Age Of Birds Research Articles

Sero-Conversion Status of Different Breeds of Chickens Vaccinated With Newcastle Disease I2 Vaccine Type around Hawassa, Ethiopia

Chickens are vaccinated with live attenuated and inactivated vaccines in order to control Newcastle disease (ND). The vaccine can be administered by eye drop, aerosol or drinking water. Humoral antibodies usually appear within 6 to 10 days after vaccination in the serum and also locally in the upper respiratory tract and in the intestine. The efficacy of vaccinations can be estimated best with challenge experiments but they are expensive and time consuming. For the current study, a cross sectional study was conducted to determine the sero-conversion status of ND I-2 vaccine type provided to chicken reared in intensive, semi-intensive and extensive farms in Sidama region, Ethiopia. Of the total 401 samples collected from 29 various flock sizes 363(90.5%) were protective at individual bird level; whereas at flock level 86.2% (25/29) were met above 80% protection. Of 29 flocks 12 (42.4%) flocks were found 100% protective from the disease. The CV% varied between 21.2% and 122.3 percent among the flocks. The uniformity of average antibody titer for Bovans breed (CV%: 56.7) was comparatively better followed by Sasso (CV%: 69.2), Local breed (CV%: 73.1) and mixed breeds (CV%: 83). The overall average minimum, maximum and mean antibody titer for this study was 1179.8, 13840.1 and 5945, respectively. However, the minimum and maximum antibody titer for this study was 37.4 for Sasso breed with the age of 8 months and 20465.8 for mixed type of breed with the age of 12 months respectively. Significant antibody titer variation was observed among Breeds (p=0.018) and Ages (p=0.001) of the birds in this study. In general, the vaccination scheme for the current study revealed ND I-2 vaccine type was effective in protecting the chickens from the disease in respective of the age of birds at vaccination although the pattern of uniformity for antibody production is variably interrupted among the flocks.

Elevated lead (Pb) in urban European starling (Sturnus vulgaris) feathers is not correlated to physiology or behavior

Urbanization is rapidly changing the environment and creating new challenges in the lives of animals across the globe. Anthropogenic contaminants—like heavy metals—can persist within the environment for prolonged periods of time and present a widespread problem for those living near contaminated areas. Lead (Pb) was a commonly used heavy metal that continues to threaten the health of all organisms despite being phased out, especially in urban areas where historical use was more common. In this study, a common urban-adapter, the European starling (Sturnus vulgaris), was trapped to explore whether feather Pb burden is greater in birds from urban habitats than rural habitats, as well as whether Pb burdens were correlated with behavior, physiology, and feather development. Across four sites (two rural and two urban), soil Pb concentrations were measured and 197 free-living starlings were captured to measure feather Pb concentrations. Using linear mixed models, this study found that urban starling nestlings had elevated feather Pb burdens compared to rural nestlings. In contrast, there was no correlation between Pb and urbanization in adult birds whose exposure to Pb may reflect a larger spatial range compared to nestlings. For both nestlings and adults, feather Pb was uncorrelated to corticosterone, testosterone, aggressive behavior, or feather growth rates. These findings suggest that starlings may be a useful biomonitoring tool to detect Pb in the local environment, however, the age and spatial range of birds is a critical consideration in applying this tool. Further work is needed to understand the intricate relationship between heavy metals, behavior, morphological development, and physiology in free-living organisms.

Colony attendance and moult pattern of Cory's Shearwaters (Calonectris borealis) differing in breeding status and age

Migratory birds must fit three costly life‐history events within the annual cycle, reproduction, moult and migration, to minimize their overlap and maximize survival and breeding success. However, some seabirds, such as Cory's Shearwater Calonectris borealis, overlap body moult and breeding, with flight feather renewal occurring in late chick‐rearing. In contrast, the moult patterns of non‐breeding adult (sabbatical) and immature Cory's Shearwaters, which also attend the colony during the breeding season, remain poorly understood. Furthermore, the potential implications of life‐stage and breeding status trade‐offs on moult status and colony attendance in non‐breeders has rarely been investigated. Surveying different areas within one colony between June and September 2013 and 2014, we studied the age and breeding status composition of birds attending the breeding colony and scored moult of their body (breast and upper‐neck), wing and tail feathers. We found that in addition to breeders (n = 165), 57.6% of the birds (n = 389) attending the colony were 4‐ to 10‐year‐old immatures (n = 132) and adult sabbatical shearwaters (n = 92). Sabbaticals and 8‐ to 10‐year‐old immatures (n = 28) were present at the colony during incubation, whereas only three sabbatical birds and no 8‐ to 10‐year‐old immatures were captured in late chick‐rearing. Conversely, 4‐ to 7‐year‐old immatures arrived later in the season but were still present in late chick‐rearing. Sabbatical and 8‐ to 10‐year‐old immatures were moulting body feathers at the same time as adult breeders, whereas, among 4‐ to 7‐year‐old immatures, older birds moulted earlier than younger birds. A larger proportion of sabbatical birds were replacing tail feathers compared with adult breeders. However, there was no evidence that sabbaticals or 8‐ to 10‐year‐old immatures differed in wing moult from adult breeders until August. Overall, our study shows that colony attendance by non‐breeding adults and immatures is widespread in this population. The synchronous moult schedule of flight and body feathers across age groups at different life‐history stages may suggest that this aspect of moult is controlled by environmental conditions.

STATE OF POPULATIONS AND BREEDING BIOLOGY OF THE HORNED PUFFIN (<i>FRATERCULA CORNICULATA</i> ALCIDAE, CHARADRIIFORMES) IN THE NORTHERN PART OF THE SEA OF OKHOTSK

The breeding biology of the Horned Puffin, Fratercula corniculata, was studied in 1989–2019 on Talan Island, Tauiskaya Bay, Sea of Okhotsk. Even though the estimates of the population size of the Horned Puffin made in the early 1990s and 2007–2008 (90–100 and 75–112 thousand individuals, respectively) failed to reveal its dynamics due to different study methods applied, data on the nesting density in these periods indicated its increase by more than 30%. In subsequent years, higher bird densities were recorded on the surface of model screes. Taking into account these data, the maximum numbers of horned puffins on the island could reach 166 thousand individuals. Depending on ice cover conditions, the dates of the onset of egg laying varied between June 6 in 1990 and June 17–18 in 1987, 1999 and 2001, the average long-term date being June 11. Chicks in different years started hatching between July 17 to 29, the average long-term being July 22. The weight of hatchlings varied from 35 to 53 g (mean 47.2). The average weight of monthly chicks in 1999–2006 ranged from 145 to 329 g, in some individuals from 80 to 410 g. The average age of the young birds captured on the ground was 44.7 days. The first individuals were recorded in different years at the end of August (August 27–30) and at the beginning of September (September 2). According to indirect estimates, fledglings left nest burrows between September 10 and 20, to end in late September to early October. The average weight of fledglings heading to the sea in 1987, 1988, 1989 and 1991 was 349, 338, 347 and 318 g, respectively. The wing length varied from 153 to 156 mm. The reproductive success of horned puffins varied from 10.3 to 90.5% (on average 56.4%), the hatching success from 19.8 to 95.2% (on average 75.5%), the fledging success from 26.7 to 100% (on average 74.6%). In the long-term aspect, the breeding success was most often quite high, with the exception of 2001, 2009–2012 and 2014–2015, when this indicator was lower than the long-term average. Among terrestrial mammals, red foxes cause the main threat to adult horned puffins living on the island, as well as to their clutches and chicks descending to the sea, but foxes fail not render a significant impact on the state of the horned puffin population. Due to their small numbers, these predators control only a certain parts of the island, while horned puffins are dispersed almost throughout its territory, where in most cases they are safe from fox predation. Voles act as utilizers of already abandoned eggs. Slaty-backed gulls and ravens do not attack adult horned puffins, but willingly eat adult birds found dead, as well as dead or still alive chicks during their descent to the sea. Adult birds are also taken, albeit rarely, by Steller’s sea eagles.

Zebra finches have style: Nest morphology is repeatable and associated with experience

We investigated whether birds build nests in repeatable styles and, if so, whether styles were associated with past nest-building experience. Laboratory, captive bred zebra finches in an Experimental group were given nest-building experience, whereas, birds in a Control group were not. Each pair (n= 20) then built four nests that underwent image analyses for nest size, geometric shape and entrance orientation. Birds built nests in repeatable styles, with lower morphometric variation among nests built by the same pair and higher morphometric variation among nests built by different pairs. Morphology was not associated with construction time, body weight, nor age of birds. We found lower morphometric variation among nests built by the Experimental group, which also used less material to build nests compared to the Control group. Prior experience may therefore have been advantageous, as learning to reduce material usage while achieving a similar product (nest) may have lowered building costs.

Graded levels of Eimeria infection linearly reduced the growth performance, altered the intestinal health, and delayed the onset of egg production of Hy-Line W-36 laying hens when infected at the prelay stage

The aim of this experiment was to investigate how different levels of Eimeria infection affect the performance, intestinal health, oxidative status, and egg production of Hy-Line W-36 pullets and laying hens. Three hundred and sixty Hy-Line W-36 pullets, aged 15 wk, were randomly distributed into 5 treatment groups, each comprising 6 replicates and a nonchallenged control. At 15 wk, pullets were inoculated with different levels of mixed Eimeria species as high-dose, medium-high, medium-low, and low-dose treatments. The growth performance and average daily feed intake (ADFI) were measured from 0- to 18-days postinoculation (DPI), whereas hen day egg production (HDEP) was recorded from wk 19. The markers of gastrointestinal health and oxidative status were measured at 6 DPI, 14 DPI, and 23 wk of age. The findings revealed a significant linear reduction in growth performance in response to increasedEimeriachallenge dosage on 6 and 14 DPI (P < 0.0001,P-L < 0.0001). An interaction between thegraded level of Eimeriainfection and DPI was observed for ADFI. The challenged pullets showed a reduction in ADFI starting at 4 DPI, which persisted until 14 DPI, when ADFI recovered back to normal. The most significant drop in feed intake was observed in 6 DPI in all the Eimeria-infected groups. The markers of gastrointestinal health (gastrointestinal permeability and tight junction proteins) were upregulated in challenged pullets because of infection, whereas the relative mRNA expression of key nutrient transporters was downregulated following infection on 6 and 14 DPI (P < 0.05). As a result of an infection on 6 DPI, the oxidative equilibrium was shifted toward the oxidative stress, and at the same time, upregulation of proinflammatory and inflammatory cytokines was observed (P < 0.05). An interaction between the Eimeria challenge dosage and bird age was observed for HDEP (P=0.0427). The pullets infected with Eimeria started to lay eggs later than the Control birds. However, the HDEP of the challenged groups became similar to Control only at wk 22, 3 wk after laying eggs. In conclusion, coccidiosis reduced growth performance, altered gastrointestinal health, induced oxidative stress, and delayed egg production when infected at the prelay stage of pullets and negatively impacted the laying hens' overall performance.

Temporal stability and community assembly mechanisms in healthy broiler cecum.

In recent years, there has been an unprecedented advancement in in situ analytical approaches that contribute to the mechanistic understanding of microbial communities by explicitly incorporating ecology and studying their assembly. In this study, we have analyzed the temporal profiles of the healthy broiler cecal microbiome from day 3 to day 35 to recover the stable and varying components of microbial communities. During this period, the broilers were fed three different diets chronologically, and therefore, we have recovered signature microbial species that dominate during each dietary regime. Since broilers were raised in multiple pens, we have also parameterized these as an environmental condition to explore microbial niches and their overlap. All of these analyses were performed in view of different parameters such as body weight (BW-mean), feed intake (FI), feed conversion ratio (FCR), and age (days) to link them to a subset of microbes that these parameters have a bearing upon. We found that gut microbial communities exhibited strong and statistically significant specificity for several environmental variables. Through regression models, genera that positively/negatively correlate with the bird's age were identified. Some short-chain fatty acids (SCFAs)-producing bacteria, including Izemoplasmatales, Gastranaerophilales, and Roseburia, have a positive correlation with age. Certain pathogens, such as Escherichia-Shigella, Sporomusa, Campylobacter, and Enterococcus, negatively correlated with the bird's age, which indicated a high disease risk in the initial days. Moreover, the majority of pathways involved in amino acid biosynthesis were also positively correlated with the bird's age. Some probiotic genera associated with improved performance included Oscillospirales; UCG-010, Shuttleworthia, Bifidobacterium, and Butyricicoccaceae; UCG-009. In general, predicted antimicrobial resistance genes (piARGs) contributed at a stable level, but there was a slight increase in abundance when the diet was changed. To the best of the authors' knowledge, this is one of the first studies looking at the stability, complexity, and ecology of natural broiler microbiota development in a temporal setting.

Energy utilization and requirement of broiler breeders during the production phase

This study aimed to evaluate energy utilization and propose models for metabolizable and net energy requirements in broiler breeders during the egg production phase. Sixty Cobb500 broiler breeders aged between 29 and 65 wk were randomly assigned to 3 feeding levels. At each age, 6 birds were adapted for 8 d to 3 levels of metabolizable energy intake (MEi), established based on the amount of feed allocated: 1) the amount of feed recommended in the guideline, 2) 25% above, and 3) 25% below. The birds were housed in respirometry chambers for 6 d (1 adaptation, 4 feeding state, 1 fasting) to measure oxygen consumption and carbon dioxide production to calculate heat production (HP) and fasting HP (FHP). Daily measurements of feed intake, egg weight, egg production, and total excreta were recorded. Variables of MEi, HP, and retained energy (RE) in the egg were calculated, while RE in the body and its partitioning into fat and protein in the egg and body were calculated from MEi, total HP (THP), and RE in the egg. Statistical analysis involved linear regression of multiple factors with MEi and age (categorical) as the independent variables. Pearson correlation analysis was conducted to investigate the relationship between visceral mass and the evaluated variables. The study proposed mixed models for developing models of energy requirements for both metabolizable (ME) and net systems (NE). The study found that FHP (average 259 ± 20.08 kJ/kg0.75*d) remained constant throughout the production cycle regardless of the MEi level (P > 0.05). The efficiency of energy utilization for depositing protein and fat in the body changed with the bird's age. The lower error model was considered to select ME requirements for maintenance, egg, and gain efficiencies, disregarding the effect of age. The efficiencies were 0.89, 0.78, and 0.80 for maintenance, gain, and egg production, respectively. The NE was unaffected by age and showed a lower error than the ME model. The NE system was found to be more accurate in expressing the energy requirements of broiler breeders.

Age effects in Darwin’s finches: older males build more concealed nests in areas with more heterospecific singing neighbors

Nesting success tends to increase with age in birds, in part because older birds select more concealed nest sites based on experience and/or an assessment of prevailing predation risk. In general, greater plant diversity is associated with more biodiversity and more vegetation cover. Here, we ask if older Darwin’s finch males nest in areas with greater vegetation cover and if these nest sites also have greater avian species diversity assessed using song. We compared patterns in Darwin’s Small Tree Finch (Camarhynchus parvulus) and Darwin’s Small Ground Finch (Geospiza fuliginosa) as males build the nest in both systems. We measured vegetation cover, nesting height, and con- vs. heterospecific songs per minute at 55 nests (22 C. parvulus, 33 G. fuliginosa). As expected, in both species, older males built nests in areas with more vegetation cover and these nests had less predation. A novel finding is that nests of older males also had more heterospecific singing neighbors. Future research could test whether older males outcompete younger males for access to preferred nest sites that are more concealed and sustain a greater local biodiversity. The findings also raise questions about the ontogenetic and fitness consequences of different acoustical experiences for developing nestlings inside the nest.

First molecular detection of avian polyomavirus from captive psittacine birds in Bangladesh, together with confirmation of beak and feather disease virus co-infection.

Avian polyomavirus (APV) is an emerging pathogen in many parts of the world responsible for causing significant mortality in captive psittacine birds. The virus spreads slowly, and transboundary movement of birds is one of the potential risk factors for the virus introduction in the naïve population. Bangladesh allows the import of birds, however there is currently no surveillance to screen for APV. Since we confirmed beak and feather disease virus (BFDV) infection in the captive population in our earlier investigation, we hypothesized that APV may also be circulating in Bangladesh. Feather samples were collected from 100 birds (90 psittacine and 10 non-psittacine). The polymerase chain reaction (PCR) was used to detect viral DNA together with sequencing and phylogenetic analysis. This first pilot study confirmed the presence (7%, 7/100) of APV in captive psittacine birds of Bangladesh and almost half (4%, 4/100) of the APV positive birds had the BFDV co-infection. All the PCR-positive birds were asymptomatic and found in live bird markets (LBMs). No significant variation was observed in the detection rate considering species (P = 0.94), age (P = 0.39) or sex (P = 0.55) of birds. According to the results of the phylogenetic study, the APV isolates found in Bangladesh appear to be unrelated to isolates from other geographical areas. These findings provide an evidence of APV circulating in Bangladesh, with or without the co-infection of BFDV. Additional studies are needed to investigate the occurrence of APV/BFDV co-infection in the larger population of Bangladesh and in countries where transboundary bird interaction with Bangladesh may be possible.

Insight in a behaviour of Central European Red Kites wintering in Italy

Migration and over-wintering strategy of raptors can be influenced by many factors such as sex, age and experience of birds, habitat variability and food availability. Based on the telemetry data of nine Red Kites (Milvus milvus), we observed in situ their wintering grounds in southern Italy during winter 2019/2020. Red Kites originated from Austria and the Czech Republic arrived to their wintering grounds from 10th September to 5th December 2019 and departed between 9th February and 7th May 2020. Tagged Kites stayed in their wintering grounds from 73 to 207 days (mean 135±46 SD). These birds occupied home range and the core area from 39 to 9,351 km2 (KDE 95%; mean 3,591±3,460 SD) and 6 to 1,998 km2 (KDE 50%; mean 566±483 SD), respectively. We observed a total of 242 Red Kites at nine communal roost sites (min. = 14, max. = 45 individuals) used by tagged Red Kites. Roosts were situated at an average altitude of 630 m above sea level. Agricultural countryside with small or large fields, small or large forest patches, meadows, pastures, sheep or cattle farms surrounded areas around communal roosts of Red Kites.

Influence of weight at hatching on weekly weight of broiler chickens

Broiler production is concerned with raising birds that reach market weight within a short time interval, and efforts are geared at indices that can accurately predict the future growth performance of birds based on their initial measurements. This study investigated the relationship between initial weight taken at hatch and its influence on subsequent weights of birds. Newly hatched day-old chicks were obtained from a reputable hatchery in Ibadan, Oyo state. It comprised of chicks from four different commercial broiler strains (Arbor Acre, Cobb, Marshall and Ross). The chicks were tagged for proper identification and weighed and records of their weekly weights taken over ten (10) week period of the study. At the end of the study, a total of 216 broiler chicks comprising Arbor Acre (48), Cobb (52), Marshall (60) and Ross (56) were analysed. Weekly weight progressively increased with increasing age of the birds, while weight gain increased across the weeks, with a decline and a further rise in values reflecting the different stages of growth. The population was fairly homogenous at the early stages but was later moderately varied with increasing age of birds. There was a highly significant (P&lt;0.001) positive correlation amongst all the weights studied but strongest values were recorded on measurements that are contiguously close. Despite the fact that regression of weekly weights was highly statistically significant on initial weight, it is noteworthy that initial weight as predictors of weekly weight had the best fit on the first weekly weight, but the influence of initial weight consistently decreased with increasing age of the broiler birds. This study revealed that initial weight of broiler birds at hatch is a good predictor of future weight of the birds and can be used to model the future growth performances of the birds.

Detection and Molecular Characterization of Avibacterium paragallinarum from Poultry

Background: Infectious coryza is an acute, highly contagious respiratory disease of chickens caused by Avibacterium paragallinarum causing heavy economical loss to the poultry farmers. The laboratory diagnosis of Av. paragallinarum infection is based mainly on conventional methods such as isolation and identification of the organisms. In modern poultry industry, the rapid diagnosis of Av. paragallinarum is essential along with detection of variation among the serotypes. Methods: A total of 128 samples (viz., heart blood swabs, tracheal, eye and infra orbital swabs) suspected for infectious coryza were screened for the presence of Av. paragallinarum by isolation and molecular characterization. Information regarding farm/flock strength, age of birds, method of rearing, production performance, clinical symptoms manifested and mortality patterns from various organized poultry farms were recorded. A total of five isolates of Av. paragallinarum have been recovered from suspected materials processed for isolation. Two isolates were sequenced and analysed. Result: All the isolates showed same biochemical characters but exhibited variability in the fermentation of mannose, mannitol and sorbitol. The nucleotide variation of Av. paragallinarum present in Indian subcontinent differs in their virulence and pathogenicity. The study was also focused for the molecular characterisation of Avibacterium species from different isolates. Though the clinical signs and gross pathological signs were similar, the nucleotide variation between isolates was observed. Sequencing of ‘hagA’ gene showed that the two isolates were closely related to the strains of China, Australia, Mexico and India which shared 94-100% homology.

Economic Growing Quantity Model with Mortality in Newborn Items and Inhibition Cost of Ammonia Production under All-Units Discount Policy

The amount of global ammonia (NH3) emissions is growing continuously, similar to the damage to the environment, particularly humans and animals, caused by those emissions. Various problems derived from pollution by ammonia emissions have attracted increasing attention in recent years. In particular, accumulation of ammonia in poultry farms is a concern for the poultry industry as it can lead to possible damage due to reduced bird performance, damage to the respiratory tract and skin of birds, and thus loss of customers. As birds age, ammonia production increases due to factors such as feeding and mobility, requiring the application of solutions to reduce it such as the use of fans, feed supplements, and temperature adjustments to improve bird health. These solutions impose additional costs on poultry farms to combat ammonia emissions. This study presents a general economic growing quantity (EGQ) model that includes the cost of inhibition of ammonia production during the growing period. In addition, the model is formulated under an all-units discount policy, where the price of newborn items is related to the size of the order purchased from the supplier. Furthermore, the model assumed that some newborn items are dead when the lot is received because of stress experiences and incidents during the catching, loading, transportation, and unloading. Finally, two versions of the proposed general EGQ model are presented: EGQ with no discount and EGQ with known slaughter age.

The impact of a fermented diet including Iraqi probiotics on a few productive characteristics in Chinese ducks

This study was conducted in a private field for duck breeding in Al-Muthanna Governorate from 12/14/2021 to 02/14/2022. A total of 125 one-day-old chicks were reared from Pekingese ducks, with an average weight of 42 g; ducklings were prepared from local markets in Al-Diwaniah Governorate, and chicks were reared at a semi-enclosed hall with dimensions of 25 × 10 m. Chicks were randomly distributed into five treatments; each treatment was three replicates (10 chicks/replicate), placed in 15 Pens, and the area of one pen was 1.5 × 1 m. The experiment treatments were as follows: the control treatment (T1) and other treatments used feed fermentation with Iraqi probiotics Vs. dry feed 25%+75%, 50%+50%, 75%+25% and 100%+0%, for treatments T2, T3, T4 and T5 respectively. The results indicated a significant improvement in the average live body weight, weight gain, feed consumption and feed conversion factor for ducks fed by fermentation with the Iraqi probiotics compared to the control treatment at 4 and 8 weeks of the bird's age. Keywords: feed fermentation, Iraqi probiotics on, productive traits, Chinese ducks

Vaccination of Zoo Birds against West Nile Virus-A Field Study.

West Nile virus (WNV) is known to cause disease and death in humans and various animals worldwide. WNV has circulated in Germany since 2018. In 2020, four birds tested positive for the WNV genome at Zoopark Erfurt (Thuringia). Moreover, virus neutralization assays detected neutralizing antibodies (nAb) against WNV in 28 birds. In addition, nAb against WNV and Usutu virus (USUV) were found in 14 birds. To protect valuable animals and to reduce the risk of viral transmission from birds to humans, we performed a field study on WNV vaccination at the zoo. To conduct the study, 61 birds from the zoo were categorized into three groups and subjected to a vaccination regimen, where each bird received either 1.0 mL, 0.5 mL, or 0.3 mL of a commercial inactivated WNV vaccine three times. The vaccinations were administered at three-week intervals, or as per modified vaccination schedules. Furthermore, 52 birds served as non-vaccinated controls. Adverse vaccination reactions were absent. The greatest increase in nAb titres was observed in birds that received 1.0 mL of vaccine. However, pre-existing antibodies to WNV and USUV appeared to have a major effect on antibody development in all groups and in all bird species, whereas sex and age had no effect. After vaccination, no death was detected in vaccinated birds for more than 1 year.

Comparison of Mixed and Choice Feeding of Whole Wheat (Triticum aestivum) on the Performance of Commercial Broilers

Wheat is the cereal grain of choice for Whole Grain Feeding (WGF) in poultry, despite the fact that globally maize is the most commonly used cereal grain. In this context, in the present study feeding of whole wheat to commercial broilers with two types of feeding systems were used ie. mixed and choice feeding systems of wheat with different levels of replacement with maize by 20, 40, 60, 80 and 100%. The body weight and body weight gain of birds fed with 20% and 40% choice feeding of wheat was found to be the highest (p&lt;0.05). The mean wheat consumption (g/bird) from total feed consumption under choice feeding during 2 to 6 weeks of age in birds fed with 20, 40, 60, 80 and 100% were found to be 363.18, 720.12, 1398.45, 2160.30 and 3202.10, respectively. Birds fed with choice feeding of 40% wheat showed significantly (p&lt;0.05) improved FCR. The highest livability (%) was found in the birds fed with 40% and 100% choice feeding of wheat. The gizzard weight (g) showed non-significant difference among the birds fed with various treatment rations. The highest return over feed cost (in Rs.) was found in the birds fed with 40% choice feeding of wheat. The overall results indicated that choice feeding system is more suitable for better body weight gain and improved FCR as compared to mixed feeding system of whole wheat. Feeding with 40% maize in diet replaced by wheat and offered in separate feeder is more economical and profitable due to higher body weight gain, improved FCR and acceptable mortality.

Influence of sex and rearing method on performance and flock uniformity in broilers-implications for research settings.

Male and female broiler chickens differ in their growth performance, carcass part weights and nutrient requirements. The potential reasons for these differences have been explored by looking at differences in nutrient digestibility, nutrient transporter gene expression as well as gut microbiota populations between male and female birds. Studies have shown that male broilers have higher crude protein requirements compared to female broilers. The expression of monosaccharide and amino acid transporters show conflicting results as expression depends on the interactions between sex and bird age and breed as well as which tissue is sampled. Differences in microbiota populations between the genders were reported which may contribute towards performance differences, however research in this area is limited. The differences observed between the sexes contribute to increased variation in nutrition trials, and the potential to rear birds as equally mixed-sex becomes an option to reduce the variation introduced by the sex effect. Difference in rearing options obviously would only be feasible provided a quick, practical and cost-effective method of sexing birds is available, a topic that is also discussed in this review.

Spatial Variability of External Egg Quality in Vertical Naturally Ventilated Caged Aviaries

External egg quality is an essential parameter of egg production as it relates directly to economic losses. This study evaluated the spatial variability of external egg quality in five naturally ventilated caged vertical aviaries. Differences caused by bird age and thermal and luminous variability within aviaries during winter and summer were analyzed. Data on aviary air temperature, relative humidity, light intensity, and external egg quality were collected at evenly distributed points along the aviary length within three levels of cages. The experimental design was completely randomized in a factorial scheme. In the summer, the highest air temperature and lowest relative humidity were found in central cages, mainly in upper center cages; hens produced eggs with a lower weight and shape index in this area. Similar results were obtained in the winter. In the summer, eggs with lower shell weight and thickness were also produced by hens housed in the central cages, but in the winter, the opposite result was obtained. This study of the spatial variability of external egg quality proved efficient in detecting areas within an aviary with poor quality eggs; improvements to design and management in these areas could help management improve production efficiency and contribute to a sustainable egg supply.

Raising offspring increases ageing: Differences in senescence among three populations of a long-lived seabird, the Atlantic puffin.

Actuarial senescence, the decline of survival with age, is well documented in the wild. Rates of senescence vary widely between taxa, to some extent also between sexes, with the fastest life histories showing the highest rates of senescence. Few studies have investigated differences in senescence among populations of the same species, although such variation is expected from population-level differences in environmental conditions, leading to differences in vital rates and thus life histories. We predict that, within species, populations differing in productivity (suggesting different paces of life) should experience different rates of senescence, but with little or no sexual difference in senescence within populations of monogamous, monomorphic species where the sexes share breeding duties. We compared rates of actuarial senescence among three contrasting populations of the Atlantic puffin Fratercula arctica. The dataset comprised 31 years (1990-2020) of parallel capture-mark-recapture data from three breeding colonies, Isle of May (North Sea), Røst (Norwegian Sea) and Hornøya (Barents Sea), showing contrasting productivities (i.e. annual breeding success) and population trends. We used time elapsed since first capture as a proxy for bird age, and productivity and the winter North Atlantic Oscillation Index (wNAO) as proxies for the environmental conditions experienced by the populations within and outside the breeding season, respectively. In accordance with our predictions, we found that senescence rates differed among the study populations, with no evidence for sexual differences. There was no evidence for an effect of wNAO, but the population with the lowest productivity, Røst, showed the lowest rate of senescence. As a consequence, the negative effect of senescence on the population growth rate (λ) was up to 3-5 times smaller on Røst (Δλ=-0.009) than on the two other colonies. Our findings suggest that environmentally induced differences in senescence rates among populations of a species should be accounted for when predicting effects of climate variation and change on species persistence. There is thus a need for more detailed information on how both actuarial and reproductive senescence influence vital rates of populations of the same species, calling for large-scale comparative studies.