Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 46 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<b>Genomic study of the mammary gland in bovines acclimated to a tropical environment</b>]]> This study aims at examining the expression of genes on the mammary gland, corresponding to various levels of adaptation or acclimatization to environmental stress. The authors utilized 18 cows from three genetic groups, Holstein Brazil (HB), Gyr (GG) and Gyrolando (GH ), all in the same stage of lactation, and subjected them to the same management conditions. Venous and arterial blood were collected to determine the hormonal profile and blood chemistry. Mammary gland tissue was used for transcriptomic studies. Prolactin and GH plasmatic concentrations were higher in Holstein animals. There were no differences in IGF-1 concentrations among the experimental groups. T3 concentrations were similar among the Holstein and Gyr groups. From the 4608 transcripts in the BLO-Bovine EST (Michigan State University, US) databank that were used in this experiment, 105 differentially expressed genes were identified in at least one of the groups. Among these, the authors highlighted 14 genes that were related to the structure of the mammary gland (CRDGF, CD97, GH, endoglin, LTF, INPP, PTP), to response to thermal stress (Crh_11, v-Fos, Cdc37) and to milk protein (RPL35, κ-casein, β-casein, a-s2-casein). Eight of these were validated through real-time polymerase chain reaction. The HB animals, in comparison with the GH and Gyr groups, presented up-regulated genes associated with epithelium cellular differentiation and proliferation, milk productivity and decreased heat stress tolerance. Gyr animals presented up-regulated transcripts associated with cellular defence, apoptosis processes and increased tolerance to heat stress. The GH group showed intermediary results compared with the other two groups. <![CDATA[<b>Effects of glucose oxidase on the growth performance, serum parameters and faecal microflora of piglets</b>]]> The experiment was conducted to investigate the effects of diets supplemented with glucose oxidase (GOD) on growth performance, serum parameters and faecal microflora of piglets. One hundred and twelve piglets (35 days old) were randomly assigned to two groups (four replicates per group, half male and half female, and 14 piglets per replicate) and fed a diet with or without 100 U GOD per kg, for 35 days. Feeding GOD caused a higher average daily weight gain and feed intake, and lower feed conversion ratio (FCR) of piglets. No significant difference was observed in the reference values of serum biochemical parameters between the groups fed with or without GOD. The contents of triiodothyronine, thyroxine and growth hormone of piglets fed GOD were higher than those of the control. Moreover, GOD supplementation suppressed the concentration of faecal Salmonella. The results showed that supplementation of GOD to diets promoted growth performance, increased the contents of growth and development-related hormones, and improved the faecal microflora of growing piglets. <![CDATA[<b>Ensiling quality of maize as influenced by the addition of wet distillers grains with soluble</b>]]> Wet distillers grains with soluble (WDGS) were blended with whole maize plants on an as-fed basis at 0%, 20%, 30%, and 40% and ensiled in 3 L bottles to evaluate the silage fermentation characteristics and ensiling quality in a complete randomized design. Each treatment was ensiled in 15 mini-silos and three bottles were opened on days 7, 21, 42 and 120. Each treatment was sampled for chemical composition and silage fermentation parameters. There was a steady decrease in dry matter (DM) concentration of silage with increasing WDGS inclusion level over time. Initial pH (at day 0) decreased with increasing level of WDGS inclusion, with 40% WDGS inclusion recording the lowest pH (3.6) at day 120. Lactic acid concentration was slightly lower for WDGS-blended silages compared with the control. In contrast, the acetic acid concentration for WDGS-blended silage increased across all treatments, suggesting a possible diminished effect of clostridium bacteria in the silage owing to a reduced pH. The acid detergent fibre (ADF), neutral detergent fibre (NDF) and IVDOM (in vitro digestible organic matter) did not differ at the time of ensiling among treatments. During post ensiling, ADF increased slightly over time for WDGS-blended treatments (at 120 days). The results from this study indicated that WDGS could be ensiled effectively with maize plants without compromising silage quality. <![CDATA[<b>Age, lighting treatment, feed allocation and feed form influence broiler breeder feeding time</b>]]> During a broiler breeder trial with 3200 Cobb 500 hens, the effects of lighting treatment after 20 weeks' feed allocation and of feed form on the length of time taken to consume the daily allocation of feed were measured. Pullets were reared on 8-hour photoperiods to 20 weeks, then transferred to one of four lighting treatments: permanently to 11 h or 16 hours, transferred temporarily to 11 hours, then given 2-hours increments at 40, 44 and 48 weeks to reach 17 hours or a commercially recommended step-up lighting programme (11 hours at 20 weeks, incrementing by 30 min per week to reach 16 h by 30 weeks). Feed was made available in mash or pelleted form, and hens received 160 g or 180 g by 30 weeks. This allocation was increased linearly from 100 g at 20 weeks. After 40 weeks, the daily feed allocation was reduced by 5 g/bird for each 5% reduction in rate of lay to a minimum of 150 or 160 g/bird. On five occasions, when the hens were 39, 40, 41, 45 and 54 weeks old, the time taken by the hens to consume all their feed was measured and scaled to min/100 g consumed. Hens learned to consume the feed more rapidly as the laying period progressed. The mean clean-up time over all treatments was 67.7, 62.1, 63.4, 47.1 and 40.2 min/100 g at the five ages. Over all treatments and ages, the time taken to consume all their feed was 40.0 min/100 g for birds fed 160 g, versus 72.2 min for those given 180 g of food daily, but this difference was greater at 39 weeks (43.5 versus 91.8) than at 54 weeks (34.0 versus 46.4 min/100 g, respectively). This effect was also evident with feed form, the difference in time taken to consume mash and pellets being greater at 39 weeks (69.2 versus 66.1) than at 54 weeks (54.7 versus 25.7 min/100 g, respectively). The lighting programmes also had an effect on the feed clean-up time. The main effects were 53.5, 56.3, 52.1 and 62.5 min/100 g for the 11-hour constant, 11 to 16 hours, 16-hour constant and step-up programmes, respectively. Significant interactions occurred between treatments. The main reason was the much longer time taken initially by birds receiving the step-up lighting programme and 180 g of pelleted feed to consume all their feed. The effects of these treatments on bird welfare are discussed. <![CDATA[<b>Effects of dietary inclusion of discarded cabbage <i>(Brassica oleracea </i>var. <i>capitata) </i>on the growth performance of South African Dorper lambs</b>]]> A study was conducted to determine the effect of dietary inclusion of discarded cabbage (DC) on the intake and growth performance of lambs. Diets containing 0 (control, DC0), 100 g DC/kg (DC100), 150 g DC/kg (DC150) and 200 g DC/kg (DC200) were fed ad libitum to 36 South African Dorper lambs (22.0 ± 1.3kg live weight). The dry matter intake (DMI) and lamb growth performance was reduced as the level of cabbage in the diet increased. The feed conversion rate of lambs was negatively affected by inclusion of cabbage in the diet. Diets containing cabbage had a lower DM, OM and aNDF digestibility compared with the control. Nitrogen intake and retention was lower in lambs fed diets containing cabbage. Discarded cabbage can be included in finishing diets for lambs but reduced animal performance can be expected. <![CDATA[<b>Effects of dietary oil sources and calcium : Phosphorus levels on growth performance, gut morphology and apparent digestibility of broiler chickens</b>]]> The study investigated the effects of varying dietary calcium (Ca) levels and sources of oil on performance of broiler chickens. A total of 378 one-day-old birds were fed 6% palm oil (PO), soybean oil (SO) or linseed oil (LO) in combination with three levels of Ca, 1%, 1.25% and 1.5%, for six weeks in a 3 x 3 factorial experiment. Birds fed diet supplemented with SO and PO had higher average daily gains, more abdominal fat and greater villi height compared with those fed LO. However, feed efficiency, apparent digestibility of organic matter, ether extract, crude protein and ash were similar across treatments. Regardless of oil source, the chickens fed diets containing 1.5% Ca had a lower bodyweight and apparent digestibility of organic matter, crude protein, ether extract and phosphorus (P) than those fed 1% and 1.25% Ca. In contrast, the birds fed 1.25% Ca had higher ash, Ca and P digestibility than did the 1% Ca birds. Interaction between source of oil and Ca level on mineral digestibility was significant. It can be concluded that palm oil could be used as an alternative to soybean and linseed oils to improve growth performance in broiler chickens. Moreover, increasing the level of Ca to 1.25% can improve broiler performance and apparent nutrient digestibility, regardless of the type of oil used in the current study. <![CDATA[<b>Microsatellite-based estimation of inbreeding level in sheep populations of small effective size</b>]]> In sheep populations with small effective population sizes (Ne), inbreeding is a major concern because genetic variation has to be maintained. A panel of 28 microsatellite markers was used to measure the inbreeding level in three separate Merino flocks bred for superfine wool (CR), low parasite resistance (LR) or high parasite resistance (HR). The Ne was equal to 71.31, 19.19 and 19.48 in the CR, LR and HR flocks, respectively. Inbreeding levels estimated as inbreeding coefficients (FIS) were 0.019, 0.034, and 0.048 in the CR, LR and HR flocks, respectively. These values are quite low, being lowest in CR. This result is in contrast with the known relationship between small Ne and inbreeding level. The reasons could be the management practices in the CR flock of importing sires and restricting the policy of inbreeding by avoiding the mating between relatives. Thus, despite the small Ne and a very limited number of sires being used in every generation, these breeding practices seemed to be effective in avoiding inbreeding. The results reinforce the usefulness of microsatellite markers as a valuable instrument in various genetic aspects of sheep populations. It is suggested that these observations could be implemented with endangered species and breeds with small Ne, thus improving the effectiveness of correct breeding practices, even without direct measuring of genetic variation in populations. <![CDATA[<b>The effects of various dietary vegetable oil sources on villi morphology and liver aldehydes in young layers</b>]]> Twenty-six-week-old laying hens (90 Lohmann Classic Brown) received dietary treatments containing canola and linseed oil at 2% inclusion levels and a control diet for 21 days. The 2% dietary linseed oil, which had higher total polyunsaturated fatty acids (ΣPUFA) and linolenic fatty acid contents, resulted in higher liver malondialdehyde and wider villi than the control group. The 2% canola and linseed oil treatments recorded smaller reproductive organs relative to live weight than the control group. It was concluded that young layers might have an anatomical response to high levels of dietary PUFA, which might improve nutrient absorption and cause a biochemical response, resulting in potentially negative cytotoxic aldehydic lipid peroxidation products. <![CDATA[<b>Production performance of pigs reared in different systems and fed increased energy content diets with or without green alfalfa</b>]]> The objective of this study was to determine the effects of various feeding and housing systems on fattening performance, slaughter value and biochemical serum parameters in growing-finishing pigs. The experimental material comprised 90 growing-finishing pigs, divided into six groups of 15 animals that were diverse in terms of rearing (with or without free access to outdoor runs) and feeding systems (fed increased metabolizable energy (ME) content diets with or without green alfalfa). Different feeding regimes and rearing systems had no significant effects on most fattening results and the carcass traits of the pigs except for daily water and diet intake and feed/gain ratio. Daily water intake was lower in pigs fed complete diets plus green alfalfa forage. Low-density lipoprotein (LDL) cholesterol concentrations were statistically lower in the blood serum of Groups 3 and 6 than in Groups 2 and 4. High-density lipoprotein (HDL) cholesterol levels were significantly higher in the serum of Group 6, compared with other groups. Group 3 had significantly higher triglycerides levels compared with Groups 1, 2, 4, 5 and 6. Taking into consideration all these dependencies, it could be assumed that feeding regime and rearing with access to outdoor runs might improve not only blood lipid profile, but also the dietetic value of pork. It seems that feeding a complete diet with increased ME, plus green alfalfa forage and rearing indoors with free access to outdoor runs, gave the best results. <![CDATA[<b>Effects of oregano essential oil and attapulgite on growth performance, intestinal microbiota and morphometry in broilers</b>]]> Two experiments were conducted to study the effects of a blend of oregano essential oil (OEO) (as a source of natural antibacterial growth-promoting substances) and attapulgite (as a source of toxin-binder and as an antidiarrhoeal agent) on growth performance, intestinal microbiota, and intestinal morphometry in broiler chickens (Ross-308). In the first trial, the control group was fed a basal diet without antibiotic growth promoters, and the experimental group was fed the basal diet supplemented with 5% OEO (OEO) (Ecodiar® powder at 150 g/tn) and 80% attapulgite 80% (Ultrafed® at 6 kg/tn) blend. In the second trial, the experimental group was given the basal diet supplemented with 5% OEO (Ecodiar® powder at 300 g/tn) and 80% attapulgite (Ultrafed® at 3 kg/tn) blend. Intestinal microbiota was enumerated by conventional techniques with selective agar media at the end of the trial at both ileum and caecum, and intestinal morphology was assessed in the duodenum, jejunum and ileum. Results showed that in the first trial, despite the positive impact on daily gain and feed-to-gain ratio, growth performance was not affected by the blend with OEO and attapulgite. Furthermore, no effect was found on intestinal morphometry. However, the counts of lactic acid bacteria were increased significantly, and coliforms were decreased in caecal contents. In the second trial, a positive impact was noticed on daily gain and feed-to-gain ratio by the high OEO and low attapulgite blend. Dietary supplementation of OEO and attapulgite increased ileal villus height and lactic acid bacteria significantly and reduced coliforms in ileal and caecal contents compared with the control group. In conclusion, the combination of OEO at 15 mg/kg and attapulgite at 2.4 g/kg exerted a positive effect on growth performance, ileal villus height and intestinal microbiota of broilers. <![CDATA[<b>Evaluation of the OvineSNP50 chip for use in four South African sheep breeds</b>]]> Relatively rapid and cost-effective genotyping using the OvineSNP50 chip holds great promise for the South African sheep industry and research partners. However, SNP ascertainment bias may influence inferences from the genotyping results of South African sheep breeds. Therefore, samples from Dorper, Namaqua Afrikaner (NA), South African Merino (SA Merino) and South African Mutton Merino (SAMM) were genotyped to determine the utility of the OvineSNP50 chip for these important South African sheep breeds. After quality control measures had been implemented, 85 SA Merino, 20 Dorper, 20 NA and 19 SAMM samples remained, with an average call rate of 99.72%. A total of 49 517 (91.30%) SNPs on the chip met quality control measures and were included in downstream analyses. The NA had the fewest polymorphic loci, 69.20%, while the SAMM, Dorper and SA Merino had between 81.16% and 86.85% polymorphic loci. Most loci of the SA Merino, Dorper and SAMM had a MAF greater than or equal to 0.3. In contrast, the NA exhibited a large number of rare alleles (MAF < 0.1) and a uniform distribution of other loci across the MAF range (0.1 < MAF < 0.5). The NA exhibited the least genetic diversity and had the greatest inbreeding coefficient among the four breeds. The results of the Dorper, SA Merino, and SAMM compare favourably with those of international breeds and thus demonstrate the utility of the OvineSNP50 chip for these breeds. Effects of SNP ascertainment bias, however, could be seen in the number of non-polymorphic loci and MAF distribution of the three commercial breeds in comparison with those of the NA. The implementation of methods to reduce the effect of SNP ascertainment bias and to ensure unbiased interpretation of genotype results should therefore be considered for future studies using OvineSNP50 chip genotype results. <![CDATA[<b>Spirulina as a functional ingredient in broiler chicken diets</b>]]> In recent years there has been increased interest in the production of novel functional foods by utilizing eco-friendly materials and methods. Therefore, the present study was undertaken to determine the effects of dietary spirulina (Spirulina platensis), a blue-green microalga, on growth performance, meat oxidative stability and fatty acid profile of broiler chickens. One hundred and twenty one-day-old broiler chickens of mixed sex were weighed individually and assigned randomly to three treatment groups with four replications of 10 birds. All birds were housed in floor cages with litter, and conventional breeding and management procedures were applied throughout the 42-day trial period. The treatment groups were as follows: control: 0 g spirulina/kg feed; S05: 5 g spirulina/kg feed; S10: 10 g spirulina/kg feed. The birds were fed with maize and soybean meal-based commercial diets for the starter (1 to 14 days), grower (15 to 28 days) and finisher (29 to 42 days) periods. Feed and drinking water were offered to all birds ad libitum. The results of the experiment showed that bodyweight gain (at 21 d and 42 d), feed conversion ratio and mortality did not differ among the groups, nor did breast and thigh meat lipid oxidation differ among the groups. The fatty acid profile of the thigh meat was enriched in polyunsaturated fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid after spirulina supplementation. Therefore, spirulina could be a promising functional ingredient in broiler chicken nutrition. <![CDATA[<b>Dietary effects of buckwheat <i>(Fagopyrum esculentum) </i>and black cumin <i>(Nigella sativa) </i>seed on growth performance, serum lipid profile and intestinal microflora of broiler chicks</b>]]> The study was conducted to investigate the effects of different levels of buckwheat seed (BWS) with black cumin seed (BCS) supplementation on the performance, serum lipid profile and intestinal bacterial flora in broiler chicks. One hundred and twenty day-old Cobb-500 broiler chicks were randomly allotted equally to four experimental groups, designated T1 (untreated control, no BWS and BCS); T2 (10% BWS + 1.5% BCS); T3 (20% BWS + 2.5% BCS); and T4 (30% BWS + 3.5% BCS), respectively. The study lasted for 30 days. Average bodyweight, weight gain, total feed intake, feed conversion ratio (FCR), and serum lipid profile (serum total cholesterol, HDL-cholesterol, triglycerides) were determined and intestinal bacterial flora (total viable bacteria, Escherichia coli, Salmonella and Lactobacillus sp.) were counted. The results of the study showed that BWS and BCS significantly improved final bodyweight gain of group T2 compared with the control group. Higher levels of buckwheat and black cumin did not improve growth performance of the chicks. Serum cholesterol and triglyceride concentrations significantly decreased with an elevation of HDL-cholesterol concentration as the level of BWS and BCS increased. In BWS diets supplemented with BCS pathogenic bacteria, E. coli and Salmonella spp. were suppressed. These findings suggest that 10% BWS with 1.5% BCS supplementation to broiler ration could be considered an alternative to hazardous synthetic antibiotics for safe poultry production.