Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 46 num. 2 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Effects of whey, molasses and exogenous enzymes on the ensiling characteristics, nutrient composition and aerobic stability of maize cobs</b>]]> The study was conducted to assess the effects of whey, molasses and exogenous enzymes on fermentation, aerobic stability and nutrient composition of ensiled maize cobs. Five treatments were ensiled in 1.5 L anaerobic glass jars over 32 days, namely i) control (maize cobs without additives (CON); ii) maize cobs with sugarcane molasses only (MOL); iii) MOL and whey (MOW); iv) MOW and exogenous enzyme at 0.5 g/kg maize cob mixture (ENZ1) and v) MOW and exogenous enzyme at 1 g/kg maize cob mixture (ENZ2). There was a day effect on gross energy (GE) for CON, MOL, ENZ1 and ENZ2 and none for MOW. There was a day effect in ADF for MOL, ENZ1 and ENZ2 and none for CON and MOW. There was lower dry matter (DM) on day 32 compared with day 0 for all treatments. There were treatment effects for GE, crude protein (CP), ash, ether extract, amylase-treated neutral detergent fibre and acid detergent fibre (ADF). On day 32, the neutral detergent fibre (NDF) and ADF concentrations in CON were higher than in MOL, MOW and ENZ2. At day 32, CON silage pH (4.2) was lower than the pH values of ENZ1 (4.5) and ENZ2 (4.6) silages. Acetic acid levels were higher in ENZ1 than ENZ2 silages. Ammonia nitrogen (NH3-N) levels averaged 25 ± 6.6 g NH3-N/kg total nitrogen, which is indicative of satisfactory ensiling. The MOL, ENZ1 and ENZ2 silages produced more carbon dioxide than CON and MOW silages. The addition of molasses and whey did not improve the nutritive quality of the maize cobs after ensiling. Ensiling maize cobs with molasses, whey and exogenous enzymes resulted in lower DM and fibre levels in the maize cobs, which could enhance intake and digestibility of nutrients when offered to pigs as a component of a balanced diet. Further investigations using higher concentrations of whey and molasses are warranted to improve the energy and protein composition of the maize cobs. <![CDATA[<b>Fermentation products of <i>Cordyceps militaris </i>enhance performance and modulate immune response of weaned piglets</b>]]> The aim of this study was to investigate the effect of supplementation of Cordyceps militaris fermentation products (CMF) on growth performance and immunocompetence of piglets. The study involved three groups of animals, which were supplemented with CMF (500, 1000 and 1500 μg/kg feed), and a control group. CMF supplementation significantly increased growth performance in weaned piglets. Bodyweight gain, average daily gain and feed intake in animals supplemented with 1000 μg CMF/kg feed were significantly higher in comparison with the control group. In addition, CMF supplementation only significantly increased the synthesis of Th1 cytokines, as indicated by the levels of IL-2 and IFN-γ. The piglets fed with the CMF supplement displayed an increased cellular immune response. Indeed, alveolar macrophages isolated from piglets supplemented with 1000 and 1500 μg CMF/kg feed had significantly higher chemotactic and phagocytic indices than those isolated from piglets that received the control feed or feed supplemented with 500 μg CMF/kg. In relation to the absence of effect on Th2 cytokines, the CMF supplement had no effect on hog cholera antibody titre. In summary, feed supplementation with CMF improves growth performance and enhances cell-mediated immunity. CMF supplementation may thus be useful at weaning to counteract physiological and immunological stress during this period. <![CDATA[<b>Effects of bacterial inoculation on the fermentation characteristics and aerobic stability of ensiled whole plant soybeans <i>(Glycine max </i>(L.) Merr.)</b>]]> The effect of bacterial inoculation on the fermentation and aerobic stability of two ensiled whole plant soybean (WPSB) cultivars was determined in a 2 x 2 factorial design. Two WPSB cultivars, Link LF6466 and Pannar 522 RR, were harvested at their R6 growth stage, chopped to 25 mm and ensiled in 1.5 L anaerobic jars. The chopped forages were treated with or without the bacterial inoculant Lalsil Dry (LD) and treatments were as follows: i) Pan control (soybean cv Pannar 522 RR with no additive); ii) Link control (soybean cv Link LF 6466 with no additive); iii) Pan LD (soybean cv Pannar 522 RR treated with LD); and iv) Link LD (soybean cv Link LF 6466 treated with LD). Jars were opened on days 3, 7, 10, 21 and 90 to determine pH. Samples of day 0 and day 90 were used to determine chemical composition and fermentation characteristics. In addition, samples of day 90 were subjected to an aerobic stability test in which they were exposed to air for five days, and CO2, pH, hours for temperature to rise above 2 °C, yeasts and moulds were determined. Pannar cultivar had higher contents of dry matter (DM), crude protein (CP), gross energy (GE) and ether extract (EE) compared with the Link cultivar at pre-ensiling. However, Link cultivar had higher content of water-soluble carbohydrates (WSC) compared with Pannar. Inoculation with LD reduced silage DM, CP and fibre contents, and increased silage pH compared with the control. Inoculation increased silage acetic and propionic acids, but had a lower content of lactic acid (LA) and DM recovery compared with the control. When compared with the control, silage aerobic stability was improved with LD inoculation, as indicated by reduced CO2 production, and yeast and mould populations, and increased number of hours for stability after aerobic exposure. It was concluded that LD inoculant reduced silage fermentation and preservation, but improved aerobic stability of silage. Further work is needed to determine the effects of soybean silage on growth performance and production response of ruminants. <![CDATA[<b>Fatty acids, lipid and protein oxidation, metmyoglobin reducing activity and sensory attributes of <i>biceps femoris </i>muscle in goats fed a canola and palm oil blend</b>]]> The link between the consumption of saturated fatty acids of ruminant meat and the incidence of chronic diseases in humans substantiates efforts to modify its lipid profile. However, altering the lipid profile of ruminant meat could affect its quality attributes and shelf life. This study investigated the effect of a blend of 80% canola oil and 20% palm oil (BCPO) and post mortem ageing on lipid composition, antioxidant status, colour, metmyoglobin reducing activity (MRA) and lipid and protein oxidation in biceps femoris muscle in goats. Twenty-four bucks were randomly assigned to diets containing on a dry matter basis, 0%, 4% or 8% BCPO, fed for 100 d, and slaughtered. The biceps femoris was subjected to 7 d post mortem ageing (4 °C). Neither diet nor post mortem ageing altered catalase, superoxide dismutase and glutathione peroxidase activities or sensory attributes of the biceps femoris. Dietary BCPO improved α- and γ-tocopherol, but did not affect total carotenoids and δ-tocopherol, colour, metmyoglobin content, MRA, TBARS, carbonyl content and free thiol content. Goats fed 4% BCPO had higher cis-9 trans-11 CLA, while those fed 8% BCPO had higher C18:3n-3 and C20:5n-3 compared with other treatments. The 4% and 8% BCPO meat had lower C14:0, but higher C18:1n-9 and C22:5n-3 than the control goats. Post mortem ageing decreased muscle polyunsaturated fatty acids (PUFA), antioxidant compounds, redness, MRA and oxidative stability of lipid and proteins, but increased metmyoglobin content. Dietary BCPO enhanced beneficial muscle lipids without compromising the sensory quality, and lipid and protein stability of the goat meat. <![CDATA[<b>Effects of dietary inclusion of probiotics, prebiotics and synbiotics on intestinal histological changes in challenged broiler chickens</b>]]> The present study aimed at evaluating the effects of probiotics, prebiotics and their combination on intestinal histological changes in broiler chickens challenged with Clostridium perfringens. Two hundred and forty newly hatched male broilers (Ross 308) were equally distributed into six treatments: negative control group: unsupplemented unchallenged birds; positive control group: unsupplemented challenged birds; neoxyval-fed group: 0.5 g/kg diet (antibiotic) challenged birds; GalliPro-fed group: 0.6 g/kg diet (probiotic), challenged birds; TechnoMos-fed group: 0.75 g/kg diet (prebiotic), challenged birds; and synbiotic-fed group: birds challenged by C. Perfringens (4 x 10(8) CFU /mL). At 35 days old, samples from the ileum and jejunum were collected for histological measurements (height, width and villus surface area), and histopathological changes were assessed. The results showed that the length and surface area of villi in the ileum and jejunum were lower in the positive control, whereas length and surface area of villi in the ileum and jejunum of all feed additive treatments were higher, compared with the positive control and antibiotics. Necrotic enteritis (NE) development was evident in the positive control group. Signs of necrosis of the mucosal membranes, haemorrhage and fibrosis with depletions of gut associated lymph follicle (GALF) in submucosal layer were very clear. Pathological changes improved in all feed additives, except for the antibiotics. These results indicated that alternatives to antibiotics could be used to improve the length and surface area of a villus and the health of the animal by suppressing C. perfringens. <![CDATA[<b>Effects of temperature, heating time and particle size on values of rumen undegradable protein of roasted soybean</b>]]> Roasted soybeans are commonly used in diets for dairy cows, but the processing conditions of roasted soybean and their effects on rumen undegradable protein (RUP) have not been fully understood. In this study, the effect of the processing of roasted soybean on RUP was examined through a factorial arrangement of treatments. The effects of roasting temperature (115 °C, 130 °C and 145 °C), time of roasting (5, 10 and 15 min) and particle size of soybean (whole, coarse and fine) on the protein fractions of roasted soybean were analysed with the Cornell Net Carbohydrate and Protein System (CNCPS) and protein dispersibility index (PDI) methods. The whole, coarsely ground and finely ground soybean had mean particle sizes of 5.30 mm, 1.15 mm and 1.05 mm. The proportion of soluble protein was reduced with increasing temperature and time of roasting. The true protein with intermediate rates of degradation decreased with escalating temperatures, but increased when the time was raised and the particle size reduced. Also, the true protein level with slow rates of degradation was raised with increasing temperature and heating time, but reduced when decreasing the particle size. The undegradable true protein level, on the other hand, was increased by decreasing the particle size. The results of CNCPS and PDI revealed that the recommended method would be to use soybeans with a particle size of 1.15 mm, and to roast them at 115 °C for 10 minutes. Furthermore, the results showed that different methods of processing used in soybean roasting could strongly affect RUP content. <![CDATA[<b>Determining the frequencies of B1, B2, B3 and E alleles of the <i>CSN1S1 </i>gene and their effects on milk yield and composition in Saanen goats</b>]]> The aim of the study was to determine the frequencies of B1, B2, B3 and E alleles of the CSN1S1 gene and their effects on milk yield and composition in the Saanen goat breed. Milk samples were collected to identify milk composition with Fourier transform infrared (FTIR) spectroscopy. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to characterize the alleles of CSN1S1 gene. The allelic frequencies of the B1, B2, B3 and E alleles were 0.927, 0.073, 0.390, and 0.272, respectively. B1 and B2 alleles did not affect milk yield and composition. B3 allele had significant effects on protein, fat, total solid (TS), solid not fat (SNF), casein and lactose percentages, but not on lactose yield. E allele significantly influenced fat and TS percentages of milk in the Saanen goat breed. The protein (3.58%), fat (3.83%), TS (12.06%), SNF (8.60%) and casein percentages (2.80%) were higher in B3/B3 goats than in B3/NB3 (NB3: non-B3) and NB3/NB3 goats. For E allele, NE/NE (NE: non-E) goats displayed higher fat (4.06%) and TS (12.42%) percentages of milk than their E/E and E/NE counterparts. As a result, the potential for improving milk composition by selecting for B3 and E allele may be significant in Saanen goats. <![CDATA[<b>Assessment of heavy metal contamination in raw milk for human consumption</b>]]> The presence of heavy metals in various farm inputs, including feed, fertilizer, water and environment leads to excretion of the residues in animals' milk. Because consumption of milk contaminated with heavy metals poses serious threats to consumers' health, a study was conducted in 2012 - 2013 in Pakistan to evaluate the concentration of heavy metals in unprocessed raw milk procured in different seasons from Jhang city, Punjab, Pakistan. A total of 400 milk samples was collected from milk shops and dairy farms, and the contents of heavy metals, i.e. copper (Cu), lead (Pb), cadmium (Cd) and chromium (Cr) were analysed via atomic absorption spectrometry. Results indicated that the average concentrations of Cu, Pb and Cd were significantly higher than International Dairy Federation Standards. Within a season, heavy metal levels differed significantly among samples. For each type of milk source, there was a significant difference in mean concentration of heavy metals between summer and winter. Based on these findings, there is a critical need to set legal limits and surveillance for heavy metals in an animal's milk. <![CDATA[<b>Population structure and genetic trends for indigenous African beef cattle breeds in South Africa</b>]]> The aim of this study was to investigate population structure and genetic trends based on pedigree and performance records of five indigenous African beef cattle breeds (Afrikaner, Boran, Drakensberger, Nguni and Tuli) in South Africa. Pedigree completeness over six generations was higher than 88.5% in the first generation for all breeds, except for the Boran, which was introduced to South Africa only recently. The average generation interval ranged between 6.0 and 6.4 years. The rates of inbreeding per generation varied between 0.18% and 0.52%, while the effective population sizes ranged between 89 and 364. This is sufficient to maintain the genetic diversity within all of these populations. Inbreeding and effective population size for the Boran breed could not be accurately estimated, because it was introduced into South Africa only recently. Estimated breeding values for growth traits and scrotal circumference were also included for analyses to determine genetic trends of the same five breeds. Breeding values were regressed on birth year from 1986 to 2012. Genetic progress has been made in weaning and post weaning weights for all the breeds. This study has confirmed the benefits of having sufficient pedigree and performance data available for genetic evaluations and application in selection for genetic improvement.