Volume 17
Issue 2
Animal Husbandry
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Available Online: http://www.ejpau.media.pl/volume17/issue2/art-08.html
EMU (DROMAIUS NOVAEHOLLANDIAE) LAYING PERFORMANCE AND EGG QUALITY DURING A TEN-YEAR REPRODUCTIVE PERFORMANCE PERIOD
Danuta Szczerbińska, Danuta Majewska, Zofia Tarasewicz, Krystyna Romaniszyn, Anna Sammel, Mateusz Buc³aw
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
This study aimed at determining how the volume of emu egg production and the
egg quality change with the bird age. Observations were conducted over ten successive
emu egg laying seasons. The birds were from own hatching and rearing. At initiation
of observations, the birds were 3 years old and started their 2nd egg laying
season. The egg laying period extended, reaching a maximum (188 days) in 8 years
old female emus, whereas the egg number increased but only to year 6 of layer
life. Older female emus were characterised by low laying performance, which supports
the statement that it is unreasonable to keep emus being older than 7 years for
reproductive purposes. In the first egg laying seasons, the weight of emu eggs
and the shape index significantly changed; then, the value of these indicators
stabilised, being preserved until the end of flock reproductive performance period.
Key words: emu, age, performance, egg quality.
INTRODUCTION
Ostriches, emus and rheas of the subclass Palaeognathae are economically exploited. Among the species being mentioned above, ostriches have the longest history of their use and are of the greatest importance in production. Emus have been kept in farms for about 40 years [4, 8]. Due to a short period of time that has elapsed since the beginnings of their breeding, it is little known on how the performance of flocks has changed in successive reproductive seasons. Furthermore, information on the laying performance of emus being kept in different countries differ sometimes [8, 11, 13]. Emus, like ostriches and rheas, are exploited for a long period of time, sometimes even over a dozen or so years. Therefore, information referring to the egg laying performance of these birds in respective years of their reproductive performance period is important for animal husbandry practice.
The aim of this study was to determine how the volume of emu egg production and the egg quality change with the bird age.
MATERIALS AND METHODS
Observations were conducted over ten successive emu egg laying seasons at an experimental farm of the Department of Poultry and Ornamental Bird Breeding, Western Pomeranian University of Technology in Szczecin. The birds were from own hatching and rearing. In the first two egg laying seasons being analysed, the emu flock under observations consisted of 20 birds (with equal sex ratio), whereas in the next eight egg laying seasons it comprised 19 birds (9 females and 10 males). At initiation of observations, the birds were 3 years old and started their 2nd egg laying season. They were kept under open system, with permanent access to free-range areas, irrespective of weather conditions. The flock was fed granulated complete feed mixtures with the same nutritional value (22% total protein, 10.4 MJ MEN and 7% raw fibre per 1 kg feed) in all reproductive seasons. The feed was fed ad libitum. Feeding of the feed mixture for the egg laying period started about 4 weeks prior to its expected onset. In each reproductive season, eggs were collected every day and then weighed and measured, with the recording of these data in flock egg production book. Based on the measurements of long and short egg axes, the index of egg shape was calculated. The figures collected were analysed statistically, using analysis of variance and Duncan’s multiple range test.
RESULTS AND DISCUSSION
The 3, 4 and 5 years old female emus laid their first eggs in late November (Tab. 1). In the next four seasons, the egg laying started later (in December), while in the last three ones it moved to the first half of January. The number of egg production days increased linearly over next 6 egg laying seasons and then gradually decreased. Only in 6 years old birds, the egg production season was considerably shorter when compared with the one preceding and following it. It is difficult to give a clear explanation of this phenomenon. When excluding the nutritional factors, living conditions and flock hierarchy, which had been the same during the whole period of observations, this might be related with the weather conditions prevailing within the area of West Pomerania Province. A given season was characterised by a relatively high temperature, particularly in the initial period of reproduction, and small amounts of precipitation, when compared with other analysed seasons. The average flock laying period lasted 168.2 days and was longer by about 48 days from that reported by [11] and by approximately 70 days from that reported by [12]. It should be noted that longer egg laying period does not always result in a larger number of laid eggs. The 8 years old female emus continued to lay eggs for the longest time (188 days), which did not induce increased flock productivity.
Table 1. Emu laying performance characteristics according to bird age |
of life |
|||||
The laying performance per female emu changed, from almost 16 eggs in the third year of life to 22 eggs in the sixth year (Tab. 1). In the next seasons, their egg production decreased, with less than 12 eggs being obtained from a layer in year 12 of life. This laying performance is lower when compared with the reference data [9, 11]. According to [8], the egg production of 20–30 eggs per season may be considered good but when a female lays more than 30 eggs, then she is a very good layer. In Poland, such a laying performance has not been reported yet [13]. In the study cited above, female emus laid on average 26 eggs in the fifth year of life. On Australian, Nigerian and Indian farms, 25.3, 35 and 30.2 eggs were obtained from a layer, respectively [1, 7, 12]. In the present study, the laying performance of 7 years old and older female emus was low (9.1–7.7%), which certainly calls into question the advisability of keeping them for such a long time (Fig. 1).
|
Fig. 1. Emu egg laying curve in successive years of life |
In the reproductive seasons being analysed, high lying performance was preserved over next three months (February, March and April), with its peak being observed in March (year 3, 4, 8, 9, 10, 11 and 12 of life). The 5, 6 and 7 years old birds entered into the peak lay period in February (Tab. 2).
Table 2. Emu laying performance [%] in respective months of reproductive season |
The emu egg weight was initially 560 g (Tab. 3). In the next years, it significantly increased. The weight of emu eggs being most often reported in literature ranges from 500 to 680 g [2, 3, 5, 6, 10, 12, 14] and primarily depends on the bird age. Young layers, just after reaching their sexual maturity, lay eggs weighing about 400 g, whereas in successive reproductive seasons older birds lay eggs being heavier by about 300 g. According to [12, 15], the weight of emu egg increases with the bird age, although it stabilises after some time. Own observations suggest that this occurred in the flock under analysis as early as in the fourth month of the bird life and the egg weight did not significantly change over next 8 egg laying seasons.
Table 3. Egg weight and egg shape index according to layer age (x ± SD) |
[g] |
||
a,
b – means in rows
marked with different letters differ significantly (p < 0.05) |
||
The most concise characteristics of the egg shape is its index. It is characteristic for particular bird species and, furthermore, is an individual feature of a given female. It is believed that considerable deviations from a typical egg shape may be the cause of deterioration in hatching results. According to [3], [10] and [13], emu egg shape index amounts to 1.44, 1.49 and 1.55, respectively.
In the present study, the shape of emu egg significantly changed with the bird age (Tab. 3). In the first year of observations, the emus laid eggs with the egg shape index amounting to 1.48. In the next reproductive seasons, it increased to 1.51–1.52. The information reported above indicates that younger birds, up to year 4 of life, lay rounder eggs, whereas in the next reproductive seasons their shape significantly elongates.
CONCLUSION
The egg laying period extended, reaching a maximum (188 days) in 8 years old female emus, whereas the egg number increased but only to year 6 of layer life. Older female emus were characterised by low laying performance, which supports the statement that it is unreasonable to keep emus being older than 7 years for reproductive purposes.
In the first egg laying seasons, the weight of emu eggs and their shape index significantly changed; then, the value of these analysed indicators stabilised, being preserved until the end of flock reproductive performance period.
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Accepted for print: 23.05.2014
Danuta Szczerbińska
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
20 Doktora Judyma St.
71-466 Szczecin, Poland
Danuta Majewska
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
email: Danuta.Majewska@zut.edu.pl
Zofia Tarasewicz
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
Krystyna Romaniszyn
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
20 Doktora Judyma St.
71-466 Szczecin, Poland
Anna Sammel
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
20 Doktora Judyma St.
71-466 Szczecin, Poland
Mateusz Buc³aw
Department of Poultry and Ornamental Brids Breeding,
West Pomeranian University of Technology in Szczecin, Poland
20 Doktora Judyma St.
71-466 Szczecin, Poland
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