Abstract
ABSTRACT This study investigated the effects of broiler chick hatching time on the percentage of the yolk sac and subsequent broiler live performance. Broiler hatching eggs were obtained from a commercial flock at 55 wk of age and were stored for 2 d at 18°C and 75% relative humidity (RH) prior to incubation. Chicks were identified as hatching Early (471-477 h), Middle (480-486 h), and Late (494-510 h). All chicks were removed from the trays at 510 h of incubation. Body weight (BW) and yolk weight (YW) were determined at emergence from the shell (initial hatch time) and at placement on feed. Chicks were permanently identified by hatch time with neck tags, feather sexed, weighed, and introduced to feed and water in litter floor pens. Broiler BW and feed consumption (FC) were then determined 7, 21, and 35 d of age. Mortality was recorded daily. Although the percentage of the yolk was similar at hatch time, it was less in Early compared to Middle and Late chicks at placement (p≤0.05). Broiler chick BW was greater at placement in Late chicks compared to Early and Middle chicks (p≤0.05) but this advantage disappeared by 7 d because Late chicks consumed less feed to 7 d (p≤0.05). Early hatched broilers exhibited greater BW than Late with Middle broilers intermediate at 35 d (p≤0.05). There were no significant differences in feed consumption and feed conversion ratio (FCR) at 35 d of age. Additionally, late hatch chicks exhibited greater mortality. Overall, live performance of Late hatching chicks, judged by mortality and BW at 35 d, was reduced compared to Early hatching chicks.
Highlights
There has always been a natural biological variation in the time that commercial broiler chicks emerged from their egg shells even under optimum conditions of artificial incubation
Corless & Sell (1999) reported reduced Body weight (BW) associated with extended post-hatch holding, but these findings were not consistent with the data presented by Casteel et al (1994), who weighed each group of birds 43 d following placement on feed and water and reported no differences
The objective of the present research was to determine the effects of hatch time on the percentage of the yolk sac at placement and subsequent broiler live performance
Summary
There has always been a natural biological variation in the time that commercial broiler chicks emerged from their egg shells (hatch time) even under optimum conditions of artificial incubation. It has been reported that performance after placement was negatively associated with the time that chicks remained in the hatcher after hatching (Decuypere et al, 2001; Halevy et al, 2003) or that delayed access to feed depressed growth after access to feed (Careghi et al, 2005), and increased mortality (Hamdy et al, 1991). El Sabry et al (2013) reported that early hatching chicks were not able to compensate for their post hatch BW loss and weighed less at 35 d of age. Corless & Sell (1999) reported reduced BW associated with extended post-hatch holding, but these findings were not consistent with the data presented by Casteel et al (1994), who weighed each group of birds 43 d following placement on feed and water and reported no differences.
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