Meat quality, skin damage and reproductive performance of ostriches exposed to extensive human presence and interactions at an early age

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

A study of phenotypic and genetic aspects of reproduction rate in the Tygerhoek Merino flock

Thesis (M.Sc.Agric.) -- University of Stellenbosch, 1986..Full text to be digitised and attached to bibliographic record

An exploratory analysis to determine the impact of fixed effects and to establish genetic parameters across six types of ostrich feathers

CITATION: Brand, Z. & Cloete, S. W. P. 2015. An exploratory analysis to determine the impact of fixed effects and to establish genetic parameters across six types of ostrich feathers. South African Journal of Animal Science, 45(1):20-29, doi:10.4314/sajas.v45i1.3.The original publication is available at http://www.sasas.co.za/journalsAfter a decline in value, ostrich feathers have again become an important part of the income of ostrich producers. Between 22586 and 22753 feather weights, as well as length and width measurements, were obtained from feathers harvested annually during the resting period from a pair-bred ostrich flock maintained at Oudtshoorn Research Farm from 2001 to 2012. The flock consisted mostly of the South African Black (SAB) genotype, but birds from the Zimbabwean Blue (ZB) and Kenyan Redneck (KR) strains were also introduced to study strain effects, as well as the effect of crossbreeding between these genotypes (ZB x SAB; SAB x ZB; KR x SAB; SAB x KR). The feathers were sorted into six feather-type categories, namely floss, short hard body feathers, long hard body feathers, tail feathers, white plumes and short body floss. White plumes had the highest average feather length (AFL), average feather width (AFWD) and square-root-transformed feather weight (SRFW) at 66.2 ± 0.38 cm, 21.2 ± 0.23 cm and 13.66 ± 0.17 g, respectively. A significant decline in AFL took place from 2001 and 2012 (40.0 ± 0.25 cm and 38.7 ± 0.56 cm, respectively), while AFWD stayed fairly constant. Feather weights were higher for males than females resulting in a 24% higher geometric mean for backtransformed feather weights (GMFW) for males relative to females. SAB birds outperformed ZB and KR birds for AFL, AFWD and SRFW. Crosses were intermediate and sometimes comparable with the SAB genotype. Except for long hard body plumes, the weights for all the feather types were higher for the purebred SAB breeders compared with purebred ZB and KR breeders. Heritability estimates of AFL, AFWD and SRFW across the six feather categories were low to moderate at 0.080 ± 0.012, 0.044 ± 0.009 and 0.116 ± 0.017, respectively. The animal permanent environmental effect for the feather traits was lower in magnitude and ranged between 0.025 ± 0.008 for AFL and 0.041 ± 0.012 cm for SRFW. Direct genetic correlations of feather dimensions with SRFW were moderate to high at 0.287 ± 0.117 with AFL and 0.614 ± 0.072 with AFWD. The present results indicate that feather quantity can be improved by genetic selection in ostriches, and further studies should be conducted.http://www.sasas.co.za/exploratory-analysis-determine-impact-fixed-effects-and-establish-genetic-parameters-across-sixPublisher's versio

A comparison between slaughter traits and meat quality of various sheep breeds: Wool, dual-purpose and mutton

The slaughter and meat quality traits of 20-month-old wool (Merino), dual-purpose (Dohne Merino and South African Mutton Merino [SAMM]) and mutton (Dormer) type sheep were compared. Average live weights of SAMM and Dormer sheep were 23% heavier than those of Dohne Merinos which were 28% heavier than Merinos. Fat depths at the thirteenth rib and lumbar regions of Merino and Dohne Merino sheep were lower than those of SAMM and Dormer sheep. The cooking loss, drip loss and shearing value from the M. longissimus dorsi did not differ between breeds. The initial juiciness and sustained juiciness of meat from Merinos were rated significantly lower by sensory analysis. Meat from Dohne Merino was rated significantly more tender for the attribute first bite. It was demonstrated that Dormer and SAMM sheep had heavier but fatter carcasses than Merinos and Dohne Merinos, with differences in meat quality between breeds. © 2012 Elsevier Ltd

Effect of production system on the growth rate, carcass characteristics and carcass composition of Dorper lambs

An investigation on the effect of production system on growth rate, carcass characteristics and carcass composition of Dorper lambs was carried out under South African conditions. The study involved sixty lambs which were divided into two production/feeding groups (feedlot (FL) vs. free-range (FR)) at weaning. Each group consisted of 10 lambs from three gender classes (ewes, rams and castrates). The FL-lambs were fed a commercial pelleted ration while the FR-group grazed natural pastures. The production system x gender interaction indicated that male lambs (castrates and rams) grew twice as fast as ewes under FL-conditions. Gender groups were less pronounced in FR-lambs. FL-lambs produced heavier carcasses, higher dressing percentages and greater carcass fatness levels than FR-lambs. Ram lambs attained heavier slaughter weights and produced heavier carcasses than ewe lambs with castrates being intermediate. Production system did not have an effect on intramuscular lipid concentration, barring a tendency in the Biceps femoris muscle. It was concluded that the FL-diets were generally associated with better lamb growth rates, greater carcass fatness and an improved dressing percentage. Although animal performance was generally improved in the more intensive FL-system, it was also concluded that discerning consumers will likely prefer the more natural (and therefore more ethically acceptable) FR-meat

A comparison between the body composition, carcass characteristics and retail cuts of South African mutton Merino and Dormer sheep

CITATION: Cloete, J. J. E. et al. 2004. A comparison between the body composition, carcass characteristics and retail cuts of South African Mutton Merino and Dormer sheep. South African Journal of Animal Science, 34(1), 44-51.The original publication is available at http://www.sasas.co.za/The body composition, carcass characteristics and retail cuts of 61 Dormers (21 rams and 40 ewes) and 35 South African Mutton Merinos (SAMM) (17 rams and 18 ewes) were determined. A range of carcass measurements was recorded. Since there was no sex x breed interaction, only main effects of breed and sex were considered. There were no differences in slaughter weight between Dormer and SAMM sheep at 18 months of age. Dormers had a 2.7% point higher dressing percentage and a 6.2% higher carcass weight than the SAMM. The Dormer had a higher fat content (kidney fat, back-fat depth) than the SAMM. The eye-muscle area of the Dormers was 13% larger than that of the SAMM sheep. Rams were heavier than the ewes at slaughter. All the traits measured, indicated advantages in favour of rams. Only the saturated, mono-unsaturated fatty acids and polyunsaturated fatty acids to saturated fatty acids ratio differed significantly between the Dormer and SAMM sheep. Based on the fatty acid profile, SAMM meat is slightly healthier than that of Dormer sheep. The higher retail cut weights of Dormers suggested that they were superior to the SAMM as far as meat production was concerned.Publishers' versio

Relative performance and efficiency of five Merino and Merino-type dam lines in a terminal crossbreeding system with Dormer or Suffolk sires

The original publication is available at http://www.sasas.co.za/ABSTRACT: The production performance of ewes was assessed in a terminal crossbreeding experiment involving five Merino and Merino-type dam lines and two terminal crossbreeding sire breeds. Dam lines were SA Mutton Merino (SAMM), SAMM rams crossed to Merino ewes (SAMM cross), Dohne Merino, as well as specialist Merino lines selected for clean fleece weight (FW+) and for an increased reproduction (Rep+). Dormer and Suffolk rams were used as sires. Dual-purpose ewes were heavier than Merinos on average and at the ultimate joining at 3.5 years. Average clean fleece weight for SAMM ewes was approximately half that of Merino ewes while clean fleece weights for Dohne and SAMM cross ewes were intermediate. Differences between progeny in slaughter age, marketing weight, dressing percentage and carcass weight could largely be attributed to the comparison of purebred Merino lines with dual-purpose lines. The slaughter age of lambs from the two Merino lines was between 14 and 21% higher than that of the dual-purpose lines. Lambs from purebred SA Mutton Merino (SAMM) dams also outperformed lambs from SAMM cross ewes for slaughter age, slaughter weight and carcass weight. Considerable variation was found between dam lines for reproduction parameters, but few significant differences were found. Lamb output, defined as total weight of lamb slaughtered per joining, averaged 42.7 kg for SAMM ewes, 44.2 kg for SAMM cross ewes, 39.3 kg for Dohne ewes, 32.9 kg for FW+ Merino ewes and 42.0 kg for Rep+ Merino ewes, but differences between lines only tended to be significant. Sire breed did not affect lamb performance or ewe productivity markedly. An economic simulation indicated large differences in gross income per small stock unit between dam lines, warranting further research on the efficiency of terminal Merino-type dam lines.Publishers' versio

Slaughter traits of Merino sheep divergently selected for multiple rearing ability

The original publication is available at http://www.sasas.co.za/ABSTRACT: Carcass data of 114 19-month-old Merino sheep descended from two lines that were divergently selected for maternal multiple rearing ability (H and L lines, respectively) were used. In study A only ram progeny of the same age were slaughtered, while ewes and rams of the respective selection lines were included in study B. Study A: Mean slaughter weight of H line rams was 12% heavier than that of L line contemporaries. A corresponding difference of 13% was found for carcass weight. Carcass component weights, body measurements, retail cut weights and eye-muscle areas were higher in the H line than in the L line, barring a few exceptions. Adjustment for the higher slaughter weight resulted in most of the line differences being eliminated, but the difference in the loin retail cut remained in favour of the H line. Study B: Mean slaughter and carcass weights of H line animals were respectively 7% and 11% heavier than that of L line contemporaries. Adjustment for the higher slaughter weights of H line animals resulted in most of the differences in the retail cut weight being eliminated, but the hindquarters of H line animals remained heavier than that of L line contemporaries. Line did not affect the moisture, protein, lipid or ash content of the M. longissimus dorsi toracis in study B. The effect of gender on the retail cut weights and proximate analysis was consistent with results from the literature. Selection for multiple rearing ability did not result in any unfavourable responses in retail cut weights or meat chemical properties. Carcasses in the H line, in fact, yielded better in the highly priced loin and hindquarters areas, independently of slaughter weight.Publishers' versio

Genetic parameter estimation of 16-month live weight and objectively measured wool traits in the Tygerhoek Merino flock

Genetic evaluation systems require the accurate estimation of genetic parameters. The genetic, phenotypic and environmental parameters for live weight and objectively measured wool traits were estimated for a South African Merino flock. Records of the Tygerhoek Merino resource flock were used to estimate these parameters. The database consisted of records of 4 495 animals, the progeny of 449 sires and 1 831 dams born in the period 1989 to 2004. The pedigree records used have been collected between 1969 and 2004. Direct heritability estimates (h2a) for 16-month live weight (LW) and objectively measured wool traits ranged from 0.20 for staple strength (SS) to 0.68 for fibre diameter (FD). Maternal heritability estimates ranged from 0.05 for LW and FD, to 0.10 for clean fleece weight (CFW). The proportion of the total phenotypic variance due to the maternal permanent environment variance (c2pe) amounted to 5% for fleece weights. The genetic correlation between animal effects for LW, greasy fleece weight (GFW) and CFW were -0.28, -0.65 and -0.70 respectively. The genetic correlation between LW and CFW was positive, but low at 0.14. The other important genetic correlations among the wool traits ranged from low to high, and were variable in sign ((for GFW with CFW (0.87) and with staple length (SL - 0.18); CFW with clean yield (CY - 0.33) and with SL (0.29); FD with CY (-0.09), with SL (0.15), with SS (0.40) and with standard deviation of FD (SDFD - 0.38): CY with SL (0.33) and with SDFD (0.10); SS with coefficient of variation of FD (CVFD - -0.57) and with SDFD (-0.28); CVFD with SDFD (0.87)). These results suggested that worthwhile responses in the objectively measured traits can be achieved through direct and indirect selection. © South African Society for Animal Science.Articl

A preliminary study on the application of image analysis for the measurement of ostrich eggshell traits

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.Articl