Arklow Co.

Wicklow, Ireland

Arklow Co.

Wicklow, Ireland

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Kent J.P.,Arklow Co. | Murphy K.J.,Arklow Co. | Murphy K.J.,University College Dublin | Murphy K.J.,King's College London | And 4 more authors.
Avian Biology Research | Year: 2013

In general, avian species produce clutches of more than one egg. Differential investment in egg weight and hormone levels is possible and their effects on development and behaviour can be measured. Here we investigated changes in three hormones (testosterone, T; androstenedione, A4 and progesterone, P4) in the outer layer of yolks of infertile domestic goose eggs over the course of a laying season. There was a significant change in the concentration of all three hormones: T and P4 increased in a linear manner across the season whilst A4 increased until mid season and then steadily decreased. The correlation between T and P4 (r=0.613, P<0.001), and between T and A4 (r=0.746, P<0.001) were both positive, but the relationship between A4 and P 4, while positive was not strong (r=0.379, P<0.001), although still significant. The increase in P4 over the laying season is consistent with the transition from a laying to a broody state. The increase in T is consistent with a trade-off for the seasonal decline in egg weight.


Salamon A.,University College Dublin | Salamon A.,Arklow Co. | Kent J.P.,Arklow Co.
Reproduction, Fertility and Development | Year: 2016

Herein we examined the effects of yolk size and ovulation order on the fertilisation of yolks within double-yolked (DY) duck eggs. Single-yolked (SY) duck eggs had high fertility (89.98%), whereas in DY duck eggs fertility was low (51.9% yolks). The yolks closer to the airspace (Yolk 1) in DY eggs had higher fertility (68.82% vs 34.98% for Yolk 2; P<0.001). When only one of the two yolks was fertilised, Yolk 1 was fertilised in 99.12% of those eggs. Yolk 1 is presumed to be the first ovulated. The higher fertility of Yolk 1 is consistent with a primacy effect where the first ovulation has a higher probability of achieving fertilisation. Small DY eggs within the normal SY egg weight range (75-104.9g) had significantly lower yolk fertility (47.91%; n≤550) compared with large (≥105g) DY eggs (54.56%; n≤768; P<0.001). Yolk 1 fertility was lower in small compared with large DY eggs (64.18% vs 72.14%, respectively; P≤0.003). Although Yolk 2 fertility was low, it was not affected by egg size. DY eggs with zero fertilised yolks were significantly lighter than DY eggs with one (P≤0.007) or two (P<0.001) fertilised yolks (i.e. larger DY eggs were more likely to have fertilised yolks). Larger eggs (≥105g) have larger yolks and the evidence here shows that an optimal yolk size is a significant positive factor in achieving fertilization by dislodging spermatozoa, after ovulation, from their storage sites. © CSIRO 2016.


Salamon A.,University College Dublin | Salamon A.,Arklow Co. | Kent J.P.,Arklow Co.
Poultry Science | Year: 2016

Multiple-yolked avian eggs, and especially triple-yolked (TY) eggs, are rare. Over two years, 48,224 duck eggs (Anas platyrhynchos domesticus) were individually candled and seven (0.0145%) TY eggs were identified in a commercial breeding and incubation environment. When compared with double-yolked eggs (Salamon and Kent, 2016) their mean weight, length, width and shape index did not differ, but their dimensions were greater than for single-yolked duck eggs. Yolk fertility in the TY eggs was low (33.33%), and this was attributed to smaller yolk size and early ovulation and/or follicle immaturity. By day 8 of incubation, fertile yolks were positioned next to the airspace. Egg 5 contained one fertile yolk, and the embryo developed to enter the airspace, was consuming all three yolks, but failed to hatch. © 2016 Poultry Science Association Inc.


Salamon A.,University College Dublin | Salamon A.,Arklow Co. | Kent J.P.,University College Dublin
International Journal of Poultry Science | Year: 2013

The external dimensions, weight and contents (yolk, albumen, shell) of Double Yolked (DY) and Single Yolked (SY) eggs of the duck (Anas platyrhynchos domesticus) were measured and compared. The yolks in DY eggs did not differ in weight (p = 0.144), although each double yolk was significantly lighter than the yolk of a SY egg (p<0.001). DY albumen weight was below that expected of a SY egg of comparable weight. However, DY eggs had 24.5% more albumen on the basis of SY yolk weight. In DY eggs, the yolk closer to the airspace (Yolk 1) was heavier in 62.5% of the eggs and heavier yolks are regarded as the first in the ovulation sequence. Thus, DY eggs were divided into two groups based on yolk weight. In Group A, Yolk 1 was heavier. In Group B, Yolk 2 was heavier. Significantly more albumen was found in Group B (Group A: 51.37% vs. Group B: 53.29% albumen; p = 0.031). This supports the mechanical stimulation hypothesis, with the larger Yolk 2 stimulating the secretion of additional albumen by the magnum wall. It is suggested that work with DY eggs could provide a useful non-invasive tool to examine the mechanisms underlying albumen secretion. © Asian Network for Scientific Information, 2013.

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