Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 49 num. 2 lang. <![CDATA[SciELO Logo]]> <![CDATA[<b>Co-products in maize-soybean growing-pig diets altered <i>in vitro </i>enzymatic insoluble fibre hydrolysis and fermentation in relation to botanical origin</b>]]> The study examined the effects of botanical factors and fermentation-based, high-level dilution of co-product feeds in maize-soybean growing-pig diets on enzymatic insoluble fibre hydrolysis and fermentation. Feed insoluble fibre residues that were recovered after pepsin-pancreatin digestion were subjected to Roxazyme® G2 (Roxazyme) versus Viscozyme L® V2010 (control) hydrolysis, and to 64-hour fermentation using pig faecal inoculum. The control diet was a 13 MJ metabolizable energy, 141 g total dietary fibre/kg dry matter maize-meal/hominy chop-soybean diet, which was diluted with maize cob, soybean hulls, barley brewer's grains, lucerne hay or wheat bran in 12 MJ metabolizable energy, 246 g total dietary fibre/kg dry matter iso-nutrient, single co-product test diets. Fermentable insoluble fibre was employed in a computerized iterative selection of ingredients in two iso-nutrient 11 MJ metabolizable energy 319 total dietary fibre/kg dry matter mixed fibre test diets for maximal contrast (high (HF) versus low (LF)) in fermentability. Insoluble fibre extractive pepsin-pancreatin digestibility differed between feed ingredients, and the single co-product test diets, and between the HF and LF mixed co-product diets. Fibre digestibility depended on both the origin and enzyme, with interaction, whereby carbohydrases expressed similar low (0.04 - 0.05) insoluble fibre digestibility for maize cob, moderate (0.12) digestibility for wheat bran and brewer's grain, with inferior Roxazyme G2 digestibility for maize hominy chop (0.02 vs 0.10) and meal (0.04 vs 0.16), dehulled soybean meal (0.02 vs 0.17), lucerne hay (0.08 vs 0.18), and soybean hulls (0.05 vs 0.33). Co-product-enzyme affinities were expressed in single fibre diets. Low Roxazyme-basal fibre affinity limited its comparative single co-product (0.03 - 0.07 vs 0.16 - 0.22) HF (0.07 vs 0.17) and LF (0.4 vs 0.20) dietary fibre digestibility. Screening for HF/LF did not affect enzymatic digestion, though enzyme combination increased HF, but not LF digestibility. Gas and short chain fatty acid production predicted fermentability proportionately in the declining order of dehulled soybean > maize > soy hulls > maize hominy chop > wheat bran >lucerne hay > brewer's grain = maize cob. Induced HF and LF contrast was significant. Co-product fibre enrichment decreased fermentability for all except the soy hull and HF diets. Cereal fibre yielded proportionately less acetate, with more propionate and butyrate, and a greater butyrate shift for maize fibre. The HF fibre induced more ACE and less butyrate. Biomarkers of deleterious proteolytic fermentation were high for lucerne (iso-butyrate) and soy hulls (iso-valerate). In conclusion, high-level and fermentation based co-product feed dilution into maize-soybean growing pig diets altered enzymatic insoluble fibre hydrolysis and fermentation in relation to botanical origin. Roxazyme expressed weak hydrolytic potency on maize and soybean insoluble fibre. <![CDATA[<b>Effect of probiotics, <i>Saccharomyces </i>spp.Kb-5 and Kb-8, in diets on growth performance and cholesterol levels in ducks</b>]]> The study was conducted to determine the effect of the probiotics, Saccharomyces spp.Kb-5 and Saccharomyces spp.Kb-8, on growth performance, carcass characteristics, serum and meat cholesterol levels in ducks. Two hundred and forty 1-day-old healthy male ducks were randomly allocated to four treatment groups: A) basal diet (control), B) basal diet + 0.20% Saccharomyces spp.Kb-5, C) basal diet + 0.20% Saccharomyces spp.Kb-8, and D) basal diet + 0.10% Saccharomyces spp.Kb-5 + 0.10% Saccharomyces spp.Kb-8. Growth performance, carcass characteristics, and serum and meat cholesterol levels were determined when the ducks were 56 days old. Saccharomyces spp.Kb-5 and Saccharomyces spp.Kb-8, and the incombination, increased bodyweight gains, feed efficiencies and carcass weight significantly, but not affect the amount of feed consumed. The administration of Saccharomyces spp. results in significant lower serum and meat cholesterol concentrations compared to the control. It was concluded that the addition of Saccharomyces spp.Kb-5 and Saccharomyces spp.Kb-8, and the incombination, in the diet increased growth performances, feed efficiency and carcass weight, and decreased serum and meat cholesterol concentrations in male ducklings. <![CDATA[<b>Hydrogen peroxide concentration and DNA fragmentation of buffalo oocytes matured in sericin-supplemented maturation medium</b>]]> This study was conducted to investigate the effects of sericin on meiotic maturation, hydrogen peroxide (H2O2) concentration and deoxyribonucleic acid (DNA) fragmentation in buffalo oocytes. Oocytes were matured in vitro in tissue culture medium (TCM-199) with in vitro maturation (IVM) groups under several conditions, namely without bovine serum albumin (-BSA), (+BSA), and 0.025%, 0.05%, 0.1% and 0.25% (w/v) sericin. The results showed that supplementation of the maturation medium with 0.05% sericin significantly increased the rate of oocytes that reach metaphase II compared with other groups, except for the 0.025% sericin-treated group. Intracellular H2O2 concentrations in oocytes of all groups were measured using 2',7'-dichlorodihydrofluorescein diacetate (DCHFDA). The concentration of H2O2 in matured oocytes treated with 0.05% sericin was lower than in other groups. DNA fragmentation and the nuclear status of oocytes were examined using the terminal deoxyribonucleotidyl transferase-mediated dUTP digoxigenin nick end-labelling (TUNEL) method. The total proportion of TUNEL-positive oocytes at the MII stage was lower in the 0.05% sericin group. The results indicate that addition of 0.05% sericin to the maturation medium may improve nuclear maturation and may inhibit DNA fragmentation in oocytes by decreasing H2O2 concentrations. <![CDATA[<b>Prebiotic effects of oligosaccharides extracted from palm kernel expeller on different levels of <i>Salmonella typhimurium </i>infection in chicks</b>]]> Prebiotic effects of oligosaccharides extract from palm kernel expeller (OligoPKE) on Salmonella typhimurium were investigated in chicks in two experiments. Results of the first experiment showed that OligoPKE reduced the colonization of Salmonella typhimurium in the cecum and increased the immunoglobulin A (IgA) production in the blood and jejunum. The second experiment further investigated the prebiotic efficacy of dietary supplementation of OligoPKE on three levels of Salmonella typhimurium infection (1.0 x 104 Colony-forming unit (CFU)/mL; 1.0 x 106 CFU/mL and 1.0 x 108 CFU/mL) in chicks. OligoPKE reduced the colonization of Salmonella in the medium and high levels of infection. IgA level in serum and jejunum content increased significantly in all the three levels of infection when chicks received OligoPKE in their diet. Interleukin 8, and 10; interferon-α; and tumour necrosis factor genes were up-regulated in the jejunum of the infected chicks, and OligoPKE down-regulated these gene expressions. Results of the current study indicated that OligoPKE, an oligosaccharides extract from palm kernel expeller, is capable of reducing colonization of Salmonella typhimurium in young chicks, and boosted their immunity. <![CDATA[<b>Effect of feeding regime on the performance and blood parameters of male and female broiler chickens</b>]]> The aim of the present study was to evaluate the effect of feeding regime on changes in growth, mortality, carcass composition, and blood parameters of male and female broiler chickens during feed restriction and the realimentation period. In the experiment, males and females were split into three groups: i) ADL, a group fed ad libitum during the entire experiment; ii) R80, a group that received 80% ad libitum; and iii) R65, a group that received 65% ad libitum. Restriction was applied in both groups from 7 to 14 days old. Daily weight gain (DWG) was reduced significantly in males to 35% in R80 and 39% in R65, and in females to 40% in R80 and 45% in R65. Insignificant compensatory growth occurred in the last week of the growing period. Feed restriction reduced mortality, with a higher mortality reduction in the R65 groups. There was no effect of feed restriction on dressing percentage or thigh yield. However, breast yield was lower and abdominal fat yield was higher in restricted birds. There was a minor effect of feeding regime on blood biochemical and haematological measurements. Males showed significantly higher compensatory growth, feed intake, mortality and thigh yield than females, but dressing percentage and abdominal fat levels were significantly higher in females. Blood total protein and urea concentration were affected by the interaction between sex, group and age. <![CDATA[<b>Effects of transportation and storage duration of Japanese quail eggs on hatchability</b>]]> This study was conducted to investigate the effects of transportation from breeder's farm to hatchery, and of storage duration on the hatchability of quail eggs. Hatching eggs were divided into two groups. The first group was stored for seven days and the second for 14 days. Half of each group was subjected to 200 km transportation before initiation of embryonic development, and the other half was not transported. Relative weight loss ratios varied significantly with storage duration, but did not vary after transportation. Hatchability of fertile eggs varied with storage duration and transportation, but only the effects of storage x transportation were found to be significant. Embryonic mortality for the first period of 14-day storage (22.1%) was significantly higher than those stored for seven days. In the second period (days 10 - 16), embryonic mortality ratios varied significantly with storage and transportation. Transportation after 7-day storage influenced the hatchability of fertile eggs negatively, compared with non-transported eggs stored for seven days. On the other hand, transportation after long-term storage had a higher hatchability of the fertile eggs than the non-transported eggs stored for the long time. These findings suggest that the vibration through transportation over the secondary road after long-term storage influenced the embryonic development of hatching eggs positively. Thus, the discarded chick ratio of the long-term + transport group was lower than short-term + transport group, and improved the hatchability of fertile eggs. <![CDATA[<b>Genotype imputation as a cost-saving genomic strategy for South African Sanga cattle: A review</b>]]> The South African beef cattle population is heterogeneous and consists of a variety of breeds, production systems and breeding goals. Indigenous cattle breeds are uniquely adapted to their native surroundings, necessitating conservation of these breeds as usable genetic resources to sustain efficient production of beef. Current projections indicate positive growth in human population size, with parallel growth in nutritional demand, in the midst of intensifying environmental conditions. Sanga cattle, therefore, are invaluable assets to the South African beef industry. Modern genomic methodologies allow for an extensive insight into the genome architecture of local breeds. The evolution of these methodologies has also provided opportunities to incorporate deoxyribonucleic acid (DNA) information into breed improvement programs in the form of genomic selection (GS). Certain challenges, such as the high cost of generating adequate numbers of dense genotypic profiles and the introduction of ascertainment bias when non-commercial breeds are genotyped with commercial single nucleotide polymorphism (SNP) panels, have caused a lag in progress on the genomics front in South Africa. Genotype imputation is a statistical method that infers unavailable or missing genotypic data based on shared haplotypes within a population using a population or breed representative reference sample. Genotypes are generated in silico, providing an animal with genotypic information for SNP markers that were not genotyped, based on predictive model-based algorithms. The validation of this method for indigenous breeds will enable the development of cost-effective low-density bead chips, allowing more animals to be genotyped, and imputation to high-density information. The improvement in SNP densities, at lower cost, will allow enhanced power in genome-wide association studies (GWAS) and genomic estimated breeding value (GEBV)-based selection for these breeds. To fully reap the benefits of this methodology, however, will require the setting up of accurate and reliable frameworks that are optimized for its application in Sanga breeds. This review paper aims, first, to identify the challenges that have been impeding genomic applications for Sanga cattle and second, to outline the advantages that a method such as genotype imputation might provide. <![CDATA[<b>Genetic variability in a population of Letelle sheep in South Africa</b>]]> The purpose of the study was to gain insight into the genetic variability of the Letelle sheep breed, a breed that has been managed as a closed population for 90 years, with no new genetic material being permitted into the breed. The Letelle is a South African developed dual-purpose sheep breed and is classified as a Merino type with a Spanish Merino origin. The breed exhibits good fine wool characteristics and yields high-quality mutton. Line-breeding, family-breeding, and inbreeding are applied, and multiple sire matings are practised to prevent a sire from having a large influence on the national flock. Ear samples were collected from 10 animals each from 10 commercial and 11 seed-stock flocks and genotyped using 17 microsatellite markers. Unbiased heterozygosity ranged from 0.58 to 0.68 and the observed heterozygosity from 0.52 to 0.65. The estimated effective population size (Ne) was 228.2 - 321.9. Results from analysis of molecular variance (AMOVA), a Bayesian assignment test, and a neighbour-joining (NJ) tree suggested that no genetic sub-structure existed within this population and that the seed-stock and commercial flocks could be regarded as one genetic population. The average within flock (FIS) and within breed (FIT) inbreeding coefficients were 10.1% and 14.5%, respectively. Despite the level of inbreeding, levels of genetic diversity were moderate and potentially provide opportunities for future selection and adaptation. Further testing could identify flocks in which conservation management is required as well as those with high genetic variability, which would provide the best reservoir for selection to adapt to future climatic challenges. <![CDATA[<b>Effects of processed recycled poultry bedding with tannins extracted from pomegranate peel on the nutrient digestibility and growth performance of lambs</b>]]> The aim of this experiment was to decrease the rumen degradability rate of recycled poultry bedding (RPB) protein using pomegranate peel extract (PPE) as the tannin source. Furthermore, to study the effects of this processing method on nutrient digestibility, rumen and blood parameters, nitrogen retention, growth performance, carcass characteristics of male Arabi lambs, and the economic value of diets and production. Thirty-two Arabi lambs (19.7 ± 2.45 kg bodyweight, 90 ± 12 days old) were randomly assigned to one of four dietary treatments including a control and RPB treated with 20%, 25% and 30% PPE on a dry matter basis. Compared with the control, treatment of RPB with PPE did not affect apparent digestibility of dry matter, organic matter, neutral detergent fibre or acid detergent fibre. However, apparent crude protein digestibility decreased significantly. Dietary treatments had no effect on ruminal pH, although ammonia-nitrogen and blood urea nitrogen concentration decreased in diets containing RPB treated with PPE. All lambs were in a positive nitrogen balance and the highest nitrogen retention was observed in the dietary group that was fed RPB treated with 25% PPE. Adding PPE to RPB up to 25% significantly increased final bodyweight, total gain, average daily gain and warm carcass weight, and improved the economic values of production as it decreased the price of each kilogram diet and cost per unit of production (each kilogram bodyweight). The dry matter intake and gain efficiency were unaffected by treatments. Therefore, treatment of RPB with 25% PPE in the finishing diets of Arabi lambs improved growth performance and nitrogen metabolism without affecting feed intake and gain efficiency, and warm carcass weight, and improved the economic values of production. <![CDATA[<b>Effect of <i>Leucaena leucocephala, </i>as a protein source in a total mixed ration, on milk yield and composition of Saanen milk goats</b>]]> This study examined the effects of diets with two protein sources (oilseed cake meal (OSCM) and Leucaena leucocephala hay) on the performance of lactating goats that were fed a total mixed ration (TMR). Thirty Saanen milk goats were divided into two groups, which were fed one of the two TMRS, with or without Leucaena hay at 25% of the DM. The TMRs were formulated to be iso-nitrogenous, iso-energetic and isoneutral detergent fibre, while using two sources of crude protein, namely i) Leucaena hay; and ii) oilseed cake meal OSCM from soybean, sunflower, and cottonseed. No significant differences were revealed in body condition score, bodyweight change, milk yield and milk composition, such as milk fat (%), milk lactose (%), somatic cell count (x 10³ cells/mL) and milk protein (%) during the entire lactation period. In contrast, goats fed the TMR with Leucaena hay had a lower milk urea nitrogen (mg nitrogen/dL) level than those fed the control diet (with OSCM). It was concluded that replacing a proportion of oilseed cake meal with Leucaena in Saanen milk goats fed TMR does not negatively influence milk production and composition. <![CDATA[<b>Fatty acids profile and oxidative stability of eggs from laying hens fed diets containing hemp seed or hempseed cake</b>]]> High levels of polyunsaturated fatty acids (PUFAs) are desirable in eggs for its nutritional quality, but render them vulnerable to oxidation. The aim of this trial was to assess the effects of dietary intake of hemp (seeds or cake) on the fatty acid (FA) profile and oxidative stability of eggs. The control diet (C), which was composed of corn, soybean meal and sunflower oil (2.5%), was compared with two experimental diets that were designed to replace sunflower oil with fat from hemp seed (HS diet) or hempseed cake (HC diet). One hundred and twenty Tetra-SL LL laying hens (24-week old) were used in a 10-week trial. Each treatment was replicated five times with eight birds each. Average hen-day egg production was not affected by feeding either the HS or the HC diet. The α-linolenic acid (ALA) concentration in eggs was increased by substituting the HS- or HC-based diets fed to the hens with dietary ALA. Similar deposition profiles were exhibited by eicosapentaenoic acid (EPA) and docosahexaenoic acids (DHA) in yolks in response to increasing the dietary ALA supply. The HS group showed a greater concentration of egg yolk ALA and EPA than the HC group, which had a higher concentration of linoleic acid (LA). These alterations in yolk composition resulted in n-6 : n-3 FA ratio values as low as 2.98 and 4.15 for HS and HC, respectively, compared to 11.07 for the control diet. The atherogenicity index and cholesterol level were not affected by hemp (seed or cake) inclusion, while the thrombogenicity index decreased when compared to the control diet. On days 0, 15 and 30 of storage (4 °C), two eggs were selected randomly from each replicate (totalling 10 eggs per treatment) and analyzed. The PUFAs were not affected by storage. An exception occurred in the HC group, in which eggs had lower n-6 FA content. Egg storage for 30 d led to a reduction in egg α-tocopherol and an increase of malondialdehyde (MDA) concentration, an indicator of lipid peroxidation. The HS treatment resulted in the lowest MDA (0.22 mg MDA/kg yolk for fresh eggs and 0.35 mg for eggs in 30-day storage). The study demonstrates that the level and type of PUFAs, level of α-tocopherol and duration of egg storage significantly affected the oxidative stability of eggs. The results obtained suggest that the inclusion of hemp seed appears to be more effective in maintaining the oxidative stability of egg lipids than hempseed cake. <![CDATA[<b>Effects of dietary inclusion of commercial toxin binders and prebiotics on performance and immune responses of broiler chicks fed aflatoxin-contaminated diets</b>]]> This study aimed to evaluate the efficiency of the dietary inclusion of commercial toxin binders (CTs) and prebiotics on growth performance, immune responses, intestinal morphology and blood variables of broiler chicks fed with aflatoxin and non-aflatoxin-contaminated diets. Six hundred one-day-old male Ross 308 broiler chicks, initial weight of 42 ± 3 g, were used in 10 treatments with six replications (n = 10 birds). ASRI1 and ASRI2 commercial toxin binders and lactose prebiotic were included in their diets. Experimental diets included: 1) basal diet without aflatoxin and additives (NC); 2) basal diet containing aflatoxin (PC); 3) NC diet containing ARSI1; 4) NC diet containing ARSI2; 5) NC diet containing prebiotics; 6) PC diet containing ARSI1; 7) PC diet containing ARSI2; 8) PC diet containing prebiotics; 9) PC diet containing ARSI1+prebiotics; and 10) PC diet containing ARSI2+prebiotics. Growth performance, humoral and cellular immune responses, jejunal morphology and some blood variables were assessed. Results showed that broiler chicks fed with a PC diet showed a higher feed conversion ratio and lower body weight in the grower and finisher periods. Broiler chicks fed with PC diets showed lower immunoglobulin G and M and also cellular immunities compared to the NC diet. The PC group also showed lower values for villus length, villus width and crypt depth, and higher values for liver enzyme activities compared to the PC diet. However, dietary inclusion of prebiotics and CTs, in single and combined form, improved growth performance in grower and finisher periods, cellular and humoral immunities, intestinal morphology and the serum concentration of triglycerides, cholesterol, glucose and liver enzyme activities of broiler chicks fed with aflatoxin. <![CDATA[<b>Characterization of surface orientation and tenderness of sous vide processed edible offal and psoas muscle from Dohne Merino sheep</b>]]> The microstructural orientation and tenderness of edible offal and the psoas minor muscle from Dohne Merino sheep were compared in this study. Following evisceration and cleaning, fresh meat samples were collected from slaughtered lambs and ewes of different age groups and thermally processed to varying degrees of doneness using sous vide apparatus. A scanning electron microscope (SEM) was used for the characterization of the surface orientation and elemental composition. The results for tenderness showed that edible offal with anisotropic orientation had higher Warner-Bratzler shear force (WBSF) values, but those with some degrees of uniformity (isotropicity) in their surface orientation were comparatively tender. The rumen and trachea from the lambs, six-tooth and eight-tooth sheep at 10 - 12, 23 - 36 and 28 - 48 months old at slaughter had the highest WBSF values among all the meat samples. Our findings showed that edible offal from the lambs with isotropic orientation was more tender and richer in protein than those from ewes. Also, processing the psoas minor muscle and edible offal with sous vide at 100 °C in the shortest cooking time of 30 minutes had the greatest effect on tenderness of the meat samples. In descending order, the psoas minor muscle, liver and tongue from the lambs were found to be inherently more proteinaceous than other meat samples. The differences observed in the tenderness and protein contents of the edible offal and the psoas muscle could be attributed to variations in the microstructural organization of the muscle fibres in Dohne Merino and to their response to thermal processing.