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ABSTRACT: Enterococcus cecorum (EC) infection is an emerging endemic disease in UK and global broiler poultry with major economic impact and welfare concerns. There are significant research gaps with regards to EC pathogenesis, source of infection, transmission routes and early detection of disease, which this study aimed to address. In this prospective study, 725 environmental samples were collected from 4 broiler farms (A–D) the day before chick placement (d 1) and through the subsequent crop (d 7, 14, and 21). Cecal swabs were collected from birds that died of natural causes during the study period. A sample of birds that had been found dead or were culled for health reasons, were presented for post-mortem and samples were taken from lesions for EC culture. DNA was extracted from all environmental samples and EC detected using a qPCR and MALDI-TOF. Two EC isolates from diseased birds were inoculated on concrete slabs and incubated at 23°C and 32°C followed by swabbing of concrete culturing and determination of EC cfu at defined time points. Alongside environmental and bird sampling commercially available, smart camera systems were installed in selected houses on each farm to monitor bird activity and distribution. No EC outbreak occurred during the study, however, it was detected by qPCR in 215/725 (29.7 %) of all samples collected. Also, EC DNA was detected on average in 37% of samples collected on d 1, with approx. 88% of samples from chick paper being positive. Despite this, it was only cultured from 3 ceca samples and joint fluids of two infected birds from farm B on d 14 and 21. The survival experiments using isolates from infected chickens showed EC can survive on concrete for at least 21 d. This study provides invaluable insights into transmission pathways and tenacity of EC. Further studies are needed to determine strain characteristics in relation to their ability to cause disease and to further elucidate the sources of infection on poultry farms.

A 35-d study investigated the impact of dietary supplementation with Arginine (Arg) or branched-chain amino acids (BCAA) of broilers receiving low-protein diets whilst infected with mixed Eimeria species. All birds were given the same starter (d0-10) and finisher (d28-35) diets. The 4 grower diets used were a positive control (PC) with adequate protein (18.5%), a low protein diet (NC;16.5% CP), or the NC supplemented with Arg or BCAA. Supplemental AA was added at 50% above the recommended levels. The treatments were in a 4 × 2 factorial arrangement, with 4 diets, with or without Eimeria inoculation on d14. Birds and feed were weighed after inoculation in phases: prepatent (d14-17), acute (d18-21), recovery (d22-28), and compensatory (d29-35). Ileal digesta, jejunum, and breast tissue were collected on d21, 28, and 35. There was no diet × Eimeria inoculation on growth performance at any phase. Infected birds weighed less and consumed less feed (P < 0.05) in all phases. In the prepatent and acute phases, birds on the Arg diets had higher weight gain (P < 0.05) and lower FCR, similar to PC, when compared to NC and BCAA-fed ones. Infection reduced AA digestibility on d21 and 28 (Met and Cys). However, birds that received supplemental AA had higher digestibility (P < 0.05) of their respective supplemented AA on d 21 only. Infected birds had lower (P < 0.05) BO + AT and higher PEPT1 expression on d21. There was a diet × Eimeria interaction (P = 0.004) on gene expression at d28; 4EBP1 genes were significantly downwardly expressed (P < 0.05) in birds fed Arg diet, irrespective of infection. Infected birds exhibited an upward expression (P < 0.05) of Eef2 on d21 and d28 but experienced a downward expression on d35. Supplemental Arg and BCAA had variable effects on growth performance, apparent ileal AA digestibility, and genes of protein synthesis and degradation, but the effect of Arg on promoting weight gain, irrespective of the Eimeria challenge, was more consistent., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

We investigated the effects of supplementing low protein diets with methionine (Met) or threonine (Thr) during a mixed Eimeria (consisting of E. acervulina, E. maxima and E. tenella) challenge in broilers. All birds were fed the same starter diet (d1-9) and finisher diet (d28-35) which met Cobb 500 nutrient specifications. Birds were allocated to 1 of 4 dietary treatments from d9 to 28: a standard protein diet (19% CP); a low protein diet (16% CP); or the low protein diet supplemented with Met or Thr at 50% above recommendations. On d14, half of the birds were challenged, and half of the birds were unchallenged. From d14 to 28, feed intake was recorded daily and BW every 3 or 4 d. Oocyst excretion was measured daily from d18 to 27. On d21 and 28, 3 birds per pen were euthanized to assess nutrient digestibility, cytokine expression and intestinal histology. During the acute stage of the challenge, challenged birds reduced ADFI and ADG (P < 0.05). In the pre-patent and recovery stages, birds given the 16% CP diets increased ADFI (P < 0.05), meanwhile there were no differences in ADG in these stages (P > 0.05). Nutrient digestibility was reduced in challenged birds in the acute stage (P < 0.05) but tended to be greater than in unchallenged birds during the recovery stage. There was no significant effect of diet on oocyst excretion or intestinal histology (P > 0.05). Interactions were observed between diet and challenge on IL-10 and IL-21 expression in the cecal tonsils during the acute stage of the challenge (P < 0.05), due to reduced IL-10 expression in challenged Thr birds and greater IL-21 expression in challenged Met birds. Supplementation with Thr or Met had limited effects on the outcomes of a mixed Eimeria challenge but provides benefits to the host by enhancing their immune response., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

We investigated the effects of supplementing arginine (Arg) and branched-chain amino acids (BCAA) in broilers fed reduced-protein diets and challenged with Eimeria spp. All birds were fed the same starter diet meeting Cobb 500 nutrient specifications from d 1 to 9. Four grower diets: positive control (PC) with 20.0% crude protein (CP); reduced-protein negative control (NC) with 17.5% CP; or NC supplemented with Arg or BCAA at 50% above recommendations (ARG or BCAA) were fed to the birds from d 9 to 28. Birds were allocated in a 2 × 4 factorial arrangement (4 diets, each with or without challenge), with 8 replicates per treatment. On d 14, the challenge groups were orally gavaged with mixed Eimeria spp. Intestinal permeability was higher (P < 0.05) in NC than PC, whereas the permeability of ARG and BCAA groups did not differ significantly from PC. On d 28, a significant interaction (P < 0.01) was observed in CD8 + : CD4 + ratios in cecal tonsils (CT), Eimeria challenge increased the ratios in all groups except for the ARG group. On d 21, a significant interaction was found for CD4 + CD25 + percentages in CT (P < 0.01) that Eimeria challenge increased the percentages only in PC and NC groups. On d 21 and 28, significant interactions (P < 0.01) were found for macrophage nitric oxide (NO) production. In nonchallenged birds, NO was higher in the ARG group than other groups, but in challenged birds, NO was higher in both ARG and BCAA groups. On d 21, a significant interaction was found for bile anticoccidial IgA concentrations (P < 0.05) that Eimeria challenge increased IgA only in NC and ARG groups. The results suggest that a reduced-protein diet exacerbates the impact of the Eimeria challenge on intestinal integrity, but this could be mitigated by Arg and BCAA supplementations. Arginine and BCAA supplementations in reduced-protein diets could be beneficial for broilers against Eimeria infection by enhancing the immune responses. The beneficial effects of Arg supplementation tended to be more pronounced compared to BCAA supplementation., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

A systematic review and meta-analysis was conducted to investigate the role of Eimeria species, dose and inoculation time, on performance and infection outcomes of different broiler strains infected for different study durations. The meta-analysis addressed E. acervulina, E. maxima, E. tenella, and mixed species infections, and involved data from 72 peer-reviewed articles, corresponding to 521 treatments performed on 20,756 broilers. A secondary objective was to investigate the effects of synthetic anticoccidials, ionophores, and vaccination against Eimeria on the above outcomes. Performance during infection was scaled (%) to that of the uninfected birds. Infection reduced scaled ADFI and ADG (P < 0.001) and increased feed conversion ratio (FCR; P < 0.05); there was a significant interaction between dose and species on scaled ADFI and ADG, suggesting that different species affected these variables to different extents (P < 0.001). There was a tendency for an interaction between dose and broiler strain on scaled ADFI (P = 0.079), and a significant interaction between these variables on scaled ADG (P < 0.01). A tendency for an interaction between oocyst dose and Eimeria species (P = 0.067) on maximum number of oocysts excreted was observed. Lesion scores were significantly affected by dose, species, and their interaction (P < 0.05), the latter caused by an increase in the lesion scores during E. maxima and E. tenella infections. Control methods significantly affected scaled ADG and FCR (P < 0.05) and there was an interaction between dose and control methods on ADFI (P < 0.001). Synthetic anticoccidial use improved scaled ADG (P < 0.01), whereas ionophores improved FCR compared with untreated birds (P < 0.01). An interaction between dose and control method on scaled ADFI was caused by the higher ADFI of vaccinated compared to untreated birds, as dose increased. There was a significant effect of control methods on lesion scores (P < 0.01). All findings advance our understanding of the factors that influence the impact of coccidiosis and its controls in broilers., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

In 2 experiments, we investigated whether diet composition plays a role in pathogen-induced anorexia, the voluntary reduction in ADFI during infection in broilers. We hypothesized that either energy or CP dietary content could influence the extent of anorexia in Ross 308 broilers and infection outcomes with Eimeria maxima. From d 13 of age, half of the birds were infected, and half were uninfected. ADFI was measured daily, and BW every 3 d until d 29. Oocyst excretion was measured daily from d 17 to 23. The impact of parasitism on the small intestine was assessed on d 19 and 25. In Experiment 1, 336 birds were offered diets progressively diluted with lignocellulose, starting from a diet with 3,105 (kcal ME/kg) and 20% CP. There was a significant interaction between infection and diet on ADFI during the acute stage of infection (d 17 to 21): for control birds diet dilution decreased ADFI and consequently reduced energy and CP intake. For infected birds, diet dilution increased ADFI, leading to the same energy and CP intake across diets. Oocyst excretion and villi length to crypt depth ratio (VCR) were constant across infected treatments. In Experiment 2, 432 birds were offered diets with constant ME (3,105 kcal/kg), but different CP contents (24, 20, 26, and 12%). Infection significantly reduced ADFI. Although there was no interaction between infection and diet on ADFI, there was an interaction on CP intake during the acute stage of infection. Infected birds on the 20% CP diet achieved the same CP intake as uninfected birds. There were no differences in the VCR and ADG of the infected birds on 24, 20 and 16% CP treatments, but birds on 12% had the lowest ADG and excreted more oocysts. We suggest that during infection, birds target a nutrient resource intake, which appears to be beneficial for infection outcomes, while at the same time they avoid excess protein intake. We conclude that different mechanisms regulate ADFI in infected and uninfected birds., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The use of alternative, often bulky ingredients is becoming widespread in poultry diets as the industry seeks to reduce its economic and environmental costs. Consequently, there is an increased need to accurately predict the performance of birds given such diets and identify their maximum capacity for bulk. We offered diets diluted with a range of bulky ingredients to male Ross 308 broilers to assess their capacity for bulk and identify a bulk characteristic responsible for limiting intake. Four hundred ninety-five day-old broilers allocated into 45 pens, were offered a common starter diet until day (d) 7, and 1 of 9 grower diets from d 8 to 29 (Period 1). Each of the grower diets was diluted with either 30 or 60% of oat hulls (OH), wheat bran (WB), or grass meal (GM), or a mixture of 2 bulky ingredients at an inclusion level of 30% each (OHWB, OHGM, WBGM). From d 29 to 43 (Period 2), all birds were offered the bulkiest diet (GM60). A number of bulk characteristics were measured on the diets. Feed intake was measured daily, and birds were dissected on d 29 and 43 for organ and carcass measurements. During d 8 to 14 diet water-holding capacity (WHC) was more consistent in predicting feed intake when scaled per unit of body weight than any other bulk characteristic. However, this was no longer the case during d 15 to 28. In Period 2, the response and adaptation to the bulkiest diet was determined by previous experience to bulk. Birds offered a bulkier diet during Period 1, were better able to adapt the size of their digestive organs and increase scaled feed intake, such that there were no differences between these birds and those offered the GM60; the converse was the case for birds on the least bulky diets. We conclude that WHC is able to predict maximum intake on bulky diets in unadapted birds. Adaptation to bulky diets can be very fast, so that their high bulk content no longer limits feed intake and performance., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The view that genetic selection for carcass yield has limited the size of the gastrointestinal tract (GIT) of modern broilers has sparked concerns that their capacity to cope with energy dilution or bulk is also limited. We investigated the capacity of male Ross 308 broilers to deal with increasing levels of bulk and aimed to identify a feed bulk dimension responsible for limiting feed intake (FI). About 528 day-old broilers were allocated to 48 pens and offered a common starter feed until day 8, and 1 of 7 feeds from day 8 to 36 of age: a basal control (B), which was diluted to 3 levels (15, 30, or 45%) with either oat hulls (OH) or sugar beet pulp (SBP). Feed intake was measured daily and birds were dissected for GIT measurements at day 15, 22, and 36. Feed intake increased in birds offered OH15 (135 g/d), OH30 (140 g/d), and SBP15 (138 g/d) compared with birds offered the B feed (106 g/d; SEM 2.4). By increasing FI, birds were able to compensate for the lower energy content of their feeds. The greatest increase in FI was seen on OH30: its energy content (2,273 kcal/kg) was 26% lower than the B feed (3,081 kcal/kg). There was evidence of adaptation on the bulky feeds, as during the last week only birds on SBP45 were limited in FI and performance. The relative weights of the GIT were greater in the SBP than OH series, suggesting that the former needed to accommodate a higher bulk intake. For the OH series the increase in the relative GIT weights was confined to the gizzard and small intestine; whereas for the SBP series, the increase was extended to proventriculus and large intestine. Because only SBP45 was limiting FI, we were unable to identify a bulk dimension to be used to predict FI. Our data reject the suggestion that modern broilers have a reduced ability to cope with reductions in feed energy content., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Coccidiosis and rapid growth rate (GR) compromise bone mineralization in modern broilers. We tested the hypothesis that reducing GR via diet dilution during peak bone development will improve bone mineralization in both infected and uninfected broilers. A total of 384 male Ross 308 chicks were allocated to a basal grower diet (3,107 kcal/kg ME and 19.4% CP) diluted with 0, 5, 10, or 15% lignocellulose (n = 12 pens/treatment, 8 birds/pen) at day 10 of age. Prior to this, birds in each group received half the intended diet-dilution levels (day 8 to 10 of age) and a common starter diet (day 1 to 7 of age). At day 13 of age (day 0 post-infection, pi), birds were orally inoculated with either 7,000 sporulated Eimeria maxima oocysts (I) or water (C), forming a 4 diet-dilution level × 2 infection status factorial experiment. Performance was measured over 12 days pi and scaled to BW at infection (day 0 pi) to account for a priori BW differences. At day 12 pi (day 25 of age), 1 bird/pen (a total of 6 birds/treatment) was sampled to assess tibia and femur mineralization relative to BW, and carcass yield. There was no interaction (P > 0.05) between infection status and diet-dilution level on ADFI/BW measured over day 1 to 12 pi, or on any bone variable. ADG/BW pi decreased (P < 0.01) with diet dilution amongst C birds, but was statistically similar (P > 0.05) amongst I birds. I compared to C birds had reduced breast meat (P < 0.05) and eviscerated carcass yield (P < 0.01), femur (P < 0.05) and tibia (P < 0.01) breaking strength (BS), and femur ash weight (AW) (P < 0.05). Diet dilution did not affect carcass yield, but improved femur BS (P < 0.001), and tended to improve (P < 0.1) femur and tibia AW. Overall, diet dilution significantly affected femur, more than tibia, variables: relative BS, robusticity index, and ash percentage. Reducing GR affected broiler long bone mineralization to a similar degree in the presence or absence of coccidiosis., (© 2019 Poultry Science Association Inc.)

Coccidiosis penalizes calcium (Ca), phosphorus (P), and fat-soluble vitamin status, as well as bone mineralization in broiler chickens. We hypothesized that dietary vitamin D (VitD) supplementation in the form of 25-hydroxycholecalciferol (OHD), compared to cholecalciferol (D3), would improve bone mineralization in broilers receiving marginally deficient Ca/P diets, with more pronounced effects during malabsorptive coccidiosis. In a 2 VitD source × 2 Ca/P levels × 2 levels of infection factorial experiment (n = 6 pens per treatment, 6 birds/pen), Ross 308 broilers were assigned to an Aviagen-specified diet supplemented with 4,000 IU/kg of either OHD or D3 between days 11 and 24 of age. The diet contained adequate (A; 8.7:4.4 g/kg) or marginally deficient (M; 6.1:3.1 g/kg) total Ca and available (av)P levels. At day 12 of age, birds were inoculated with water (C) or 7,000 Eimeria maxima oocysts (I). Pen performance was measured over 12 days post-infection (pi). One bird per pen was assessed for parameters of bone mineralization and intestinal histomorphometric features (day 6 and 12 pi), as well as E. maxima replication and gross lesions of the small intestine (day 6 pi). There was no interaction between infection status and Ca/avP level on bone mineralization. Bone breaking strength (BS), ash weight (AW), and ash percentage (AP) were highest in broilers fed the OHD-supplemented A diets irrespective of infection status. Eimeria maxima infection impaired (P < 0.05) ADG and FCR pi; Ca and P status at day 6 pi; OHD status, BS, AW, and AP at day 12 pi; and intestinal morphology at day 6 and 12 pi. A- compared to M-fed broilers had higher BS, AW, and AP at day 6 pi, and AW at day 12 pi. VitD source affected only OHD status, being higher (P < 0.001) for OHD- than D3-fed broilers at day 6 and 12 pi. In conclusion, offering OHD and adequate levels of Ca and P improved bone mineralization, with no effect on performance. Dietary D3 and OHD supplemented at 4,000 IU/kg had similar effects on coccidiosis-infected and uninfected broilers, which led to the rejection of our hypothesis., (© 2019 Poultry Science Association Inc.)

We hypothesized that performance and bone mineralization of 2 broiler lines will benefit from increasing vitamin D (vitD) supplementation above current commercial levels and by partial substitution of D3 by 25-OH-D3. Male Ross 308 and 708 chicks (n = 576), were offered diets with low (LD; 1,000), medium (MD; 4,000) or high levels of D3 (HD; 7,000 IU/kg), and medium levels of vitD where the majority of D3 was substituted by 25-OH-D3 (25MD; 1,000 D3+3,000 25-OH-D3 IU/kg). Performance was measured at the end of starter (day 10), grower (day 24), and finisher periods (day 38). Three birds per pen were dissected at the end of each period to assess tibia and femur ash percentage (%), ash weight, bone breaking strength (BBS), and serum levels of 25-OH-D3. Remaining birds were gait scored (GS) at day 37 of age. Genotype and diet did not interact for any trait, whilst performance was not affected by diet. Ross 708 had lower body weight (P < 0.005), higher feed conversion ratio over the grower period (P < 0.05), similar levels of 25-OH-D3, but higher GS (P < 0.05) than Ross 308. Serum 25-OH-D3 levels were affected by diet at the end of the starter and grower periods (P < 0.05), being lowest for LD and highest for 25MD. Diet affected GS (P < 0.01), being higher in LD than 25MD. Femur ash % was higher at the end of the starter and grower periods for 25MD than LD and for both HD and 25MD than LD (P < 0.05). Femur and tibia ash weight were higher for 25MD in comparison to LD birds (P < 0.05) at the end of the grower period. Femur and tibia BBS were higher (P < 0.05) for 25MD in comparison to LD at the end of the grower and finisher periods, respectively. Overall, effects of vitD supply were more pronounced for femur than for tibia mineralization. Results do not suggest supplementation of vitD above current maximum levels and support partial substitution by 25-OH-D3.

A system approach-based Life Cycle Assessment (LCA) framework, combined with a simple mechanistic model of bird energy balance was used to predict the potential effects of 15 y prospective broiler breeding on the environmental impacts of the standard UK broiler production system. The year 2014 Ross 308 genotype was used as a baseline, and a future scenario was specified from rates of genetic improvement predicted by the industry. The scenario included changes in the traits of growth rate (reducing the time to reach a target weight 2.05 kg from 34 d to 27 d), body lipid content, carcass yield, mortality and the number of chicks produced by a breeder hen. Diet composition was adjusted in order to accommodate the future nutrient requirements of the birds following the genetic change. The results showed that predicted changes in biological performance due to selective breeding could lead to reduced environmental impacts of the broiler production chain, most notably in the Eutrophication Potential (by 12%), Acidification Potential (by 10%) and Abiotic Resource Use (by 9%) and Global Warming Potential (by 9%). These reductions were mainly caused by the reduced maintenance energy requirement and thus lower feed intake, resulting from the shorter production cycle, together with the increased carcass yield. However, some environmental benefits were limited by the required changes in feed composition (e.g., increased inclusion of soy meal and vegetable oil) as a result of the changes in bird nutrient requirements. This study is the first one aiming to link the mechanistic animal modeling approach to predicted genetic changes in order to produce quantitative estimates of the future environmental impacts of broiler production. Although a more detailed understanding on the mechanisms of the potential changes in bird performance and their consequences on feeding and husbandry would be still be needed, the modeling framework produced in this study provides a starting point for predictions of the effects of prospective genetic progress., (© 2015 Poultry Science Association Inc.)

The environmental impacts of 2 alternative UK broiler production systems that aim to improve bird welfare (a lower stocking density indoor system and the same system combined with heat exchangers for ventilation air) were compared with the baseline standard indoor system of broiler production. Furthermore, the environmental impacts of egg production in the conventional battery cage system (banned in the European Union in 2012) and its replacement, the enriched colony cage system, were compared. All comparisons were based on data obtained from the UK poultry industry, and the life cycle assessment method from cradle to farm gate was applied in the analyses. The results show that the lower density system slightly increased the global warming potential (GWP) of broiler production (by 2%), compared with the standard indoor system, due to increased heating requirements. However, when combined with the heat exchanger, the GWP was actually reduced by 3% when compared with the standard system. Both alternative systems for broilers resulted in a reduction in the eutrophication potential (by up to 8%) and acidification potential (by up to 10%). The results also showed that the colony cage system had 8% lower primary energy use and 3% lower GWP than the baseline cage system, due to better energy use efficiency and slightly improved productivity. There were only minor differences in the eutrophication and acidification potentials between different egg production systems. The results suggest that welfare-friendly changes in chicken systems can be achieved without a compromise in their environmental impacts.

The aim of this study was to apply the life cycle assessment (LCA) method, from cradle to gate, to quantify the environmental burdens per 1,000 kg of expected edible carcass weight in the 3 main broiler production systems in the United Kingdom: 1) standard indoor, 2) free range, and 3) organic, and to identify the main components of these burdens. The LCA method evaluates production systems logically to account for all inputs and outputs that cross a specified system boundary, and it relates these to the useful outputs. The analysis was based on an approach that applied a structural model for the UK broiler industry and mechanistic submodels for animal performance, crop production, and major nutrient flows. Simplified baseline feeds representative of those used by the UK broiler industry were used. Typical UK figures for performance and mortality of birds and farm energy and material use were applied. Monte Carlo simulations were used to quantify the uncertainties in the outputs. The length of the production cycle was longer for free-range and organic systems compared with that of the standard indoor system, and as a result, the feed consumption and manure production per bird were higher in the free-range and organic systems. These differences had a major effect on the differences in environmental burdens between the systems. Feed production, processing, and transport resulted in greater overall environmental impacts than any other components of broiler production; for example, 65 to 81% of the primary energy use and 71 to 72% of the global warming potential of the system were due to these burdens. Farm gas and oil use had the second highest impact in primary energy use (12-25%) followed by farm electricity use. The direct use of gas, oil, and electricity were generally lower in free-range and organic systems compared with their use in the standard indoor system. Manure was the main component of acidification potential and also had a relatively high eutrophication potential. The LCA method allows for comparisons between systems and for the identification of hotspots of environmental impacts that could be subject to mitigation.

The aim of this study was to apply a life cycle assessment (LCA) method, from cradle to gate, to quantify the environmental burdens per 1,000 kg of eggs produced in the 4 major hen-egg production systems in the United Kingdom: 1) cage, 2) barn, 3) free range, and 4) organic. The analysis was based on an approach that applied a structural model for the industry and mechanistic submodels for animal performance, crop production, and nutrient flows. Baseline feeds representative of those used by the UK egg production industry were used. Typical figures from the UK egg production industry, feed intake, mortality of birds, farm energy, and material use in different systems were applied. Monte Carlo simulations were used to quantify the uncertainties in the outputs and allow for comparisons between the systems. The number of birds required to produce 1,000 kg of eggs was highest in the organic and lowest in the cage system; similarly, the amount of feed consumed per bird was highest in the organic and lowest in the cage system. These general differences in productivity largely affected the differences in the environmental impacts between the systems. Feed production, processing, and transport caused greater impacts compared with those from any other component of production; that is, 54 to 75% of the primary energy use and 64 to 72% of the global warming potential of the systems. Electricity (used mainly for ventilation, automatic feeding, and lighting) had the second greatest impact in primary energy use (16-38%). Gas and oil (used mainly for heating in pullet rearing and incineration of dead layer birds) used 7 to 14% of the total primary energy. Manure had the greatest impact on the acidification and eutrophication potentials of the systems because of ammonia emissions that contributed to both of these potentials and nitrate leaching that only affected eutrophication potential. The LCA method allows for comparisons between systems and for the identification of hotspots of environmental impacts that could be subject to mitigation.

Current selection goals in broiler breeding focus on the improvement of live performance traits, such as feed intake, BW, and feed conversion ratio (FCR). The use of electronic feeders allows measurement of feed intake of individuals housed in groups as well as the identification of different feeding behaviors. Feed intake can thus be split into underlying feeding behavior traits, allowing the estimation of genetic correlations and assessment of the genetic consequences of selecting for performance traits on feeding behavior traits. To investigate the genetic relationships between performance traits and feeding behavior, data of visits to feeders by birds from 4 lines of broilers that differed in selection focus on growth and FCR were analyzed. Visits were recorded electronically and grouped into meals using an existing model for estimating meal criteria. Mean individual feeding behavior traits were then calculated across the entire test period (2 to 5 wk of age). Records were available for between 14,000 and 18,000 birds/line. Analyzed feeding behavior traits were meals per day, meal size, visits per meal, meal duration, nonfeeding time in meal, time feeding per day, proportion of meal spent feeding, feeding rate, and ADFI. Analyzed performance traits were 35-d BW, total feed intake over the entire test period, and FCR. All feeding behavior traits showed moderate to high heritabilities (0.24 to 0.57) but low genetic correlations with performance traits (-0.20 to 0.18), except for ADFI, which was moderately correlated with total intake on test (0.57) and highly correlated with FCR (0.91). The low genetic correlations indicate that the difference in selection intensity among lines for these performance traits has had limited effect on feeding behavior. Different feeding strategies that would result in favorable breeding values for FCR were identified, adding opportunities for further improvements in feed efficiency within and across environments.

In this study, we evaluated the growth performance and antioxidant status of broiler chicken supplemented with the edible mushroom Agaricus bisporus. Ninety 1-d-old female broiler chickens randomly allotted to 3 dietary treatments were given either a nutritionally balanced basal diet or the basal diet supplemented with 10 or 20 g of dried mushroom/kg of feed for 6 wk on an ad libitum basis. Body weight, feed intake, and feed conversion ratio values were monitored weekly. To evaluate the antioxidant status of broiler chicken, refrigerated liver, breast, and thigh tissues were assayed for levels of glutathione, reduced glutathione, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, as well as malondialdehyde at 6 wk of age. Results showed that dietary mushroom supplementation at both inclusion levels was accepted well by the broiler chicken and improved feed efficiency compared with the control diet. Dietary mushroom inclusion at 20 g/kg improved both growth performance and feed efficiency compared with control diet at 42 d of age. Dietary mushroom at both inclusion levels reduced malondialdehyde production in liver, breast, and thigh tissues and elevated glutathione peroxidase, reduced glutathione, glutathione reductase, and glutathione S-transferase compared with the control treatment, the effects being dose-dependent. These results suggest that A. bisporus mushroom exerts both a growth-promoting and tissue antioxidant-protective activity when supplemented in broiler chicken diets.

Selection for increased growth rate in livestock is accompanied by increased requirements for food resources. It has been suggested that more intensively selected birds, such as broilers, have altered food intake control mechanisms and may be constantly hungry, due to the high demands of fast growth rates. If this is the case, it would be a major welfare issue. We investigated the hypothesis that more intensive selection for growth in some lines of broilers has altered feeding behavior by analyzing short-term feeding behavior bouts in relation to the roles of hunger and satiety mechanisms in the control of food intake. Using 4 genetic lines, resulting from different levels of selection for growth rate, meal pattern analysis was performed and the bouting of short-term feeding behavior was estimated. All lines showed bouted feeding behavior, although differences in meal size, number of meals, and meal duration were evident across lines. In all lines, the probability of birds starting a new meal was low immediately after finishing the previous meal and increased with time, as expected for feeding behavior governed by hunger and satiety mechanisms. Normal feeding behavior was, therefore, not affected by the intensity of selection. Feeding rate increased with growth rate, suggesting that this may be a consequence of selection. However the other characteristics of feeding behavior, such as meal duration, did not change consistently with higher growth rate. Due to differences between lines in bird size, the number and weight of birds per pen also differed between the lines. The differences in feeding behavior between lines were greatly diminished when weight of birds per square meter was taken into account but were still statistically significant. Overall, it is apparent that even when growth rate and body size have been substantially altered by genetic selection, the underlying normal controls of feeding behavior are conserved in broiler birds.

To prevent health and fertility problems associated with excessive weight gain, broiler breeders are severely feed restricted during rearing, which may affect welfare. We compared the effects of an experimental ad libitum feeding regimen based on qualitative restriction of food intake with conventional quantitative food restriction on the performance of female broiler breeders during rearing and lay. During rearing up to 20 wk of age, control birds were fed restricted amounts of standard broiler breeder mash once daily. Experimental birds had ad libitum access to the same standard mash mixed with 400 g of oat hulls/kg of feed and increasing concentrations of Ca propionate, an appetite suppressant. Mean total mash intake during rearing was 8.12 kg and did not differ between treatments. Both control and experimental birds showed an almost linear growth curve, treatment mean body weights were always within 100 g of the target weight line, and treatments did not differ for body weight uniformity. Groups were subjected to the same quantitative feed restriction from during lay. Feeding regimen during rearing did not affect number of eggs produced, egg weight, or egg quality up to 46 wk of age. We concluded that it may not be necessary to subject chicks to severe quantitative feed restriction to achieve desirable growth curves and body weight uniformity during rearing. Qualitative restriction of feed intake can achieve desirable growth curves in ad libitum fed chicks during rearing, and such a feeding regimen does not have negative effects on hen performance during lay.