Seasonal differences in fertility and hatchability of eggs produced by the natural mating and artificial insemination methods of chickens.

Abstract

Both the egg and the broiler producers require a continuous supply of commercial chicks as in the best season throughout the year. To comply with their requests, hatching eggs which were assured of high fertility and hatchability should be produced by the breeder.
Seasonal differences of fertility and hatchability of eggs obtained from the natural mating (NM) and the artificial insemination (AI) methods were inquired, using the data during a four-year period from 1960 to 1963 at this Institute and the private hatchery in Chiba prefecture.
Four purebreds, White Leghorn (WL), New Hampshire (NH), Barred Plymouth Rock (BP), White Cornish (WC), and 6 crossbreds, WL ?? ?? xNH_ ?? ?? _, NH ?? ?? ×WL ?? ??, WL ?? ?? ×BP ?? ??, BP ?? ?? ×WL ?? ??, (WC ?? ?? )x(WL ?? ?? xNH ?? ?? ), (WC ?? ?? )×(WL ?? ?? xBP ?? ?? _)( ?? ?? ), were used in this study.
A total of 2, 259, 851 eggs were used in the four years-1, 932, 366 and 327, 485 eggs from the NM and AI groups, respectively.
1. Average percentages of fertility in the NM and AI groups were 83.7 and 81.9, respectively, and no significant difference was found between them.
2. The seasonal ranking of the fertility in the NM group coincided with that of the fertility in the AI. The highest fertility in both the NM and AI groups occurred in spring season, representing 86.5% and 83.9%, respectively. The percentages of the fertility in fall and winter in the NM group were 84.2 and 82.2, respectively, and those in fall and winter in the AI were 83.1 and 81.7, res-pectively. The lowest fertility in both the NM and AI groups was observed in summer, showing 81.8% and 78.9%, respectively. There found a significant difference at 1% level among the seasons in the NM group, and that at 5% level in the AI by the analysis of variance.
In the monthly fertility, the highest in the NM was observed in April and May (86.8%), and that in the AI occurred in October (84.8%). The lowest fertility in the NM was found in August (79.1%), being July (77.9%) in the AI. Significant differences at 1% level were detected among each month in both groups.
3. The percentages of the fertility in each breed in the NM group, as shown in Tables 1 and 2, were 87.3 in WL x WL, 84.5 in WL x BP, 83.1 in BP x BP, 82.8 in NH x NH, 82.1 in NH x WL, 81.8 in WLxNH and 80.6 in BPxWL, and there observed a significant difference at 1% level among these breeds.
4. Average percentages of hatchability of the fertile eggs in the NM and AI groups were 86.8 and 87.7, respectively, and no significant difference was observed between them.
5. The highest hatchability in the NM group was observed in spring (88.7%), the second in winter (87.5%), the third in summer (85.6%), and the lowest in fall (85.5%), showing a significant difference at 5% level among the seasons. The highest hatchability in the AI group occurred in fall (88.5%), the second highest in spring (88.2%), the third in winter (87.3%), and the lowest in summer (86.9%), and no significant difference was found among them. In the monthly differences of the hatchability in the NM group, the value in March was the highest (89.1%) and that in September was the lowest (83.2%), showing a highly significant difference among each month. The highest hatchability in the AI group was observed in May (93.3%), being the lowest in January (82.3%), and there also existed a highly significant difference among each month.
6. In the breed differences of the hatchability in the NM group, crossbred of NHxWL showed the highest (90.6%) and that of WLxBP was the lowest (81.7%), being a significant difference at 1% level among the breeds.
7. While average percentage of the early dead germ in the NM group was 7.5, that in the AI was 9.3. In the seasonal differences, the percentage of the early dead germ in the former group was the lowest in spring (6.2%), showing the highest in summer (8.9%).