اثر وزن و مدت زمان نگهداری بر pH آلبومین و قدرت جوجه درآوری تخم مرغهای قابل جوجه کشی

This study aims to determine the effects of storage period and egg weight on albumen pH and hatchability of hatching eggs. For this purpose, the eggs produced by native breeder hens (28 - 31 weeks of age) were used in a completely randomized design with a 3 × 8 factorial arrangement. The main factors were 3 egg weight ranges (46 - 49, 50 - 52 and 53 - 56) and 8 storage periods (1, 3, 6, 9, 12, 15, 18 and 21 days). Temperature and relative humidity of storage room was 16 ± 1.5 °C and 75 - 85%, respectively. Storage period had significant effects on albumen pH (P < 0.001), hatchability (P < 0.001), chick weight (P < 0.001), chick weight as a percentage of egg weight (p < 0.01) and late embryonic mortality (15 - 21 days of incubation) (P < 0.05). As the storage period increased from one to twenty-one days, hatchability of fertile eggs decreased from 89.4% to 42.7%, albumen pH, chick weight, chick weight as a percentage of egg weight and late embryonic mortality also increased from 9.25, 34.8 gr, 67.5% and 5.19% to 9.49, 35.9 gr, 70.1% and 42.7%, respectively. Egg weight of hatching eggs also was significantly related to hatchability (P < 0.05), chick weight (P < 0.001), chick weight as a percentage of egg weight (P < 0.01) and late embryonic mortality (P < 0.05). Heavy eggs (53 - 56 gr) had lower hatchability than medium and small weight groups (64.2% Vs. 68 and 69.5%, respectively). As the weight of hatching eggs increased, chick weight (p < 0.001), chick weight as a percentage of egg weight (P < 0.01) and late embryonic mortality (P < 0.05) also increased. The results indicate that, under the conditions of this experiment (16 ± l.5 °C and 75-85% relative humidity), highest hatchability can be obtained with eggs of medium weight range and storage periods of less than three or four days.