Analgesic effects of morphine and butorphanol in broiler chickens

Objective

To evaluate analgesic efficacies of morphine and butorphanol in lame broiler chickens.

Effect of dietary inclusion of spray‐dried porcine plasma on performance,some physiological and immunological response of broiler chickens challenged with Salmonella sofia

This study was conducted to investigate the effect of spray‐dried porcine plasma (SDPP) in broiler chickens under Salmonella sofia disease challenge. The experiment comprised five starter diets: positive control (no supplement), diet supplemented with in‐feed antibiotics (IFA; salinomycin 0.05% + zinc bacitracin 0.033%) and diets supplemented with SDPP at 10 or 20 g/kg diet. All four of these groups were challenged with S. sofia, while a fifth group was unchallenged and used as the negative control. The experimental diets were fed to 14 days; then, the birds were switched to commercial‐type grower and finisher diets. Oral inoculation of the challenged groups with S. sofia occurred on day 8, 10 and 12. Body weight was significantly higher in the birds fed diets containing IFA and SDPP than in the challenged control group, but it was only significant in starter and grower phases. In general, there was an improvement in the weights of the immune‐related organs, but it was only significant for the weight of the bursa of SDPP‐fed birds at 13 days. At day 13, blood potassium content was lower and the concentrations of IgG and IgM tended to be lower in the birds fed on low‐SDPP starter diets than those of the other groups. There were significant differences in the concentration of lactic acid in the ileum and acetic acid, formic acid, butyric acid and propionic acid in the caeca. Inclusion of SDPP to the starter diets of broiler chicks had positive effects on broiler performance, immunity and gut health during exposure to highly pathogenic conditions.     

Effects of dietary fiber and threonine on performance,intestinal morphology and immune responses in broiler chickens

The present experiment was conducted to investigate the effects of fiber and threonine (Thr) on growth performance, intestinal morphology and immune responses of broiler chickens. A total of 420 one-day-old mixed sex broiler chicks (Ross 308) were randomly divided into 6 experimental diets and 5 replicates of 14 chicks based on a factorial arrangement (2 × 3) from 1 to 42 d of age. Experimental factors included dietary supplemental fiber type (no supplemental fiber [NSF], 30 g/kg sugar beet pulp [SBP] or 30 g/kg rice hull [RH]) and Thr inclusion level (100% or 110% of Thr requirement recommended by breeder company [Ross 308]). Growth performance of broilers was assayed at different periods of the experiment. Intestinal morphometric features were measured at 21 d of age. Antibody titer against sheep red blood cells (SRBC), Newcastle and influenza disease viruses were measured on d 30 of trial. Dietary inclusion of SBP and RH significantly decreased feed intake and weight gain during the entire rearing period (P < 0.05). Interaction of fiber and Thr had no beneficial effects on the performance of chickens across the entire rearing phase. Dietary supplementation of 110% Thr required level improved jejunal morphometric features (P < 0.05), whereas its inclusion with fibrous materials failed to show the same effects. Dietary supplemental Thr together with SBP significantly increased antibody production against SRBC (P < 0.05). In conclusion, although supplemental 30 g/kg fibrous materials impaired growth performance, inclusion of SBP along with 110% Thr level improved the humoral immunity in broiler chickens.     

In ovo carbohydrate supplementation modulates growth and immunity‐related genes in broiler chickens

A study was undertaken to investigate the role of in ovo administrated carbohydrates on the expression pattern of growth and immune‐related genes. In ovo injections (n = 400) were carried out on the 14th day of incubation into the yolk sac/amnion of the broiler chicken embryos. Expression of growth‐related genes: chicken growth hormone (cGH), insulin‐like growth factor‐I & II (IGF‐I & II) and mucin were studied in hepatic and jejunum tissues of late‐term embryo and early post‐hatch chicks. Expression of candidate immune genes: Interleukin‐2, 6, 10 and 12 (IL‐2, IL‐6, IL‐10 and IL‐12), Tumour necrosis factor‐alpha (TNF‐α) and Interferon gamma (IFN‐γ) were studied in peripheral blood monocyte cells of in ovo‐injected and control birds following antigenic stimulation with sheep RBC (SRBC) or mitogen concanavalin A (Con‐A). Glucose injection significantly increased the expression of IGF‐II gene during embryonic period and both cGH and IGF‐II in early post‐hatch period, while ribose‐injected chicks had higher expression of IGF‐II gene during embryonic stage. Enhanced mucin gene expression was also observed in fructose‐injected chicks during embryonic age. Glucose‐injected chicks had higher expression of IL‐6 or IL‐10, while those injected with fructose or ribose had higher expression of IL‐2, IL‐12 and IFN gamma. It is concluded that in ovo supplementation of carbohydrates might help in improving the growth of late‐term embryos and chicks. In ovo glucose could modulate humoral‐related immunity, while fructose or ribose might help in improving the cellular immunity in broiler chickens.     

Effect of organic acids or probiotics alone or in combination on growth performance,nutrient digestibility,enzyme activities,intestinal morphology and gut microflora in broiler chickens

A feeding trial was conducted to determine the effect of organic acids or probiotics alone or in combination on growth performance, nutrient digestibility, enzyme activity, intestinal morphology and gut microflora in broiler chickens (Ross308). A completely randomized design was used, with 1,440 broiler chicks across four treatments and five replications of 72 chicks each. The chicks in the control treatment were fed on a control diet (CD), whereas for the other treatment groups, the CD was supplemented with 0.2 g/kg organic acids (CDOA), probiotics (CDP) or a combination of organic acids and probiotics (CDOAP). All the chicks were fed ad libitum during the feeding trial throughout 35 days. A total of 20 chicks were randomly allotted to individual metabolic cages to measure the nutrient digestibility (35–42 days) and the digestive enzyme activities (42 days). The intestinal morphology and gut microflora of 80 chicks were examined at the end of experiment. There were no significant (p > .05) differences in the feed intake, body weight gain or feed conversion ratio of the chicks across the four dietary treatments. The crude fibre digestibility was significantly increased in chicks fed on CDOA or CDOAP relative to CD (p < .05). Nutrient utilization, in terms of digestive enzyme activities and excreta thermal property, was unchanged by any supplementation. The chicks fed on the CDOAP had significantly higher duodenal villi height and crypt depth than the chicks fed on CDOA (p < .05). This dietary treatment dramatically improved gut microflora by decreasing the population of Escherichia coli and increasing the Lactobacillus spp.:E. coli ratio. Based on our investigations, supplementation of organic acids and probiotics in chick diets can increase the ability to digest crude fibre and villus height and decrease intestinal E. coli without impairing growth performance.     

Effects of dietary inclusion of silymarin on performance,intestinal morphology and ileal bacterial count in aflatoxin‐challenged broiler chicks

This study was conducted to investigate the effect of dietary supplementation of silymarin on performance, jejunal morphology and ileal bacterial population in broiler chicks intoxicated with a mix of aflatoxins. A total of three hundred thirty six 7‐day‐old Ross broiler chicks were randomly distributed between seven experimental groups with four replicates of 12 birds each. Experimental treatments consisted of a control group (unchallenged), and a 2 × 3 factorial arrangement, including two aflatoxin levels (0.5 and 2 ppm) and three levels of silymarin (0, 500 and 1000 ppm). Birds were challenged with a mix of aflatoxins from 7 to 28 days of age. Results showed that increasing aflatoxin level resulted in decreased average daily feed intake (ADFI) and weight gain (ADWG), consequently impaired feed conversion ratio (FCR) throughout the trial period. Dietary supplementation of silymarin resulted in the marked increases in ADFI and ADWG, and improved FCR values in aflatoxin‐challenged chicks. Ileal bacterial populations at days 28 and 42 of age were increased by incremental levels of aflatoxins. On the other hand, dietary silymarin supplementation suppressed ileal populations of Escherichia coli, Salmonella, Klebsiella and total negative bacteria in aflatoxicated birds. Increase in dietary aflatoxin level resulted in the decreased villi height, villi height‐to‐crypt depth ratio (VH:CD), villi surface area and apparent villi absorptive area, while it increased crypt depth, goblet cell count and lymphoid follicular diameter. Feeding silymarin at the level of 1000 ppm increased villi height and VH:CD in aflatoxicated birds. Present results indicate that dietary inclusion of silymarin could improve performance by suppressing ileal bacteria and enhancing absorptive surface area in aflatoxin‐challenged broiler chicks.     

The effect of dietary lysozyme with EDTA on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle

Lysozyme is a potential replacement for antibiotics in the poultry industry. Two trials were conducted using new or used litter to determine the effect of 100 ppm lysozyme in feed on growth performance and intestinal microbiota of broiler chickens in each period of the growth cycle. The new litter trial and used litter trial were each analyzed as a one-way analysis of variance with length of time in which 100 ppm lysozyme was fed to the birds as the main factor (no lysozyme d zero to 35; positive lysozyme d zero to 4; positive lysozyme d 5 to 14; positive lysozyme d 15 to 24; positive lysozyme d 25 to 35; positive lysozyme d zero to 35; positive virginiamycin d zero to 35). Effects of lysozyme were not detected under clean conditions (P > 0.05). When used litter was provided, growth performance was not improved by lysozyme (P > 0.05). However, feeding lysozyme to birds from d 5 to 14 and throughout the trial reduced the number of E. coli in the ileum compared with feeding virginiamycin (positive lysozyme d 5 to 14 and zero to 35, and virginiamycin d zero to 35: 1.7 × 10⁴ cfu g⁻¹, 1.9 × 10⁴ cfu g⁻¹ and 9.3 × 10⁴ cfu g⁻¹, respectively) to birds (P < 0.05). Dietary lysozyme at 100 ppm can change intestinal microbiota of broiler chickens.     

Ileal MUC2 gene expression and microbial population,but not growth performance and immune response,are influenced by in ovo injection of probiotics in broiler chickens

1. The objective of present study was to evaluate the effects of intra-amniotic injection of different probiotic strains (Bacillus subtilis, Enterococcus faecium and Pediococcus acidilactici) on the intestinal MUC2 gene expression, microbial population, growth performance and immune response in broiler chicken.

2. In a completely randomised design, different probiotic strains were injected into the amniotic fluid of the 480 live embryos (d 18 of incubation), with 4 treatments and 5 replicates. Ileal MUC2 gene expression, microbial profile, growth performance and immune response were determined.

3. Injection of probiotic strains, especially B. subtilis, had significant effect on expression of the MUC2 on d 21 of incubation and d 3 post-hatch, but not on d 19 of incubation.

4. Injection of the probiotic strains decreased significantly the Escherichia coli population and increased the lactic acid bacteria population during the first week post-hatch.

5. Inoculation of probiotics had no significant effect on antibody titres against Newcastle disease virus, antibody titres against sheep red blood cell and cell-mediated immune response of chickens compared to control.

6. In ovo injection of the probiotic strains had no significant effect on growth performance of broiler chickens.

7. It was concluded that injection of probiotic bacteria especially B. subtilis into the amniotic fluid has a beneficial effect on ileal MUC2 gene expression and bacteria population during the first week post-hatch, but has no effect on growth performance and immune response in broiler chickens.     

Hypophagic and dipsogenic effect of the 5‐HT1A receptor agonist 8‐OH‐DPAT in broiler chickens

The effects of the 5‐HT_1A receptor agonist 8‐OH‐DPAT on food and water intake in male broiler chickens were investigated. The injection of 25 or 50 μg/kg of 8‐OH‐DPAT 15 min before refeeding in fasted animals produced a decrease in food intake. No effect was observed in drinking. The injection of 25 or 50 μg/kg of the 8‐OH‐DPAT 60 min after the start of refeeding did not produce any significant modification in food intake. No effect on drinking was recorded. The agonist 8‐OH‐DPAT injected 15 min before water presentation in water‐deprived chickens, produced an increased drinking 60 min after the presentation of water. No effect on food intake was observed. The results show that the effect on food intake of the agonist 8‐OH‐DPAT in fasted–refed broiler chickens was similar to those observed in mammals and layer‐strain chickens. However, the agonist did not alter significantly the food intake when the broilers were fed 60 min before the injection. These results are contrary to the observed effects in mammals and in layer‐strain chickens. Probably, the selection for rapid growth rate in broilers causes modifications in the feeding control pattern. The comparison between broilers and layers strain may be a useful tool to elucidate the complex mechanisms involved in food and water intake regulation in chickens.     

Effect of an organic acid blend and phytase added to a rapeseed cake‐containing diet on performance,intestinal morphology,caecal microflora activity and thyroid status of broiler chickens

The experiment was carried out on 96 female broilers, allocated to eight groups of 12 birds kept in individual cages. Two basal wheat‐ and soyabean meal‐based diets containing 150 g/kg of rapeseed expeller cake were formulated, differing in the level of P: 7.1 g/kg in diet H or 5.9 g/kg in diet L. Rapeseed cake supplied 3.15 μmol alkenyl glucosinolates per gram of diet. The eight treatments were: basal diets only, basal diets + phytase (1000 U/kg), basal diets + organic acid blend (OA, 6 g/kg), or basal diets + both additives. Diets were fed from day 8 to 28 of life. The results showed that the lower dietary P content and OA supplementation did not significantly affect feed intake or BWG, while both increased (p < 0.001) after phytase supplementation. Tibia ash content as well as tibia ultimate strength were lower (p < 0.001) in birds fed diets L compared with diets H, and increased (p < 0.01) with phytase supplementation of diet L, while OA had no influence on either parameter. Dietary P levels and OA supplementation had no influence on the pH of gut digesta, but the pH of jejunal digesta increased following phytase supplementation (p < 0.01). Morphological measurements of the small intestinal mucosa of chicks indicated that OA added to diet L depressed villi height (p < 0.001) and crypt depth (p < 0.001); both parameters increased after phytase supplementation (p < 0.01). The lower total SCFA as well as acetic, propionic and butyric acid concentrations in caecal digesta indicated lower activity of caecal microflora in birds fed diets L compared with H. OA supplementation had no influence, while phytase supplementation increased the concentration of acetic acid in caecal digesta. Supplementation of diets with either phytase or OA increased thyroid weight by 16% (p < 0.01) and 11% (p < 0.05) respectively. The increase in thyroid weight because of phytase supplementation was greater at the lower dietary P level, and the greatest when both phytase and OA were added to the diet.     

Effect of macronutrient ratio of the pre‐starter diet on broiler performance and intermediary metabolism

The aim of this study was to investigate the influence of isoenergetic substitution between the three energy delivering macronutrients in pre‐starter diets on performance and intermediary nutrient metabolism in broiler chickens. From hatch until 5 days of age, 600 chicks, collected during peak of hatch, were fed one of the three experimental pre‐starter diets with isoenergetic (13 MJ metabolisable energy/kg) substitutions between fat (43 vs. 108 g/kg), protein (126 vs. 240 g/kg) and carbohydrates (391 vs. 510 g/kg). After 5 days, commercial grower and finisher diets were provided. Pre‐starter composition influenced body weight until slaughter age, although not statistically verifiable. Broilers fed the low protein (LP) pre‐starter had the lowest body weight in relation to chickens on the low carbohydrate or low fat pre‐starter diet. After hatch, chicks on the LP pre‐starter diet were able to use the residual yolk sac more rapidly to fulfil their protein requirement, which is reflected in small intestine and liver development. Also, plasma metabolite levels were influenced mostly by the LP pre‐starter, indicating that the main focus for the requirements of newly hatched chicks should be on proteins. Furthermore, optimal nutrition during the first day’s post‐hatch should take into account the contribution of the yolk.     

The effect of dietary supplementation with globin and spray-dried porcine plasma on performance,digestibility and histomorphological traits in broiler chickens

This study evaluated the effects of globin and spray-dried porcine plasma (SDPP) on growth performance, digestibility, nitrogen retention, energy retention efficiency (ERE) and intestinal morphology of broiler chickens. A total of 336-day-old male broiler chickens were reared from 1 to 40 days of age and fed 3 diets (8 replicates/diet, 14 birds/replicate) during 3 feeding phases: starter (1–12 days), grower (12–25 days) and finisher (25–40 days). Isonitrogenous diets were formulated by replacing gluten protein isolate contained in the control diet (C diet) with 2% (starter) or 1% (grower and finisher) spray-dried porcine plasma in the plasma diet (SDPP diet). The globin diet (G diet) was obtained by adding globin on the top of C diet at a dose of 0.08% for the whole rearing period. Total tract apparent digestibility (aD), nitrogen retention and ERE were assessed during the three growing phases. At 12  and 40 days of age, one bird per pen was slaughtered to sample gut, liver, spleen and bursa of Fabricius for histomorphological investigations. The SDPP diet increased body weights of chickens at 12 (+60 g; p < .001), 25 (+101 g; p < .001) and 40 days (+130 g; p = .018) of age compared to C and G diets. Also SDPP improved crude protein aD (+9.7%) and ERE (+12.3%) during the starter phase (p < .001). Dietary globin and SDPP inclusion did not affect either the gut morphology or the histopathological findings in birds at 12 and 40 days of age, despite a numerical (+6.90% and +7.40% respectively) villus height improvement in the SDPP group. Overall, these results confirm that dietary supplementation with SDPP and, to a lesser extent, with globin can improve growth performance and dietary protein and energy utilization in broiler chickens without effect on gut functionality.     

Effects of epigallocatechin gallate on lipid metabolism and its underlying molecular mechanism in broiler chickens

The objective of this study was to investigate the effects of epigallocatechin gallate (EGCG) on fat metabolism and to establish the molecular mechanism of these effects in broilers. Seventy‐two 28‐day‐old male Ross 308 broiler chickens were divided into three groups with different levels of EGCG supplementation for 4 weeks: normal control (NC) group, L‐EGCG (a low‐level supplement of EGCG, 40 mg/kg body weight daily) and H‐EGCG (a high‐level supplement of EGCG, 80 mg/kg body weight daily). After 4 weeks of oral administration, EGCG significantly reduced the level of abdominal fat deposition in broilers. The serum triglycerides and low‐density lipoprotein cholesterol of chickens in H‐EGCG group were also significantly decreased compared with the NC group, and the high‐density lipoprotein cholesterol was notably increased at the same time. Moreover, the vital role of the liver and abdominal adipose tissue in lipid metabolism of poultry animals was examined through gene expression and enzyme activities related to fat anabolism and catabolism in these organs. Our data show that EGCG supplementation for 2 weeks significantly downregulated the expression of fatty acid synthesis and fat deposition‐related genes, and upregulated the expression of genes involved in fatty acid β‐oxidation and lipolysis genes. Simultaneously, the activities of hepatic fatty acid synthesis enzymes (fatty acid synthase and acetyl CoA carboxylase) were significantly decreased, and the activity of carnitine palmitoyl transferase‐1 was notably elevated. The results suggest that EGCG could alleviate fat deposition in broilers through inhibiting fat anabolism and stimulating lipid catabolism in broilers.     

A Saccharomyces cerevisiae RC016-based feed additive reduces liver toxicity,residual aflatoxin B1 levels and positively influences intestinal morphology in broiler chickens fed chronic aflatoxin B1-contaminated diets

The present study was conducted to investigate the ability of Saccharomyces cerevisiae RC016 (Sc)-based feed additive to reduce liver toxicity, residual aflatoxin B₁ (AFB₁) levels and influence intestinal structure in broiler chickens fed chronic aflatoxin B₁-contaminated diets. A total of 100 one-day-old male commercial line (Ross) broiler chickens were divided into 4 treatments, with 5 pens per treatment and 5 broiler chickens per pen. Birds were randomly assigned to 4 treatments, which were namely treatment 1 (T₁), control diet (CD); T₂, CD + Sc at 1 g/kg; T₃, CD + AFB₁ at 100 μg/kg; T₄, CD + Sc at 1 g/kg + AFB₁ at 100 μg/kg. The liver histopathology of broiler chickens fed diets with AFB₁ showed diffused microvacuolar fatty degeneration. The addition of Sc showed normal hepatocytes similar to the control. The small intestine villi from AFB₁ group showed atrophy, hyperplasia of goblet cells, prominent inflammatory infiltrate and oedema. In contrast, the small intestine villi from birds that received the yeast plus AFB₁ showed an absence of inflammatory infiltrate, and atrophy; moreover, a lower number of goblet cells compared to the groups with AFB₁ was observed. The morphometric intestine studies showed that a significant decrease (P < 0.05) in the crypt depth values when Sc was applied to AFB₁-contaminated diets. Although the intestinal villus height and apparent adsorption area did not show significant differences (P > 0.05), there was a tendency to improve these parameters. The residual levels of AFB₁ in livers were significantly reduced (P < 0.05) in the presence of the yeast. The present work demonstrated that the addition of Sc alone or in combination with AFB₁ in the broiler chicken diets had a beneficial effect in counteracting the toxic effects of AFB₁ in livers besides improving the histomorphometric parameters and modulating the toxic effect of AFB₁ in the intestine.     

Effect of herbal feed additives on performance parameters,intestinal microbiota,intestinal morphology and meat lipid oxidation of broiler chickens

ABSTRACT

1. This feeding trial investigated the effects of herbal feed additives on performance of broiler chickens, jejunal and caecal microbiota, jejunal morphology, meat chemical composition and oxidative stability during refrigerated storage.

2. In a 42 days trial, 320 one-day-old broiler chickens were randomly allocated to 4 groups with 4 replicate pens each containing 20 chicks. The control group was fed maize–soybean-based diets. The diets of the other three groups were supplemented with herbal feed additives: HRB1 with Stresomix^TM (0.5 g/kg feed); HRB2 with Ayucee^TM (1.0 g/kg feed); HRB3 with Salcochek Pro^TM (1.0 g/kg feed). The GC/MS analysis of the feed additives showed that the major components of HRB1 were β-caryophyllene (14.4%) and menthol (9.8%); HRB2 were n-hexadecanoic acid (14.22%) and β-caryophyllene (14.4%); and HRB3 were menthol (69.6%) and clavicol methyl ether (13.9%).

3. Intestinal samples were taken at 42 day to determine bacterial populations (total aerobe counts, Lactobacilli, and Escherichia coli) and perform gut morphology analysis. Meat samples were analysed for chemical composition and oxidative stability under storage.

4. The HRB1 group had improved (P < 0.05) body weight gain and tended to have improved (0.05 ≤ P < 0.10) feed conversion ratio, compared to the control group. Jejunum lactic acid bacteria counts were increased (P < 0.001) in groups HRB1 and HRB3, compared to the control group, whereas caecal lactic acid bacteria counts tended to increase (0.05 ≤ P < 0.10) in group HRB1, compared to the control group. Breast meat fat content tended to be lower (0.05 ≤ P < 0.10) in group HRB1. Meat oxidative stability was improved (P < 0.001), and jejunum villus height, crypt depth and goblet cells numbers were increased (P < 0.001) in all three herbal supplemented groups, compared to the control.

5. In conclusion, herbal feed additives may be able to improve both growth performance and antioxidant activity of broiler chickens, based on their phenolic compound content.     

Effects of dietary supplementation with a chlorella by‐product on the growth performance,immune response,intestinal microflora and intestinal mucosal morphology in broiler chickens

This study aimed to determine the effect of different dietary levels of a Chlorella by‐product (CBP) on the growth performance, immune response, intestinal microflora and intestinal mucosal morphology of broilers. In total, 480 one‐day‐old broiler chickens were randomly allotted to four dietary treatments with four replicated pens consisting of 30 chicks. The basal diet was formulated to be adequate in energy and nutrients. Three additional diets were prepared by supplementing 25, 50 or 75 g/kg of CBP to the basal diet. The diets were fed to the broilers ad libitum for 35 days. Result indicated that increasing inclusion level of CBP improved BW gain (linear, p < 0.05). There was no effect of inclusion level of CBP in diets on total cholesterol, triglyceride, aspartate aminotransferase and alanine aminotransferase levels during the 35 days. Plasma IgG, IgM and IgA concentrations increased (linear, p < 0.05) with inclusion level of CBP in diets. Supplementation of CBP in the diets increased (linear, p < 0.05) the concentrations of Lactobacillus in the caecal content and decreased (linear, p < 0.05) the concentrations of Escherichia coli and Salmonella in the caecal content. Villus height increased (linear and quadratic, p < 0.05) with inclusion level of CBP in diets. Crypt depth increased (quadratic, p < 0.05) with inclusion level of CBP, and a decreased villus height: crypt depth ratio (quadratic, p < 0.05) was observed as inclusion level of CBP in diets increased. The results of the current experiment indicate that dietary supplementation of CBP improves growth performance of birds. Dietary CBP has improving Lactobacillus spp. concentrations in the gastrointestinal tract, plasma immunoglobulin concentrations and intestinal mucosal morphology.     

Evaluation of supplementary stevia (Stevia rebaudiana,bertoni) leaves and stevioside in broiler diets: effects on feed intake,nutrient metabolism,blood parameters and growth performance

A perennial schrub, stevia, and its extracts are used as a natural sweetener and have been shown to possess antimicrobial properties. Stevia contains high levels of sweetening glycosides including stevioside which is thought to possess antimicrobial and antifungal properties. Little is known about the nutritional value of the schrub in livestock. This study determined the potential use of the shrub as a prebiotic animal feed supplement in light of the recent ban on the use of antibiotics in animal feed and the role of its constituent stevioside in the effects of the shrub. Male Cobb broiler chicks were fed a basal broiler diet without antibiotic but with performance enhancing enzyme mix (positive control), a basal diet without antibiotic and enzymes (negative control), or diets in which 2% of the negative control diet was replaced with either dried ground stevia leaves or 130 ppm pure stevioside during 2 week starter and 2 week grower periods. Body weight gains, feed conversion, abdominal fat deposition, plasma hormone and metabolites and caecal short chain fatty acids (SCFA) were measured in the broilers at 2 and 4 weeks of age. There was no significant effect of the treatments on feed intake during the starter period but birds fed diet supplemented with stevia leaves and stevioside consumed more feed (p < 0.05) than those fed the positive control diet during the grower period. Weight gain by birds fed the positive control and stevioside diets was higher (p < 0.05) than those fed other diets only during the starter period. Feed/gain ratio of birds fed the positive control and stevioside diets was superior (p < 0.05) to others. There was no effect of the treatments on nutrient retention and water content of the excreta. Dietary stevia leave and stevioside decreased total concentration of SCFA and changed their profile in the ceca. There was no effect of the treatments on pancreas weight. Dietary stevia reduced blood levels of glucose, triglycerides and triiodothyronine (T₃) but had no effect on non-esterified fatty acids. In contrast, stevioside only decreased T₃. Both the stevia leaves and stevioside diets significantly increased abdominal fat content. It is concluded that dietary enzyme growth promoters are beneficial to the broilers only during the starter stage and that inclusion of stevia leaves or stevioside has no beneficial effect on the performance of broilers.     

Effects of thermo‐resistant non‐starch polysaccharide degrading multi‐enzyme on growth performance,meat quality,relative weights of body organs and blood profile in broiler chickens

This research was conducted to study the performance and carcass parameters of broiler chickens fed diets supplemented with heat‐treated non‐starch polysaccharide degrading enzyme. A total of 432 one‐day old Ross 308 broiler chickens were allocated to five treatments: (i) CON (basal diet), (ii) E1: CON + 0.05% multi‐enzyme, (iii) E2: CON + 0.1% multi‐enzyme, (iv) E3: CON + 0.05% thermo‐resistant multi‐enzyme and (v) E4: CON + 0.1% thermo‐resistant multi‐enzyme, each treatment consisted of six replications and 12 chickens in each replication. The chickens were housed in three floor battery cages during 28‐day experimental period. On days 1–7, gain in body weight (BWG) improved by feeding the diets supplemented with thermo‐resistant multi‐enzyme. On days 7–21 and 1–28, chickens fed the diets containing thermo‐resistant multi‐enzyme showed improved (p < 0.05) BWG and feed conversion ratio (FCR) compared to CON group. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme affected the percentage of drip loss on d 1 (p < 0.05). Drip loss percentage on days 3 and 5 and also meat colour were not affected significantly. Supplementing the diets with multi‐enzyme or thermo‐resistant multi‐enzyme did not affect the relative weights of organs but compared to CON group, relative weight of breast muscle increased and abdominal fat decreased (p < 0.05). Among measured blood constituents, chickens fed supplemented diets with thermo‐resistant multi‐enzyme showed higher (p < 0.05) IgG. Counts of red and white blood cells and lymphocyte percentage were not affected. In conclusion, the results demonstrated that supplementing pelleted diets with thermo‐resistant multi‐enzyme improved performance of broiler chickens.