Inclusion of up to 20% Black Soldier Fly larvae meal in broiler chicken diet has a minor effect on caecal microbiota

Background

The Black Soldier Fly larvae (BSFL) are a source of nutrients and bioactive compounds in broiler diets. Some components of the BSFL may serve as a prebiotic or may impact the intestinal microbiota of the broilers by other modes of action, which in turn can affect the health and performance of broilers. Here, we investigate the impact of up to 20% BSFL in broiler diets on the diversity and composition of the broiler's microbiota.

Methods

Four hundred broilers were fed five iso-nutritious experimental diets with increasing levels of BSFL meal reaching 0%, 5%, 10%, 15%, 20% in the finisher diets. Eight caecal content samples coming from each of the eight replicates per treatment were collected at two time points (day 21 and day 42) for DNA extraction and sequencing of the V3-V4 regions using Illumina MiSeq 2 × 300 bp pair-end sequencing with 341f and 805r primers. Analysis of variance and Spearman's correlation were performed, while QIIME2, DADA2, and Calypso were used for data analysis.

Results

When broilers were 21 days of age, the abundance of two groups of sequence variants representing Enterococcus and unclassified Christensenellaceae was significantly lower (p-value = 0.048 and p-value = 0.025, respectively) in the 20% BSFL group compared to the 0% BSFL group. There was no relevant alteration in the microbiota diversity at that stage. On day 42, the Spearman correlation analysis demonstrated that the sequence variants representing the genus Coprococcus showed a negative relationship with the BSFL inclusion levels (p-value = 0.043). The sequence variants representing the genus Roseburia and Dehalobacterium demonstrated a positive relationship with the BSFL dietary inclusion (p-value = 0.0069 and p-value = 0.0034, respectively). There was a reduction in the dissimilarity index (ANOSIM) caused by the 20% BSFL dietary inclusion.

Conclusion

The addition of up to 20% BSFL in broiler diets did not affect the overall caeca microbiota diversity or composition at day 21. On day 42, there was a reduction in the beta diversity caused by the 20% BSFL dietary inclusion. The abundance of the bacterial group Roseburia was increased by the BSFL dietary inclusion, and it may be beneficial to broiler immunity and performance.

An Initial Study on the Use of Machine Learning and Radio Frequency Identification Data for Predicting Health Outcomes in Free-Range Laying Hens

Maintaining the health and welfare of laying hens is key to achieving peak productivity and has become significant for assuring consumer confidence in the industry. Free-range egg production systems represent diverse environments, with a range of challenges that undermine flock performance not experienced in more conventional production systems. These challenges can include increased exposure to parasites and bacterial or viral infection, along with injuries and plumage damage resulting from increased freedom of movement and interaction with flock-mates. The ability to forecast the incidence of these health challenges across the production lifecycle for individual laying hens could result in an opportunity to make significant economic savings. By delivering the opportunity to reduce mortality rates and increase egg laying rates, the implementation of flock monitoring systems can be a viable solution. This study investigates the use of Radio Frequency Identification technologies (RFID) and machine learning to identify production system usage patterns and to forecast the health status for individual hens. Analysis of the underpinning data is presented that focuses on identifying correlations and structure that are significant for explaining the performance of predictive models that are trained on these challenging, highly unbalanced, datasets. A machine learning workflow was developed that incorporates data resampling to overcome the dataset imbalance and the identification/refinement of important data features. The results demonstrate promising performance, with an average 28% of Spotty Liver Disease, 33% round worm, and 33% of tape worm infections correctly predicted at the end of production. The analysis showed that monitoring hens during the early stages of egg production shows similar performance to models trained with data obtained at later periods of egg production. Future work could improve on these initial predictions by incorporating additional data streams to create a more complete view of flock health.

Ascaridia galli eggs obtained from fresh excreta, worm uteri or worms cultured in artificial media differ in embryonation capacity and infectivity

Ascaridia galli infection models use eggs isolated from chicken excreta, worm uteri and worms cultured in artificial media. The aim of this study was to compare the infectivity of A. galli eggs isolated from these sources under two infection regimens. A 3 × 2 factorial arrangement was employed to test the infectivity of A. galli eggs from the three sources and two modes of infection (single or trickle infection). One hundred and fifty-six Isa-Brown one day-old cockerels randomly assigned to the six treatment groups (n = 26) were orally infected with embryonated A. galli eggs obtained from the three A. galli egg sources (worm uteri, excreta or eggs shed in vitro) administered either as single dose of 300 eggs at one day-old or trickle infected with 3 doses of 100 eggs over the first week of life. Twenty-two negative control birds remained uninfected. Eggs obtained from cultured worms or excreta exhibited a higher embryonation capacity (P = 0.003) than eggs obtained from worm uteri. There were higher worm establishment (infectivity) rates from embryonated eggs originating from cultured worms and worm uteri compared with eggs obtained from fresh excreta (P < 0.0001). Trickle infection resulted in a significantly higher total worm burden (P = 0.002), establishment rate (P = 0.002) and excreta egg counts (EEC, P = 0.025) than single infection. Worm length was greater in birds infected with embryonated eggs from excreta than from uteri or cultured worms (P < 0.0001). However, mode of infection did not affect worm length (P = 0.719) and weight (P = 0.945). A strong significant positive linear correlation was observed between EECs and female worm counts at 12 weeks of post infection sampling (r = 0.75; P < 0.0001). Body weight of birds was negatively correlated with both worm burden (r = - 0.21; P < 0.01) and EEC (r = - 0.20; P < 0.05) at 12 weeks post infection. In conclusion, our results show that eggs shed by cultured worms or isolated from worm uteri had greater infective capacity than eggs harvested from excreta and that trickle rather than bolus infection resulted in higher worm establishment. These factors should be taken into account when considering artificial infection protocols for A. galli.

Worm control practices on free-range egg farms in Australia and anthelmintic efficacy against nematodes in naturally infected layer chickens

This study investigated worm control practices by free-range egg farmers and the efficacy of the commercial anthelmintics levamisole (LEV), piperazine (PIP), flubendazole (FLBZ) and fenbendazole (FBZ) against gastrointestinal nematodes on two free-range layer farms in Australia. An online survey comprising 36 questions was designed and implemented using SurveyMonkey. The survey contained questions about participant demographics, farm and flock characteristics, perceived intestinal worm importance, infection monitoring, deworming and other worm control practices. A link for the survey was emailed to free range egg producers from their industry body in December 2019. The anthelmintic efficacy trial was conducted in a total of 229 layers naturally infected with Ascaridia galli, Hetarakis gallinarum, Capillaria spp. and/or tape worms. Chickens received a single oral dose of LEV (28 mg/kg), PIP (100 mg/kg), FBZ (10 mg/kg) or LEV-PIP co-administered at their full individual doses, and FLBZ (Flubenol®), 30 ppm or 60 ppm) in the feed over 7 days. Anthelmintic efficacies were estimated by both worm count reduction (WCR %) and excreta egg count reduction (EECR %) tests 10 days after start of treatment. The survey with a response rate of 16/203, revealed that worm infection was of moderate concern to the producers and the majority (68%) felt that the current anthelmintics work effectively. The level of understanding of worms, monitoring and control practices did not reveal any major deficiencies of concern. The most commonly used anthelmintic was LEV (73%) followed by PIP (45%). Based on a standard cut-off value (≥90%), LEV, LEV-PIP, and FBZ attained the desired efficacy but PIP exhibited reduced efficacy against immature A. galli (61-85%), all stages of H. gallinarum (42-77%) and Capillaria spp. (25-44%). FLBZ was highly effective against all stages of roundworms and tapeworm infections. Even though there was some association between the efficacies estimated by WCR % and EECR % the latter was poorly associated in the natural infection model and hence does not provide a reasonable alternative for assessing anthelmintic efficacy when immature stages of the lifecycle are included. These results show no evidence of loss of susceptibility to the tested anthelmintics on these farms supporting the perception of producers that participated in the survey that current treatments work effectively. The reduced efficacy of PIP against some species and immature stages is related to its spectrum of activity rather than providing evidence of emerging resistance.

Anthelmintic efficacy evaluation against different developmental stages of Ascaridia galli following individual or group administration in artificially trickle-infected chickens

The efficacy of commercially available anthelmintics against mature and immature stages (including ovicidal effects) of two Australian field isolates of Ascaridia galli was evaluated in two separate experiments. The anthelmintics tested were levamisole (LEV), piperazine (PIP) and flubendazole (FBZ) plus LEV-PIP. A total of 192 artificially trickle-infected young cockerels (96 birds per isolate) were randomized into sixteen experimental groups of 12 cockerels each (7 treatments and 1 untreated control per isolate). Chickens received label-recommended doses of LEV (28 mg/kg), PIP (100 mg/kg) or LEV-PIP co-administered at their full individual doses as a single oral dose or in group drinking water at recommended concentrations of 0.8 mg/ml or 2.5 mg/ml over eight hours for 1 and 2 days respectively and FLBZ (30 ppm) in the feed over 7 days. Anthelmintic efficacies were assessed by worm count reduction (WCR%) and excreta egg count reduction (EECR%) estimated by two methods. Ten days post treatment, all untreated control birds harboured mixed worm population of 10.1 and 12.3/bird for each isolate respectively which was significantly higher (P < 0.0001) than counts in all treatment groups. Luminal or histotrophic larvae comprised 50-57 % of the total worm count. For LEV, PIP and LEV-PIP, individual oral administration provided a somewhat higher efficacy than group medication in drinking water. EECR% values were inconsistent with WCR% and found to be only an indicator of efficacy against adult worms. All developmental stages of the two A. galli isolates were highly susceptible to FLBZ (100 %) followed by LEV-PIP (92.4-100 %) and LEV (87.7-100 %). PIP exhibited good efficacy against adult worms (92-97 %) but reduced efficacy against luminal (79-84 %) and histotrophic (61-72 %) larvae. Embryonation capacity of eggs recovered from worms expelled after treatment with LEV (47-54 %), PIP (44-54 %) or LEV-PIP (45-48 %) did not differ from those from untreated birds (50-51 %) whereas eggs from FLBZ treated worms had a significantly lower (P < 0.05) capacity to embryonate (≤ 2 %). Put together, our results demonstrate no evidence of resistance of the test A. galli isolates to the tested anthelmintics but a significant advantage of FLBZ, followed by LEV-PIP and LEV over PIP in the control of A. galli, specifically with regard to immature stages. A. galli worms expelled after treatment with LEV, PIP or their combination, but not FLBZ contain viable eggs. This has epidemiological implications and may also provide an option for isolating eggs from mature worms for A. galli propagation experiments without having to sacrifice birds.

Ascaridia galli challenge model for worm propagation in young chickens with or without immunosuppression

With the continued growth of free-range egg production, the importance of the chicken roundworm Ascaridia galli is increasing. Investigations into this parasite would be facilitated by the availability of characterised strains and clear guidelines on optimal methods of multiplication and maintenance. Currently, there is lack of well-defined in vivo models for maintaining A. galli and the potential of using host immunosuppression to boost parasite development and worm egg output has not been investigated. To determine the most efficient way of propagating A. galli in young chickens an experiment with a 2 × 3 × 4 × 2 factorial design involving age of chicken at infection (day-old or 14 days old), immunosuppression (dexamethasone (DEX), cyclophosphamide (CY) or sham), infective egg dose (0, 100, 300 or 900 embryonated eggs/bird) and time of worm recovery after infection (8 or 10 weeks post-infection) was conducted. The experiment used a total of 384 layer cockerel chicks. Infection was delivered orally in 3 split doses over one week and immunosuppressants were administered by intramuscular injection concurrently with the infections. Body weight, excreta egg counts, intestinal worm count and worm establishment rate were assessed. The only sign of ascaridiosis noted was mild diarrhoea at the time of slaughter in some birds with a significant- positive association with worm count. Infection caused a significant dose dependent reduction in body weight in non-immunosuppressed birds but this effect was ameliorated by immunosuppression. Age at infection had no significant effect on the studied variables although both worm and egg counts were numerically higher in the day-old infected groups. Egg dose significantly influenced the prevalence of infection, worm establishment rate, worm egg production and mean worm count. The 300 and 900 egg doses resulted in significantly higher worm count and egg production than the 100 egg dose. A significant negative correlation was observed between egg dose and worm establishment rate indicating an inverse relationship. Immunosuppression with DEX, but not CY resulted in significantly higher mean worm burden than in control chickens with excreta egg counts also considerably higher in DEX treated birds. Our results suggest that trickle infection at day-old with infective doses of 300 eggs coupled with immunosuppression with DEX would provide the most efficient way to propagate A. galli worms in vivo, as using older birds or a higher egg dose did not provide any advantage.

The Response of Layer Hen Productivity and Egg Quality to an Additional Limestone Source When Offered Diets Differing in Calcium Concentrations and the Inclusion of Phytase

Simple Summary

Dietary calcium is essential for optimal egg production and quality in laying hens, but high concentrations can impede the digestibility of other dietary components. The provision of limestone grit in addition to the main diet may help maintain overall calcium intake while allowing a reduction in dietary calcium levels. The impact of phytase, an enzyme that increases calcium availability in the gut, on the voluntary consumption of limestone grit is unknown. Here, the capacity for hens with access to a separate limestone grit source to modify Ca consumption when offered varying dietary Ca levels and phytase was evaluated. Dietary phytase reduced limestone grit consumption. Egg production was unaffected by reducing dietary calcium levels or the phytase addition. Eggshell measurements worsened in line with decreasing dietary calcium levels despite the provision of limestone grit. In summary, the provision of limestone grit resulted in comparable egg production but not eggshell quality in hens offered suboptimal levels of dietary calcium.

Abstract

Laying hens require substantial quantities of calcium (Ca) to maintain egg production. However, maintaining recommended dietary Ca through inclusion of limestone may impede nutrient digestibility, including that of other minerals. It was hypothesized that providing a separate source of dietary Ca in the form of limestone grit would preserve Ca intake of hens offered diets containing suboptimal Ca concentrations. Furthermore, the impact of dietary phytase at a “superdosing” inclusion rate on the voluntary consumption of limestone grit was evaluated. One hundred and forty-four laying hens (19 weeks of age) were assigned to one of six dietary treatments in a 3 × 2 factorial arrangement comprising three dietary Ca concentrations (40, 30, and 20 g/kg) and ±dietary phytase (3500 FYT/kg diet) on an ad libitum basis for six weeks. Limestone grit (3.4 ± 1.0 mm) was provided to all hens ad libitum. Hens offered diets containing phytase consumed significantly less limestone grit p = 0.024). Egg weight, rate of lay, and egg mass were unaffected by dietary treatment (p > 0.05). Egg shell weight % (p < 0.001), shell thickness (p < 0.001), and shell breaking strength (p < 0.01) decreased in line with dietary Ca levels. In summary, dietary superdosing with phytase reduced the consumption of a separate limestone source in individually housed, early lay ISA Brown hens. Egg shell quality variables but not egg production worsened in line with lower dietary Ca levels.

Black soldier fly larvae in broiler diets improve broiler performance and modulate the immune system

Non-conventional feed ingredients are receiving more interest in their ability to increase farming efficiency, sustainability and animal performance. The objective of this study was to determine the optimal rate of inclusion level of the full-fat black soldier fly larvae (BSFL) in broiler diets and to evaluate their impact on performance, nutrient digestibility, and the immune system (blood cells and intraepithelial lymphocytes). A total of 400 male day-old Ross 308 broilers were randomly assigned to 5 treatment groups with 8 replicates each. Five inclusion levels of full-fat BSFL were investigated across starter (0, 2.5%, 5%, 7.5% and 10%), grower and finisher diets (0, 5%, 10%, 15% and 20%). All diets were formulated based on digestible amino acid values according to the Aviagen (2016) recommendations. A polynomial regression at different degrees was performed to analyse broiler performance parameters (body weight, body weight gain, feed intake, and feed conversion ratio), nutrient digestibility, and blood cell count. Intraepithelial lymphocyte population data was analysed performing univariate linear regression. During the entire experimental period (from 2 to 42 d), BSFL inclusion levels decreased the feed conversion ratio by 10% in broilers that received 20% BSFL in their diets (P < 0.05). Lymphocytes and white blood cell count decreased linearly by 47.7% and 35.9%, respectively, with up to 20% BSFL inclusion (P < 0.001). A 4-fold decrease in CD3+ T lymphocytes and a 9.7-fold decrease of CD3+CD8+ intestinal cytotoxic T lymphocytes occurred in broilers fed 20% BSFL compared to the control group. These findings suggest that the inclusion of BSFL can improve broiler performance and potentially reduce immune response energy expenditure in birds fed 20% BSFL for 42 d.

Comparative therapeutic efficacies of oral and in-water administered levamisole, piperazine and fenbendazole against experimental Ascaridia galli infection in chickens

Evidence on the current efficacy status of anthelmintics used in the Australian poultry sector is lacking. A controlled trial was conducted to evaluate the efficacy of three commonly used anthelmintics, namely levamisole (LEV), piperazine (PIP) and fenbendazole (FBZ) plus levamisole-piperazine combination (LEV-PIP) against a field strain of A. galli recovered following flock treatment with LEV. A total of 108 A. galli infected cockerels were randomized into nine experimental groups of 12 cockerels each (eight treatments and one untreated control) with each treatment administered by two routes (oral drench or in drinking water). Chickens received label-recommended doses of LEV (28 mg/kg) and PIP (100 mg/kg) while LEV-PIP involved both compounds co-administered at their full individual dose rates. FBZ was tested at two dose rates; 10 mg/kg as a single oral drench or 5 mg/kg in drinking water over 5 days. Anthelmintic efficacies were assessed by worm count reduction (WCR%) and excreta egg count reduction (EECR%) estimated by two methods. Ten days post treatment, the untreated control birds harboured significantly higher worm counts (P < 0.0001) than those in all treatment groups irrespective of the mode drug of application. Oral drenching caused a greater reduction in worm and egg counts (P < 0.05) than medication in drinking water. Based on geometric worm counts the percentage efficacies for the oral drench were 99.1, 96.3, 97.2 and 100 % respectively for LEV, PIP, FBZ and LEV-PIP, and for administration in water 96.4, 93.7, 88.7 and 97.7 % respectively. Efficacies based on EECR% were consistent with WCR% with strong positive linear association between efficacy values. In conclusion, our results demonstrate no evidence of loss of susceptiblity of the test A. galli isolate to both LEV and PIP contrary to our hypothesis. Additional efficacy studies are needed using A. galli isolates sourced from different poultry flocks across Australia.

Global and regional prevalence of helminth infection in chickens over time: a systematic review and meta-analysis

Gastrointestinal helminth parasites are a concern for the poultry industry worldwide as they can affect the health, welfare, and production performance. A systematic review of the prevalence over time in different countries may improve our understanding of gastrointestinal helminthiasis in chickens and subsequently lead to improved poultry health. The aim of this systematic review and meta-analysis was to provide an overview of the published information regarding the epidemiology and the diagnostic approaches of chicken helminth infection. Six databases were searched for studies, and a total of 2,985 articles published between 1942 and 2019 were identified and subsequently screened for eligibility using title or abstract and full text assessment, resulting in 191 publications to be used in the study. Postmortem diagnostics (73.8%) and the flotation technique (28.8%) were commonly used to detect helminth infections with a pooled prevalence of 79.4% ranging from 4 to 100%. More than 30 helminth species in chicken populations were identified including Ascaridia galli (35.9%), Heterakis gallinarum (28.5%), Capillaria spp. (5.90%), and Raillietina spp. (19.0%) being the most prevalent. The reported prevalence of helminth infection decreased over time in developing countries while it increased in the developed world. Chicken kept in backyard and free-range systems had a markedly higher pooled prevalence of helminth infection (82.6 and 84.8%, respectively) than those housed in cage production systems (63.6%). This may indicate the need for more rigorous control and prevention measures in free-range and backyard production systems using regular deworming coupled with access to early and accurate diagnosis allowing for early intervention.

Technological Quality, Amino Acid and Fatty Acid Profile of Broiler Meat Enhanced by Dietary Inclusion of Black Soldier Fly Larvae

We evaluated the effects of full-fat black soldier fly larvae (BSFL) on broiler carcass composition, cut yield, and breast meat quality. Broilers were fed for 42 days with up to 20% dietary inclusion of BSFL (0, 5, 10, 15, and 20%). On day 42, 120 broilers were slaughtered, and images were taken using computed tomography. Breasts, drumsticks, and thighs were collected for cut yield determination. The pH, color, lipid oxidation, cooking loss, shear force, amino acid profile, and fatty acid profile of the breast meat were assessed. There was no dietary effect on carcass composition or meat quality parameters except for fatty and amino acids compositions. When 20% BSFL was included in the diet, individual fatty and amino acids, such as lauric and myristic acids, aspartic acid, glutamine, and lysine, increased by 22.0-, 5.50-, 1.08-, 1.06-, and 1.06-fold, respectively (p < 0.05). Although total polyunsaturated fatty acids decreased, eicosapentaenoic fatty acids (EPA) increased by 78% in the 20% BSFL inclusion group. In conclusion, up to 20%, dietary full-fat BSFL did not affect key meat characteristics but positively increased the levels of the health-claimable omega-3 fatty acid EPA.

Nutrition, feeding and laying hen welfare

The relationship between nutrition and welfare is usually considered to be a direct result of supplying the hen with adequate quantities of feed and water. This simple notion of freedom from hunger and thirst belies the fact that nutrients play a pivotal role in the body’s response to challenges whether they relate to ambient temperature, gastrointestinal health, pathogen exposure, metabolic disorders, or social and mental stress. In all instances, maintaining homeostasis and allowing for physiologic response is dependent on an adequate and balanced nutrient supply. It is accepted that most laying hens are fed a complete diet, formulated commercially to provide the required nutrients for optimal health, egg production and welfare. In other words, the laying hen, irrespective of her housing, does not experience hunger or thirst. However, despite adequate nutrient and water supply, certain senarios can significantly affect and alter the nutrient requirements of the hen. Furthermore, the chemical composition and also the physical form of feed can significantly contribute to prevent or treat welfare and health conditions and is, therefore, a highly relevant tool to ensure and maintain an adequate welfare status. Therefore, this review takes a broader perspective of nutritional welfare and considers the nutrition of hens managed in different production systems in relation to nutritional physiology, gut microbiota, stress, metabolic disorders and feeding management.

Managing Free-Range Laying Hens-Part B: Early Range Users Have More Pathology Findings at the End of Lay but Have a Significantly Higher Chance of Survival-An Indicative Study

Simple Summary

Free-range facilities may present a biosecurity risk in some situations, but range use has also been associated with better hen welfare. We investigated the association between early-life range use (when hens were 18–21 weeks of age) and hen survival during the entire housing period as well as various health and welfare parameters at 74 weeks of age. Hens that preferred to use the range at early life were three times more likely to survive. Early range users were also 1.6 times more likely to become infected with gastrointestinal nematodes and showed significantly more frequent signs indicating spotty liver disease. Hens that preferred to stay in the shed during early life had a higher prevalence of Fatty Liver Syndrome and significantly less feather cover. In conclusion, hens that do not range during early life may benefit from additional management strategies to increase their likelihood of survival. Further investigations under controlled environmental conditions are warranted to quantify further the observed effects.

Abstract

While free-range laying hens frequently experience health and welfare challenges, the contribution of range use towards these risks are largely unknown. The aim of this pilot study was to investigate the survival, health and welfare of commercial free-range laying hens and explore the association with early range use. Range use of 9375 Lohmann Brown hens housed within five flocks was assessed during 18–21 weeks of age and individual hens were classified as “rangers” (frequent range users), “roamers” (intermittent range users), and “stayers” (rare/no range users) were then subject to necropsy at 74 weeks of age. Rangers and roamers were three times and 2.4 times more likely to survive than stayers, respectively (p = 0.001). Overall, rangers had significantly better feather cover and more lesions associated with spotty liver diseases compared to roamers and stayers (p = 0.001). Similarly, rangers and roamers had a higher prevalence of A. galli infection and less frequent signs of fatty liver syndrome compared to stayers. Rangers had a higher proportion of hens with full ovary follicle production compared to stayers and roamers (p = 0.035). This information is highly relevant to consider the targeted support of different flock subpopulations to improve hen health and welfare, directly affecting farm profitability. Further research on other farms is warranted to investigate the transferability of the observed results.

Frequent Visits to an Outdoor Range and Lower Areas of an Aviary System Is Related to Curiosity in Commercial Free-Range Laying Hens

Individual hen preferences to spend time at particular locations within a free-range aviary system and relationships with temperament is relatively unknown. Hens (n = 769) from three commercial flocks were monitored with Radio Frequency Identification technology to determine time spent on the range, upper and lower aviary tiers, and nest boxes. Prior depopulation, novel arena (NA) and novel object (NO) tests assessed exploration and fearfulness. During early life; more time on the lower tier was associated with more lines crossed in the NA test (p < 0.05). No other evidence suggested preference during early life was related to fear or curiosity. More time on the range and lower tier were associated with heavier pre-ranging body weight and gain (p = 0.0001). Over the hens' whole life; time spent on range and lower tier was associated with approaching the NO (p < 0.01). More time spent on the upper tier was associated with less time near the NO and fewer lines crossed in NA (p < 0.01). The relationships during early and whole life use of space and some potential indicators of fearfulness were inconsistent and therefore, no strong, valid, and reliable indicators of hen fearfulness such as freezing were identified.

Managing Free-Range Laying Hens-Part A: Frequent and Non-Frequent Range Users Differ in Laying Performance but Not Egg Quality

Simple Summary

Free-range laying hens are allowed to roam around and exhibit their desired behaviours including usage of the outdoor range. Consequently, flock sub-populations of high-range users (“rangers”) and low-range users (“stayers”) appear. The subpopulation effect on egg production and egg quality has not been studied to date. Rangers were more consistent in their range use, while stayers increased their range use over time. Rangers came into lay earlier compared to the stayers but their egg production dropped during mid-lay until the end of lay when they were outperformed by the stayers. The flock sub-populations did not differ in their egg quality during the production period. These findings are of relevance to egg producers, as it allows them to manage their flock knowing that they can encourage them to range/stay in the shed without compromising egg quality, including off-grade eggs. In the future, it would be interesting to investigate if increased egg performance was triggered by the more frequent range usage.

Abstract

Little is known about the impact of ranging on laying performance and egg quality of free-range hens. The aim of this study was to characterise egg production of commercial free-range laying hen sub-populations of low-, moderate- and high-range use at an early age. A total of five flocks with 40,000 hens/flock were investigated where 1875 hens/flock were randomly selected at 16 weeks of age, monitored for their range use and subsequently grouped into “stayers” (the 20% of hens that spent the least time on the range), “roamers” (the 20% of the hens that used the range more than stayers but less than rangers) and “rangers” (the 60% of the hens that spent the most time on the range). Eggs from the individual groups were collected in 10-weekly intervals until hens were 72 weeks of age, commercially graded and tested for several quality parameters. Significant differences were noted for hen-day production. For example, at 22 weeks of age, rangers enjoyed a laying rate of 88.0% ± 1.1%, while stayers performed at 78.2% ± 1.9% but at 72 weeks of age egg production of rangers was 85.1% ± 0.9% and of stayers was 95.5% ± 0.9% (p < 0.05). Range use was of minor importance to the egg quality.

Characterising Free-Range Layer Flocks Using Unsupervised Cluster Analysis

This study aimed to identify sub-populations of free-range laying hens and describe the pattern of their resource usage, which can affect hen performance and welfare. In three commercial flocks, 3125 Lohmann Brown hens were equipped with radio-frequency identification (RFID) transponder leg bands and placed with their flock companions, resulting in a total of 40,000 hens/flock. Hens were monitored for their use of the aviary system, including feeder lines, nest boxes, and the outdoor range. K-means and agglomerative cluster analysis, optimized with the Calinski-Harabasz Criterion, was performed and identified three clusters. Individual variation in time duration was observed in all the clusters with the highest individual differences observed on the upper feeder (140 ± 1.02%) and the range (176 ± 1.03%). Hens of cluster 1 spent the least amount time on the range and the most time on the feed chain located at the upper aviary tier (p < 0.05). We conclude that an uneven load on the resources, as well as consistent and inconsistent movement patterns, occur in the hen house. Further analysis of the data sets using classification models based on support vector machines, artificial neural networks, and decision trees are warranted to investigate the contribution of these and other parameters on hen performance.

The association between range usage and tibial quality in commercial free-range laying hens

1. Bone tissue adapts continuously to metabolic calcium demands, as well as to external forces due to physical weight loading subject to hen movement. Limited calcium metabolism and, subsequently, its availability from the medullary bone, is a major factor contributing to reduced eggshell quality in hens in the late laying period (>60 weeks of age). 2. Increasing physical activity and biomechanical loading during hen rearing has been demonstrated to increase skeletal strength, enhancing bone mass as well as endocortical and periosteal bone metabolism. Presently, the consequences of range use during lay on bone quality characteristics in laying hens remain unknown. 3.The aims of this study were to characterise tibiotarsal bone indices and evaluate the impact of range access during lay on tibia bone quality in commercial free-range laying hens. 4. This exploratory study described and analysed the volumetric measurements, morphological mechanical and trabeculae indices of the tibiotarsal bone of 48 Lohmann Brown laying hens at 74 weeks of age. All bone parameters were obtained using micro-computed tomography and correlated with individual hen range use. 5. Range usage throughout lay was not associated with tibial trabecular architecture (bone volume and fraction, trabecular thickness, trabecular connectivity density and structural model index), or any other morphological characteristics (breaking strength, diaphyseal diameter, bone weight and bone mineral density) of the tibia (P > 0.05) when hens were 74 weeks of age. 6. The results demonstrated a large variation in individual bone characteristics and suggested that range usage was not associated with bone quality in commercial free-range laying hens used in this study. In conclusion, the bone health of free-range commercial laying hens may be positively impacted by other features, such as hen genetics, feed, the quality of pullet rearing, perch availability or other shed equipment, and the benefits of these variables exceed the benefit of range use.

Various bone parameters are positively correlated with hen body weight while range access has no beneficial effect on tibia health of free-range layers

The aim of this study was to determine if body weight or range use has a significant impact on bone health in commercial free-range laying hens, and to correlate tibia bone quality parameters with individual range usage and body weight. A total of 30 Lohmann Brown hens at 74 wk of age were selected from a commercial free-range farm and were either classified as heavy (mean ± SEM body weight 2.11 ± 0.034 kg, n = 14) or light (1.68 ± 0.022 kg, n = 16) body weight, and also classified as rangers (accessed the range for 86.7% of available days, n = 16) or stayers (accessed the range for 5.00% of available days, n = 14). The left tibiae of all individuals were analyzed for morphological parameters using computed tomography, evaluated for bone breaking strength, and ashed to determine mineral composition. Keel bone scoring was performed based on observation. Data were analyzed using a 2 × 2 factorial ANOVA, and regression analysis was performed. There was no measurable effect of range usage on any of the tibia parameters investigated. The body weight was significantly correlated with tibia breaking strength (r = 0.59), tibia weight (r = 0.56), tibia length (r = 0.64), diaphyseal diameter (r = 0.61), and total tibia volume (r = 0.67). In conclusion, range access had no beneficial effect on bone health. The impact of internal hen house furnishing and movement on bone health needs further investigation.

The impacts of Ascaridia galli on performance, health, and immune responses of laying hens: new insights into an old problem

Gastrointestinal nematodes are re-emerging in countries where the popularity of free-range poultry production systems is increasing. Amongst all gastrointestinal nematodes, Ascaridia galli is of significant concern due to the parasite's direct life cycle and ability to survive extreme environmental conditions. In laying hens, A. galli parasites have been associated with reduced health, welfare, immunity, and egg production. Direct losses are caused by obstruction and damage of the intestinal tract in hens when high worm burdens are present. These result in reduction in egg production and body weight of infected laying hens, consequently leading to significant economic losses for farmers. Furthermore, heavy infections with A. galli may lead to increased mortality within the flock. Indirect losses are due to suppression of immune system function which can increase susceptibility to secondary infections. Infection with A. galli can also alter nutrient utilization and absorption. Levels of anti- A. galli serum and egg yolk antibodies increase following A. galli infection. Elevated antibodies can be used as an indicator of current or previous infections and therefore can be used as a diagnostic tool. The impact of A. galli on hen health and welfare manifests through the depletion of liver lipid reserves and increased use of energy reserves to mount immune responses against the parasite. This review highlights the variable effects of A. galli infection on the performance, health, egg quality, and emphasizes especially on immune responses of free-range laying hens as well as it evaluates various potential detection methods and preventive and control measures of this parasitic disease.

Effect of pecking stones and age on feather cover, hen mortality, and performance in free-range laying hens

Severe feather pecking is frequently associated with impaired egg production, poor hen welfare, and increased mortality. The aim of this study was to investigate the potential of pecking stones to ameliorate the incidence of feather pecking. A total of 18 flocks of Hy-Line Brown laying hens were randomly assigned to control (n = 9 no pecking stone access) or treatment (n = 9 pecking stone access) flocks and housed in commercial fixed sheds (farm A, n = 10) or commercial mobile sheds (farm B, n = 8) differing in various housing conditions. Beak length, feather score, egg production, and mortality were evaluated at 16 wk of age and every 10 wk until at least 46 wk of age. On farm A, hens with access to pecking stones had significantly lower mortality than hens without pecking stone access (P = 0.001). A significant interaction between pecking stone and age was observed on feather scores of wings of hens housed in farm A. Hens of the pecking stone group in farm A had higher wing feather score (indicating better feather condition) at the age of 56 and 66 wk than hens with no access to pecking stones (pecking stone × age, P = 0.002). The age of the hens was significantly associated with lower overall feather scores (poorer feather condition), reduced egg production, and higher mortality (P < 0.05). Although pecking stones reduced some feather loss and mortality, this effect was only present on one farm and therefore may be related to farm management. Especially the impact of pecking stones on mortality was inconclusive as the cumulative mortality in farm B was nearly twice as high compared with that in control flocks. Further investigations are warranted including the effects of pecking stone provision at an early age such as during rearing (0–17 wk of age).

A comparison of eggshell mineral composition between cage and free-range eggs via inductively coupled plasma-optical emission spectrometry

Context In Australia and many other countries, free-range eggs can be sold at significantly higher prices than cage eggs. Mislabelling cage eggs as free-range eggs and vice versa has been documented, and has a significant impact on consumer trust and egg consumption. The development of methods to identify eggs produced from different production systems is necessary to satisfy consumer demand. Aims The objective of this study was to determine whether eggshell mineral composition could be used as a way to differentiate eggs originating from each production system. Our hypothesis was that birds with access to soil would have higher levels of trace minerals in shells. Methods Eggs were randomly collected from six commercial caged and six commercial free-range flocks in Australia. Twelve eggshell samples from each flock were analysed for mineral composition (Ca, P, Mg, Na, Al, B, Cu, Mn, Fe, K, S and Zn) by using inductively coupled plasma-optical emission spectrometry. Key results The results showed that free-range eggshells contained significantly higher contents of macro-minerals (P, Mg and Na) but lower contents of micro-minerals (Cu, Fe, K, S and Mn) than the cage eggshells (P &lt; 0.05). For all minerals measured, a high variability was noted within and between production systems. Conclusions Analysis of eggshell mineral composition may not be effective for determining the origin of eggs. Implications Systematic studies of the bird’s environment, including analysis of mineral composition in diets, pastures, soil and drinking water are required for comprehensive evaluation of the influences of production systems of laying hens on mineral composition of eggs and eggshells.

Flock use of the range is associated with the use of different components of a multi-tier aviary system in commercial free-range laying hens

1. The objective of this study was to investigate the association of using a multi-tier aviary system and access to range on flock uniformity in free-range laying hens, and to determine whether the extent of range use or flock uniformity can be predicted from the use of different levels of the aviary system.2. A total of 13,716 Lohmann Brown hens from five commercial free-range flocks housed in identical houses on the same farm were individually weighed at 16 weeks of age and allocated to five replicate areas within each house. Hen movement in the multi-tier aviary system and on the range was individually monitored using radio frequency identification (RFID). All hens had access to the range from 18 to 22 weeks of age and were exposed to the same management conditions.3. Whilst only one flock significantly changed its flock uniformity with time, they differed from each other in uniformity and body weight (P = 0.001).4. Hens spent most of their available time on the lower aviary tier (7.29 ± 0.029 h/hen/day) and on the upper aviary tier (4.29 ± 0.024 h/hen/day) while the least amount of time was spent on the range and in the nest boxes (0.93 ± 0.005 h/hen/day and 1.48 ± 0.007 h, respectively, P = 0.001).5. Range use was negatively correlated (r = -0.30) to the time spent on the upper aviary tier and positively correlated (r = 0.46) to the time spent on the lower aviary tier (P = 0.001). Bivariate analysis revealed that range and upper aviary resp. lower aviary tier usage had a significant curvilinear association.6. In conclusion, the study showed that range use was associated to the time hens spent on the different tiers of the aviary system. Flock uniformity varied between flocks but was not associated with either range and aviary system usage.

Determination of gastrointestinal passage rate using three different markers in laying hens

The titanium dioxide (TiO₂ ) marker technique is currently widely practiced as a method to evaluate gastrointestinal (GI) passage rate in poultry. However, this method requires sacrificing the animal to obtain digesta samples, is labour-intensive and eliminates the possibility of follow-up studies with the same individual. The aim of this study was to evaluate whether the radiographic methods barium-impregnated polyethylene spheres (BIPS) and barium sulphate (BaSO₄ ) suspension are in agreement with the TiO₂ technique and can be used as an alternative method for GI passage rate determination in laying hens. Whole-body radiographs were taken at different time points. Hens of group 3 (n = 55) were orally inoculated with 5 g of feed mixed with 0.15 g TiO₂ , 5 hens per time point sacrificed, and whole gastrointestinal organs (crop, proventriculus, gizzard, small intestine and large intestine) were collected and analysed for TiO₂ content. The average marker passage rate of hens administered BaSO₄ was significantly faster than those administered BIPS (gizzard: 15.2 hr vs. 43.2 hr; small intestine: 15.2 hr vs. 38.4 hr, respectively). A greater percentage of BIPS remained in the crop at 0, 0.5, 2, 3 and 8 hr post-inoculation (p.i.) and in the gizzard at 2, 24, 36 and 48 hr p.i. (all p < 0.05) compared to TiO₂ . In conclusion, the evaluation of the GI transit time is feasible using BIPS, TiO₂ and BaSO₄ . The evaluation of the GI transit time using BIPS and BaSO₄ needs further investigation.

Feed particle selection and nutrient intake altered by pecking stone consumption and beak length in free-range laying hens

The present study investigated the effects of pecking stones on feeding behaviour of hens from 16 to 46 weeks of age. Eighteen flocks of Hy-Line Brown hens were housed in 2 commercial free-range housing systems. Farm A housed 10 flocks of beak trimmed (infrared beak treatment) hens in fixed sheds. Farm B housed 8 flocks of hens with intact beaks in mobile sheds. On each farm, flocks were equally assigned to control groups (no access to pecking stones) and treatment groups (access to pecking stones). Data were evaluated every 10 weeks. At each time point, 10 hens per flock were housed in individual pens, and each hen was provided with 250 g of mash diet and ad libitum water for 24 h. After 24 h, feed samples were collected and used to determine 24-h feed intake. Nutrient and particle selection was measured by subtracting nutrients and particles present in the leftover feed from the vaules obtained in the offered feed and expressed the change (Δ). In addition, pecking stone consumption was recorded for each flock. Data were analysed separately for each farm using fixed effects of pecking stone availability and hen age. Spearman's rho correlation coefficients and linear regression models were constructed to evaluate the relationship of beak length and pecking stone usage, discrete mean particle size (dMEAN) consumption (Δ dMEAN), and Δ nutrient intake. Hens with access to pecking stones consumed significantly lower quantities of large feed particles (>2.8 mm) on farm A (P = 0.029) and selected significantly more fine particles, on farm B (P = 0.013). Overall, positive relationships (P = 0.001) between beak length and pecking stone consumption, Δ dMEAN, and Δ phosphorus consumption were observed. In conclusion, pecking stone consumption resulted in reduced selection and consumption of feed particles in hens housed on both farms. Further research is warranted to investigate the effect of pecking stones on sensory innervation of the beak.

Enzymes and/or combination of organic acid and essential oils supplementation in pasture-fed free-range laying hens increased the digestibility of nutrients and non-starch polysaccharides

Pasture intake can be a major challenge for free-ranging hens. This study was conducted to examine pasture digestion and to manage its negative effects. A total of 300 ISA Brown laying hens were used to investigate the effect of time on range (T) in short-term (6 wk) and long-term (12 wk) of 2 range types (R) (gravel vs. pasture) and dietary supplements (F) (T1 = xylanase; T2 = xylanase/beta-glucanase/pectinase/protease; T3 = xylanase/benzoic acid/essential oils) on crude protein, crude fiber, acid detergent fiber, neutral detergent fiber, non-starch polysaccharides (NSP), calcium and phosphorus digestibility, pH of the crop, and ileum digesta viscosity and morphology. Hens exposed to the range for 12 wk had lower (P < 0.05) digestibility of crude protein, insoluble rhamnose, ribose, and lower ileal pH compared to hens that ranged for 6 wk. Hens ranging on pasture had lower digestibility (P < 0.05) of crude protein, acid detergent fiber, neutral detergent fiber, insoluble arabinose, and insoluble xylose, but higher digestibility (P < 0.05) of insoluble mannose and glucose compared to hens that ranged on gravel. Hens fed T2 and T3 had higher digestibility (P < 0.05) of CP, acid detergent fiber, and neutral detergent fiber compared to hens fed T1. Hens fed T2 had higher digestibility (P < 0.05) of free oligosaccharide arabinose and xylose than those fed T1 or T3 diets. A significant interaction between T × R was detected for crude fiber digestibility and villus height. Digestibility of crude fiber was reduced and villus height was increased in hens ranged on pasture for 12 wk compared to 6 wk. An interaction between R × F was observed on phosphorus and soluble NSP digestibility (P < 0.05). Hens fed T2 and T3 diets had lower digestibility of phosphorus and NSP on gravel than on pasture. In conclusion, pasture consumption impaired the digestibility of nutrients. Supplementing free-range diets with a multi-enzyme or xylanase/benzoic acid/essential oil product reduced these negative effects and increased the ileal nutrient digestibility.

Insect protein in animal nutrition

Global meat consumption per capita is expected to increase ~40% from 2019 to 2050. Over 30% of the total cropland worldwide is currently being used to produce either livestock and poultry feed or silage to meet the demand. One solution to reduce cropland use for animal feed is to increase the production of alternative protein sources. The primary protein sources for animal nutrition, including soybeans, peas and fish meal, are of increasing demand and are subsequently becoming more expensive, making their long-term use unsustainable. Insects such as the black soldier fly larvae (Hermetia illucens), crickets (Gryllus testaceus Walker) or mealworms (Tenebrio molitor) offer a viable addition to the feed sources and can provide valuable, high-quality energy, protein and fat to an animal’s diet. Here, we review the environmental benefits of insect feedstuff, current research findings related to the use of insects for animal nutrition, and outline additional products that can generate benefits to insect producers.

Analysis of antibody levels in egg yolk for detection of exposure to Ascaridia galli parasites in commercial laying hens

Ascaridia galli is one of the most abundant nematode parasites in poultry. A. galli infections can significantly impact the profitability of egg farms and have negative implications for bird health and welfare. The main objectives of this study were to determine whether A. galli specific antibodies in egg yolks can be used to detect prior or current exposure to A. galli in laying hens, and to distinguish between eggs obtained from caged and free-range hens. Twenty-two laying hen flocks from different production systems (10 free-range, 2 barn-housed, and 9 caged flocks) were enrolled in the study. An in-house enzyme-linked immunosorbent assay was used to analyze levels of A. galli specific antibodies in yolk. The numbers of A. galli eggs in hen excreta were also determined in a subset of farms. Free-range flocks had higher and also more variable levels of anti-A. galli antibodies in the egg yolk compared to those of the cage flocks (0.50 ± 0.39 vs. 0.16 ± 0.13 OD units) (P < 0.001). Results also confirmed that excreta from free-range and barn-housed flocks contained higher numbers of A. galli eggs than did excreta from caged flocks in which no A. galli eggs were detected. In conclusion, analysis of anti-A. galli antibodies in the egg yolk can be used to detect worm exposure in commercial layer flocks. However, the method used in this study cannot be used in isolation to distinguish between eggs from cage and free-range production systems as anti-A galli antibodies were detected in egg yolk samples from all production systems, and the range of antibody levels overlapped between production systems.

Free-range laying hens: using technology to show the dynamics and impact of hen movement

Free-range laying hens are provided with the opportunity to access various structural areas, including open floor space, feed areas, water lines, next boxes, perches, aviary tiers, winter gardens and ranges. Different individual location preferences can lead to the development of hen subpopulations that are characterised by various health, welfare and performance parameters. Understanding the complexity of hen movement and hen interactions within their environment provides an opportunity to limit the disadvantages that are associated with housing in loose husbandry systems and aids in decision-making. Monitoring hen movement using modern technologies such as radio-frequency identification (RFID), optical flow patterns, image analysis and three-dimensional (3D) cameras allows the accumulation of big data for data mining, clustering and machine learning. Integrating individual-based management systems into modern flock management will not only help improve the care of under-performing hens, but also ensure that elite hens are able to use their full genetic potential, allowing an ethical, sustainable and welfare friendly egg production. This review highlights the dynamics and impact of hen movement in free-range systems, reviews existing knowledge relevant for feeding hens in non-cage systems, and outlines recent technological advances and strategies to improve the management of free-range laying hens.

Impact of on-range choice feeding with black soldier fly larvae (Hermetia illucens) on flock performance, egg quality, and range use of free-range laying hens

Semi-intensive free-range farm systems are common in Australia, and these systems frequently practise on-range feeding. The objective of this study was to investigate the benefit of on-range choice feeding on flock performance, egg quality, and range use of free-range laying hens using black soldier fly larvae (Hermetia illucens, BSF). A total of 160 mature ISA brown laying hens, previously determined to range daily, were allocated to a control group (control) or a treatment group (BSF) with various replicates depending on the parameter investigated. All hens were fed ad libitum indoors with a wheat-soy based diet formulated according to breed requirements. Black soldier fly hens were offered dried BSF larvae ad libitum on the range. Body weight, feed intake, BSF intake, egg production, feed conversion ratio, internal and external egg quality parameters, and individual range use using radio-frequency identification (RFID) technology was evaluated. Black soldier fly hens consumed on average 15 ± 1.7 g BSF larvae/hen per day. There were no differences between BSF and control hens for any of the performance parameters obtained (P > 0.05). Egg weight, shell weight, and shell thickness of eggs from BSF hens were significantly lower (P = 0.003, P = 0.001, and P = 0.004, respectively) than those of eggs from control hens. Egg yolk colour was significantly paler in eggs from BSF hens (P < 0.001). No significant ranging differences between the BSF and control hens were observed (P > 0.05) except for BSF hens showing longer total maximum time for a single visit to the range (P = 0.011). In conclusion, the average intake of BSF larvae indicated a good level of acceptance. Feed formulation should be adjusted for the intake of the choice fed source. The impact of choice-feeding on range use was minor.

Pasture, multi-enzymes, benzoic acid and essential oils positively influence performance, intestinal organ weight and egg quality in free-range laying hens

1. The objective of this study was to investigate the effect of range type, multi-enzyme applications, and a combination of benzoic acid (BA) and essential oils (EO) on the productive performance, organ weight and egg quality of free-range laying hens. 2. Three hundred laying hens were evaluated for the short-term (6 weeks) and long-term (12 weeks) effects of range type (G = no pasture, P = pasture) and feed additives (T1 = control; T2 = betaglucanase/pectinase/protease; T3 = BA/EO). Body weight, feed intake (FI), feed conversion ratio (FCR), egg production (EP), digestive organ weight, and egg quality (EQ) were evaluated. Data were analysed using SPSS 2.2 in a 2×2×3 factorial arrangement. 3. Hens that ranged on pasture were significantly heavier (2043 g vs. 1996 g; p < 0.001), laid heavier eggs (61.9 g vs. 60.3 g; p < 0.001) and produced darker yolk colour (4.3 vs. 7.0; p < 0.001) compared to hens ranged on gravel. Hens fed T2 were significantly heavier (2050 g) compared to hens fed T1 (2005 g) or T3 (2008 g). Organ weights (gizzard, liver and pancreas) were significantly heavier in hens ranged on pasture (16.8 g/kg BW, 22.3 g/kg BW and 1.89 g/kg BW, respectively) compared to hens ranged on gravel (14.2 g/kg BW, 21.7 g/kg BW and 1.83 g/kg BW, respectively). Over time, body weight (1970-2070 g; p < 0.001) and egg weight (59.5-62.8 g; p < 0.001) increased, FI (123-120 g; p = 0.024) was reduced and FCR (2.36-2.10; p = 0.002) improved 4. In conclusion, hens housed on pasture and fed multi-enzyme supplemented diets had significantly heavier body weight and produced heavier eggs with darker yolk colour. Pasture intake and enzyme supplementation increased digestive organ weight significantly.

Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare

Baseline information on demographics and practices on semi-intensive free-range egg farms with an outdoor stocking density of ≤1500 hens/hectare in Australia is presented. Free-range egg production is changing the structure of the egg industry in Australia and a broad variety and tiers of free-range systems have emerged due to lack of concrete legislative standards on outdoor stocking densities in the past. Information was extracted from a pre-existing online free-range poultry survey dataset, consisting of a total of 79 questions related to nutrition, pasture management, welfare and health, animal housing, environmental impact and economics. Forty-one free-range egg farms, with an outdoor stocking density of ≤1500 hens/hectare, were identified in the dataset from all major Australian states. Two types of semi-intensive free-range housing systems were documented: mobile (modified caravan/trailer) housing (56%), and fixed sheds (44%). Seventy-two percent of respondents reported >75% of the hens in the flock used the outdoor range. All respondents reported ingestion of range components by hens in the form of vegetation, insects, stones and grit. Up to 10% mortality was reported by 40% respondents with predation (34%), cannibalism (29%), heat stress (24%) and grass impaction (19.5%) as major causes. Biosecurity on farms was sub-optimal with 8 of the 10 actions implemented by <50% respondents. Customer demand, consumer sentiment and welfare were the major factors for farmers moving into free-range egg production. This study resulted in identification of current practices and key challenges on semi-intensive free-range egg farms. Applied research and communication of results to farmers is highly recommended to ensure optimum health and welfare of free-range laying hens and sustained egg production.

Immune responses following experimental infection with Ascaridia galli and necrotic enteritis in broiler chickens

Broilers commonly suffer from necrotic enteritis (NE). Other gastrointestinal infectious diseases affect poultry, including nematode infections which are considered a re-emerging disease in barn and free-range systems. The aim of this study was to characterize the immune response of broilers after artificial infection with NE and contrast these with responses to the nematode Ascaridia galli and determine whether immune parameters measured during the course of infection can be used to distinguish infected from uninfected birds. A total of 96 one-day-old male Ross 308 broiler chickens were used in this study. At 10 days of age, broilers were randomly assigned to one of the following treatment groups: control birds (n = 32), A. galli infected birds (n = 32), or NE infected birds (n = 32) and inoculated with the appropriate infective agents. The immune response of birds was monitored through evaluation of haematology parameters, acute phase protein production, and intraepithelial intestinal lymphocyte population changes at 11, 16, 20, and 32 days of age. T-helper cells (CD4⁺CD8^-) increased significantly over time, and were significantly higher in A. galli and NE compared to day 10 controls. In conclusion, α-1 glycoprotein levels can distinguish birds with NE from other birds, including those infected with A. galli; also T-helper cell numbers can distinguish both NE and A. galli from uninfected birds and thirdly, 10 days post infection is the best time point to evaluate the bird's immune response for A. galli infections.

Effect of feed grinding methods with and without expansion on prececal and total tract mineral digestibility as well as on interior and exterior egg quality in laying hens

The grinding of cereals by various milling methods as well as thermal treatment of feed may influence mineral digestibility and egg quality. The present study investigated the effect of feed produced by disc mill (D) and wedge-shaped disc mill (WSD), as mash (M) or expandate (E) on apparent ileal absorption (AIA) and apparent total digestibility (ATD) of calcium, phosphorus, magnesium, zinc, manganese, copper and iron, as well as on egg quality in laying hens. A total of 192 hens (Lohmann Brown) aged 19 wk, were assigned using a randomized design with a 2 × 2 factorial arrangement. Four experimental diets were offered ad libitum. Eggs were analyzed for weight, shape index, area, shell weight per unit surface area, yolk color, air cell, blood spot, Haugh unit, albumen and yolk measures (index, weight, height, width and length), shell measures (surface area, stability, density, thickness and membrane weight), as well as percent contents of albumen, yolk, shell, and shell membrane. The ATD for phosphorus, manganese, and copper was higher in WSD compared with D treatment (P = 0.028, P = 0.028 and P = 0.016, respectively). The interaction between milling methods and thermal treatment influenced ATD of copper (P = 0.033), which was higher in WSD+M group (41.0 ± 20.2) compared with D+E group (-3.21 ± 25.1), whereas no differences were observed for D+M (1.90 ± 37.8) and WSD+E (8.02 ± 36.2) groups. Egg stability tended to be higher in E compared with M treatment (P = 0.055). Albumen weight, percentage albumen weight, and albumen: yolk were higher and percentage yolk weight was lower in D compared with WSD treatment (P = 0.043, P = 0.027, P = 0.024, and P = 0.041, respectively). Number of blood spots was higher in E than M treatment (P = 0.053). In conclusion, use of a wedge-shaped disc mill resulted in higher ATD for phosphorus, manganese, and copper than use of a disc mill; however, digestibility for majority of minerals as well as egg quality parameters was comparable. Therefore, feed produced by either disc mill or wedge-shaped disc mill as mash or expandate may be used for laying hens without negative effects on egg quality.

Implication of milling methods, thermal treatment, and particle size of feed in layers on mineral digestibility and retention of minerals in egg contents

Feed production with different milling methods, thermal treatment, and particle size may influence mineral digestibility and retention in eggs. The present study investigated the impact of roller (R) and hammer (H) mills, mash (M) and expandate (E) with fine (F) and coarse (C) particle sizes, on apparent ileal absorption (AIA) and apparent total digestibility (ATD) and retention of calcium, phosphorus, magnesium, zinc, manganese, copper and iron in yolk, albumen, and shell. A total of 384 hens (Lohmann Brown), 19 weeks old, were assigned using a randomized design with a 2×2×2 factorial arrangement. Eight experimental diets were offered ad libitum during the whole experimental period and one week before for diet adaption. The AIA of magnesium, zinc, copper, and iron was higher in treatment R in comparison with treatment H (P<0.01, P≤0.03, P<0.01 and P<0.01, respectively). The AIA of magnesium was higher in treatment M than treatment E (P<0.01). The AIA of magnesium was higher in treatment C in comparison with treatment F (P≤0.05) due to particle size. The ATD of copper and iron was higher in treatment R than treatment H (P<0.01 and P≤0.03, respectively). The ATD was higher for phosphorus and lower for iron in treatment F than treatment C (P≤0.05 and P≤0.02. respectively). The copper concentration in yolk and albumen was higher in treatment C than treatment F (P<0.01 and P≤0.03, respectively). Besides a few overall interactions, the AIA and ATD of copper and manganese were lower in H+M group than R+M group (P≤0.05). The ATD of iron was higher in the M+C group compared to the M+F group (P<0.01), whereas the albumen zinc concentration was higher in the E+C group than E+F group (P < 0.01). In conclusion, the feed produced by hammer mill had negative effects on AIA and ATD for trace elements in particular, but mineral concentrations in egg contents were mostly comparable for all treatments. Therefore, milling methods, thermal treatment, and particle sizes used in the present study can be used for layer feed formulation without negatively affecting egg quality.

Effects of grinding method, particle size, and physical form of the diet on gastrointestinal morphology and jejunal glucose transport in laying hens

Several studies illustrated that the structure of feed, i.e., the particle size, particle-size distribution, and the physical form of the diet, affects the avian gastrointestinal function and health leading to changes in productive performance. However, investigations concerning the effects of feeding differently processed diets on laying hens are limited and primarily concentrated on bird performance. The current study examines the effect of feed processing on the gastrointestinal morphology and on the jejunal glucose transport of laying hens. In 8 replicates, a total of 384 hens (Lohmann Brown) aged 20 wk were randomly allocated to 8 different groups and fed over a period of 21 d in a 3-factorial design. Diets differed in 1) grinding method, either hammer or roller mill; 2) physical form, either mash or expandate; and 3) particle size, either coarsely or finely ground. During the experimental trial, the laying performance of each feeding group was recorded daily and the feed intake and BW determined weekly. After slaughtering, the weights of the pancreas, proventriculus, gizzard, and small intestine were measured. Villus lengths and crypt depths of the duodenum, jejunum, and ileum were determined. The jejunal electrogenic glucose transport was studied in Ussing chambers. Hens that received mash instead of expandate had higher proventriculus (P = 0.011), gizzard (P < 0.001), and pancreas (P = 0.019) weights, whereas the feeding of coarsely instead of finely ground diets led to higher gizzard weights (P < 0.001). Mash-fed hens showed longer duodenal (P < 0.001) and shorter ileal villi (P = 0.047) and increased duodenal villus height-to-crypt depth ratios (P < 0.001) than those given the expandate. Mash-fed hens had higher glucose transport rates than expandate-fed hens (P < 0.001). In conclusion, the feeding of coarsely ground as well as mash diets had stimulating effects on the development of the gastrointestinal organs. Moreover, the feeding of mash influenced the intestinal microstructure of the epithelium that was accompanied by higher glucose transport capacities.

Evaluation of endoscopically obtained duodenal biopsy samples from cats and dogs in an adapter-modified Ussing chamber

This study was conducted to evaluate an adapter-modified Ussing chamber for assessment of transport physiology in endoscopically obtained duodenal biopsies from healthy cats and dogs, as well as dogs with chronic enteropathies. 17 duodenal biopsies from five cats and 51 duodenal biopsies from 13 dogs were obtained. Samples were transferred into an adapter-modified Ussing chamber and sequentially exposed to various absorbagogues and secretagogues. Overall, 78.6% of duodenal samples obtained from cats responded to at least one compound. In duodenal biopsies obtained from dogs, the rate of overall response ranged from 87.5% (healthy individuals; n = 8), to 63.6% (animals exhibiting clinical signs of gastrointestinal disease and histopathological unremarkable duodenum; n = 15), and 32.1% (animals exhibiting clinical signs of gastrointestinal diseases and moderate to severe histopathological lesions; n = 28). Detailed information regarding the magnitude and duration of the response are provided. The adapter-modified Ussing chamber enables investigation of the absorptive and secretory capacity of endoscopically obtained duodenal biopsies from cats and dogs and has the potential to become a valuable research tool. The response of samples was correlated with histopathological findings.

Feasibility of endoscopic retrograde cholangiopancreatography in healthy cats

Cats are predisposed to diseases of the biliary tract and the exocrine pancreas and these can be challenging to diagnose. In humans and dogs > 10 kg, endoscopic retrograde cholangiopancreatography (ERCP) has been successfully used to diagnose some of these disorders. The purpose of our study was to determine whether ERCP would also be feasible in cats using a pediatric duodenoscope. Four purpose-bred, clinically healthy, castrated domestic shorthair cats participated in two studies. Study 1 compared standard white light endoscopy with chromoendoscopy for localizing the major duodenal papilla. In Study 2 ERCP was performed. Repeated clinical examinations and measurements of serum feline pancreatic lipase immunoreactivity (fPLI) were performed before and up to 18 hours after interventions on all cats. Chromoendoscopy was subjectively judged to be superior for localizing the major papilla. Insertion of the ERCP catheter was best accomplished when cats were in dorsal recumbency. Complete ERCP was successful in two cats. In the other cats, either retrograde cholangiography or pancreatography was possible. Serum fPLI concentrations increased temporarily in two cats during Study 2 when measured immediately, 2, 4, and 18 h after ERCP. Peak fPLI concentrations were detected either immediately after ERCP or 2 h later. No clinical signs of complications were observed within 18 h after the procedures. Findings indicated that ERCP is technically demanding but feasible in healthy cats. Future studies need to determine whether the temporary increases in serum fPLI concentrations are clinically important and to investigate the utility of ERCP in feline patients.

Adapter-modified Ussing chamber enables evaluation of endoscopically-obtained colonic biopsy samples from cats and dogs

Adapter-modified Ussing chambers have been used for assessment of endoscopically obtained intestinal biopsies in humans. The aim of this study was to evaluate the feasibility of an adapter-modified Ussing chamber for assessment of intestinal transport physiology in endoscopically-obtained colonic biopsies from cats and dogs. Fifteen colonic biopsies from four cats and 13 colonic biopsies from four dogs were transferred into a modified Ussing chamber and sequentially exposed to several compounds. Baseline mean±SD conductance was measured. Changes of short circuit current (ΔIsc) were observed after exposure to glucose (number of feline biopsies that responded=0/number of canine biopsies that responded=4), phloridzin (n=0/n=7), histamine (n=5/n=12), serotonin (n=7/n=12), prostaglandin (n=5/n=7), forskolin (n=7/n=7), and ouabain (n=9/n=7). The adapter-modified Ussing chamber studied here enables investigation of transport physiology of endoscopically-obtained colonic biopsies from companion animals. However, we observed a large variability of results, suggesting that clinical use of this method is limited.

Development and analytical validation of a radioimmunoassay for the measurement of alpha1-proteinase inhibitor concentrations in feces from healthy puppies and adult dogs

Canine α1-proteinase inhibitor (cα1-PI), a proteolysis-resistant protein with a molecular weight similar to albumin, has been shown to be clinically useful as a marker for gastrointestinal protein loss in dogs. A competitive, liquid-phase radioimmunoassay was developed and analytically validated. Fecal samples were collected from 101 healthy pet dogs of various breeds and ages, and fecal cα1-PI (Fcα1-PI) concentrations were compared between dogs of different age groups. A reference interval for Fcα1-PI concentration was calculated using the central 95th percentile. Analytical sensitivity of the assay was 2.2 µg Fcα1-PI/g feces. Observed-to-expected ratios for the serial dilution and spiking recovery of 9 and 6 fecal extracts ranged from 90.4 to 152.0% and from 71.3 to 112.3%, respectively. Coefficients of variation for intra- and interassay variability for 6 fecal extracts were ≤10.8% and ≤12.5%, respectively. The reference intervals for the mean and maximum Fcα1-PI from fecal samples collected on 3 consecutive days were 2.2–13.9 µg/g and 2.2–21.0 µg/g, respectively. Fcα1-PI was significantly higher in dogs <1 year of age ( P < 0.0001 for both mean and maximum Fcα1-PI for the 3 samples). The radioimmunoassay described is sensitive, linear, precise, reproducible, and accurate for clinical use, thus allowing reliable quantification of Fcα1-PI in clinical patients. Using this assay, a mean or a maximum Fcα1-PI for 3 sampling days of >13.9 µg/g or >21.0 µg/g, respectively, should be considered abnormal in dogs >1 year of age. Fecal cα1-PI concentrations in dogs <1 year of age were significantly higher and should be carefully interpreted in this age group.