Scielo RSS <![CDATA[South African Journal of Animal Science]]> vol. 51 num. 1 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Effect of chitosan oligosaccharide and valine on growth, serum hormone levels and meat quality of broilers</b>]]> Chitosan oligosaccharide (COS) and valine (Val) supplementation will improve growth performance, carcass traits, hormonal profile and meat quality in broilers. To evaluate this hypothesis, based on a 2x4 factorial arrangement, 480 male broilers (Ross 708) were randomly placed in eight treatment groups for two levels of COS (C1: 100 mg/kg, and C2: 150 mg/kg) and four levels of valine (V1: 0.57%, V2: 0.72%, V3: 0.87% and V4: 1.02%) with three replicates (n=24) with 20 birds in each (n i=60; i=1, 2, 3,..., 8.). The results showed that live bodyweight (BW), weight gain (WG), and carcass weight increased, and feed conversion ratio (FCR) decreased with increased supplemental levels of dietary Val at C1 and C2. Abdominal fat reduced linearly for both COS and Val, with a higher reduction response value at C2 and V4. The serum levels of triiodothyronine (T3), thyroxine (T4), testosterone and insulin-like growth factor 1 (IGF-1) presented a linear effect for COS and Val. The proximate composition of breast and leg meat showed that crude fat content decreased linearly for COS and Val with higher reduction response values at V3 for both levels of COS. The ash content rose linearly with increasing concentration of Val at C1, but showed the highest value at V2 when birds were offered C2. There was an interaction between COS and Val for T3, T4, IGF-1, ash content and crude fat. In conclusion, supplementation exerted a significant influence on the growth performance, hormonal profile and meat composition of broilers. <![CDATA[<b>Effects of guavira fruit <i>(Campomanesia adamantium) </i>peel extract on performance and meat quality of broilers</b>]]> This article assessed the performance, carcass yield, and meat quality of finishing broilers fed increasing levels of hydroethanolic extract of guavira fruit peel (HEGP) were assessed. A total of 480, three-weeks-old male broilers were randomly allocated to dietary levels of HEGP (0, 100, 200, 300, 400, and 500 mg/kg), with five replicates and 16 birds each. There was a quadratic effect of HEGP inclusion on weight gain (Wg) and feed conversion ratio (FCR), with the greatest WG and FCR being calculated at levels of 314 and 219 mg/kg HEGP, respectively. Broilers fed diets containing the extract had better performance than those fed an extract-free diet. There was no effect of extract inclusion on carcass yield and cuts. There was a quadratic effect of HEGP inclusion on a* (redness) of thigh meat at 15 min post-mortem, and on waterholding capacity (WHC), with the lowest and highest values being calculated at 270 mg/kg and 263 mg/kg HEGP, respectively. There was a quadratic influence of HEGP inclusion on the malonaldehyde content at 30-day storage, with highest value being calculated at 218 mg/kg HEGP. Dietary inclusion of 219 mg/kg of HEGP resulted in better FCR for broilers in the finishing phase but without improvement in meat quality. <![CDATA[<b>Behaviour, welfare, and tibia traits of fast- and slow-growing chickens reared in intensive and free range systems</b>]]> The behaviour, welfare, and tibia characteristics of fast- and slow-growing chickens were evaluated in free-range and intensive production systems. A total of 720 birds of three strains were subjected to these systems after 21 days of rearing under the same intensive environment. Each treatment was replicated six times with 20 birds in each replicate. Data were collected for welfare aspects, including feather condition, footpad, hock joint and tonic immobility, behavioural features, especially feeding or foraging, sitting, walking, scratching, pecking and dust-bathing, and tibia characteristics, including weight, length, width, medullary canal diameter and robusticity index (4 - 8 weeks). Production system had significant effects on all welfare and behaviour aspects of the birds. However, tibia characteristics were not influenced by production system, except for medullary canal diameter. The strains differed significantly in welfare, tibia characteristics and behaviour. For example, the slow-growing strains had better feather condition, footpad d hock joint scores. Significant interactions of strain and production system were noted for all characteristics. It was recommended that Rhode Island Red chickens could be raised under either production system without compromising their welfare or causing adverse effects on leg health. <![CDATA[<b>Energy manipulation of isonitrogenous diets for broiler chickens</b>]]> A total of 378 unsexed Anak broiler chicks were used to assess the effects of varying energy levels and manipulation on growth, haematology, and carcass traits. The experiment was conducted in two phases. First, one-day-old chicks were randomly assigned to one of three starter diets, which differed in their energy density (LSE: 2786.80 Kcal/kg; OSE: 3015.40 Kcal/kg; and HSE: 3252.20 Kcal/kg). The chicks were assigned to seven replicates per treatment with 18 chicks per replicate. When the chicks were 27 days old, they were randomly re-allocated to three finisher diets (LFE: 2770.66 Kcal/kg, OFE: 2961.74 Kcal/kg, and HFE: 3150.43 Kcal/kg). Thus, there were seven replicates of nine treatments with six chicks per replicate in the finishing phase. The starter and finisher diets were isonitrogenous. Birds fed the OSE and HSE starter diets gained more weight and were heavier at 27 days than birds fed LSE. Energy intake by birds fed HSE was greater than by birds fed OSE, and birds fed OSE had greater energy intake than birds fed LSE. Feed conversion ratio was improved for birds fed OSE and HSE. Birds fed LSE and then HFE consumed the least feed and gained as much or more weight during the finisher phase as any other group. Overall, FCR between days 27 and 50 tended to differ among the treatments (P =0.06). Total protein intake increased with decreasing dietary energy in both phases. Varying dietary energy levels did not affect the haematological parameters, carcass traits and internal organ weights. <![CDATA[<b>Internal quality of commercial eggs stored under conditions that simulate storage from laying to consumption</b>]]> This study evaluated the effects on the internal quality of eggs of various storage environments through which eggs may pass between being laid and being consumed. Commercial eggs (N = 648) from Dekalb White hens were used. Treatments consisted of T1: 28 days at 4 °C; T2: 28 days at 20 °C; T3: 7 days at room temperature (27 °C ± 2 °C) (humidity 55%) and 21 days at 4 °C; T4: 7 days at room temperature and 21 days at 20 °C; T5: 14 days at room temperature and 14 days at 4 °C; T6: 14 days at room temperature and 14 days at 20 °C; T7: 21 days at room temperature and 7 days at 4 °C; T8: 21 days at room temperature and 7 days at 20 °C; and T9: 28 days at room temperature. The characteristics that were evaluated consisted of Haugh unit (HU), yolk index (YI), colour (L*, a* and b*), albumen pH, yolk pH and lipid oxidation. Eggs stored 28 days were darker (L*), and had greater yolk pH and lipid oxidation than fresh eggs. Eggs stored under T1 and T3 conditions had greater HU and YI than eggs stored in the other environments. The albumin pH of eggs stored at room temperature (T9) was highest of the treatments. Yellowness was increased in eggs stored under T4, T6, T8, and T9 conditions. Eggs should be stored under refrigeration as this promotes maintenance of internal quality and mitigates negative effects of previous storage conditions. <![CDATA[<b>Effects of replacing soybean meal with slow-release urea on milk production of Holstein dairy cows</b>]]> The study investigated the effects of replacing soybean meal (SBM) with slow-release urea (SRU) on milk production, milk composition, and rumen fermentation of Holstein dairy cows. Sixteen Holstein cows weighing between 550 and 680 kg in mid lactation were randomly assigned to four dietary treatments in a 12-week study. The treatments consisted of T1: a diet containing 16.7% crude protein (CP), T2: T1 with 0.5% SRU replacing plant protein, T3: T1 with 0.75% SRU replacing plant protein, and T4: T1 with 1.00% SRU replacing plant protein. Animals were fed three times a day with feed being offered ad libitum. Dry matter intake (DMI) and average daily gain (ADG) were not affected by the level of SRU. Feeding SRU did not affect milk production and milk composition significantly, but milk fat and milk urea nitrogen (MUN) levels were increased. Significant differences were observed in ruminal volatile fatty acid (VFA) concentration. Feeding SRU increased butyrate concentration with no significant effects on concentrations of acetate or propionate. Significant differences were observed in cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and nonesterified fatty acid (NEFA) concentrations, but glucose, very-low-density lipoprotein (VLDL) and ß-hydroxybutyrate (BHB) levels were not affected significantly by the treatments. Thus, feeding SRU altered the release rate of ammonia and provided more ammonia nitrogen (NH3-N) for microbial protein synthesis in the rumen. <![CDATA[<b>Beta alanine effects immediately pre- and post hatch on chick quality, carcass yield and meat quality in broilers</b>]]> First, this study aimed to evaluate the effects on hatchability of in ovo supplementation of beta alanine (ßA). Second, it assessed the effects on performance, meat quality and serum constituents of broiler chickens of ßA injection in ovo and of supplementation with βA in feed for the first seven days after hatching. For this purpose, 960 fertilized broiler chicken eggs were distributed to hatchery trays in four treatment groups with six replicates on day 17 of incubation. The treatment groups consisted of eggs that were not injected (T1; negative control), injected with sterile solution with 0.9% salt (T2; positive control), injected with in ovo 1% ßA solution (T3), and not injected, but with chicks were fed 1% βA for the first seven days after hatching (T4). Upon hatching, chicks from T1, T2, and T3 were fed commercial starter feed. All treatments were assessed with six replicates of 28 birds (14 females and 14 males) throughout the grow-out period. As a result of this study, T3 increased hatchability, yolk-free hatching weight and chick quality, and decreased yolk weight and feed access time at hatch. Both T3 and T4 improved carcass yield and meat quality, and T3 increased serum total antioxidant status at 42 days afer hatching. The results demonstrated that in ovo ßA feeding improved hatching characteristics, and ßA administration in ovo or in feed improved carcass yield and meat quality without affecting growth performance. <![CDATA[<b>Effects of dietary fibre level on rumen pH, total microbial count and methanogenic <i>archaea </i>in Bonsmara and Nguni steers</b>]]> A study was conducted to evaluate the effect of the level of dietary fibre on rumen pH, total microbial count and methanogenic archaeacount of Bonsmara (225 ± 10.0 kg live weight) and Nguni (215 ± 10.0 kg live weight) steers. Nine steers per breed were used, aged 8 to 9 months. A 3 x 2 factorial experiment was executed with treatments allocated in a completely randomized design. The treatments were diets which included 64.3% neutral detergent fibre (NDF) for diet 1, 40.4% NDF for diet 2, and 29.9% NDF for diet 3. Steers were fed for 90 days and housed in individual pens. Rumen fluid was collected from steers using a stomach tube. Rumen fluid samples were taken immediately to the laboratory for microbial assay. Data were subjected to analysis of variance (ANOVA). The various levels of dietary fibre did not affect rumen pH and methanogenic archaea count. However, a low-fibre diet yielded high rumen total microbial count for Bonsmara steers and low rumen total microbial count for Nguni steers. Therefore, a low-fibre diet can be applied as a viable strategy to enhance rumen total microbial count in exotic beef breeds and crossbred cattle such as Bonsmara. Nguni steers fed a high NDF diet had higher rumen total microbial count than Nguni steers fed a low-fibre diet. Therefore, a high NDF diet can be used efficiently by feeding it to indigenous breeds and purebred cattle such as Nguni. <![CDATA[<b>Effect of microbial inoculants on the chemical composition and aerobic stability of Tanzania guinea grass silages</b>]]> The present study evaluated the effects of microbial inoculants on chemical changes and aerobic stability efficiency in Tanzania guinea grass silage. The treatments consisted of C: silage without inoculant; I: silage inoculated with Lactobacillus plantarum (CCT 0580) 8.0 x 10(9) CFU g-1, Bacillus subtilis (CCT 0089) 2.0 x 10(9) CFU g-1, and Pediococcus acidilactici (CCT 2553) 1.0 x 10(10) CFU g-1, and L: silage inoculated with Lactobacillus plantarum (CCT 0580) 2.6 x 10(10) CFU g-1 and Pediococcus pentosaceus (CCT 7659) 2.6 x 10(10) CFU g-1. The experimental design was completely randomized, with five replications. There were no treatment effects on the nutritional composition of the silages, but both inoculants were effective in reducing the pH of the silage to 4.80 and 4.83 for I and L, respectively, compared with 5.04 for C. Silage with L had a lower ammonia nitrogen (N-NH3) content than the other silages (9.83%). Despite the lower pH values, the use of inoculants did not reduce fungal and yeast counts or improve the aerobic stability of Tanzania guinea grass silages. <![CDATA[<b>Feather growth, bodyweight and body temperature in broiler lines with different feathering rates</b>]]> Two early feathering sire lines (B1 and B2), two late feathering dam lines (A1 and A3), and an early feathering dam line were evaluated to determine differences in growth, in lengths of primary feathers, in under-wing and rectal temperatures, and in feed intake until the birds were 20 weeks old. The chicks were hatched from eggs collected from 35-week-old hens of pure line broiler flocks. Data were collected at hatch, and at 1, 2, 4, 6, 8, 12, and 20 weeks old Thirty males and 30 females were evaluated for each line. The early feathering genotypes (A2, B1 and B2) had longer primary feathers until they were six weeks old. They also had higher under-wing and rectal temperatures and higher live weight compared with the late-feathering lines (A1 and A3) at one and two weeks old. The males were heavier than females at all ages. However, under-wing and rectal temperatures were similar in males and females at all ages. A positive correlation was observed between the length of primary feathers and live weight in A2, B1, and B2 at six weeks, whereas a negative correlation was observed between the rectal temperature and the length of primary feathers in A1 and A3 at 4 and 20 weeks old. <![CDATA[<b>Effects of fibre source on nutrient digestibility of diets for finishing lambs</b>]]> Inexpensive fibre sources might be used as an alternative to lucerne hay in diets for finishing lambs. Thus, effects of providing fibre from lucerne hay (LH), soyhulls (SH), maize stover (MS) and Eragrostis teff hay (ET) on the nutrient digestibility of diets of finishing lambs with comparable NDF and nutrient concentration were evaluated. Thirty-six individually housed Merino ram lambs (x = 43.03, SD = 3.72 kg) were randomly allocated to four diets (n = 9 lambs/treatment). A digestibility study was conducted to determine the nutrient availability of these diets. Dry matter (DM) intake of SH (1436 g) was lower than ET (1716 g). No differences were recorded between treatments for digestibility of NDF (0.32 - 0.34), acid detergent fibre (ADF) (0.41 - 0.44), and ether extract (EE) (0.67 - 0.75), except that MS (0.23) had lower NDF digestibility. Digestibility of DM, organic matter (OM) and non-structural carbohydrates (NSC) were similar for the LH (0.72; 0.75; 0.96) and SH (0.70; 0.74; 0.95) diets, whereas digestibility of crude protein (CP) (0.71 vs. 0.68), metabolizable energy (ME) (9.49 vs. 8.90 MJ/kg DM), and the available ash fraction (0.39 vs. 0.28) were altered. The SH and ET (8.70 MJ/kg DM) treatments had similar ME concentrations, but ET had lower DM digestibility (0.68). The MS treatment had the lowest ME concentration (8.25 MJ/kg DM). The LH treatment resulted in overall better nutrient availability compared with SH, MS, and ET. <![CDATA[<b>True phosphorus digestibility of cottonseed meal and rice husk supplemented with microbial phytase in broiler chickens</b>]]> This research aimed to determine effects of phytase in cottonseed meal (CM) and rice husk (RH) based diets on true phosphorus digestibility (TPD) by broiler chickens. Two studies were conducted with 576 one-day-old broiler chickens using regression analysis to determine the TPD in these diets and the response to phytase supplementation. Six semi-purified diets were formulated to contain 150 g, 300 g, and 450 g each of CM/kg (experiment 1) and RH/kg (experiment 2) with phytase supplied at 0 and 1000 units/kg. Titanium dioxide was added to the diets at the rate of 5 g/kg as an indigestible maker. A total of 288 broiler chickens in each study were weighed and allotted to the six diets with six replicates of eight birds in a randomized complete block design. The birds were fed the experimental diets until day 26 post hatch. The coefficients of true phosphorus retention (TPR) were 0.8 for CM and 0.78 for RH without phytase; 0.93 for CM and 0.92 for RH with phytase. True phosphorus digestibility was 0.82 for CM and 0.75 for RH without phytase; and 0.95 for CM and 0.92 for RH with phytase. Phytase supplementation resulted in 13.27 and 17.94 % increases in TPD; and 12.29 and 13.61 % increases in TPR by birds fed the CM and RH diets, respectively. Phytase supplementation of CM and RH based diets increased TPD and improved total TPR and true ileal phosphorus digestibility in broiler chickens. <![CDATA[<b>Carcass characteristics of immunocastrated steers finished on diets with different energy patterns</b>]]> The aim of this study was to evaluate the effects of various dietary energy levels on the carcass and meat characteristics of feedlot-finished steers. A total of 27 purebred and crossbred Charolais and Nellore steers were used, with a mean initial age of 22 months and weight of 253 kg. The animals were allotted to a completely randomized design with three treatments and nine replicates each. Dietary treatments were arranged so that the average forage to concentrate ratio (FCR) was equivalent to that of a constant FCR treatment. The treatments consisted of CT (constant FCR at 60 to 40), CT5 (starting with 70: 30 FCR and finishing with 50: 50 FCR, that is, a mean overall FCR of 60: 40), and CT10 (starting with 80: 20 FCR and finishing with 40: 60, that is, a mean overall FCR of 60: 40). The dietary treatments did not affect slaughter weight, carcass weight, carcass conformation, physiological maturity, subcutaneous fat thickness, ribeye area, marbling score, and carcass measurements or the yield of commercial cuts. Chilling loss was higher in CT10 steers (2.41%) than in CT (2.26%) and CT5 (2.15%). <![CDATA[<b>Effect of age of Japanese quail on physical and biochemical characteristics of eggs</b>]]> The aim of the study was to investigate the effects of age of birds on egg quality in Japanese quail. The eggs were randomly selected from among all eggs laid on the same day when the birds were 15, 23 and 31 weeks old. At each time point, 90 fresh eggs were evaluated for their physical and biochemical characteristics. Egg weights were similar over time. At 23 and 31 weeks, the eggs had less shell than at 15 weeks. Crude fat and ash contents of the eggs increased with the age of the birds. Crude protein was also highest in eggs of the oldest quail. At 31 weeks old, the eggs were lowest in pH of yolk and white. Quail that were23 and 31 weeks old laid eggs with significantly higher polyunsaturated fatty acid (PUFA) and lower saturated fatty acid (SFA) contents. The lowest cholesterol content was in egg yolks from 23-week-old quail. The oldest birds had the highest contents of sodium, potassium, zinc, selenium, copper, and manganese. The content and activity of lysozyme decreased with ageing of the birds. From the consumers' point of view, eggs from older birds appeared to be the most valuable. At the same time, as the quail ages, the antibacterial properties of eggs deteriorate, which may indicate a shorter shelf life.