, and D34, and bone dimensions did not differ between treatments. Inc24L led to higher femur mineral density than Inc24D with Inc16L:8D intermediate. Providing a chicken with a matched post hatch lighting schedule did not affect most measurements of bone development and health. It can be concluded that a circadian incubation lighting schedule may improve leg health in broilers

Incubation lighting schedules and their interaction with matched or mismatched post hatch lighting schedules : Effects on broiler bone development and leg health at slaughter age

The incidence of leg pathologies in broiler chickens with a developmental origin may be decreased by stimulating embryonic bone development through lighting schedules during incubation, but this may depend on post hatch lighting conditions. Aim was to investigate how lighting schedules during incubation and their interactions with matched or mismatched lighting schedules post hatch affected bone development and leg health at slaughter age. In a 3 × 2 factorial designed experiment, eggs were incubated under continuous cool white LED light (Inc24L), 16 h of light, 8 h of darkness (Inc16L:8D), or continuous darkness (Inc24D) from set till hatch. After hatch, broilers were housed under continuous light (PH24L, to match Inc24L and Inc24D) or 16 h of light, 8 h of darkness (PH16L:8D, to match Inc16L:8D). Gait scores were determined on D21, D28, and D34. After slaughter on D35, legs were scored for varus-valgus deformities, rotated tibia, tibial dyschondroplasia, bacterial chondronecrosis with osteomyelitis (BCO), epiphyseolysis, and epiphyseal plate abnormalities from 1 = absent to 4 = severe. Femur and tibia dimensions and mineral density were determined. Inc24L led to more epiphyseal plate abnormalities than Inc16L:8D or Inc24D. Inc24D led to more BCO than Inc16L:8D. Gait scores on D21, D28, and D34, and bone dimensions did not differ between treatments. Inc24L led to higher femur mineral density than Inc24D with Inc16L:8D intermediate. Providing a chicken with a matched post hatch lighting schedule did not affect most measurements of bone development and health. It can be concluded that a circadian incubation lighting schedule may improve leg health in broilers

Effects of lighting schedule during incubation of broiler chicken embryos on leg bone development at hatch and related physiological characteristics

Providing a broiler chicken embryo with a lighting schedule during incubation may stimulate leg bone development. Bone development may be stimulated through melatonin, a hormone released in darkness that stimulates bone development, or increased activity in embryos exposed to a light-dark rhythm. Aim was to investigate lighting conditions during incubation and leg bone development in broiler embryos, and to reveal the involved mechanisms. Embryos were incubated under continuous cool white 500 lux LED light (24L), continuous darkness (24D), or 16h of light, followed by 8h of darkness (16L:8D) from the start of incubation until hatching. Embryonic bone development largely takes place through cartilage formation (of which collagen is an important component) and ossification. Expression of genes involved in cartilage formation (col1α2, col2α1, and col10α1) and ossification (spp1, sparc, bglap, and alpl) in the tibia on embryonic day (ED)13, ED17, and at hatching were measured through qPCR. Femur and tibia dimensions were determined at hatch. Plasma growth hormone and corticosterone and pineal melatonin concentrations were determined every 4h between ED18.75 and ED19.5. Embryonic heart rate was measured twice daily from ED12 till ED19 as a reflection of activity. No difference between lighting treatments on gene expression was found. 24D resulted in higher femur length and higher femur and tibia weight, width, and depth at hatch than 16L:8D. 24D furthermore resulted in higher femur length and width and tibia depth than 24L. Embryonic heart rate was higher for 24D and 16L:8D in both its light and dark period than for 24L, suggesting that 24L embryos may have been less active. Melatonin and growth hormone showed different release patterns between treatments, but the biological significance was hard to interpret. To conclude, 24D resulted in larger leg bones at hatch than light during incubation, but the underlying pathways were not clear from present data.</p

Effects of lighting schedule during incubation of broiler chicken embryos on leg bone development at hatch and related physiological characteristics

Providing a broiler chicken embryo with a lighting schedule during incubation may stimulate leg bone development. Bone development may be stimulated through melatonin, a hormone released in darkness that stimulates bone development, or increased activity in embryos exposed to a light-dark rhythm. Aim was to investigate lighting conditions during incubation and leg bone development in broiler embryos, and to reveal the involved mechanisms. Embryos were incubated under continuous cool white 500 lux LED light (24L), continuous darkness (24D), or 16h of light, followed by 8h of darkness (16L:8D) from the start of incubation until hatching. Embryonic bone development largely takes place through cartilage formation (of which collagen is an important component) and ossification. Expression of genes involved in cartilage formation (col1α2, col2α1, and col10α1) and ossification (spp1, sparc, bglap, and alpl) in the tibia on embryonic day (ED)13, ED17, and at hatching were measured through qPCR. Femur and tibia dimensions were determined at hatch. Plasma growth hormone and corticosterone and pineal melatonin concentrations were determined every 4h between ED18.75 and ED19.5. Embryonic heart rate was measured twice daily from ED12 till ED19 as a reflection of activity. No difference between lighting treatments on gene expression was found. 24D resulted in higher femur length and higher femur and tibia weight, width, and depth at hatch than 16L:8D. 24D furthermore resulted in higher femur length and width and tibia depth than 24L. Embryonic heart rate was higher for 24D and 16L:8D in both its light and dark period than for 24L, suggesting that 24L embryos may have been less active. Melatonin and growth hormone showed different release patterns between treatments, but the biological significance was hard to interpret. To conclude, 24D resulted in larger leg bones at hatch than light during incubation, but the underlying pathways were not clear from present data.</p