Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.Eggs

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Associations of protein intake, sources and distribution on muscle strength in community-dwelling older adults living in Auckland, New Zealand.
    (Cambridge University Press, 2023-08-23) Hiol AN; von Hurst PR; Conlon CA; Beck KL
    Protein intake, sources and distribution impact on muscle protein synthesis and muscle mass in older adults. However, it is less clear whether dietary protein influences muscle strength. Data were obtained from the Researching Eating Activity and Cognitive Health (REACH) study, a cross-sectional study aimed at investigating dietary patterns, cognitive function and metabolic syndrome in older adults aged 65-74 years. Dietary intake was assessed using a 4-d food record and muscle strength using a handgrip strength dynamometer. After adjusting for confounders, in female older adults (n 212), total protein intake (β = 0⋅22, P < 0⋅01); protein from dairy and eggs (β = 0⋅21, P = 0⋅03) and plant food sources (β = 0⋅60, P < 0⋅01); and frequently consuming at least 0⋅4 g/kg BW per meal (β = 0⋅08, P < 0⋅01) were associated with higher BMI-adjusted muscle strength. However, protein from meat and fish intake and the coefficient of variance of protein intake were not related to BMI-muscle strength in female older adults. No statistically significant associations were observed in male participants (n = 113). There may be sex differences when investigating associations between protein intake and muscle strength in older adults. Further research is needed to investigate these sex differences.
  • Thumbnail Image
    Item
    The egg and the nest : obtaining information about the reproductive biology of Apteryx spp. (family: Apterygidae), a cryptic avian taxon, through eggshells : a thesis in partial fulfilment of the requirement for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 2019) Vieco Gálvez, David
    The amniotic eggshell is a bioceramic that can endure the passing of time without major alteration to its physical structure. Not surprisingly eggshells have been found in numerous paleontological excavations around the world and have been used to identify the presence of major taxa and furthermore, to propose hypotheses on how extinct amniotes lived and nested. In the past decades the information that has been obtained solely through eggshells, ranges from inferences of a specie’s habitat, to diet, and nesting behaviours. This information can be obtained using techniques such as microscopy, stable isotopes, ancient DNA, allometry, physics and biochemistry. The possibility of making inferences about an organism’s biology using its eggshells make them an invaluable asset in biological research, as we can obtain information about species that are difficult to observe otherwise, that are endangered, or that are not even alive anymore. It may also allow a comparison of the conditions that affected a species or a group during evolutionary time. In addition, these studies can be done with eggshells obtained after hatching, therefore without compromising the welfare of the study animals. The genus Apteryx (commonly known as Kiwi) is an endemic taxon to the three main islands of New Zealand/Aotearoa. This genus presents five distinct species and several taxa (possible subspecies). Apteryx is a unique clade because of its many unusual characteristics, including that all its species are ground-dwelling nocturnal insectivores, are winter breeders and nest in ground burrows or hollowed trees. Apteryx also presents a unique eggshell that has been part of scientific debates since the 1960’s. The physical features of Apteryx eggshells such as eggshell porosity, thickness and overall gas exchange, do not fit in most allometric models. Hypotheses to address this phenomenon have explored answers in the Apteryx’s extremely long incubation period (74 days or more) and low basal metabolic rate, because these require lesser oxygen. Apteryx are also the only ratite that nest in ground burrows or hollowed trees; all other ratite species lay in scrape type nests. Another oddity of Apteryx is that this genus presents diverse incubation behaviours, with some species having single male incubation, and others male and female incubation, as well as co- operative and group incubation. The mating system of Apteryx has been suggested to be monogamous for some of the species; however, Apteryx females are bigger than males, and at least in two of the Apteryx species, the female does not contribute to incubation whatsoever, suggesting some degree of sex role reversal. This could mean that the mating system of Apteryx revolves around polyandry, or as it is the case of most ratites, promiscuity (or polygynandry). The importance of studying Apteryx lays in its rarity; it is a group of species that defies allometric predictions and presents a wide variety of unusual adaptations. In many respects, it could be said that Apteryx presents adaptations to a niche that in other ecological contexts has been filled by mammals. Terrestrial mammals, except for chiropterans, are naturally absent in New Zealand ecosystems giving the opportunity to birds, which are plentiful in New Zealand, to exploit these niches and adapt accordingly. The series of oddities in Apteryx makes it a “must study” species to explore evolutionary pathways and the extremes in evolution. All Apteryx species are under some category of endangerment and are within the top priorities of restoration and conservation programs in New Zealand, which makes non-invasive methods of study the only way to approach biological and evolutionary questions about the group. This makes the use of eggshells an ideal method to approach biological and reproductive questions in Apteryx. The nests of Apteryx can be easily identified during breeding and non-breeding seasons, and eggshells are frequent remains amongst unoccupied nests; making them accessible with minimal disturbance to the birds. In this thesis, I explored the gaps in knowledge regarding the allometric predictions for the Apteryx eggs and eggshells, re-testing many of these assumptions, considering that there are five species, and not three as was the common belief before 2003. I explored the eggshell using optical techniques (scanning electron microscopy and micro-computed tomography) and experimentally (by determining the water vapour conductance of the eggshell for three of the five species). I found that Apteryx eggshell thickness decreased from north to south, and so did the water vapour conductance, porosity was much higher than what was previously measured in all of the sampled species, and it was higher than the allometric predictions. I found that Apteryx eggs presented a mineral “cuticle” composed by triangular crystals only reported in the literature for the eggshells of a Theropod dinosaur from the early Cretaceous. Morphological characteristics of the eggshell have been used taxonomically by palaeontologists to identify species; I found that it is possible to distinguish between the currently accepted Apteryx species by comparing the eggshell thickness, porosity, cuticle thickness and mammillary area. I next looked at the thermal properties of eggs and nests, using Newton’s law of cooling; I determined the cooling rate of eggs and nests of Brown Kiwi (Apteryx mantelli) and compared it with those of other precocial bird species. I found that Brown Kiwi eggs do not have any adaptation towards heat retention. The nests, however, have good temperature buffering and heat retention capacity. The nest architecture allows the nest to remain cooler than environmental temperature during the day and warmer than environmental temperature at night, which is when the incubating parent leaves the nest to forage. Finally, I examined Apteryx mantelli’s mating system by extracting DNA from the chorioallantoic membrane of hatched eggshells from Operation Nest Egg, a conservation strategy for kiwi. I determined the degree of parentage of the membranes found in several radio- tagged males over a period of five years using fragment analysis, and eight different microsatellite markers. I used very cost-effective techniques that make this study highly replicable and adaptable to other species. I found that Brown Kiwi is not a genetic monogamous species, having multiple contributor parents to a particular nest within and between years. In conclusion, I found that this non-invasive methodology using eggshells of hatched or abandoned eggs is very valuable to study cryptic and endangered species. Therefore, I advocate for further studies of this type, as the information that can be gained about a wide range of species and species behaviours using eggshells, together with relatively cheap techniques is of immense value to science.
  • Thumbnail Image
    Item
    Investigations on the emulsifying properties of egg white protein : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Auckland, New Zealand
    (Massey University, 2018) Onyemachi, Amarachi Delight
    Egg white proteins (EWP) have excellent foaming and gelling functional properties. However, their emulsifying properties are considered poor when compared to soy proteins or milk proteins. Some studies have attributed the poor emulsifying properties to the hydrophobic amino acid groups buried deeply in the interior of the protein conformational structure which is crucial for emulsification. Several methods, such as heat treatment, acid/acid-heat treatment, Maillard reaction, phosphorylation and enzymatic hydrolysis, have been used by some researchers to improve the emulsifying properties of EWP. Preliminary experiments carried out in this study showed that oil-in-water (O/W) emulsions prepared with egg white liquid (EWL) generated lots of visible large aggregates, which no other study has reported. Therefore, it was important to investigate the factors responsible for the formation of these aggregates. Investigations into improving EWP's emulsifying properties could offer opportunities in developing unique and well-defined egg white-based emulsions. The objective of this research project was to produce egg white emulsions with little or no aggregates. This thesis comprises three main parts. The first part focused on the effects of pH and heat treatment on protein aggregation and partial denaturation of proteins in EWL. The second part investigated the effects of heat treatment, oil concentration and protein concentration on the reduction of large visible aggregates in emulsions prepared with EWL. The third part studied the effect of enzymatic hydrolysis on the degree of hydrolysis and emulsifying properties of EWP hydrolysates. The emulsifying properties of original EWP and EWP hydrolysates were characterised in terms of size and zeta (ζ)-potential of emulsion droplets and emulsion stability (e.g. turbidity, microscopic examination and phase separation). Firstly, an experimental study was carried out to evaluate the effect of pH on protein aggregation and precipitation in EWL containing different protein concentrations (0.5, 1, 2, 3, 4, 5 and 10% w/w). It was found that at all the protein concentrations used and at pH less than around 5, ζ-potential values were all positive but decreased as pH increased from 2 to 5. At pH 5, ζ-potential was close to zero (this is the pI of most egg white proteins), while, at pH levels above 5, ζ-potential became negative and increased as pH increased from pH 5 to 11. The spectral absorbance (turbidity) of emulsion samples was also measured at 600 nm which revealed that for all protein concentrations, turbidity was observed to be higher at acidic pH of 3, 4 and 5, indicating the aggregation of EWP. At alkaline conditions of pH 7, 8, 9 and 10 the EWL solutions remained to be transparent. The effect of heat treatment and holding time on the denaturation of EWP in EWL was also studied at different temperatures (57-62oC) and heating times (0-19 minutes). Higher turbidity due to protein aggregation was observed as temperature increased from 57 to 62oC and the heating time increased from 5 to 19 minutes. It is therefore concluded that EWL can be safely pasteurized with little or no denaturation or aggregation at around 57-58oC for less than 5 minutes. At 60oC, it was observed that EWL began to thicken and after 5 minutes coagulation and gelation occurred rapidly. Studies were also carried out to determine the cause of visible large aggregates formed in emulsions prepared with EWL using various factors, such as heat treatment, oil concentration and protein concentration. It was found that heat treatment (60oC for 30 minutes) of 1% (w/w) EWP solution prior to homogenisation had no effect on reduction of aggregates in emulsions containing 5, 10, 15 and 20% (w/w). However, the formation of aggregates was reduced significantly as oil concentration was reduced to 5%. Therefore, the effect of lower oil concentrations (1, 3, 5, 6, 7 and 10% w/w) on the formation of aggregates in emulsions prepared with 1% or 3% EWP concentrations was also investigated. Little or no visible aggregates were formed when emulsions were prepared with 1% EWP and ≤ 5% oil or 3% EWP and 1% oil. Therefore, the results indicated that both protein and oil concentrations played a significant role in the formation of visible aggregates in emulsions prepared with EWP as an emulsifier. The effect of EWP concentrations (0.1, 0.3, 0.5, 0.8, 1 and 2% w/w) on the formation and properties of 5% oil emulsions at ~pH 8 was then investigated. It was discovered that little or no aggregates were produced in emulsions when prepared at 0.1-1% EWP while large aggregates were formed at 2% EWP concentration. The size of emulsion droplets was observed to increase significantly from 242.1 to 703.7 nm as protein concentration increased from 0.1 to 2%. ζ-potential was however not significantly affected by protein concentration and ranged from -35.3 to -39.2 mV. The emulsions prepared were also heat treated at 60-90oC for 30 minutes. No sign of instability with a significant change in the size of emulsions due to heat treatment was observed from all emulsion samples prepared at different EWP concentrations (0.1 - 2%). However, phase separation of the emulsions was observed upon freezing at -20oC and thawing at 4 and 20oC, respectively, at all protein concentrations used. Also, the stability of emulsions was affected by the addition of salts, such as CaCl2 (5-100 mM) and NaCl (50-600 mM), with an increase in droplet size and phase separation. However, the emulsions were relatively more stable to salt-induced flocculation, especially against NaCl, at higher protein concentration (1-2%) than lower protein concentrations (0.1-0.8%). Lastly, the effect of pH 2-10 was also determined from the emulsions prepared at 1% EWP and 5% oil. Extensive droplet aggregation was observed at pH 4 and 5 as expected which is around the pI of most egg white proteins. On the other hand, it was not observed at extremely acidic pH 2.0 and alkaline pH 9-10 and in the control emulsion prepared at pH 8.3. In another part of the study, the effects of enzyme type (bromelain, ficin and papain), enzyme concentration (0.3, 0.5, 1, 2 and 4% w/w; enzyme/substrate (E/S) ratio) and hydrolysis time (0, 30, 60 and 120 minutes) on the degree of hydrolysis (DH) of EWP were investigated by diluting EWL containing 10% EWP to different EWP concentrations followed by adding enzymes into the EWL solutions. DH was observed to increase significantly (p < 0.05) with increasing enzyme concentration and hydrolysis time. A significant difference (p < 0.05) among the different types of enzymes was only observed from the samples with 4% E/S ratio at 120 minutes of hydrolysis time. Papain yielded the highest DH of 7.69% while bromelain and ficin yielded similar DH levels of 5.03% and 4.99%, respectively. The results of SDS-PAGE revealed that the protein bands corresponding to ovalbumin and ovotransferrin disappeared due to their enzymatic hydrolysis into smaller peptides but it was not significantly different between the samples treated with different E/S ratios and hydrolysis reaction times. The effects of enzyme concentration, DH and hydrolysis time on the emulsifying properties of hydrolysed EWP prepared with bromelain and ficin were investigated. Surprisingly, enzymatic hydrolysis significantly improved the appearance of emulsions prepared with EWL containing hydrolysed EWP by producing an emulsion free of aggregates compared to the control emulsions prepared from original EWP which had lots of large aggregates in it. For example, emulsions containing 10% oil and various EWP concentrations (1, 5 and 10%) prepared with hydrolysed EWP (4% E/S, DH 5.16%) yielded smaller droplet size (0.66-0.98 μm) than those of original EWP emulsions (1.22-39.35 μm). However, phase separation occurred immediately after preparation at all protein concentrations (1, 5 and 10%) used while phase separation occurred in only emulsions stabilised with 5 and 10% original EWP. When the emulsions were heat treated at 60-90oC for 0-30 minutes, gelation occurred in the emulsions prepared with 5 and 10% EWP concentrations while the emulsions prepared with 1% EWP had no gelation but had aggregation and phase separation after heat treatment. Emulsions prepared with 1% E/S ficin (DH 4.03% and 4.96%, respectively, after 2 and 4 hours of hydrolysis time) yielded smaller droplets size (0.75-0.87 μm) than droplet size (6.40-7.37 μm) of emulsions prepared with 1% E/S bromelain (DH 4.10% and 4.87% after 2 and 4 hours of hydrolysis time). Droplet size decreased as hydrolysis time increased from 2 to 4 hours for both ficin and bromelain hydrolysates with phase separation occurring the following day after the preparation of emulsions. Thus, DH and enzyme type had some influence on the emulsifying properties of EWP hydrolysates. In conclusion, this study demonstrated that egg white emulsions can be prepared with little or no aggregates using low oil (≤5%) and low protein (1%) concentrations and by enzymatic hydrolysis of EWP. Emulsions containing 5% oil prepared with a relatively higher protein concentration (1-2%) were more stable to destabilization to ionic strength (salt concentration), especially against NaCl. These could lead to production of egg white protein based-emulsions with distinct appearance and characteristics.
  • Thumbnail Image
    Item
    Development of a low-cost automated sample presentation and analysis system for counting and classifying nematode eggs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University, Manawatu, New Zealand
    (Massey University, 2017) Pedersen, Benjamin
    This thesis discusses the concept development and design of a low-cost, automated, sample presentation system for faecal egg counting, and classification. The system developed uses microfluidics to present nematode eggs for digital imaging to produce images suitable for image analysis and classification. The system costs are kept low by using simple manufacturing methods and commonly available equipment to produce microfluidic counting chambers, which can be interfaced with conventional microscopes. This thesis includes details of the design and implementation of the software developed to allow capture and processing of images from the presentation system. This thesis also includes details on the measures taken to correct for the optical aberrations introduced by the sample presentation system.
  • Thumbnail Image
    Item
    Egg white foam : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Auckland, New Zealand
    (Massey University, 2013) Altalhi, Arwa Saleh
    Egg white is extensively utilized as a functional food material in food processing due to the multiple functional roles of egg white proteins such as foaming, gelling and emulsifying properties. The foaming property of egg white has been widely studied using different methods. In this research, two different foaming methods were used to prepare egg white foams by a whipping method using a standard mix beater and a sparging method using a whipped cream dispenser (pressurized dispenser). Egg white is also commercially available in several different physical forms, such as fresh egg white liquid, frozen fresh egg white liquid (EWL) and spray dried egg white powder (EWP). In this study, EWL and EWP solutions were used to compare their foaming ability and foam stability. Various factors affecting on the formation and stability of egg white foam were investigated to understand their impact on the functional properties of egg white as foaming agents under specific conditions, including whipping time and speed, shaking time, temperature, pH, type and ionic strength of salts, thermal treatment and addition of some ingredients (e.g. sugar and hydrocolloids). All foams produced were analysed on the basis of two different parameters of foam properties, such as foamability after preparation and foam stability with time after foam preparation. Foam stability was also analysed by two different aspects, foam volume stability against foam collapse and foam liquid stability against liquid drainage. Another objective of this study was to investigate the application of cooking egg white foam in a microwave oven after the foam preparation with an aim of developing a prototype of value added new products derived from egg white foam. The microbiological stability of egg white was also measured to determine the shelf stability of non-pasteurised and pasteurised egg white solutions with and without added ingredients against microbial growth. Overall the results obtained in this study provide significant insights into the impact of various factors affecting the formation and stability of egg white foam and the potential application of microwave cooking of egg white foam for applications in various food industries. Keywords: Egg white foam, foamability, foam stability, whipped cream dispenser, microwave oven, microbial stability
  • Thumbnail Image
    Item
    Can microbes be contributing to the decline of the North Island Brown Kiwi (Apteryx mantelli)? : a thesis in partial fulfilment of the requirement for the degree of Master of Science in Zoology at Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Hiscox, Jessica Dawn
    North Island Brown Kiwi (NIBK, Apteryx mantelli) are considered nationally vulnerable. Current conservation efforts concentrate on the predator vulnerable chicks, through both intensive predator control and Operation Nest Egg (ONE), a captive hatching and rearing scheme for wild eggs. While these methods are having a positive impact on some NIBK populations, they are expensive to maintain and many NIBK populations are dependent on this intensive management to maintain and increase numbers. Ideally, a point will be reached when less intensive management is needed to maintain NIBK populations. Therefore, ONE is not a permanent conservation strategy; the aim is to phase out intensive management when predator control is deemed sufficient to protect a majority of chicks. However, even with intensive management, overall NIBK numbers are still declining. A potentially significant and previously overlooked factor in this decline could be that NIBK eggs experience high mortality. Indeed 60 per cent of NIBK eggs in the wild do not hatch. Both infertility and predators are unlikely to be major mortality factors in NIBK eggs. Consequently, predator control efforts do little to protect eggs. Research into why NIBK eggs experience such high hatching failure is needed and future conservation work needs to be adjusted in light of the results. The overall objective of this project was to investigate if microbes could contribute to NIBK egg mortality. This project had two aims within this objective: 1. to determine if microbes that could impact hatching success are present on and in NIBK eggs; and 2. to use the results to direct future work and conservation efforts for NIBK. These aims were addressed using four studies, which together support each other in terms of conclusions and give an understanding of the microbes present at different stages in NIBK egg development, in locations throughout the population’s range. The first two studies used 16S rRNA sequencing and/or phenotypic identification methods to identify 1. the bacteria and 2. the fungi on the shells of wild NIBK eggs. Together these provided an understanding of the types of microbes that are present on living eggs during active incubation. In contrast, the third study used 16S rRNA sequencing to identify the bacteria present inside un-hatched infertile NIBK eggs,collected from across the North Island. In the final study, a method was designed to determine if a target bacterium could penetrate through the NIBK egg’s defensive shell. This method was not finalised because the NIBK eggshells could not be sterilised. However, this result showed that NIBK eggshells harbour bacteria that survive even through medical grade cleaning. The consequence of this may mean that bacteria can survive in the shell during adverse conditions, which may result in increased penetration when conditions become suitable. Both the shell and the contents of NIBK eggs in this study had microbes present that could impact hatching success. Of these the most prevalent was Staphylococcus, and while no work has been done on the impact of Staphylococcus on NIBK, members of this genus have been shown to significantly impact the hatching of success of chickens and other birds. The prevalence of Staphylococcus in NIBK eggs indicates that it may be a significant factor in NIBK hatching success and warrants further, focused investigation. That potentially pathogenic genera were isolated from NIBK eggs in this study has consequences for both fieldwork and NIBK conservation. NIBK are known to have dangerous and contagious pathogens in their blood and digestive tracts, such as Cryptococcus spp. Through this research, the potentially dangerous genera Aspergillus, Staphylococcus, Streptococcus and Pseudomonas are added to this list. The Kiwi Best Practice Manual states that ‘thin sterile latex gloves’ should be worn when handing eggs, however, to use dry, bare hands ‘rather than gloved’ when collecting an ONE egg from the wild, to ‘increase sensitivity to holding the egg ‘, as the eggs are cleaned upon arrival at the ONE facility. The eggshells in this project harboured bacteria that survive even through medical grade cleaning; therefore, the cleaning at ONE is unlikely to remove all bacteria. The conclusions of this project are that gloves should be worn at all stages of egg and bird handling, including collecting ONE eggs. This is because of the risk to the handler, as well as the egg. The results of this project also emphasise the need for all equipment used to be cleaned between individuals; this includes callipers, candling torches and weighing bags. In regards to NIBK conservation, the results of this project suggest that predators are not the only factor in NIBK mortality. This project has shown that there are potentiallyserious pathogens present on and in wild NIBK eggs that can kill avian embryos and could be contributing to NIBK egg mortality. We still do not know definitively what is causing the 60 per cent hatching failure in NIBK, but these results highlight the need for egg mortality and microbial factors to be factored in to NIBK conservation and recovery plans. Intensive management of NIBK should be phased out not only when predator control is deemed sufficient to protect the majority of chicks, but when researchers have a better understanding of what other factors contribute to NIBK mortality, at all stages of life. We need long-term, cost-effective ways to keep NIBK populations self-sustaining that protect the eggs as well as the chicks and adults. This means that phasing out of ONE needs to be considered in terms of egg mortality and not just chick survival. More detailed studies are needed to both further identify the microbes present on wild NIBK eggs and to experimentally prove/disprove that NIBK embryos can be killed by these pathogens. This can be achieved by infecting eggs, or by cleaning them.
  • Thumbnail Image
    Item
    Production and incubation in farmed emu (Dromaius novaehollandiae) : a thesis presented in partial fulfilment of the requirements for the degree of Masters [i.e. Master] of Sciences in Ecology at Massey University, Palmerston North, New Zealand
    (Massey University, 1996) Bassett, Suzanne M
    The breeding, egg laying, incubation, chick survival and growth of emu (Dromaius novaehollandiae) were studied in a farmed population. Eggs were laid every 3-5 days between May to October with a peak in July. Birds laid in vegetation, or where absent, near fence lines or by artificial shelters. Clutch size was highly variable (range: 2 - 45) between individuals, and between seasons, and variability increased with the age of the hen. The fate of 578 artificially incubated eggs were recorded. Fertility levels were high (90%) but hatching success was lower. Embryonic mortality was greatest during the first trimester with a second smaller peak at the end of incubation. 434 chicks hatched, representing 68% of all eggs set and 83% of fertile eggs. Weight loss for the entire incubation period was 12.5% and was not correlated with embryo mortality. X-ray and ultrasound equipment were unsuccessful in determining egg fertility. Natural incubation was studied in two emu nests. Egg temperatures averaging 34.1°C and 31.7°C were lower and more variable than those used in artificial incubators. Eggs hatched after 51-54 days. In one nest, deserted eggs cooled to 12.2°C hatched when incubated artificially. Rates of egg turning varied, and two thirds of all egg turns were 90° or less, and only 12% were turned between 158.5° - 202.5°. Water loss during incubation was 10% of the initial egg weight and was greatest at the end of incubation. Males lost up to 30% of body weight during incubation. Survival, sex ratios and growth rates were determined for emu chicks hatching from 637 artificially incubated New Zealand eggs, and 105 eggs imported from Canada for incubation under class 1 quarantine conditions. Survival rates to three months were high (88%). Mortality due to hatch-related problems was restricted to the first week of rearing, and to weeks 8 - 12 when bone deformities became evident. Sex ratios were 50:50. The chicks lost weight after hatching but thereafter grew exponentially. There was no significant difference between male and female hatch weights, or rates of growth, but females grew faster and were heavier up to 18 months. Most birds that grew significantly slower from three weeks of age died within three months. The genetic identity and development of twin emu was described. DNA analysis indicated the twins were identical.