The Influence of Oviposition Time on Egg Weight, Shell Quality, and Blood Phosphorus

A total of 552 eggs laid over 3 consecutive days by 184 hens were collected and egg and shell weight determined. Time of oviposition for each hen was recorded individually for the first 2 days and was estimated on the third day. Data indicated that the time of oviposition had no direct effect on egg weight and that the heavier eggs in the morning of the first day were due to the greater proportion of the first egg of the sequence being laid in the morning than later during the day. Weight of the shell increased as the eggs were laid later in the day. Significant linear regressions were obtained on the second day (P<.05) and on the third day (P<.01) between time of oviposition and shell weight. Relatively high shell weights in the morning of the first day were also due to the greater percentage of the first eggs of the sequence. Data of percent shell showed the same trend as shell weight. Mean weight of eggs collected on the first day was significantly (P<.01) heavier than the second and third day mean egg weights, supporting the thesis that some of the first day eggs were the first eggs of the sequence. Daily means of shell weight and percent shell decreased on the second day and increased again on the third day. The length of lag in time of oviposition between consecutive days had significant (P<.01) correlations with average shell weight and average percent shell indicating that the longer interval between eggs the more shell is deposited on the egg. However, the length of lag time had no significant effect on the weight of the egg. Serum inorganic phosphorus level 3 hr prior to oviposition was not influenced by the time of day.