Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 47 num. 6 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Castration of male livestock and the potential of immunocastration to improve animal welfare and production traits: Invited Review</b>]]> Growing consumer awareness about animal welfare has led to the assessment of the impact of common farming practices, such as physical castration, on animal well-being under production conditions. Physical castration is used in livestock industries to prevent indiscriminate breeding, control aggression, and improve meat and carcass quality. In terms of animal welfare, physical castration causes pain, decreased growth performance, infection, and mortality. An alternative approach to castration is thus warranted that will ensure optimal growth without compromising the castrated animal's wellbeing. Immunocastration has proved to be an effective method of suppressing the development and functioning of the reproductive system in various domesticated and wildlife species. The effect of immunocastration on production performance is well-documented for both swine and cattle. Although ram lambs used for meat production are often physically castrated, information regarding the potential application of immunocastration in sheep is limited. However, immunocastration may potentially improve the welfare, performance, and meat quality of ram lambs used in commercial meat production systems. The purpose of this review is to compare the application and the effects of immunocastration on male livestock to highlight and motivate the need for further research into its use on ram lambs. <![CDATA[<b>Processing of South African biltong - A review</b>]]> South Africa has been producing biltong for many years and its popularity is increasing locally and internationally. Biltong is commonly grouped with other dried meat products from around the world, but with its unique production method and expanding economic value, an increase in knowledge on the subject is in high demand. In this paper, biltong processing and quality are reviewed to highlight areas in which knowledge is still lacking. It shows that biltong processing varies resulting in the wide physico-chemical characteristics reported in the literature. However, consumer preference is still an area that lacks scientific data/evidence. Previous research on biltong has focused on the pathogenic microorganisms and not on its spoilage and shelf-life. Moreover, the effects of the various processing methods on the physico-chemical characteristics and resulting microbial stability has not been investigated. Knowledge of these could enable an increase in the quality of biltong. <![CDATA[<b>Effects of Silymarin <i>(Silybum marianum) </i>supplementation on milk and blood parameters of dairy cattle</b>]]> The present study was conducted to investigate the effect of dietary silymarin on milk yield, milk fat, and certain blood parameters of dairy cattle. Silymarin is a naturally accepted hepatoprotectant that is used in the treatment of liver diseases in human beings, and has been tested in dairy cows during peripartum. Animals are subject to subclinical fatty liver. In the first part of the study, the silymarin (20 g/head/day) was supplemented to dairy cattle rations in the last 21 days (peripartum) of pregnancy. In the second part of study, silymarin was added to the rations of Holstein dairy cows for three weeks postpartum. A total of 40 Holstein dairy cows at 2nd lactation with 550-600 kg live weight and average body condition score of 3.5 were used. Dairy cows were randomly separated into two treatment groups (20 cows in each). The first group was control (no addition) and the second group was treatment (silymarin supplemented) group. Treatments significantly increased milk yield, but decreased milk protein. Postpartum bodyweight loss was significantly less in the silymarin group than in the control group. Differences in postprandial plasma triglyceride (TRG) and total cholesterol (TC) levels were found to be significant. Plasma alanine aminotransferase (ALT) and total protein (TP) values of the groups were also significantly different. As a result, it was observed that silymarin supplementation of the ration did not have side effects, and peak milk yields could be achieved earlier with silymarin treatment. Application of silymarin is believed to be useful. It was also observed that silymarin treatments speeded up the metabolic adaptation process of the dairy cows at the beginning of lactation. It was suggested that silymarin should be used in transition periods of dairy cattle. <![CDATA[<b>Effects of probiotics on growth performance, blood parameters, and antibody stimulation in piglets</b>]]> The study investigated the effects of probiotic bacteria (Lactobacillus reuteri ZJ625, Lactobacillus reuteri VB4, Lactobacillus salivarius ZJ614, and Streptococcus salivarius NBRC13956) administered as direct-fed microorganisms on growth performance and blood parameters of weaned piglets. Forty-five weaned piglets were divided into five treatments: antibiotic (PC), no antibiotic and no probiotic (NC), probiotic (P1), probiotic (P2), and combination of probiotics (P3). Fecal and ileum samples were collected for microbial count analysis. Blood samples were also collected from the animals at the end of the trial for the hematological and biochemical analysis and the ability of the probiotics to stimulate immunoglobulin G (IgG). Supplementation of probiotics had no effect on feed intake (FI). However, average daily weight gained (ADG) in the P3 treatment was higher than in other treatments and lowered the value of feed conversion ratio (FCR) of weaned piglets. Microbial count of fecal samples did not differ in all the treatments while ileum samples had lower enteric bacteria in P3 treatment when compared to other treatments. Concentration of albumin, globulin, neutrophils and basophils were higher in the NC treatment when compared to other treatment groups. The IgG concentration was highest in P3 compared to other treatments. Results suggested that probiotics have beneficial effects on growth performances, blood parameters, and IgG stimulation of weaned piglets. This advocates that probiotics will offer a significant benefit in pig farming by reducing the risk of post weaning diarrheal syndromes, and therefore enhance pig industry's economy. <![CDATA[<b>Effects of dietary physical form and dietary inclusion of probiotic and enzyme on growth performance, cellular and humoral immunity, and relative weights of lymphoid organs at early period of broiler chickens fed triticale-based diets</b>]]> The aim of the present study was to investigate interactions between feed form and dietary inclusion of probiotics (live organisms) and enzymes on growth performance, cellular and humoral immunity, and relative weights of lymphoid organs of broiler chicks fed a triticale-based diet. A total of 640 broiler chicks were allocated to eight treatments when they were one day old, with four replicates (n = 20 chicks in each). The dietary treatments consisted of feed form (pellets or mash) and dietary supplementation with or without a Bacillus-based probiotic (0.03% diet) and enzyme (carbohydrase, 0.05% diet) in a 2 × 2 × 2 factorial arrangement. Feed conversion ratio (FCR) was calculated based on feed intake (FI) and weight gain (WG). The WG of the broiler chicks fed the pelleted diets containing the enzyme and probiotic (alone or in combination) was greater than that of the birds fed the mash diets without these additives. Significant interaction effects of the enzyme and probiotic on FCR and FI were observed in the starter period. The heterophil : lymphocyte (H : L) ratio of the chicks fed the pelleted diet containing the enzyme and probiotic was lower than that of the birds fed the other diets. The cellular immunity of the birds fed this diet increased after 24 hours, as shown by the results of a challenge experiment with dinitrochlorobenzene (DNCB) or an injection of phytohemagglutinin (PHA). In conclusion, feed form and supplementation of a triticale-based diet with feed enzymes and probiotics can greatly improve the growth performance and immunity of broiler chicks. <![CDATA[<b>Effects of <i>Prosopis laevigata </i>pods on carcass characteristics, non-carcass components, meat quality, fatty acid profile and sensory attributes</b>]]> It was hypothesized that feeding mesquite pods to male Rambouillet lambs would have no negative effects on carcass characteristics, meat chemical composition and fatty acid composition of Longissimus thoracis et lumborum (LTL). Twenty-one male lambs (2.5 months old and 21 ± 1.44 kg bodyweight) were randomly assigned to one of three experimental diets, two of which replaced maize grain and stover with mesquite pods (Prosopis laevigata) (PL): 0 g PL/kg feed (PL0), 250 g PL/kg feed (PL250) and 500 g PL/kg feed (dry matter basis). The feeding trial lasted 72 days. Carcass traits, chemical composition, fatty acid profile, and sensory characteristics of meat were measured. Carcass linear dimensions, non-carcass components, digestive tract and offal, compression value, and chemical composition of meat were similar in all treatments. Dietary inclusion of PL decreased carcass shrinkage loss. Lambs fed PL500 had better muscle conformation and degree of fat. Meat produced by PL-fed lambs was well accepted by panellists who judged meat appearance, colour, flavour, juiciness, toughness, and stringiness. In lambs fed PL0, the LTL muscle was lighter and yellower than that of animals fed PL250 and PL500 diets. Fatty acid composition was altered. The PL0 diet resulted in lower percentages of total trans fatty acids (TFA) and saturated fatty acids (SFA) and higher percentages of most unsaturated fatty acids (UFA) and polyunsaturated fatty acids (PUFA) n-6 compared with PL250 and PL500 diets. Mesquite diets of up to 500 g/kg dry matter (DM) for growing lambs improved carcass quality and nutritional parameters of the meat. <![CDATA[<b>Carcass and meat quality of Boer and indigenous goats of South Africa under delayed chilling conditions</b>]]> This study was conducted to evaluate the carcass and meat quality of Boer goats and unimproved indigenous goats of South Africa, under delayed chilling conditions. Ten goats per breed were used for the study. The goats were slaughtered according to standard abattoir procedures. The dressed carcasses were held at 10-15 °C for 6 hours before chilling at 4 °C until 24 hours (delayed chilling). The pH/temperature values, instrumental colour (CIE L*, a*, b*, chroma and hue angle), surface myoglobin pigments (deoxyglobin, oxyglobin and metmyoglobin), water-holding capacity (WHC), thawing loss, cooking loss, sarcomere length, and Warner Bratzler shear force (WBSF) values were evaluated on samples of the m. longissimus dorsi (LD) and the m. semimembranosus (SM). Carcasses of Boer goats were heavier and had higher chilling loss than those of indigenous goats. There were no breed differences in dressing percentages, pH/temperature values or meat quality characteristics. Overall, the mean ultimate pH values (5.75-5.80), were marginally higher than the recommended pH for desirable eating quality. However, the mean L* (36.3-40.2), a* (18.0-18.8), WHC (0.35-0.39) and metmyoglobin (16.3-18.8%) values were within the range that is acceptable for normal meat. On average, LD samples were tender (WBSF values of 4.43 ± 0.40 kg), but SM samples were marginally tough (WBSF values of 8.45 ± 0.54 kg). This study shows that delayed chilling could be a useful strategy in improving the colour and tenderness of goat meat. <![CDATA[<b>Effect of olive meal and supplemental enzymes on performance traits, blood biochemistry, humoral immunity response and caecal microbiota of broilers</b>]]> This study investigated the growth performance, carcass characteristics, blood biochemistry, humoral immunity and caecal microbiota of broiler chicks fed 0, 2, 4, 6, and 8% olive meal (OM) in diet. In addition, this study investigated the use of enzymatic feed supplements (β-glucanase, phytase and hemicellulase) to enhance digestibility of high fibre diets. At the end of the feeding period (42 days), there were no significant differences among dietary groups on broiler growth performance, including bodyweight (BW) and bodyweight gain (BWG), feed intake (FI), and feed conversion efficiency (FCE). The evaluated carcass traits and meat cuts (breast, drumsticks and wings) did not vary among dietary treatments. Although some minor differences were observed in blood albumin and cholesterol concentrations among groups, the cecum microbiota did not differ in broilers. Antibody titers following vaccinations against infectious bronchitis virus (IBV) and Gumboro disease were higher in birds fed 4% OM. Adding supplemental enzymes to diet had minimal effect on the parameters. Findings from this study support the literature, which suggests that OM is a suitable feed by-product in broiler diets. Moreover, including OM in poultry rations has the potential to provide an economic and environmentally friendly alternative to traditional diets. Finally, the current trial identified that the addition of enzymes was not necessary to achieve optimal productive performance in broiler fed diet containing OM. <![CDATA[<b>Molecular cloning, sequence analysis and tissue expression of bovine imprinted <i>ASCL2</i> gene</b>]]> Achaete-scute like-2 (ASCL2) gene is a maternally expressed gene that encodes a lineage-specific transcription factor that is essential for neurectoderm and trophectoderm development and is implicated in pre-natal and post-natal development in mammals. Using comparative genomics, various in silico sequence analyses were performed to characterize the putative imprinted ASCL2 gene. Additionally, tissue expression analysis between Angus, White Fulani, and N'Dama cattle breeds was conducted, as well as a molecular cloning of the gene transcript from bovine placenta. Four site-specific motifs were identified in the basic helix-loop-helix (bHLH) domain that are highly conserved in cattle, humans and mice. Pairwise comparisons of the coding sequence of cattle, human and mice revealed a dN/dS rate ratio that was significantly less than 1 (Z test). Two synonymous single nucleotide polymorphisms (SNPs) were found within 1 kb of the cloned complementary DNA (cDNA) in cattle. Bovine ASCL2 messenger RNA (mRNA) was relatively expressed in eight adult tissues with the ASCL2 gene differentially expressed in the muscle and skin tissues of the three cattle breeds. The conservation of these site-specific motifs for phosphorylation across the three species suggests a post-translational modification of the gene function and activity of the mammalian ASCL2 gene. <![CDATA[<b>Development and preliminary validation of an automatic digital analysis system for animal fibre analysis</b>]]> New equipment was designed and developed to evaluate the physical characteristics of animal fibres, based on an automatic digital analysis system (ADAS) that allows the capture of a series of real-time images. In the development of the mechanical component, a design tool was used that allows visualization, simulation, and documentation of the product. At the same time, an Atmel (ATmega328) microcontroller was programmed to enable displacement of table coordinates, focus of images, and reading of the temperature and humidity of fibre samples and the environment. The fibre images were processed using artificial vision technology. Algorithms were also developed for edge detection to define the diameter of the fibre in pixels. Finally, calibration was carried out using a regression and standardized samples of wool tops. The authors then weighted the pixels to µm with a standard sample. A friendly graphical interface was developed for management of the built equipment, visualization of results, calibration, data and graphic export, configuration, among others. For validation, average fibre diameter (AFD), standard deviation (SD), coefficient of variation and comfort factor (CF) were compared with values of top wool patterns. Finally, the measurements of OFDA 2000 and FIBER-EC were compared using student t-test and Pearson correlation. The results of the validation showed that the confidence limit of FIBER-EC, which varied between 0.075 and 3.47 µm, is similar to that of the confidence limit of Sirolan Laserscan and OFDA 2000. Accuracy is better than the OFDA 2000 for fibre assessments less than 25 µm, which vary between 0.034 and 0.250 µm. <![CDATA[<b>Effect of freezer storage on quality of <i>M. longissimus lumborum </i>from fallow deer (<i>Dama dama </i>L.)</b>]]> The aim of this study was to analyse changes in the quality of meat (M. longissimus lumborum) from 11 fallow deer (Dama dama L.) bucks, which had been deep-frozen (-26 °C) for 10 months. The proximate chemical composition, physico-chemical properties and sensory properties of the meat were analysed. Fallow deer aged 17-18 months were hunter-harvested in north-eastern Poland in November and December of the same hunting season. The results revealed that freezer storage did not influence the proximate chemical composition of meat (protein, fat, ash) or the content of water-soluble nitrogen compounds. An analysis of the physico-chemical properties of meat revealed that long-term freezer-stored meat was characterized by higher pH, lower contribution of redness (a*) and yellowness (b*), lower chroma (C*), greater natural drip loss, lower ability to bind added water, and greater cooking loss. Freezer storage improved meat tenderness but reduced meat juiciness. The results of the study also indicated that long-term freezer storage (-26°C) of vacuum-packaged meat allowed it to maintain its good quality, which indicates that this storage method could help meet consumer demand for fallow deer meat between hunting seasons. <![CDATA[<b>Effects of false yam tuber meals and charcoal on broiler chicken production and blood parameters</b>]]> The authors investigated the effects of replacing a portion of a commercial broiler feed with false yam tuber meals on broiler growth performance, feed conversion rate (FCR) and blood parameters. Furthermore, wood charcoal was added at various levels to the meals to explore their potential to attenuate toxic effects. One hundred and sixty-eight 28-day-old healthy female broiler chickens (average initial bodyweight 1081.1 ± 66.20 g) were randomly assigned to 28 experimental groups (7 dietary treatments, 4 replicates) of six birds each, using a randomized complete block design. Dietary treatments included the control diet (commercial broiler feed) (C), raw false yam tuber meal (RFY) replacing 50 g/kg of the commercial broiler feed, false yam tuber meal soaked in water (SFY) replacing 150 g/kg of the commercial broiler feed, RFY with 30 g/kg and 60 g/kg wood charcoal, and SFY with 30 g/kg and 60 g/kg wood charcoal. Growth performance, feed intake and FCR were assessed over four weeks. At the end of the experiment, blood samples were collected from 21 birds (three from each dietary treatment) to analyse haematological and serum biochemical parameters. Analysis of variance, Kruskal-Wallis tests, and simple regressions were used to evaluate the effects of the meals and charcoal. The results indicated that broilers fed 150 g/kg SFY had a significantly lower growth rate and poorest FCR. Consequently, highest bodyweights were observed for C and RFY diets. Additionally, blood serum proteins were below the references ranges for birds fed SFY, particularly with additional charcoal. In contrast, RFY could be included at 50 g/kg in broiler chicken diets without any adverse effects on their performance and blood (serum) parameters. Anti-nutritional substances contained in SFY at this substitution level are harmful to the birds, irrespective of whether charcoal is added or not. In contrast, RFY could replace commercial feed at the studied level (50 g/kg). <![CDATA[<b>Using path analysis to predict bodyweight from body measurements of goats and sheep of communal rangelands in Botswana</b>]]> The objective of this study was to determine the practicality of using linear body measurement traits to predict live weight of goats and sheep under communal grazing in three districts of Botswana, namely Central, Kweneng, and Kgalagadi. Pairwise (Pearson) correlations were estimated using bodyweight (BW) and morphological trait measurements, namely heart girth (HG), shoulder height (SH), and body condition score (BCS) for a sample of 1447 goats and 588 sheep. These ranged from 0.19 to 0.94 for goats and 0.44 to 0.94 for sheep, and were statistically significant. In both animals, regardless of sex, the highest positive correlations were found between BW and HG, followed by BW and SH, then BW and BCS. The direct and indirect relationship between BW and morphological traits using a path analysis approach were also estimated. This analysis suggested that the direct effect of HG on BW was higher at 0.761 for male and 0.662 for female goats, respectively. Similarly, the direct effect of HG on BW was higher among sheep at 0.764 for males and 0.882 for females. The direct effects of SH in all the animals were also positively influenced by BW. It was concluded that among these three morphological traits, the most valuable for estimating the BW for goats and sheep in Botswana is HG, followed by SH. BCS was found non-significant. Path analysis therefore has an advantage over previous empirical studies by providing more detailed information on the relationships (direct and indirect) between these variables. A further implication of this study is that a conversion table could be constructed to help smallholder farmers to estimate the live weight of their sheep and goats from linear measurements. This would aid in the management and marketing of their livestock. <![CDATA[<b>Effect of <i>Moringa oleifera</i> (Lam.) pods as feed additive on egg antioxidants, chemical composition and performance of commercial layers</b>]]> The present study was designed to investigate the influence of Moringa oleifera (Lam.) pod meal (MPM) on production, immunity, and functional food index of chicken eggs. Two hundred HyLine W36 layer birds aged 50 weeks, 1469 ± 46.63 g, were assigned to four treatments in a completely randomized design, with five replicates and ten birds each. Diets A, B, C, and D were formulated with the same caloric and protein levels, but with differing MPM dose levels of 0, 5, 10, and 15g MPM/kg finisher diet, respectively. Data for production performance, quality, and chemical composition of eggs were analysed by one-way ANOVA, and means were compared with Duncan's multiple range test. As a result of this study, feed conversion ratio (FCR) and egg mass (EM) were significantly decreased and recorded lowest in Group B, which was offered 5 g/kg above the basal diet. Bioactives such as β-carotene, quercetin, and selenium levels were increased (540, 121, & 72.21µg/100g of yolk, respectively), whereas cholesterol levels in egg yolk and serum were decreased significantly, that is, 201.87 mg/100g and 8.47 mg/dl, respectively. Serum biochemical indicators, including serum glutamic-pyruvic transaminase (SGPT), glucose, creatinine and cholesterol levels, were lowered significantly. Proximate analysis of egg yolk showed that moisture and ether extract were decreased, whereas crude protein (CP), ash and minerals, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and phosphorus (P) contents were increased. The outcomes of this study showed that MPM supplementation affects EM, serum biochemistry and bioactive compounds of the egg yolk positively. <![CDATA[<b>Effect of a dietary probiotic blend on performance, blood characteristics, meat quality and faecal microbial shedding in growing-finishing pigs</b>]]> The current study aimed to evaluate the effect of a dietary probiotic blend on growth performance, blood characteristics, meat quality, and faecal microbial population in growing-finishing pigs in a 12-week experiment. Pigs were assigned to two dietary treatments: a control basal-diet without probiotic blend (No-Pro) and a test-diet including the probiotic blend (Pro) according to pig bodyweight (BW) at the dose of 100 mg/kg of BW. Pigs fed the probiotics had higher final BW and increased average daily gain (ADG), as well as improved feed conversion ratio (FCR). Blood parameters of pigs were not affected by dietary probiotic complex. Meat crude protein and polyunsaturated fatty acids (PUFA) contents were increased in the group fed probiotics, whereas there were no significant differences in the other meat traits. Feeding of probiotics determined a decrease in faecal NH3-N (+15.5%) and butyric acid concentrations, whereas no effects were observed on faecal acetic acid and propionic acid. An increased faecal Lactobacillus concentration was found when pigs fed probiotic blend. Based on our findings, feeding probiotic blend enhanced growth performance and meat quality in growing-finishing pigs, and also decreased faecal NH3-N and butyric acid levels resulting in a viable approach to reduce animal excreta pollution. <![CDATA[<b>A whole farm model for quantifying total greenhouse gas emissions on South African dairy farms</b>]]> This paper presents a model to quantify total greenhouse gas (GHG) emissions from dairy farms. The model, which is based on a whole farm management approach, accounts for the variability that occurs in GHG emissions among farm production and management practices. The variation is accommodated in six dairy farm management systems (FMS), which broadly include typical dairy production systems in South Africa. These are pasture-based with high or low stocking rates, total mixed ration with high or low stocking rates, and partial mixed ration with high or low stocking rates. Three variations of functional units that were used to evaluate the environmental impacts of various FMS are defined as per animal unit = kg CO2-eq head-1 yr-1; per unit of farm area = kg CO2-eq ha-1 yr-1, and per unit of product = kg CO2-eq kg FPCM-1, where FPCM is fat and protein corrected milk. The results show a range of GHG emissions in CO2-eq among theFMS with various methodological approaches because of the large impact from different emission factors, which vary between accounting methods. The more detailed equations were recommended to effectively improve environmental impacts. These more detailed non-linear equations tended to predict more biologically realistic emissions when compared with the linear equations in which over or under-predictions of GHG were observed. The most prominent drivers for GHG emissions across all FMS were from enteric methane (CH4) and nitrous oxide (N2O) from soil management. Rankings among FMS varied according to output methodology and functional units. GHG emissions expressed per animal or per unit area differ greatly from those expressed from a given level of product. In conclusion, the accounting methodologies that are described in this paper to predict GHG emissions of animal-related origin performed sufficiently across all FMS, and could be applied to quantify the carbon footprint of dairy production systems in South Africa. <![CDATA[<b>Potential of oak acorn with and without polyethylene glycol as an alternative to corn in broiler diets</b>]]> This study was conducted to investigate the potential for replacing corn with oak acorn (OA), a tannin-rich feedstuff, and the possible role of polyethylene glycol (PEG) in reducing detrimental effects of OA on broilers. A 3 × 2 factorial arrangement of treatments was used with three levels of OA (0, 150, and 200 g/kg diet), with and without 10 g/kg PEG. A total of 528 one-day-old male and female Cobb 500 broiler chicks were randomly assigned to one of six experimental treatments, with four replicates of 22 birds each. OA was included in the starter (days 1-21) and finisher (days 22-42) diets as a replacement for corn, without changing the dietary levels of other ingredients. The results indicated that dietary inclusion of OA, without PEG, significantly reduced bodyweight gain (BWG) overall (days 1-42) and resulted in worse finisher and overall feed conversion ratios (FCR). PEG had no significant effect on the performance of birds fed diets without OA, but improved overall the BWG of birds receiving 150 and 200 g/kg OA as well as finisher and overall the FCR of birds given 150 g/kg OA. Liver and pancreas weights were not significantly influenced by OA level, PEG or their interaction. Feeding with 200 g/kg OA had deleterious effects on some tibia traits. In conclusion, a significant interaction between OA level and PEG indicates that PEG has the potential to reduce the adverse effects of OA, leading to improved performance. Thus, up to 150 g/kg OA could be included in PEG-supplemented diets, without adverse effects on performance or the tibia traits of broilers. <![CDATA[<b>Effects of dietary <i>Aloe vera</i> crude extracts on digestive enzyme activities and muscle proximate composition of GIFT tilapia juveniles</b>]]> This study investigated the effects of dietary Aloe vera powder extract on the activities of digestive enzymes and muscle composition of Oreochromis niloticus (GIFT strain) juveniles. Five dietary groups were formulated in which A. vera powder was added into a tilapia feed at 0.5%, 1.0%, 2.0%, and 4%/kg feed, and fed for eight weeks. Amylase, trypsin, and lipase activities in the liver and along the alimentary canal (stomach, midgut, and hindgut) varied significantly between dietary groups. Amylase activity was significantly enhanced in the liver of fish fed 0.5, 1, and 2% dietary A. vera, and in the stomach of those fed 1%. Total amylase activity in the gastrointestinal tract (total gut) was significantly enhanced in fish fed 0.5% and 1% compared with control and those fed 4% dietary A. vera. Trypsin activity was significantly enhanced in the stomach of fish supplemented with 0.5% dietary A. vera and in the duodenum of those supplemented with 1%, 2%, and 4% dietary A. vera when compared with the control. Lipase activity was increased in the duodenum of fish fed 1.0% dietary A. vera when compared with the control. Muscle moisture content was significantly lower in all A. vera-supplemented fish, whereas protein was lower in those fed 2% and 4% A. vera diet when compared with the control. Based on second-order polynomial regression analysis, dietary A. vera inclusion level less than or equal to 1.76%, 1.82%, 2.10%/kg feed was determined to be suitable in enhancing carbohydrate, protein and lipid digestion, respectively, in GIFT tilapia in this study. <![CDATA[<b>Humic acid and enzymes in canola-based broiler diets: Effects on bone development, intestinal histomorphology and immune development</b>]]> The objective of the study was to investigate the effects of dietary inclusion of humic acid and enzymes on bone development, histomorphology of internal organs and the incidence of rickets in broiler chickens fed canola-based diets. In the study, Cobb 500 broiler chicks were used and the following five dietary treatments were administered: control (commercial diet); CM (17.5% canola meal inclusion); CMEnz (17.5% CM inclusion + 0.3g/kg Axtra XAP); CMPh (17.5% CM inclusion + 1.5% potassium humate (PH)); and CMEnzPh (17.5% CM inclusion + 1.5% PH + 0.3g/kg Axtra XAP). These diets were formulated and randomly allocated to 20 pens (experimental units), each housing 11 birds. The birds were phase fed, with the starter diet being given to all birds from day 1 to day 14. During the grower (days 15-28) and finisher phases (days 29-42) birds were fed the experimental diets. Diet differed significantly across all treatments on latency-to-lie (LTL) test. Broilers fed CMEnz had the lowest standing persistence (2.88 ± 2.69 min) and those on CMEnzPh had the highest (11.19 ± 2.69 min), followed by those offered the control diet (9.05 ± 2.69 min). Gross lesion analysis displayed high prevalence of rickets in boilers fed CMEnz diet compared with all other dietary treatments. Intestinal morphometric parameters demonstrated some dietary differences in the height and width of the intestinal villi and intestinal crypts. In conclusion, inclusion of humic acid in canola-based diets appeared to positively influence digestion and assimilation dynamics that were consequential to the improvement in bone and immune development in broilers. <![CDATA[<b>Exogenous carbohydrases do not improve the physiological and meat quality parameters of female Japanese quail fed canola-based diets</b>]]> In an internally controlled environment, a feeding trial using 210 six-week-old female Japanese quail (189.63 ± 11.891 g liveweight) was conducted to evaluate the effect of carbohydrase-treated (endo-1.4-beta-xylanase 5600 TXU/g and endo-1.4-beta-glucanase 2500 TGU/g) canola-based diets on growth performance, haemo-biochemical parameters, carcass characteristics, and meat quality traits. Five isocaloric and isonitrogenous experimental diets were formulated: the control diet (CON) (commercial growers diet with no canola meal (CM) included); the control diet in which 17.5% of soybean meal was replaced with CM (CM0); and the CM0 diet in which a carbohydrase multi-enzyme was added at a rate of 5%, 10% and 15% (CM50, CM100 and CM150, respectively). Diets and clean water were offered ad libitum during the four-week experimental period. Average weekly feed intake (AWFI) and average weekly weight gain (AWG) were used to calculate feed conversion efficiency (FCE). In week 7, no dietary influence was observed on AWFI. In week 8 and week 9, CON stimulated lower AWFI compared with diet CM100. Diets had no significant influence on AWG, FCE, and haemo-biochemical parameters of Japanese quail. Adding carbohydrases had no significant effect on internal organs, carcass and meat quality traits of quail. It was therefore concluded that inclusion of exogenous carbohydrases alone did not improve the utilization of a canola meal-based quail diet. However, there is a possibility that utilization of higher canola levels would be enhanced through multi-enzyme combinations.