Abstract
Eggs from a meat-type breeder flock at 29 and 35 weeks of age were used in two trials to investigate the effects of in ovo feeding of carbohydrates (CHO) and high incubation temperature (37.5 vs. 38.5 °C (HIT)) during days 16 to 21 of incubation on hatchability traits, chick weight at hatch as an absolute value or as a percentage of egg weight (CWTP), hatching time, glycogen concentration in the liver and pectoral muscle, and glycogen index of hatched chicks. The treatments were a non-injected control, a positive control where saline was injected, or saline with a CHO mixture at 50, 100, 150, 200 and 250 mg/egg. The CHO mixture was maltose, sucrose and dextrin in a proportion of 1 : 1 : 8 by weight. As a result of this study, in ovo feeding of CHO increased CWTP without altering hatchability traits. Hatched chicks from eggs injected with 250 mg CHO/egg had a higher liver glycogen content and glycogen index than those of the control treatments. The high incubation temperature reduced chick weight, hatching time, liver glycogen and glycogen index of the hatched chicks. In ovo feeding of 100 and above mg CHO/egg overcame the negative effects of HIT. Hatched chicks from older hens had a lower concentration of liver glycogen and glycogen index than those of younger hens. It was concluded that in ovo feeding of CHO improved the weight and glycogen index of hatched chicks and those of the HIT treatment, and older hens negatively affected the glycogen index of hatched chicks.
Highlights
The effects of in ovo feeding of CHO and high temperature during the last stage of incubation on hatchability traits, and weight and glycogen status of hatched chicks are shown in Tables 1 to 3, respectively
Hatched chicks from eggs injected with 250 mg CHO/egg had a higher (P
The significant interaction between in ovo feeding of CHO and incubation temperature on CWT and CWTP, and liver glycogen concentration and glycogen index of hatched chicks indicated that in ovo feeding of 100 and above mg CHO/egg alleviated the growth depression and restored glycogen status of hatched chicks incubated under high temperature
Summary
Whilst fatty acids of yolk lipids are the predominant energy source during the second half of incubation (Noble & Cocchi, 1990; Sato et al, 2006), a large mobilization of yolk nutrients into the embryo occurs during the peri-hatch period (Richards, 1991; Vieira & Moran, 1999) and is utilized during the hatching process (Sell, 1996; Uni et al, 1998; Chotinsky et al, 2001; Geyra et al, 2001). Glycogen stored in the liver and muscles of embryos is the main energy source during the hatching process (Donaldson, 1995; Moran, 2007).
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