Performance,litter quality and gaseous odour emissions of broilers fed phytase supplemented diets

The effect of graded levels of phytase on performance, bone characteristics, excreta/litter quality and odorant emissions was examined using 720 Ross 308 male d-old broilers. A 2 x 4 factorial arrangement of treatments was employed with 6 replicates of 15 birds per pen. Factors were: diets-positive and negative control(PC, NC); phytase-0, 500,1,000.1,500 FTU/kg. The PC was formulated to meet the 2014 Ross 308 nutrient specifications, whereas the NC was formulated with lower Ca(-1.4 g/kg), available P(-1.5 g/kg), Na(-0.3 g/kg), dLys(-0.2 g/kg) and MEn(-0.28 MJ/kg) equivalent to nutrient matrix values for 500 FTU/kg phytase in the starter,grower and finisher periods(i.e.,downspec diet). On d 24, phytase decreased FCR by 1.6, 4.3 and 4.6 points at inclusion levels of 500.1,000 and 1,500 FTU/kg, respectively(P < 0.01) across all diets. Phytase by diet interactions on BW gain were observed on d 24 and 35(P < 0.01). The effect of phytase was much more pronounced in the NC diet as compared with the PC diet.On d 24, phytase increased BW gain by 37, 55 and 68 g in the PC and 127.233 and 173 g in the NC at 500,1,000 and 1,500 FTU/kg, respectively. Diet by phytase interactions were also observed for tibia ash, litter quality and water to feed intake ratio(P < 0.01) with higher phytase effect in NC as compared with PC.Neither diet nor phytase impacted excreta moisture content on d 18 or 21(P> 0.05). Solid phase microextraction gas chromatography-mass spectrometry(SPME-GC-MS) analysis of gaseous emissions on d 39 indicated no difference in the emission of alcohols, aldehydes, ketones, volatile fatty acids and phenols between treatments(P> 0.05). The results indicate that phytase has greater benefits when formulated using nutrient matrix values as compared with adding it over the top in an already nutrient sufficient diet. The later method would be expected to increase feed costs without concomitant performance benefits.

Bacillus amyloliquefaciens CECT 5940 improves performance and gut function in broilers fed different levels of protein and/or under necrotic enteritis challenge

Two studies were conducted to investigate the effect of Bacillus amyloliquefaciens CECr 5940(BA)as a probiotic on growth performance,amino acid digestibility and bacteria population in broiler chickens under a subclinical necrotic enteritis(NE)challenge and/or fed diets with different levels of crude protein(CP).Both studies consisted of a 2×2 factorial arrangement of treatments with 480 Ross 308 mix-sexed broiler chickens.In study 1,treatments included 1)NE challenge(+/),and 2)BA(1.0×106 CFU/g of feed)supplementation(+/-).In study 2,all birds were under NE challenge,and treatments were 1)CP level(Standard/Reduced[2%less than standard])and 2)BA(1.0×106 CFU/g of feed)supplementation(+/-).After inducing NE infection,blood samples were taken on d 16 for uric acid evaluation,and cecal samples were collected for bacterial enumeration.In both studies,ileal digesta was collected on d 35 for nutrient digestibility evaluation.In study 1,the NE challenge reduced body weight gain(BWG),supressed feed conversion ratio(FCR)and serum uric acid levels(P<0.001).Supplementation of BA increased BWG(P<0.001)and reduced FCR(P=0.043)across dietary treatments,regardless of challenge.Bacillus(P=0.030)and Ruminococcus(P=0.029)genomic DNA copy numbers and concentration of butyrate(P=0.017)were higher in birds fed the diets supplemented with BA.In study 2,reduced protein(RCP)diets decreased BWG(P=0.010)and uric acid levels in serum(P<0.001).Supplementation of BA improved BWG(P=0.001)and FCR(P=0.005)and increased Ruminococcus numbers(P=0.018)and butyrate concentration(P=0.033)in the ceca,regardless of dietary CP level.Further,addition of BA reduced Clostridium perfringens numbers only in birds fed with RCP diets(P=0.039).At d 35,BA sup-plemented diets showed higher apparent ileal digestibility of cystine(P=0.013),valine(P=0.020),and lysine(P=0.014).In conclusion,this study suggests positive effects of BA supplementation in broiler diets via modulating gut microflora and improving nutrient uptake.

An early feeding regime and a high-density amino acid diet on growth performance of broilers under subclinical necrotic enteritis challenge

Broilers that have early access to feed have been shown to have enhanced immune system and gut development and heightened resilience against necrotic enteritis(NE). This study examined the effect of early feeding a high amino acid density diet on performance of broilers under a sub-clinical NE challenge model. Ross 308 broilers(n = 576) were assigned to a 2 × 2 × 2 factorial design with 2 feeding regimes(feed access either within 6 h post-hatch or after 48 h post-hatch), 2 diets(control diet or the control diet with an additional 10% digestible amino acids [HAA]) and either presence or absence of NE challenge.Oral administrations of Eimeria species(d 9) and a field strain of Clostridium perfringens(d 14) were used to induce NE, Broiler performance was analysed at d 13.23.30 and 35, Intestinal lesion score and bacterial count were analysed on d 16. The NE challenge reduced overall bird performance and induced severe intestinal lesions, without causing notable mortality. At d 23 bird weight was significantly lower(P < 0.001) in the challenged birds compared with the unchallenged birds, but by d 30 the challenged birds had recovered and challenge no longer had an impact on bird performance. Birds fed the HAA diet had greater body weight by d 35 and heightened Lactobacillus content in the ileum at d 16(P < 0.05).Birds that were fed the HAA diet after a period of fasting performed better in terms of feed conversion ratio(FCR) under challenge. The findings from this study suggest there are beneficial effects of feeding high amino acid diets to birds in response to external stresses, such as post-hatch fasting and subclinical NE.

Multi-carbohydrase enzymes improve feed energy in broiler diets containing standard or low crude protein

This study evaluated the effect of multi-carbohydrase(MC)on energy and nitrogen(N)balance and gene expression in broilers fed diets with different crude protein(CP)contents.The study employed a 2×2 factorial arrangement of treatments.The factors were presence or absence of MC,and standard(SCP)or low(LCP)dietary CP concentration.A 3-phase feeding program was used,including starter(0 to 7 d),grower(8 to 17 d)and finisher(18 to 28 d)phases.The study was undertaken in closed calorimetry chambers.Each of the 4 dietary treatments was replicated 8 times in total across 2 runs,with 2 birds per replicate(n=64).Data for energy partitioning and N balance were collected from d 25 to 28.On d 28,birds were euthanized to collect muscle and intestinal tissue samples for gene expression.The results showed that the MC increased apparent metabolizable energy(AME,P<0.01)and net energy(NE,P<0.05),and reduced the feed conversion ratio(FCR,P<0.01)in all diets.The proportion of energy retained as fat per total energy retention(REf/RE)was positively correlated with feed AME and NE(r=0.541,P<0.01 and r=0.665,P<0.001,respectively),suggesting that feed energy augmented with increased fat gain.Muscle ATP synthase subunit alpha(ATPSA1W)gene expression had a positive cor-relation with REf/RE and feed NE(r=0.587,P<0.001 and r=0.430,P<0.05,respectively).Similarly,muscle peroxisome proliferator-activated receptor gamma coactivator 1 alpha(PGC-1A)expression was negatively correlated with weight gain and positively correlated with FCR(r-0.451,P<0.05 and r-0.359,P<0.05,respectively).These correlations show that over-expressions of muscle genes related to energy production reduce bird performance.This study demonstrated that MC increase dietary energy utilization,regardless of dietary CP concentration.However,the energy released by the enzymes in-creases feed energy-to-CP ratio,meaning there is excess energy that is then deposited as body fat.This suggests that supplemental MC in broiler feeds is beneficial if diets are formulated to contain marginal energy levels.

Abductive statistical methods improve the results of calibration curve bioassays:An example of determining zinc bioavailability in broiler chickens

In this paper,we discuss the theory behind calibration curve experiments and their application to a zinc(Zn)bioavailability study with broiler chickens.Seven replicates of 16 male commercial broiler chicks were fed starter diets for 14 days.Six diets had different levels of a potential Zn source and one was a positive control with standard industry levels of Zn for comparison.Four commonly used methods of calculating bioavailability means and confidence intervals(CI)from a calibration curve(standard curve)experiment to estimate the bioavailability of a new zinc source in broiler chickens were compared.The methods compared were the following:1)the Counter-Intuitive Method uses a multiple-range test to compare unknown test and standard samples;2)the Intuitive Method uses standard linear regression and inverts the equation to predict Zn bioavailability for each replicate of test samples;3)the Abductive Method uses Graybill's Equation,based on theory and observation,to estimate CI's;and 4)the Sophistic Method uses reverse regression,and calculates Zn bioavailability values directly from the equation.The Counter-Intuitive Method only gives information about which standards the test samples are,or are not,significantly different from respectively(average available Zn not predicted).The Intuitive Method ignores error about the standard curve and theoretically cannot estimate the CI directly(X±SEM=107.5±15.8 mg Zn/kg).The Sophistic Method underestimates and overestimates the test sample mean values above and below the mean of the standards,respectively(X=96.6 mg Zn/kg).The Abductive Method has an advantage over the other methods:The mean prediction estimation is consistent with theory(107.5±6.1 mg Zn/kg;X±SEM).When test or“unknown”samples are near the mean of the standard samples,the CI is smaller than when near the extremes of the calibration curve.When calibration curve error is small(R^(2)>approximately 0.95),there is little advantage to using the Abductive Method,but when calibration curve error is larger,as in many bioassays with growing animals,the Abductive Method improves the accuracy of the CI calculations.The Abductive Method was used to demonstrate the influence of the number of replicate samples on experimental power and cost.