Browsing by Author "Malecki, I. A."
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- ItemDead-in-shell positions of near-term ostrich embryos(South African Society for Animal Science, 2016-12-06) Brand, Z.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Malecki, I. A.; Brown, C. R.The patterns of embryonic development in ostriches, especially in the last stage of hatching, are still not well understood. This study examined between 3468 and 3484 dead-in-shell (DIS) eggs with chicks that died between day 35 and day 42 of artificial incubation. Most DIS chicks were positioned correctly with their heads towards the air cell (52.6%). DIS chicks that positioned their heads near the equator of the egg amounted to 46.5%, while a small percentage (0.9%) were positioned with their upper body towards the bottom of the egg. More DIS chicks tended to pip internally near the equator of the egg (37.6%) than DIS chicks that pipped internally through the membranes into the air cell (34.4%). Most DIS chicks had their heads turned in the correct position from left to right (54.4%), though their beaks were mostly positioned towards the air cell (52.9%). The highest percentage of DIS chicks had their feet in the upwards position (52.4%), while 46% had their feet across or below the head. The wings of all DIS chicks were positioned next to the body. Results from the study showed that most of the DIS chicks were roughly in the correct position, but were still unable to hatch. This warrants future research to investigate the reasons that prevent correctly positioned chicks from hatching.
- ItemFoster parenting, human imprinting and conventional handling affects survival and early weight of ostrich chicks(South African Society for Animal Science, 2012) Wang, M. D.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Bonato, M.; Dzama, K.; Malecki, I. A.The effects of human imprinting and foster parenting by adult ostriches on the survival and growth performance of ostrich chicks were compared to conventional chick-rearing practices in two separate experiments. In the first experiment, the growth rate and survival of chicks imprinted onto humans were compared with those of chicks reared by adult foster parents (n = 100 for both groups). Survival is expressed as proportions, while weights were measured in kg. Treatment did not affect chick survival to 3 weeks (0.90 for imprinted chicks vs. 0.89 for foster chicks), or from 4 to 12 weeks (0.86 vs. 0.83, respectively). Chick weight was not significantly different between groups at 4 weeks, but at older ages, those chicks reared by foster parents consistently outperformed imprinted chicks (means ± SEs being 12.8 ± 0.4 vs. 8.2 ± 0.4 kg at 9 weeks, 37.1 ± 0.8 vs. 19.9 ± 0.80 kg at 18 weeks and 46.2 ± 1.1 vs. 28.6 ± 1.2 kg at 22 weeks). In the second experiment, the treatments consisted of a human-imprinted group of chicks and a group subjected to conventional rearing methods (as customary on the research farm). Chick survival to four weeks was significantly higher for imprinted chicks than for conventionally reared chicks (0.97 vs. 0.84), although chick weight was independent of treatment at 4 weeks (6.27 ± 0.16 kg for the imprinted group vs. 6.18 ± 0.17 kg for the conventional group) and at 15 weeks (respectively 16.5 ± 0.68 vs. 15.2 ± 0.70 kg). Overall, chicks reared by foster parents were heavier than human-imprinted chicks, while early survival of imprinted chicks was better than that of chicks reared by conventional handling. Imprinting thus affected survival of ostrich chicks relative to conventional rearing practices. Because most ostrich chicks are reared with conventional methods, the present study indicates that improvements can be made by adopting alternative approaches. Further studies are needed to ascertain how foster parenting and imprinting may be utilized to optimize chick performance, including the long-term consequences of these practices.
- ItemGenetic parameters for ostrich incubation traits in South Africa(South African Society for Animal Science, 2009) Brand, Z.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Malecki, I. A.; Brown, C. R.Data obtained from a pair-mated ostrich flock located at Oudtshoorn, South Africa, were used to estimate genetic parameters for egg weight (EWT), weight of day-old chicks (CWT), water loss to 21 (WL21) and 35 (WL35) days of incubation, and pipping time (PT) for between 13 806 and 19 913 artificially incubated ostrich eggs during the 2003 - 2006 production years. Data were initially analysed as single traits using ASREML. Covariance components and ratios were subsequently derived from two-trait analyses. Single-trait estimates of heritability (h2) were 0.46 ± 0.08 for EWT, 0.34 ± 0.07 for CWT, 0.34 ± 0.07 for WL21, 0.27 ± 0.06 for WL35 and 0.16 ± 0.04 for pipping time. Estimates of maternal genetic effects (m2) were 0.23 ± 0.12 for EWT and 0.29 ± 0.10 for CWT. A maternal permanent environmental effect amounted to 0.25 ± 0.10 for EWT, 0.12 ± 0.09 for CWT, 0.25 ± 0.04 for WL21 and 0.30 ± 0.04 for WL35. Genetic correlations with EWT amounted to -0.21 ± 0.13 for WL21 and to -0.12 ± 0.14 for WL35. Corresponding correlations with CWT were -0.43 ± 0.07 and -0.54 ± 0.11. Parameters indicate that it should be possible to alter evaporative water loss of ostrich eggs by genetic selection. A feasible selection strategy, however, needs to be devised as it is challenging to effect genetic change in a trait with an intermediate optimum.
- ItemInfluence of incubation management on pipping position, hatching ability and survival of ostrich chicks(South African Society for Animal Science, 2011) Brand, Z.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe); Malecki, I. A.; Brown, C. R.
- ItemMeat quality, skin damage and reproductive performance of ostriches exposed to extensive human presence and interactions at an early age(Springer, 2020) Muvhali, P. T.; Bonato, M.; Engelbrecht, A.; Malecki, I. A.; Mapiye, C.; Cloete, S. W. P. (Schalk Willem Petrus van der Merwe)The effect human presence and interactions performed after hatch to 3 months of age has on ostrich meat quality, skin damage and reproductive performance at a later age was investigated in 416-day-old ostrich chicks. The chicks were allocated to one of the three treatments, which varied with regard to exposure to human presence and care for 3 months post-hatch: HP1—extensive human presence with physical contact (touch, stroking), gentle human voice and visual contact; HP2—extensive human presence with gentle human voice and visual contact without physical contact; S—standard control treatment, where human presence and visual contact were limited to routine management, feed and water supply only. Carcass attributes (carcass weight, dressing percentage and drumstick weight), meat quality traits (pH, colour and tenderness) and skin traits (skin size, skin grading and number of lesions) were evaluated on twenty-four 1-year-old South African Black (SAB) ostriches. Reproductive performance (egg production, average egg weight, number of clutches, clutch size, chick production, average chick weight, fertility and hatchability percentage) were recorded for the first three breeding seasons of 23 SAB pair-bred females from this study. No differences in carcass attributes, meat quality, skin traits and reproductive performance were found between treatments (P > 0.05). It was evident that exposure of day-old ostriches to extensive human presence and interaction as chicks did not influence carcass attributes, meat quality or skin traits at slaughter age, but more importantly, it did not compromise their reproductive performance.