Carcass characteristics and meat quality of progeny of five Merino dam lines, crossed with Dormer and Suffolk sires

This study details the slaughter traits of lambs born from a terminal crossbreeding experiment that involved five Merino type dam lines crossed with Dormer and Suffolk sires. Dam lines included dual purpose types; South African Mutton Merino (SAMM), Dohne Merino, SAMM rams crossed to commercial Merino ewes (SAMM cross) and specialist Merino lines selected either for clean fleece weight (FW+) or for an increased fertility (Rep+). Data include between 228 and 483 individual records, depending on the trait. The unadjusted fat depth 25 mm from the midline at the 13th rib of lambs from dual-purpose ewes was between 22 and 32% greater than that of lambs from FW+ Merino ewes. Progeny from Rep+ Merino ewes showed a closer resemblance to the progeny of dual-purpose breeds than to those of FW+ Merino ewes in this instance. Adjustment for slaughter weight eliminated these differences. The initial pH of meat from progeny of FW+ Merino ewes was lower than that from progeny of dual-purpose ewes, and Rep+ Merino ewes. No differences in Warner-Bratzler shear values of the meat were found between the different crosses. Crossbred progeny of the Merino lines performed satisfactorily for all the traits considered, and will not be discriminated against in the market. No conclusive differences in favour of either sire breed were found. Keywords: Dohne Merino, meat quality, SA Mutton Merino, terminal crossbreeding South African Journal of Animal Science Vol. 38 (4) 2008: pp. 355-36

A comparison between the effects of two cropping methods on the meat quality of impala (Aepyceros melampus)

Impala (Aepyceros melampus) constitute one of the most commercially important species in game farming in South Africa. The purpose of this study was to compare the effects of day and night cropping on the meat quality characteristics of impala. Emphasis was placed on the influence of the cropping method on muscle pH45 (45 minutes post mortem), pHu (ultimate pH), pH decline, and the related influence on drip loss, cooking loss, toughness and colour of the meat in the M. longissimus lumborum. Measurements taken from 16 animals cropped at night were compared to those taken from 24 animals cropped in daytime. A mean pH45 of 6.67 + 0.11 was recorded for the night cropped animals compared to a mean pH45 of 6.55 + 0.23 for the day cropped animals. A mean pHu of 5.39 + 0.08 for animals cropped at night was recorded compared to a mean pHu of 5.45 + 0.11 for the animals cropped in the day. Regression analysis showed the rate of pH decline to be slower in the night cropped animals compared to those cropped in the day. This persisted when the pH values were adjusted to correct for ambient temperature. The cooling rate of the M. longissimus lumborum was twice as fast in the night cropped group. Shear force values and drip losses respectively, for the night-cropped animals were 19.11 + 5.68 g/mm2 and 2.93 + 1.59%, whereas for the day cropped animals the values were 23.42 + 8.13 g/mm2 and 4.15 + 2.34%. The results of this study indicate that night-time cropping does have a beneficial effect on certain meat quality parameters. Keywords: Meat quality, Impala, Cropping methods South African Journal of Animal Science Vol.33(4) 2003: 233-24

Effect of hot-deboning on the physical quality characteristics of ostrich meat

The effects of hot-deboning on the physical meat quality characteristics and shelf-life of ostrich m. gastrocnemius, pars interna (gastroc) and m. iliofibularis (iliof) were investigated during 42 days (d) of refrigeration. The hot-deboned gastroc was initially tougher than the cold-deboned muscles, while hot-deboning had no significant effect on the shear force of the iliof. After 14 d of refrigerated storage, there was no difference in tenderness between the hot- and the cold-deboned muscles. Hot-deboning caused significantly more purge (3.4 ± 2.33%) compared to cold-deboning (2.1 ± 2.06%) throughout the 42-day storage period. All muscle samples were acceptable in terms of Aerobic Plate Counts (APC < 104 cfu/g) and E. coli (E. coli < 101 cfu/g), based on the South African Standards for the microbiological monitoring of meat for refrigerated export. It was concluded that hot-deboning did not influence the shelf-life of ostrich muscles negatively. South African Journal of Animal Science Vol. 36(3) 2006: 197-20

The effect of rumen inert fat supplementation and protein degradability in starter and finishing diets on veal calf performance

Thirty six Holstein bull calves were divided into six groups to determine the effect of protein degradability and rumen inert fat supplementation in starter and finishing diets on nutrient digestibility and veal production. Calves received low (LD) or high (HD) degradable protein diets, with or without rumen inert fat supplementation. Two commercial fat sources were used, Morlac (mlc) and Golden Flake (gf), included in the experimental diets at 2.5% of dry matter (DM). A commercial milk replacer was fed to all calves at 4 L/day for 42 days, followed by 2 L/day until weaning at 49 days of age. Starter diets were offered ad lib. from day 14 to 10 weeks of age and finishing diets ad lib. from 11 to 20 weeks of age. All calves were slaughtered at 20 weeks to determine carcass weight and dressing percentage. There were no significant differences in body weight gain or dry matter intake over the entire 20 week period. Feed conversion ratio (FCR) was improved when fat was supplemented to LD, but not to HD diets. The FCR (DM intake/kg gain) of LD, HD, LDmlc, HDmlc, LDgf and HDgf diets was 3.45, 3.44, 3.07, 3.81, 3.02 and 3.43, respectively. All 36 calves were used in a digestibility trial during week 18 of the study, using chromium oxide as a marker. Apparent digestibility values (%) for LD, HD, LDmlc, HDmlc, LDgf and HDgf, respectively, were 61.7, 65.9, 75.4, 69.0, 75.5 and 67.2 for DM, 61.4, 61.6, 71.3, 68.2, 75.4 and 66.1 for crude protein and 58.6, 66.5, 76.0, 70.9, 78.4 and 70.8 for fat. Dry matter and fat digestibilities were significantly higher when fat was added to LD diets, but not to HD diets. The CP digestibility was significantly higher when fat was added to either the LD or the HD diets. It was concluded that rumen inert fat supplementation to calf diets appears to improve feed conversion ratio and DM and fat digestibilities, but only when added to low degradable protein diets and only after 10 weeks of age. Crude protein digestibility appears to improve with fat supplementation to either high or low degradable protein diets. Keywords: Calves, Nutrition, Fat supplementation, Protein degradability, Nutrient digestibility, Veal production South African Journal of Animal Science Vol.33(4) 2003: 257-26

Effects of post mortem temperature on rigor tension, shortening and pH in ostrich muscle

Fully developed rigor mortis in muscle is characterised by maximum loss of extensibility. The course of post mortem changes in ostrich muscle was studied by following isometric tension, shortening and change in pH during the first 24 h post mortem within muscle strips from the muscularis gastrocnemius, pars interna at constant temperatures of 7 °C and 37 °C. Maximum shortening was significantly higher at 37 °C (33.4 ± 3.57%) than at 7 °C (10.7 ± 2.63%). The rate of rigor development was temperature dependent, reaching a maximum tension at 4.08 ± 3.89 h post mortem in muscle strips at 37 °C; while at 7 °C maximum tension was reached at 10.5 ± 6.47 h post mortem. It was concluded that the completion of rigor occurred at the point of minimum pH. Keywords: Rigor mortis, rigor tension, muscle shortening, ostrich, rigor shortening, cold-shortening, hot-deboning, rate of pH declineSouth African Journal of Animal Science Vol. 38 (3) 2008: pp. 184-19

A comparison between the body composition, carcass characteristics and retail cuts of South African Mutton Merino and Dormer sheepe/pj

No Abstract. South African Journal of Animal Science Vol. 34 (1) 2004: pp.44-5

Production of five Merino type lines in a terminal crossbreeding system with Dormer or Suffolk sires

This study details the production performance of ewes and lambs that originated from a terminal crossbreeding experiment that involved five Merino type dam lines and two terminal crossbreeding sire lines from 1999 to 2002. Ewe 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 rate (Rep+). Dormer and Suffolk rams were used as sire breeds on these ewes. Data include 777 birth and 605 weaning records of lambs and 562 production year records of ewes. At birth the progeny of SAMM ewes were heavier than those of the other ewe lines, while FW+ ewes produced smaller lambs at birth than SAMM cross and Rep+ ewes. Lamb survival was not significantly affected by ewe line or sire breed. The progeny of the dual-purpose ewe lines (SAMM, SAMM cross and Dohne Merino) were heavier than those of Merino ewes (FW+ and Rep+) at weaning. No sire breed difference was found for birth or weaning weight. The joining weights of dual-purpose ewe lines were higher than those of Merinos. Although considerable variation was found between ewe lines in terms of lamb output (number or weight of lamb weaned per ewe joined), the only significant difference was for weight of lamb weaned between SAMM cross and FW+ Merino ewes. Means for weight of lamb weaned per joining (in kg) were 37.3 for SAMM ewes, 39.6 for SAMM cross ewes, 35.5 for Dohne Merino ewes, 28.9 for FW+ ewes and 34.6 for Rep+ ewes. No differences in ewe reproduction were found between ewes joined to Dormer or Suffolk rams. The clean wool production of SAMM ewes amounted to 46% of that recorded in FW+ ewes. Corresponding percentages were 68% for SAMM cross ewes, 74% for Dohne Merino ewes and 90% for Rep+ ewes. The wool of SAMM ewes was slightly coarser in diameter than those of SAMM cross and FW+ ewes, which in turn was coarser than those of Rep+ and Dohne Merino ewes. The economic viability of crossbreeding programs involving the respective ewe lines would depend on the ratio between the prices of wool and lamb. No conclusive advantage could be demonstrated in favour of any of the sire breeds. Keywords: Fibre diameter, Lamb growth, Lamb output, Reproduction, South African sheep breeds, Wool yield South African Journal of Animal Science Vol.33(4) 2003: 223-23

The growth and carcass and meat characteristics of pigs raised in a free-range or conventional housing system

The growth performance and the carcass and physical and chemical characteristics of the meat of 24 Landrace X Large White pigs were compared when reared under a free-range or a conventional housing system. The free-range pigs had lower feed intakes and slower growth rates than the conventionally housed pigs. The free-range pigs also had a lower P2 fat depth and therefore yielded a carcass with a higher percentage lean meat. Housing systems had no effect on the weight distribution of the commercial cuts (as a percentage of cold carcass weight). The meat from the free-range pigs was slightly more reddish in colour, but apart from that housing systems had no effect on the water-holding capacity (WHC) of the meat, its initial pH (pH45) or its final pH (pH24). The meat from the free-range pigs had the same shear force (WBS) values as those of the conventionally housed pigs. Housing systems had an influence on the fatty acid composition. Stearic acid (C18:0) was significantly lower in the meat of the free-range pigs than that of the conventionally housed pigs while linoleic acid (C18:2n-6) and polyunsaturated fatty acid (PUFA) concentrations were significantly higher. However, the moisture, fat, protein and ash contents as well as the mineral composition in the meat were unaffected by housing systems. It could be concluded that pigs raised in a conventional housing system produced meat with similar quality characteristics to that of pigs raised in a free-range housing system. Keywords: Free-range, Housing systems, Growth performance, Carcass yield, Physical quality, Chemical composition South African Journal of Animal Science Vol.33(3) 2003:166-17

Genetic variation in nodule size at different sites on the skins of slaughter ostriches

Nodule size is an important indicator of leather quality in the ostrich leather trade. The present study investigated genetic variation in nodule size at five sites on the skin, namely the neck, back, upper leg, flank and butt. Nodule size increased with an increased chronological age at all sites. Estimates of h² for nodule size ranged from 0.09 ± 0.07 on the flank region to 0.24 ± 0.10 on the upper leg region. Genetic correlations between nodule sizes measured at different sites were generally lower than expected, linked to high standard errors and, mostly not significant. These preliminary results seem to suggest that nodule size on different locations of the skin is not necessarily the same genetic trait. Apart from the limitations evident from these results, the objective measurement of nodules on ostrich skins is tedious when done manually, with little prospect for automation. The number of nodules per dm² (nodule density) was considered within skin sites as an indirect criterion for the improvement of nodule size. However, genetic correlations between nodule density and nodule size were negative, variable in size and generally not significantly different from zero or unity. Based on these preliminary results, alternative strategies for the genetic improvement of ostrich skin nodule size should be considered. South African Journal of Animal Science Vol. 36(3) 2006: 160-16