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The aim of this study was to evaluate the welfare and performance of laying hens kept in a furnished cage system equipped with additional feeders. A total of 72 Lohmann Brown hens were randomly assigned to 4 experimental groups. Each group consisted of 6 cages housing 3 birds per cage (18 birds per group). Group I was a control group without an extra feeder in the cages. Experimental groups GII, GIII, and GIV contained one, 2, and 3 additional feeders in the cages, respectively. The assessment of bird welfare was based on production, physiological and behavioral parameters, as well as on the basis of external appearance. The experiment lasted 12 wk. The obtained results suggest that enriching laying hens' cages with additional feeders improved the welfare of the hens. Enrichment of cages significantly reduced the number of feather pecking and aggressive behaviors in the GII and GIV groups (P < 0.01) and the GIII group (P < 0.05). Breast plumage was significantly (P < 0.05) better in the GII group compared with that in the control group. The control group also had the worst general plumage (P < 0.01). The GII and GIV groups were also characterized by significantly (P < 0.05) lower blood corticosterone concentrations compared with the control group. No negative changes in egg production and quality parameters were observed in the experimental groups. Only eggs from the GIV group had significantly (P < 0.05) lower breaking strength than those from the control and GII group. The results suggest that the best solution is to place 1 additional feeder in furnished laying hens' cages.

The objective of this study was to investigate the effects of dietary iron (Fe) on reproductive performance of Chinese Yellow broiler breeder hens during the egg-laying period. A total of 480, 55-wk-old hens were balanced for laying rate and then randomly allotted into 5 groups, each with 6 replicates (8 cages for each replicate with 2 birds per cage). The trial was for 10 wk. Birds were fed diet with 44, 58, 72, 86, or 100 mg/kg Fe contained feed. Laying performance, biochemical indices and reproductive hormones in plasma, egg quality, ovarian and oviductal variables, tibial breaking strength, and hatching performance were determined. The key performance variables hematocrit, hatchability of live embryos, and tibial breaking strength were selected for analysis by quadratic polynomial (QP) and broken-line (BL) regressions to better determine optimal dietary Fe level. Qualified egg (excluding those with double-yolk, soft-shell, cracked, very small malformed, etc.) rate tended to decrease with the lowest and highest dietary Fe levels. Hematocrit was affected (P = 0.003) by dietary Fe, along with linear (P = 0.017) and quadratic (P = 0.002) effect. There was a significant effect (P = 0.034) of dietary Fe level on tibial breaking strength of breeder hens with a quadratic (P = 0.044) effect. Breeder hens fed inadequate (44 mg/kg diet) or excess (100 mg/kg) Fe both had lower (P < 0.05) tibial breaking strength compared to that of hens fed 86 mg/kg Fe. Hatchability of live embryos was affected (P = 0.004) by diet; with both linear (P = 0.014) and quadratic (P = 0.001) effects. Maximal hatching of live embryos occurred with diets of breeder hens containing 72 mg/kg Fe. From the QP and BL models fitted to hematocrit, tibial breaking strength, and hatchability variables, the optimal dietary Fe level for Chinese Yellow broiler breeder hens in the laying period was 70–90 mg/kg. The daily Fe fed (allowance) was about 8–11 mg.

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

The aim of the current study was to evaluate egg production, quality, and apparent retention (AR) of components in response to a multi-dose application of a single strain Bacillus subtilis (SSB; DSM29784) in a corn-soybean meal basal diet fed to hens (19 to 48 wk of age). The treatments consisted of a basal diet with either no probiotic (control, CON), 1.1E+08 (low, LSSB), 2.2E+08 (medium, MSSB) or 1.1E+09 (high, HSSB) CFU/kg of diet. A total of 336, 19-wk old Shaver White layers were used at a stocking density of 7 and 6 hens/replicate-cage in layer I (week-19 to 28) and layer II (week-29 to 48) phases, respectively. Evaluated variables included feed intake (FI), body weight (BW), feed conversion ratio (FCR), egg production, weight, mass, and egg quality (shell thickness, shell breaking strength, albumen height (AH), and Haugh unit (HU)). Excreta was collected at the end of week-28 for AR of components and apparent metabolizable energy (AME). Supplementation of SSB increased (P = 0.008) FI during peak egg-lay (week-24) and BW increased linearly (P = 0.019) in early layer II (week-32). In layer I, LSSB compared with CON increased EM (g/egg) by 3.3% (P = 0.049). In layer II, SSB inclusion tended to improve FCR (linear, P = 0.094; g FI: g EM). Although shell breaking strength was lowest at week-20 with HSSB (4.518 vs. 4.889 kgf for HSSB vs. CON; P = 0.045), AH and HU were improved at higher dose of SSB, in both phases (P ≤ 0.005). Apparent retention of dry matter, AME, and minerals were improved (P < 0.0001) in a dose response. Hence, while the low dose of B. subtilis DSM29784 improved hen performance and maintained egg quality in both phases, a higher dose of SSB improved the interior protein quality of eggs (AH and HU).

To study the effects of pre-lay dietary Ca and strain on Ca utilization and femur quality at 1st through to 50th egg, 30 Lohmann Brown (LB) and 30 Lohmann Selected Leghorn-Lite (LSL) pullets (14 weeks of age, woa) reared under same management regimen were used. Six pullets/strain were necropsied for baseline femur samples and the rest (24 pullets/strain) placed in individual cages (65 × 30 × 45 cm3) and fed 1% Ca developer diet for 2 wk. At 16 woa, all pullets were weighed and allocated within strains to pre-lay diets (2.5 vs. 4.0% Ca) effectively creating a 2 × 2 factorial arrangement. The pullets were offered pre-lay diets for 2 wk and switched to 4% Ca diet at 18 woa. The diets contained TiO2 to determine apparent retention (AR) of Ca. The age, BW, and feed intake (FI) at 1st, 25th, and 50th egg were recorded. Excreta samples were taken during pre-lay, at 1st and 25th egg and 4 hens per treatment were necropsied for femur samples at 1st, 25th, and 50th egg. There was no interaction (P > 0.05) between pre-lay Ca and strain on Ca intake, femur mineral density (FMD), mineral content (FMC), breaking strength (FBS), and ash (FA) content at 1st, 25th, and 50th egg. At 1st egg, pre-lay Ca interacted with strain on AR of Ca (P = 0.014) such that LB hens retained more Ca at 2.5 vs. 4.0% Ca or LSL at 2.5% Ca. Pre-lay Ca had no effect (P > 0.05) on FMD, FMC, FBS, and FA at 1st, 25th, and 50th egg lay. Compared with LB hens, LSL hens had higher FMD (0.30 vs. 0.19 g/cm2; P = 0.010) and FA (51.9 vs. 42.5%; P < 0.01) at 1st egg and FBS (259.4 vs. 173.8 N, P < 0.01) at 25th egg. In conclusion, except at 25th egg, pre-lay Ca and strain had independent effect on Ca utilization. Femur attributes to 1st egg suggested innate need for LSL birds to accumulate critical bone mass prior to first oviposition.

Effects of dietary non-phytate phosphorus (nPP) restriction on growth and duodenal type IIb sodium-dependent phosphate cotransporter (NaPi-IIb) genes were observed. A total of 432 one-day old Cobb500 male broiler chickens in 36 cage pens were divided into 6 groups with each group containing 6 pens. Each group was treated with one of the diets containing 0.33, 0.37, 0.41, 0.45, 0.49, and 0.53% of nPP up to 14 D. During 15 to 31 D, birds were treated with one of the diets containing 0.23, 0.27, 0.31, 0.35, 0.39, and 0.43% of nPP. Level of Ca was kept the same across all treatments. Dietary nPP level influenced (P < 0.001) weight gain and feed intake in both growth phases, whereas effect on feed per gain ratio was seen only in the second phase. Toe ash, tibia ash, and tibia breaking strength responded to treatments (P < 0.01) at 14 D. Only tibia ash content was significantly improved (P < 0.001) at 31 D. Growth and bone parameters linearly improved with an increase in dietary nPP content (P < 0.05). Above dietary nPP 0.41% and 0.31% for first phase and second phase, respectively, no significant improvement was seen. Duodenal NaPi-IIb mRNA overexpressed with a decrease in dietary nPP in both phases (P < 0.05). Relative expression of NaPi-IIb in lowest nPP group were 2.2 folds higher in the first phase and 3.6 folds higher in the second phase compared to respective highest nPP groups of each phase. No significant change in NaPi-IIb expression was seen above 0.37% of dietary nPP for 14 D and 0.31% of dietary nPP for 31 D. Dietary requirements of nPP 0.41% for 0 to 14 D and 0.31% for 15 to 31 D were adequate for optimal growth and bone parameters. This study fills the gap in understanding of intestinal NaPi-IIb expression in response to dietary nPP restriction in broilers older than 21 D of age.

Poultry eggs from different species varied significantly, due to their divergent process of evolution. However, the information on egg characteristics has been limited mostly to chicken. The current study compared the egg quality, albumen physical and nutritional property for domesticated chicken, duck, goose, turkey, quail, and pigeon. Egg quality traits among different species differed significantly, such as egg weight (from 11 to 139 g), egg shape (from 1.28 to 1.44), proportion of yolk (from 19.3 to 37.9%), and breaking strength (from 0.91 to 8.04 kg/cm2). For the physical property of albumen gel, pigeon egg was the most special one. The albumen gel of pigeon egg had a transparent appearance (A = 1.23), and it had the highest hardness (121.7 g) and water-holding capacity (96%) but a medium level of total cutting work (440 g⋅s). Hence, it was easy for deformation but was hard to cut off when external force was applied. For nutritional compositions of egg albumen, goose egg had the highest moisture (89.21%) and lowest crude protein (8.5%) contents. Specific to amino acid, glutamic acid was found the most abundant in albumen of all six species. Egg albumen of turkey had the highest quantity of essential amino acids (EAA) and total amino acids (TAA), while duck and goose had relatively higher EAA/TAA ratios. Both PCA and cluster analysis revealed the high similarity of amino acid composition between duck and goose, and among quail, turkey, and chicken. The comparative data will improve the understanding of egg qualities of major poultry species and can be helpful in technological application of egg albumen.

We determine interactive effect of a combined model of housing systems for rearing pullets and raising adult birds on bone quality. The LSL-Lite pullets were reared in either an aviary system (A) or conventional cages (C). At week 16, the birds were transferred either to the same housing type through the adult stage (A-A or C-C, for rearing and adult phase, respectively) or to enriched system (A-E or C-E, respectively). In the rearing stage, C cages housed 16 pullets/cage (week 0 to 6) and 8 pullets/cage (week 6 to 16) with a space allowance of 145 and 290 cm2/pullet, respectively; the rearing aviary housed 756 pullets/enclosure allowing 285 cm2/pullet (week 0 to 6) and 754 cm2/pullet (week 6 to 16). In the adult phase, C cages were 58.4 cm wide × 66.0 cm deep (482 cm2/pullet, 8 pullets/cage). For adult A, a commercial multi-tier aviary provided a space allowance >1000 cm2/hen system with litter area. Enriched system housed 60 birds/cage at 750 cm2/bird with perches, nest, and scratch mat. Bone samples were collected from the adult phase (week 73) and analysed for bone quality indices including bone breaking strength (BBS), total bone weight (TBW), ash content of the medullary (femur and tibia), pneumatic (humerus and keel), and radius bones. The A-A hens had the greatest (P

The present study was carried out to investigate the tibia phosphorus (P) retention and development as well as their correlations and possible mechanisms of broilers at different ages. A total of 320 1-day-old Arbor Acres male broilers were raised in 8 replicate cages of 40 birds per cage, and fed the same corn-soybean diets for 42 d. Plasma and tibia samples of broilers were collected on day 0, 7, 14, 21, 28, 35, or 42. The results showed that the tibia ash P content increased linearly (P = 0.017), and the total P accumulation in tibia ash increased linearly and quadratically (P0.001) with age. The traits of bone development including the tibia bone mineral content (BMC), the tibia bone mineral density (BMD), and the tibia ash content increased linearly and quadratically (P0.001), while the tibia breaking strength increased linearly (P0.001) with age. The tibia bone gal protein (BGP) content decreased linearly (P = 0.011), but neither a linear nor quadratic (P0.15) response was observed for the tibia alkaline phosphatase (ALP) with age. The tibia ash P content was positively correlated with the tibia BMD (r = 0.325, P = 0.014), ash (r = 0.325, P = 0.001), and ALP (r = 0.377, P = 0.004). The total P accumulation in tibia ash also was positively correlated with all of the above traits of bone development (r = 0.437 to 0.976, P0.001); however, it was negatively correlated with the tibia BGP (r = -0.426, P = 0.0014). Additionally, the tibia ALP was positively correlated with the tibia ash (r = 0.369, P0.001), and the tibia BGP was negatively correlated with the tibia BMC (r = -0.453, P0.001), breaking strength (r = -0.384, P0.001), and ash content (r = -0.361, P0.001). The above results indicated that the bone P retention was involved in the bone development of broilers from 1 to 42 d of age possibly via the regulation of the bone ALP and BGP.

The objective of this study was to evaluate the effects of dietary Bacillus subtilis supplementation and calcium (Ca) levels on performance, eggshell quality, intestinal morphology, and relative calbindin-D28k (CALB1) mRNA level of laying hens in the late phase of production. An experiment employing a 2 × 3 factorial arrangement of 3 levels of Ca (3.5, 4.0, and 4.5%) and the absence or presence of B. subtilis was carried out with a total of 576 Hy-Line Brown laying hens aged 72 to 79 wk. Every group had 8 replicates of 12 birds each. The results showed that 4.0 and 4.5% Ca levels improved (P < 0.05) apparent retention and serum Ca content of aged laying hens. Compared with the 3.5% Ca level, the 4.0% Ca level in diets increased (P < 0.05) thickness, eggshell weight, shell ratio, and eggshell Ca content of aged laying hens. Moreover, breaking strength, thickness, eggshell weight, shell ratio, eggshell Ca content, apparent retention of Ca in g/day, apparent retention of Ca in percent, villus height, villus height/crypt depth, serum Ca level, and relative CALB1 mRNA level of aged laying hens were all increased (P < 0.05) by B. subtilis supplementation in diets. The supplemental B. subtilis decreased feed conversion ratio (P = 0.001) significantly. In addition, there was an interaction effect between increased Ca levels from 3.5 to 4.5% and B. subtilis supplementation on crypt depth in the duodenum (P < 0.05). In conclusion, we found that both the increase in dietary Ca level from 3.5 to 4.5% and B. subtilis supplementation could enhance intestinal Ca absorption and improve eggshell quality of laying hens in the late phase of production (72-79 wk of age). Dietary supplementation of B. subtilis accompanying the 4.0% Ca level was appropriate in enhancement of eggshell quality.

The objective of the present study was to determine the effect of monobutyrin supplementation on egg production, biochemical indexes, and gut microbiota of broiler breeders at the late stage of production. A total of 180 healthy Qingyuan partridge broilers were randomly assigned to 2 groups: 1) corn–soybean meal–based diet and 2) basal diet supplemented with 250 mg monobutyrin/kg. Each treatment group had 6 replicates/cages with 15 birds within each replicate. The experiment started at week 33 and lasted for 8 wk. Egg production rate, feed conversion rate, shell breaking strength, and shell thickness were not different between control and treatment groups. Supplementation of monobutyrin increased egg weight and tended to decrease egg breaking rate of Qingyuan partridge chickens. Supplementation of monobutyrin did not affect any of the biochemical indexes except total protein concentration. The 4 antioxidant parameters measured were not affected either. Alpha diversity indexes (Shannon, Simpson, Chao1, Ace, and Good’s Coverage) and composition of cecal microbiota were not affected by monobutyrin supplementation. Overall, supplementation of monobutyrin at 250 mg/kg level improved egg quality, but its effect on cecal microbiota composition was limited.

In order to try to combat the effect of age on eggshell quality in aged laying hens, 5 split-feeding treatments were compared with conventional feeding between 75 and 92 wk of age. In the conventional treatment (T1), the same morning (M) and afternoon (A) diet was fed containing fine (FL) and coarse (CL) limestone at a 50:50 ratio. In the split treatments, the ratio of FL and CL was 50:50 or 30:70, and time of administration (M/A) differed. The following treatments were given: T2 = 50FL-M:50CL-A, T3 = 50CL-M:50FL-A, T4 = 30FL-M:20FL-A+50CL-A, T5 = 30FL-M:70CL-A, and T6 = 0M:30FL-A+70CL-A. A total of 12 individually housed Dekalb white hens was used per treatment. Feed intake, nutrient intake, and laying % was lower in T1 compared to all split treatments (P ≤ 0.001). Due to this low performance in T1, split feeding could not be compared to the conventional system in this trial. By the end of the trial, eggshell quality was improved in T1 as a result of low laying % and more frequent and longer laying pauses. In the split treatments, laying % and feed intake were similar, except in T3 in which a decrease was observed after 81 wk (P ≤ 0.05). Egg weight was higher in T5 and T6 due to higher total and morning protein intake compared to T3 (P ≤ 0.05). Feeding only 50FL-A in T3 not only resulted in lower performance but also in consistently lower shell thickness, indicating a negative effect of suboptimal limestone supplementation. In the split-feeding system, the most optimal combination of morning and afternoon diet was a morning diet with only FL and an afternoon diet with only CL (T2), which both provided ∼50% of the total daily Ca intake. Shell breaking strength and dynamic stiffness could be maintained on this diet between 75 and 92 weeks. Decreasing the amount of Ca in the morning and increasing it in the afternoon did not improve shell quality traits. Bone quality was not affected by limestone particle size or inclusion level in the split-feeding system.

This study was aimed at analyzing bone properties of Lohmann White hens in different commercial housing systems at various points throughout production. Pullets reared in conventional cages (CC) were either continued in CC or moved to enriched colony cages (EN) at 19 weeks. Pullets reared in cage-free aviaries (AV) were moved to AV hen houses. Bone samples were collected from 60 hens at each of 18 and 72 wk and 30 hens at 26 and 56 wk from each housing system. Left tibiae and humeri were broken under uniform bending to analyze mechanical properties. Cortical geometry was analyzed using digital calipers at the fracture site. Contralateral tibiae and humeri were used for measurement of ash percentage. AV pullets' humeri had 41% greater cortical areas, and tibiae had 19% greater cortical areas than the CC pullets (P < 0.05). Average humeri diameter was greater in AV pullets than in CC pullets (P < 0.05), whereas the tibiae outer dimensions were similar. Aviary pullet bones had greater stiffness (31 and 7% greater for tibiae and humeri, respectively) and second moment of inertia (43 and 13% greater for tibiae and humeri, respectively) than CC pullets (P < 0.05). The differences between bones of AV and CC hens persisted throughout the laying cycle. Moving CC pullets to EN resulted in decreased endosteal resorption in humeri, evident by a 7.5% greater cortical area in the EN hens (P < 0.05). Whole-bone breaking strength did not change with age. Stiffness increased with age, while energy to failure decreased in both the tibiae and humeri. These results indicated that tibiae and humeri of laying hens become stiffer but lose toughness and become brittle with age. Furthermore, AV and EN systems can bring positive changes in mechanical and structural properties that are more pronounced in the humerus than the tibia.

Keel bone fractures are a well-known welfare problem in modern commercial laying hen systems. The present study sought to identify genetic variation in relation to keel bone fracture susceptibility of 4 distinct crossbred and one pure line, and by extension, possible breeding traits. Susceptibility to fractures were assessed using an ex vivo impact testing protocol in combination with a study design that minimized environmental variation to focus on genetic differences. The 5 crossbred/pure lines differed in their susceptibility to keel bone fractures with the greatest likelihood of fracture in one of the 3 commercial lines and the lowest susceptibility to fractures in one of the experimental lines. Egg production at the hen-level did not differ between the crossbred/pure lines (P > 0.05), though an increased susceptibility to keel bone fractures was associated with thinner eggshells and reduced egg breaking strength, a pattern consistent among all tested crossbred/pure lines. Our findings suggest an association between egg quality and bone strength which appeared to be independent of crossbred/pure line. The findings indicate the benefit of the impact methodology to identify potential breeding characteristics to reduce incidence of keel fracture as well as the potential relationship with eggshell quality.

Osteoporosis in laying hens has been a production and welfare concern for several decades. The objective of this study was to determine whether differing opportunities for exercise during pullet rearing influences long-term bone quality characteristics in end-of-lay hens. A secondary objective was to assess whether differing opportunities for exercise in adult housing systems alters bone quality characteristics in end-of-lay hens. Four flock replicates of 588 Lohmann Selected Leghorn-Lite pullets were reared in either conventional cages (Conv) or an aviary rearing system (Avi) and placed into conventional cages (CC), 30-bird furnished cages (FC-S), or 60-bird furnished cages (FC-L) for adult housing. Wing and leg bones were collected at the end-of-lay to quantify bone composition and strength using quantitative computed tomography and bone breaking strength (BBS). At the end-of-lay, Avi hens had greater total and cortical cross-sectional area (P < 0.05) for the radius and tibia, greater total bone mineral content of the radius (P < 0.001), and greater tibial cortical bone mineral content (P = 0.029) than the Conv hens; however, total bone mineral density of the radius (P < 0.001) and cortical bone mineral density of the radius and tibia (P < 0.001) were greater in the Conv hens. Hens in the FC-L had greater total bone mineral density for the radius and tibia (P

Increased load-bearing exercise improves bone quality characteristics in a variety of species, including laying hens. Providing increased opportunities for exercise during the pullet rearing phase, a period of substantial musculoskeletal growth, offers a proactive approach to reducing osteoporosis by improving bone composition. The main objective of this study was to determine whether differing opportunities for exercise during rearing influences pullet musculoskeletal characteristics. Two flock replicates of 588 Lohmann Selected Leghorn-Lite pullets were reared in either standard, conventional cages (Conv) or an aviary rearing system (Avi) from day-old chicks until 16 wk of age. The keel bone and the muscles and long bones of the wings and legs were collected at 16 wk to measure muscle growth differences between rearing treatments and quantify bone quality characteristics using quantitative computed tomography (QCT) and bone breaking strength (BBS) assessment. Keel bone characteristics and muscle weights were adjusted for BW and analyses for QCT and BBS included BW as a covariate. At 16 wk of age, rearing system had an effect on the majority of keel bone characteristics (P < 0.05). The length of the keel metasternum, caudal tip cartilage length, and the overall percentage of cartilage present on the keel at 16 wk was greater in the Avi pullets compared to the Conv pullets (P < 0.01). Wing and breast muscle weights of the Avi pullets were greater than the Conv pullets (P < 0.001), but leg muscle weights were greater in the Conv pullets (P = 0.026). Avi pullets had greater total bone density, total cross-sectional area, cortical cross-sectional area, total bone mineral content, and cortical bone mineral content than Conv pullets for the radius, humerus, and tibia (P < 0.001). Avi pullets had greater BBS compared to the Conv pullets for the radius, humerus, and tibia (P < 0.01). Increased opportunities for exercise offered by the aviary rearing system increased muscle and bone growth characteristics in pullets at 16 wk of age.

Different ratios of fine- (FL) and coarse limestone (CL) were compared (50FL:50CL, 30FL:70CL, 0FL:100CL) in conventional (C) and split feeding (S) for their effects on performance, egg quality traits, and bone quality of old, brown laying hens (72 to 83 wk). Each treatment consisted of 42 hens (7 hens × 6 replicates). In the C system diets supplemented with limestone were provided during the whole day, whereas in the S system a morning diet was fed without added limestone, and only the afternoon diet was supplemented with different limestone ratios. Highest laying %, egg mass, and lowest feed conversion were found in the C system with 50FL:50CL and 0FL:100CL and in the S system with 30FL:70CL between 76 and 79 wk (P ≤ 0.001). Reduced cracked egg % was found when 0FL:100CL was supplemented in the C system and 30FL:70CL in the S system between 72 and 83 wk (P ≤ 0.001). Tibia ash content was higher in the S system compared to the C system (P = 0.005); tibia breaking strength, however, did not differ between feeding systems. Egg quality traits were not improved by S feeding. However, at 83 wk, S feeding resulted in higher breaking strength, but lower shell thickness compared to the C system (P = 0.036, P ≤ 0.001, respectively). Therefore, hens in the S feeding system might have been able to form a structurally superior shell compared to the C system. For further investigation, instead of restricting limestone supplementation solely to the afternoon, it might be a better approach to provide FL and CL at a different time of the d in a split feeding system to improve shell quality in old, brown laying hens in an extended production cycle. ispartof: Poultry Science vol:96 issue:6 pages:1659-1671 ispartof: location:England status: published

Este artículo se encuentra disponible en la siguiente URL: https://www.sciencedirect.com/science/article/pii/S0032579120300924?via%3Dihub This experiment studied the effect of broiler breeder nutritional strategies on uniformity, carcass traits, tibia parameters, and behavior during rearing and prebreeder periods (up to 22 wk of age). One-day-old pullets (n 5 384) were randomly assigned to 4 treatments arranged as a 2!2 factorial,with 2 fiber levels (control vs. fibrous diet, 15% diluted in AMEn and nutrient content) and 2 vitaminCfeed inclusions (0 vs. 200 mg/kg).At 6, 15, and 22 wk, blood sampling was carried out (4 birds/replicate) to determine serum alkaline phosphatase (ALP) levels, and behavior was observed by visual scan sampling. At 22 wk, carcass traits, tibia parameters, and intestinal morphology were assessed (2 birds/replicate), and tail- and wing-feather integrity of all birds were scored. Fibrous diet did not modify BW uniformity, mortality, or tibia growth when compared with control diet. Pullets fed the fibrous diet had lower tibia breaking strength, elasticmodulus, and ash content values (P , 0.05). They also had lower ALP serum level at 6 and 22 wk (P , 0.05), their breast muscle was less developed (18.5 vs. 19.8%, P , 0.05), and their abdominal fat deposition was higher (1.14 vs. 0.87%, P , 0.05). At 15 and 22 wk, they performed, on average, 97% less grasping feather pecking and 45% less non–food object pecking behaviors, and their wing-feather score was lower (P , 0.05) at 22 wk. Tail- and wing-feather scores of the control treatments were reduced by vitamin Cinclusion (tail: 0.30 vs. 1.15,P,0.05;wing: 0.98 vs. 1.26, P , 0.05) at 22 wk. In conclusion, fibrous diet improves carcass traits (reduces breast muscle and increases abdominal fat deposition), deteriorates bone mineral deposition and thus skeletal strength, and reduces stereotypic behaviors, improving wing-feather integrity. Vitamin C inclusion improves tail- and wing-feather integrity of lower in feed allowance.

The objective of this experiment was to investigate the effects of various dietary concentrations of vitamin D3 (D3) on pullet and laying hen performance, eggshell quality, bone health, and yolk D3 content from day of hatch until 68 wk of age. Initially, 440 Hy-line W36-day-old chicks were randomly assigned to 5 dietary treatments: 1,681 (control); 8,348; 18,348; 35,014; 68,348 IU D3/kg. At 17 wk of age, pullets were assigned to experimental diets with 12 replicate groups of 6 birds. At 17 wk of age, pullets fed diets containing 8,348 and 35,014 IU D3/kg had an increased bone mineral density in comparison to the control fed birds (P ≤ 0.01). Body weights of pullets fed the diet with 68,348 IU D3/kg were lower than other treatments (P ≤ 0.01). Hen-housed egg production (HHEP) of hens fed the 35,014 IU D3/kg diet was increased in comparison to control-fed hens (P ≤ 0.01), whereas HHEP of those fed 68,348 IU D3/kg diet was reduced in comparison to all other treatments (P ≤ 0.01). Shell breaking strength of eggs from hens fed 8,348, 35,014 and 68,348 IU D3/kg was increased in comparison to eggs from control-fed birds (P ≤ 0.01). Fat-free tibia ash content of hens fed any of the diets supplemented with D3 (8,348 to 68,348 IU D3/kg) was increased in comparison to control-fed hens (P ≤ 0.05). Yolk D3 content increased linearly with dietary D3 and the D3 transfer efficiency for the control, 8,348 IU, 18,348 IU, 35,014 IU, and 68,348 IU D3 treatments were 8.24, 10.29, 11.27, 12.42, and 12.06%, respectively. These data suggest that supplementation of dietary D3 up to 35,014 IU D3/kg feed maintained if not increased laying hen performance and enhanced pullet and laying hen skeletal quality as well as yolk D3 content and eggshell quality. Feeding pullets at a higher level 68,348 IU of D3 resulted in reduced growth and ultimately decreased performance of laying hens.

Reducing the incidence of egg shell breakage is an important selection goal in egg layer hens breeding. Breaking strength provides an indicator of static shell resistance correlated with shell thickness. Acoustic egg tests combine shell's resonance profile with egg mass to calculate dynamic stiffness (KDyn) a quantitative indicator of integral shell resistance, and a novel direct detection of both cracks and micro-cracks (MCr) making it possible for use in selection programs aiming improvement of shell quality. A shell quality bio-complex was defined to improve overall shell quality, including: breaking strength at equator (BSe) and poles (BSp), KDyn, and MCr, on multiple eggs/hen-age. A total of 81,667; 101,113; and 72,462 records from 4 generations of three pure lines were evaluated. Two models were tested in the brown-egg line: I) four-trait linear repeatability model and II) three-trait linear (BS, KDyn)-threshold (MCr) in the three lines. Models were implemented with AIREMLF90 and THRGIBBS1F90. Heritability and repeatability (Model I) estimates were: h2 = 0.14, 0.18, 0.33, and 0.02; r = 0.16, 0.28, 0.43, and 0.03 for BSe, BSp, KDyn, and MCr, respectively. Corresponding values in White Plymouth Rock were h2 = 0.14, 0.17, 0.33, and 0.02; r = 0.21, 0.33, 0.44, and 0.04, and in White Leghorn were h2 = 0.14, 0.23, 0.36, and 0.02; r = 0.24, 0.38, 0.52, and 0.02. Genetic correlations between BSe and BSp were between 0.51 and 0.68. The BS traits were moderately correlated with KDyn (+0.23 to +0.51), and tended to be negatively correlated with MCr. KDyn, and MCr (−0.46 to −0.62). Model II had similar results; except for increased h2 = 0.06 and r = 0.09 for MCr. Results indicate that BSe and BSp are different traits; while incidence of MCr is low in heritable but showed negative genetic correlations with the other traits. This makes MCr unsuitable for direct selection; but favors indirect selection against MCr via BSe, BSp, and KDyn for a holistic selection to improve shell quality, in particular to achieve the ultimate goal, reduction of egg breakage.

The aim of this study was to investigate the effect of keel bone fracture (KBF) severity and healing activity on individual productivity of laying hens. Focal hens (75 Lohmann Selected Leghorn (LSL), 75 Lohmann Brown (LB)) were housed alongside non-focal hens in 10 identical pens containing a commercial aviary system (15 focal hens per pen). Eggs of focal hens were identified by orally administering a dye on 3 consecutive days, resulting in a hen-specific color pattern in the yolk. Eggs were collected at 7 time points (37 to 61 weeks of age; WOA) for 5 d to determine individual laying performance and to assess egg quality. Radiographs were performed to score KBF severity on a continuous scale. Healing activity was scored as inactive, healing, or fresh. Linear mixed effects models were used for statistical analyses. We found an association between KBF severity and reduced egg laying performance with increasing age (P = 0.005). At 37 WOA, egg laying performance was similar across KBF severities, whereas at 61 WOA, performance in hens with the highest observed KBF severity was 16.2% lower than in hens without fractures. Hens with fresh fractures had a lower performance than hens with healing and inactive fractures at 37 WOA but higher performance at 61 WOA (P = 0.02). Egg quality parameters were not affected by fractures but were associated with an age × hybrid interaction (egg mass: P = 0.039, shell breaking strength: P = 0.03, shell width: P = 0.001). In conclusion, hens could maintain high performance irrespective of fracture severity until shortly after peak of lay, but seemed to redirect available resources towards fracture healing if a fresh fracture was present. At the end of lay, the negative effect of KBF fracture severity on individual production amplified indicating that hens were no longer able to cope with the physiological challenge of a fracture.

The present study was conducted to evaluate four commercially available phytase sources supplemented at regular (R) and super-dose (S) levels on live performance, bone mineralization, and apparent ileal digestible energy. Broiler chickens were allocated in stainless steel battery brooders (six birds per cage and eight pen replicates per treatment). A basal diet formulated to contain 0.2% non-phytate phosphorus (NPP) and 0.7% Ca was subdivided to create 11 dietary treatments: (1) basal diet was kept as the negative control (NC); (2) NC + limestone and monoclacium phosphate to create positive controls 1 and 2 formulated to yield 0.3% and 0.4% NPP; (3) NC + phytase A (250 and 1,500 FTU/kg); (4) NC + phytase B (500 and 1,500 FTU/kg); (5) NC + phytase C (500 and 1,000 FTU/kg); (6) NC + phytase D (1,000 and 2,000 FYT/kg). Performance was evaluated on d 7, 14, and 22. Tibia bone ash, tibia breaking strength, bone mineral content, and bone mineral density were evaluated on d 22. Apparent energy digestibility was evaluated on d 24. At d 7, phytases A and C supplemented at S level improved (P < 0.05) body weight and weight gain when compared to the NC. At d 14 and 22, all phytase sources improved (P < 0.05) body weight, weight gain, and bone mineralization when compared to the chicks under the NC diet. Overall, phytase supplementation at S level improved 17% apparent ileal digestibility at 24 d. Throughout the grow out period, phytase super-dose yield (P < 0.05) better performance, bone characteristics, and energy digestibility than the regular dietary level. In conclusion, all phytase sources were able to compensate the phosphorus deficiency and promote performance and bone mineralization. High levels of phytase showed a higher response when compared to the lower levels of supplementation.

This experiment was conducted to investigate the effect of a non-fasting induced molt using cassava meal on the eggshell quality, ultrastructure, and porosity in late-phase (74 wk old) HN Brown laying hens. Hens were randomly assigned to 3 treatments of 90 birds each: 1) Controls with no induced molt (CONT); 2) molted by full feeding with cassava meal for 3 wk (FP3); and 3) molted by full feeding with cassava meal for 4 wk (FP4). Following the treatments, groups 2 and 3 were fed a pullet developer diet for 3 weeks. During the molt period, the birds were exposed to an 8L:16D photoperiod and had access to drinking water at all times. Thereafter, all hens were fed a layer diet (17% CP) and exposed to a 16L:8D photoperiod until the end of the study. Compared to the CONT treatment, significant reductions (P 0.05) in shell weight, thickness, and breaking strength were identified on the sixth d of feeding the molt diet. Significant (P 0.05) improvements in these parameters were observed for the FP3 and FP4 treatments during the post-molt period, with the greater degree in the FP4 treatment. In addition, scanning electron microscopy revealed a smaller size of mammillary knobs accompanied by a higher density of mammillae in eggs taken from the molted treatments. Evidence of type B mammillae was detected in an egg produced by the CONT hens, whereas confluent and cuffing mammillae were observed in an egg taken from the FP4 birds. Reduced pore densities were found in the molted treatments in some periods of the post-molt production as compared to the CONT treatment. It was concluded that feeding the cassava molt diet for 4 wk could be an effective non-fasting molt method for improving eggshell quality, ultrastructure, and porosity in post-molt laying hens.

Selection to reduce susceptibility to Enterococcus faecalis infection in laying hens may contribute to the prevention of amyloid arthropathy since it is mainly induced by this bacterium. Therefore, the aim of the present study was to investigate the possibility to select more laying hens that are resistant against E. faecalis infection through the embryo lethality assay (ELA), which is proposed as an alternative model to replace the adult avian challenge assay. Ten-day-old embryos of 500 Lohmann Brown layers were inoculated into the allantoic cavity with an infectious dose of 2.5 colony-forming units (cfu)/mL of the avian E. faecalis strain K923/96 in 3 ELAs. The embryonic mortality rate (EMR) was determined by candling the eggs daily over a period of 4 d. The average EMR estimated during the 3 ELAs was 50% and the highest EMR occurred 3 to 4 d post inoculation. The estimated heritability for embryonic survivability to the infection was h2 = 0.12–0.14, calculated with the logistic and probit link function, respectively, indicating that the selection of more laying hens that are resistant to E. faecalis infection is feasible. A highly negative genetic correlation was estimated between embryonic survivability and laying performance at the peak of lay (rg = –0.22) and at the end of the production (rg = –0.65), as well as with breaking strength (rg = –0.30 to –0.37). A positive correlation was found between egg weight and the embryonic survivability (rg = +0.16), and no genetic correlation was found with body weight and dynamic stiffness. Therefore, although it was demonstrated that it is possible to breed for E. faecalis resistance, special care should be taken to monitor and to take all traits and their genetic correlations into account in order to achieve a balanced genetic progress. Besides, the ELA does not require that the hens are exposed to pathogens thereby saving labor and cost. Therefore, it could be feasible that ELA be implemented in selection programs.

This study investigated the effect of dietary Mn supplementation on eggshell quality, ultrastructure, glycosaminoglycan (GAG), and uronic acid content, and mRNA and protein expression of Galβ1,3-glucuronosyltransferase (GlcAT-I). A total of 216 layers (Hy-Line Grey) at age of 50 wk were divided into 3 groups. In the first 8 wk of the 12-wk feeding trial, all groups were fed a basal diet that met all layer nutrient requirements except for Mn. In the last 4 wk, each group was fed 1 of 3 diets supplemented with Mn levels at 0, 25, or 100 mg Mn/kg. Dietary Mn deficiency did not affect the egg performance of layers. Dietary Mn supplementation significantly improved the breaking strength, thickness, and fracture toughness of eggshells (P < 0.05). In photographs of eggshell ultrastructure, the size of mammillary cones and cracks in the outer surface were decreased by dietary Mn supplementation. The contents of GAG and uronic acids in eggshell membrane were significantly increased by dietary Mn addition (P < 0.05). This result was further confirmed by increased mRNA expression and protein expression of GlcAT-I when Mn was added to the diet. This study suggests that dietary Mn supplementation can improve eggshell quality by enhancing the GAG and uronic acid synthesis in the eggshell glands, which can affect the ultrastructure of eggshells.

The organic matrix from normal and pimpled calcified chicken eggshells were dissociated into acid-insoluble, water-insoluble, and facultative-soluble (both acid- and water-soluble) components, to understand the influence of shell matrix on eggshell qualities. A linear correlation was shown among these 3 matrix components in normal eggshells but was not observed in pimpled eggshells. In pimpled eggshells, the percentage contents of all 4 groups of matrix (the total matrix, acid-insoluble matrix, water-insoluble matrix, and facultative-soluble matrix) were significantly higher than that in normal eggshells. The amounts of both total matrix and acid-insoluble matrix in individual pimpled calcified shells were high, even though their weight was much lower than a normal eggshell. In both normal and pimpled eggshells, the calcified eggshell weight and shell thickness significantly and positively correlated with the amounts of all 4 groups of matrix in an individual calcified shell. In normal eggshells, the calcified shell thickness and shell breaking strength showed no significant correlations with the percentage contents of all 4 groups of matrix. In normal eggshells, only the shell membrane weight significantly correlated with the constituent ratios of both acid-insoluble matrix and facultative-soluble matrix in the whole matrix. In pimpled eggshells, 3 variables (calcified shell weight, shell thickness, and breaking strength) were significantly correlated with the constituent proportions of both acid-insoluble matrix and facultative-matrix. This study suggests that mechanical properties of normal eggshells may not linearly depend on the organic matrix content in the calcified eggshells and that pimpled eggshells might result by the disequilibrium enrichment of some proteins with negative effects.

This study evaluated the mechanical and ultrastructural changes during eggshell formation in laying hens by using the optimal levels of organic and inorganic manganese (Mn). A total of 270 62-wk-old Hy-Line Brown laying hens were fed a basal diet containing 25.1 mg Mn per kg feed for 2 wks, after which they were randomly allocated into 3 groups and fed the basal diet (control) or the basal diet supplemented with 120 mg Mn per kg feed from monohydrate Mn sulfate (an inorganic source of Mn), or 80 mg Mn per kg feed from an amino acid-Mn complex (an organic source of Mn) for 12 wks. For each group, 6 replicates of 15 hens were used with one hen per cage. Dietary Mn supplementation significantly increased eggshell-breaking strength and thickness in laying hens (P 0.05). In neither was the elasticity of their eggshell membranes, measured during the nucleation and mammillary knob formation stages, affected by dietary Mn compared with the control (P 0.05), whereas the breaking strength of the eggshells was greater at the linear and terminate deposition stages compared with the control (P 0.05). Dietary Mn supplementation decreased the width of the mammillary knobs and the proportion of mammillary thickness, and increased the proportion of effective thickness of the whole eggshells (P 0.05). Ultrastructural changes during the eggshell formation indicated that dietary Mn supplementation increased the nucleation site and mammillary knob densities, decreased the mammillary thickness, and increased the proportion of effective thickness and total thickness of the eggshells compared with the control (P 0.05). Therefore, dietary Mn supplementation can improve the breaking strength and ultrastructure of the eggshells during their formation, and the mammillary and palisade layers are both crucial structures affected by Mn.

Damaged eggshells result in losses of eggs. Numerous efforts have been carried out to improve eggshell quality, which may lead to increased eggshell thickness. The conventional way of enhancing eggshell strength with thicker eggshell on average may be replaced by a new strategy to improve eggshell uniformity without increasing eggshell thickness. To achieve this, it is necessary to investigate global variation of eggshell thickness. In this study, we used 100 fresh eggs from 52-wk-old layers of a commercial brown-egg variety. To determine the global variation of eggshell thickness, 42 points for each egg along both longitudinal and latitudinal axes were selected to measure thickness using an eggshell thickness gauge. The eggshell thickness from blunt to sharp end varied significantly (P < 0.05). The area surrounding the blunt end was the thinnest (0.341 ± 0.025 mm), whereas the area surrounding the sharp end was the thickest (0.367 ± 0.023 mm). It was found that the thickness of the sharp end was the closest to the average thickness of the whole eggshell and could be considered as a valid measurement of eggshell thickness. A new parameter, eggshell thickness uniformity, was defined as the reciprocal of the coefficient of variation (1/CV) of eggshell thickness from 42 points of each egg and can be used to evaluate the eggshell quality. Eggshell thickness uniformity was positively correlated with breaking strength (r = 0.341; P < 0.01), suggesting that the parameter may be used as a potential selection criterion in breeding program to improve eggshell quality without increasing eggshell thickness.

This study evaluated the effects of different dietary levels and sources of zinc (Zn) on performance and carbonic anhydrase (CA) activity in eggshell formation and quality in aged laying hens. A total of 504 Hy-line Grey layers aged 59 wk were fed a basal diet (Zn, 28.4 mg/kg) for 4 wks, then randomly allocated to 7 groups that were fed a basal diet or a basal diet supplemented with inorganic (ZnSO4·H2O) or organic (amino acid metals, 9.58%) Zn at 35, 70, or 140 mg Zn per kg of feed for 6 weeks. Each group had 6 replicates of 12 hens. Results showed that egg weight decreased linearly with the supplemental level of organic Zn (P

This study was aimed at investigating the bioefficacy of organic compared with inorganic manganese (Mn) for eggshell quality. An amino acid-Mn complex or Mn sulfate monohydrate was used as the organic or inorganic Mn source. A total of six hundred forty-eight 50-wk-old layers (Hy-Line Brown) were divided into 9 groups; each group consisted of 6 replicates with 12 layers each. The feeding trial lasted 12 wk. During the first 4 wk of the feeding trial, the groups were fed a basal diet, which met the nutrient requirements of the layers, except for Mn. During the following 8 wk, 9 levels of Mn (inorganic Mn: 0, 25, 50, 100, and 200 mg/kg; organic Mn: 25, 50, 100, and 200 mg/kg) were used to supplement, respectively, in the basal diet on an equimolar basis. An exponential regression model was applied to calculate the bioefficacy of organic Mn compared with the inorganic Mn. Dietary supplementation with either organic or inorganic Mn did not influence egg production and feed efficiency of (P 0.05), and eggshell quality did not exhibit a significant response to dietary supplementation with Mn sources at 56 and 58 wk (P 0.05). Dietary supplementation with either organic Mn or inorganic Mn significantly enhanced the thickness, breaking strength, and elastic modulus of the eggshells compared with the control group at the end of 62 wk (P 0.05). At the end of 62 wk, the bioefficacy of organic Mn was 357% (shell thickness), 406% (breaking strength), 458% (elastic modulus), and 470% (eggshell Mn), as efficacious as inorganic Mn at equimolar levels. This study suggests that organic Mn enhances eggshell quality in aged laying hens compared with inorganic Mn.

Four experiments (EXP) were conducted to evaluate the effects of virginiamycin (Vm) in diets adequate or reduced in Ca or nonphytate P (nPP) levels on growth performance and bone response variables in chicks. All diets were corn-soybean meal (C-SBM) based, and all treatments were replicated 6 or 8 times with 5 or 6 chicks each. In EXP 1 and 2, the dietary treatments were 1) C-SBM with 1.00% Ca and 0.45% nPP (positive control; PC); 2) C-SBM with 0.80% Ca and 0.45% nPP (0.80Ca); 3) C-SBM with 1.00% Ca and 0.35% nPP (0.35nPP); and 4 to 6) Diets 1 to 3 with 11 (EXP 1) or 22 (EXP 2) ppm of Vm. In EXP 1, daily gain (ADG), feed intake (ADFI), bone breaking strength (BBS), milligrams of ash per gram of Ca intake (ASH/Ca), and BBS per gram of Ca (BBS/Ca) or nPP (BBS/nPP) intake were increased in chicks fed Vm (P < 0.04 to 0.07). Chicks fed the 0.35nPP diet with Vm had increased ADG, ADFI, BBS, milligrams of tibia ash (ASH), BBS/Ca, and BBS/nPP (nPP x Vm, P < 0.03 to 0.10). Chicks fed the 0.80Ca diet with Vm had increased ASH, milligrams of ASH per gram of nPP intake (ASH/ nPP), and ASH/Ca (P < 0.01 to 0.09). Tibia ash, BBS, gain:feed (G:F), BBS/nPP, and ASH/nPP were decreased in chicks fed the 0.80Ca diet (P < 0.01 to 0.07). Bone ash percentage (BAP), BBS, BBS/Ca, ASH, and ASH/Ca were decreased in chicks fed the 0.35nPP diets (P < 0.01); ASH/ nPP was increased (P < 0.01). In EXP 2, BAP, ASH, ASH/ Ca, and ASH/nPP were increased in chicks fed Vm (P < 0.02 to 0.07). Chicks fed the 0.80Ca diet had a decreased ASH/nPP (P < 0.04) but an increased BBS/Ca and ASH/ Ca (P < 0.01 to 0.02). Chicks fed the 0.35nPP diet had decreased ADG, ADFI, G:F, BBS, BAP, ASH, ASH/Ca, and BBS/Ca (P < 0.01 to 0.04), but BBS/nPP and ASH/ nPP were increased (P < 0.01 to 0.04). In EXP 3, the dietary treatments were 1) PC; 2) C-SBM with 0.70% Ca and 0.45% nPP (0.70Ca); 3) C-SBM with 1.00% Ca and 0.25% nPP (0.25nPP); 4 to 6) Diets 1 to 3 with 9 ppm of Vm. The addition of Vm to the 0.25nPP diet decreased BBS (nPP x Vm, P < 0.06), but Vm increased BBS in the 0.70Ca and PC diets (P < 0.02). Chicks fed the 0.25nPP diet had decreased ADG, ADFI, and BBS (P < 0.01), and chicks fed the 0.70Ca diets had reduced ADFI, BBS, and G:F (P < 0.03 to 0.10). In EXP 4, 4 levels of nPP (0.15, 0.25, 0.35, or 0.45%) and 3 levels of Vm supplementation (0, 11, or 22 ppm) in a 4 x 3 factorial arrangement were used. The addition of Vm increased ADG, BBS, ASH, ASH/Ca, and ASH/nPP only in chicks fed diets with 0.35 or 0.45% nPP (nPP x Vm, P < 0.05). Daily gain, ADFI, G:F, BBS, BAP, BBS/Ca, and ASH were increased as nPP levels were increased (P < 0.01), but BBS/nPP and ASH/nPP were decreased (P < 0.01) as nPP levels were increased. The results obtained from these EXP indicate that Vm, regardless of supplementation level, can partially overcome an nPP deficiency when nPP levels are = 0.35%.

Induced molting increases egg quality and egg production and extends the productive life of hens. Molting is accomplished by feed withdrawal, which has received criticism, and alternatives described thus far result in poor postmolt performance. Melengestrol acetate at a dosage of 4 or 8 mg/d, in a balanced diet, leads to reversible regression of the reproductive tract. However, this alternative must also increase egg quality after rest to be considered an adequate method by the industry. Hy-Line W-36 (n = 497) laying hens were assigned randomly to a diet containing 0 mg of melengestrol acetate (MGA; control) throughout the experiment or 4 or 8 mg of MGA/d for 2, 4, or 6 wk. Upon reaching 50 and 70% lay, after MGA removal, eggs were collected for measurements of egg quality, including Haugh units (i.e., internal egg quality), shell thickness, and breaking strength (i.e., external egg quality). Haugh units were greater (P < 0.05) for eggs laid by hens molted with a diet containing 8 mg of MGA for all durations compared with controls. Shell thickness was greater (P < 0.05) when hens were treated with 4 mg of MGA for 6 wk and 8 mg of MGA for 4 and 6 wk compared with control. Egg breaking strength was greater (P < 0.05) than controls for all hens fed MGA, regardless of dosage or duration of feeding. A subset of hens was fed 8 mg of MGA per hen/d for 2 wk, and eggs were collected for 3 wk. Seven days after MGA was removed from the diet, the amount of MGA in the yolk was below the level of detection of the assay, and the concentration found in the eggs at all time points was 3 orders of magnitude below the Food and Drug Administration's tolerance for MGA in edible tissue. When used as an alterative method to induce a rest, MGA leads to an increase in the internal and external egg quality of hens compared with nonmolted hens.

Dual energy x-ray absorptiometry (DEXA) was evaluated for use as a noninvasive tool to monitor skeletal integrity in live laying hens. The objectives of the current study were 1) to validate the use of DEXA in evaluating bone integrity in live birds as compared with excised bones under a normal nutritional regimen as well as in hens fed varying levels of dietary Ca and 2) to correlate densitometric scans with other bone strength criteria and egg traits. Densitometric scans were conducted on the tibia and humerus of live hens at 10-wk intervals from 17 to 67 wk of age. After each scan, bones were excised from euthanized hens to measure breaking strength characteristics and bone ash (experiment 1). Similar measurements were collected at 38, 48, and 58 wk of age from hens fed hypercalcemic (5.4%), control (3.6%), and hypocalcemic (1.8%) diets from 32 to 58 wk of age (experiment 2). The bone mineral density (BMD) and bone mineral content (BMC) between live and excised bone scans were highly correlated (r = 0.85 and 0.92, respectively, P < 0.0001, experiment 1). Densitometric scans of live birds were positively correlated with bone breaking force and bone ash (r = 0.68 and 0.73, respectively, P < 0.001) with little to no correlation with shell traits. In experiment 2, the excised tibial scan had lower BMD and BMC than the live bird (P < 0.01), whereas no difference was detected in densitometric scans of the humerus. The live and excised BMD and BMC of the tibia (r = 0.87 and 0.82, respectively, P < 0.001) and humerus (r = 0.94 and 0.93, respectively, P < 0.001) were highly correlated. Due to the high correlations between live and excised bone scans and the significant correlations of live scans to more traditional invasive bone measurement tests such as bone breaking force and bone ash, we concluded that DEXA is a useful noninvasive tool for evaluating skeletal integrity in live birds.

Egg quality traits are of utmost importance in layer breeding programs due to their effect on profitability in the egg production industry and on the production of quality chicks. Therefore, the aim of this study was to analyze and estimate genetic parameters of different quality traits: egg weight, breaking strength, dynamic stiffness (Kdyn), egg shape index, eggshell thickness, and albumen height. Eggs were obtained from 4 pure lines of birds. Two different tests were performed: a white breeding program, with eggs from a male and female line of a white egg layer program that were analyzed at 67 to 70 wk of age, and a brown breeding program, with eggs from a male and female line of a brown egg layer program that were analyzed at 32 to 36 wk of age. In general, heritabilities were moderate to high for all traits (h² = 0.23 to 0.71). A high genetic correlation was estimated in both tests between breaking strength and Kdyn (rg = +0.40 to +0.61). Shell thickness was also positively correlated with breaking strength (rg = +0.50 to +0.63) and Kdyn (rg = +0.28 to +0.69). These moderate relationships demonstrate that the strength of an egg not only relies on the shell thickness but also on the quality and uniformity of eggshell construction. Dynamic stiffness might be preferred for breeding purposes due to its lower negative genetic correlation with egg weight and its higher heritability (h² = 0.35 to 0.70) compared with breaking strength (h² = 0.23 to 0.35). Breaking strength and Kdyn were positively correlated with shape index, which confirms that round eggs will show higher shell stability. Therefore, it is necessary to monitor egg shape to maintain an optimal form.

Lameness or leg weakness is becoming an important problem in broilers selected for rapid growth, and although the causes are not known, sedentary behavior could be a cause. Two experiments were conducted to study the effects of distance and the presence of ramps between resources (feed and water) on bone and tendon strength, ability to stand, and productive performance. In experiment 1, straight run Ross 708 chicks (n = 1,260) were randomly assigned to 1 of 3 treatments: 1.0, 3.3, or 6.6 m between resources (6 pen replicates/treatment). In experiment 2, Cobb 500 male chicks (n = 864) were randomly assigned to 1 of 4 treatments (2 × 2 factorial, 4 pen replications/treatment) consisting of 2 distances (3 or 8 m) with (WR) or without (NR) a ramp (a triangular prism 31 cm high and 132 cm wide at the base). At d 21, 45, and 56 (experiment 1), or at d 28, 35, 42, and 49 (experiment 2), birds were weighed, killed, and tibias collected to measure breaking strength (BBS), and abdominal fat (AbF) content. At d 49 (experiment 2), calcaneus tendons were also collected to measure breaking strength (TBS). Foot pad lesions and latency to lie (LTL) were determined before killing the birds. In experiment 1, distance did not affect BBS, LTL, foot pad lesions, or BW, but at d 49, birds in the 6.6 m treatment had lower AbF than birds in the other treatments. In experiment 2 at d 49, birds in the 8 m treatment tended to have a higher BBS than birds in the 3 m treatment (P = 0.09), whereas WR birds had lower tendon breaking strength than NR birds (P0.01); however, LTL was highest in 8-m NR birds. Final BW was not affected by distance, but birds in the NR group were heavier than birds in the WR group. Furthermore, AbF was lower in 8 m than in 3 m birds. Our results suggest that longer distances between resources have limited effects on bone strength, but increase the LTL, and may change feeding patterns and carcass characteristics, as evidenced by the lower AbF content. Ramps or inclination affected tendon breaking strength.

Nonenzymatic glycosylation contributes to the formation of crosslinks, which leads to the structural and functional deterioration of tissue protein. The accumulation of these crosslinks in tissue proteins has been implicated in the alteration of biomechanical properties of connective tissues. The objective of this study was to determine whether tendon breaking time (TBT) and tendon breaking strength (TBS) of the flexor perforans et perforatus digiti iii tendon were related to concentrations of pentosidine in tendons (Pt) of broiler breeder hens from 8 to 125 wk of age. In addition, effects of diet restriction (DR) and a crosslinking inhibitor, aminoguanidine (AG) on Pt, TBS, and TBT were determined. Female chicks (n = 450) were randomly assigned to four treatment groups immediately after hatch: ad libitum-fed (AL); diet-restricted (DR; 60% of AL); and AL and DR groups supplemented with 1.35 mg/kg BW per day AG in the feed (AL+AG and DR+AG, respectively). In AL hens, Pt increased with increasing age (P < or = 0.0001). Concurrently, an age-related parallel increase was found for TBS (P < or = 0.0001) and TBT (P < or = 0.0001). Rate of Pt accumulation was lower in DR (P < or = 0.001), TBS (P < or = 0.01), and TBT (P < or = 0.02) hens compared with AL hens. Concentration of Pt in the AL + AG group was lower (P < or = 0.0002) than in the AL group; TBS and TBT (P < or = 0.01) followed a similar pattern. Supplementation of DR with AG did not affect Pt, TBS, or TBT. The age-related increase in Pt and loss of elasticity in the tendon was retarded by diet restriction and AG.

Mince of 98-wk-old spent hens was washed two times with 0.1% NaCl. Portions of unwashed and washed mince were mixed with a cryoprotectant (CP) composed of 4% sucrose, 4% sorbitol, and 0.2% Na-tripolyphosphate and were immediately frozen and stored at −20 C. Mince without CP was run as control. Textural properties of the stored mince and surimi were measured at 1-mo intervals for 6 mo, after being thawed at 4 C overnight, ground with 3% NaCl, and heated at 90 C for 15 min. For freeze-thaw stability study, minces were subjected to six freeze-thaw cycles. Each freeze-thaw cycle was carried out at 1 mo of storage. Textural quality parameters (gel strength, breaking strength, deformation, protein solubility, expressible moisture, cooking yield, folding test, drip-loss, and sensory scores) were decreased in both unwashed and washed mince, mostly during the early stages of storage. Washed mince showed significantly better textural properties than unwashed mince. Washing protected the gel quality of the hen mince from degradation during frozen storage. Cryoprotectants could not protect the gel strength or breaking strength, but deformation was slightly improved. Water-retention properties were protected, and folding test and sensory scores were well preserved in the mince with added CP. Cryoprotectants had a beneficial effect on frozen, stored spent hen surimi to protect the elasticity and cohesiveness of the gel.

An experiment was conducted to determine whether optimizing profits, as well as eggshell and skeletal strength, by manipulation of dietary Ca level has any influence on either egg weight, egg production or feed consumption during the first 12 wk of production (Weeks 20 to 32, Phase 1). Hens were housed at two environmental temperatures (15.6 to 23.3 and 21.1 to 28.9 C) and fed six diets from 20 to 32 wk of age containing 2.5 to 5.0% Ca with increments of 0.5% and with ME levels ranging from 2,719 to 2,950 kcal/kg, respectively. Egg specific gravity, egg production, egg weight, and feed consumption were determined at weekly or biweekly intervals. At 32 wk of age, plasma Ca, bone density, and bone breaking strength were determined. Results indicated that environmental temperature had no influence on egg production but hens housed at the lower environmental temperature had an increase in egg weight, egg specific gravity, and feed consumption. Increasing dietary Ca level increased egg production, egg specific gravity, feed consumption, ionic plasma Ca, bone density, and bone breaking strength and had no adverse effect on egg weight. It was concluded that Hy-Line® W-36 hens could be fed diets containing as much as 5% Ca with no adverse effect on egg production, egg weight, or feed consumption and that Hy-Line® W-36 hens (Phase 1) under conditions described should be fed diets containing a minimum of 4.25% Ca (3.4 to 3.6 g per hen per d) to 4.5% Ca (3.6 to 3.8 g per hen per d). Calcium intake should range from 3.0 g per hen per d at 21 wk of age to 4.2 g per hen per d at 32 wk of age.

A full-cycle laying hen study was conducted to evaluate crab meal (CM) and lobster meal (LM) as feed ingredients for laying hens by assigning four hundred thirty-two 35-wk-old White Leghorns to 1 of 6 diets [control, 2.5% CM, 2.5% LM, 5% CM, 5% LM, and 2.5% CM + 2.5% LM (blend)]. Productive performance and egg parameters were evaluated every 28-d period. Eggs were collected at 67 wk of age from the 5% CM, 5% LM, and blend treatments for analysis of yolk fatty acid composition. At 55 and 67 wk of age, ulnas were collected to determine breaking strength, percent ash, and calcium. Body weights, feed consumption, hen-day production, feed efficiency, and egg quality were not affected (P0.05) by treatment. The L* scores of eggs from 5% CM, 5% LM, and blend were lower (P0.05) than eggs from the control by the end of the second 28-d period. The a* score of the eggs from 5% CM, 5% LM, and blend was higher (P0.05) than the control by the end of the first 28-d period. The content of docosahexaenoic acid (DHA) in egg yolks was different (P0.05) among the control (0.17 g/100 g), 5% CM (0.46 g/100 g), 5% LM (0.32 g/100 g), and blend (0.38 g/100 g) treatments. Treatment did not affect (P0.05) any of the bone parameters measured at 55 and 67 wk of age. CM and LM supported similar egg production, feed efficiency, egg yolk color, adequate bone strength, and the incorporation of DHA into egg yolks.

Fast-growing broilers are especially susceptible to bone abnormalities, causing major problems for broiler producers. The cortical bones of fast-growing broilers are highly porous, which may lead to leg deformities. Leg problems were investigated in 6-wk-old Arkansas randombred broilers. Body weight was measured at hatch and at 6 wk. There were 8 different settings of approximately 450 eggs each. Two subpopulations, slow-growing (SG; bottom quarter, n=511) and fast-growing (FG; top quarter, n=545), were created from a randombred population based on their growth rate from hatch until 6 wk of age. At 6 wk of age, the broilers were processed and chilled at 4°C overnight before deboning. Shank (78.27±8.06 g), drum stick (190.92±16.91 g), and thigh weights (233.88±22.66 g) of FG broilers were higher than those of SG broilers (54.39±6.86, 135.39±15.45, and 168.50±21.13 g, respectivly; P

The aim of this trial was to determine the effect of aerial perches on keel bone injuries and tibia bone characteristics in free-range laying hens. The relationship between keel bone injuries and individual bird parameters, such as weight, girth, wing:girth ratio, feather coverage, and tibia bone characteristics, was also assessed. Five commercial free-range houses, each containing between 7,000 and 8,000 birds, were used. The houses and range areas were divided in half; in half of the house, birds had access to aerial perches (P) and in the other half, they did not (NP). On 13 occasions between 17 and 70 wk of age, 20 birds per treatment were randomly selected from the slatted area and palpated for keel bone injury. At 72 wk of age, 30 birds per treatment in each of 4 houses were selected at random, weighed, and then euthanized. Girth and wing area and feather coverage were measured. The keel and left tibia bones were removed and keel bones were scored for injury. Tibia bones were weighed and diameter, length, breaking strength, and ash content recorded. Results indicated that access to aerial perches did not affect tibia bone measures (P0.05). Average palpated keel bone score increased with age of the hens (P0.001) but was not significantly affected by perch treatment (P0.05). There was a significant interaction between treatment and farm on keel bone injuries measured at dissection (P0.05), with the probability of birds having high keel-damage scores increasing in the perched treatment in some farms but not others. In general, as the keel bone injury score measured at dissection increased, the breaking strength (P0.001) and ash content (P0.05) of the tibia bone decreased. It is suggested that individual variation in bone strength contributes to differences in susceptibility to keel injury. No relationship existed between keel-injury score measured at dissection and individual parameters, such as weight, girth, or wing:girth ratio (P0.05), although feather coverage tended to decline with increasing keel damage (P0.06).

The effects of thyroid suppression induced during the rearing period by providing various dietary thiouracil (TU) regimens on plasma thyroxine (T4) concentrations, growth, and subsequent egg production (EP) and eggshell quality were determined in Single Comb White Leghorn chickens. Thiouracil was provided in the feed at levels of 0, .1, and .2% from 0 to 6 wk of age in Experiment 1, and at levels of 0, .05, and .1% from 6 to 16 wk of age in Experiment 2. In both experiments, T4 concentrations were reduced during TU treatment. However, T4 later became elevated at 12 and 20 wk in both dosage level groups in Experiment 1. Additionally, BW and egg weights were suppressed by both TU treatments, and EP was reduced up to Week 23 in the .1% TU-treated birds and through Week 25 in the .2% TU-treated birds. No effects on EP were noted in Experiment 2, but feed consumption (FC) was reduced during Week 6 in birds fed .05% TU and during Weeks 6, 10, and 19 in birds fed .1% TU. Both liver and thyroid weights were increased in .1% TU-treated birds relative to controls at Week 16. Eggshell quality was affected only in Experiment 2, in which birds given .05% TU had a higher relative conductance, or maximum rate of water loss, at Week 38 than 0 and .1% TU dosage levels, and .1% TU-treated birds had a higher breaking strength than 0 and .05% TU-treated birds at Week 22. Without associated effects on eggshell quality, EP may be altered through prior changes in FC, BW, and T4 concentration by using TU at a dosage appropriate for the type and age of bird.