Tibia Breaking Strength Research Articles

Effect of dietary calcium concentrations in phytase-containing diets on growth performance, bone mineralization, litter quality, and footpad dermatitis score in broiler chickens

This experiment was conducted to investigate the effect of dietary Ca concentrations in phytase-containing diets on growth performance, bone mineralization, litter quality, and footpad dermatitis (FPD) score in broiler chickens. A total of 2100 1-d-old Ross 308 broiler chicks was used and allotted to 1 of 5 dietary treatments with 6 replicates consisting of 70 birds in a completely randomized design. Five commercial-type diets were formulated to contain increasing Ca concentrations of 6.0, 7.0, 8.0, 9.0, or 10.0g/kg. All diets contained 3.5g/kg nonphytate phosphorus and 1000 FTU/kg phytase. Diets were fed to birds for 21 d. At the end of the experiment, birds were sacrificed for tibia sampling and litter samples were collected. The FPD score was measured visually based on a 6-point scale scoring system. Results indicated that increasing Ca concentrations in phytase-containing diets decreased (linear, P<0.01) body weight gain, feed intake, and feed efficiency of broiler chickens. The concentrations of ash, Ca, and P in the tibia, and tibia breaking strength were not affected by dietary Ca concentrations. Dietary Ca concentrations had no effect on litter quality including pH and moisture and nitrogen contents. A tendency (linear, P=0.10) for increased FPD score was observed as dietary Ca concentrations were increased. In conclusion, increasing Ca concentrations from 6.0 to 10.0g/kg in phytase-containing diets have negative effects on growth performance of broiler chickens during 21 d posthatch, possibly due to decreased FI and subsequent phytase intake. Increasing Ca concentrations in phytase-containing diets have little impact on litter quality but tend to increase FPD incidence in broiler chickens.

Performance, intestinal microflora, and amino acid digestibility altered by exogenous enzymes in broilers fed wheat- or sorghum-based diets.

The objective of the current study was to compare the effects of dietary enzymes and nutrient restriction on performance and bone mineralization in birds fed wheat- or sorghum-based diets. A total of 720 d-old male broiler chicks were randomly allocated to 8 treatments, with 6 replicates per treatment and 15 birds per replicate. Birds were reared in floor pens from 0 to 35 d. The study used a 2 × 4 factorial arrangement with 2 grains (sorghum or wheat) and 4 diets: positive control (no enzyme and ME, digestible Lys, Ca, and P sufficient, negative control (NC; no enzyme and reduced ME [-100 kcal/kg], digestible AA [-2%], Ca [-0.12 percentage points], and available P [-0.18 percentage points in the starter phase and -0.22 percentage points in the grower phase]), NC + nonstarch polysaccharide-degrading enzymes + phytase (500 phytase units [FTU]; NCCP), and NC + phytase (1,000 FTU; NCP). From 0 to 35 d, birds fed wheat-based diets had greater G:F (4.5%), BW gain (9.2%), breast meat yield (6.8%), and tibia ash (2.0%) compared with birds fed sorghum-based diets. Across grain types, the NCCP treatment improved BW gain ( < 0.001), feed intake ( < 0.001), G:F ( < 0.05), and livability ( < 0.001) compared with the NC treatment. Birds fed NCP had greater BW gain ( < 0.001), feed intake ( < 0.001), G:F ( < 0.001), and livability ( < 0.001) compared with birds fed NC. Birds fed the NCP diet had greater BW gain ( < 0.001), toe ash ( < 0.01), and tibia ash ( < 0.001) compared with birds fed the NCCP diet. There was a grain × diet interaction for feed intake ( < 0.01), BW gain ( < 0.001), tibia ash ( < 0.01), and tibia breaking strength ( < 0.05). The influence of enzymes was more pronounced in sorghum-based diets than in wheat-based diets. Birds fed wheat-based diets had greater ileal digestibility of His, Met, Val, Phe, Ile, Leu, Trp, Glu, Pro, Ala, Tyr, and Cys compared with those fed sorghum-based diets ( < 0.05). Across grain types, NCP had greater apparent ileal digestibility of Met, Lys, Ser, Pro, Gly, and Cys than NC ( < 0.05). The results suggest that wheat is superior to sorghum for broilers, as expected, but that enzyme supplementation has the capability to restore the compromised bird performance due to feeding sorghum. In addition, compared with nonstarch polysaccharide-degrading enzymes and phytase (500 FTU/kg feed) added in concert, phytase supplemented at 1,000 FTU/kg resulted in a further improvement of some of the performance and bone mineralization parameters in male broilers fed sorghum-based diets.

Performance, intestinal microflora, and amino acid digestibility altered by exogenous enzymes in broilers fed wheat- or sorghum-based diets

The objective of the current study was to compare the effects of dietary enzymes and nutrient restriction on performance and bone mineralization in birds fed wheat- or sorghum-based diets. A total of 720 d-old male broiler chicks were randomly allocated to 8 treatments, with 6 replicates per treatment and 15 birds per replicate. Birds were reared in floor pens from 0 to 35 d. The study used a 2 × 4 factorial arrangement with 2 grains (sorghum or wheat) and 4 diets: positive control (no enzyme and ME, digestible Lys, Ca, and P sufficient, negative control (NC; no enzyme and reduced ME [−100 kcal/kg], digestible AA [−2%], Ca [−0.12 percentage points], and available P [−0.18 percentage points in the starter phase and −0.22 percentage points in the grower phase]), NC + nonstarch polysaccharide–degrading enzymes + phytase (500 phytase units [FTU]; NCCP), and NC + phytase (1,000 FTU; NCP). From 0 to 35 d, birds fed wheat-based diets had greater G:F (4.5%), BW gain (9.2%), breast meat yield (6.8%), and tibia ash (2.0%) compared with birds fed sorghum-based diets. Across grain types, the NCCP treatment improved BW gain (P < 0.001), feed intake (P < 0.001), G:F (P < 0.05), and livability (P < 0.001) compared with the NC treatment. Birds fed NCP had greater BW gain (P < 0.001), feed intake (P < 0.001), G:F (P < 0.001), and livability (P < 0.001) compared with birds fed NC. Birds fed the NCP diet had greater BW gain (P < 0.001), toe ash (P < 0.01), and tibia ash (P < 0.001) compared with birds fed the NCCP diet. There was a grain × diet interaction for feed intake (P < 0.01), BW gain (P < 0.001), tibia ash (P < 0.01), and tibia breaking strength (P < 0.05). The influence of enzymes was more pronounced in sorghum-based diets than in wheat-based diets. Birds fed wheat-based diets had greater ileal digestibility of His, Met, Val, Phe, Ile, Leu, Trp, Glu, Pro, Ala, Tyr, and Cys compared with those fed sorghum-based diets (P < 0.05). Across grain types, NCP had greater apparent ileal digestibility of Met, Lys, Ser, Pro, Gly, and Cys than NC (P < 0.05). The results suggest that wheat is superior to sorghum for broilers, as expected, but that enzyme supplementation has the capability to restore the compromised bird performance due to feeding sorghum. In addition, compared with nonstarch polysaccharide–degrading enzymes and phytase (500 FTU/kg feed) added in concert, phytase supplemented at 1,000 FTU/kg resulted in a further improvement of some of the performance and bone mineralization parameters in male broilers fed sorghum-based diets.

Egg production and welfare of laying hens kept in different housing systems (conventional, enriched cage, and free range)

The aim of this study was to compare egg production performance and welfare traits of laying hens kept in conventional cage (CC), enriched cage (EC), and free range (FR). Lohmann Brown laying hens (n = 480 with 160 per housing type) were studied across a production cycle from placement at 17 wk until depopulation at 66 wk. The hens were randomly allocated into cages or pens of housing system groups; within each system there were four replicates with 40 hens in each pen or cage. The hen day egg production (P = 0.037), feed intake (FI) (P < 0.001), egg mass (EM) (P < 0.001), and dirty egg ratio of hens were higher in the FR system but similar in the CC and EC systems. The highest mortality ratio was found in EC system hens (P = 0.020). The best feather score was found in FR system hens (P < 0.001). The worse body wound score was found in EC system hens (P = 0.038). On the other hand, the worse bumble foot and footpad lesions were found in FR system hens (P < 0.001). The highest tibia breaking strength was found in FR system hens compared with in CC and EC system hens (P < 0.001). The highest Heterophil/Lymphocyte (H/L) ratio was found in CC system hens (P = 0.006) but the blood phosphorus (P) level was higher in FR system hens (P = 0.013). The tonic immobility, blood glucose, total cholesterol, triglyceride, and Ca values of hens were found to be similar in all systems (P > 0.05). The hens in the FR system had additional space for optimum comfort and better feather and bone traits, but the dirty egg ratio, feed consumption, and foot lesions were higher than in CC and EC systems.

Effects of Dietary Calcium Levels on Productive Performance, Eggshell Quality and Overall Calcium Status in Aged Laying Hens.

This study was conducted to investigate the effects of diets with varying levels of calcium on egg production, shell quality and overall calcium status in aged laying hens. A total of five hundred 70-wk-old Hy-Line Brown layers were divided five groups and fed one of the five experimental diets with 3.5%, 3.8%, 4.1%, 4.4%, or 4.7% Ca, for 10 weeks. There were no significant differences in feed intake, egg production and egg weight among groups. The cracked eggs were linearly reduced as dietary Ca levels increased to 4.7% (p<0.01). A significant linear improvement for eggshell strength and thickness were determined with increasing dietary Ca levels (p<0.01). The contents of serum Ca and phosphorus were not affected by dietary Ca levels. With increase in dietary Ca levels, the tibial breaking strength slightly increased. There were no significant differences in the tibial contents of ash, Ca and phosphorus among groups. In conclusion, eggshell quality, as measured by appearance, strength and thickness of eggshell, were influenced by dietary Ca content as expected (p<0.05). These results suggested that aged laying hens require relatively higher level of Ca than required levels from current Korean feeding standards for poultry.

Effects of calcium to non-phytate phosphorus ratio and different sources of vitamin D on growth performance and bone mineralization in broiler chickens

ABSTRACT - A 7 × 2 factorial experiment was designed to test the effects of calcium (Ca) to non-phytate phosphorus (NPP) ratio (1.14, 1.43, 1.71, 2.00, 2.29, 2.57, and 2.86) and different sources of vitamin D (1α-hydroxycholecalciferol (1α-OH-D3) and 25-hydroxycholecalciferol (25-OH-D3)) on growth performance and bone mineralization in 1- to 42-d-old broiler chickens. On the day of hatch, 700 female Ross 308 broilers were weighed and randomly assigned to 14 treatments with five stainless steel cages of 10 birds each. Dietary Ca levels were 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0 g kg−1 and the NPP content was 3.5 g kg−1. The dose of 1α-OH-D3 or 25-OH-D3 was 5 µg kg−1. Diets were not supplemented with cholecalciferol (vitamin D3). Results showed that the Ca to NPP ratio, vitamin D source, and their interaction affected body weight gain (BWG), feed intake (FI), feed efficiency (FE), and carcass and breast yields, as well as tibia weight and length and ash weight in broiler chickens from 1 to 42 d of age. Broilers fed 1α-OH-D3 had higher BWG and FI as well as tibia breaking strength, weight, length, diameter, and ash weight than birds fed 25-OH-D3 at 42 d of age. The Ca to NPP ratio had a quadratic effect on BWG, FI, mortality, as well as tibia breaking strength, weight, length, ash weight, and ash and P contents in 42-d-old broilers. Broiler chickens at 42 d of age obtain optimal growth performance and bone mineralization at the Ca to NPP ratio of 2.32 when 1α-OH-D3 or 25-OH-D3 are used as the vitamin D source.

VITAMIN D3 ALLEVIATES CALCIUM AND PHOSPHORUS DEFICIENCY IN BROILERS

An experiment was carried out to examine effects of using extra dietary vitamin D3 along with low levels of calcium (Ca) and phosphorus (P) on performance, bone quality and mineral retention of broilers. Three starter diets were used; Control (C), Medium (M) and Low (L) which contain Ca: 1.00, 0.75 and 0.50%; non-phytate P (NPP): 0.50, 0.37 and 0.25%; D3: 3,000, 5,000 and 7,000 IU/kg, respectively. As well, three grower diets were used; (C), (M) and (L) contain Ca: 0.90, 0.65, and 0.40%; NPP: 0.45, 0.32 and 0.20%; D3: 3,000, 6,000 and 9,000 IU/kg, respectively. Six treatment groups were distributed according to diets fed in starter and grower periods consecutively; (C/C), (C/M), (C/L), (M/M), (M/L) and (L/L). Each group contained 40 birds in four replicates 10 chicks each. Body weight gain, feed efficiency, plasma concentration of Ca and P and plasma alkaline phosphatase activity, were not affected by dietary treatments compared to (C/C) except for (C/L) group. Similarly, tibia breaking strength, tibia ash and Ca and P percentage, were not affected by different dietary treatments except for (C/L) group which recorded lower bone density compared to (C/C) group. Birds of (C/L), (M/L) or (L/L) groups retained more Ca and P compared with those of other treatments. Based on results obtained, it could be concluded that extra vitamin D3 supplementations (9,000 IU/Kg) to low Ca and NPP (0.40 and 0.20%, respectively) diets could alleviate performance, bone quality and mineral retention, and decrease environmental pollution especially with P, as well as to minimize feed cost.

The impact of feeding supplemental chelated trace minerals on shell quality, tibia breaking strength, and immune response in laying hens

The objective of this study was to investigate the impact of long-term inclusion of the trace elements zinc, copper, and manganese chelated with the hydroxy analogue of methionine on layer performance, eggshell quality, tibia breaking strength, and immune response. A total of 216 Hy-Line W-36 laying hens were allocated to 6 treatments with 36 pens/treatment and 1 hen/cage using a randomized complete block design. There were 6 treatments with supplemental Zn-Cu-Mn, as follows: T1 0-0-0 ppm, T2 20-5-20 ppm as sulfates, T3 20-5-20 ppm as chelates, T4 40-10-40 ppm as sulfates, T5 40-10-40 ppm as chelates, and T6 80-10-80 as sulfates. The feeding of dietary treatments started at wk 24 pullet age and measurements of the key parameters were made from wk 44 to 80. Overall results (one-way ANOVA) indicated a significant treatment effect (P < 0.05) for shell thickness (at wk 74). Hens fed either no supplemental trace minerals (T1) or lower levels of supplemental inorganic trace minerals (ITM) (T2) had lower (P < 0.05) shell thickness when compared to high levels of sulfates (T6). Supplemental minerals as chelates at lower levels (T3) resulted in comparable (P > 0.05) response to T1 and T6 but different (P < 0.05) from T2. Factorial analysis of the data showed an improvement in shell breaking strength (P < 0.05 at wk 68), shell thickness (P = 0.08 at wk 68; P = 0.03 at wk 74), tibia breaking strength (P = 0.07) and antibody (Ab) titers to SRBCs (P < 0.05 at wk 63; 1 wk after secondary antigen challenge) in hens fed chelated trace mineral when compared to inorganic trace minerals. In summary, feeding laying hens’ diets containing supplemental chelated trace minerals showed improvements in eggshell thickness and immune response when compared to inorganic salts at specific time points measured during the latter part of the laying cycle.

Effect of dietary available phosphorus and phytase on production performance of old laying hens and tibia bone quality

Background: Old laying hens are more prone to dietary calcium (Ca) and phosphorus (P) deficiencies as they absorb Ca and P less efficiently than younger hens. OBJECTIVES: In a 2×2 factorial design, the influence of diets with two levels of available phosphorus (AP) and phytase enzyme on the laying performance, egg quality and tibia bone characteristics of laying hens at their late 2nd production phase was studied. METHODS: The experiment used four treatments of 20 Hy-Line W36 hens of 140 weeks old. Treatments 1 and 2 received a 3.5 g kg-1 AP diet while Treatments 3 and 4 received a 2.5 g kg-1 AP diet for 12 weeks. Treatments 2 and 4 received 250 FTU kg-1 phytase in their diet. Laying performance, egg weight, shell weight and shell thickness were measured. On the last day of the experiment, all birds were weighed and blood samples were collected for serum Ca and P measurements. Ten birds from each treatment were sacrificed and both tibiae were excised, defatted, weighed and ashed for Ca and P contents, cortical thickness and bone breaking strength measurements. RESULTS: Hens fed with 2.5 g kg-1 AP diet without enzyme had the lowest body weight gain, serum P, tibia cortical thickness and tibia breaking strength among the treatments (p<0.05). Phytase enhanced body weight gain, egg shell thickness, serum P, tibia weight/body weight and tibia ash/body weight ratios, tibia cortical thickness and breaking strength, particularly in birds receiving 2.5 g kg-1 AP diet (p<0.05). CONCLUSIONS: Phytase may improve bone quality and strength of hens in the late 2nd laying period.

Genetic analysis of bone quality traits and growth in a random mating broiler population

We report the genetic relationship between growth and bone quality traits in a random mating broiler control population. Traits studied were growth rates from week 0 to 4 [body weight gain (BWG) 0 to 4], from week 0 to 6 (BWG 0 to 6), and residual feed intake (RFI) from week 5 to 6 (RFI 5 to 6). Bone quality traits were obtained at 6 weeks of age. These traits were shank weight (SW), shank length (SL), shank diameter (SDIAM), tibia weight (TW), tibia length (TL), and tibia diameter (TDIAM). Likewise, tibia was used to obtain the tibia density (TDEN), tibia breaking strength (TBS), tibia mineral density (TMD), tibia mineral content (TMC), and tibia ash content (TAC). At the phenotypic level, growth traits were positively correlated with most of the bone quality traits except with TDEN and TAC which tended to show unfavorable associations (−0.04 to −0.31). Heritability of bone quality traits ranged from 0.08 to 0.54. The additive genetic associations of growth traits with weight, length, and diameter of shank and tibia were positive (0.37 to 0.80). A similar pattern was observed with TMD and TMC (0.06 to 0.65). In contrast, growth traits showed unfavorable genetic associations with TDEN, TBS, and TAC (−0.03 to −0.18). It was concluded that bone quality traits have an additive genetic background and they can be improved by means of genetic tools. It appears that selection for growth is negatively correlated with some traits involved in the integrity, health, and maturity of leg bones.

Unraveling the associations of osteoprotegerin gene with production traits in a paternal broiler line.

Improvements on growth and carcass traits in the poultry industry have been achieved by intense selection for heavier chickens at early ages. This faster growth has caused serious problems due to insufficient skeletal structure development needed to support the musculature of modern broilers. The osteoprotegerin gene (OPG), located on GGA2, is an important regulator of bone metabolism and reabsorption, being suggestive as a possible functional candidate gene associated with bone integrity in chickens. This study reports associations of a single nucleotide polymorphism (SNP) in the OPG gene with production traits in a parental broiler line. Different phenotypic groups were evaluated: performance, carcass and skeletal traits. SNPs were identified within the OPG gene and the most informative SNP g.9144C > G was chosen for association analyses. Chickens (n = 1230) were genotyped using PCR-RFLP. The association was carried out with QxPaK v4.0 software using a mixed model including sex, hatch and SNP as fixed effects, and the infinitesimal and residual as random effects. The OPG SNP was associated with important traits as body weight at 21 days, weights of tibia and drumstick skin, leg muscle yield, and tibia breaking strength (P < 0.05). Associations were explained by the additive effect of the SNP and the additive effect within sex. This SNP could be considered a potential marker to improve bone resistance in chickens; however, caution should be taken because of its negative effect in other important traits evaluated in this study. Furthermore, these findings suggest a possible involvement of the OPG gene in fat deposition in poultry.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-3-682) contains supplementary material, which is available to authorized users.

Influence of particle size and calcium source on production performance, egg quality, and bone parameters in laying ducks

The influence of calcium source (limestone and oyster shell) and particle size (<0.1 mm; 0.85 to 2 mm) on laying performance, egg quality, and bone properties were examined in laying ducks by a 2 × 2 factorial arrangement of treatments. Longyan females (288) with similar BW at 24 wk of age were randomly allotted into 4 treatments, each with 6 replicates of 12 individually caged birds and studied over the following 12 wk. Particle size affected egg weight and feed conversion (P < 0.05). Large particle size increased shell breaking strength, albumen height, Haugh unit, and shell content of phosphorus and magnesium (P < 0.05), but had no effect on egg shape, yolk color, shell thickness, or the weight proportion of shell. There were no effects of particle size on tibial properties: dry defatted weight, calcium content, or breaking strength. Limestone increased albumen height, shell content of calcium and phosphorus, and the breaking strength of tibia (P < 0.05). It is concluded that limestone with a large particle size provided for superior productive performance, egg quality, and bone characteristics and is more suitable than oyster shell for practical applications.

Effects of Fermentation Product Containing Phytase on Productive Performance, Egg Quality, and Phosphorous Apparent Metabolism of Laying Hens Fed Different Levels of Phosphorus

This study investigated the effects of fermentation product containing phytase (FPP) that was fermented using waste vinegar residue (WVR) as substrate from Aspergillus ficuum NTG-23 on productive performance, egg quality, and phosphorus apparent metabolism of laying hens. First, 375 22-wk-old Jinghong hens were allocated into 5 treatments (5 replicates of 15 hens each) in an 8-wk experiment for evaluating the parameters of productive performance, egg quality, serum, and tibia. Experimental diets contained 4% FPP and 96% corn-soybean diet. The levels of dicalcium phosphate (DCP) were 1.34, 1.01, 0.67, 0.34 and 0%. Next, thirty 31-wk-old Jinghong hens were fed 5 types of diets for evaluating phosphorous apparent metabolism rate. Egg productive rate, egg weight, feed conversion ratio, Haugh unit, egg albumen height, serum calcium, tibia ash, tibia ash calcium and tibia breaking strength were not different significantly among 5 treatments. The significant difference of average daily feed intake was not appeared when the DCP content of corn-soybean-FPP diet was reduced to 0.67%; the eggshell hardness, eggshell thickness and serum phosphorus were not reduced significantly until the DCP content of corn-soybean-FPP diet was reduced to 0.34%. The yolk color was improved when the laying hens fed deficient DCP corn-soybean-FPP diet. A 22.14% reduction in excreta phosphorus was observed when the laying hens fed low phosphorus (0.67% DCP) corn-soybean-FPP diet. A 30% elevation of phosphorus apparent metabolism rate was obtained when the DCP content of corn-soybean-FPP diet was decreased from 1.34 to 1.01%. The reducing cost of layer diet was totalized about 120 CNY 1 000 kg−1 diet when the content of DCP was 0.67% in corn-soybean-FPP diet. These results indicated that FPP could be applied in laying hen as a potential, cost-effective and rational application of WVR.

Efeito da densidade de criação e do grupo genético sobre a composição mineral e desenvolvimento de ossos longos de frangos de corte

The objective of this experiment was to evaluate the mineral composition, volume, bone breaking strenght and optical radiographic density of long bones (humerus, tibia and fêmur) of broiler chickens from three genetic groups and two rearing densities. The experimental design was a splitj-splot where the main plots were a combination of three genetic groups (Isa Label JA57, Ross 308 and Hybro PG) and two rearing densities ( 10 and 16 birds/m2) in a factorial arrangement, and age was considered a secondary plot, so there was six treatments with 5 replications per each treatment, totalizing 30 experimental units. The results founded showed that there were no differences in the studied genetic groups when submitted to two rearing densities for all evaluated parameters, with exception for bone breaking strength of tibia from Isa Label JA57. Bone volume increased with broiler age, while bone breaking strength and bone density showed a decreased from 28 to 35 days of age. Bone mineral content for all treatments showed up growing in the first three weeks, decreasing in the end of the experimental period. The pattern of bone development was the same for all genetic groups, despite the rearing density used, showing that broilers had a standard bone growth curve that is not affected by genetic or rearing density.

Effects of Corn Naturally Contaminated with Aflatoxins on Performance, Calcium and Phosphorus Metabolism, and Bone Mineralization of Broiler Chicks

The objective of this study was to investigate the effects of corn naturally contaminated with low levels of aflatoxins (AF) on performance, calcium (Ca) and phosphorus (P) metabolism, and bone mineralization in broilers. Four hundred and fifty 1-d-old male broiler chicks were randomly allotted to control (no AF), and the diet with the corn contaminated with AF as a substitute for 50% or 100% of the corn in control (HAC or AAC). The broilers in HAC and AAC were administered with 6.5-8.0 and 13.0-16.0 μg AF/kg BW per day respectively in overall period (1-42 d). Ten birds per treatment were selected at d 43 to explore the apparent digestibility of Ca and P using all excreta collection method after 2 days adaptation. The AAC diet reduced (P<0.05) the performance of birds in overall period, whereas the HAC diet temporarily decreased (P<0.05) the performance of birds in starter phase (1-21 d). The corn contaminated with AF had no effect (P>0.24) on the apparent digestibility of Ca and P. The increasing AF intake content linearly increased (P<0.001) serum parathyroid hormone (PTH) level, and decreased (P<0.05) serum 1,25-dihydroxychocalciferol and P concentrations on d 42. On d 21, the AAC diet reduced (P<0.05) tibia breaking strength (TBS) when compared to control or HAC group, however, it did not affect (P>0.10) the percentages of ash, Ca and P in tibia. On d 42, the increasing AF intake level linearly decreased (P<0.05) TBS, and the percentages of Ca and P in tibia. These results indicated that the low level of AF intake had negative effects on the P metabolism and bone mineralization of broilers at exposure of 42 days, which might relate to the changes in vitamin D and PTH metabolism.

The efficacy of a standardised product from dried leaves of Solanum glaucophyllum as source of 1,25-dihydroxycholecalciferol for poultry

1. Chemical characterisation of an extract of Solanum glaucophyllum (SG) leaves affirmed the predominant presence of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) glycosides. The compound 1-(ß-D-glucopyranosyl)-1α,25-dihydroxycholecalciferol was isolated for the first time from a natural source.2. Vitamin D activity of the extract was confirmed by the calcaemic properties shown in a quail eggshell bioassay. The results suggested a 1,25(OH)2D3 bioavailability of approximately 15%.3. A broiler feeding experiment replicated in time was carried out with 6 treatments. A basic control diet containing 25 μg cholecalciferol/kg was supplemented with 2.5 and 5 μg free 1,25(OH)2D3/kg, with a product based on dried SG leaves (Panbonis) providing 10 μg of 1,25(OH)2D3-glycosides/kg, with two concentrations of an SG extract providing 8.8 and 37.8 μg of 1,25(OH)2D3-glycosides/kg.4. Tibia breaking strength and stiffness were numerically greater in all treatment groups with free 1,25(OH)2D3 and with SG products compared to controls, though the overall treatment effects only had probabilities in the range of P = 0.07 to P = 0.1. Values for both characteristics increased progressively, with additions of synthetic 1,25(OH)2D3; values with the dried SG product were similar to those with 5 μg synthetic 1,25(OH)2D3/kg.5. Plasma calcium was mildly elevated (P < 0.05) in treatment groups. The SG extract treatment containing 37.8 μg 1,25(OH)2D3/kg gave the highest plasma calcium concentration and lowest bodyweight, signs of marginal hypervitaminosis D. Plasma 1,25(OH)2D3 concentrations were in the normal range for all treatments.6. Tibial dyschondroplasia occurred in only one replicate. The incidences were 31% in controls but considerably lower or zero with all other treatments.7. Bioavailability of 1,25(OH)2D3 in the SG product seemed to be higher in broiler chickens than in Japanese quails.8. It is concluded that the inclusion of the dried SG product as a source of vitamin D3 in broiler diets at a dietary concentration of 1 g/kg, providing 10 μg 1,25(OH)2D3/kg, is safe and efficacious.

Evaluation of bone strength, keel bone status, plumage condition and egg quality of two layer lines kept in small group housing systems

1. The aim of the present study was to determine the influence of large (54 or 60) and small (36 or 40) group sizes and tiers of the small group housing system “Eurovent German” on tibia and humerus bone breaking strength, keel bone status, plumage condition and egg quality for two commercial layer lines, Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB), at the same stocking density (890 or 830 cm2/bird). 2. In 4 consecutive trials, 4752 hens were recorded for keel bone status. Evaluation of plumage condition was made for 1440 hens and bone breaking strength was recorded for 1200 hens. A total of 4962 eggs were analysed for internal and external egg quality traits. Analyses involved 30 small group compartments per trial. 3. The layer line had a much more pronounced influence on humerus breaking strength than on tibia breaking strength. 4. Plumage condition, particularly on the neck, was positively correlated with humerus breaking strength in both layer lines. 5. An average of 34% of LB and 23% of LSL hens showed keel bone deformities, with higher proportions of slight deformities. 6. Slight keel bone deformities, rather than moderate to severe, increased significantly during the laying period. 7. Stocking density had no influence on bone breaking strength, keel bone status and egg quality traits. 8. LB layers had a 1.4-fold higher humerus, but only a 1.06-fold higher tibia breaking strength compared to LSL layers. 9. Tibia breaking strength was significantly affected by the interaction of group size and layer line. LSL layers in small groups had lower tibia breaking strengths than those of the large groups.

Effect of Layer Breeder Strain and Age on Tibia Bone Characteristics of Chicks

This experiment was designed to study the effect of layer breeder strain and age of chickens on absolute and relative chick weight, tibia bone characteristics, percentage of calcium and phosphorus of tibia bone and body weights. The present results showed that absolute and relative chick weight was highly significantly affected by strain and breeder age. The brown breeder hens produced heavier chick weight compared to the white ones. Tibia bone weight, tibia width, tibia thickness and tibia strength were highly significantly affected by strain, whereas the brown chicks recorded significantly higher values compared to the white ones. Concerning age effect, it could be noticed that all tibia bone characteristics of chicks except tibia breaking strength were highly significantly affected by breeder age, the mid age (at 47 weeks) was characterized with heaviest tibia and longest and thickness. Percentage of calcium in tibia bone did not significantly affected by strain, breeder age and their interaction. Strain had insignificant effect on phosphorus percentage, while breeder age had significant effect of phosphorus percentage. In general, the tibia bone of brown chicks had higher calcium and phosphorus percentages than that of white ones. Chemical analysis decreased as age advanced. Body weight data manifested that brown strain had significantly heavier body weight compared to the white ones. Weight increased gradually as age increased. Corresponding author: mmfathi@fulbrightmail.org

The phytase analytical activity of pelleted diets may not adequately describe efficacy in the bird

SUMMARY Most commercial broilers are fed pelleted diets containing an exogenous phytase. Various techniques exist to prevent denaturation of phytase during pelleting, but the potential remains for phytase to lose efficacy in liberating phytate-bound phosphorus. Dietary treatments consisted of positive control and negative control diets differing in nonphytate phosphorus by 0.13%, as well as the negative control diets containing 1 of 9 Escherichia coli-derived mixer-added heat-stable phytases. Diets were steam conditioned at 71°C (160°F), 77°C (170°F), and 82°C (180°F) before pelleting. Feed samples were analyzed for phytase pre- and postpelleting by a commercial laboratory to determine retained activity. Pellets conditioned at 77°C were chosen for further evaluation via a feeding experiment because all 9 enzymes demonstrated high retained activity in vitro (≥60%). Diets were fed to Cobb 500 male broilers from 3 to 21 d. Feed intake, FCR, BW gain, tibia breaking strength, and tibia bone ash weight per chick were calculated. Seven out of 9 enzymes resulted in BW gain similar to that of the positive control diet. Five of those enzymes resulted in decreased FCR by an average of 8 points compared with the other 2. Tibia measures demonstrated additional differences among enzyme treatments. Phytase activity did not positively correlate with performance or bone mineralization measures. Therefore, evaluations of phytase may need to include in vivo bird testing beyond in vitro activity assays to fully assess efficacy. It is important to note that our conclusions in this study were derived using specific phytase products that were analyzed for activity by using specific protocols, and diets were pelleted within a selected range of processing conditions (i.e., 77°C and 10 s of conditioning); using alternative methodologies may result in different conclusions.

The effects of growth rate on leg morphology and tibia breaking strength, mineral density, mineral content, and bone ash in broilers

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<0.001). Tibia weights (15.36±2.28 g) of FG broilers were also greater than those of SG broilers (11.23±1.81 g; P<0.001). Shank length (81.50±4.71 g) and tibia length (104.34±4.45 mm) of FG broilers were longer than those of SG broilers (71.88±4.66 and 95.98±4.85 mm, respectively; P<0.001). Shank diameter (11.59±1.60 mm) and tibia diameter (8.20±0.62 mm) of FG broilers were wider than those of SG broilers (9.45±1.74, 6.82±0.58 mm, respectively; P<0.001). Tibia breaking strength (28.42±6.37 kg) of FG broilers was higher than those of SG broiler tibia (21.81±5.89 kg; P<0.001). Tibia density and bone mineral content (0.13±0.01 g/cm2 and 1.29±0.23 g, respectively) of FG broilers were higher than those of SG broiler tibia (0.11±0.01 g/cm2 and 0.79±0.1 g; P<0.001). Tibia percentage of ash content (39.76±2.81) of FG broilers was lower than that of SG broilers (39.99±2.67; P=0.173). Fast-growing broiler bones were longer, wider, heavier, stronger, more dense, and contained more ash than SG ones. After all parameters were calculated per unit of final BW at 6 wk, tibia density and bone ash percentage of FG broilers were lower than those of SG broilers.