Effects of different yeast cell wall supplements added to maize- or wheat-based diets for broiler chickens

1. Three experiments were carried out to study the effects of two experimental yeast cell wall (YCW) supplements, one from the yeast extract industry and the other from the brewery industry, added to maize or wheat based-diets, on performance and intestinal parameters of broiler chickens (Ross 308).

2. In the first and second experiments, a completely randomised block design with 4 experimental treatments was used: T-1) Negative control, no additives T-2) Positive control, avilamycin group (10 mg/kg feed), T-3) Yeast extract-YCW (500 mg/kg), and T-4) Brewery-YCW (500 mg/kg feed). There were 6 replicates of 20 (experiment 1) and 22 (experiment 2) chicks per treatment.

3. In experiment 1 (wheat based diets), yeast extract-YCW increased BW and daily feed intake (42 d). The effects were comparable to those of avilamycin. In experiment 2 (maize based diet), avilamycin, yeast extract-YCW and brewery-YCW treatments improved the feed conversion ratio with respect to the negative control group (0 to 14 d).

4. At 24 d, in both experiments, the ileal nutrient digestibility and ileal bacterial counts were not affected by any experimental treatment. In maize diets, lower intestinal viscosity was obtained with avilamycin, yeast extract-YCW and brewery-YCW than with the negative control. In wheat diets, yeast extract-YCW and brewery-YCW reduced intestinal viscosity.

5. A third experiment was conducted to study the effect of yeast extract-YCW on animal performance, intestinal mucosa morphology and intestinal viscosity. A 2 × 2 factorial arrangement of treatments was used; one factor was the dietary yeast extract-YCW supplementation (0 or 500 mg/kg feed) and the other the cereal in the diet (maize or wheat).

6. At 43 d, the heaviest BW was in chickens fed on yeast extract-YCW compared to those given the negative control. At 22 d, yeast extract-YCW increased villus height, mucus thickness and number of goblet cells with respect to negative control.

7. Results of these experiments suggest that supplementation of yeast extract-YCW to broiler chicken diets increased animal performance by favouring intestinal mucosal development.     

Comparison of the supplemental effects of Saccharomyces cerevisiae and antibiotics in low-protein and high-fibre diets fed to broiler chickens.

Two experiments were completed to compare the supplemental effects of yeast Saccharomyces cerevisiae and sub-therapeutic antibiotics in high-fibre and low-protein diets for broiler chicks. In experiment 1, yeast was added at 1.5, 3.0 and 6.0 g kg-1 while penicillin, tylosin or neoterramycin were added at 150 mg kg-1 into different batches of a high-fibre diet containing 250 g kg-1 palm kernel meal. Saccharomyces cerevisiae and antibiotics increased BW, BWG, FCR, feed intake, carcass and breast weights above the control. Small intestine weight was reduced by antibiotics, while yeast caused a lower deposition of abdominal fat. Liver weights of different treated broilers were similar. The performance indices were superior on penicillin and 3.0 g kg-1 yeast compared to other supplements evaluated. In the second experiment, 1.5 and 3.0 g kg-1 of yeast, and 0.75 mg kg-1 of procaine penicillin, zinc bacitracin and tylosin were separately added to a 180 g kg-1 crude protein diet. Performance of the chicks with additives was compared with unsupplemented negative and positive controls containing 180 and 210 g kg-1 crude protein respectively. Broilers fed with supplements had superior BW, BWG, FCR and feed intake compared to the negative control, but carcass data were similar. Dietary penicillin increased BW, BWG, feed intake more than other supplements, but yeast stimulated higher FCR. Data from both studies indicated that Saccharomyces cerevisiae comparatively increased growth and carcass weight and reduce abdominal fat, therefore, it can serve as a natural substitute for antibiotics in broiler diet.     

Immune-modulatory effects of dietary Saccharomyces cerevisiae cell wall in broiler chickens inoculated with Escherichia coli lipopolysaccharide

1. An experiment was conducted to study the effect of yeast (Saccharomyces cerevisiae) cell wall (YCW) supplemented in diets of broiler chickens challenged with Escherichia coli lipopolysaccharide (LPS).

2. One-day-old broiler chicks were randomly distributed into 24 cages (6 replicate cages; 8 birds/cage) and were inoculated with 0 or 1 mg/kg body weight E. coli-LPS (d 4 and 9) and 0 or 500 mg YCW/kg feed, resulting in a 2 × 2 factorial arrangement of treatments. Experimental diets did not include coccidiostats, in-feed antibiotics or enzymes.

3. On d 21, the inoculation of E. coli-LPS reduced weight gain and feed intake and increased feed conversion ratio (FCR) of birds, an effect maintained until 28 d. In contrast, chickens given diets with YCW improved the FCR at both 21 and 28 d of age.

4. E. coli-LPS challenge reduced the relative weight of bursa of Fabricius, except when chickens were given YCW, which resulted in an interaction. Supplementation of broiler diets with YCW exacerbated the cellular immune response as measured by the delayed cutaneous hypersensitivity response test.

5. The results of this study suggested a benefit on feed efficiency when YCW was added to diets fed to broiler chickens challenged with E. coli-LPS. Part of the mode of action of YCW might be related to better maintenance of immune status in response to microbial challenge.     

Performance and physiological responses of broiler chickens to supplemental guanidinoacetic acid in arginine-deficient diets

1. The present experiment was designed to examine arginine (Arg)-sparing effects of guanidinoacetic acid (GAA) on production performance, intestinal morphology and certain blood parameters in broiler chickens.

2. A total of 300 male broiler chicks (Ross 308) were randomly allotted to 5 dietary treatments in a completely randomised design during 1–15 and 15–35 d rearing periods. Experimental treatments consisted of a basal diet with a reduction in Arg content (CON?; starter: 12.1 g/kg and grower: 11.3 g/kg Arg), a CON? diet supplemented with synthetic Arg equal to the required Arg level (CON+; starter: 13.80 g/kg; grower: 12.37 g/kg) and CON? diet supplemented with three levels of GAA (GAA0.6; GAA1.2; and GAA1.8; g/kg).

3. Supplemental GAA at 0.6 and 1.2 g/kg reduced the adverse effects of the CON? diet on weight gain and feed conversion ratio in the starter period, equal to the effect of CON+ diet. During the entire rearing period, such an effect was only seen for broilers fed CON? diet supplemented with 1.2 and 1.8 g/kg GAA (P < 0.05). Proportional weights of liver and abdominal fat were decreased in birds fed diets containing supplemental Arg and 1.8 g/kg GAA compared to the CON? broilers (P < 0.05). Jejunal villus height and villus height to crypt depth ratio were increased in broilers receiving the CON? diet (P < 0.05). Serum concentration of nitric oxide increased when the CON? diet was supplemented with either Arg or 1.8 g/kg GAA (P < 0.05).

4. Dietary inclusion of GAA had an Arg-sparing effect, whereby 1.2 and 1.8 g/kg of supplemental GAA resulted in greater growth performance during the starter and entire rearing periods, respectively. Supplementation with 1.8 g/kg GAA had significant effects on some carcass and physiological parameters.     

Progress towards reduced-crude protein diets for broiler chickens and sustainable chicken-meat production

The prime purpose of this review is to explore the pathways whereby progress towards reduced-crude protein(CP)diets and sustainable chicken-meat production may be best achieved. Reduced-CP broiler diets have the potential to attenuate environmental pollution from nitrogen and ammonia emissions; moreover, they have the capacity to diminish the global chicken-meat industry's dependence on soybean meal to tangible extents. The variable impacts of reduced-CP broiler diets on apparent amino acid digestibility coefficients are addressed. The more accurate identification of amino acid requirements for broiler chickens offered reduced-CP diets is essential as this would diminish amino acid imbalances and the deamination of surplus amino acids. Deamination of amino acids increases the synthesis and excretion of uric acid for which there is a requirement for glycine, this emphasises the value of so-called "non-essential" amino acids. Starch digestive dynamics and their possible impact of glucose on pancreatic secretions of insulin are discussed, although the functions of insulin in avian species require clarification. Maize is probably a superior feed grain to wheat as the basis of reduced-CP diets; if so, the identification of the underlying reasons for this difference should be instructive. Moderating increases in starch concentrations and condensing dietary starch:protein ratios in reduced-CP diets may prove to be advantageous as expanding ratios appear to be aligned to inferior broiler performance. Threonine is specifically examined because elevated free threonine plasma concentrations in birds offered reduced-CP diets may be indicative of compromised performance. If progress in these directions can be realised, then the prospects of reduced-CP diets contributing to sustainable chicken-meat production are promising.     

Guanidinoacetic acid supplementation is favourable to broiler diets even containing poultry by-product meal

ABSTRACT

1. Two consecutive trials were conducted to evaluate the effects of guanidinoacetic acid (GAA) supplementation (a creatine precursor) and energy levels in broiler diets based on maize-soybean meal (Trial 1) or that additionally included poultry by-product meal (PBPM; Trial 2) on growth performance, carcass yield and breast meat quality to 41 days of age.

2. A total of 792, one-day-old male Ross 308 broiler chickens were randomly distributed into six treatments – three energy levels (sufficient AME_n or 0.2 and 0.4 MJ/kg reduced AME_n) and two GAA levels (0.00% or 0.06%) with eight replicates for each trial.

3. Reducing dietary energy resulted in poorer body weight gain (BWG) and feed conversion ratios (FCR) for each trial (P < 0.05). However, GAA supplementation improved FCR, BWG and European Production Efficiency Factor (EPEF) (P < 0.05).

4. Dietary energy level and GAA addition had no significant effect on carcass parameters, drip loss, pH and chemical composition of breast meat (P > 0.05), but decreased relative liver weight (P < 0.05).

5. It was concluded that, regardless of dietary energy levels, supplementation of GAA to plant-based diets or those including PBPM has the potential to improve growth performance in broilers.     

Inclusion levels and modes of whole grain incorporation into wheat-based rations differentially influence the performance of broiler chickens

1. The objective was to compare three whole grain (WG) inclusion levels (7.5, 15 and 30%) offered to broiler chickens by three modes of WG incorporation: (i) pre-pellet WG inclusion, (ii) post-pellet WG inclusion as a blend of WG and pelleted concentrate and (iii) post-pellet WG inclusion where WG and pelleted concentrate were provided in separate feed trays against a ground-grain, wheat-based control diet.

2. Ten dietary treatments were offered to 6 replicate cages (6 birds per cage) of male Ross 308 chickens from 7 to 28 d post-hatch. The effects of treatment on relative gizzard weights, gizzard contents, pancreatic weights and pH of gizzard digesta were monitored. Parameters of growth performance, nutrient utilisation (apparent metabolisable energy [AME], metabolisable to gross energy [ME:GE] ratios, nitrogen [N] retention and N-corrected AME [AMEn]), apparent starch and protein (N) digestibility coefficients and disappearance rates in for small intestinal segments and concentrations of free amino acids in plasma taken from the anterior mesenteric vein were determined.

3. Whole grain feeding (WGF) did not influence weight gain, but 30% post-pellet blended and 15 and 30% post-pellet separated treatments significantly depressed (P < 0.05) feed intakes while the 30% post-pellet separated treatment improved (P < 0.01) feed conversion ratios (FCR). WGF regimes significantly increased relative gizzard weights.

4. Overall, WGF generated profound responses in AME, ME:GE ratios, N retention and AMEn that were highly correlated with relative gizzard weights. In general, WGF improved starch and protein (N) digestibilities and again there were some correlations with these outcomes and relative gizzard weights.

5. Post-pellet WG inclusions where WG and pelleted concentrate were offered separately provided chickens with the opportunity to choice feed. Birds showed a preference for the relatively high-protein pelleted concentrate and at 30% WG, this resulted in an improvement in FCR of 7.69% (1.260 versus 1.365; P < 0.001) relative to the ground-grain control diet.     

Evaluation of two mycotoxin binders to reduce toxicity of broiler diets containing ochratoxin A and T-2 toxin contaminated grain

In order to assess ochratoxin A (OA) and T-2 toxin (T-2) binding ability of two commercial sorbents, both in vitro and in vivo trials with broilers were performed. Crude OA and T-2 extracts from contaminated grain were used to assess in vitro binding ability of two sorbents (Zeotek [Zk] and Mycofix [Mx]), by quantifying free mycotoxin through an enzyme-linked immunosorbent assay (ELISA) test. For in vivo trial, a 3 x 2 x 2 factorial arrangement was used for this experiment, being the factors: adsorbents (none, Zk, and Mx), OA (0 and 567 parts per billion [ppb]) and T-2 (0 and 927 ppb). OA and T-2 contaminated wheat and corn, respectively, were added to sorghum-soybean meal diets to meet 567 ppb of OA and 927 ppb of T-2. Mycotoxins were fed alone or combined in treatments. After 21 days, blood chemistry, gross, and histological evaluations were performed. Relative weights of liver, kidney, and bursa of Fabricius were obtained. Zk had the highest OA and T-2 in vitro binding ability (100% and 8.67%, respectively). Chickens fed OA with or without sorbents had a lower body weight and feed intake reduction. However, those birds fed T-2 were partly protected by a sorbent. Birds fed both toxins showed toxic additive effects, and no protection of any adsorbent was observed. A significant reduction in plasma proteins, albumin, and globulins was a characteristic observed in all birds fed diets with OA both with or without adsorbents. Uric acid level in blood was increased in all chickens fed OA-contaminated diets. Histological findings observed in birds fed OA-contaminated diets were necrosis of kidney tubular cells, swollen and necrotic hepatocytes, bile ducts hyperplasia, and increased diameter of proventriculus glands. In birds that received T-2 alone, only the liver, with the same kind of lesions, was affected. According to these results, it can be concluded that there is not a relation between in vitro and in vivo trials. OA toxic effects could not be counteracted by any sorbent. T-2 toxicity could be partially counteracted by an adsorbent used in this research.     

Supplementation of xylanase and phospholipase to wheat-based diets for weaner pigs

The effects of supplementing a wheat-based diet for weaner pigs with exogenous xylanase and phospholipase on ileal and faecal nutrient digestibilities and on the level of microbial metabolites in ileal digesta were examined. Fourteen piglets, weaned at 11 days, were fitted with a simple T-cannula at the distal ileum. The pigs were offered a control diet or diets supplemented with xylanase and phospholipase individually or in combination, in a two period crossover design. The combination of xylanase and phospholipase tended to increase the ileal recovery of the amino sugar galactosamine, whereas the concentration expressed in mg/kg dry matter intake of glucosamine was slightly decreased (p < 0.10). There was neither an effect of enzyme supplementation on ileal and faecal digestibility of the other nutrients and energy, nor was there an effect on pH and on the level of microbial metabolites in ileal digesta. However, an increase in ileal and faecal nutrient and energy digestibility with increasing age was observed. The ileal and faecal digestibility coefficients (except for ether extract) were significantly (p < 0.05) higher in experimental period I than in period II. These higher values may be attributed to a lower feed intake during period I. Since a lower level of feed intake is generally associated with a slower rate of passage and a longer retention time of digesta, a positive impact on digestion and absorption of nutrients can be assumed, which, on the other hand, limits the potential of additional enzyme effects.     

Polysaccharidase preparations added to a wheat-based diet: effects on performance and digestive parameters of broiler chickens held at three different locations

1. Three experiments of 39 d were simultaneously conducted to assess the efficacy of three carbohydrase combinations on performance, apparent nutrient digestibility, intestinal morphology and digestive organ relative weights of chickens fed on a wheat-based diet. 2. Experiment 1 was performed under laboratory conditions, with the birds housed in cages. In experiment 2, the birds were placed in floor pens built in a commercial farm, and raised with their contemporaries at the farm. In experiment 3, broilers were reared under industrial management circumstances in commercial farms. A two-phase feeding programme was used: starter from 1 to 21 d of age and finisher from 22 to 39 d. The basal diet without supplementation (BD) and three enzyme preparations (BDF, BDP and BDR) were evaluated. 3. No differences in growth traits were observed among treatments in experiments 1 and 2. 4. When overall growing period was evaluated, all enzyme combinations improved apparent DM ileal digestibility of feed in the three experiments, but significant differences were only found in experiments 2 and 3. For this same period, an increase in apparent CP ileal digestibility of broiler chickens fed supplemented diets against the control group was found in experiment 3. Moreover, a significant greater apparent ileal fat digestibility in the enzyme treatments compared with the control group was shown when broilers were raised under industrial conditions (experiment 3). 5. Enzyme combinations had no effect on villus heights and crypt depths of broilers in experiment 1, whereas, in experiment 2, a greater villus height was found in BDF and BDP treatments than in control birds. 6. There were no differences in digestive organ relative weights among dietary treatments except for pancreas in experiment 1.     

Ocular responses to ammonia in broiler chickens

In two trials, 60 male commercial broilers were placed in each of eight environmentally controlled chambers receiving 0, 25, 50, or 75 ppm aerial ammonia from 1 to 28 days. Birds exposed to 25 ppm (lower concentration) ammonia gas developed ocular abnormalities but at a slower rate when compared with birds exposed to 50 and 75 ppm (higher concentrations). Birds exposed to higher concentrations also developed more severe lesions. With little atmospheric ammonia present after 28 days of the grow-out stage, the corneas indicated signs of healing. Lymphocytes and heterophils were seen in the iris at 49 days in ammonia-exposed birds even when ammonia exposure was terminated at 28 days. The lower ammonia concentrations resulted in abnormalities that were slight when compared with those seen at the higher ammonia concentrations. As measured by the incidence of inflammatory infiltrates in the trachea, lung, and air sacs, respiratory tract tissues did not appear to be affected by any tested level of aerial ammonia. The findings in this investigation represent the first report indicating that ammonia-induced uveitis in chickens clears rapidly after exposure to ammonia ceases.     

Nutrient digestibility and intestinal viscosities in broiler chickens fed on wheat diets, as compared to maize diets with added guar gum

1. Three maize diets containing 0, 1 or 3 g of guar gum per kg and 2 wheat diets were given to male broiler chickens for measurements of growth performance and nutrient digestibility. 2. The intestinal viscosities found with wheat diets were within the range of those observed with the 3 maize diets. The correlations between in vivo and in vitro viscosities were higher with real than with potential applied viscosity. 3. The gain:food ratio decreased (P < 0.05) with the addition of 3 g guar gum/kg. The mean gain:food ratio observed for wheat diets was lower (P = 0.007) than the mean value found for the 3 maize diets. 4. The negative effects of increased intestinal viscosity due to guar gum addition on nutrient digestibility were highest for lipids and lowest for starch. 5. Wheat diets resulted in much lower (P < 0.001) starch apparent digestibility compared to maize diets with added guar gum despite similar mean intestinal viscosities in the 2 groups of diets. Apparent lipid digestibility with wheat diets was lower (P < 0.01) than the value predicted from intestinal viscosity, the predictive model having been calculated with the guar gum added maize diets. Apparent protein digestibility did not differ between wheat diets and guar gum added maize diets. 6. It was concluded that the low apparent digestibilities of starch and lipid observed with wheats could not be attributed only to intestinal viscosity and that other factors appear to be implicated in the low digestibilities observed with the wheat samples tested in the present experiment.     

Effect of food enzymes on AME and composition of digesta from broiler chickens fed on diets containing non-starch polysaccharides isolated from lupin kernel

1. The effects of lupin non-starch polysaccharides (NSPs) on apparent metabolisable energy (AME) and composition of digesta from broiler chickens were examined in a dose-response experiment in conjunction with a single combination of 2 commercial enzyme products known from previous studies to partially depolymerise NSPs in diets containing sorghum, casein and lupin kernel. The 7-d experiment was conducted on broiler chickens (24 to 31 d of age) in metabolism cages. 2. The basal diet used in this study contained (in g/kg) sorghum (low tannin) 800, casein 134, celite 20 and vitamins and minerals 46. The inclusion rate for each enzyme product was 0.2 g/kg. Lupin kernel isolate (containing 560 g/kg total NSPs) replaced some of the sorghum and casein. The dose rates of lupin kernel isolate (50, 100 and 150 g/kg) were equivalent to dietary inclusion rates of 80, 160 and 240 g/kg, approximately, of untreated lupin kernel from Lupinus angustifolius cultivar Gungurru. 3. Inclusion of lupin kernel isolate in the diet depressed AME and bird performance, and raised ileal viscosity and excreta moisture, in a dose-dependent manner. 4. A combination of 2 proprietary enzyme products improved dietary AME by 0.3 MJ/kg dry matter. Enzymes reduced excreta moisture when inclusion of lupin kernel isolate was 50 g/kg (equivalent to lupin kernel at 80 g/kg, approximately) but not at higher inclusions. 5. Food enzymes partially depolymerised some insoluble NSPs in lupin kernel isolate, which increased ileal viscosity and soluble NSP content of digesta. 6. It was concluded that development of appropriate exogenous enzyme products could lead to lupin NSPs being used as an energy source for poultry.     

Energy metabolism of cocks and broiler chickens fed on diets with different carbohydrate sources.

Energy balances of cocks and chickens were measured using the nitrogen-carbon-balance method. In Experiment 1 twelve adult White Leghorn cocks were fed alternately on a basal ration or on a supplemental ration composed of 75% basal diet and 25% carbohydrate source as a supplement. In Experiment 2 six groups of 12 male broiler chickens were fed successively on two diets each with different carbohydrate sources (40% of DM) and on two energy levels. The investigated carbohydrate sources were glucose, fructose, sucrose, maize starch, raw and steamed potato starch, dried sugar beet pulp, tapioca, wheat, maize, rye and barley. In both experiments the energy digestibility of the diets with raw potato starch, beet pulp and barley was significantly lower compared to the other diets. Digestibility of those ranged from 88 to 81%. By simple linear regression no significant differences in efficiency of utilisation of ME of the diets between the carbohydrate sources sugars, starches and cereal grains could be proved. The corresponding MEm values agreed very close among the diets (411 to 429 kJ.kg BW-0.75.d-1).     

Transfer of nitrofuran residues from parent broiler breeder chickens to broiler progeny

The use of nitrofuran antibiotics in food-producing animals is prohibited within the EU. Countries in the EU, as well those intending to export food to the EU, must ensure that their products are free from nitrofuran residues. As a result of recent global problems where chicken meat from a wide range of countries has been contaminated with nitrofuran metabolites, an investigation was performed to discover whether or not residues of the nitrofurans might be transferred from parent breeder chickens to their offspring broilers. Four groups of broiler breeders were each treated with one of the nitrofurans: furazolidone, nitrofurazone, nitrofurantoin or furaltadone. Residues of their side-chain metabolites, AOZ, SEM, AHD and AMOZ, were detected in the fertilised eggs at concentrations up to 1567 microg/kg. However, in the chicks that subsequently hatched from these eggs, residue concentrations of SEM, for example, were only found up to 26.6 and 32.5 microg/kg in liver and muscle, respectively, for 1-d-old chicks. Residue concentrations in tissues had fallen below the detection limit of the analytical method for 40-d-old broiler chicks, for all compounds except for semicarbazide (SEM, the nitrofurazone metabolite). Relatively high concentrations of nitrofurans are available to the newly hatched chick through the egg yolk. However, most of these residues are neither utilised nor deposited in the liver or muscle.     

Effect of inclusion level of linseed on the nutrient utilisation of diets for growing broiler chickens

1. Diets containing linseed at inclusions of 0, 80, 120 and 160 g/kg were evaluated for digestibility of nutrients and AMEn content with male broiler chickens. 2. Increasing the concentration of linseed decreased the retention of nitrogen and the digestibility of amino acids, crude fat and fatty acids of diets. 3. Dietary AMEn (MJ/kg) was also affected by the rate of inclusion of linseed, values decreasing from 14.39 to 12.49. 4. In general, a linear regression model explained the relationship between dietary linseed content and nutritive parameters. However, the quadratic response found for the digestibility of several amino acids and fatty acids indicated a non-additive change in their digestibility. 5. Viscosity ofjejunal digesta was markedly increased by each increment of linseed in the diets. This is attributable to the presence of mucilage in linseed and it might explain many of the results obtained in this study.     

Skeletal changes in broiler chicks and turkey poults fed diets containing ochratoxin A

Broiler chicks and turkey poults were divided at hatching into experimental and control groups. Experimental birds were fed a diet contaminated with 4 ppm ochratoxin A, whereas the ration of control birds was confirmed to be mycotoxin free. Birds were killed at fortnightly intervals up to 10 weeks old and skeletal changes were investigated. Almost all experimental birds developed generalised skeletal osteopenia with disturbed endochondral and intramembranous bone formation. Histological changes in diaphyseal cortices could account for the reduced breaking strength of bones from birds fed mycotoxin, which have been reported by others. One bird showed changes consistent with a diagnosis of hypophosphataemic rickets. In others, however, osteoid formation was defective and changes were interpreted as osteoporosis. Although it might be tempting to suggest that osteoporosis is a result of a direct toxic effect of ochratoxin on osteoblasts, the effect of inanition, inactivity and general debility may be equally important.     

L-arginine supplementation of reduced-protein diets improves pulmonary hypertensive response in broiler chickens reared at high altitude

1. This study was conducted at high altitude (2100 m above sea level). A total of 208 d-old male broilers (Ross 308) were randomised across 16 floor pens and reared up to 42 d. A normal-protein diet (NPD) was formulated according to the National Research Council. A reduced-protein diet (RPD) was prepared with dietary protein reduced by 30 g/kg relative to that of the NPD. Two additional diets were prepared by adding 2 and 4 g L-arginine (ARG)/kg to the RPD. At the end of trial (42 d), blood sampling was done and carcass characteristics were recorded.

2. ARG supplementation of the RPD at 4 g improved feed:gain in the growing stage and throughout the trial compared with the RPD.

3. The right-to-total ventricular weight ratio was significantly increased in birds fed on RPD compared with those fed on NPD or ARG-supplemented RPD.

4. Feeding RPD caused a significant decrease in plasma concentrations of nitric oxide (NO) and uric acid. Plasma NO level, however, was restored by ARG supplementation of RPD. ARG supplementation of RPD, however, significantly reduced the rate of pulmonary hypertension syndrome mortality compared to the negative control fed on RPD.

     

Performance and meat quality of broiler chickens that are fed diets supplemented with Agaricus brasiliensis mushrooms

This trial was performed to study the use of the mushroom Agaricus brasiliensis as an alternative additive to antimicrobial growth promoters in broiler chicken diets and to assess the quality of the broiler chicken breast meat of birds that are fed diets containing this fungus. Thus, 595 1-day-old chicks were reared in reused poultry litter without anticoccidial and antimicrobial additives. The results showed that a concentration of 1.6 g mushrooms/kg diet was ideal for these birds because it provided better bird performance. When the birds’ immune system organs were analyzed, it was found that the addition of both mushrooms influenced the immune system organs of these broiler chickens. Adding A. brasiliensis to broiler chicken diets did not compromise breast meat quality.