Effects of time of egg collection and pre-incubation treatment on blastoderm development and embryonic mortality in ostrich embr

Author: S.J. van Schalkwyk, Z. Brand, S.W.P. Cloete and C.R. Brown
Year: 1999
Issue: 3
Volume: 29
Page: 154 - 163

The hatching success of artificially incubated ostrich eggs can be influenced by egg management prior to setting the eggs in the incubator. This can include the length of time and conditions to which eggs are exposed in nests prior to collection and the conditions under which eggs are stored prior to incubation. We investigated the effects of time of egg collection, storage position and temperature, and pre-storage conditions on blastoderm development and embryonic mortality during incubation in ostrich eggs. Eggs collected soon after laying tended to have lower levels of embryonic mortality (16.6%) than eggs left overnight in nests and collected the following morning (22.9%). Embryonic mortality was not, however, significantly affected by storing eggs in either the vertical (with the air cell at the top or the air cell at the bottom) or horizontal position. The development of the blastoderm was studied in eggs stored for seven days at 20, 25, 26 and 27°C. Storage at 25, 26 and 27°C resulted in significant increases in blastoderm size after seven days compared to eggs stored at 20°C (12.1-42.1 mm vs 6.0 mm). The effect of storage temperature was tested by subjecting batches of ostrich eggs to five treatments; (1) Stored for <7 days at 17°C immediately after collection (control); (2) Stored at <7 days at 25°C immediately after collection; (3) Incubated at 36°C for 12 h prior to storage at 25°C; (4) Incubated at 36°C for 12 h prior to storage at 17°C; (5) Incubated at 36°C for 48 h prior to storage at 25°C. The latter three treatments simulated eggs that were subjected to high summer temperatures in their nests for varying periods prior to collection. Embryonic mortality was lowest in batches of eggs stored at 17°C immediately after collection (26.7%) and when incubated at 36°C for 12 h before storage at 17°C (31.8%). The embryonic mortality of eggs stored at 25°C immediately after collection averaged 45% but increased significantly to exceed 50% in batches of eggs exposed to 36°C for 12 or 48 h before being stored at 25°C. Pre-heating batches of ostrich eggs at 36°C for 4 h after collection and prior to storage at 17°C resulted in a significant reduction in embryonic mortality compared to eggs not subjected to pre-heating (17.1 vs. 26.2%). Embryonic mortality was not affected by pre-warming ostrich eggs from storage temperature to incubation temperature prior to setting in the incubator.

Keywords: artificial incubation, collection, Embryo mortality, Ostrich eggs, storage
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