Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 49 num. 6 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Bromide: A potential risk to livestock production in South Africa</b>]]> Bromide (Br-) concentrations (mg/L) in groundwater range from no observed adverse effect levels (NOAEL), which is considered safe, and increase to constituent of concern (COC) when the concentrations approach the recommended maximum levels for safety, and to potentially hazardous chemical constituent when the concentrations exceed the recommended safe levels. The default recommended NOAEL of less than or equal to 0.01 mg/L was validated with the highly sensitive chicken embryo model. Chronic and acute exposure to Br- in groundwater can induce negative consequences, which include hypothyroidism, reduced production and Br- accumulation in organs and secretion in milk, depending on the type of livestock and their physiological state, and potential interactions with environmental factors. Bromide competes with chloride (Cl-) and infiltrates the Cl- space, has a relatively long half-life in proportion to the ingestion rate, and a low renal clearance rate of approximately 5% of ingestion, leading to an accumulation in the body. The most vulnerable livestock are neonatal and suckling animals, those with a high water intake, such as during lactation, or in an adverse environment, and because of chronic exposure. The recommendation is to include Br- in chemical analysis of water quality and to assess the potential risk to livestock. <![CDATA[<b>Effects of pasture type and level of concentrate supplementation on quality and fatty acid profile of lamb meat</b>]]> Objectives of this study were to evaluate effects of grazing tropical forage species and level of supplementation with grain on characteristics of lamb meat. Ninety-day-old lambs (n = 36) (22.54 ┬▒ 2.72 kg) were randomly assigned to a 2 x 3 factorial arrangement of pasture types (Aruana and Marandu) and levels of concentrate supplementation (0%, 1.5% and 3% of bodyweight). Water retention capacity, shear force, weight loss after cooking, pH, colour, and intramuscular lipid content of the meat were evaluated. A panel of 145 consumers evaluated the appearance, flavour, fat flavour, odour, and softness of the meat and provided an overall assessment. Supplementation at 3% of bodyweight reduced the luminosity of the meat. The appearance of meat from lambs that grazed Aruana grass was deemed preferable to that of meat from lambs that grazed Marandu grass. Total branched-chain fatty acids (BCFAs) were increased when grazing Marandu grass compared to Aruana grass. Lambs supplemented with concentrate had reduced BCFA/kg of meat and its content of both monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids were increased. Supplementation with concentrate at 1.5% and 3.0% of bodyweight increased n-6 PUFAs by 16.8% and 90.0%, decreased n-3 PUFAs by 49.7% and 35.9%, and thus increased the n-6/n-3 ratio by 135.0% and 183.8%, respectively. Lambs that were finished on grass without supplementation had a more healthful fatty acid profile and received better scores for flavour and global appreciation. To improve the quality of fatty acids in the meat, the pasture system is recommended. <![CDATA[<b>Microbial additives affect silage quality and ruminal dry matter degradability of avocado <i>(Persia Americana) </i>pulp silage</b>]]> This study evaluated effects of microbial inoculation on fermentation, aerobic stability and ruminal dry matter (DM) degradation of silage produced from Avocado (Persia Americana) pulp (AP). The AP, 800 g/kg fresh matter (FM) was mixed with 150 g grape pumice (GP)/kg FM and 50 g sugarcane molasses/kg FM. The mixture was treated with 1) no inoculant (control), 2) Emsilage inoculant (EMS), and 3) Sil-All 4x4 W.S. inoculant (SIL). Materials were ensiled in 1.5 L anaerobic jars for 90 days. Triplicate samples were collected on days 0, 3, 7, 10, and 90 for determination of fermentation, nutritive value and aerobic stability. In situ DM degradability was determined using 3 rumen cannulated Holstein cows. Microbial inoculation to AP silage increased lactic acid bacteria population, which subsequently increased residual fermentation substrate and lactic acid content. Terminal pH and volatile fatty acids of the silage were not affected by inoculation. Inoculated silage had less fibre and reduced aerobic stability compared to the control. The AP and its mixture had higher DM soluble fractions compared to the GP which had a higher degradation rate. Potential degradable fraction and extent of degradation were similar for each treatment. The EMS treatment had higher soluble fractions and lower degradation rate than other treatments. Inoculation with SIL improved degradation of the silage compared to other treatments. Thus, microbial inoculation qualifies the AP silage as a potential feed for ruminants. <![CDATA[<b>Effects of Lavender <i>(Lavandula angustifolia) </i>augmentation of alfalfa silages</b>]]> The aim of this study was to determine the chemical, fermentation, and microbiological properties of alfalfa silages that were augmented with lavender (Lavandula angustifolia) and to appraise their in vitro organic matter digestibility (IVOMD), metabolizable energy (ME), and net energy for lactation (NEL) contents. Lavender flowers were added to alfalfa silages at 0.5, 1.0, 1.5, and 2.0% of the weight of alfalfa. An unaugmented alfalfa silage was also evaluated. After 75 day of ensiling, pH, dry matter, NDF and ADF contents of alfalfa silages had decreased and OMD had increased with the addition of lavender. No significant differences in crude protein, ash, ether extract, lactic acid, acetic acid, propionic acid, lactic acid bacteria number, ME and NEL contents were detected. No butyric acid, Enterobacteriaceae, Listeria spp, sulphide reducing anaerobes, and yeasts were found in the alfalfa silages. Mould content decreased with the addition of lavender. Thus, the addition of lavender flowers to alfalfa silages may improve their quality. <![CDATA[<b>Effect of controlled breeding on performance of beef cattle in Central Bushveld bioregion</b>]]> In most extensive beef production systems in South Africa, calves are weaned at specific dates. This implies that cows that calve late in the season wean younger and lighter calves. In the current study, Bonsmara cows were mated naturally after synchronization over six years (2009 - 2014) in an extensive production system on natural veld in the Central Bushveld bioregion. Within the herd, 50% of cows were synchronized prior to the commencement of the summer breeding season and they were mated naturally for 90 days. The results indicated that calving rate did not differ significantly between cows that were synchronized and non- synchronized. However, there was a significant difference between years in calving rate. Oestrous synchronization prior to natural breeding influenced the average days to conception. The difference in percentage of cows that calved within 293 days of the onset of the breeding season between those that were oestrous synchronized and non-synchronized was 15% in favour of the synchronized cows. Although calves from synchronized cows achieved higher average weaning weights, the cost implications of synchronization offset the benefit of higher calf weights. <![CDATA[<b>Genetic diversity and differentiation among Korean-Holstein, Hanwoo, and Uganda-Holstein breeds</b>]]> The aim of this research was to assess genetic diversity of Korean-Holstein, Korean Hanwoo, and Ugandan-Holstein dairy cattle. DNA was extracted from either blood or hair of Korean-Holstein (n=74), Korean-Hanwoo (n=75) and Ugandan-Holstein (N=77) using AccuPrep┬« PCR purification kit. The DNA samples were amplified by multiplex polymerase chain reaction, using GeneTrack M Hanwoo genotyping kit and assayed using ABI genetic analyser 3130XL. Number of alleles, expected heterozygosity (He), observed heterozygosity (Ho), and the polymorphism information content (PIC) were estimated from 10 microsatellite loci in the three breeds. In addition, F-statistics for each of the 10 microsatellites in the three cattle breeds were estimated using fstat version computer program. GENETIX (v.4.02) was used to perform factorial correspondence analysis (FCA) from the allele frequencies and multi-locus clustering was done using STRUCTURE analyses. A total of 124 alleles were detected. The number of alleles per locus varied from eight (TGLA126) to 22 (TGLA122), with an overall mean of 12.2. Expected heterozygosity ranged from 0.617 (SPS115) to 0.854 (TGLA53) and averaged 0.761. Observed heterozygosity ranged from 0.6 (SPS115) to 0.859 (TGLA53); and averaged 0.761. The mean PIC was 0.723; and means of the F-statistics FIT, FST and FIS were 0.077, 0.076 and 0.001 respectively. Although FCA revealed clear differentiation of Uganda-Holstein, Korean-Holstein, and Hanwoo, clustering assignments showed genetic admixture between Ugandan dairy cattle (Uganda-Holstein) and Hanwoo. In conclusion, the allelic variation present at the 10 loci was sufficient to categorize these cattle into distinct breed groups. <![CDATA[<b>Carryover effects of varying hay concentration on the transition to silage-based feeding of weaned dairy calves</b>]]> Objectives of the experiment were to determine effects of dietary hay concentration in a dry total mixed ration and its carryover effects on intake, growth performance, faecal score, and feed efficiency of weaned dairy calves. Eighteen Friesian χ Jersey weaned calves (n = 6 calves/treatment) were randomly assigned to three rhodes grass hay treatments (RG13, RG26, and RG39). The experimental diets were rhodes grass hay-based total mixed rations containing 13%, 26%, and 39% chopped hay on a DM basis. The experiment had two phases of four weeks each. In phase 1 (weeks 1-4), weaned calves were fed RG13, RG26, or RG39. Then, in phase 2 (weeks 5-8), all calves were shifted to a maize silage-based diet. All the diets were iso-nitrogenous and were fed ad libitum. Calves were housed in individual pens and had free access to water and feed. Average daily gain and daily dry matter intake were analysed as repeated measures, whereas bodyweight and feed efficiency were analysed using one-way ANOVA. In phases 1 and 2 dry matter intakes were similar. Growth rate decreased linearly with increasing concentration of hay in phase 1. Overall, daily dry matter intake, average daily gain, change in body condition score and structural measurements were not affected by dietary treatments. However, overall feed efficiency was improved for calves fed RG26 compared with RG13 and RG39. Thus, feeding a moderate level of hay had positive impacts on the transition to a silage-based TMR.