Effects of incubation temperature pattern on broiler performance

Abstract

During incubation, development of embryos is affected by eggshell temperature ( EST ). A constant EST of 37.8°C has been considered so far to result in most optimal embryo development. However, it can be hypothesized that a higher EST in week 2 in combination with a lower EST in week 3 stimulates embryo development and subsequent grow-out performance. In this study, 468 eggs of a 44-week-old Ross 308 breeder flock were incubated at different incubation temperature patterns in a 2 × 2 factorial arrangement. In week 2, EST was either 37.8°C or 38.9°C, and in week 3, EST was either 37.8°C or 36.7°C. At hatch, chick quality was determined. Thereafter, 320 broilers were grown in 32 pens (8 replicates/treatment) for 6 wk. Weekly BW and ADFI were determined, and at day 40, slaughter yield from 128 broilers (4 per pen) was determined. Results showed that EST in week 2 did not interact with EST in week 3 for any variable. An EST of 38.9°C in week 2 resulted in a 1 mm longer chick length ( P < 0.001) and 0.4 mmol/L lower blood glucose level ( P = 0.04) at hatch than an EST of 37.8°C. Grow-out performance was not affected by EST in week 2 of incubation. An EST of 36.7°C in week 3 resulted in a 1 mm shorter chick length ( P = 0.02), 1.0 mmol/L higher blood glucose level ( P < 0.001), and higher relative heart ( P = 0.01) and stomach weights ( P = 0.03) at hatch than an EST of 37.8°C. Additionally, an EST of 36.7°C in week 3 resulted in lower BW, ADG, and ADFI on slaughter age (all P < 0.03) than an EST of 37.8°C. In conclusion, no interaction between EST in week 2 and 3 of incubation was found for any variable. A higher EST in week 2 had minor effects at hatching and during rearing, whereas a lower EST in week 3 seemed to result in better organ development, but resulted in lower grow-out performance.

Effects of eggshell temperature pattern during incubation on primary immune organ development and broiler immune response in later life

“… Maatjens et al (2016a) showed that a lower EST of 36.7°C from E15 onward resulted in chicks with a higher yolk-free body mass and a higher relative heart weight at hatch than an EST of 37.8°C. In the current experiment, no differences in yolk-free body mass were found when EST was lowered to 36.7°C in week 3 compared with a constant EST of 37.8°C ( Wijnen et al., 2020 ). Moreover, the current study found some indications that the lower temperature in the last week of incubation impaired organ maturation instead of improving embryo development.…”

“…The experimental protocol was approved by the Governmental Commission on Animal Experiments, the Hague, The Netherlands; approval number: 2016.W-0087.001. For further details about material and methods, please review Wijnen et al. (2020) .…”

“…All remaining first-grade chicks (n = 337) were provided immediately with feed and water (within 12 h after hatch), and 40 chicks of each sex per treatment were selected for the grow-out period. For details about exact hatch moments, please review Wijnen et al. (2020) .…”

“…A constant EST of 37.8°C throughout incubation is considered optimal for chick quality at hatch in terms of body length and yolk free body mass ( Lourens et al., 2005 ). However, recently, it was shown that a higher EST of 38.9°C during week 2 of incubation compared with a constant EST of 37.8°C improved embryonic growth rate ( Nangsuay et al., 2016 ) and resulted in a longer chick length at hatch ( Wijnen et al., 2020 ) and improved tibia bone characteristics at slaughter age ( Güz et al., 2020 ). Besides, a lower EST of 36.7°C during week 3 of incubation compared with a constant EST of 37.8°C was shown to result in a higher yolk-free body mass and higher relative weights of the heart, liver, stomach, intestines, spleen (tendency), and bursa ( Maatjens et al., 2016a , Maatjens et al., 2016b ; Wijnen et al., 2020 ).…”

“…However, recently, it was shown that a higher EST of 38.9°C during week 2 of incubation compared with a constant EST of 37.8°C improved embryonic growth rate ( Nangsuay et al., 2016 ) and resulted in a longer chick length at hatch ( Wijnen et al., 2020 ) and improved tibia bone characteristics at slaughter age ( Güz et al., 2020 ). Besides, a lower EST of 36.7°C during week 3 of incubation compared with a constant EST of 37.8°C was shown to result in a higher yolk-free body mass and higher relative weights of the heart, liver, stomach, intestines, spleen (tendency), and bursa ( Maatjens et al., 2016a , Maatjens et al., 2016b ; Wijnen et al., 2020 ). These results suggest that a higher EST of 38.9°C during week 2 in combination with a lower EST of 36.7°C during week 3 of incubation may also affect embryo immune organ development and consequently posthatch immune response, but this was not studied.…”