This study was performed to obtain information on yolk utilisation in fasted and fed ostrich chicks post-hatching, explain M. Viljoen at the Department of Agriculture for the Western Cape and co-authors there and at the University of Pretoria and University of Stellenbosch in a paper in Poultry Science.

The fasted trial lasted for seven days, whereas the fed trial continued for 16 days.

Fasted ostrich chicks showed a decrease of 31.3g of bodyweight, with yolk weight decreasing by 28.9g daily after hatching. Yolk weight comprised 28 per cent of day-old ostrich chick bodyweight and decreased to 12 per cent at seven days of age. Only 44.4 per cent of the fasted ostrich chick yolk was assimilated over the trial period.

Crude protein content of the yolk decreased by 13.2g daily. Fat content increased by 1.77 per cent daily, whereas total yolk fat weight decreased with 8.91g daily.

Slaughter weight of fed ostrich chicks increased, with yolk weight decreasing by 16.3g daily. Yolk content for fed ostrich chicks was 26 per cent of bodyweight at two days of age.

Ostrich chicks absorb 30 per cent of yolk over the first four days, 67 per cent after eight days and only deplete the yolk after 14 days post-hatch.

Fasted ostrich chicks absorbed the yolk content at a rate of 28.9g per day, compared with 22.3g per day over the first eight days and 16.3g per day over the 16 days for fed ostrich chicks.

The crude protein content of the yolk decreased by 6.84g daily in fed ostrich chicks, whereas fat content of the yolk increased by 1.39 per cent daily although total yolk fat weight decreased by 6.61g daily.

Yolk weight and total crude protein decreased faster over the first seven days in the fasted ostrich chicks than the fed ostrich chicks, which indicated that the decrease in yolk weight could be attributed to absorption of protein from the yolk.

Fat content decreased faster over the first eight days from the yolk of the fed ostrich chicks than from the yolk of the fasted ostrich chicks, which could indicate that external feed has a positive influence on the absorption of fat from the yolk content, Viljoen and co-authors concluded.

Reference

Viljoen M., T.S. Brand, J.T. Soley and E.A. Boomker. 2012. The composition of egg yolk absorbed by fasted ostrich (Struthio camelus L.) chicks from 1 to 7 days posthatching and for ostrich (Struthio camelus L.) chicks from 1 to 16 days posthatching on a prestarter broiler diet. Poult. Sci. 91(6):1342-1349. doi: 10.3382/ps.2011-01833

Further Reading You can view the full report by clicking here.

June 2012