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Problems with indoor husbandry and immunological challenges are some of the stressors that broilers may face which can affect production. Infectious diseases can compound the effects of excessive concentrations of ammonia causing respiratory and ocular inflammation and increased lacrimal production in broiler chickens. The objectives of this investigation were to establish normal values of tear production in chicks and compare the practicality of the different methods. Palpebral fissure length (PFL) and tear production were evaluated in Cobb 500 chicks at 5 d old and then at 5 d of age by the following methods: modified Schirmer's test I (mSTT1), phenol red cotton thread tear test (PRCTTT), and standardized endodontic absorbent paper point test (EAPPTT). Ten chicks at the age of 5 and 42 d were evaluated for each method. In addition, at 42 d, when the palpebral fissure permitted, a regular-sized Schirmer tear test I (STT1) was performed in another group of 10 chickens. Overall, PFL and the secretion of the aqueous phase of the tear film increased with age. Mean mSTT1 results were 5.00 ± 1.83 mm and 10.45 ± 2.58 mm for 5- and 42-d-old chicks, respectively. Mean PRCTTT results were 12.37 ± 1.80 mm and 25.58 ± 4.8 mm for 5- and 42-d-old chicks, respectively. Mean EAPPTT results were 7.13 ± 0.72 mm and 12.03 ± 0.92 mm for 5- and 42-d-old chicks, respectively. Mean STT1 for 42-d-old chicks was 11.40 ± 2.60 mm. Results obtained with endodontic paper points showed the lowest coefficient of variation and investigators found the test easier to perform. These values reported for broilers at different ages may be applied in poultry ophthalmology to help the diagnosis of lacrimal production disorders and to detect early disease symptoms that could cause economic losses in poultry production.

The effects of formulating broiler diets that contain sources of either rapidly or slowly digestible protein and 2 different dietary fiber sources on growth performance were studied in broilers chickens from 0 to 36 d of age. A total of 1,920 one-day-old, male Ross 708 broiler chickens were randomly allocated and housed in 48 floor pens (40 birds/pen) to one of 4 dietary treatments. Birds were allotted according to a completely randomized block design using a factorial arrangement of treatments with 2 protein digestion rates (rapidly or slowly) and 2 dietary fiber sources [3% oat hulls (OH) or 3% sugar beet pulp (SBP)] from 0 to 36 d of age. All diets were formulated to be isocaloric and isonitrogenous. The pen was the experimental unit for all variables studied (12 replicates/treatment). Data were analyzed using the MIXED procedure of SAS, and the model included the main effects of the protein digestion rate, dietary fiber source, and their interaction. There were 3 experimental feeding phases; starter (from day 0-14), grower (from day 14-28), and finisher (from day 28-36). Results indicated that broilers fed diets containing sources that supplied more rapidly digestible protein had 4% greater (P < 0.01) ADG and improved (P < 0.01) the feed conversion ratio (FCR) by 5% throughout the experiment, most notably after the starter phase. Diets containing 3% OH increased (P < 0.05) the ADFI and ADG (P < 0.05) in the starter phase compared with broilers fed diets containing 3% SBP, without affecting the FCR. The ADG and FCR of broilers fed diets containing sources of slowly digestible protein were improved (P < 0.05) to the level of broilers fed rapidly digestible protein containing diets with the addition of 3% OH. It is concluded that broiler diets should be formulated to contain a high concentration of ingredients that supply rapidly digestible protein, but if this is cost-prohibitive, then 3% OH could be used to increase the ADFI and ADG and potentially protein digestion rates to reduce the FCR.

Feather pecking is a multi-factorial behavioral disorder and a serious welfare issue in the poultry industry. Several studies report early life experience with litter to be a major determinant in the development of feather pecking. The current study aimed to test the large-scale on-farm efficiency of a simple and cheap husbandry procedure applied during the rearing period with the ultimate goal of reducing the incidence of feather pecking and plumage damage during the production stage in laying hens. Five laying hen-rearing farmers from across Norway participated in the study. These farmers were asked to create divisions within their hen rearing houses and to separate their chicks into 2 groups: one reared with access to a paper substrate from the first d of age, the other a control group without access to paper substrate during rearing. All flocks were visited at the production farms at 30 wk of age and observed for pecking behavior and feather damage. Birds in the control group had higher odds of having more feather damage compared to the birds from the treatment group. In addition, flocks provided with environmental enrichment at the production farms had a reduced incidence of feather pecking, irrespective of the treatment. These results indicate that husbandry procedures during both rearing and production stages have the potential to alleviate feather pecking and increase laying hen welfare.

This paper is an integral part of the special publication series that arose from the multidisciplinary and multi-institutional project of the Coalition for Sustainable Egg Supply (CSES). The CSES project involves 3 housing systems for egg production at the same research farm site in the Midwest, USA, namely, a conventional cage (CC) house, an aviary (AV) house, and an enriched colony (EC) house. The CC house (141.4 m L × 26.6 m W × 6.1 m H) had a nominal capacity of 200,000 hens (6 hens in a cage at a stocking density of 516 cm2/hen), and the cages were arranged in 10 rows, 8 tiers per cage row, with a perforated aisle walkway at 4-tier height. The AV house (154.2 m L × 21.3 m W × 3.0 m H) and the EC house (154.2 m L × 13.7 m W × 4.0 m H) each had a nominal capacity of 50,000 hens. The AV house had 6 rows of aviary colonies, and the EC house had 5 rows of 4-tier enriched colonies containing perches, nestbox, and scratch pads (60 hens per colony at a stocking density of 752 cm2/hen). The overarching goal of the CSES project, as stated in the opening article of this series, was to comprehensively evaluate the 3 egg production systems from the standpoints of animal behavior and well-being, environmental impact, egg safety and quality, food affordability, and worker health. So that all the area-specific papers would not have to repeat a detailed description of the production systems and the management practices, this paper is written to provide such a description and to be used as a common reference for the companion papers.

Genetic selection that has been carried out for several dozen years has led to significant progress in poultry production by improving productive traits and increasing the profitability of broiler breeder and layer hen production. After hatching, broilers and layers differ mainly in feed intake, growth rate, efficiency of nutrient utilization, and development of muscles and adipose tissue. A key role can be played by hormonal mechanisms of appetite control in broilers and layers. The paper discusses the consequences of different growth rates resulting from long-term genetic selection on feed intake, efficiency of nutrient utilization, and development of muscles and adipose tissue, with particular consideration of the hormonal mechanisms of appetite control in broilers and layers. The information presented in this review paper shows that it would be worth comparing these issues in a meta-analysis.

This paper presents the results of the research on the use of fish oil (FO) in combination with soybean oil (SO) in laying hens diet on physical and chemical properties of fresh eggs and those stored in a refrigerator for 28 d at + 4°C. Fatty acids (FA) profile, as well as thiobarbituric acid reactive substances (TBARS) values in yolks are also presented. The following feeding treatments have been used: C (control, without FO), E1 (0.3% FO + 4.7% SO), E2 (0.6% FO + 4.4% SO), E3 (0.9% FO + 4.1% SO), E4 (1.2% FO + 3.8% SO) and E5 (1.5% FO + 3.5% SO). Laying hens diets were balanced at the level of 176.10 g/kg crude protein and 11.50 MJ/kg ME. The results of the study showed that feeding treatments affected the relative shares of the eggs basic parts (P < 0.05). The egg storage duration significantly reduced Haugh units (HU), egg and albumen egg weight, and increased the yolk color intensity (P < 0.001). Fish oil share increment in the diets resulted in the EPA (eicosapentaenoic FA) content increase from 10.27 to 20.10 mg/100 g egg; DHA (docosahexaenoic FA) from 105.44 to 236.87 mg/100 g egg and ∑ n-3 PUFA (polyunsatureated FA) from 204.59 to 327.35 mg/100 g egg. The ∑ n-6 PUFA/∑ n-3 PUFA ratio decreased from 8.69 (C group) to 4.54 (E5 group). TBARS values were affected by feeding treatments as well as treatment-storage interactions (P < 0.01).

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers, processors, and retailers to improve the welfare of the billions of chickens processed annually. Several small-scale studies have reported better welfare outcomes for slower-growing strains compared to fast-growing, conventional strains. However, these studies often housed birds with range access or used strains with vastly different growth rates. Additionally, there may be traits other than growth, such as body conformation, that influence welfare. As the global poultry industries consider the implications of using slower growing strains, there was a need for a comprehensive, multidisciplinary examination of broiler chickens with a wide range of genotypes differing in growth rate and other phenotypic traits. Tomeet this need, our team designed a study to benchmark data on conventional and slower-growing strains of broiler chickens reared in standardized laboratory conditions. Over a 2-year period, we studied 7,528 broilers from 16 different genetic strains. In this paper, we compare the growth, efficiency, and mortality of broilers to one of two target weights (TW): 2.1 kg (TW1) and 3.2 kg (TW2). We categorized strains by their growth rate to TW2 as conventional (CONV), fastest-slow strains (FAST), moderate-slow strains (MOD), and slowest-slow strains (SLOW). When incubated, hatched, housed, managed, and fed the same, the categories of strains differed in body weights, growth rates, feed intake, and feed efficiency. At 48 d of age, strains in the CONV category were 835 to 1,264 g heavier than strains in the other categories. By TW2, differences in body weights and feed intake resulted in a 22 to 43-point difference in feed conversion ratios. Categories of strains did not differ in their overall mortality rates. Global Animal Partnership, Canada First Research Excellence Fund, Ontario Agri-Food Innovation Alliance, and Protekta

The paper aimed to study the effects of light regime during the incubation on hatching performance, body development and serum biochemical indexes in Beijing You Chicken (BYC). A total of 1,408 BYC eggs were randomly allocated into 4 groups: 24 h dark as the control (Inc24D); 3 light regimes were 8 h light and 16 h dark group (Inc8L:16D); 12 h light and 12 h dark group (Inc12L:12D); 16 h light and 8 h dark group (Inc16L:8D), respectively. There were 352 eggs in each group, 4 replicates each group and 1 tray each replicate, 88 eggs each tray. Light-emitting diode (LED) strips, white light with temperature of 4,500 to 5,000 K, 150 to 200 lx were set up. The results showed that light regimes had no significant effects on hatching rate of eggs, hatching rate of fertile eggs and healthy rate of chicks (P > 0.05), but the hatching rate of eggs was the lowest in the Inc24D group (87.22%), and the highest in the Inc12L:12D group (93.64%); Lighted incubation significantly affected the incidence of leg problems of 1-day-old chicks (P < 0.05). The incidence rate of leg problems was the highest in the Inc24D group (4.21%), and was decreased in Inc12L:12D and Inc16L:8D groups (P < 0.05). Femur length in the Inc12L:12D group was greater than that in the Inc24D and Inc16L:8D groups (P = 0.011), but there were no differences between Inc8L:16D group and other three groups (P > 0.05). The relative brain weight of 1-day-old chicks was higher in Inc24D and Inc16L:8D groups than in Inc8L:16D group (P = 0.052), but had no difference with Inc12L:12D group. Light regimes during incubation had no effects on serum total protein, albumen, globulin, and urea nitrogen content of 1-day-old chicks (P > 0.05), while the globulin content in Inc12L:12D group was numerically greater than in other three groups (P = 0.063). Lysozyme content in Inc12L:12D group was higher than that in the Inc24D and Inc8L:16D groups (P < 0.05), but had no difference with that in Inc16L:8D group. Light regime had no effect on serum total antioxidant capability (T-AOC) (P > 0.05), but significantly affected the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) (P < 0.05). The GSH-Px and T-SOD activities in the Inc12L:12D group were higher than those in the Inc24D and Inc8L:16D groups. The MDA content of Inc24D was the highest (9.67 nmol/mL) compared to the others, which was very close to the significant level (P = 0.056). In conclusion, 12 h light and 12 h dark incubation has the potential to improve the hatching performance of BYC eggs, benefit for the long bone development, improve some serum immune and antioxidant indexes, and reduce the leg problems in 1-day-old chicks.

Scoring is a common method to evaluate eggshell translucency, and it mainly depends on the area and the density of translucent spots in eggshells. However, the lack of common scoring criteria and the difficulty of quantitatively measuring spots in eggshells impede effective comparisons between research papers and greatly hinder the progress of research on translucent eggshell. To make measurement of translucent eggshells more objective, we optimized the scoring method and compared it with 2 new methods: grayscale recognition and the colorimeter method. Briefly, a total of 354 eggs from 600, 395-day-old dwarf brown laying hens were collected and classified into 4 score groups according to their degree of translucency. This subjective process was repeated 5 times. Then, we captured the profile side of each egg using a camera and measured spot characteristics using grayscale recognition, which involved measuring the quantity of spots (QS), diameter of each spot (DS), average area of each spot (AAES), sum of spot areas (SUSA), sum of shell area (SUSHA), and ratio of SUSA to SUSHA (RSS) on the eggshell. Furthermore, the L, A, and B values of each egg at the sharp, middle, and blunt ends were separately measured using a colorimeter. As a result, average values of 31.31, 29.78, 29.81, and 9.08% of all eggs were divided into score levels 1, 2, 3, and 4 (from opaque to translucent), which correspond with RSS values of 1.34, 3.23, 6.21, and 11.89%, respectively. By grayscale recognition, QS, DS, AAES, SUSA, SUSHA, and RSS all increased along with increased translucency scores (P < 0.05). Using scoring, an egg with a specific RSS value was more easily assigned to a specific score level (50%) or adjacent score levels (50%). The L, A, and B values of eggshells in score level 1 were significantly different from those of eggshells in levels 3 or 4; however, there were no significant differences between any adjacent score levels. In summary, the present study explored objective reference metrics to measure eggshell translucency.

The paper presents findings about how the substitution of calcium, iron, zinc, and copper salts with glycine chelates affects specific reproductive parameters of pheasants, the hatching potential and nutritional components of pheasant eggs, and the fatty acid profiles and cholesterol content in pheasant yolk. 4 groups were created for the experiment: the control, in which the birds received a feed containing standard calcium, iron, zinc, and copper salts, and 3 experimental groups in which chelates were used to replace 25, 50, and 75% of the mineral salts. The group with the 75% chelate share was not supplemented with the salts, and cholecalciferol was replaced with calcitriol. The groups included pheasant females (7 birds) and 1 male, respectively, and were maintained in outdoor aviaries. The birds were administered granulated feed mixes ad libitum, with free access to water. Their feed intake was recorded each day. The birds were weighed at the beginning and end of the egg-laying period. The eggs were collected throughout the egg-laying period, and the eggs gathered at the culmination of the egg-laying period were used for hatching. The eggs were morphometrically analyzed and the hatching process and subsequent hatchling survival rates were investigated. Nutritional components in the eggs were determined, and the fatty acid profiles and cholesterol content were assayed in the yolk. The results showed the use of Ca, Fe, Zn, and Cu chelates in place of salts in the pheasant brood hen diet had contributed to enhancing the egg-laying performance, with a concurrent fall in the size and weight of the eggs. The highest egg-laying performance, with the lowest egg weight, was observed in the group that consumed the highest (75%) share of mineral chelates and received calcitriol supplementation. This corresponded with the highest incubation yield and hatchling survival. The thickest shells and highest crude ash percentages were identified in the eggs of the pheasant group that received a 50% by 50% proportion of salts and glycine chelates. In comparison with the control birds that received the mineral salts, the yolk of the pheasants that consumed the feed with the 75% share of calcitriol and Ca, Fe, Zn, and Cu chelates had a higher percentage of n-6 and n-3 polyunsaturated fatty acids (PUFAs), with a far more advantageous n-6/n-3 proportion. No differences related to the source and levels of Ca, Fe, Zn, and Cu in the feed were observed in the cholesterol content of the pheasant yolk.

The paper aimed to study the effects of lighting pattern and photoperiod alone and in combination on egg production, egg quality in Beijing You Chicken (BYC). A total of 630 19-wk-old BYC laying hens were randomly allocated to 6 groups with 105 birds each, 3 replicates per group, reared in individually lit floor pens with separate outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16, 14, 12 h) was arranged, including 16L:8D (6:00 to 22:00) for group 1; 12L:2D:4L:6D (6:00 to 18:00, 20:00 to 24:00) for group 2; 14L:10D (6:00 to 20:00) for group 3; 10L:2D:4L:8D (6:00 to 16:00, 18:00 to 22:00) for group 4; 12L:12D (6:00 to 18:00) for group 5, and 8L:4D:4L:8D (6:00 to 14:00, 18:00 to 22:00) for group 6, respectively. Egg production parameters were calculated for 22 to 43, 44 to 57, and 22 to 57 wk, and egg quality parameters were measured at the end of 37 and 57 wk. The results showed that the egg production of BYC was not significantly affected by lighting pattern, photoperiod alone, or in combination during 22 to 43 and 22 to 57 wk (P0.05), but average feed intake in 12 h groups was significantly higher than those in 14 and 16 h groups during 22 to 43 and 22 to 57 wk (P0.05). Egg mass and feed egg ratio were significantly affected by lighting pattern, photoperiod alone, and in combination during 44 to 57 wk (P0.05). Egg mass was significantly higher (P = 0.05) and feed egg ratio was significantly lower (P = 0.03) in continuous groups than in intermittent groups. There were significant effects for eggshell thickness, albumen height, haugh unit, and egg grade by lighting pattern alone (P0.05) at 37 wk. The study suggested that 1) the egg production was not significantly affected by lighting pattern alone during 22 to 57 wk (P0.05), but the photoperiod significantly affected average feed intake (P0.05); 2) continuous lighting is better for the egg production during 44 to 57 wk, and intermittent lighting is better for egg quality of the native bird at 37 wk; 3) 12 h lighting is enough for meeting the requirement of the native chicken during the laying period; (4) no change in photoperiod from the rearing to the production phase (12 to 12 L) will have long-lasting effects on egg production or egg quality under the present condition.

The existing literature is inconsistent with respect to optimal dietary concentrations of glycine (Gly) and serine (Ser) in broiler feed. Therefore, we conducted a meta-analysis to investigate the response of broilers to dietary levels of Gly using a full quadratic model based on mixed model methodology. Response was measured as ADG (g/d), ADFI (g/d), and G:F (g/g). In addition, the influence of other dietary constituents was evaluated. This meta-analysis was based on a data set comprising a total of 9,626 broilers in 10 peer-reviewed papers that investigated the response of broilers to different dietary concentrations of Gly, achieved by addition of free Gly. The fitted quadratic model, with either Gly+Ser or the calculated glycine equivalent (Glyequi) of both amino acids as the independent variable, revealed that all model terms were significant (P ≤ 0.05), and hence proved a curvilinear relationship between these independent variables and response traits. The R(2) value and root MS error confirmed a strong relationship between observed and predicted traits. A comparison of the influence of Gly+Ser and Glyequi on response traits revealed that both approaches produced similar results. Because Glyequi should meet the physiological values of a diet better than Gly+Ser, models with 2 independent variables were conducted using Glyequi. The second independent variables were methionine (Met):TSAA ratio and the concentrations of cysteine (Cys) and CP. In models with one or 2 independent variables, the impact of dietary Gly on ADFI was low. By contrast, G:F was markedly influenced by dietary Gly; this effect intensified at lower Met:TSAA ratios and higher Cys and CP levels. ADG was also a function of Glyequi and the second independent variables. For ADG, an optimal Met:TSAA ratio of 0.655 and Cys concentration of 0.302% was calculated. Following the nonlinear nature of relationship, generally applicable replacement values could not be calculated. However, it was concluded that consideration of dietary Cys can diminish the requirement for Glyequi, and therefore, enable a reduction in the CP of broiler diets without limiting growth performance.

In a companion study, the effects of dietary antibiotic alternative and coccidial vaccination on the growth performance of male broilers have been reported. In this paper, the effects of dietary probiotics and coccidial vaccination on diversity and composition of cecal microbiota were investigated using a 3 (diets) × 2 (vaccinated or non-vaccinated) factorial setting of treatments. Three diets, including a corn and soybean-meal control diet, an antibiotic diet (a control diet supplemented with bacitracin and salinomycin), and a probiotic diet (a control diet supplemented with Bacillus subtilis) were provided to broiler chicken from day 0 to 42. To simulate an Eimeria challenge in the field, all chicks were gavaged with a 20× dose of commercial coccidial vaccine containing live Eimeria oocysts on day 14. Cecal contents were collected on day 42. High-throughput sequencing of the 16S rRNA gene was used to determine microbial diversity and composition. Coccidial vaccination to broilers reduced bacterial diversity (Shannon index) of the cecal microbiota. There was a significant interaction between the dietary additive and coccidial vaccination on the observed bacterial species number. Diets supplemented with B. subtilis increased bacterial species of non-vaccinated broilers but decreased bacterial species of vaccinated broilers. In contrast, diets supplemented with antibiotics reduced bacterial species of broilers from both groups. Interactions between dietary additive and coccidial vaccination were also observed on microbial composition. Vaccinated broilers fed the B. subtilis diet exhibited the lowest Firmicutes percentage and highest Bacteroidetes percentage within the microbial community. In addition, vaccinated broilers fed the B. subtilis diet exhibited the highest Rikenella microfusus percentage. From this study, the coccidial vaccination on the day of hatch reduced the microbial diversity of broilers at a later age. The inclusion of B. subtilis-probiotics in the feed of vaccinated broilers may reduce microbial diversity in cecal content by increasing the proportion of a predominant bacterial species, R. microfusus, in the microbial community.

This paper aimed to study the dietary effects of Bacillus subtilis fmbj (BS fmbj) on growth performance, small intestinal histomorphology, and its antioxidant capacity of broilers at 21 d of raising. A total of 300 1-d old male Arbor Acres broilers were randomly assigned to 5 groups: broilers fed the basal diets with 0 g/kg BS fmbj (CON), 0.2 g/kg BS fmbj (BS-1), 0.3 g/kg BS fmbj (BS-2), 0.4 g/kg BS fmbj (BS-3), and 0.5 g/kg BS fmbj (BS-4). The results showed that there were no differences in the growth performance among treatments during the trail. Dietary BS fmbj in broiler diets increased (P < 0.05) the serum immunoglobulin A (IgA) and immunoglobulin G (IgG) concentration, and enhanced the secretory immunoglobulin A (sIgA) level of small intestine (jejunum and ileum) compared with those in the CON group. The BS groups could improve (P < 0.05) the values of villus length, villus width, crypt depth, and villus area of small intestine compared with that in the CON group. Compared with the CON group, the BS group increased (P < 0.05) small intestinal antioxidant capacity and its mitochondrial antioxidant capacity, and also improved the antioxidant related-gene expression. The BS group exerted a lower (P < 0.05) level of oxidative damages in small intestine than that of the CON group. In conclusion, dietary BS fmbj in broiler diets was potential to improve the small intestinal histomorphology, small intestinal antioxidant capacity, and its mitochondrial antioxidant capacity. Thus this BS fmbj might be considered to be an important additive for the poultry industry.

The intestinal gut health is one of the primary determinants of broiler growth and performance. Among the various enteric diseases, necrotic enteritis (NE) is an enterotoxemic disease caused by Clostridium perfringens, which can result in severe economic losses in poultry farming. Antibiotics like bacitracin methylene disalicylate (BMD) and avilamycin (AVL) are commonly used antibiotic growth promoters (AGP) in poultry feed to control necrotic enteritis in birds. Bacillus subtilis PB6 was reported to prevent necrotic enteritis and improve performance in birds. This paper investigated the influence of Bacillus subtilis PB6 in improving the performance of broiler birds in comparison with BMD and avilamycin. A 35 day trial was conducted with 240 day-old commercial broiler chicks (VenCobb 400), which were divided into four treatment groups, where each treatment group was composed of 6 replicates each containing 10 birds, for a total of 60 birds per treatment. The treatment groups included a negative control (no AGP), Bacillus subtilis PB6, BMD, and avilamycin. The parameters analyzed included body weight, feed conversion ratio (FCR), mortality, villus histomorphometry, and European efficiency factor (EEF). Bacillus subtilis PB6 significantly (P < 0.05) improved body weight and FCR (8 points) compared to the control. The group supplemented with B. subtilis PB6 or BMD had higher (P < 0.05) body weight compared to all other treatment groups. The supplementation of B. subtilis PB6 significantly improved the villus height (P < 0.05) compared to control and other AGP groups. The EEF was found to be the highest in the B. subtilis PB6 supplemented group at 35th day as compared to other treatment groups. The combined data from this study indicate that supplementation of B. subtilis PB6 improves overall performance of broilers compared to BMD and avilamycin, and can be used as potential AGP replacement in poultry farming.

The University of Georgia maintains two meat-type chicken control strains: the Athens Random Bred (ARB) and the Athens Canadian Random Bred (ACRB). The Athens Random Bred was developed from colored plumage commercial meat chicken strains in 1956. The ACRB is a replicate population of the Ottawa Meat Control strain which was developed in 1955 from white plumage commercial meat-type chickens. These genetic lines have been extremely valuable research resources and have been used extensively to provide comparative context to modern meat-type strains. The ACRB may be the oldest pedigreed control commercial meat-type chicken still in existence today. This paper reviews the history of the breed backgrounds for both control populations and reviews research utilizing the ACRB.

To comprehensively assess conventional vs. some alternative laying-hen housing systems under U.S. production conditions, a multi-institute and multi-disciplinary project, known as the Coalition for Sustainable Egg Supply (CSES) study, was carried out at a commercial egg production farm in the Midwestern United States over two single-cycle production flocks. The housing systems studied include a conventional cage house (200,000 hen capacity), an aviary house (50,000 hen capacity), and an enriched colony house (50,000 hen capacity). As an integral part of the CSES project, continual environmental monitoring over a 27-month period described in this paper quantifies indoor gaseous and particulate matter concentrations, thermal environment, and building ventilation rate of each house. Results showed that similar indoor thermal environments in all three houses were maintained through ventilation management and environmental control. Gaseous and particulate matter concentrations of the enriched colony house were comparable with those of the conventional cage house. In comparison, the aviary house had poorer indoor air quality, especially in wintertime, resulting from the presence of floor litter (higher ammonia levels) and hens' activities (higher particulate matter levels) in it. Specifically, daily mean indoor ammonia concentrations had the 95% confidence interval values of 3.8 to 4.2 (overall mean of 4.0) ppm for the conventional cage house; 6.2 to 7.2 (overall mean of 6.7) ppm for the aviary house; and 2.7 to 3.0 (overall mean of 2.8) ppm for the enriched colony house. The 95% confidence interval (overall mean) values of daily mean indoor carbon dioxide concentrations were 1997 to 2170 (2083) ppm for the conventional cage house, 2367 to 2582 (2475) ppm for the aviary house, and 2124 to 2309 (2216) ppm for the enriched colony house. Daily mean indoor methane concentrations were similar for all three houses, with 95% confidence interval values of 11.1 to 11.9 (overall mean of 11.5) ppm. The 95% confidence interval values (overall mean) of daily mean PM10 and PM2.5 concentrations, in mg/m3, were, respectively, 0.57 to 0.61 (0.59) and 0.033 to 0.037 (0.035) for the conventional cage house, 3.61 to 4.29 (3.95) and 0.374 to 0.446 (0.410) for the aviary house, and 0.42 to 0.46 (0.44) and 0.054 to 0.059 (0.056) for the enriched colony house. Investigation of mitigation practices to improve indoor air quality of the litter-floor aviary housing system is warranted.