Effect of storage periods and conditions on embryonic mortalities and hatchability of artificially incubated ostrich eggs.

1. Despite substantial research, the hatching failure of ostrich eggs remains a key concern for many commercial breeding farms.2. This source of reproductive failure needs to be addressed for ostrich farming to become more profitable.3. Information from 2212 eggs were obtained from the ostrich resource flock at the Oudtshoorn Research Farm (2013-2014). Egg data were divided on a daily basis into two groups: Group 1 included eggs stored from 1 to 13 d in cold storage (CS) at a controlled temperature of 17°C and a relative humidity (RH) of 90%. Group 2 was stored for the same time interval as Group 1, but in a cool room (CR) at ambient temperature to simulate the uncontrolled storage conditions prevalent on most breeding farms.4. Overall embryonic mortalities (OEM) were significantly higher for eggs stored for 1 d (0.38 ± 0.04) and for 8 d or more (between 0.31 ± 0.04 and 0.43 ± 0.04) compared to eggs stored for between 2 and 7 d (between 0.20 ± 0.03 and 0.26 ± 0.04).5. The moisture loss during storage (ML) for eggs stored for 13 d in CS during spring was on average slightly higher (1.28%) than that during summer (0.95%). In contrast, the ML of eggs stored in the CR for 13 d was significantly higher, at 1.59% in spring and 2.08% in summer.6. A general reduction in chick weight occurred for all the seasons (winter, spring and summer) as the number of storage days increased. Ostrich eggs should be stored for between 2 and 8 d under controlled storage conditions for improved hatchability.

Ostrich (Struthio camelus) embryonic development from 7 to 42 days of incubation.

1. Hatching success of ostrich eggs is poor (50-60% of fertile eggs). The current study was designed to identify the timing of key stages in the development of the ostrich embryo. 2. Growth of both embryo and wing length during 42 d of incubation was comparable and approximately linear, with a more or less weekly doubling in size up to 35 d of incubation. 3. The embryo eye size increased more rapidly than beak length and reached a maximum of ~16.2 mm by 28 d of incubation, whereas beak length increased continuously until hatching at 42 d. 4. Linear regression equations were derived from morphometric measurements of embryos between 7 and 42 d. 5. Information stemming from these results can be used to estimate the age of dead-in-shell embryos in an attempt to identify timing of incubation problems that potentially result in low hatchability of fertile eggs.

Synchrotron radiation Mössbauer spectra of a rotating absorber with implications for testing velocity and acceleration time dilation.

Many Mössbauer spectroscopy (MS) experiments have used a rotating absorber in order to measure the second-order transverse Doppler (TD) shift, and to test the validity of the Einstein time dilation theory. From these experiments, one may also test the clock hypothesis (CH) and the time dilation caused by acceleration. In such experiments the absorption curves must be obtained, since it cannot be assumed that there is no broadening of the curve during the rotation. For technical reasons, it is very complicated to keep the balance of a fast rotating disk if there are moving parts on it. Thus, the Mössbauer source on a transducer should be outside the disk. Friedman and Nowik have already predicted that the X-ray beam finite size dramatically affects the MS absorption line and causes its broadening. We provide here explicit formulas to evaluate this broadening for a synchrotron Mössbauer source (SMS) beam. The broadening is linearly proportional to the rotation frequency and to the SMS beam width at the rotation axis. In addition, it is shown that the TD shift and the MS line broadening are affected by an additional factor assigned as the alignment shift which is proportional to the frequency of rotation and to the distance between the X-ray beam center and the rotation axis. This new shift helps to align the disk's axis of rotation to the X-ray beam's center. To minimize the broadening, one must focus the X-ray on the axis of the rotating disk and/or to add a slit positioned at the center, to block the rays distant from the rotation axis of the disk. Our experiment, using the (57)Fe SMS, currently available at the Nuclear Resonance beamline (ID18) at the ESRF, with a rotating stainless steel foil, confirmed our predictions. With a slit installed at the rotation axis (reducing the effective beam width from 15.6 µm to 5.4 µm), one can measure a statistically meaningful absorption spectrum up to 300 Hz, while, without a slit, such spectra could be obtained up to 100 Hz only. Thus, both the broadening and the alignment shift are very significant and must be taken into consideration in any rotating absorber experiment. Here a method is offered to measure accurately the TD shift and to test the CH.

Effect of cottonseed oilcake as a protein source on production of breeding ostriches.

1. South Africa currently produces 70% of the world's ostrich products. The profit margin of South African producers from the sale of ostrich meat, leather and feathers currently stands at 20%, 65% and 15%, respectively. 2. Local producers want to increase the production of ostrich products but keep production costs as low as possible. Maintaining optimal nutrition of breeding stock is necessary to increase the production of ostrich chicks, thereby decreasing the fixed costs per chick. 3. This research examined the impact on ostrich reproduction of replacing soya oilcake (SOC) as a protein supplement with cheaper cottonseed oilcake (CSOC). Although there are no data available on the impact of CSOC feed on ostrich reproduction, it is well known that gossypol, a naturally occurring toxin in cotton plants, negatively affects male reproduction in other monogastric species and that it may also reduce appetite. 4. Ninety-six breeding ostrich pairs were divided into two groups to compare the effects of diet (CSOC and SOC) during the breeding season on ostrich-breeding parameters. The replacement of SOC with CSOC had no significant effect on the number of total eggs produced (47.8 ± 5.3 versus 48.3 ± 5.1 per breeding pair, respectively) or infertile eggs (31.5 ± 3.9 versus 38.0 ± 5.2, respectively). Also, the number of dead-in-shell chicks did not differ significantly between groups (20.2 ± 3.3 versus 26.8 ± 3.8, respectively). 5. Even though none of these breeding parameters differed, the replacement of SOC with CSOC in the diets of breeding birds led to significantly more chicks hatching per hen from breeding birds fed on the SOC (36.1 ± 4.8) than the CSOC diet (17.2 ± 3.8). 6. Although it would thus seem that feeding breeding ostriches CSOC instead of SOC as a protein supplement will have a detrimental effect on chick production, more data are required to deliver a definitive answer.

Embryonic development in the ostrich (Struthio camelus) during the first 7 days of artificial incubation.

1. Early development of ostrich embryos was investigated in relation to time of egg collection and genotype. 2. A total of 321 ostrich eggs were collected during the 2008 and 2009 breeding seasons and the development of the embryo for up to the first 168 h of incubation was described and analysed. A sample of the incubated eggs was weighed and opened daily to investigate developmental changes. 3. In fresh eggs, the blastoderm contained a round, translucent dark area pellucida (AP) in the centre, with a surrounding thin white ring, likely to be the beginning of the area opaca (AO). Fresh eggs were considered infertile if the blastoderm was absent and instead numerous white droplets were present surrounded by vacuoles. 4. The average blastoderm area of a fresh fertile egg was 15.8 mm(2), increasing to 143.3 mm(2) after 2 d of incubation. By 72 h of incubation the area vasculosa (AV) was discernible in the posterior half of the blastoderm. 5. At 48 h of incubation the blastoderm area in eggs from the South African Black genotype (SAB) × Zimbabwean Blue genotype (ZB) crosses (104.5 ± 18.6 mm(2)) was lower than the pure SAB (141.0 ± 10.5 mm(2)), ZB (161.7 ± 13.5 mm(2)) and ZB × SAB crosses (166.1 ± 14.2 mm(2)). 6. Embryo length was 5.01 mm after 72 h of incubation and 14.5 mm after 168 h of incubation. At 168 h of incubation AV lengths for both ZB × SAB (53.2 mm) and SAB × ZB crosses (54.1 mm) were longer than in embryos from the pure breeds. 7. Results from this study can be put to practical use when determining whether eggs are infertile or fertile and also in investigating the age of early embryonic mortalities.

Genetic parameters for eggshell traits in ostriches.

1. A study was conducted on ~14000 ostrich eggs to estimate genetic parameters for eggshell traits that could benefit the hatchability of ostrich eggs. Traits measured included the number of pores on the eggshell, the average diameter of these pores, the total area of pores on the eggshell, permeability (pore area/shell thickness) and eggshell thickness. 2. Heritability estimates ranged from 0·16 for total pore area to 0·41 for the natural logarithm of pore count. The heritability estimates for water loss on 21 and 35 d (WL21 and WL35) of incubation were high at 0·23 and 0·24, respectively. 3. On a genetic level, pore count was negatively correlated with average pore diameter (-0·73) and shell thickness (-0·28), whereas it was positively correlated with total pore area (0·58), WL21 (0·24) and WL35 (0·34). The direct and maternal genetic correlations of pore count with total pore area (0·58) and permeability (0·59) were high and significant. Permeability was positively correlated to WL21 and WL35, both on the direct and maternal genetic levels. 4. The estimated genetic parameters indicate that it should be possible to select for the various eggshell traits in ostrich eggs, or for permeability and water loss. However, as a trait with an intermediate optimum, direct selection for permeability and other eggshell traits would not be straightforward, and the possible application of these results to improve hatchability of ostrich eggs in the future needs consideration.

Physiological parameters of mental health predict the emergence of post-traumatic stress symptoms in physicians treating COVID-19 patients.

Lack of established knowledge and treatment strategies, and change in work environment, may altogether critically affect the mental health and functioning of physicians treating COVID-19 patients. Thus, we examined whether treating COVID-19 patients affect the physicians' mental health differently compared with physicians treating non-COVID-19 patients. In this cohort study, an association was blindly computed between physiologically measured anxiety and attention vigilance (collected from 1 May 2014 to 31 May 31 2016) and self-reports of anxiety, mental health aspects, and sleep quality (collected from 20 April to 30 June 2020, and analyzed from 1 July to 1 September 2020), of 91 physicians treating COVID-19 or non-COVID-19 patients. As a priori hypothesized, physicians treating COVID-19 patients showed a relative elevation in both physiological measures of anxiety (95% CI: 2317.69-2453.44 versus 1982.32-2068.46; P < 0.001) and attention vigilance (95% CI: 29.85-34.97 versus 22.84-26.61; P < 0.001), compared with their colleagues treating non-COVID-19 patients. At least 3 months into the pandemic, physicians treating COVID-19 patients reported high anxiety and low quality of sleep. Machine learning showed clustering to the COVID-19 and non-COVID-19 subgroups with a high correlation mainly between physiological and self-reported anxiety, and between physiologically measured anxiety and sleep duration. To conclude, the pattern of attention vigilance, heightened anxiety, and reduced sleep quality findings point the need for mental intervention aimed at those physicians susceptible to develop post-traumatic stress symptoms, owing to the consequences of fighting at the forefront of the COVID-19 pandemic.

Factors related to shell deaths during artificial incubation of ostrich eggs.

The ostrich industry experiences a high rate of embryonic mortalities during artificial incubation of eggs. Embryonic deaths were studied from data recorded on 37,740 fertile eggs incubated artificially during the 1998-2005 breeding seasons. Roughly 10,000 eggs that sustained embryonic mortalities were classified according to the stage and nature of death, i.e. before 21 days of incubation, after 21 days of incubation, deaths after pipping and rotten eggs. Although infection may have played a role in approximately 1300 rotten eggs, no detailed knowledge of the pathogens involved was available. The remainder of deaths could not be related to pathogens and the deaths were thus generally referred to as non-infectious. The overall level of embryonic mortality in all the eggs studied was 28.5 %. Overall embryonic mortality was affected by incubator, with higher levels (57.0 %) found in eggs incubated in an African Incubator and also in eggs that were transferred between incubators during incubation (38.1%). Overall embryonic mortality also increased in eggs produced by older females. Eggs produced in the autumn had the highest level of embryonic mortality at 53.6 %, whereas eggs produced in the winter had a marginally higher level of embryonic mortalities of 29.2 % compared with eggs produced during summer (27.4 %). Eggs produced by South African (SA) Black males crossed to Zimbabwean Blue females had high levels of embryonic losses of 45.7 %. The embryonic mortality of eggs produced by SA Blacks or Zimbabwean Blue breeding birds subjected to pure breeding was similar at approximately 33-34 %, but embryonic mortality was improved in eggs produced by Zimbabwean Blue males crossed to SA Black females (27 %). Embryonic mortality was increased in eggs that were set directly (32.0 %) or subjected to longer than 6 days of storage (43.5 %). Embryonic mortality was affected by year. The results that were obtained will assist in determining non-infectious factors that have a negative effect on hatching success. Steps can thus be taken to eliminate such factors that may compromise hatching success.

Factors related to high levels of ostrich chick mortality from hatching to 90 days of age in an intensive rearing system.

Ostrich chick mortality was studied in 2522 chicks that were hatched artificially during the 1999/2000 breeding season. High levels of mortality were observed, with 1978 (78.4 %) of these chicks dying before 90 days after hatching. A total of 46.7 % (1,177) of these chicks died before 28 days of age, and a further 30.7% (801) died between 28 and 90 days post-hatching. Chick mortality to 28 days of age could not be conclusively related to sex, day of external pipping or breeder diet. Mortality rates were higher (P< 0.05) at the beginning and end of the breeding season than in the middle months. Differences in mortality levels of chicks incubated in different incubators could be related to the time of the breeding season during which the incubator was mostly used. The regression of chick mortality to 28 days of age on day-old chick mass followed a 2nd-degree polynomial. Chicks with day-old masses below 762.5 g were particularly at risk of dying before 28 days after hatching. Chicks hatching from eggs where excessive water loss to 35 days of incubation (>18%) was recorded were also at risk of succumbing before 28 days of age. Chick mortality percentages for the period from 28 to 90 days of age exceeded 80 % in chicks weighing an average of 1.050 g at 28 days. Mortality percentages declined sharply at higher live masses, to between 20 and 30 % in chicks weighing > or = 1,950 g. This 'core' level of mortality remained throughout, even in the heaviest chicks. It was concluded that the high levels of chick mortality could be related to stress in chicks, resulting from an inability to adapt to the rearing environment. The high subsequent mortality percentages of low live mass chicks that survived to 28 days after hatching could probably be attributed to residual setbacks suffered earlier. Abetter understanding of the underlying principles involved in ostrich chick mortality in intensive rearing environments is required for progress in this field, resulting in more predictable survival rates under these conditions.

Variance components for live weight, body measurements and reproductive traits of pair-mated ostrich females.

Estimates of genetic parameters for reproductive traits, live weight and body measurements were obtained using data from a pair-mated ostrich flock at Oudtshoorn in South Africa. Reproductive traits included total egg and chick production, along with hatchability percentage. Live weight, chest circumference and tail circumferences were recorded at the commencement and cessation of breeding. Heritability estimates (h(2)) were 0.23 for egg production, 0.20 for chick production, 0.10 for hatchability, 0.20 to 0.34 for live weight, 0.12 for chest circumference and 0.30 to 0.38 for tail circumference. Female permanent environmental effects (c(2)) amounted to 0.18 for egg production, 0.18 for chick production, 0.21 for hatchability, 0.32 to 0.36 for live weight and 0.23 to 0.32 for chest circumference. Service sire exerted significant effects only on hatchability (0.22) and subsequently chick production (0.09). Genetic correlations of reproductive traits with live weight were low to moderate, variable in sign, and did not differ significantly from zero. Correlations between live weight recorded at the beginning and end of the breeding season were unity for additive genetic and permanent environmental effects. Egg and chick production were highly correlated genetically and phenotypically, with the genetic correlation exceeding the theoretical limit. In unconstrained analyses, hatchability was positively related to chick production, including at the service sire level. Selection gains in the current flock and future generations are likely. No significant adverse relationships were found between live weight, body measurements and reproductive traits.

The effect of dietary energy and protein levels on production in breeding female ostriches.

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8.5, 9.5 and 10.5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In the second breeding season, groups were given diets with ME of 7.5, 8.5 and 9.5 MJ/kg and protein contents of 105, 120 and 135 g/kg. 3. Body mass of birds on diets of 7.5 and 8.5 MJ/kg ME decreased significantly in the course of the breeding season compared with birds fed on diets with higher energy contents and body measurements decreased, suggesting a loss of body condition. 4. Females fed on diets containing only 7.5 MJ/kg ME produced significantly fewer eggs at significantly longer intervals, resulting in fewer chicks hatched. 5. There was no significant difference in egg mass, initial chick mass, chick survival to one month of age and body mass of chicks at one month. 6. Dietary protein concentrations had no effect on egg production, egg mass, hatchability, initial chick mass, chick survival or chick mass at one month old. 7. The female ostriches regained their original body mass during the 4-month rest period between breeding seasons, but significant differences in some parameters during the second breeding season suggest that they may not have fully recovered their body condition. 8. A dietary energy content of 7.5 MJ/kg proved to have an adverse effect on egg production by breeding female ostriches, and it may be concluded from this study that a diet containing 8.5 MJ ME/kg DM and 105 g/kg protein should be regarded as the minimum that can be used for breeding female ostriches without compromising egg production.

Hatching success of ostrich eggs in relation to setting, turning and angle of rotation.

1. Three trials were designed to study the effects of axis of setting, turning frequency and axis and angle of rotation on the hatching success of ostrich eggs. The joint effects of axis of setting and angle of rotation were investigated in a fourth trial. 2. The hatchability of fertile ostrich eggs artificially incubated in electronic incubators (turned through 60 degrees hourly) was improved substantially in eggs set in horizontal positions for 2 or 3 weeks and vertically for the rest of the time. 3. The hatchability of fertile eggs set in the horizontal position without any turning was very low (27%). It was improved to approximately 60% by manual turning through 180 degrees around the short axis and through 60 degrees around the long axis at 08.00 and 16.00 h. A further improvement to approximately 80% was obtained in eggs automatically turned through 60 degrees around the long axis in the incubator. Additional turning through 180 degrees around the short axis twice daily at 08.00 and 16.00 h resulted in no further improvement. 4. The hatchability of fertile eggs set vertically in electronic incubators and rotated hourly through angles ranging from 60 degrees to 90 degrees around the short axis increased linearly over the range studied. The response amounted to 1.83% for an increase of 10 (R2=0.96). 5. The detrimental effect of rotation through the smaller angle of 60 degrees around the short axis could be compensated for by setting ostrich eggs in the horizontal position for 2 weeks before putting them in the vertical position.