Comparison of necrotic enteritis effects on growth performance and intestinal health in two different meat-type chicken strains Athens Canadian Random Bred and Cobb 500

Chickens have undergone genetic improvements in the past few decades to maximize growth efficiency. However, necrotic enteritis (NE), an enteric disease primarily caused by C. perfringens, remains a significant problem in poultry production. A study investigated the differences in intestinal health between the nonselected meat-type chicken Athens Canadian Random Bred (ACRB) and the modern meat-type Cobb 500 broilers (Cobb) when challenged with experimental NE. The study utilized a 2 × 3 factorial arrangement, consisting of two main effects of chicken strain and NE challenge model (nonchallenged control, NC; NE challenge with 2,500/12,500 Eimeria maxima oocysts + 1 × 109C. perfringens, NE2.5/NE12.5). A total of 432 fourteen-day-old male ACRB and Cobb were used until 22 d (8 d postinoculation with E. maxima on d 14, dpi), and the chickens were euthanized on 6 and 8 dpi for the analysis. All data were statistically analyzed using a two-way ANOVA, and Student's t-test or Tukey's HSD test was applied when P < 0.05. The NE12.5 group showed significant decreases in growth performance and relative growth performance from d 14 to 20, regardless of chicken strain (P < 0.01). The ACRB group exhibited significant decreases in relative body weight and relative body weight gain compared to the Cobb group from d 14 to 22 (P < 0.01). On 6 and 8 dpi, both NE challenge groups showed significant decreases in intestinal villus height to crypt depth ratio, jejunal goblet cell count, and jejunal MUC2 and LEAP2 expression (P < 0.01). Additionally, the NE12.5 group had significantly higher intestinal NE lesion score, intestinal permeability, fecal E. maxima oocyst count, intestinal C. perfringens count, and jejunal IFNγ and CCL4 expression compared to the NC group (P < 0.05). In conclusion, NE negatively impacts growth performance and intestinal health in broilers, parameters regardless of the strain.

The ability to resist Newcastle disease through inherited immunity in different strains of broilers in Nineveh governorate

Background

Newcastle disease (ND) is a viral disease that affects numerous bird species and is still present in many places, including Iraq.

Aim

The purpose of this study was to compare maternal derived antibodies against against ND vaccination in 1-day-old imported Cobb 500 and Ross 308 chicks.

Methods

From April to October 2020, four locations in Mosul governorate were chosen to compute the maternal derived antibodies from 1-day-old broiler chicks. Seven hundred and seven blood samples (451) from imported 28 Ross 308 flocks and 256 from 17 Cobb 500 flocks were obtained and tested for antibody levels using an indirect enzyme-linked immunosorbent assay assay (BioChek commercial kit, UK).

Results

The Cobb 500 broiler chicks outperformed the Ross 308 broiler chicks in that all of the Cobb 500 broiler chicks had maternal antibody titers (100% positivity) versus 97.78% of the Ross 308 chicks, had a mean Maternal antibody titer of 9,871.47 versus 8,647.76, and had a mean CV percentage of 12.41% versus 15.18%, respectively. The mean vaccination index of Cobb 500 broiler chicks was 966.59 versus 821.60 for Ross 308 broiler chicks.

Conclusion

Although both broiler types produced chicks with high and uniform maternal antibody titers, Cobb 500 produced chicks with higher protective titers than Ross 308.

Evolvement of taste sensitivity and taste buds in chickens during selective breeding

Chickens have been reported to have a low taste bud count and thus low taste acuity. However, more recent studies indicate that the earlier reported count of chicken taste buds may have been significantly underestimated. To answer the question of whether the taste sensing system in broiler chickens evolved during the breeding selection over the past decades, we compared the taste sensitivity to bitter and taste buds between a meat-type control strain – the 1955 Athens Canadian Random Bred (ACRB), and a modern high-yielding broiler strain – the 2012 Cobb 500. The behavioral tests showed that the ACRB did not avoid bitter taste solutions of quinine hydrochloride (QHCl) at the examined concentrations (0.5, 1, 2, and 4 mM) (P > 0.05), while the Cobb 500 significantly avoided both the 2 mM and 4 mM QHCl solutions (P < 0.01). The labeling of chicken taste buds using the molecular marker Vimentin revealed that Cobb 500 chickens had a slightly higher number (P < 0.1), but lower density of taste bud clusters in the palate (P < 0.01) and the base of the oral cavity (P < 0.05) compared to the ACRB. We also found that a single amino acid change occurred in the bitter taste receptor T2R7. However, the functional analyses using HEK293T cells transiently expressing T2R7 revealed that the functions of T2R7 were comparable between the two strains. Taken together, our results demonstrated that taste sensitivities could be affected by the selection of the broiler chickens. The modern high-yielding broilers, which have massive feed intake and appetite, had a higher sensitivity to bitter taste stimuli than the meat-type chicken strain which was established decades ago. This evolvement of taste sensitivities may be associated with the alterations of an upper level of taste system, rather than the peripheral taste system, including distribution of taste buds and functions of taste receptors.

Black proventriculus in Cobb 500 broiler breeders

The black proventriculus is a necropsy finding sign observed during post-mortem examinations of dead young chicks up to 10 days of age and due to variation in color of the affected proventriculus organ, it may be ignored in some cases, in particular when the disease occurs simultaneously with other well-recognized infections of two weeks old chicks. In late January 2018, several live and dead chicks with a history of an unusual increase in mortality showing no clinical signs but sudden dead were referred to the poultry clinic of Faculty of Veterinary Medicine, Urmia University, Urmia, Iran. General routine postmortem examination revealed color changes (light green to dark green color) in the wall of proventriculus together with some degrees of congestion in the lungs and liver of the dead chicks. Microbiology tests revealed that the causative agent was Escherichia coli strain O142 and histopathological examination indicated that the color changing of the organ was due to necrosis of glandular epithelium with locally extensive or diffuse hypercellularity by lymphocytes and macrophages with hemorrhages. In conclusion, black proventriculus due to E. coli strain O142 was responsible for the sudden death of young chicks and based on antibiogram, selective antibiotics should be used for the treatment of the affected flocks.

The optimum valine: lysine ratios on performance and carcass traits of male broilers based on different regression approaches

Three different regression approaches were applied to determine the optimal digestible (d.) and analyzed Val:Lys ratios for broiler performance and carcass yield. One-day-old male Cobb 500 broilers (n = 960) were assigned to 1 of 8 diets, with 6 pens/diet and 20 birds/pen, for 42 days. The negative control consisted of the basal diet with a d.Val:d.Lys ratio of 0.63 and with 93% of the required d.Lys. The positive control consisted of the basal diet with a d.Val:d.Lys of 0.80, with no reduction in d.Lys content. The other (test) diets contained a range of d.Val:d.Lys ratios, all with 93% of the required d.Lys. Data on feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were submitted to regression analysis, applying quadratic polynomial (QP), exponential asymptotic (EA), and linear response plateau (LRP) models. Since Val did not affect carcass or breast meat yield, no regression was performed. Digestible and analyzed Val:Lys ratios were similar based on the regression models. The intercept between the QP and LRP models was used to determine the optimum Val:Lys ratio. Overall, the ideal d.Val:d.Lys ratio will vary according to the main goal of poultry production, i.e., BWG or FCR. For BWG, the ideal ratio was found to be 0.78 (0 to 12 d), 0.73 (0 to 28 d), and 0.76 (0 to 35 or 0 to 42 d). For FCR, the optimum d.Val:d.Lys was found to be 0.80 (0 to 12 d), 0.75 (0 to 28 d), and 0.78 (0 to 35 or 0 to 42 d). The optimum analyzed Val:Lys ratio was slightly higher. For instance, for BWG the optimum ratio was 0.80 (0 to 12 d), 0.76 (0 to 28 d), and 0.79 (0 to 35 or 0 to 42 d). For FCR, the optimum Val:Lys was 0.81 (0 to 12 d), 0.79 (0 to 28 d), and 0.81 (0 to 35 or 0 to 42 d). Valine did not affect carcass or breast meat yield.

Comparative effects of inorganic and three forms of organic trace minerals on growth performance, carcass traits, immunity, and profitability of broilers

Objective:

The experiment was conducted to investigate the comparative effects of inorganic trace minerals (ITM) and three forms of organic trace minerals (OTM) (propionate, metho-chelated, and proteinate) on growth performance, edible meat yield, immunity, and profitability of commercial broilers.

Materials and methods:

A corn-soya based mash diet comprising four treatments each of 10 replicates were fed to 720 day-old Cobb 500 broiler chicks for 35 days (starter diet 0–21 days and grower diet 22–35 days). The diets for comparison were as follows: diet 1: control diet with ITM premix at 1 kg/ton of feed (T₁); diet 2: control diet supplemented with propionate trace minerals at 600 gm/ton (T₂); diet 3: control diet supplemented with metho-chelated trace minerals at 500 gm/ton by reducing 225 gm methionine/ton of feed (T₃); and diet 4: control diet supplemented with proteinate trace minerals at 500 gm/ton of feed (T₄). Growth performance, carcass yield, and antibody titer (AT) data were recorded. Data were analyzed and interpreted using SAS Computer Package Program version 9.1.

Results:

Feeding propionate and proteinate OTM showed similar performance. Birds fed these two types (propionate and proteinate) or OTM had better performance in comparison with those receiving ITM and metho-chelated one. Proteinate group produced more wing meat and propionate group showed higher breast and drumstick meat yield as compared with those received the metho-chelated trace mineral and ITM. The birds belonging to OTM groups showed significantly higher AT level against infectious bursal disease. Proteinate minerals groups showed higher profitability followed by propionate fed broilers.

Conclusion:

Two forms of OTM, propionate and proteinate improved performance of commercial broilers over those of ITM and metho-chelated one.