Bacillus subtilis and yeast cell wall improve the intestinal health of broilers challenged by Clostridium perfringens

1. The objective was to investigate the effects of Bacillus subtilis, yeast cell wall (YCW) and their combination on intestinal health of broilers challenged by Clostridium perfringens over a 21-d period.

2. Using a 5 × 2 factorial arrangement of treatments, 800 1-d-old male Cobb 500 broilers were used to study the effects of feed additives (without additive or with zinc bacitracin, B. subtilis, YCW, and the combination of B. subtilis and YCW), pathogen challenge (without or with Clostridium perfringens challenge), and their interactive effects.

3. C. perfringens infection increased intestinal lesions scores, damaged intestinal histomorphology, increased serum endotoxin concentration, cytokine mRNA expression and intestinal population of C. perfringens and Escherichia coli and decreased ileal bifidobacteria numbers. The 4 additives decreased serum endotoxin. Zinc bacitracin tended to decrease cytokine mRNA expression and the intestinal number of C. perfringens and E. coli. B. subtilis, YCW and their combination increased cytokine mRNA expression. B. subtilis and YCW decreased the number of C. perfringens and E. coli in the ileum, and their combination decreased pathogens numbers in the ileum and caecum.

4. In conclusion, B. subtilis, YCW and their combination improved the intestinal health of NE-infected broilers, and could be potential alternatives to antibiotics.     

凝结芽孢杆菌对感染产气荚膜梭菌肉鸡生长性能、肠道病变及免疫器官指数的影响

本试验旨在研究日粮中添加凝结芽孢杆菌对感染产气荚膜梭菌肉鸡生长性能、肠道病变及免疫器官指数的影响。选用312只1日龄科宝500肉鸡公雏,随机分成4个处理,每个处理6个重复,每个重复13只鸡。采用2×2双因子完全随机设计,产气荚膜梭菌分为无感染产气荚膜梭菌组和感染产气荚膜梭菌组,日粮中凝结芽孢杆菌水平分别为0和400mg/kg。试验期35d。结果表明,感染产气荚膜梭菌后15~35日龄肉鸡平均日增重显著降低(P0.05),28日龄肠道病变严重(P0.01),35日龄法氏囊指数极显著降低(P0.01);日粮中添加凝结芽孢杆菌可显著提高15~35日龄肉鸡平均日增重(P0.05),显著降低料重比(P0.05),能缓解感染导致的肠道损伤(P0.05),28日龄肉鸡胸腺指数极显著提高(P0.01),35日龄法氏囊指数极显著提高(P0.01)。肠道病变结果分析表明,日粮中添加凝结芽孢杆菌与感染产气荚膜梭菌有显著交互作用(P0.05)。综上所述,日粮中添加凝结芽孢杆菌能够提高感染产气荚膜梭菌肉鸡生长性能及免疫器官指数,增强动物免疫能力,并能缓解由于产气荚膜梭菌感染而导致的不利影响。     

Growth and meat yield responses of Ross × Ross 708 male broilers fed diets formulated with distillers dried grains with solubles varying in ether extract content and inclusion rate from 1 to 49 days of age

An experiment was conducted to evaluate the effects of diets containing low-, moderate-, or high-oil dried distillers dried grains with solubles (DDGS) included at conventional- or increased-inclusion rates fed to 1,500 Ross × Ross 708 male broilers that were assigned to 60 floor pens from 1 to 49 d of age. Three sources of DDGS had ether extract composition of 6.06, 8.80, or 11.59%, on dry matter (DM) basis, representing low-oil, moderate-oil, or high-oil DDGS, respectively. Diets were formulated to contain corn, soybean meal, animal protein meal as the primary ingredients, and 1 of the 3 DDGS sources at either 5, 7, 9, or 11% (conventional-inclusion rate) and 8, 10, 12, or 14% (increased-inclusion rate) in the starter (1 to 14 d), grower (15 to 24 d), finisher 1 (25 to 34 d), and finisher 2 (35 to 49 d) periods, respectively. Apparent ME_n (low-oil:1,975, moderate-oil: 2,644, and high-oil: 3,137 kcal/kg) and digestible amino acid (AA) values of the 3 DDGS sources were determined from previous research. No differences were detected for cumulative BW gain and feed conversion 1 to 49 d of age or meat yields at 50 d of age. Feeding broilers diets containing the low-oil DDGS source increased feed cost per BW gain and breast meat weight of $0.025/kg and $0.004/kg compared with birds fed diets containing high-oil DDGS or moderate-oil and high-oil DDGS sources, respectively. These data indicated that DDGS source and inclusion rate did not affect cumulative growth and carcass characteristics of broilers from 1 to 50 d of age but demonstrate differences in feed cost/BW gain and feed cost/breast meat weight.     

Dietary hydrolysed yeast cell wall extract is comparable to antibiotics in the control of subclinical necrotic enteritis in broiler chickens

ABSTRACT

1. The aim of this study was to examine the effect of yeast cell wall (YCW) on performance and physiological responses of broiler chickens under subclinical necrotic enteritis challenge.

2. Six treatments in a 2 × 3 factorial arrangement (non-challenged or challenged plus no supplement, YCW or antibiotics (AB)) was used. Each treatment was replicated eight times with 12 birds per replicate. The treatments included: (1) Positive control (PC; no additive, not challenged); (2) Negative control (NC; no additive, with challenge); (3) YCWN = yeast cell wall (2.0 g/kg diet, not challenged; (4) YCWC = yeast cell wall (2.0 g/kg diet, challenged); (5) ABN = zinc bacitracin 50 ppm + Salinomycin 60 ppm, not challenged); (6) ABC = zinc bacitracin 50 ppm + Salinomycin 60 ppm, challenged).

3. Eimeria challenge at 9 d of age did not affect feed intake (FI), body weight gain (BWG), FCR or liveability at 10 d. The BWG and FCR at 10 d were greater (P < 0.05) in birds fed YCW or AB (AB) diets relative to the PC or NC groups. On 24 and 35 d, FI, BWG, FCR and flock uniformity (28 d) were greater (P < 0.05) in the challenged groups fed YCW or AB diets compared to NC group.

4. Supplementation with YCW ameliorated the negative effects of NE on liver, spleen and bursa weight of birds.

5. Necrotic enteritis challenge decreased (P < 0.05) caecal Lactobacillus and Bifidobacterium spp. counts, and increased ileum lesion score and caecal Clostridium perfirngens counts. This was reversed by the addition of either YCW or AB.

6. Supplementation with YCW and AB resulted to a greater (P < 0.05) dressing percentage and meat yield (35 d).

7. The results indicated that YCW plays a vital role in improving the physiological response and performance of broiler chickens under subclinical necrotic enteritis challenge.     

Organic acid blend in diets of broiler chickens challenged with Clostridium perfringens

This study was conducted to evaluate the effects of a blend of organic acids (OAs) in diets with or without antibiotic growth promoter (AGP) in chickens challenged with Clostridium perfringens. Day-old male broiler chicks were used in a trial with 4 treatments and 6 replicates of 50 birds per pen, for 43 days, in a completely randomized design. The treatments in a 2×2 factorial arrangement consisted of the presence or absence of enramycin (AGP) and of a blend of OA in the feed. All birds were inoculated at 7 days of age with an anticoccidial vaccine in the drinking water; on days 14, 15, and 16, they were inoculated with C. perfringens in the feed. OA improved weight gain, body weight, and feed intake in the periods 1–7 days and 1–21 days in chicks without antibiotic supplementation. The AGP had the main effect of increasing weight gain and body weight at 35 d; the OA increased weight gain, body weight, and feed intake at 43 days of age. The birds supplemented with OA without AGP had a higher number of CD3+ cells in the ileum mucosa and lower crypt depth than birds supplemented with both OA and antibiotic at 7 days. At 21 days of age, birds fed OA without AGP had higher villus height and a larger villus/crypt ratio; however, there were no differences in the CD3+ cells in the ileal mucosa. The use of OA was beneficial for weight gain and AGP for feed conversion, and the combination of OA and AGP brings complementary advantages in production.     

The effects of strain and incremental improvements in feed form on d 28 to 42 male broiler performance

Feeding high-quality pellets to modern commercial broilers may maximize genetic potential; however, this typically requires an increased cost to produce feed. Therefore, it is important to determine if incremental improvements in feed form (FF) can increase performance of modern broiler strains. The current study was conducted to investigate the effects of feeding modest improvements in feed form (50, 60, 70, or 80% intact pellets; IP) to 2 commercial broiler strains (fast-growing or high-yield) on d 28 to 42 growth performance and processing variables. A common diet was manufactured to contain 80% IP, of which a portion was ground to create a total of 4 FF treatments varying in IP to ground pellet ratios: 50:50; 60:40; 70:30; and 80:20. Fast-growing (FG) birds demonstrated improvements in body weight (BW), BW gain (BWG), and feed conversion ratio (FCR) when compared to high-yield (HY) birds. For the main effect of FF, feeding 80 vs. 50% IP reduced d 28 to 42 FCR. Also, feeding birds 80% IP vs. all other FF treatments improved d 28 to 42 BWG and d 42 BW. A Strain × FF interaction established that FG broilers fed 50, 60, and 70% IP diets had higher d 43 total breast yield than HY birds fed the same FF treatments; however, both strains demonstrated similar total breast yield when 80% IP were fed, which suggests that FG broilers are less sensitive and HY broilers are more sensitive to increasing FF. These data suggest a distinct benefit for feeding improved FF from d 28 to 42 to modern broilers.     

Potential of a mixture of eugenol and garlic tincture to improve performance and intestinal health in broilers under necrotic enteritis challenge

Plant extracts(PE)are gaining increased attention as potential alternatives to in-feed antimicrobials(AM)due to their known antimicrobial activities.This study was conducted to examine the potential of PE,a microencapsulated product composed of eugenol and garlic tincture as an alternative to AM-agent on performance and intestinal health in broilers under necrotic enteritis(NE)challenge.A total of 960 dayold mixed-sex Cobb 500 chicks were randomly distributed to 48-floor pens with 6 treatments replicated 8 times with 20 birds each.The 6 treatments were as follows:UC,unchallenged control;CC,challenged control;PE,challenged group plus PE;AM,challenged group plus AM;FAP,challenged group plus a full dose of AM with PE;HAP,challenged group plus a half dose of AM with PE in starter,grower and finisher phases.Birds in the challenged groups were inoculated with Eimeria spp.on d 9 and Clostridium perfringens on d 14.The body weight gain(BWG),feed intake(FI),feed conversion ratio(FCR),and livability of birds were compromised,and intestinal lesions and mortality were increased(P<0.05)by NE challenge,illustrating a successful clinical NE challenge.Birds fed AM had higher BWG and FI,and lower FCR,mortality,and intestinal lesions compared to the CC group(P<0.05).Birds fed PE had improved FCR(P<0.05)and livability(5.8%)in an overall period compared to the CC group.On d 16,PE supplementation reduced ileal lesion scores in only male birds(P<0.05).Birds fed PE had decreased Eimeria maxima and Eimeria acervulina oocyst counts in caecal content(P<0.05).Birds fed PE had decreased Eimeria brunetti and total oocyst counts in caecal content,and E.acervulina oocyst counts in ileal content in only female birds(P<0.05).On d 35,PE supplementation reduced variation of BW in both male and female birds and increased yellowness(b*value,14.4%)in the thigh.These findings suggest the potential of PE supplementation in diets to improve the performance and intestinal health of birds under clinical NE as indicated by improved FCR,livability,uniformity,reduced ileal lesions,oocyst counts and increased skin yellowness.However,the protective effect of PE may not be apparent in the presence of AM in the feed.     

Anise oil dosage and its effect on growth performance and jejunal lesions during a Clostridium perfringens challenge in battery trials,and growth performance in a floor pen trial,

Anise oil (AO) is a phytochemical with antibiotic properties and it reduces the growth of Clostridium perfringens in vitro, which is the main causal agent of necrotic enteritis. A series of battery experiments was conducted to determine an AO dosage to feed to broilers and its effect during 2 C. perfringens challenges, and a floor pen experiment to determine its effect in performance. Anise oil linearly reduced (P < 0.05) ADFI and ADG, but feeding broilers 500 to 2,000 mg/kg of AO resulted in similar performance with positive control (PC) fed broilers. Broilers were challenged on d 10 (Experiment 2) or on d 10 and 13 (Experiment 3). Broilers fed AO had lower (P < 0.05) ADFI and ADG compared with broilers fed PC from zero to 18 d (Experiment 2). Growth performance of broilers fed AO was not affected (P > 0.05) during Experiment 3. In both challenges, the jejunum of broilers fed AO had fewer and milder (P < 0.05) lesions compared with broilers fed PC or negative control (NC) diets. In a floor pen trial, 1,000 mg/kg of AO was fed to broilers from zero to 42 days. Broilers fed AO or PC had similar (P > 0.10) growth performance for the entire trial. Broilers fed PC or AO had greater ADG (P < 0.05) and tended (P = 0.07) to be heavier than broilers fed NC at the end of the trial. Breast yield percentage was similar (P > 0.10) among broilers fed any of the dietary treatments. Residues of AO were not present at detectable levels in breast meat.     

Effect of multi-enzymes in combination with a direct-fed microbial on performance and welfare parameters in broilers under commercial production settings

The objective of this study was to determine the response of broilers to the combination of multi-enzymes and direct-fed microbial (DFM) under commercial production settings. A total of 7,000 1-day-old male broilers (Ross 308) were distributed over 10 pens (700 broilers/pen). Two dietary treatments were tested using complete randomized design, including a control diet and a test diet with addition of multi-enzymes (xylanase, amylase, and protease (XAP)] and DFM (a combination of spores from 3 strains ofBacillus amyloliquefaciens). Pelleted diets were offered ad libitum in 3 phases and water was freely available. During starter and grower phases (0 to 21 d), the enzyme and DFM combination resulted in improved FE (P < 0.05). During the finisher phase, higher feed intake and BW gain (P < 0.05) were observed for the test group. Overall, there were significantly higher feed intake, BW gain, and lower water-to-feed ratio in test group compared to the control group. This was related to improved (P < 0.05) modified production efficiency factor which was calculated based on final BW, survival rate, feeding period, and mortality-weight-corrected FCR. The test group had improved litter quality and a reduced foot-pad lesion score compared to the control. In addition, there was a tendency (P < 0.1) of reducingClostridium perfringens population in cecal digesta and higher lactic acid content in the ileal digesta, when expressed on an as-is basis, in the test group. In this study, we demonstrated that using a multi-enzymes and DFM combination in the diet for broilers can result in improved FE in starter/grower phases and animal welfare parameters, and lead to improved production efficiency under commercial settings.     

Growth Responses of Male Broilers Subjected to High Air Velocity for either Twelve or Twenty-Four Hours from Thirty-Seven to Fifty-One Days of Age

Heat stress contributes to increased late-mortality and decreased growth of broilers grown during hot weather. Tunnel ventilation is commonly used to alleviate heat stress by increasing sensible heat loss. As broilers approach heavy BW (>2.5 kg) in hot weather, operating tunnel ventilation continuously as opposed to only during times of high ambient temperature may improve growth rate and nutrient utilization. This study evaluated growth responses of male broilers subjected to high air velocity (2.79 m/s) for either 12 or 24 h from 37 to 51 d of age. The experimental treatments were 1) control (still air), 2) air velocity of 1.65 m/s (325 ft/min) for 12 h and 2.79 m/s for 12 h, and 3) air velocity of 2.79 m/s (550 ft/min) for 24 h. A cyclical temperature regimen of 25–30–25°C (77–86–77°F) was used with a constant 23°C dew point.Providing continuous high air velocity of 2.79 m/s from 37 to 51 d of age led to a 112-g increase in BW gain and decreased feed conversion ratio by 15 points compared with subjecting broilers to high air velocity of 2.79 m/s for only 12 h. Broilers subjected to both high and low air velocity improved BW gain, feed consumption, and feed conversion over the control birds. These results indicate that continuous ventilation at high air velocity improves BW gain and feed conversion ratio of heavy broilers during the last 2 wk of the grow-out.     

Optimization of surfactin production from Bacillus subtilis in fermentation and its effects on Clostridium perfringens‐induced necrotic enteritis and growth performance in broilers

Bacillus species are commonly used as probiotics in the poultry feed industry for preventing infectious diseases and improving productivity by altering gastrointestinal microbiota. The growth parameters of Bacillus subtilis for surfactin production in fermentation and the benefits of surfactin on broiler chickens remain unclear. In this study, we examined the growth parameters of B. subtilis in fermentation and evaluated the effects of surfactin from B. subtilis‐fermented products on Clostridium perfringens‐induced necrotic enteritis and growth performance in broilers. Results showed that the highest viable biomass of B. subtilis was observed at 10% molasses and 2% yeast supplementation during fermentation. The 4‐ and 6‐day fermented B. subtilis products were heat‐, acid‐ and bile‐resistant. Furthermore, the 4‐day fermented B. subtilis products with the highest surfactin concentration showed the maximal antimicrobial activity against pathogens, including Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and C. perfringens. Dietary B. subtilis‐fermented product supplementation in broilers significantly improved intestinal morphology and necrotic lesions under C. perfringens challenge. Bacillus subtilis treatments could enhance broiler productivity, as well as promote bone quality and intestinal morphology. These results together indicate that B. subtilis‐fermented products containing surfactin have potential for the development as feed additives and use as possible substitutes for antibiotics to treat C. perfringens in the poultry industry.     

Effect of Dietary Mannan Oligosaccharide (Bio-Mos) on Live Performance of Broiler Chickens Given an Anticoccidial Vaccine (Paracox) Followed by a Mild Coccidial Challenge

A pen trial with 720 Ross 308 male chicks evaluated effects of Paracox-5 vaccination at d 1, dietary mannan oligosaccharide (MOS; Bio-Mos at 2, 1, and 0.5 kg/tonne in starter, grower, and finisher, respectively), and d-15 Eimeria challenge on d-22 lesions and 1 to 42-d live performance. Available floor area in each of 24 floor pens was 2.1 m², and 30 chicks were placed per pen initially. A 3-phase feeding program was used: starter (0 to 15 d), grower (16 to 22 d), and finisher (23 to 42 d). The 4 dietary and vaccine treatments were as follows: 1) without vaccination, dietary MOS, or coccidiosis challenge; 2) without vaccination and dietary MOS but with a 3-strain pathogenic Eimeria challenge; 3) with Paracox-5 vaccination and Eimeria challenge but no dietary MOS; and 4) with Paracox vaccination, dietary MOS, and Eimeria challenge. The pathogenic Eimeria sporulated oocysts mixture from the French National Institute for Agricultural Research (Paris, France), standardized and well-defined, was given via feed at d 15 (100,000 Eimeria acervulina, 10,000 Eimeria maxima, and 15,000 Eimeria tenella per bird). Coccidiosis lesion scores were recorded at 22 d of age (scored as 0, 1, 2, or 3 with increasing severity). Overall mean lesion scores (P < 0.001) were higher in challenged birds. Paracox-5 alone improved 15-d BW and 1 to 15- and 15 to 22-d average daily gain of Eimeria-challenged broilers (P < 0.05). Dietary MOS improved (P < 0.05) 15 to 42- and 22 to 42-d FCR of Paracox-5 vaccinated, Eimeria- challenged broilers. Mortality was 4.4 to 5.8% by treatment, with no significant differences. It was concluded that dietary MOS improved the feed conversion ratio of Paracox-5-vaccinated (d 1), challenged (d 15) broilers from 15 to 42 d of age.     

Effect of Spray-Dried Plasma Form and Duration of Feeding on Broiler Performance During Natural Necrotic Enteritis Exposure

The effect of duration of feeding (continuous or discontinued after d 14) and form (granular vs. powder) of spray-dried plasma (SDP) on performance and mortality of broilers using used litter was evaluated with 240 Ross × Ross 308 male broilers (6 broilers per pen, 8 pens per treatment). Dietary treatments were control (no SDP) or SDP as powder or granular included in the pellet and fed continuously (d 0 to 35) or discontinued after d 14. During the experiment, broilers developed necrotic enteritis, and tissue cultures were positive for Escherichia coli and Salmonella, resulting in 50% mortality on control broilers. Addition of SDP to the feed improved (P < 0.05) average daily gain, feed intake, and feed efficiency for each period of the study (d 0 to 14, 15 to 28, 29 to 35, and 0 to 35). Continuous feeding of SDP improved (P < 0.05) average daily gain, feed intake, and feed efficiency from d 15 to 35 compared with broilers fed SDP to d 14. Liveability was improved (P < 0.05) in broilers consuming SDP either for 14 d or continuously throughout the experiment compared with control broilers. Spray-dried granular plasma was more effective than spray-dried powder plasma from d 0 to 14. The results of this experiment confirmed that SDP improved broiler growth rate, feed intake, feed efficiency, and minimized enteric challenge associated with necrotic enteritis with maximal protection afforded by continuous feeding. The response to SDP was independent of age of the broiler.     

Effects of Mannanoligosaccharide on Growth Performance,the Development of Gut Microflora,and Gut Function of Broiler Chickens Raised on New Litter

In search of substances to replace antibiotics as growth promoters for farm animals, mannanoligosaccharides (MOS) have been proposed as a possible alternative. In the present experiment, the influence of MOS on growth performance and bacteriological, morphological, and functional aspects of small intestine was investigated in broiler chickens at different ages. Three dietary treatments were used: a negative control without MOS or antibiotic, a positive control (Zn bacitracin), and 2 g of MOS/kg of diet. The MOS supplement tended to improve BW gain compared with the negative control in early life (P = 0.07). The counts of total anaerobic bacteria, lactic acid bacteria, and Clostridium perfringens were not affected by the supplementation of MOS. The counts of coliform bacteria were increased in young birds treated with MOS. No significant differences in the gut morphology and function were noticed between the MOS treatment and the negative or the positive control at d 14, but birds in the positive control group had significantly higher jejunal villi and mucosal alkaline phosphatase activities than MOS-supplemented birds at d 35. In the current study conducted under hygienic experimental conditions, the addition of MOS did not show a clear positive effect on performance or intestinal morphology and function.     

Organic acid blends improve intestinal integrity,modulate short-chain fatty acids profiles and alter microbiota of broilers under necrotic enteritis challenge

Controlling enteric diseases of broilers is crucial.Among many additives,organic acids(OA)and their blends are gaining attention to combat diseases in the post-antibiotic era.The current study evaluated the potentials of short-chain fatty acids(SCFA)and medium-chain fatty acids(MCFA)blends and/or phenolic compounds on intestinal integrity,intestinal pH,caecal microbiota,and caecal SCFA profiles of broilers under necrotic enteritis(NE)challenge.The additives used were:(A)a blend of SCFA,MCFA,and a phenolic compound(SMP),(B)a blend of free and buffered SCFA with MCFA(SMF),and(C)a blend of free and buffered SCFA with a high concentration of MCFA(SHM).A total of 1,404 male parental chicks of Ross 308 broilers were randomly allocated to 78 floor pens on hatching day with 6 treatments replicated 13 times with 18 birds per pen.The treatments were:UCC,unchallenged control;CHC,challenged control;BAC,challenged group plus zinc bacitracin;SMP,challenged group plus additive SMP;SMF,challenged group plus additive SMF;SHM,challenged group plus additive SHM.Birds were challenged with field-strain Eimeria spp.on d 9 and Clostridium perfringens on d 14.Birds challenged with NE increased fluorescein isothiocyanate dextran(FITC-d)concentration in serum,reduced acetate and butyrate concentrations,and increased Bacteroides and C.perfringens load in the caeca(P<0.05).Birds fed additives decreased FITC-d from gut to serum,reduced Bacteroides(d 16,P<0.05)and numerically reduced C.perfringens load compared to CHC group.Birds fed additive SHM had higher concentrations of acetate and butyrate(d 21,P<0.05)than CHC group but were not different from SMP and SMF groups.All the additives exhibited similar intestinal protection against NE compared to the BAC group indicated by FITC-d concentration in serum,acetate,propionate and butyrate concentrations in the caeca,and caecal bacterial loads except for the C.perfringens(P>0.05).The SMP group had a higher load compared to BAC(P<0.05).These findings suggest the promising effects of OA blends as alternatives to BAC to ameliorate the impact of NE challenge of broilers as indicated by improved intestinal health.     

The Effects of Photoperiod Length,Light Intensity,and Feed Energy on Growth Responses and Meat Yield of Broilers

A study was conducted to assess the effects of photoperiod length (constant 23L:1D vs. a photoperiod program going from decreasing to increasing quantity of light), light intensity (bright vs. a dim, reducing intensity), and feed ME levels (low vs. high) on performance and carcass characteristics of female broilers grown to 56 d. Use of a treatment with early decreasing photoperiod followed by an increasing photoperiod reduced feed consumption and subsequent BW early. However, growth compensation occurred and feed consumption and BW were similar across photoperiod treatments by study end. Likewise, reducing light intensity (from 1 to 0.25 fc) stimulated feed consumption and a subsequent BW improvement early, as compared with high-intensity (2 fc) lighting maintained at a constant level. However, the disparity in feed consumption and BW, as influenced by light intensity, did not persist throughout the growing period. Feed conversion was not noticeably affected by photoperiod or light intensity treatments. Minimal effects of lighting were observed for carcass or part yields; however, there appeared to be a subtle substitution effect between leg, wing, and breast yield influenced by lighting program. Birds exposed to the decreasing–increasing photoperiod and dim, reducing light treatments yielded more leg and wing at the expense of breast. Feeding a low ME diet resulted in increased feed consumption and feed conversion. However, birds consuming a low ME diet were more uniform. No effects of treatment on mortality were measured. These data indicate that a decreasing–increasing photoperiod can be used effectively to reduce early growth, yet allow birds to compensate as they approach market age. Low intensity lighting, however, appears to stimulate early feed consumption and growth, although this effect is transitory. Furthermore, the increased feed conversion of birds grown on the low energy diet may make its use less desirable.     

Fumonisins affect the intestinal microbial homeostasis in broiler chickens,predisposing to necrotic enteritis

Fumonisins (FBs) are mycotoxins produced by Fusarium fungi. This study aimed to investigate the effect of these feed contaminants on the intestinal morphology and microbiota composition, and to evaluate whether FBs predispose broilers to necrotic enteritis. One-day-old broiler chicks were divided into a group fed a control diet, and a group fed a FBs contaminated diet (18.6 mg FB1+FB2/kg feed). A significant increase in the plasma sphinganine/sphingosine ratio in the FBs-treated group (0.21 ± 0.016) compared to the control (0.14 ± 0.014) indicated disturbance of the sphingolipid biosynthesis. Furthermore, villus height and crypt depth of the ileum was significantly reduced by FBs. Denaturing gradient gel electrophoresis showed a shift in the microbiota composition in the ileum in the FBs group compared to the control. A reduced presence of low-GC containing operational taxonomic units in ileal digesta of birds exposed to FBs was demonstrated, and identified as a reduced abundance of Candidatus Savagella and Lactobaccilus spp. Quantification of total Clostridium perfringens in these ileal samples, previous to experimental infection, using cpa gene (alpha toxin) quantification by qPCR showed an increase in C. perfringens in chickens fed a FBs contaminated diet compared to control (7.5 ± 0.30 versus 6.3 ± 0.24 log10 copies/g intestinal content). After C. perfringens challenge, a higher percentage of birds developed subclinical necrotic enteritis in the group fed a FBs contaminated diet as compared to the control (44.9 ± 2.22% versus 29.8 ± 5.46%).

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0234-8) contains supplementary material, which is available to authorized users.     

Midday and Nighttime Cooling of Broiler Chickens

Hot weather along with high stocking densities can lead to high mortality and decreased performance of broilers, especially during the last week of rearing. Two trials were conducted to test the hypotheses that reduced nighttime and midday temperatures improve broiler live performance and reduce mortality under warm cyclic temperature conditions. In each trial, groups of 306 male broilers were placed in each of 6 environmentally controlled chambers. The warm temperature treatments were control, nighttime cooling, and midday cooling (4 replicates). In the control treatment, diurnal temperatures ranged between 15 and 25°C on d 29 and progressively increased to between 20 and 35°C on d 42. In trial 2, 2 additional chambers housed broilers under thermoneutral conditions. No differences in feed consumption were found within or between trials due to the temperature treatments. The cooling treatments did not improve BW, weight gain, feed conversion, or livability. The birds housed under thermoneutral conditions did not have improved BW. These results suggest that broilers subjected to regular warm cyclic temperature fluctuations for 2 wk prior to shipping are able to acclimatize with no negative impact on BW. Effective environmental temperatures predicted from broiler surface thermal resistance and thermal mass were within 5°C among the treatments.     

Influences of breeder age and fasting after hatching on the performance of broilers

In this trial, we assessed the effects of 2 different ages of breeders and of 2 periods of fasting posthatching on the performance of broilers up to 42 d of age. Male broilers from breeders of different ages (30 and 60 wk) were subjected to an experimental design with 4 treatments: 1) T1, chicks not subjected to fasting, from 30-wk-old breeders; 2) T2, chicks not subjected to fasting, from 60-wk-old breeders; 3) T3, chicks subjected to a 12-h fast, from 30-wk-old breeders; and 4) T4, chicks subjected to a 12-h fast, from 60-wk-old breeders. At the end of the trial, feed intake was greater for the chicks from older breeders. Fasting had a negative influence on feed intake in the period from 0 to 10 d of age. The birds from older breeders had a greater BW gain from 21 to 35 d of age when they were not subjected to a fasting period, but when birds were subjected to a fasting period, no differences between broiler breeder ages were observed on BW gain. Fasting did not exert a significant effect on the BW of the birds. Feed conversion was not influenced by the age of the breeders or by fasting.     

Yeast cell wall and live yeast products and their combination in broiler diets formulated with weekly ingredient variations

A 6‐week broiler study was conducted to evaluate whether subjecting the intestinal microflora of broilers to the effect of weekly variations in feed ingredients could be ameliorated by the inclusion of yeast‐derived feed additives: a yeast cell wall extract (YCW), live yeast culture (LY) or their combination (YCW + LY). Recent changes in ingredient prices have motivated producers to formulate diets not necessarily based primarily on corn and soya bean meal. Intestinal microflora in birds can vary significantly based on the ingredient composition of their diet, and the make‐up of the flora can influence overall bird performance. Within the three nutrient phases of this study, birds were fed either a traditional corn–soya ingredient profile or a variable‐ingredient regimen, which had weekly changes in the ingredient composition. There were consistent ameliorative effects of the yeast treatments in both the corn–soya and the variable‐ingredient groups throughout all 6 weeks, with the YCW + LY combination showing a reduced effect when compared to either product fed alone. The effectiveness of YCW and LY on ameliorating the effects of weekly ingredient variations appeared most effective during the starter and grower phases, but was less significant during the sixth week.