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

Free-range egg production is rapidly growing in Australia with an estimated retail value market share of 48% (AECL, 2014). Laying hens exposed to pasture range may experience reduced performance, poor enteric health and increased mortality (Ruhnke et al., 2014). In addition, egg quality can also be affected, indicated by the increased number of damaged and misplaced eggs as well as decreased egg shell quality (Kijlstra et al., 2009). These effects may be related to excessive fiber digestion and reduced nutrient uptake. The addition of multi-enzymes or organic acids to free-range layer diets may improve the digestion of nutrients, thus increasing performance, gut health and egg quality. A study was conducted to investigate the effect of range types and feed additives on performance and egg quality of ranging laying hens.

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

Free-range layers currently supply ~45% of the Australian egg market. The aim of this study was to investigate feed management practices of free-range layer farms in Australia. An on-line survey was created and promoted from May - Nov 2014. A total of 41 free-range egg producers completed the survey, representing ~10% of the overall Australian commercial egg producers. While 80% of farmers offer a complete diet, 12.5% of farmers conduct combined feeding, and 7.5% choice feeding. Additional feed supplements included shell grit (42.9%), limestone (40.0%), hay (28.6%), silage (8.6%), and others such as vegetables, pasture, insects, and harvested grass (37.1%). Feed was provided as mash (30.0%), pelleted feed (17.5%), whole grains (15.0%), coarse ground (25.0%), and/or fine ground feed (17.5%). Farmers obtained feed from milling facilities (72.5%), produced their own (22.5%), or combined both sources (5%). Hens were fed ad libitum in 77.5% cases. Feed was provided by (gravity refilling) troughs (55.3%), automatic feeder pans (28.9%), or automatic feeder chains (15.8%). Feeders were located in the barn (52.5%), on the range (32.5%), or on both locations (15.0%). With mobile sheds and/or paddock rotation 74.4% of farms had persistent vegetation on the range area and was never stripped bare. Seventy one percent of farmers reported that over 75% of their flock used the range area.

Milling method, thermal treatment, and particle size are important variables determining feed production costs, feed intake and digestibility and potentially egg quality in laying hens. Besides the raw material, the energy needed during production has a major impact on the total feed costs and energy saving milling methods such as the roller mill are becoming more used in the feed industry. Diminution of feed is the largest energy cost in layer feed production (DEATON et al., 1989) and the second largest after pelleting in broiler feed production (REECE et al., 1985). Hammer mills and roller mills are commonly used to reduce particle size of grains (AMERAH et al., 2007; KOCH, 2002). The hammer mill is easier to handle and to maintain, but requires more energy than the roller mill (AMERAH et al., 2007). The hammer mill produces more spherical and uniform shaped particles (REECE et al., 1985), whereas the roller mill generates a more uniform particle size (AMERAH et al., 2007) with irregular cubic or rectangular shape (KOCH, 2002). In addition, hammer mills produce a greater amount of fine particles (REECE et al., 1985). Due to the fact that chickens have a preference for larger feed particles (SCHIFFMAN, 1968), the particle size distribution may affect egg quality, as nutrients may not be equally ingested or effectively utilized (TANG et al., 2006). In contrast, the comparison between corn based diets milled with hammer or roller mills showed no effects on bird performance and egg shell breaking strength (DEATON et al., 1989). Interestingly, layers fed with a barley based diet ground by roller mill had higher egg weight compared to the same diet produced by a hammer mill (HAMILTON, 1994). Layers fed a barley based diet ground by roller mill reduced feed intake and egg production as compared to maize and wheat diets, while no differences were observed when a hammer mill was used. Egg quality was not affected by milling methods (PEREZ-BONILLA et al., 2014).

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

A study was conducted to determine the performance, egg quality, and liver lipid reserves of laying hens exposed to ranges contaminated with Ascaridia galli. Sixteen-week-old Lohmann Brown laying hens (n = 200) were divided into 4 treatments with 5 replicates containing 10 hens per pen. Hens of treatment 1 [negative control (NC)] ranged on a decontaminated area, and hens of treatments 2 (low infection) and 3 (medium infection) ranged on areas previously contaminated by hens artificially infected with 250 and 1,000 embryonated A. galli eggs, respectively. The hens of treatment 4 [positive control (PC)] ranged on areas previously contaminated by hens artificially infected with 2,500 embryonated A. galli eggs, and in addition these hens were orally inoculated with 1,000 embryonated eggs. Results indicated that hens of the medium infection group had a higher number of intestinal A. galli worms and A. galli eggs in the coprodeum excreta (43.9 ± 4.0 and 3,437 ± 459 eggs/g) compared to hens of the low infection group (23.8 ± 4.0 and 1,820 ± 450 eggs/g) (P < 0.01) and similar worm counts to PC hens (34.4 ± 4.0 and 2,918 ± 474) (P > 0.05). Egg production, egg mass, feed intake, and feed conversion ratio (FCR) were not affected by A. galli infection (P > 0.05). Egg quality parameters (egg weight, shell reflectivity, shell weight, shell thickness, shell percentage, shell breaking strength, deformation, albumen height, Haugh unit, and yolk score) were not affected by A. galli infection (P > 0.05). Highly infected hens had lower liver lipid content (2.72 ± 0.51 g) compared to uninfected hens (4.46 ± 0.58 g, P < 0.01). The results indicate that exposure to ranges contaminated with A. galli resulted in infection of the ranging hens, but this did not affect egg production or egg quality. Infection with A. galli lowered the liver lipid reserves of the host significantly, suggesting infected hens use more energy reserves for maintenance and production.

Feed processing including milling techniques and thermal treatments, as well as feed particle size can significantly affect physiological processes in the digestive tract of laying hens and broiler chickens. Additionally, it has been shown that feeding coarse particles alters bacterial colonization in broiler chickens. However, the effect of feed processing on the intestinal bacteria of laying hens has rarely been investigated to date. We hypothesized that bacterial metabolites in the gastrointestinal tract of hens can be affected by feed processing, such as milling method, thermal treatment, and feed particle size.

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

Abatement of odour emissions has become an important consideration to agricultural industries, including poultry production. In order to study the link between diet and odour emissions, an experiment was conducted using twelve Ross 308 broiler chickens. At the age of 22 days, birds of uniform body weight were selected from a total of 288 male birds, adapted to metabolic chambers for six days and fed their respective diets for 15 days. Two treatments were compared using three replicates of two birds per chamber. The two wheat-soy diets were formulated according to the 2007 Ross 308 nutrient specifications for digestible amino acids but they differed in ingredient composition and metabolisable energy content. Thus, Diet A had 13.39 MJ/kg ME and used 60g/kg canola but no corn whereas Diet B contained 12.90 MJ/kg ME and used 150g/kg corn but no canola. The odorous emissions were measured using a Fourier transform infrared spectroscopy. A total of 24 volatile organic compounds were detected and quantified; eight being the major odorous ones: 2,3-butanedione, 2-butanone, dimethyldisulfide, methylmercaptan, 2-butanol, 3-methyl-butanal, phenol and m-cresol. From this pilot study it appears that there is a strong link between diet and odour emissions from broiler chickens.