EGG WEIGHT INFLUENCE ON SOME EGG CHARACTERS AND HATCHLING BODY WEIGHTOF GIMMIZAH CHICKEN STRAIN

The present experiment was carried out for studying the effect of egg size on egg shape index, egg volume, egg surface area, egg weight loss during incubation and their relations with chick body weight at hatch and at pull out. Eight hundred and fifty two hatching eggs obtained from Gimmizah chickens aged 49 weeks were divided into 6 groups based on egg weight with 5 grams differences namely as 1(<44 ), 2 (44- 48.99), 3 (49 – 53.99), 4 (54 – 58.99), 5 (59 – 63.99) and 6 (≥ 64.00). The obtained results showed that egg weight over 64 grams had the highest significant egg shape index compared to other egg weight groups. Moreover, eggs groups for weights between 59-63.99 and ≥ 64.00had significant increase on both egg volumes and egg surface areas compared to the rest egg groups. Also, negative correlations between egg weight and egg shape index were observed for egg groups < 44, and ≥ 64.00 grams. Moreover, highly significant correlations between egg weight and egg surface area were detected for groups of eggs weighing 44-48.99, 49-53.99, 54-58.99 and 59-63.99 grams. The accumulated egg weight loss% through the setting phase represented significant increase for eggs weighing more than 64 grams compared with those for all the rest egg categories. The increase of egg weight has a significant (p<0.001) influence on chick body weight either at hatch or at pull out as they increased with the increase of egg weight. Moreover, chick body weight loss % inside the hatcher was significantly decreased with the increase of egg weight. The correlations between egg weight and both of chick body weight at hatch are significant (p=0.001) among all experimental groups. The multiple regression equations implied the importance of egg weight and egg weight loss during incubation on chick body weight at hatch and at pull out. Thus, it could be concluded that separating hatching eggs basing on egg weight may be advisable to obtain the best hatchling weight.