Cellular and humoral immunity of broilers subjected to posthatch fasting and a prestarter diet containing conjugated linoleic acid

This study aimed to evaluate the immunity of chickens up to 35 d subjected to posthatch fasting and supplementation with conjugated linoleic acid (CLA). A total of 320 chicks were housed in a completely randomized design with a 2 × 2 factorial arrangement (0 or 12 h of fasting × 0.000 or 0.025% CLA in a prestarter diet), totaling 4 treatments (No-F-12 h; F-12 h; No-CLA; CLA) with 8 replicates of 10 birds each. The relative weights (% body weight) of the spleen and bursa were determined 12 h posthatch (Post-12 h) and then weekly. Immunoglobulin Y (IgY) titers against Newcastle disease virus (NDV) were measured by ELISA in the yolk sac contents Post-12 h and in the serum weekly. Hypersensitivity to phytohemagglutinin (PHA) inoculation was evaluated by toe-web swelling response on d 13 and 34, 4 times a day (after 3 h, 6 h, 12 h, and 24 h inoculation, respectively, PHA-3 h, PHA-6 h, PHA-12 h, and PHA-24 h). The data were subjected to analysis of variance (P < 0.05). F-12h reduced the Post-12 h relative weight of the spleen, and CLA reduced the relative weight of the bursa at this stage and at 28 d. At 13 d, F-12 h reduced PHA-3 h, whereas PHA-12 h was increased by CLA. At 34 d, CLA reduced PHA-3 h. A greater reaction was observed in the No-F-12 h-CLA chicks, for the PHA-24 h. In the Post-12 h evaluation, F-12h reduced, whereas CLA increased NDV-specific IgY titers in the yolk sac. No-F-12 h-No-CLA chicks had the lowest serum titers. At 21 d, F-12 h-CLA chicks exhibited the highest serum titers. Titers were higher in the F-12 h-No-CLA chicks, when compared to other treatments. At 28 d, fasting reduced the titers. In conclusion, F-12 h and CLA accelerated the transfer of immunoglobulins from the yolk sac to the serum. F-12 h impairs cellular immunity, whereas CLA favors it.

Research Note: Effects of feeding corn naturally contaminated with aflatoxin B1, deoxynivalenol, and zearalenone on reproductive performance of broiler breeders and growth performance of their progeny chicks

To evaluate the toxic effects of mycotoxin-contaminated corn (MC) on the breeders and their progeny chicks, a total of 480 fifty-wk-old Cobb broiler breeder hens were fed the following dies: 1) a corn-soybean meal diet (Control; containing 70.35% corn), 2) MC substituting for 50% of corn in Control (LM), 3) LM diet plus 2 g/kg 1 mycotoxin sequestrant, Toxy-Nil Plus (TNP) (LMT2.0), 4) MC substituting for 100% of corn in Control (HM), 5) HM diet plus 2 g/kg TN (HMT2.0), and 6) HM diet plus 2.5 g/kg TNP (HMT2.5). The MC contained 69.25 μg aflatoxin B1 (AFB1)/kg, 4,875 μg deoxynivalenol (DON)/kg, and 2,262 μg zearalenone (ZEN)/kg. At wk 4 after MC inclusion, all eggs laid were used for hatch, and all progeny chicks were fed the same mycotoxin-untreated diet for 14 d. Dietary MC inclusion decreased the hatchability of set eggs and increased embryo mortality during d 18 to 21.5. The TNP addition increased these aforementioned indices in MC-included diets. Maternal HM treatment decreased the BW of progeny chicks at age of 14 d and BWG of progeny chicks during d 1 to 14, whereas maternal LM treatment did not affect these indices. In parallel, maternal HM treatment decreased the concentrations of serum IgA, IgG, and lysozyme in the progeny chicks on d 14, but maternal LM treatment did not affect these indices. Overall, maternal dietary TNP treatments increased the growth of progeny chicks and had a trend to increase the concentrations of serum IgA and IgG on d 14 compared to maternal MC treatments. It was concluded that the feeding of relative high ratio of corn contaminated with low level of AFB1, DON, and ZEN negatively affected the reproductive performance of breeders and the growth performance of their progeny chicks, and TNP addition alleviated these toxic effects.

Addition of a protected complex of biofactors and antioxidants to breeder hen diets confers transgenerational protection against Salmonella enterica serovar Enteritidis in progeny chicks

Addition of vitamins and antioxidants has been long associated with increased immunity and are commonly used in the poultry industry; however, less is known regarding their use in broiler breeder hens. The objective of this study was to determine if feeding a complex of protected biofactors and antioxidants composed of vitamins and fermentation extracts to broiler breeder hens conferred resistance against Salmonella enterica serovar Enteritidis (S. Enteritidis) in the progeny chicks. Three-day-old chicks from control- and supplement-fed hens were challenged with S. Enteritidis and necropsied 4- and 11-days postchallenge (dpc) to determine if there were differences in invasion and colonization. Serum and jejunum were evaluated for various cytokine and chemokine production. Fewer (P = 0.002) chicks from supplement-fed hens had detectable S. Enteritidis in the ceca (32.6%) compared to chicks from control-fed hens (64%). By 11 dpc, significantly (P < 0.001) fewer chicks from supplement-fed hens were positive for S. Enteritidis (liver [36%]; ceca [16%]) compared to chicks from the control hens (liver [76%]; ceca [76%]). The recoverable S. Enteritidis in the cecal content was also lower (P = 0.01) at 11 dpc. In additional to the differences in invasion and colonization, cytokine and chemokine production were distinct between the 2 groups of chicks. Chicks from supplement-fed hens had increased production of IL-16, IL-6, MIP-3α, and RANTES in the jejunum while IL-16 and MIP-1β were higher in the serum of chicks from the control-fed hens. By 11 dpc, production of IFN-γ was decreased in the jejunum of chicks from supplement-fed hens. Collectively, these data demonstrate adding a protected complex of biofactors and antioxidants to the diet of broiler breeder hens offers a measure of transgenerational protection to the progeny against S. Enteritidis infection and reduces colonization that is mediated, in part, by a robust and distinct cytokine and chemokine response locally at the intestine and systemically in the blood.

Short communication: Effects of breeder age and pre-placement feed on IgY concentration in egg yolk and chick serum

Breeder age and pre-placement feed are factors that can affect broiler performance during grow out. This study evaluated the effects of breeder age (29 and 55 weeks old) on IgY transference to egg yolk in addition to the effects of breeder age (29 and 55 weeks old) and pre-placement feed (with or without), in a factorial arrangement, on IgY concentration in chick serum. Forty-eight eggs were collected from a breeder flock and considered the experimental units. Eighteen chicks from each breeder age were randomly selected to determine IgY at pulling. After 48 h of placement, old breeders had greater egg weight and yolk weight (p ≤ 0.05) than the young ones. Breeder age (p > 0.05) had no effect on IgY concentration of egg yolk. Breeder age (p > 0.05) had no effect on IgY concentration of chick serum at pulling. There was no interaction (p > 0.05) between breeder age and pre-placement feed for IgY concentration of chick serum at housing. There was also no effect of breeder age or pre-placement feed during placement time (48 h) on IgY concentration of chick serum at housing (p > 0.05). In conclusion, 48 h of fasting had no effect on IgY concentration in chick serum despite breeder age. It appears that the immunoglobulins from the residual yolk sac are not used as a protein source during the period between hatching and housing.

HISTOMORFOMETRIA DE ORGÃOS LINFOIDES E DESENVOLVIMENTO INTESTINAL DE PINTOS DE CORTE ORIGINADOS DE MATRIZES COM DIFERENTES IDADES E SUBMETIDOS AO ESTRESSE POR CALOR NA INCUBAÇÃO

Resumo: Objetivou-se avaliar o efeito da idade da matriz e da variação da temperatura de incubação sobre a qualidade do pinto neonato. O delineamento foi inteiramente casualizado em esquema fatorial 3x2 (três idades x duas temperaturas de incubação). Foram incubados 720 ovos, provenientes de matrizes com diferentes idades (30, 42 ou 64 semanas). A temperatura da máquina de incubar para os grupos controle foi mantida constante (37,5 ºC) e para os tratamentos com estresse por calor foi aplicada uma temperatura de 39,0 ºC por 6h durante o período de 10 a 18 dias de incubação. Cinco pintos por tratamento foram sacrificados para coletas de órgãos e realizada a histomorfometria intestinal, de baço e bursa. Os dados foram submetidos a análise de variância e foi utilizado o teste de Tukey (5%). A área dos folículos da bursa foi maior nos pintos oriundos de matrizes mais velhas quando os ovos foram incubados em temperatura ideal. A temperatura de 39,0 ºC estimulou o desenvolvimento intestinal. A variação na temperatura de incubação prejudicou a qualidade de pintos, sobretudo para pintos originados de matrizes jovens. Pintos oriundos de matrizes velhas apresentaram melhor resposta imune e desenvolvimento intestinal, independentemente da variação da temperatura de incubação.

Practical aspects in the use of passive immunization as an alternative to attenuated viral vaccines

Passive immunization as a method to protect birds has been tested for many years and shown to be effective. Its advantages over active vaccination include no use of partially virulent viruses, overcoming the gap in the level of protection at young age due to interference of maternal antibodies to raise self-immune response following active vaccination and the possible immunosuppressive effect of attenuated vaccine viruses. However, a major obstacle to its implementation is its relatively high cost which is dependent, among other things, mainly on two factors: the efficacy of antibody production, and the use of specific pathogen-free (SPF) birds for antibody production to avoid the possible transfer of pathogens from commercial layers. In this study we show efficient production of immunoglobulin Y (IgY) against four different pathogens simultaneously in the same egg, and treatment of the extracted IgY with formalin to negate the need for SPF birds. Formalin, a common registered sterilization compound in vaccine production, was shown not to interfere with the Fab specific antigen binding or Fc-complement activation of the antibody. Following injection of 1-day-old broilers with antibodies against infectious bursal disease virus, protective antibody levels were acquired for the entire period of sensitivity to this pathogen (35 days). Passive vaccination with formalin-sterilized IgY against multiple antigens extracted from one commercial egg may be a cost-effective and advantageous complementary or alternative to attenuated vaccines in poultry.

Effect of broiler breeder feeding programme and feeder space change at photostimulation using maize- or wheat-based diets on broiler progeny growth performance and leg health

1. The aim of this study was to evaluate the effects of diet type, maternal feeding programme at 29 weeks of age and breeder feeder space change at photostimulation on broiler progeny performance and leg health at 6 weeks of age. 2. Fast-feathering Cobb 500 broiler breeders were fed on either maize- or wheat-based diets that had been formulated to have similar nutrient composition during growing and layer phases. Two feeding programmes, fast or flow, were used from 14 to 29 weeks of age. At 22 weeks, 69 females from each pen were placed in a layer house where feeder space was either similar to that in rearing (6.3 to 6.5 cm/female) or was increased from 6.3 to 8.4 cm/female. Eggs produced at 32 and 44 weeks of age were collected and incubated for two broiler experiments. A total of 16 male and 16 female one-d-old chicks were placed in floor pens in two experiments, respectively, with 6 and 4 replicate pens. Broiler gait scores and leg problem prevalence were evaluated at 6 weeks of age. 3. Data were analysed as a 2 × 2 × 2 factorial design with diet type, feeding programme and feeder space change as main factors. 4. The wheat diet increased the probability of observing crooked toes in broiler progeny compared to the use of maize, but only when breeders were fed according to the fast feeding programme and given similar feeder space as during rearing. 5. Breeders given more feeder space in the laying period produced progeny with more locomotion problems compared with those provided similar feeder space, but only when maize was used and the slow feeding programme was applied to the breeders. 6. The maternal feeding programme interacted with other factors to influence progeny leg health, but it did not solely influence walking ability or leg problems of progeny. 7. In conclusion, an increased probability of observing walking impairment of broiler progeny was detected when breeders were given greater feeder space at photostimulation rather than no change and fed according to the slow feeding programme using maize diets in breeders and progeny.

Overcoming the susceptibility gap between maternal antibody disappearance and auto-antibody production

In the first 10-14 days of a chick's life, protection is conferred by maternal antibodies. Further broiler protection is achieved by active vaccination. However, the high level of maternal antibodies interferes with the induction of an effective immune response by vaccination at a young age. As a result, there is a gap between the reduction in protective maternal antibodies and elevation of self-produced antibodies following active vaccination. The major aim of this study was to test an approach consisting of passive and active vaccination to overcome this gap and to provide continuous resistance to infectious viral diseases during the broiler's growth period. Newcastle disease virus (NDV), which is one of the world's most prevalent infectious diseases of poultry, was tested as a model. Following subcutaneous injection of 18 hemagglutination-inhibiting (HI) units of anti-NDV immunoglobulin Y per 1-day-old chick, protective log2 antibody titers above 4 could be detected to at least 17 days of age. The combination of passive immunization on day 1 of age with attenuated live vaccination on day 10 led to high protective titers throughout the entire growth period, up to 41 days of age. Moreover, the HI titers in the group of birds immunized with the combined vaccination were significantly more homogeneous than those in the group vaccinated only with live virus. Thus, full protection against NDV of all broilers in flock during their entire growth period was achieved by a vaccination regime that combines passive immunization and live vaccination.