Young Broiler Research Articles

Composition of more specialised pre-starter and starter diets for young broiler chickens: a review

The broiler industry has experienced remarkable improvements in productivity owing to high priority placed on genetic programming, nutrition and management practices. Nutrition of the meat chicken is driven by the need to satisfy the constantly increasing genetic potential, resulting in the shortening of the rearing time required to get the bird to market weight. The concept of feeding broilers a more specialised pre-starter diet for the first 10–14 days of age is gaining interest, as this now accounts for more than 20% of the time for grow-out. Specialised diets may be formulated to be highly digestible or aim to provide specific nutrients at a higher level to meet nutritional requirements of the bird. The effectiveness of specifically formulated pre-starter or starter diets depends on potential carryover effect to increase the bird performance up to the market age. There is evidence that some nutrient requirements of birds, digestible amino acids in particular, in the first 10 days of life may be higher than the current industry recommendation. Among cereals, rice with its lower non-starch polysaccharide content may be a better cereal for pre-starter diets than are corn or wheat. Inclusion of fibrous ingredients in low-fibre diets of young broilers may also stimulate gut development and enhance nutrient utilisation, leading to improved bird performance. There are inconsistencies in responses to various feed additives tested specifically for pre-starter diets of broilers. Finally, with an increasing demand for removal of antibiotic growth promoters from all broiler feeds, focus on formulations to ensure sustainable growth at start will gain importance.

Inclusion of insoluble fiber sources in mash or pellet diets for young broilers. 1. Effects on growth performance and water intake

The effects of feed form and the inclusion of insoluble fiber in the diet on growth performance and water intake were studied in female broilers from 0 to 21 d of age. The experimental design was completely randomized with 14 treatments arranged as a 2 × 7 factorial with 2 feed forms (mash vs. pelleted) and 7 diets that consisted of a control diet low in fiber (1.6% crude fiber) based on broken rice, fermented soybean meal, and fish meal and 6 extra diets that resulted from the inclusion of 3 insoluble fiber sources (oat hulls; OH, rice hulls; RH, and sunflower hulls; SFH) at 2 levels (2.5 vs. 5%). Each treatment was replicated 6 times. Broilers fed pellets had 32% greater ADG and 3% better feed to gain ratio (F:G) than those fed mash (P ≤ 0.001). The inclusion of the fiber sources improved ADG (P ≤ 0.05) and F:G (P ≤ 0.05). Pelleting increased (P ≤ 0.001) water intake from 6 to 8 d, water-to-feed intake ratio from 18 to 20 d, and moisture content of the excreta at 20 d of age. The inclusion of the insoluble fiber sources increased water intake (P ≤ 0.05) from d 18 to 20 but not from d 6 to 8. Increasing the level of fiber inclusion from 2.5 to 5.0% tended to increase (P = 0.086) moisture content in the excreta at d 20. Pelleting and the inclusion of insoluble fiber sources improved ADG and F:G in broilers fed low-fiber diets, and the improvements observed were more pronounced with pellets than with mash. Growth performance of young broilers improves with the addition of moderate amounts of structural insoluble fiber in the diet, regardless of feed form. The inclusion of OH or SFH into low fiber diets was more beneficial for improving broiler performance than the inclusion of RH.

Vocalisation sound pattern identification in young broiler chickens

In this study, we describe the monitoring of young broiler chicken vocalisation, with sound recorded and assessed at regular intervals throughout the life of the birds from day 1 to day 38, with a focus on the first week of life. We assess whether there are recognisable, and even predictable, vocalisation patterns based on frequency and sound spectrum analysis, which can be observed in birds at different ages and stages of growth within the relatively short life of the birds in commercial broiler production cycles. The experimental trials were carried out in a farm where the broiler where reared indoor, and audio recording procedures carried out over 38 days. The recordings were made using two microphones connected to a digital recorder, and the sonic data was collected in situations without disturbance of the animals beyond that created by the routine activities of the farmer. Digital files of 1 h duration were cut into short files of 10 min duration, and these sound recordings were analysed and labelled using audio analysis software. Analysis of these short sound files showed that the key vocalisation frequency and patterns changed in relation to increasing age and the weight of the broilers. Statistical analysis showed a significant correlation (P<0.001) between the frequency of vocalisation and the age of the birds. Based on the identification of specific frequencies of the sounds emitted, in relation to age and weight, it is proposed that there is potential for audio monitoring and comparison with ‘anticipated’ sound patterns to be used to evaluate the status of farmed broiler chicken.

Effect of Post Hatch Delayed Access to Feed on Performance, GIT Physical and Histological Development and Yolk Absorption in Young Broiler Chicks

Introduction In commercial broiler farm, it has been shown that the neonatal chicks remain approximately 24- 36h without feed and water after removal from the incubator until placement in the farm (Bhuiyan et al. 2011; Willemsen et al. 2010), this gap between hatching time and neonatal chick’s

Effect of dietary fibres on small intestine histomorphology and lipid metabolism in young broiler chickens.

Two experiments were conducted to determine the influence of dietary fibres on small intestine histomorphology and lipid metabolism in broilers from 1 to 21 day of age. In experiment 1, diets containing insoluble [cellulose (CEL); 2% and 4%] or soluble [carboxymethyl cellulose (CMC); 2% and 4%] fibre were fed to broilers from day 1 to 21 post-hatch and ileal tissue was collected at day 21 of age for histological evaluation. In experiment 2, broilers diet was supplemented with 0%, 1% or 2% insoluble fibre (Arbocel) during day 7 to 21 post-hatch and plasma and liver lipid metabolism were evaluated at day 21. In experiment 1, inclusion of CMC reduced body weight gain (BWG) and feed intake (FI) and increased feed conversion ratio (FCR) compared with others. Intestinal histomorphology was unaffected by CEL, but CMC led to an increase in crypt depth (CD) and serosa thickness and a decrease in villus height (VH), villus width (VW), VH:CD ratio and villus surface area (VSA), rather than control and CEL groups. Treatment did not affect goblet cell type. Moreover, the CMC-fed birds had greater total goblet cell count (GCC) as compared with others. In experiment 2, fibre inclusion was associated with increases in BWG from 7 to 14 day of age and an improvement in FCR, whereas FI was not influenced by treatments. Inclusion of fibre in the diet decreased the weight of the abdominal fat and cholesterol concentrations of liver and plasma. No significant effects on fatty acid composition of liver lipid were observed by fibre supplementation. These findings suggest dietary fibre affects performance, intestinal histomorphology and lipid metabolism in young chicks, which may directly affect poultry feeding strategies.

Effects of aqua agar as water replacement for posthatch chicks during transportation on residual yolk-sac and growth performance of young broiler chickens.

Water is one of the most essential nutrients for the maintenance of chicks' function, and delayed access to feed and water post hatch has been reported to dehydrate chicks. Aqua agar (AA) was formulated to contain more than 95% water and an experiment was conducted to evaluate the effects of AA as water replacement for posthatch chicks during transportation. During the simulated transport, chicks were held for 24 h with (AA group) or without (NO-AA group) aqua agar in chick boxes. During the holding period, chicks in the AA group lost less body weight, compared with the NO-AA group. However, the weight of residual yolk tended to be lower in the AA-treated birds. There were no significant differences in the weight of gizzard, proventriculus, and liver, nor in the weights and lengths of the duodenum, jejunum and ileum. A higher body weight was also observed in the AA group at 7 days of age. At 21 days of age, weight gain and feed intake were higher (P < 0.05) in the AA group, when compared to that of the NO-AA group. No significant differences were observed in the feed conversion rate (FCR) between the two groups. In conclusion, the data suggests that the use of AA as a water replacement could reduce the negative impact of water deficiency in posthatch period during transportation, resulting in greatly improved growth performance of young broilers at 21 days of age.

The effects of food-related environmental complexity on litter directed behaviour, fear and exploration of novel stimuli in young broiler chickens

Stimulation of foraging behaviour during the first weeks of life by increasing environmental complexity such as scattering food items on the litter may be one way of preventing leg disorders, reducing fear and improving broiler welfare. However, studies on effects of access to various food based enrichment are inconclusive. Motivation of animals to search for resources in the litter may be driven by the motivational significance of the provided food resource. This study was conducted to test whether the motivational significance of food enrichment differentially affects activity, litter directed behaviours and fearfulness in broiler chickens. Chickens (120 chickens in three batches of 40 animals) were divided into four groups according to type of food-related enrichment: (1) mealworms (highly attractive), (2) whole wheat (less attractive), (3) wood shavings (no nutritional value), and (4) no enrichment. Enrichment materials were scattered on the litter daily for 12 days starting on day 6. On days 6, 9, 12 and 15 of age the chickens were video-recorded from 10min before to 30min after scattering. Duration and frequency of physical activity (time spent on legs), litter directed behaviour (litter pecking and scratching) and leg stretching were analysed from videos in 10-min intervals. All birds were subjected to a tonic immobility test (day 16) and a novel object test (day 17). Mealworm treatment induced a significant increase in activity, litter pecking and litter scratching (p<0.001) during the first 10min interval after the treatment. There were no effects on activity, litter directed behaviour, and on any of the parameters in the tonic immobility test and novel object test. In conclusion, motivational significance of the food items scattered on the litter affect litter directed behaviours in broiler chickens. More studies are needed to develop feasible attractive food enrichments and complex distribution methods that would increase time spent in activity.

Genome Analysis of Staphylococcus agnetis, an Agent of Lameness in Broiler Chickens.

Lameness in broiler chickens is a significant animal welfare and financial issue. Lameness can be enhanced by rearing young broilers on wire flooring. We have identified Staphylococcus agnetis as significantly involved in bacterial chondronecrosis with osteomyelitis (BCO) in proximal tibia and femorae, leading to lameness in broiler chickens in the wire floor system. Administration of S. agnetis in water induces lameness. Previously reported in some cases of cattle mastitis, this is the first report of this poorly described pathogen in chickens. We used long and short read next generation sequencing to assemble single finished contigs for the genome and a large plasmid from the chicken pathogen. Comparison of the S. agnetis genome to those of other pathogenic Staphylococci shows that S.agnetis contains a distinct repertoire of virulence determinants. Additionally, the S. agnetis genome has several regions that differ substantially from the genomes of other pathogenic Staphylococci. Comparison of our finished genome to a recent draft genome for a cattle mastitis isolate suggests that future investigations focus on the evolutionary epidemiology of this emerging pathogen of domestic animals.

A trend analysis of antimicrobial resistance in commensal Escherichia coli from several livestock species in Belgium (2011–2014)

A temporal trend analysis was performed on antimicrobial resistance data collected over 4 consecutive years (2011–2014) in the official Belgian antimicrobial resistance monitoring programme. Commensal Escherichia coli strains were isolated from faecal samples of four livestock categories (veal calves, young beef cattle, broiler chickens and slaughter pigs) and the trends of resistance profiles were analysed. The resistance prevalence remained high (>50%) during the study period for ampicillin in veal calves and chickens, for ciprofloxacin and nalidixic acid in chickens, for sulfamethoxazole in veal calves, chickens and pigs and for tetracycline in veal calves. Using logistic regression and Generalized Estimating Equation and after p value adjustment for multiple testing (Linear step-up method), statistically significant decreasing temporal trends were observed for several of the 11 tested antimicrobials in several livestock categories: in veal calves (10/11), in chickens (6/11) and in pigs (5/11). A significant increasing trend was observed for the prevalence of resistance to ciprofloxacin in chickens. Multi-resistance, considered as the resistance to at least three antimicrobials of different antibiotic classes, was observed in the four livestock categories but was significantly decreasing in veal calves, chickens and pigs. Overall, the prevalence of resistance and of multi-resistance was lowest in the beef cattle livestock category and highest in broiler chickens. These decreasing temporal trends of antimicrobial resistance might be due to a decrease of the total antimicrobial consumption for veterinary use in Belgium which was reported for the period between 2010 and 2013. The methodology and statistical tools developed in this study provide outputs which can detect shifts in resistance levels or resistance trends associated with particular antimicrobial classes and livestock categories. Such outputs can be used as objective evidence to evaluate the possible efficacy of measures taken by animal health authorities and stakeholders in the livestock sector to limit antimicrobial resistance occurrence.

Effect of different levels of calcium and phosphorus and their interaction on the performance of young broilers

A study was conducted to evaluate the interaction among 3 levels of Ca and 4 levels of nonphytate phosphorus (NPP) on broiler performance, bone ash, and whole-body fractional retention of Ca and P. Ross male broiler-chicks (n = 420) were sorted by BW at d 1 posthatch and assigned to 5 cages/diet with 7 birds/cage. Twelve diets were arranged in a 3 × 4 factorial of 3 levels Ca (at 0.5, 0.7, or 0.9%) and 4 levels NPP (at 0.25, 0.31, 0.38, or 0.45%) with a high dose of phytase (1,150 U/kg) in all diets. On d 14, chickens were euthanized and the right tibia was collected from 3 birds/replicate; the rest of the animals were used to measure whole-body Ca and P retention. An interaction was observed between the level of Ca and NPP on feed intake (FI), tibia weight, and bone-ash content (P < 0.05). Increasing the level of NPP from 0.25 to 0.38% increased FI (P < 0.05) on chickens fed the high-Ca diet (0.9%), but not with Ca at 0.5 or 0.7%. Broilers achieved their greatest weight gain (WG) and bone formation with 0.7% Ca and 0.38% NPP. Increasing the dietary Ca decreased its fractional retention from 74% with dietary Ca at 0.5 to 46% with Ca at 0.9%. The increase in the levels of dietary P steadily increased the fractional retention of Ca from 53 to 61%, and increased the whole-body Ca content (g/kg BW). It can be concluded that a dietary level of 0.38% NPP/kg in diets containing a high dose of phytase (1,150 U/kg) and 0.7% Ca are adequate to ensure broiler performance and bone ash of broilers from d 0 to d 14 posthatch.

RETRACTED ARTICLE: Role of aflatoxin toxicity on transmissibility and pathogenicity of H9N2 avian influenza virus in turkeys

We, the Editors and Publisher of the journal Avian Pathology, have retracted the following article: Sajid Umar, Muhammad Younus, Muti Ur Rehman, Asim Aslam, Muhammad Ali Abdullah Shah, Muhammad Tanveer Munir, Sajjad Hussain, Farooq Iqbal, Muhammad Fiaz & Sami Ullah, ‘Role of aflatoxin toxicity on transmissibility and pathogenicity of H9N2 avian influenza virus in turkeys’ (44:4, 2015) https://www.tandfonline.com/doi/full/10.1080/03079457.2015.1046813 The above article has been retracted as, subsequent to publication, significant duplication has been found in content with the following earlier published works: (Now withdrawn): Sajid Umar, Muhammad Tanveer Munir, Sabir Subhan, Tariq Azam, Qamarun Nisa, Muhammad Irfan Khan, Wajid Umar, Zaibur Rehman, Abdul Sattar Saqib, Muhammad Ali Shah. 2016. Protective and antiviral activities of Nigella sativa against avian influenza (H9N2) in turkeys. Journal of Saudi Society of Agricultural Sciences. Link: https://www.sciencedirect.com/science/article/pii/S1658077X16300340?via%3Dihub S. Umar, M.A.A. Shah, M.T. Munir, M. Yaqoob, M. Fiaz, S. Anjum, K. Kaboudi, M. Bouzouaia, M. Younus, Q. Nisa, M. Iqbal and W. Umar. 2016. Synergistic effects of thymoquinone and curcumin on immune response and anti-viral activity against avian influenza virus (H9N2) in turkeys. Poultry Science, 95(7), pp 1513-1520. Link: https://www.sciencedirect.com/science/article/pii/S0032579119318474?via%3Dihub Zahid Hussain, Mohammad Zargham Khan and Zahoor ul Hassan. 2008. Production of Aflatoxins from Aspergillus flavus and acute aflatoxins in young broiler chicks. Pakistan Journal of Agricultural Sciences, 45(1). We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

Contribution of intestinal- and cereal-derived phytase activity on phytate degradation in young broilers

There is little consensus as to the capability of poultry to utilize dietary phytate without supplemental phytase. Therefore, an experiment was conducted to examine the extent to which endogenous phytase of intestinal and cereal origin contributes to phytate degradation in birds aged 0 to 14 d posthatch. Ross 308 broilers (n = 720) were fed one of 4 experimental diets with differing dietary ingredient combinations and approximate total phytate levels of 10 g/kg, dietary phytase activity analyzed at 460 U/kg, dietary calcium (Ca) levels of 11 g/kg, and nonphytate-phosphorus (P) levels of 4 g/kg. Broiler performance, gizzard, duodenum, jejunum and ileum pH, Ca and P digestibility and solubility, amount of dietary phytate hydrolyzed in the gizzard, jejunum, and ileal digesta phytase activity were analyzed at d 4, 6, 8, 10, 12, and 14 posthatch. Intestinal endogenous phytase activity increased significantly (P < 0.001) between d 4 and 6, resulting in increased phytate hydrolysis in the gizzard (P = 0.003), jejunum (P < 0.001), and ileum (P < 0.001). Phytase activity and phytate hydrolysis continued to increase with age, with a greater phytase activity and associated increase in phytate hydrolysis and mineral utilization between d 10 and 12. Gizzard and jejunum Ca and P solubility and ileal Ca and P digestibility increased significantly (P < 0.001), and gastrointestinal pH decreased significantly (P < 0.001) between d 4 and 6. By d 14, phytase activity recovered in the ileum was approximately 45 U/kg. There were strong correlations between phytase activity measured in the ileum and phytate hydrolyzed in the gizzard (r = 0.905, P < 0.001), jejunum (r = 0.901, P = 0.023), and ileum (r = 0.938, P = 0.042). This study shows intestinal- and dietary-derived endogenous phytase activity is responsible for phytate-P hydrolysis in broilers.

How Effective are Federal Food Safety Regulations? The Case of Eggs and Salmonella Enteritidis

In 2009 the Food and Drug Administration (FDA) estimated that its shell egg rule would reduce illness from Salmonella Enteritidis (SE) by about 79,000 cases annually (37%), with a range from about 30,000 to 191,000 cases avoided. I assess the effectiveness of this rule, which requires farmers who sell eggs to adopt SE control measures, by comparing illness from SE with illness from other Salmonella serotypes, using a differences-in-differences approach. The data reject the hypothesis that the rule reduced illnesses by FDA’s best 2009 estimate, but do not reject a hypothesis of no effect. The percentage of young broilers that test positive for SE has a modest effect on the incidence of human cases of salmonellosis caused by SE. Recent literature offers two other reasons to adjust FDA’s prospective 2009 calculations. One adjustment would follow the Centers for Disease Control’s use of a lower multiplier to infer the total number of (unobserved) cases of illness from those confirmed by positive lab tests. A second adjustment would lower the average cost of Salmonella cases, by recognizing lower risk of severe sequelae. These adjustments and the new retrospective assessment of the effectiveness of the rule together suggest that the benefits of FDA’s egg rule may be a small fraction of the prospective estimate of benefits, and less than the prospective estimate of costs. I conclude with some policy recommendations to make food safety regulations more effective.

Products to alleviate the effects of necrotic enteritis and aflatoxin on growth performance, lesion scores, and mortality in young broilers

This study investigated the effects of necrotic enteritis challenge or a necrotic enteritis challenge with an additional challenge from dietary aflatoxin B1 compared to broilers that were unchallenged. Also tested were products designed to help alleviate those effects. Lesion scores were higher in broilers challenged to induce necrotic enteritis, but this did not increase with added aflatoxin. The presence of dietary aflatoxin during a necrotic enteritis challenge significantly increased the negative effects of the necrotic enteritis challenge. During the necrotic enteritis challenge virginiamycin, Calibrin-Z, or a blend of Calibrin-Z, an organic acid, and yucca, helped to decrease the effects of the challenge. When birds are challenged with necrotic enteritis and dietary aflatoxin is present, Calibrin-Z had an advantage over all other tested products.

Effects of feed grade L-methionine on intestinal redox status, intestinal development, and growth performance of young chickens compared with conventional DL-methionine.

This study was conducted to test the effects of supplemental L-Met on redox status, gut development, and growth performance of young broiler chickens compared with DL-Met. A total of 888 (half male and half female) 1-d-old Ross 308 chickens were weighed and randomly allotted to 7 treatments in a randomized complete block design for 21 d, including a basal diet (BD), the BD + 0.095% L-Met or DL-Met, the BD + 0.190% L-Met or DL-Met, and the BD + 0.285% L-Met or DL-Met (representing 60, 70, 80, and 90% of the Met + Cys requirement). Feed disappearance and BW were recorded every 7 d. Liver and duodenum samples were collected on d 0, 7, and 21 to measure redox status and intestine morphology. On d 7, chicks fed a diet supplemented with either 0.285% L-Met or 0.285% DL-Met had increased (P < 0.05) concentrations of glutathione (GSH) and reduced (P < 0.05) protein carbonyl (PC) and malonedialdehyde contents in duodenum mucosa compared with chicks fed the BD. Chicks fed a diet supplemented with 0.285% L-Met had greater (P < 0.05) villus width compared with chicks fed a diet supplemented with 0.285% DL-Met. Chicks fed a diet supplemented with 0.285% L-Met had lower (P < 0.05) crypt depth and greater (P < 0.05) villus height:crypt depth ratio compared with chicks fed a diet supplemented with 0.285% DL-Met or the BD. On d 21, chicks fed a diet supplemented with 0.285% L-Met had increased (P < 0.01) concentrations of GSH and total antioxidant capacity (TAC) but reduced (P < 0.05) PC content in duodenum mucosa compared with chicks fed a diet supplemented with 0.285% DL-Met and the BD. Chicks fed a diet supplemented with 0.285% L-Met had greater (P < 0.05) villus height compared with chicks fed the BD. During the entire 21-d supplementation of either L-Met or DL-Met, ADG and G:F were enhanced (P < 0.01) compared with chicks fed the BD. Chicks fed diets supplemented with L-Met had greater (P < 0.05) ADG and G:F than chicks fed diets supplemented with DL-Met. The relative bioavailability of L-Met to DL-Met for ADG and G:F was 138.2 and 140.7%, respectively. Overall, supplementation of either L-Met or DL-Met has beneficial effects on villus development in association with increased GSH production and levels of TAC and reduced protein oxidation in duodenum. Supplementation of L-Met served a better function on redox status and development of the gut of chicks compared with DL-Met. Chicks fed diets with L-Met had better growth response than chicks fed diets with DL-Met.

Influence of separate feeding of calcium on nutrient digestibility, energy utilisation and performance of young broilers fed pelleted wheat-based diets

Six broiler starter diets, based on wheat and soybean meal, were formulated to contain 1.1 2.0, 4.0, 6.0, 8.0 and 10.0g calcium (Ca)/kg. All diets were equivalent in respect of total and non-phytate phosphorus contents (5.4 and 3.0g/kg, respectively). The influence of dietary treatments on the growth performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat and phosphorus (P), Ca retention and apparent metabolisable energy (AME) in broiler starters was evaluated. A total of 288, one-day-old male broilers (Ross 308) were allocated to 36 cages (8birds/cage), and cages were randomly assigned to 6 dietary treatments. Birds were also provided with a source of Ca in a separate feed trough. Birds fed the diet with 1.1g Ca/kg gained more (P<0.05) weight and tended (P=0.08) to have higher feed intake than those fed the diets with 8.0 and 10.0g Ca/kg. Increasing dietary Ca concentrations from 1.1 to 8.0g/kg increased (P<0.05) feed per unit gain, but diets with 1.1 and 10.0g/kg Ca resulted in similar (P>0.05) feed per unit gain. During d 8 to 14, d 15 to 21, and over the entire trial period of 21 d, birds fed Ca-deficient (6.0g Ca/kg and less) diets consumed more (P<0.001) of the separate Ca source. During the third week and over the 21 d trial period, total Ca intake (Ca from feed plus Ca from separate source) of birds fed Ca-insufficient diets was higher (P<0.05) than those fed diets with higher dietary Ca concentrations. Diets with 1.1g Ca/kg resulted in the highest (P<0.05) CAID of P. There was no effect (P>0.05) of dietary Ca on the retention of Ca and ash, AME and toe ash. The present data suggest that feeding broilers low Ca diets with access to a separate Ca source, is advantageous in terms of broiler performance, while maintaining bone mineralisation. The data also demonstrate that the provision of separate Ca source may hold promise for reducing the dietary P contents.

Consumption of Oxidized Soybean Oil Increased Intestinal Oxidative Stress and Affected Intestinal Immune Variables in Yellow-feathered Broilers.

This study investigated the effect of oxidized soybean oil in the diet of young chickens on growth performance and intestinal oxidative stress, and indices of intestinal immune function. Corn-soybean-based diets containing 2% mixtures of fresh and oxidized soybean oil provided 6 levels (0.15, 1.01, 3.14, 4.95, 7.05, and 8.97 meqO2/kg) of peroxide value (POV) in the diets. Each dietary treatment, fed for 22 d, had 6 replicates, each containing 30 birds (n = 1,080). Increasing POV levels reduced average daily feed intake (ADFI) of the broilers during d 1 to 10, body weight and average daily gain at d 22 but did not affect overall ADFI. Concentrations of malondialdehyde (MDA) increased in plasma and jejunum as POV increased but total antioxidative capacity (T-AOC) declined in plasma and jejunum. Catalase (CAT) activity declined in plasma and jejunum as did plasma glutathione S-transferase (GST). Effects were apparent at POV exceeding 3.14 meqO2/kg for early ADFI and MDA in jejunum, and POV exceeding 1.01 meqO2/kg for CAT in plasma and jejunum, GST in plasma and T-AOC in jejunum. Relative jejunal abundance of nuclear factor kappa B (NF-κB) P50 and NF-κB P65 increased as dietary POV increased. Increasing POV levels reduced the jejunal concentrations of secretory immunoglobulin A and cluster of differentiation (CD) 4 and CD8 molecules with differences from controls apparent at dietary POV of 3.14 to 4.95 meqO2/kg. These findings indicated that growth performance, feed intake, and the local immune system of the small intestine were compromised by oxidative stress when young broilers were fed moderately oxidized soybean oil.

Role of the serotonergic axis in the reproductive failure associated with aging broiler breeder roosters

Reproductive failure associated with aging is a well-known phenomenon. However, the mechanism by which this failure occurs in broiler breeder roosters is still unclear. A previous study conducted in our laboratory, comparing young and aging broiler breeder roosters, demonstrated an elevation in hypothalamic vasoactive intestinal peptide (VIP) and pituitary prolactin (PRL) gene expression accompanied by a deterioration of gonadal axis function. This resulted in a decrease in semen-quality variables as roosters aged. The objective of this study was to examine the involvement of the serotonergic axis in the age-associated reproductive failure in broiler breeder roosters. Cobb roosters aged 64 wk were divided into 3 groups (n = 20 each): parachlorophenylalanine (PCPA) administration, active immunization against chicken VIP, and controls. At 69 wk of age, each group was divided into 2 equal subgroups: 1 received ovine PRL and the other served as controls. Weekly semen volume, concentration and motility, and plasma testosterone, estradiol, and PRL concentrations were examined. At the end of the experiment, roosters were euthanized, testes were weighed, and hypothalamus and pituitary were removed to assay the expression of genes encoding hypothalamic GnRH-I, pituitary FSH, pituitary LH, hypothalamic VIP, and pituitary PRL. Both PCPA administration and active immunization against chicken VIP significantly increased testis weight, semen volume, sperm concentration, ejaculation grade, plasma testosterone level, and GnRH-I, FSH and LH gene expression compared with controls (P ≤ 0.05). In addition, a decrease in plasma estradiol and PRL concentrations and VIP and PRL gene expression was observed in PCPA- and VIP-immunized birds compared with controls (P ≤ 0.05). Administration of PRL in all groups decreased gonadal axis function and semen-quality variables (P ≤ 0.05). Collectively, these results suggest that the increasing expression levels of the serotonergic axis in aging broiler breeder roosters inhibit proper gonadal function and reproductive performance. This article establishes for the first time the inhibitory role of serotonin on reproduction in aging roosters.

Isolation, identification, and pathogenicity of O142 avian pathogenic Escherichia coli causing black proventriculus and septicemia in broiler breeders

Avian colibacillosis, characterized by black proventriculus and caused by avian pathogenic Escherichia coli (APEC) with an uncommon O142 serogroup, was diagnosed in young broiler breeders. Colonization and persistence assays performed in 7-day-old broilers showed that the bacterial load of the APEC 4d/9-1 O142 proventricular isolate in the lung was about 10-fold higher than that of the APEC 4d/9-1 O142 heart blood isolate (P<0.01), and about 100-fold higher in the heart blood, livers, spleens, kidneys, and proventriculi of inoculated broilers (P<0.001). When 32 common virulence genes of APEC were tested, the two isolates had nearly identical profiles, except that only the APEC 4d/9-1 O142 proventricular isolate carried the feoB gene. Furthermore, 100% mortality was observed in both 1-day-old Arbor Acres (AA) broilers and 1-day-old specific-pathogen-free (SPF) chickens inoculated with 106 colony-forming units of the APEC 4d/9-1 O142 proventricular isolate. However, black proventriculus was only observed in the dead AA broilers, consistent with the clinical occurrence of the disease. This implies that the black proventriculi seen in the dead birds, caused by the APEC 4d/9-1 O142 proventricular isolate, was breed-specific. Both the APEC 4d/9-1 O142 proventricular and heart blood isolates belong to phylogroup B2. However, the former was assigned to ST131 and the latter to ST2704 with multilocus sequence typing, demonstrating the genetic heterogeneity of these two bacterial isolates, although they were derived from the same dead broiler. These results suggest that the O142 APEC isolate was the main pathogenic agent for black proventriculi in 7-day-old broiler breeders.

Effect of biological corn stover replacing partial corn meal on production performance, nutrient metabolic rates and carcass characteristics of broilers

In order to increase nutritive values of corn stover, steam explosion and microbial fermentation were used together to make biological corn stover (BCS) for replacing partial corn meal in broiler diet. The experiments were assigned to 5 groups. Group 1 was the control, group 2-4 was added with 4%, 8% and 12% BCS for replacing the same amount of corn meal, group 5 was the same as group 3 except for its ME level adjusted. The results indicated that inclusion of BCS in young broiler diets decreased average daily gain (ADG) and increased feed conversion rate (FCR) significantly (P0.05). It could be concluded that 4-8% BCS in diets as an alternative grain source was optimal for elder broiler production.