Poultry Science Journal
Volume:11 Issue: 1, Winter-Spring 2023

Avian Metapneumovirus infection first emerged in South African turkeys, followed by respiratory problems in chickens with a swollen head syndrome. The etiological agent is a Metapneumovirus in the Pneumoviridae family and the first pneumovirus identified in avian species. This virus causes respiratory and reproductive affections that are worsened in the presence of other pathogens. The present review summarized the current knowledge about the virus’s properties and spread, its different subtypes, and the immunological and pathological mechanisms, especially in the broilers. The diagnostic methods are based on serology and essentially ELISA to show and titer antibodies following infection in naïve birds. Molecular tools such as PCR aim to detect and subtype avian Metapneumovirus genetic material. Besides biosecurity, prevention relies mostly on good management and vaccination.

Antibiotic resistance is a growing concern all over the world. The current study sought to identify antimicrobial resistance (AMR) patterns and antibiotic-resistant genes in Escherichia coli (E. coli) isolated from seemingly healthy ducks and neighboring tap water sources at three separate live bird markets (LBMs) in Chattogram, Bangladesh. A total of ninety cloacal swab samples of Khaki Campbell ducks and fifteen water samples from nearby tap water sources were collected from three LBMs. Several cultural and molecular tests were conducted to determine  E. coli contamination. The disk diffusion technique was used to evaluate the antibiotic sensitivity of E. coli isolates to 12 different antibiotics. For each isolate, a Multiple Antibiotic Resistance (MAR) index was calculated. The resistance genes were detected using a polymerase chain reaction (PCR) assay. The overall prevalence of E. coli in feces and tap water samples was 64.4% (58/90, 95% CI 54.1-73.6) and 100% (15/15, 95% CI 76.1-100), respectively. Both fecal and water isolates showed 100% resistance to ampicillin, tetracycline, and nalidixic acid. Resistance to other antibiotics was also found to be high. Multidrug- resistance (MDR) was unveiled in all fecal (58/58) and water (15/15) isolates. MAR index ranged from 0.33 to 0.67 in all recovered isolates. Both fecal and water E. coli isolates harbored blaTEM, tetA, sul1, and sul2 genes. The resistance genes in MDR E. coli in live bird markets might transmit from ducks to humans and they, therefore local authorities should consider this issue a major public health risk.

A feeding trial was conducted using two-hundred-day-old male Ross-308 broiler chickens to evaluate the effect of multi-enzyme (Natuzyme®) on flock uniformity, some haematological and serum biochemical indices, and nutrient retention in broiler chickens fed low energy and protein (LEP) diets. The birds were randomly assigned to four experimental groups of 50 birds each in a completely randomized design. There were five replicates for each treatment group, with 10 chicks per replicate. The first group (positive control/PC) received a standard diet without multi-enzyme supplementation; whereas the LEP0, LEP0.25 and LEP0.50 groups received low-energy-protein diet (LEP) supplemented with multi-enzyme at 0 (negative control), 0.25, and 0.50 g/kg feed, respectively. The PC group received a standard diet having energy and protein of (3000 kcal/kg and 23%) and  (3200 kcal/kg and 20%) at starter and finisher phases respectively. Other groups received LEP diets having energy and protein of the standard diet decreased by 100 kcal/kg and 0.60% both at starter and finisher phases. The feeding trial lasted for 42 days. On days 21 and 42 of the experiment, birds under the LEP0  and LEP0.25 groups had lower (P < 0.05) flock uniformity compared to those of PC and LEP0.50 groups. There was no significant effect of the dietary treatments on haematological and serum biochemical indices of broiler chickens. Birds fed LEP0 and LEP0.25 diets had significantly (P < 0.05) low metabolizable energy (ME), crude fiber (CF) and crude protein (CP) retention compared with the PC group. On the other hand, Broiler chickens offered the LEP0.50 diet had improved (P < 0.05) apparent ME, CF and CP retention.  Results of the study suggest that multi-enzyme supplementation at 0.50 g/kg to low energy and protein broiler chicken diet improved flock uniformity as well as metabolizable energy, CF and protein retention without adverse effects on haematological indices and serum, metabolites.

Lysozyme activity is one of the nonspecific immunity parameters measured by changing the amount of adsorption at different times. The objective of the present study was to compare five non-linear models including Gompertz, Richards, Logistic, Lopez, and Weilbull to describe the cumulative plasma lysozyme activity in quails. In total 1364 plasma samples (1004 females and 360 males) were collected and the cumulative lysozyme activity was calculated by turbidimetric method assay in Micrococcus luteus. The goodness-of-fit of models was compared according to different criteria of Maximum log-likelihood, Akaike information criterion, Mean square error, and Bayesian information criterion. The results showed that the Gompertz model was the best model for describing of decreasing cumulative pattern of lysozyme activity in female and male quails and provided satisfactory predictions of lysozyme activity at different times (30, 60, 90, 120, 150, 180, 210, 240, 270, 300 seconds). The parameters of all models were higher in females than males except for the k parameter which was greater in the males. Male quails had higher values for time and lysozyme activity than females at inflection points, whereas the absolute growth rate in 30, 150, and 300 seconds was predicted higher in female quails. In conclusion, the Gompertz model can be used accurately to evaluate cumulative lysozyme activity patterns in both sexes of quails.

Enterococci cause meat and environmental contamination during slaughter time. In this study, virulence and antimicrobial resistance (AMR) characteristics of enterococci isolated from chickens were determined. A total of 107 cloacal swabs of chickens were inoculated onto Slanetz and Bartley agar and incubated at 37ºC for 24-48 h. Gram staining, catalase, and hemolytic tests were done. AMR was determined using the disc diffusion technique against twelve antimicrobials. Molecular detection of AMR genes: blaZ, aphA, aacA-aphD, ermB, tetL, tetM, and vanC, and virulence factors: agrBEfs, efaAEfs, esp, gelE, and hyl were done on selected isolates using PCR. Ninety-five isolates were Enterococcus species. The isolates showed resistance to tetracycline, cefoxitin, amoxicillin, and imipenem and possessed tetL, tetM, ermB, aphA, vanC, aaca-aphD resistance and gelE, agrBef, efaAfs, espfs and hyl virulence genes. This is the first detection of AMR and virulence genes in multi-drug resistant enterococci among chickens in the locality. These enterococci could constitute a reservoir of virulence and resistance properties which are of animal and public health concern.

This study was conducted to evaluate the effects of feed form (FF) and dietary supplements on performance, immune system, cecal microflora, and intestinal morphology in broiler chickens. A total of 960 one-day-old Ross 308 mixed-sex chickens were distributed to 8 treatments consisting of 6 replicates (20 birds/pen). The experimental design was a 2×4 factorial arrangement of treatments evaluating two feed forms (mash or pellet) and dietary supplements [without a supplement, Lactobacillus acidophilus (L. acidophilus), Bacillus subtilus (B. subtilus), and Avilamycin (an antibiotic)]. Considering the main effects, dietary supplements and pellet diets significantly improved growth performance parameters (FI, BWG, and FCR) compared to the other treatments. Birds fed with a pellet diet had a reduced relative weight of the gizzard and pancreas, increased villus height, and gained the relative weight of the liver and small intestinal. Regardless of the FF, B. subtilis supplementation tended to greater villus height, lower crypt depth, and higher villus height to crypt depth ratio compared to other groups. Birds fed with mash diets supplemented with L. acidophilus and B. subtilis and a pelleted diet supplemented B. subtilis had higher villus height, goblet cell, and Lactobacillus population in the gut compared to the other treatments. Probiotics supplementation reduced the percentage of heterophils compared to other diets. The significant interaction between FF and dietary supplements showed that L. acidophilus in the mash diet tended to enhance the percentage of lymphocytes and reduce the heterophil to lymphocyte ratio compared to the pelleted diet. The main factors had no significant effect on anti-SRBC antibody titer. The results from this study indicated that the probiotic L. acidophilus and B. subtilis used in the mash diet may serve as alternatives to an antibiotic.

The number of eggs produced in a given period (egg production rate) is an important trait in layers that change over time and can be presented as a curve. This study aimed to fit the weekly egg production data of Khazak indigenous hens using non-linear regression models and to select an appropriate model for describing the egg production curve for this bird. Biweekly egg production of 144 laying hens over 52 weeks of egg production was used to evaluate the egg production curve. Seven non-linear models (Gamma, McNally, Compartmental II, Nelder, Yang, Lokhorst, and Narushin-Takma) were fitted to egg production data. The four goodness fit criteria (Akaike’ s information criterion, Mean square error, Log Likelihood, and Bayesian information criterion) were used to compare the models. The results of the goodness of fit criteria showed that the Narushin-Takma and Yang models were the best and worst models, respectively, for describing the egg production curve of Khazak hens. The time and egg production at the peak with the Narushin-Takma model was similar to the actual values, and this model was significantly better than other studied models. The correlation between actual and predicted egg production indicated that the Narushin-Takma model could accurately predict the egg production of this breed. As a result, the Narushin-Takma model can be used to predict the egg production curve of Khazak hens in breeding programs and nutritional management.

This study evaluated the effects of different sources of insoluble fiber at different cage densities on egg performance, egg quality, tibia characteristics, and cecal microbial population of 70-week-old Hy-Line W-36 for 10 weeks. A total of 120 laying hens were allocated to six treatments, including control (CTL) and two sources of insoluble fiber (sugarcane bagasse (SB) and sunflower hulls (SFH) in 5 % of diet) at two stock densities (3 and 5 hens per cage) with five replicates. Dietary inclusion of SB decreased average daily feed intake (ADFI) and egg production (EP), but improved egg weight (EW), egg mass (EM) and feed conversion ratio (FCR) compared to the birds fed SFH. High stock density reduced ADFI, EP, and EW, but increased FCR. Egg quality parameters such as Haugh unit, shell strength, shell thickness, percentage of shell, percentage of yolk, percentage of white and yolk color, and tibia characteristics of laying hens were not affected by insoluble fiber, stock density, or their interactions. High stock density–challenged hens had higher plasma corticosterone levels, but lower feather scores compared to the normal stock density hens (P < 0.05. Besides, subjecting hens to high stocking density decreased populations of Lactobacillus spp. and increased the cecal population of E. coli compared to the control group (P < 0.05). The inclusion of SFH and SB in layer diets, however, increased populations of Lactobacillus spp. and decreased the cecal population of coliforms and E. coli compared to birds in the CTL group. Therefore, dietary inclusion of insoluble fiber, especially sugarcane bagasse,  can be a useful method to improve  productive performance and cecal microbial population of old laying.

The recognition that egg volume variation has widespread implications in avian biology led us to test the accuracy and precision of the most commonly used egg volume determination methods. As a benchmark for the tests, we used real egg volume values determined by water submersion. We identified some evident limitations of this approach and attempted to improve the method by using distilled water and accurate temperature correction. Starting from the assumption that our methodological proposals can effectively improve the accuracy of egg volume measurements, we compared the outcomes with two widely used volume estimation methods based on Hoyt’s equation and Troscianko software estimate for five gallinaceous bird species (forty eggs from each species). We found that Hoyt’s and Troscianko’s egg volume estimation methods strongly correlate with our volume measurements. Despite the highly significant and relatively high values of coefficients of determination, further analyses reveal some important differences among the methods.

This study was conducted to estimate digestible arginine (Arg) requirements for performance and egg quality parameters in Hy-Line W-36 laying hens from 40 to 46 weeks of age. A total of 150 laying hens were arranged in a completely randomized design with 5 treatments, 5 replicates and 6 hens in each. These treatments included 0.81, 0.86, 0.91, 0.96, and 1.01 % digestible Arg. At the end of experiment, data were obtained in performance, egg quality, and quantity parameters as well as plasma levels of cholesterol, uric acid, globulin, and insulin-like growth factor (IGF-1). Results have shown that feed conversion ratio, egg production, and egg mass improved by supplementing 0.86 digestible Arg in the diet compared to other treatments (P < 0.05). Moreover, these items significantly affected by the interaction of treatments and weeks. In the last three weeks of this experiment, the use of 0.86, 0.91, 0.96, and 1.01 % digestible Arg significantly increased egg mass and egg roduction. Plasma concentrations of globulin, cholesterol, and uric acid were not affected by dietary Arg levels. However, a significant increase in plasma IGF-1 was shown by supplementation of % 0.91 Arg (P < 0.05). Based on quadratic equations, the optimum levels of digestible Arg for egg production, egg mass, feed conversion ratio, and IGF-1 were 0.917, 0.917, 0.908, and 0.970%, respectively.

This study was conducted to investigate the effect of licorice (Glycyrrhizaglabra) extract, Active-mos®prebiotic, and flavomycin antibiotic on performance, egg quality, and body mass status in the pre and early laying periods. A total of 180 Leghorn pullets (Hy-line W-36), were assigned into 6 treatments (5 cages/treatment, 6 pullets/cage) in a completely randomized design. The experimental treatments included control (feed additive-free- diet), and control supplemented by licorice extract (5 and 10 g/kg of diet; as LIEX5 and LIEX10, respectively), flavomycin antibiotic (400 and 650 mg/kg of diet; as FL400 and FL650, respectively), and Active-mos®prebiotic (1 kg/ton of diet; as ACPR). Birds were raised in a cage-layer facility. Body weight, feed intake, and feed conversion ratio were determined weekly. Body mass index was recorded before and after using the treatments. Also, the growth, egg quality, egg cholesterol, serum cholesterol, and triglyceride were tested. During weeks 18 to 19 of age, birds received control, FL650, and ACPR treatments showed greater feed intake compared to LIEX10. The body weight of birds that received FL400 diet was greater than LIEX5 and ACPR treatments at weeks 17 to 19 of age. All treatments, except for ACPR, decreased serum cholesterol compared with the control treatment (P < 0.05). No significant effect on feed conversion ratio, egg production, and body mass index was observed by treatments throughout the study (17-25 wk). Furthermore, there was no significant effect of treatments on the eggs' internal and external quality status, egg cholesterol, and serum triglyceride by treatments. However, more research is needed on the use of licorice extract and prebiotics as antibiotic alternatives and their effects on the body mass index in laying hens during pre- and early-laying periods.

This study was conducted to evaluate the effects of dietary levels of milk thistle (MTEO), or nettle essential oils (NEO) on production performance, egg quality and some serum metabolites of white layer hens (Hy-line W-36) aged 60 weeks. A total of 90 birds were randomly assigned to five groups with six replicates of three hens each to study the impact of five dietary treatments consisting of control (as basal diet) and dietary supplementation of different levels of MTEO and NEO (100 and 200 mg/kg). During the experiment period, birds had free accece to feed and water. Dietary supplementation of NEO and 200 mg/kg of MTEO improved egg weight compared to birds that received 100 mg/kg of MTEO (P < 0.05). Also, egg production was greater in 200 mg/kg MTEO treatment than those of birds under control and 100 mg/kg of NEO. Adding MTEO and NEO to the diet exhibited no significant influence on egg mass, feed conversion ratio , and feed intake in laying hens. No change in egg quality characteristics and serum parameters was found in birds fed with MTEO- and NEO-supplemented diets. Diets supplemented with 200 mg/kg of MTEO decreased the percentage of heterophils and heterophil to lymphocyte ratio when compared to control and 200 mg/kg of NEO (P < 0.05). In conclusion, dosage of 200 mg/kg of MTEO could be considered as an dietary feed additive to improve the egg production and immune response in laying hens.