Browsing by Author "Brand Z."

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    A preliminary study on the application of image analysis for the measurement of ostrich eggshell traits
    (2006) Cloete Jr. S.W.P.; Scholtz A.J.; Brand Z.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe)
    Embryonic mortality in developing ostrich embryos has been linked to water loss in eggs during artificial incubation. Traits possibly related to water loss were assessed on shell samples obtained from 512 hatched ostrich eggs. Moderate to high repeatability estimates (0.43 to 0.86) were derived from significant between female variance components for all traits. Two-trait between female correlations were unity or near unity when the same trait was assessed at either the side or the top of individual eggshells. Recordings at either site can thus be considered as the same on the level of the individual female, implying that in future studies only one measurement is needed during the evaluation of the traits investigated in this study. © South African Society for Animal Science.
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    Factors related to shell deaths during artificial incubation of ostrich eggs
    (2007) Brand Z.; Cloetea S.W.P.; Bitown C.R.; Malecki I.A.
    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 ∼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 ∼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.
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    The development of ratite production through continued research
    (2012) Cloete S.W.P.; Brand T.S.; Hoffman L.; Brand Z.; Engelbrecht A.; Bonato M.; Glatz P.C.; Malecki I.A.
    This paper summarises research on farmed ratites and their industries over the past 100 years. Commercial ratite products include meat, skins, feathers and oil. Research on ratites has attempted to enhance the quantity and quality of these products by focusing on the disciplines of breeding and genetics, reproduction and incubation, assisted reproduction, nutrition and animal welfare. Advances in these disciplines are discussed, and directions for future research are provided. © 2012 World's Poultry Science Association.