Free-range Production Systems Research Articles

Cultural drivers and health-seeking behaviours that impact on the transmission of pig-associated zoonoses in Lao People's Democratic Republic.

Pig rearing is an important income source in the Lao People’s Democratic Republic (PDR), with many smallholder farmers using traditional free-range pig production systems. Despite the potentially significant health risks posed by pig production regarding pig-associated zoonoses, information on the sociocultural drivers of these zoonoses is significantly lacking. This review summarises the existing sociocultural knowledge on eight pig-associated zoonoses suspected to be endemic in Southeast Asia: brucellosis, Q fever (Coxiella burnetii), trichinellosis, hepatitis E virus, leptospirosis, Japanese encephalitis, Streptococcus suis and Taenia solium taeniasis-cysticercosis. It summarises current knowledge on these diseases grouped according to their clinical manifestations in humans to highlight the propensity for underreporting. A literature search was conducted across multiple databases for publications from 1990 to the present day related to the eight pig-associated zoonoses and the risk and impact connected with them, with Lao PDR as a case study. Many of these pig-associated zoonoses have similar presentations and are often diagnosed as clinical syndromes. Misdiagnosis and underreporting are, therefore, substantial and emphasise the need for more robust diagnostics and appropriate surveillance systems. While some reports exist in other countries in the region, information is significantly lacking in Lao PDR with existing information coming mainly from the capital, Vientiane. The disease burden imposed by these zoonoses is not only characterised by morbidity and mortality, but directly impacts on livelihoods through income reduction and production losses, and indirectly through treatment costs and lost work opportunities. Other factors crucial to understanding and controlling these diseases are the influence of ethnicity and culture on food-consumption practices, pig rearing and slaughter practices, hygiene and sanitation, health-seeking behaviours and, therefore, risk factors for disease transmission. Published information on the knowledge, attitudes and beliefs of people regarding pig zoonoses and their risk factors is also extremely limited in Lao PDR and the broader Southeast Asian region. The need for more transdisciplinary research, using a One Health approach, in order to understand the underlining social determinants of health and their impacts on health-seeking behaviours, disease transmission and, ultimately, disease reporting, cannot be more emphasized.Electronic supplementary materialThe online version of this article (doi:10.1186/2049-9957-4-11) contains supplementary material, which is available to authorized users.

Effect of Breed and Production System on Physicochemical Characteristics of Meat From Multi-Purpose Hens

Abstract The objective of the study was to determine the effect of breed (A) and free-range production system (B) on quality of meat from hens of two breeds, Greenleg Partridge (Z-11) and Rhode Island Red (R-11), which are under the biodiversity conservation programme in Poland. Subjects were 120 hens of each breed, which were assigned to two treatment groups differing in the housing system: 60 layers were kept on litter without outdoor access (C) and 60 layers were raised on litter with access to free range (FR). At 56 weeks of age, 8 hens were randomly chosen from each group, slaughtered, and subjected to slaughter analysis. It was found from the study that carcasses from 56-week-old multi-purpose hens are characterized by poor muscle development and considerable fat content. After the first year of egg production, the meat of hens was characterized by low tenderness, high water holding capacity, and a fatty acid profile that was desirable from the viewpoint of human nutrition. In the meat of hens that completed their first year of egg production, the profile of fatty acids was beneficial from the standpoint of human nutrition. The free-range production system reduced carcass fatness, enhanced carcass and meat yellowness, and increased the proportion of polyunsaturated fatty acids (both n-6 and n-3) in breast and leg muscles while causing no significant changes in the content of saturated fatty acids. The meat of the native Z-11 breed was found to contain less saturated and more unsaturated fatty acids compared to the meat of R-11 hens. There was no statistically significant effect of the production system on the sensory evaluation of cooked meat and broth.

Confined housing system increased abdominal and subcutaneous fat deposition and gene expressions of carbohydrate response element-binding protein and sterol regulatory element-binding protein 1 in chicken.

Free-range production system is increasingly being used in poultry breeding and feed production in many countries. The objective of the current experiment was to evaluate the effects of different raising systems on fat-related traits and mRNA levels of liver lipogenesis genes in Erlang Mountainous chicken. Each of 10 birds (91 day old) from caged, indoor-floor housed, and free-range housing systems was slaughtered, and fat-related traits, live body weight (BW), subcutaneous fat thickness (SFT), abdominal fat weight (AFW), abdominal fat percentage (AFP), and intramuscular fat content were determined. The mRNA levels of liver X receptor α, carbohydrate response element-binding protein (ChREBP), sterol regulatory element-binding protein-1 (SREBP1), and fatty acid synthase were detected. The caged chicken exhibited significantly higher BW, SFT, and AFW than those of free-ranged chicken (P < 0.05). All the 4 genes had a similar expression pattern, and they showed the highest level in caged chicken, while the lowest level was found in free-ranged chicken. Association analysis indicated that there were significant (P < 0.05) or highly significant (P < 0.01) positive correlations between the mRNA levels of ChREBP, SREBP1, and fat traits of SFT, AFW, and AFP. Thus, we deduced that increased fat deposition in caged chicken was probably induced by increased gene expression of ChREBP and SREBP1 in the liver.

Cross sectional epidemiological investigation on the prevalence of gastrointestinal helminths in free range chickens in Narsingdi district, Bangladesh.

Rural poultry production in Bangladesh is mainly based on the free range or backyard poultry production system. This backyard poultry plays a vital tool for poverty alleviation as well as for empowerment of poor women of this country. However, this production system has disadvantage of susceptibility to many diseases including higher burden of parasitic infection. Therefore this cross sectional epidemiological investigation was done to determine the prevalence and distribution of gastrointestinal helminths in Narsingdi district, Bangladesh. To conduct this study a total of 150 chickens from three different villages of Narsingdi district, Bangladesh (50 chickens per village) were collected by random sampling method and killed by cervical disarticulation. Thereafter, all the chickens were necropsied and gastrointestinal tracts were examined macroscopically for the presence helminth infection. In total two nematode (Ascaridia galli, Heterakis gallinarum,) and one cestode (Raillietina spp.) were identified by post mortem examination. Raillietina spp. was detected as the most prevalent helminth species (86-92%) followed by A. galli (70-86%), and H. gallinarum (70-76%) in studied villages. In some chickens petechial hemorrhage were observed in the small intestinal wall which was associated with the A. galli infection and for some birds white tiny nodules were detected in case of H. gallinarum infection. No significant difference in parasite prevalence was observed between male and female bird as well as among three studied villages (P>0.05). We observed that most of chickens were infected with more than one species of parasites. This finding suggests that the poultry production system in rural areas of Bangladesh and the environmental conditions are very favourable for the transmission and persistence of the parasite species in rural areas of Bangladesh.

High pathogenicity and low genetic evolution of avian paramyxovirus type I (Newcastle disease virus) isolated from live bird markets in Uganda.

BackgroundNewcastle disease is still a serious disease of poultry especially in backyard free-range production systems despite the availability of cross protective vaccines. Healthy-looking poultry from live bird markets have been suspected as a major source of disease spread although limited studies have been conducted to ascertain the presence of the virulent strains in the markets and to understand how they are related to outbreak strains.MethodsThis study evaluated the occurrence of Newcastle disease virus in samples collected from poultry in live bird markets across Uganda. The isolates were pathoyped using standard methods (mean death time (MDT), intracelebral pathogenicity index (ICPI), and sequencing of the fusion protein cleavage site motif) and also phylogenetically analysed after sequencing of the full fusion and hemagglutin-neuraminidase genes. The isolates were classified into genotypes and subgenotypes based on the full fusion protein gene classification system and compared with other strains in the region and world-wide.ResultsVirulent avian paramyxovirus type I (APMV-1) (Newcastle disease virus) was isolated in healthy-looking poultry in live bird markets. The viruses belonged to a new subgenotype, Vd, in genotype V, and clustered together with Tanzania and Kenya strains. They harbored low genetic diversity.ConclusionThe occurrence of virulent AMPV-1 strains in live bird markets may serve as sources of Newcastle disease outbreaks in non-commercial farms.

Genotype by environment interaction for carcass traits and intramuscular fat content in heavy Iberian pigs fattened in two different free-range systems

Genotype by environment interaction (G×E) is a potential source of reduced efficiency in genetic improvement programs in livestock. The objective of the current work consisted of checking the existence of G×E interaction in carcass traits and in intramuscular fat content (IMF) in Iberian pigs fattened in two free-range systems. Genetic component and estimated breeding values (EBV) of the percentage of hams, shoulders and loins and IMF in loin were obtained from records of 4,348 and 1,818 pigs fattened in campo (C) and montanera (M) systems, respectively. A multitrait model where the performances of each system are considered as different traits was implemented. Three selection indexes were built with different treatments about the quality trait, two of them based in the optimal trait theory. The Pearson correlation between EBV and indexes and the Spearman correlation between the rankings of progenies of 21 boars fattened in both systems were calculated. Heritability results were different in both systems (h2 range from 0.43 to 0.66 and from 0.24 to 0.33 in C and M system, respectively) and genetic correlation of same traits expressed in the two systems also pointed out to a weak G×E interaction (0.64, 0.67 and 0.66 in hams, shoulders and IMF, respectively). Pearson and Spearman correlations were always significantly different to 1. The obtained results advised to consider this G×E interaction in the analysis model of a breeding program focused on free range production system and to include IMF in the index selection assuming an optimum range for this quality trait, in order to avoid negative effects of selection for carcass performances.

Performance of free-range chickens reared in production modules enriched with shade net and perches

An experiment was carried out to evaluate the effect of environmental enrichment in a free-range chicken production system on live performance as a function of microclimate, physiological parameters, and performance parameters. Four production modules were divided into four pens with 10 birds each, totaling 60 birds. The following treatments were applied: access to a paddock (TEST), access to a paddock with perches (PER), access to a paddock with artificial shade (SHA), and access to the paddock with perches and artificial shade (PESH). The PESH production module presented the best globe temperature (Tbg,ºC) and enthalpy (h, kJ/kg), and thereby, the best thermal environmental conditions, which ensured the longest permanence time of the birds in the paddock. The SHA and PESH modules promoted the lowest respiratory rate and shank and comb temperatures. Live performance was influenced by the presence of environmental enrichment (modules SHA and PESH), with the highest live weight (LW) and weight gain (WG) and the lowest feed conversion ratio (FCR) and metabolizable energy intake (MEI). Parts yield, such as giblets, were not influenced by production modules, except for PESH, which promoted higher offal weight. In general, chickens reared in enriched production modules presented greatest performance and comfort results and were considered close to optimal rearing conditions.

Smallholder pig production: Prevalence and risk factors of ectoparasites

A cross-sectional study was carried out in the Mbeya Region, Tanzania, with the aim of describing the distribution and diversity of ectoparasites on pigs, within confinement and free-range production systems of smallholder farms. A total of 128 farms were surveyed, with 96 practising confinement and 32 practising free-range production systems. The prevalence of ectoparasites on pigs within confinement and free-range production systems was 24% and 84%, respectively. Logistic regression analyses revealed that keeping pigs in a free-range system and the presence of neighbouring pigs were risk factors for ectoparasites. Within the confinement system, contact with neighbouring pigs and the time interval (in months) since last ectoparasitic treatment were additionally identified as risk factors. The prevalence of Haematopinus suis was 20% in confined pigs and 63% among free-range pigs. Free-ranging of pigs and presence of neighbouring pigs were also identified as risk factors for the presence of lice. Three species of fleas were identified; Tunga penetrans, Echidnophaga gallinacea and Ctenocephalides canis. The prevalence of fleas was 5% and 13% within confined and free-range, respectively. Two pigs (2%) were found infested with Sarcoptes scabiei var. suis. Ticks found belonged to four genera; Amblyomma spp., Rhipicephalus spp., Haemaphysalis spp., and Boophilus spp. The prevalence of hard ticks among the free-range pigs was 50%. Ectoparasites were more prevalent in the free-range system although highly prevalent within both production systems. Keeping pigs in a free-range system and contact with neighbouring pigs were main risk factors for the presence of ectoparasites. Confinement was highly effective as a preventive tool against hard ticks.

Differences in fatty acid composition of meat between naked neck and two commercial broiler chicken breeds

Chicken meat from intensive broiler production have different quality compared with meat from native chicken breeds and chicken from a free range production system. The aim of the present study was to evaluate differences in fatty acids content of meat of Naked Neck chickens rared in free range system and two commercial broiler breeds (Cobb 308 and Hybro G+) reared in conventional production system. The trial involved 100 chickens per group. Fattening period lasted 42 days for conventional system and 84 days for free range system. Breast meat of Naked Neck chicken had statistically more 16:0 content compared with Cobb 308 (p?0.05), where in thigh meat the highest content of 16:0 was determined in Hybro G+ breed. Differences for fatty acids composition of breast meat between breeds were also established for 14:0, 17:0, 18:0, 16:1, 18:1, 18:2, 20:2, 22:1 and 22:5 fatty acid. The Naked Neck group showed the highest (p?0.05) percentage of SFA and the Cobb 308 showed the lowest in breast meat. Thigh SFA were also significantly different (p?0.05) between breeds, where Naked Neck chickens had the lowest and Hybro G+ the highest values. Breast MUFA were higher in Hybro G+ than in Naked Neck or Cobb 308 chickens, and thigh MUFA content had opposite trend and it was the lowest in Hybro G+ chicken. In conclusion, free ranged Naked Neck chickens have been shown to have significant different fatty acid composition compared with broiler chickens reared in conventional system.

Performance and meat attributes of chickens reared on deep litter and free range

This study was carried out on the performan- ce and meat sensory attributes of 150 cockerel chickens each of Harco Black and Novogen strains reared on deep litter and free range production systems. The birds were brooded for 4 weeks and thereafter allotted to the different production systems for a period of 12 weeks. Each production system was allotted 150 chicks (75 chicks per strain) with three replicates of 25 chicks. The birds on deep litter production system were fed ad libitum while each bird on free range was fed 50 % of its daily feed requirement. On the 84 th day, a total of 36 birds were randomly selected for slaughtering by neck decapitation and the sensory attributes of the meat were determined. The data generated were subjected to a two-way analysis of variance in a 2×2 factorial experimental arrangement. Novogen strain on free range consumed less feed (p<0.05) and had the best feed: gain ratio (2.72). The results showed that the production systems and strains gave similar results by factors though higher percentage mortality was recorded in birds reared on free range. Novogen strain on free range recorded the highest (p<0.05) value of 38 % in mortality while Harco Black on deep litter recorded the least value (6 %). Significant (p<0.05) differences were found in the taste and flavour of grilled cockerel meat with Novogen strain on free range having the highest values of 8.00 and 7.50, respectively. Conclusively, for better meat sensory attributes, birds should be reared on free range.

Assessment of the meat quality of Italian Podolian and Greek Katerini cattle

In order to satisfy the demands of the modern consumer for food of high quality, low in fat but rich in polyunsaturated fatty acids, farmers from the inner regions of both Italy and Greece in recent years have started to orient their activity to the rearing of autochthonous animal populations, as in the case of the bovine Podolian (Italy) and Katerini (Greece). As both of these populations (raised in two different countries, but under a similar free-range production system) were derived from Bos primigenius , it was considered interesting to compare their meat characteristics. For this target, eight animals were used, subdivided into two groups: Podolian group (reared in Italy and slaughtered at 18 months of age) and Katerini group (reared in Greece and slaughtered at 18 months of age). All animals were fed only on local pasture and they were slaughtered in licensed slaughterhouses in their country of birth and they were analysed in the laboratories of the University of Bari in Italy. The results show that the raw meat of Katerini bulls is less red, has higher moisture and is leaner. The fat of this meat is richer in C18:0 and ω3 fatty acids. These data seem to indicate that the meat produced by the breeds studied can satisfy the dietary demands of the modern consumer. As the Katerini breed is threatened with extinction, this study can offer a reason to the local authorities to make a possible future rescue programme, which necessarily passes through a chemical and nutritional characterization of its meat.

Rendimiento y atributos de la carne de pollos criados en cama profunda y al aire libre

Se consideró el rendimiento y atributos sensoriales de la carne de 150 pollos de las lineas Harco Black y Novogen explotados en sistemas de cama profunda y a campo. Las aves, tras 4 semanas de acostumbramiento fueron asignadas a los diferentes sistemas de producción durante un período de 12 semanas. A cada sistema de producción se destinaron 150 pollos (75 por línea), con tres repeticiones de 25 pollos. Las aves en el sistema de cama profunda fueron alimentadas ad libitum; a las aves criadas a campo se les suministró el 50 % de sus necesidades de alimentación diaria. En el día 84, un total de 36 aves fueron seleccionadas al azar para el sacrificio por decapitación y determinar los atributos sensoriales de la carne. Los datos generados se sometieron a un análisis de la varianza de dos vías en un diseño factorial 2×2. Las aves de la línea Novogen en pastoreo consumieron menos pienso (p

Free range and deep litter poultry production systems: effect on performance, carcass yield and meat composition of cockerel chickens

This study was carried out on 150 cockerel chickens each of Harco Black and Novogen strains to determine their performance, carcass yield and meat composition on free range and deep litter production systems. The birds were brooded for 4 weeks and thereafter allotted to the different production systems for a period of 12 weeks. Each production system was allotted 150 chicks (75 chicks per strain) with three replicates of 25 chicks. The birds on deep litter production system were fed ad libitum while each bird on free range was fed 50 % of its daily feed requirement. On the 84 th day, a total of 36 birds were randomly selected for analysis of the carcass yield and meat composition. The data generated were subjected to a two-way analysis of variance in a 2 × 2 factorial experimental arrangement. Novogen strain consumed less feed (P < 0.05) on free range and had the best feed/gain (2.72). A higher (P < 0.05) shear force value (3.74 N) was obtained in the thigh muscle for birds on free range. The tibia proximal length and breadth, and tibia distal length and breadth were significantly (P < 0.05) affected by the production systems and strains. On free range, Harco black had more meat (85.69 g) than bone (18.07 g) in the breast while Novogen had the lowest meat/bone (2.38). Conclusively, Novogen strain should be raised on free range for a better performance in terms of feed/gain, but for higher meat composition, Harco black is a better strain.

Growth performance of different strains of indigenous Tswana chickens under intensive management system

Indigenous Tswana chickens are traditionally kept under free range production system and their growth performance under an intensive management system have not been evaluated. The purpose of this study was therefore to evaluate the growth performance of the naked neck, dwarf and normal-feathered strains of indigenous Tswana chickens under an intensive management system. A total of 74, 43 and 44 Tswana chickens of the normal, dwarf and naked neck strains, respectively, were wing-tagged and evaluated for growth performance (body weight, body length and shank length) from 4 to 20 weeks of age. The chickens were raised under deep litter management system and were fed commercial broiler feeds ad libitum. Sex had a significant (P < 0.05) influence on body weights, shank length and body length of only the normal and naked neck strains. Males of all the strains were generally heavier and had longer bodies and shanks than their age-matched female counterparts. Generally, naked neck males and females were the heaviest and had the longest bodies and shanks, while dwarf males and females were the lightest and had the shortest bodies and shanks. The naked strain had superior growth performance compared to the normal-feathered and dwarf strains. Key words: Growth, Tswana chickens, intensive management.

Optimizing early detection of avian influenza H5N1 in backyard and free-range poultry production systems in Thailand

For infectious diseases such as highly pathogenic avian influenza caused by the H5N1 virus (A/H5N1 HP), early warning system is essential. Evaluating the sensitivity of surveillance is a necessary step in ensuring an efficient and sustainable system. Stochastic scenario tree modeling was used here to assess the sensitivity of the A/H5N1 HP surveillance system in backyard and free-grazing duck farms in Thailand. The whole surveillance system for disease detection was modeled with all components and the sensitivity of each component and of the overall system was estimated. Scenarios were tested according to selection of high-risk areas, inclusion of components and sampling procedure, were tested. Nationwide passive surveillance (SSC1) and risk-based clinical X-ray (SSC2) showed a similar sensitivity level, with a median sensitivity ratio of 0.96 (95% CI 0.40–15.00). They both provide higher sensitivity than the X-ray laboratory component (SSC3). With the current surveillance design, the sensitivity of detection of the overall surveillance system when the three components are implemented, was equal to 100% for a farm level prevalence of 0.05% and 82% (95% CI 71–89%) for a level of infection of 3 farms. Findings from this study illustrate the usefulness of scenario-tree modeling to document freedom from diseases in developing countries.

The Effects of Production Systems (Barn and Free-Range) on Foot Pad Dermatitis and Body Defects of White Turkeys

This study was carried out to determine the effects of barn and free-range production systems on some body defaults and food-pad-dermatitis scores in turkeys.160 malefemale mixed white turkey poults were reared under intensive conditions until 8 weeks of age. The birds were allocated to two groups of compartments with 4 replicates; each replicate contained 11 female and 11 male poults. In the first group, poults were reared under intensive conditions and in the second group, poults had access to a free-range area. At the ages of 18 and 20 weeks, 58 turkeys from two groups were slaughtered and live weight, foot and toe defects, claw enlargement, and foot-pad dermatitis (FPD) scores on right and left feet were determined. Data were subjected to analyses of variance for a fully randomised design. Live weight, age and breeding system data were evaluated by factorial variance analysis and the other data by non-parametric Friedman Test. Differences were determined by the KruskalWallis test in the traits which the interactions were found significant. The Duncan Multiple Comparison Test was applied in the comparison of the groups. Also, the correlations between the traits and live weights were determined by Spearman’s Rho. The effect of production system on the live weight and FPD scores were found to be significant in this study. The free-range system had lower FPD values. Age and sex only affected claw enlargement and live weight. Claw enlargement and live weight were found to be significant by the effect of age x sex interaction. Also, FPD on the right foot was found to be significant by the effect of production system x age x sex interaction.

Food safety in free-range and organic livestock systems: risk management and responsibility.

Animal production systems that offer outdoor access to the animals have become increasingly popular in the Western world due to the growing general discontent of consumers with conventional bioindustrial farming practices. These open production systems offer improved animal welfare but may create new problems for animal health, resulting in increased food safety risks from bacterial, viral, or parasitic infections or environmental contaminants. Examples of these new problems include increased Toxoplasma gondii infections in pigs and high dioxin levels in eggs from free-range hens. In this review, the relation between positive and negative points of free-range and organic livestock production systems is discussed with reference to production in The Netherlands. We investigated how proponents of more animal welfare friendly systems deal with potential negative issues in public and whether any risk communication is used. Generally, we found that the existence of a dilemma is disputed or avoided in communication with the consumer. This avoidance could be detrimental for public trust in alternative animal production systems, should problems occur. To prevent future problems, it will be necessary to communicate about the relevant types and sources of the food safety risks to the consumers. The responsibility for protecting food safety should be properly divided among the various parties involved: producers, processors, governments, nongovernmental organizations, and consumers.

Characteristics of the smallholder free-range pig production system in western Kenya

Free-range pig farming is common amongst the small-scale farmers in western Kenya. In order to determine the characteristics of this type of production system, a cross-sectional questionnaire survey on farm characteristics and management was collected from 182 farmers in Busia District. The mean farm size was one acre, while the mean number of pigs per farm was 3.6. Pigs were mainly kept as a source of income (98%) and majority were of cross breed variety (64%). The production systems included farrow to weaner (12%), porker to finisher (36%), and mixed (46%). Sixty five percent (65%) of the pigs were tethered and housing was not provided in 61% of the farms. Most of the feeds were sourced locally. Lack of castration and delayed weaning of pigs was observed on 49% and 30% of the farms, respectively. The main production constraints included pig diseases (81%) and high cost or lack of feed (81%). Haematopinus suis infestations and worm infections were considered to be the most important diseases by 71% and 55% of the farmers, respectively. Farmers had moderate knowledge on parasitic disease diagnosis with 31% and 62% not having a history of either deworming or spraying pigs with acaricides, respectively. Marketing constraints were common amongst the farmers and included poor prices and inadequate market information. In conclusion, the production system was characterized as low-input with an income objective. Future research and development approaches should focus on the integration of free-range farmers into the country's market chains through access to extension services.

Effect of sex on slaughter performance and meat quality of Ermellinata di Rovigo chickens

In this trial male and female chickens belonging to a dual-purpose Italian breed, Ermellinata di Rovigo (ER), were reared under a free-range production system (June-October) from 47 days of life until slaughter age, at 138 (I age) and 168 (II age) days of age. At both ages, the final body weight, the dressing-out percentage and the ready-to-cook carcass weight were higher (P<0.01) in males. At II age the female carcass showed higher (P<0.01) proportion of breast and lower (P<0.01) proportion of leg. At both ages, the redness index (a*) of breast and thigh were lower (P<0.01) in females, whereas the yellowness index (b*) showed the opposite trend; the females showed higher lipids in breast meat (P<0.05), thigh meat (P<0.01) and skin (P<0.01). The breast tenderness did not change. The results indicate that the ER birds have a different live body weight, slaughter performance and meat quality according to sex, both at I and II age. At 168 days, under the studied environmental conditions, the chickens were in prepubertal period and the sex affected the dressing-out percentage, meat colour and skin lipids in particular.

Crop β -glucanase activity limits the effectiveness of a recombinant cellulase used to supplement a barley-based feed for free-range broilers

1. The supplementation of diets rich in soluble polysaccharides with microbial cellulases and hemicellulases decreases digesta viscosity and promotes broiler performance. 2. In contrast, recent experiments suggest that polysaccharidases are ineffective for improving the nutritive value of pasture biomass used by free-range broilers. However, the feasibility of using cellulases and hemicellulases to improve the utilisation of cereal-based feeds by pastured poultry remains to be established. 3. A study was undertaken to investigate the capacity of a recombinant cellulase from Clostridium thermocellum to improve the nutritive value of a barley-based feed for free-range pastured broilers of the RedBro Cou Nu × RedBro M genotype. 4. The results show that supplementation of a barley-based diet with a recombinant β-glucanase had no effect on the performance of free-range broilers, foraging in legume-based diets from d 28 to 56. In addition, the results confirm that the lack of effect of the recombinant enzyme in improving the nutritive value of the barley-based feed does not result from enzyme proteolysis or inhibition in the gastrointestinal tract. 5. Significantly, β-glucanase activity was identified in the crop of non-supplemented animals. The data suggest that endogenous cellulases originated both from the barley-based feed and from the crop microflora. 6. The results presented here suggest that in older birds of slow-growing genotypes associated with free-range production systems, previously unknown sources of β-glucanases, such as the feed and microbial symbiotic microflora, can affect the effectiveness of exogenous enzymes added to the feed.