Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 42 num. 4 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Physical and chemical properties of selected beef muscles infused with a phosphate and lactate blend</b>]]> The consumer demands a beef product of consistent and acceptable tenderness. The infusion of beef muscles with a blend containing sodium and potassium salts, various phosphates and lactates has the potential to improve the current status of low meat consumption and inconsistent tenderness of fresh beef products in South Africa. In the present investigation, the biceps femoris (BF, silverside), rectus femoris muscle (RF), semitendinosus muscle (ST, eye of the silverside), supraspinatus muscle (SS, scotch fillet) and longissimus et lumborum muscles from the left side of beef carcasses were infused, 3 d post mortem, with a blend consisting of various sodium and potassium salts, di- and triphosphates and lactates, while the corresponding muscles from the right side were untreated and served as the control. The changes in beef quality over a 19-d period and the initial proximate and mineral composition of the muscles were also determined. The general findings suggest that an increase in tenderness concurrent with an acceptable beef colour resulted from the infusion with this blend. The chemical composition of the treated muscles was not negatively affected by the infusion and the mineral content of the treated muscles was increased, accordingly. <![CDATA[<b>Effect of RRR-α-tocopherol succinate on the meat quality and antioxidative status in broilers</b>]]> The objective of this study was to compare the effects of two esters of α-tocopherol, all-rac-α-tocopherol acetate (DL-a-TOA) and RRR-a-tocopherol succinate (D-α-TOS), on meat quality and the antioxidative status in chicks. A total of 320 day-old Arbor Acres broiler chicks were randomly allocated to 4 treatments, each consisting of 8 pens of 10 chicks per pen. Birds in the control group received the basal diet supplemented with 30 mg DL-a-TOA/kg diet. In the other treatments the diet was supplemented with D-a-TOS at 15 mg/kg, 30 mg/kg or 60 mg/kg (TOS1, TOS2 and TOS3 treatments), respectively. The trial lasted 42 days. Positive correlations existed between dietary D-a-TOS levels and plasma and hepatic α-tocopherol concentrations, and a negative correlation with malonaldehyde (MDA) concentrations. In comparison with the control group, 30 mg/kg and 60 mg/kg of dietary D-a-TOS supplementation resulted in an increase in glutathione peroxidase (GSH-Px) activity and glutathione (GSH) content of the breast and thigh muscle and total superoxide dismutase (T-SOD) activity in the thigh muscle. Furthermore, the muscle MDA and hepatic reactive oxygen species (ROS) levels were reduced. As for meat quality, 48 h drip loss and shear force of breast and leg muscle were lower in broilers in the TOS1, TOS2 treatments and also the cooking loss in leg muscle. The study suggests that 30 mg/kg to 60 mg D-a-TOS/kg of the diet could enhance the antioxidant capacity of broiler meat, and its water-holding capacity and tenderness, in association with the reduction in lipid peroxidation as measured as a decrease in MDA and ROS concentrations. <![CDATA[<b>Effects of feeding the seeds of <i>Prosopis laevigata, Acacia schaffneri</i> and <i>Ceratonia siliqua</i> on the performance of broiler chicks</b>]]> The aim of the present study was to assess the nutrient contents and potential feeding value in the diet of broiler chicks of the seed of three tree species, mesquite (Prosopis laevigata), Schaffneri's wattle (Acacia schaffneri) and the carob tree (Ceratonia siliqua). The dry matter (DM), ash, crude protein (CP), amino acid and fatty acid concentrations of the seeds were determined. Growth performance was measured in terms of weight gain, feed intake and feed conversion ratio. Sixty-four day-old Cobb broiler chicks were randomly assigned to the following treatments: control diet; control + P. laevigata; control + A. schaffneri and control + C. siliqua. The diets were formulated to contain 200 - 210 g CP/kg and 13.39 MJ ME/kg, with approximately 60 g CP/kg diet originating from the respective seeds. Prosopis laevigata contained the highest protein level (394 g/kg DM), followed by A. schaffneri (229 g/kg DM) and C. siliqua (183 g/kg DM). The concentration of linoleic acid in the fat was found to be the highest in all three species, followed by oleic acid. The methionine concentration in the seed of the three species was low compared with that in soybean meal. Weight gain and feed intake of the chicks were significantly higher in the control diet and there were no significant differences between P. laevigata and A. schaffneri. Chicks receiving C. siliqua had the lowest weight gain. Feed conversion ratio was the lowest in the control diet, with no significant differences between the P. laevigata and A. schaffneri treatments, while C. siliqua had the highest feed conversion ratio. It is concluded that the seeds of the two species, P. laevigata and A. schaffneri, could partially replace commercial feed ingredients as protein and energy sources in diets of poultry kept under subsistence farming conditions in rural areas of Mexico. <![CDATA[<b>Chemical composition, fatty acid profile and colour of broiler meat as affected by organic and conventional rearing systems</b>]]> The major quality characteristics of breast and thigh meat, including chemical composition, fatty acid composition, cholesterol content and colour of slow-growing broilers (Hubbard Red-JA), reared under either organic or conventional rearing systems, and fast-growing broilers (Ross-308) grown under the conventional procedure, were investigated in this comparative study. Slaughter age was 81 days and 42 days for slow- and fast-growing birds, respectively. A lower protein, but higher fat content was measured in the thigh meat of slow-growing broilers reared both in the organic and conventional systems, compared with conventionally reared fast growers. In both systems the breast meat of fast-growing birds had a higher moisture content than those of the slow-growing birds. The organic system promoted ash retention in breast meat compared with conventional rearing procedures. The fatty acid profile of thigh and breast meat showed different responses to broiler rearing systems. Both thigh and breast meat of conventionally reared slow-growing birds contained higher cholestorel levels. Breast and thigh meat yielded from conventionally reared fast-growing birds had a markedly higher red appearance, but a lower yellow colour, than those of slow growers. The organic system increased the yellowness of the meat. In conclusion, the organic rearing procedure provided no added benefit to chicken meat quality than current conventional applications, except in yellowness. Meat produced from birds in the organic system did not meet consumer expectations of presenting a lower n-3 but a higher n-6/n-3 ratio in thigh meat. <![CDATA[<b>Broiler breeders utilise body lipid as an energy source</b>]]> The study was conducted to determine the extent to which broiler breeder hens could make use of excess body lipid reserves as a means of maintaining laying performance. The experiment was divided into two phases. In the first phase, the birds aged 37 weeks were allocated one of four daily allowances: 160, 175, 190 or 205 g of a commercial broiler breeder feed for a period of four weeks in order to achieve four levels of fatness in the hens. During the second phase, also lasting four weeks, the birds were given a high protein, low energy feed at three rates of allocation (120, 100 or 80 g/hen d). Performance was higher over the final two weeks of Phase 2 when birds were fed 120 g/d in this period, with production tending to decrease as allocations increased in Phase 1, although this was not significant. The same pattern of response was seen in birds given 100 g/d in the second phase of the trial, i.e. excessive lipid reserves tended to be detrimental to performance in these two treatments. However, where 80 g was allocated daily in Phase 2 this was clearly insufficient to sustain performance, but in this case egg production was considerably higher in birds that had been given larger amounts of food in Phase 1, and which could therefore draw on body lipid reserves as a source of energy. Rate of lay increased by 3.5% and egg output by 4.0 g/d for every additional 10 g of food given in Phase 1, as a result of lipid reserves having been utilised when daily food intake was severely depressed. Egg weight was not affected by any of the feed allocations until the last two weeks of the trial when birds fed 80 g/d started laying smaller eggs. Broiler breeders are capable of maintaining their egg production for short periods at an energy intake that is much lower than is recommended and this has implications when modelling the effect of food composition on performance of broiler breeder hens. <![CDATA[<b>Dietary supplementation of mannanoligosaccharides to turkey hens on their growth performance and antioxidant status in the blood</b>]]> The research focused on the effect of a prebiotic additive, mannanoligosaccharides (Bio-Mos), in the diet of turkey hens on their growth performance and measurements of pro-oxidation and antioxidation systems in their blood. The investigation was performed on 240 six-week-old turkey hens of the heavy Big-6 breed, randomly divided into two groups. Group I was the control group, whereas the birds in group II were fed the control diet with a 0.5% addition of Bio-Mos. Bio-Mos did not increase the concentration of lipid peroxidation products, peroxide H2O2 and malone dialdehyde. However, it contributed to the increased concentration of some antioxidation parameters such as vitamin C, iron and zinc in the blood. Moreover, it led to an improved growth performance. The study suggested that mannanoligosaccharides can be used in practice as a dietary additive for turkeys, stimulating the mechanisms of the birds' antioxidation defence and improving their growth performance. <![CDATA[<b>Estimation of genetic and phenotypic parameters for sow productivity traits in South African Large White pigs</b>]]> The objective of the study was to estimate genetic and phenotypic parameters for sow productivity traits of South African Large White pigs, using data from the Integrated Registration and Genetic Information Systems. The analyses were done on 29 719 records for 7 983 sows from 29 herds, which farrowed between 1990 and 2008. Data were analysed as a sow trait using a repeatability animal model. The traits analysed were number of piglets born alive (NBA), litter birth weight (LBWT), 21-day litter size (D21LS) and 21-day litter weight (D21LWT). Estimates of heritability for these traits were 0.07 ± 0.01, 0.11 ± 0.01, 0.03 ± 0.01 and 0.06 ± 0.01, respectively. The respective repeatability estimates for the traits were 0.15 ± 0.01, 0.16 ± 0.01, 0.11 ± 0.01 and 0.12 ± 0.01. Genetic correlations among the traits ranged from 0.32 ± 0.07 between NBA and D21LWT to 0.88 ± 0.04 between NBA and D21LS. The phenotypic correlations ranged from 0.35 ± 0.01 between NBA and D21LWT to 0.75 ± 0.01 between NBA and LBWT. Litter traits at birth were more heritable and repeatable than traits measured at 21 days of age. In general, all traits showed positive genetic and phenotypic trends for the period studied. The heritability of sow productivity traits was low and less repeatable, which suggests that response to selection may be slow and that the performance in the first parity may not always predict future performance. However, because of their economic importance, an attempt should always be made to keep these traits at their optimum. <![CDATA[<b>Dietary <i>Rhus coriaria</i> L. powder reduces the blood cholesterol, VLDL-c and glucose, but increases abdominal fat in broilers</b>]]> In an experiment, 200 one-day-old broiler chickens (Ross 308) were used to investigate the effects of sumac fruit (Rhus coriaria L.) powder (SFP) on performance, plasma concentrations of total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL-c), low density lipoprotein (LDL-c), very low density lipoprotein (VLDL-c) and plasma fasting blood sugar (FBS), as well as proportional abdominal fat. The chicks were divided into four treatment groups with 5 replicates and 10 birds in each. The birds were fed the basal diet (Z-SFP) or diets supplemented with 2.5 g SFP (L-SFP), 5 g SFP (M-SFP) and 10 g SFP (H-SFP) per kg diet. During the whole experimental period the H-SFP birds had a higher feed intake than the Z-SFP and L-SFP birds, though the H-SFP birds had higher feed conversion ratio compared with birds in the other treatments. No significant differences for body weight gain were recorded between the treatments. The M-SFP and H-SFP birds had lower plasma TC and VLDL-c concentrations than the Z-SFP and L-SFP birds. No significant differences between the treatments were indicated for plasma TG, HDL-c and LDL-c concentrations. Moreover the plasma FBS concentration of the H-SFP birds was lower than the birds in treatments Z-SFP and L-SFP, but no significant differences were observed between the other treatments. Furthermore, significant negative correlations were found between SFP supplementation and plasma TC, VLDL-c and FBS concentrations and a significant positive correlation between SFP supplementation and abdominal fat weight. In conclusion, dietary supplementation of SFP reduces the blood TC, VLDL-c and FBS concentrations, which can be related to decreased activity of HMG-CoA reductase and α-amylase activities. The higher abdominal fat weight of the SFP-fed birds is possibly related to changes of energy storage towards fat deposition. <![CDATA[<b>Variety effect on composition, kinetics of fermentation and <i>in vitro</i> digestibility of oat <i>(Avena sativa</i> L.) straw and its neutral detergent fibre</b>]]> Yield, chemical composition, in vitro digestibility and kinetics of fermentation of straw from 18 varieties of oats (Avena sativa L.) were studied. All the straw varieties were grown in three replicates under the same agronomic conditions. Significance differences were observed in the yield of straw (4.4 to 7.5 ton dry matter (DM)/ha) from different varieties. The proportion of seed/straw from these varieties varied from 0.28 to 1.02. Crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) content varied from 24.2 to 48.1, 626 to 708, 437 to 533 and 52.0 to 92.4 g/kg DM, respectively in the straws. In vitro organic matter digestibility (IVOMD) differed among varieties and varied from 400 to 539 g/kg DM. The mean value of digestible organic matter yield (DOM) was 2.34 ton/ha. A significant difference was observed in the potential gas production (A) and lag time (L) among varieties. The fractional rate of gas production (c, /h) ranged from 0.030 to 0.034. The results emphasized that in any evaluation of oat varieties, kinetics of digestion or fermentation should be taken into consideration as well as yield and digestibility.