Factors affecting ostrich egg hatchability.

Ostrich eggs often have low hatchability (HATCH) rates because they do not lose sufficient weight during incubation. Because egg size, eggshell porosity and thickness (THICK), and length of preincubation egg storage are known to affect egg weight loss during incubation (EWL) and HATCH of chicken eggs, these factors were examined using ostrich eggs. The effects of eggshell porosity (number of large pores per cm2 of shell; LP); and THICK on EWL and HATCH were assessed by categorizing the eggs as having either low, intermediate, or high LP or low, intermediate, or high THICK. Mean EWL was higher (P<0.05) in eggs of the high LP group when compared with eggs in either the low or intermediate LP groups that lost similar amounts of weight during incubation. Mean HATCH was also higher (more than 25%; P<0.10) in eggs with high LP when compared with the HATCH found in eggs having low LP. Eggs from the intermediate LP group had an intermediate HATCH response. Moreover, numbers of LP were positively correlated to both EWL (r2 = 0.64; P<0.0001) and HATCH (r2 = 0.25; P<0.03). Inverse relationships existed between THICK and EWL and between THICK and HATCH according to the order (P< 0.05): eggs of low THICK, highest mean EWL and HATCH > eggs of intermediate THICK, intermediate mean EWL and HATCH > eggs of highest THICK, lowest mean EWL and HATCH. Shell thickness was not correlated to either EWL or HATCH. The influence of egg size on mean LP, THICK, EWL, HATCH, and chick weight (CWT) was assessed. Although THICK was unaffected by egg size, higher LP (P<0.10), EWL (P<0.05), and HATCH (P<0.10) were found in medium-sized eggs when compared with either small or large eggs. The CWT was associated with egg size (P<0.05) according to the order: large eggs, highest CWT > medium eggs, intermediate CWT > small eggs, lowest CWT. Neither EWL nor HATCH was affected by length of preincubation egg storage. Collectively, our findings suggest that 1) ostrich eggs that possess low LP and increased THICK hatched poorly, 2) intermediate-sized eggs hatch best, 3) large eggs produced large chicks, and 4) ostrich eggs can be stored under conditions typically used in the poultry industry for a minimum of 10 d without negatively impacting HATCH.

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