There is a dearth of scientific information about the physicochemical characteristics of eggs from ratite birds including emus. Thus, an experiment was carried out with 19 laying emu ((Dromaius novaehollandiae) hens, maintained in cages, and divided into two groups according to age, to record morphometric and physicochemical characteristics of the eggs. The width, length, average weight, form index, Haugh unit, yolk index, percentage of egg components, yolk pigmentation, pH of yolk and albumen, and eggshell weight and thickness were recorded. This morphometric characterization was influenced by the age of the hen. Neither the yolk nor albumen pH was influenced by the age of the bird. The eggs from emus that were raised in captivity presented physical and morphometric characteristics that varied with age, although they remained within the ranges of observations that were previously observed for ratite species, but were different from those of domestic chickens. The high fragility and easy rupture of the vitelline membrane in the emu eggs may limit the use of this product in industrial applications. Further studies of emu eggs are needed to improve their suitability for consumption and for the food industry.

RESUMO O objetivo deste estudo foi descrever o desempenho reprodutivo de emus de diferentes idades, agrupados em casais ou em colônias, no Brasil. A duração da estação reprodutiva e a produção de ovos por fêmea alojada foram registradas, a produtividade e as variáveis reprodutivas foram associadas às variações no fotoperíodo. A produção total do lote de aves foi de 180 ovos, e a estação reprodutiva durou 167 dias (abril-setembro), período que apresentou fotoperíodo médio de 11 horas e 11 minutos. Nos grupos de aves de dois, quatro e sete anos de idade, a estação reprodutiva durou 113,, 133 e 82 dias, o número de ovos por fêmea foi de 7,29, 25,67 e 17,3 e a produtividade foi de 31,6, 38,6 e 45,4%, respectivamente. A estação reprodutiva em 2016 ocorreu entre abril e agosto no Brasil. Aves mais velhas tenderam a iniciar o período reprodutivo mais tarde. As observações na taxa de produção podem indicar que quanto mais precoce o pico produtivo, menor o potencial de produção de ovos em emus. Houve a tendência ao melhor desempenho reprodutivo das aves alojadas em casais em comparação com as alojadas em colônias.

ABSTRACT The objective of this study was to describe emus’ breeding performance in Brazil at different ages, grouped in couples or colonies. The duration of the breeding season and the production of eggs per female housed were recorded, and the productivity and breeding variables were associated with the variation of the photoperiod. The total production of the flock was 180 eggs, and the breeding season lasted 167 days (April-September), a period with an average of 11 h and 11min of daylight. The breeding season lasted 113, 133 and 82 days, the numbers of eggs produced per female were 7.29, 25.67 and 17.3, and productivity values were 31.6, 38.6, and 45.4% in the groups of birds with ages of two, four and seven years, respectively. The breeding season in 2016 occurred between April and August in Brazil. Older birds tended to start breeding later. The production rate observations indicated that earlier peak production was associated with lower egg production potential. Finally, there was a tendency for better breeding performance of birds housed in couples than in groups with more birds.