Search

A total of 1,200 Ross broiler chickens were used in 2 separate feeding studies to explore the effect of myo-inositol (MYO) and phytase on performance and blood biochemistry of broilers fed diets formulated to be either adequate or insufficient in Ca and digestible P (dP). Supplementation of diets that were formulated to be insufficient in Ca and dP with MYO resulted in improved BW gain and feed conversion ratio in both experiments. However, these effects were most pronounced in the finisher phase, and moderate negative effects were observed during the starter period. Supplementation of the diet with microbial phytase improved BW gain and feed conversion ratio to a similar extent as was observed with MYO, and there was a degree of subadditivity between the 2 additives. Blood glucose concentrations were increased by both MYO and phytase, though possibly by different mechanisms, because insulin concentrations were not directly relatable to circulating glucose levels, especially when both MYO and phytase were applied simultaneously. The increase in blood glucose concentrations with MYO and phytase was most pronounced in the diet with a lower Ca and dP concentration. It can be concluded that dietary supplementation with MYO or phytase was effective in improving performance of commercial broiler chickens. However, further work is required to explore complex ontogenetic effects of MYO and possible involvement of both MYO and phytase in Na-dependent transport mechanisms.

Vitamin D is an essential component of vertebrate nutrition, and epidemiological surveys confirm a chronic vitamin D insufficiency in the human population. Eggs are one of the few natural sources rich in vitamin D, containing both vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25(OH)D₃). 25-Hydroxyvitamin D₃ is especially useful because it provides five times the relative biological activity of vitamin D. In order to establish the potential for enrichment of eggs with D₃ and 25(OH)D₃, a total of 162 hens were fed three levels of D₃ in combination with three levels of 25(OH)D₃. Egg yolks were analysed for their D₃ and 25(OH)D₃ contents, and egg production, egg weights and feed efficiencies were recorded.The contents of D₃ and 25(OH)D₃ in egg yolk increased significantly with increasing dietary concentrations. There were no significant differences in egg mass, egg weight or feed efficiency. Depending on the dietary concentrations used, it was possible to produce eggs with between 100 and 500 IU vitamin D, providing scope to meet the recommended daily requirement of vitamin D for children or adults.The addition of higher levels of D₃ and 25(OH)D₃ produced eggs with sufficient vitamin D to meet the recommended daily requirements of adults and children without any detrimental effect on production parameters.

The effect of feeding diets of variable methionine concentration on breast muscle development was assessed in Ross 308 broiler chicks. Four isonitrogenous and isoenergetic starter diets were formulated to contain 7.8, 5.9, 4.6, and 3.4 g methionine/kg diet, and were provided for the first 7 days post-hatch. At 7 days of age all birds were placed on an industry standard starter diet with 5.9 g methionine/kg diet until 14 days, and then provided standard broiler grower (until 28 days) and finisher (until 42 days) diets. Birds were weighed periodically throughout the study and feed intake and feed conversion ratio were determined. Ten birds per treatment were sacrificed and weighed on 0, 1, 4, 7, 14, 21, 28, 35, and 42 days. The pectoralis major (breast muscle) was then removed from the carcass and weighed. Samples of breast muscle were collected for genetic and histological analysis. Expression of the myogenic marker genes, myogenic differentiation factor 1 and myogenin, which regulate satellite cell activity, and the adipogenic marker gene, peroxisome proliferator-activated receptor gamma (PPARγ), was measured. Histological assessment of breast muscle morphology and fat deposition morphology was also performed. No effect of dietary treatment was observed on body or breast muscle weight, feed intake or feed conversion ratio. Marker gene expression was also similar in all treatment groups, except for PPARγ. Significantly higher expression of PPARγ was observed at 0 days in the 5.9 g methionine/kg diet treatment, before dietary treatments were provided. Expression of PPARγ did not differ among treatment groups on any subsequent day. Methionine dietary treatment had no effect on the morphological structure of the breast muscle, or intramuscular fat deposition. These results suggest that under the conditions of this study, satellite cell activity in the early post-hatch chick, and subsequent muscle development, were not responsive to the variable methionine manipulations tested in the pre-starter period.

A total of 640 male Ross 308 broiler chickens were used to explore the interactive effects of diet nutrient density, exogenous protease and ascorbic acid on performance, nutrient digestibility and various gut health metrics. A total of eight dietary treatments were arranged as a 2 × 2 × 2 factorial with the factors being adequate or reduced (~4%) crude protein and amino acids, without or with exogenous protease and without or with supplemental ascorbic acid. Over the 35-day experimental period, birds that received the adequate diet had higher (P < 0.01) bodyweight gain and lower (P < 0.001) feed conversion ratio (FCR) than birds that received the diet with reduced protein and amino acid density. Supplemental protease reduced (P < 0.001) FCR and this influence was more apparent in birds fed the diet with reduced protein concentration. Gut tensile strength tended to be increased by protease (P = 0.09) and ascorbic acid (P = 0.06) supplementation. Supplemental protease reduced (P < 0.001) jejunal goblet cell numbers and epithelial thickness and increased (P < 0.05) villus height compared with unsupplemented diets. Ascorbic acid tended (P = 0.05) to increase sialic acid concentration in ileal digesta. Protease increased (P < 0.01) the coefficients of apparent ileal digestibility for all amino acids other than methionine and this effect tended (P = 0.07 to 0.09) to be more pronounced in the low protein diet for aspartic acid, histidine and arginine. The concentration of taurine in ileal digesta was reduced (P < 0.01) by protease whereas hydroxyproline concentrations tended (P = 0.09) to increase by ascorbic acid addition. These results confirm previous reports on the effectiveness of exogenous protease in diets reduced in crude protein and digestible amino acids. Furthermore, both protease and ascorbic acid may influence gut health through promotion of tensile strength, epithelial morphology and endogenous protein flow. The interaction between exogenous protease and ascorbic acid on gut health with an emphasis on collagen structure and tight junction integrity is an area for future study.

A total of 672 male 7-day-old broiler chicks were used in a 14-day cage study to evaluate the interactive effects of dietary protein source and exogenous protease on nutrient digestibility and intestinal physiology. Birds were fed a common starter diet from Days 0 to 7 and switched to experimental diets from Days 7 to 21. Four corn-based dietary treatments were arranged in a 2 × 2 factorial arrangement with factors being two major sources of protein [soybean meal (SBM) or canola meal] and diets offered with or without exogenous protease. Bodyweight gain and gain:feed were higher (P < 0.001) in the diets based on SBM than in the diets based on canola meal and protease was more effective (P < 0.05) in enhancing performance in SBM-based diets. Ileal nitrogen digestibility was increased (P < 0.01) by protease use in diets based on both major protein sources. However, ileal digestible energy was increased (P < 0.05) by protease only in the SBM-based diet resulting in an interaction between diet protein source and exogenous protease. Jejunal villus height tended to be higher (P = 0.07) in birds fed diets based on SBM and protease use increased (P < 0.05) crypt depth only in the SBM-free diets resulting in a significant interaction between protein source and protease use. Patterns of gene expression in jejunal tissue suggested that both dietary protein source and exogenous protease influence the expression of genes responsible for mucin secretion, amino acid transport and immune functionality in an age-dependent manner. It can be concluded that SBM may be a more suitable protein source for young broiler chickens than canola meal and that use of canola meal as a major source of dietary protein may have negative implications for performance, nitrogen digestibility and gut health. However, exogenous protease appears to be more compatible with substrates presented by SBM than is the case for canola meal based on advantages conferred in nutrient digestibility and performance. The beneficial effects of exogenous protease may be linked both to enhanced protein and energy digestibility and improved gut morphological characteristics, secretory and absorptive dynamics and immune resilience.

High inclusion concentrations of dietary calcium (Ca) from limestone may have detrimental effects on broiler performance, such as increased gastric pH and a reduction in phosphorus (P) and amino acid digestibility. To assess the potential for feeding diets with lower total Ca concentrations, the effect of a novel highly soluble source of calcium (HSC) on bird performance, nutrient digestibility and skeletal integrity of 1120 male Cobb-500 broilers was compared with that of limestone. Eight dietary treatments in a 2 × 2 × 2 factorial design consisted of two sources of Ca (limestone or HSC), two concentrations of Ca (6.0 or 7.7 g/kg in the starter and 4.0 or 5.7 g/kg in the grower), two phytase levels (0 or 500 FTU/kg). The effect of dietary treatments on growth performance and feed intake were measured from Day 1 to Day 40 and foot ash and leg health on Day 40. At the end of the starter period, in the absence of phytase, changing Ca source from limestone to HSC at 6.0 g/kg total Ca decreased both bodyweight gain and feed intake (P < 0.05). The addition of phytase to diets containing 6.0 g/kg total Ca provided by HSC increased bodyweight gain (P < 0.05), as well as increasing feed intake (P < 0.05). At the end of the grower period, diets supplemented with phytase increased bodyweight gain (P < 0.001), birds fed the higher Ca concentration were also observed to have an increased bodyweight gain (P < 0.001). Apparent ileal Ca digestibility significantly increased with the addition of phytase to diets containing 4.0 g/kg total Ca provided by HSC (P < 0.05), this was also observed for P digestibility. Replacement of limestone with HSC when fed in conjunction with phytase has the potential to be an effective strategy to improve broiler performance and bone mineralisation.

A total of 160 Ross PM3 birds were used in a two treatment feeding study in order to explore the usefulness of proteomics to identify the origin of peptides in ileal digesta. Two diets were fed, one conventional maize/soy-based diet acted as a reference whereas a second diet, formulated to be nutritionally equivalent to the reference diet in protein and energy provision, contained 20% raw soy meal in order to (putatively) elicit changes in intestinal protein flow. Each diet was fed to 10 replicate cages of eight birds per cage from Day 1 to 21. Feed and water were available ad libitum and an indigestible marker was included for assessment of ileal digestibility. Weight gain and feed intake were monitored and at the end of the trial period birds were killed, pancreatic mass was measured and the ileum was excised and the contents were collected, immediately frozen in liquid nitrogen and were subsequently lyophilised. Protein from the ileal digesta was extracted and exposed to proteomic analysis with peptide fragments identified and compared with an amalgamated database containing protein sequences from chicken, soy and maize. Addition of 20% raw soy meal to the maize/soy-based diet resulted in a reduction in weight gain, feed intake and an increase in feed conversion ratio (P < 0.001). Pancreatic mass was significantly increased and the apparent ileal digestibility of protein was significantly decreased by raw soy meal inclusion. Overall, a total of 248 proteins were identified from endogenous origin, 336 from soy and 411 from maize. However, the relative abundance of these proteins were ~20–30% for endogenous protein, 65–75% for soy protein and ~2–4% for maize protein. The addition of 20% raw soy meal resulted in an increase in the relative abundance of endogenous protein and a reduction in the relative abundance of protein from soy with no measurable effect on the presence of protein from maize. Specifically, in the endogenous protein fraction, there was a significant reduction in the relative abundance of metalloendopeptidase, aminopeptidase and alkaline phosphatase and a significant increase in the relative abundance of colipase and trypsin, in response to raw soy meal inclusion. For proteins originating from soybean, the addition of raw soy meal to the diet resulted in a significant increase in the relative abundance of protein from the 2S albumin fraction, Kunitz and Bowman–Birk trypsin inhibitors and soybean agglutinin whereas there was a reduction in the relative abundance of globulin and glycinin. Addition of raw soy meal to the diet also resulted in a significant increase in the presence of maize prolamin in the lumen and a significant decrease in the presence of globulin-2, β-1–3-glucanase and cystatin. These results demonstrate considerable potential of proteomics technology to identify changes in the digestion and secretion of protein in the intestine of chickens. Although these data are preliminary and based on an animal model that included diets that were formulated to have a chronic effect on intestinal physiology it is evident that changes in diet composition can have a profound effect on the origin of protein that leaves the ileum.

SummaryVariance in macro- and micro-mineral concentration in feed ingredients for farmed livestock contributes to sub-optimal performance and may compromise health and welfare. Although routine quality assurance and quality control procedures in feed mills or integrated poultry or swine businesses may track variance in the concentration of minerals of immediate nutritional importance, such as phosphorus (P), calcium (Ca) and sodium (Na), micro-minerals such as strontium (Sr) attract less attention. In order to create a framework for further study, the mineral concentration in more than 130 animal feed ingredients commonly used in Australia were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Due to a dearth of information, the principal focus of the survey was Sr, but the concentration of Ca, P, magnesium (Mg), manganese (Mn), potassium (K), iron (Fe), copper (Cu), zinc (Zn), sulphur (S) and Na were analysed concurrently. Generally the minerals present at the highest concentrations in the various feed ingredients examined were Ca, P and Mg. As anticipated, the ingredients with the highest concentrations of Ca and P were inorganic phosphates, limestone and meat and bone meal. The average Ca concentration in limestone was 393 g/kg but a range of 376–415 g/kg was observed which may be nutritionally important. Furthermore, the Mg concentration in limestone ranged from 7–535 mg/kg suggesting some contamination by dolomite lime sources. A total of 24 meat and bone meal samples were included in the analysis and mean Ca and P concentrations were 109 and 54 g/kg respectively. However, the range of Ca and P in meat and bone meal was considerable with Ca concentrations from 51–148 g/kg and P concentrations from 26–66 g/kg. A total of 81 cereal, grain legume and cereal by-product samples were included as part of the survey and these vegetable feed ingredients contained relatively low concentrations of most minerals with Ca, P, Mg and K dominating. The K concentration of soybean meal was found to be around 23 g/kg and ranged from approximately 22–27 g/kg. In comparison, the Sr concentration in the feed ingredients was low relative to other minerals, with limestone having the highest level of strontium at 329 mg/kg. Overall those feed ingredients from a mineral origin had the highest level of Sr. In addition, meat and bone meal had a relatively high concentration of Sr (around 159 mg/kg).

SummaryA meta-analysis of the effect of a mono-component bacterial protease (RONOZYME® ProAct) on the apparent ileal digestibility of amino acids in poultry and swine diets was conducted to examine functional patterns, mean effects and variability of response. A total of 25 independently-conducted experiments were included comprising a total of 804 datapoints. The mean response to protease was +3.74% (SE 1.1%, P 0.05). However, the inherent digestibility of amino acids in the control diet as a single explanatory term explained around 47% of the variance (P

The interaction between sodium phytate and three proteins was studied using solubility experiments and differential scanning calorimetry (DSC) to assess structural stability. Lysozyme, which is positively charged at neutral pH, bound phytate by an electrostatic interaction. There was evidence that phytate cross-linked lysozyme molecules forcing them out of solution. Myoglobin and human serum albumin, which were neutral or negatively charged, respectively, displayed association rather than binding, and there was no complex formation. All of the proteins were structurally destabilized by the presence of phytate but were not denatured. From these findings, we predict that phytate would bind electrostatically to a wide variety of positively charged proteins in the stomach as well as to trypsin and chymotrypsin in the duodenum. Both binding reactions may compromise the digestion of the protein component in feed stuffs. Because the interaction between phytate and protein is electrostatic, the presence of anions, such as chloride, would nullify the antinutritional effect of phytate.

Using layer hens, Gallus gallus domesticus, we compared the digestive capabilities of birds on a low-fibre diet (LF, 8.49% neutral detergent fibre; NDF), with those fed a high-fibre diet balanced for energy and protein to match the LF diet (high fibre balanced, HFB; NDF = 15.61%) and those fed a high fibre unbalanced (HFU) diet (NDF = 16.68%). The HFU diet had the lowest apparent dry matter (DM) metabolisability at 58.14 ± 6.46%, followed by HFB, 65.87 ± 3.50 and the LF diet, 70.49 ± 7.07%. Despite significant differences between apparent DM metabolisabilities of LF and HFU diets, no morphometric changes in the gastrointestinal tract (GIT) of layer hens were observed (including crop, gizzard, proventriculus, liver, large intestine, paired caeca and small intestine). Conversely, body mass losses were recorded for animals on HFU diet, while those on the LF and HFB diets actually gained body mass over the 14-day trials. We suggest that the body mass losses seen in the animals fed HFU diets were attributed to losses in adipose tissue, but this was not quantified. Assuming body mass losses were mainly in adipose tissue, we propose that adipose may act to buffer environmental challenges like shortfalls in nutrient acquisition when dietary energy requirements are not met. Compared with smaller birds (e.g. quail), the larger body size of the layer hens may offer them a greater safety margin in terms of body energy reserves before changes in the GIT might be needed to redress energy deficits associated with hard-to-digest, high-fibre diets.

An experiment was conducted to determine the relationship between in vitro assays to estimate quality and ileal nutrient and energy digestibility of various corn sources. Twelve samples of corn were analyzed for gross energy (GE), N, moisture, crude fat (CF), salt-soluble protein content (SSP), and vitreousness. Six of the 12 sources of corn had similar proximate composition but ranged in pairs as having low, moderate, or high quality based on protein solubility that varied from 25.7 to 49.2%. Experimental diets consisted of corn sources with 0.50% TiO2. In total, 504 (12 per pen; 0.039 m2 per bird) Ross×Ross 708 male broiler chicks were randomly distributed to 42 pens (7 replicates per treatment) at 1 d of age. Broilers were fed common starter and grower diets from 1 to 27 d of age and experimental diets from 28 to 30 d of age. At 30 d of age, 8 birds per cage were euthanized for digesta collection from 4 to 30 cm proximal to the ileocecal junction. Feed and digesta were analyzed for TiO2, GE, N, CF, and starch content. Ileal digestibility of N (apparent), CF, and starch did not differ (P>0.05) among sources of corn. Apparent ileal digestible energy (IDE) of the 6 corns averaged 3,323 kcal/kg. Salt-soluble protein concentration was correlated with IDE among the corns (r=0.5; P

A total of 240 Ross 308 broilers were used to investigate the effect of sodium (1·5 or 2·5 g/kg), phytate-P (0 or 3·2 g/kg), and phytase (0 or 1000 FTU/kg; 2x2x2 factorial) on endogenous amino acid flow using the enzyme-hydrolysed casein method. The ingestion of phytate increased endogenous amino acid flow (∼30%) compared with the phytate-free control diets. Phytase reduced endogenous amino acid flow only when fed in concert with phytate, resulting in a significant phytate x phytase interaction. Increasing dietary sodium concentration from 1·5 to 2·5 g/kg reduced endogenous amino acid flow by around 10%. This reduction of endogenous flow was particularly evident in diets which contained phytate, resulting in a significant sodium x phytate interaction for several amino acids, including Thr and Ser. Further, high sodium concentrations muted the effect of phytase resulting in a significant sodium x phytase interaction for some amino acids. The concentration of Asp, Thr, Ser and some other amino acids was increased in the endogenous protein in response to the ingestion of phytate. Both sodium and phytase essentially restored the composition of endogenous protein to that of the phytate-free control. Further, as both sodium and phytase had similar effects there were significant interactions between sodium and phytase for most amino acids, such that one was only effective in the absence of the other. These data confirm previous reports that phytate is a nutritional aggressor, causing quantitative and qualitative changes in endogenous protein flow. However, this is the first report which has shown that dietary sodium concentrations play a role in the severity of this antinutritional effect and consequently may blunt the efficacy of exogenous phytase. The mechanism is obscure, though it has been previously demonstrated that sodium can disrupt phytate:protein complexes, thus mitigating one of the mechanisms by which phytate exerts its antinutritional effect.

The effect of dietary phytate and phytase on carbohydrase activity and hexose transport was investigated in broiler chickens. Diets containing phytate P (2.2 or 4.4 g/kg) with different phytase dose rates (0, 500, or 1,000 phytase units/kg) were fed to 504 female Cobb chicks for 3 wk. Diets containing high phytate concentrations depressed (P < 0.05) BW and G:F, whereas phytase supplementation improved (P < 0.05) the performance of birds. In the duodenum, phytate decreased (P < 0.05) the activities of disaccharidases, Na + K + -ATPase, and glucose concentrations by 5 to 11%, but phytase enhanced (P < 0.05) the concentrations of amylase, sucrase, maltase, Na + K + -AT-Pase, and glucose by 5 to 30%. In the jejunum, phytate decreased (P < 0.05) the concentrations of amylase, sucrase, Na + K + -ATPase, and glucose by 10 to 22%, and phytase alleviated the negative effect of phytate on the above variables. Ingestion of diets containing phytate also decreased (P < 0.05) serum amylase activity and glucose concentration, and phytase enhanced (P < 0.05) serum concentrations of amylase, sucrase, maltase, Na + K + -ATPase, and glucose. There were also interactions (P < 0.05) between phytate and phytase on the concentrations of serum amylase, duodenal amylase, sucrase, and jejunal glucose. Enzymatic analysis at a molecular level showed that neither phytate nor phytase influenced the mRNA expression of sucrase-isomaltase in the small intestine. Also, the investigation into the sodium glucose cotransporter gene may challenge the mechanism by which phytate interferes with glucose utilization, as partly indicated by bird performance, and transmembrane transport because diets containing increased phytate upregulated (P < 0.05) the mRNA expression of the sodium glucose cotransporter gene in duodenum and did not influence it in the jejunum. These results indicate that phytate can impair endogenous carbohydrase activity and digestive competence, and phytase can ameliorate these effects for chickens.

Summary A study was conducted to investigate the effect of the key cereal grains and a microbial enzyme supplement on broiler chicken performance, gut microflora and intestinal function. Ingestion of the barley-based diet was associated with low 28-day body weight, decreased feed intake and high FCR. The supplemental enzyme increased feed intake and weight gain of the chickens on a wheat-based diet. The pH of the gizzard and caecal contents varied with the grain type. Enzyme supplementation reduced ileal viscosity, particularly in birds that received the diet based on wheat. The birds on the barley-based diet had lower ileal digestibility of dry matter, protein and energy than those given maize and sorghumbased diets. The ileal digestibility of starch was increased by enzyme supplementation. Enzyme supplementation increased the number of total anaerobic bacteria in the gizzard of birds fed on sorghum and increased lactobacilli in the gizzard of those fed both sorghum and wheat. The birds fed the sorghum-based diet had the lowest counts of caecal total anaerobic bacteria and lactobacilli. Jejunal villus height and villus:crypt ratio of birds fed the barley-based diet were the lowest when compared with those fed the other diets. Enzyme application induced an increase in villus height and villus:crypt ratio of birds on wheat, crypt depth on barley and a reduction in crypt depth of chickens on the sorghum-based diets. The highest activity of maltase and the lowest activity of sucrase were observed in tissue from birds fed on maize and sorghum-based diets respectively. The differences in the performance of broilers on cereal grains could be explained by changes in intestinal morphology, enzyme activities and gut microflora as well as nutrient digestibility. The improved performance by supplemental enzyme in wheat-fed chickens was associated with beneficial changes in intestinal morphology and digesta viscosity.

The effects of phytate and phytase on broiler performance and cellular and humoral immunity was assessed by using 504 Cobb 500 female broilers fed nutritionally marginal diets. At 1 d of age, the chicks were randomly allocated to 6 treatments in a 2 x 3 factorial arrangement including 2 levels of phytate P (0.22 or 0.44%) and 3 dose rates of an Escherichia coli-derived phytase [0, 500, or 1,000 phytase units (FTU)/kg of feed]. Both low- and high-phytate diets were corn and soy based with the same nutritional specifications (AME 2,900 kcal/kg, CP 21.00%, Ca 0.78%, and nonphytate P0.28%), differing only in the concentration of phytate P. The immune status of birds was measured at 14, 21, and 28 d of age. The results revealed that phytase improved feed intake, BW, and feed conversion ratio (P < 0.05), whereas high dietary phytate depressed bird performance (P < 0.05). There was no interaction between phytate and phytase on bird performance. Feeding phytase increased the percentages of erythrocyte rosette-forming cells and erythrocyte-antibody complement cells by 3.03 and 1.83% at d 21, and by 2.76 and 2.20% at d 28, respectively (P < 0.05). The percentages of CD4(+)CD8(+) T lymphocyte subsets were also increased by phytase (P < 0.05), without affecting the ratio of CD4(+) and CD8(+). The levels of intestinal secretory IgA were improved with phytase at d 14, 21, and 28 (P < 0.05). Antibodies against Newcastle disease virus vaccine were enhanced at d 21 and 28 in the high-phytate diets with phytase addition (P < 0.05). Increasing the phytase dose to 1,000 FTU/kg did not improve immune function further than 500 FTU/kg. The results suggest that application of phytase in nutritionally marginal diets could enhance lymphocyte numbers and the seral and mucosal antibodies of 1- to 28-d-old broilers, suggesting that both phytate and phytase may have a role in gastrointestinal health and immune competence.

The possible interaction between dietary electrolyte balance (DEB=Na+K-Cl, mEq/kg of diet) and microbial phytase on the performance and nutrient utilization of broiler starters and litter quality was examined in this study. A 4 x 2 factorial arrangement of treatments was used with 4 levels of DEB (150, 225, 300, and 375 mEq/kg of diet) and 2 levels of phytase (0 and 500 phytase units/kg of diet). Experimental diets were based on corn, soybean meal, and canola meal and were formulated to contain a nonphytate P level of 3 g/kg. The DEB levels were altered by the use of sodium bicarbonate and ammonium chloride. Each diet was offered to 6 replicates of 8 birds each from d 1 to 21. Increasing the DEB values from 150 to 300 mEq/kg had no effect (P0.05) on the weight gains and feed per gain, but the gains were lowered (P0.05) and the feed per gain was increased (P0.05) at 375 mEq/kg. Feed intake was unaffected (P0.05) by DEB levels. Supplemental phytase improved (P0.05) the weight gains and feed intake at all DEB levels. Feed per gain was lowered (P0.05) by phytase addition, but a tendency for a DEB x phytate interaction (P=0.06) was also observed, indicating that the responses to phytase may be affected by DEB level. The responses in feed per gain were greater at the lowest DEB level, and phytase addition had no effect on feed per gain at the highest DEB level. Dietary electrolyte balance levels had no effect on the AME(n) and ileal N digestibility to 300 mEq/kg, but lowered (P0.05) both criteria at 375 mEq/kg. Phytase addition improved (P0.05) the AME(n) and ileal N digestibility. The improvements in AME(n) with 500 U/kg of phytase addition in 150, 225, and 275 mEq/kg DEB were 53, 60, and 38 kcal/kg of DM, respectively. The main effect of DEB was significant (P0.05) only for the ileal availability of Na and Cl, whereas added phytase influenced (P0.05) the ileal availability of Ca, P, Na, K, and Cl. The effects of DEB were significant (P0.05) for apparent ileal digestibility of all amino acids, except Ala (P=0.09), Arg, Met, and cystine. In general, the digestibilities of amino acids were unaffected when the DEB level was increased from 150 to 225 mEq/kg of diet, but decreased at the 300 and 375 mEq/kg levels. Phytase addition improved (P0.06 to 0.05) ileal digestibility of all amino acids, except Met and Tyr. Increasing DEB had adverse effects on excreta scores and DM content. Phytase addition, however, had no effect on excreta quality. The overall results of the present study suggest that variability in phytase responses in nutrient utilization may be explained, in part, by differences in dietary electrolyte levels.

A completely randomised design study with a 3 × 2 factorial arrangement was conducted. A total of 480 male broiler chickens were used to determine the influence of phytase addition, plant protein source [soybean meal, soybean meal + 200 g/kg of blue lupin meal (Lupinus angustifolius L.) or soybean meal + 200 g/kg yellow lupin meal (Lupinus luteus L.)] on performance of broiler chickens, ileal calcium (Ca), phosphorus (P) and protein digestibility, tibia bone characteristics and nitrogen-corrected apparent metabolisable energy. All diets were deficient in Ca, available P as well as lysine and total sulfur amino acids. Birds fed different protein sources were characterised by similar bodyweight gain and feed intake during the whole trial but feed conversion ratio was higher when birds were fed supplemented with yellow lupin meal (P < 0.05). Phytase improved bodyweight gain and feed conversion ratio regardless of protein source (P < 0.05). Diets supplemented with 200 g/kg blue or yellow lupin meal were found to be lower in nitrogen-corrected apparent metabolisable energy than soybean meal diets (P < 0.05). Birds fed diets supplemented with phytase were characterised by higher utilisation of Ca and P than birds whose feed was not supplemented with phytase (P < 0.05). Tibia bone ash as well as Ca content was similar across protein sources (P > 0.05), whereas tibia P content was lower when soybean meal or blue lupin meal was used (P < 0.05). Birds fed diets supplemented with blue lupin meal were characterised by the highest tibia P content (P < 0.05). Birds fed phytase-supplemented diets were characterised by higher tibia Ca and P content irrespective of protein source.

In order to examine the interactive effects of strontium and cholecalciferol in broiler nutrition a total of 288 male broiler chickens were fed over 28 days, eight different diets with six replicates comprising of two levels of vitamin D (5000 and 10 000 IU/kg) and four levels of strontium (0, 400, 800 and 1200 mg/kg) provided as strontium carbonate. Vitamin D and strontium produced a significant interaction on growth and feed efficiency with the addition of higher levels of vitamin D ameliorating the negative effects of strontium at 1200 mg/kg. The higher level of vitamin D also improved bodyweight gain (P < 0.05), had no effect on tibia bone composition but reduced calcium, phosphorus, potassium and magnesium retention (P < 0.05). Strontium supplementation produced no advantage to chicken performance but changed tibia bone composition. It was found that calcium and sodium maintained a ratio of ~30 : 1 in tibia bone. Vitamin D and strontium produced a significant physiological interaction and further research is required to elucidate optimum levels of supplementation for commercial broiler chicken production.

Background Biliary atresia (BA) is a rare, poorly understood liver disease of infancy that is fatal if not treated through early biliary drainage via the Kasai procedure. BA surgery was rationalised to three UK centres in 2002 following data supporting improved outcomes in institutions performing >5 Kasai per year. We have previously shown that outcomes in Scottish children were worse than expected in the years following initial rationalisation. Aims We aimed to expand the post-rationalisation cohort of BA cases in Scotland to examine epidemiology and outcomes. Methods Outcomes of the previously published 2002–2009 incident cohort was first expanded. New Scottish incident cases of BA born between 2010–2013, were obtained using data from specialist nurse/team knowledge. New data collection focussed on demographics, details of Kasai and outcomes (particularly 2 year transplant-free survival [2YTFS]). Accurate regional and national population data was obtained from the General Register Office for Scotland and statistics performed in R with Poisson regression analysis for incidence trends. Results 48 infants were initially identified, of whom 5 were excluded from outcome analysis (three with Kasai performed in Edinburgh, one with Conclusion BA atresia incidence appears relatively stable in Scotland but with an unexplained cluster of cases in Lanarkshire; examination of this cluster may provide epidemiological insight into disease pathogenesis Despite a significant reduction in time to Kasai, the 2YTFS in Scotland remains disappointing, is lower than the pre-rationalisation figure of 65% and is not currently an endorsement of centralisation of BA surgery in Scotland.

The effect of the supplementation of diets containing low available P concentrations with low and supra-activities of an Eschericia coli 6-phytase was assessed using growing broiler chicks. A total of 384 female Ross broiler chicks were weighed at d 1 of life and assigned to 1 of 8 experimental treatments. There were 12 replicate cages with 4 chicks per cage, and the diets were fed from d 1 of life for a period of 16 d. A positive control diet (5 g/kg of available P) and a negative control diet (3 g/kg of available P) were used, and 6 more diets were manufactured by supplementing the negative control diet with 150, 300, 600, 1,200, 2,400, and 24,000 U/kg of exogenous phytase. Body weight gain and feed conversion ratios were determined, as were nutrient digestibility coefficients and toe ash values. Birds fed the negative control diet had lower (P0.05) weight gains than those fed the positive control diet. The addition of exogenous phytase above 150 U/kg improved (P0.05) weight gain, toe ash percentage, and nutrient utilization of the birds fed the negative control diet. Furthermore, the 24,000 U/kg of diet improved (P0.05) toe ash percentage and the utilization of several nutrients beyond that of the lower doses of phytase. It can be concluded that the supplementation of diets containing 3 g/kg of available P with exogenous phytase can improve the performance of chicks to that of birds fed a diet containing 5 g/kg of available P. In addition, the use of high doses of phytase (1,000 U/kg of diet) can improve nutrient availability in poultry diets beyond that of diets containing lower (1,000 U/kg) phytase activities. These results may be mediated partially by reduced endogenous loss as well as an increase in the availability of dietary nutrients as indicated by improvements in digestibility coefficients.

1. In order to investigate the effects of xylanase, amylase, protease and phytase in the diets of broiler chickens containing graded concentrations of metabolisable energy (ME), two 42-d experiments were conducted using a total of 2208 broiler chicks (8 treatments with 12 replicate pens in each experiment). 2. Four diets including one positive and three negative control diets were used. Three maize/soybean meal-based negative control (NC) diets were formulated to be identical in available phosphorus (P), calcium (Ca) and amino acids but NC1 contained approximately 0.17 MJ/kg less ME than NC2 and approximately 0.34 MJ/kg less ME than NC3. A positive control (PC) was fed for comparison and was formulated to be adequate in all nutrients, providing approximately 0.63 MJ/kg ME, 0.13% available P, 0.12% Ca and 1 to 2% amino acids more than NC1. 3. The reduction in nutrient density between NC1 and PC was determined using ingredient quality models Avichecktrade mark Corn and Phychecktrade mark that can predict the response to exogenous enzymes in maize/soybean meal-based broiler diets. Supplementation of each diet with or without a cocktail of xylanase, amylase, protease and phytase gave a total of 8 dietary treatments in a 4 x 2 factorial arrangement. The same treatments and diet designs were used in both experiments but conducted in different locations using different batches of maize, soybean meal and minor ingredients. 4. In both experiments, digestibility was improved by the addition of exogenous enzymes, particularly those for P, Ca and certain amino acids. In addition, the supplementation of the PC with enzymes elicited a positive response indicating that over-the-top addition of xylanase, amylase, protease and phytase may offer a nutritionally and economically viable alternative to feed cost reduction. 5. It can be concluded that the digestibility of nutrients by broilers fed on maize/soybean meal-based diets can be improved by the use of a combination of xylanase, amylase, protease and phytase.

The effect of high (1000–3000 phytase units (FYT)/kg) doses of microbial phytase on performance, nutrient digestibility and plasma inositol concentrations in young Ross broiler chicks was investigated in two separate experiments. In both experiments pelleted corn/soy-based diets were used and experimental duration was from Days 8 to 21 and Days 15 to 28 in Experiments 1 and 2, respectively. Treatments in Experiment 1 were arranged as a 2 × 4 + 1 factorial with two concentrations of calcium and available phosphorus and four concentrations of phytase (0, 1000, 2000 or 3000 FYT/kg), with a reference diet containing additional phosphorus and calcium from inorganic sources. In Experiment 2 only four dietary treatments were used, being a nutritionally adequate positive control, a negative control formulated to be insufficient in calcium and available phosphorus and the negative control supplemented with either 1000 or 2000 FYT/kg exogenous phytase. In both experiments, phytase improved performance relative to the appropriate control diet and increased the retention of calcium and phosphorus (P < 0.001). Tibia strength and ash content were increased (P < 0.001) by phytase addition. Plasma inositol concentrations were substantially increased (P < 0.001) by phytase addition to the diet. As inositol has been found to be an insulin mimetic in a range of animal species, these results suggest that part of the beneficial effect of high doses of phytase in broiler production may be conferred via insulin-like mechanisms. The effect of phytase on the expression of insulin-sensitive glucose transport systems, gluconeogenesis and nitrogen cycling is an area for future research. It can be concluded that phytase is effective in improving performance of broiler chicks fed diets that are sufficient and insufficient in calcium and phosphorus. Furthermore, phytase addition results in increased plasma inositol concentrations that may be beneficial in nutrient transport and protein deposition.

Two 21-day studies were conducted with broilers to evaluate the efficacy of a bacterial 6-phytase from Citrobacter braakii and compare four Pi sources. The four sources were phosphates of monocalcium (MCP), dicalcium (DCP), tricalcium (TCP) with potassium phosphate (KH2PO4) acting as a ‘positive control’ reference. In each study, 336 4-day-old male birds (Ross 708) were blocked based on initial bodyweight (BW) and randomly allotted to one of seven diets with six replicate cages of eight birds each. Access to experimental diets and water from Days 4 to 25 post-hatching was ad libitum. In the first study, the seven diets were: (1) a low-P negative control (NC) corn-soybean meal basal diet formulated to contain crude protein (CP), Ca, total P, and non-phytate P (nPP) at 218, 9.0, 4.5, and 2.0 g/kg, respectively; (2) NC plus 0.75 g Pi from KH2PO4/kg; (3) NC plus 0.75 g Pi from MCP/kg; (4) NC plus 0.75 g Pi from DCP/kg; (5) NC plus 0.75 g Pi from TCP/kg; (6) NC plus phytase at 500 FYT/kg; (7) NC plus phytase at 1000 FYT/kg. Feeding the low-P NC diet reduced (P < 0.01) BW gain (BWG), feed intake (FI), and tibia ash. Supplementing the NC with Pi or phytase linearly improved (P < 0.01) BWG, FI, and tibia ash. Supplementing the NC with 0.75 g/kg Pi from MCP, DCP, or TCP were equipotent in improving BWG and FI; however, percent tibia ash was higher (P < 0.05) in birds fed MCP than either DCP or TCP. The second study was similar to the first study except that Ca, total P, and nPP in the NC were reduced to 7.0, 4.2, and 1.8 g/kg, respectively; and Pi from MCP, DCP, and TCP were reduced to 0.6 g/kg. Similar to observations in the first study, the low-P NC diet reduced (P < 0.01) BWG, FI, and tibia ash; and supplementing the NC with Pi or phytase linearly improved (P < 0.01) BWG, FI, P digestibility and tibia ash. Furthermore, supplementing the NC with 0.75 g Pi from MCP, DCP, or TCP per kg diet were equipotent in improving BWG, FI, and tibia ash though MCP resulted in superior (P < 0.05) retention of P compared with TCP. Results from both studies showed that the phytase was efficacious in releasing phytate-P for growth and bone mineralisation in chickens compensating, at least, the spared Pi, and that Pi sources commonly used in formulating diets of chickens may be different in their potential to supply digestible P.

We introduce transversality conditions for a piecewise smooth map in any dimension with a sufficiently regular discontinuity set. We prove that maps satisfying these conditions have certain nice properties and, among all maps with a common set of discontinuities, form an open and dense subset. This, in conjunction with other works of the author, implies the existence of stochastically stable invariant densities for an open and dense set of piecewise smooth expanding maps.

This study was conducted to determine the influence of maize endosperm type (soft or vitreous), drying temperature (60, 100, 140°C), and enzyme addition (no enzyme or phytase + xylanase) on broiler chicken growth, amino acid availability, and phytate phosphorus hydrolysis. One-day-old Ross-308 broiler chicks (total 1200) were allotted to floor pens with a randomised complete block design (2 × 3 × 2). Diets were formulated to be marginally deficient in Lys, total sulfur amino acids, calcium, and nonphytate phosphorus. A positive effect (P < 0.05) of enzyme addition on chicken bodyweight gain to day 35 was observed (1884 vs 1940 g). Bodyweight gains and feed conversion ratios (FCR) were linearly depressed when drying temperature was increased. Chickens fed vitreous maize were characterised by lower bodyweight gain (1932 vs 1893 g; P < 0.05) and higher FCR (1.796 vs 1.840g : g; P < 0.05). There were no interactions between any of the main effects for overall performance metrics. The use of phytase improved phytic acid digestibility (0.302 vs 0.389; P < 0.05) but phytic acid digestibility was unaffected (P > 0.05) by drying temperature or hardness. The highest drying temperature had a negative effect on amino acids digestibility (P < 0.05). The use of phytase and xylanase improved amino acid apparent ileal digestibility (P < 0.05), except for Cys, Met, and Phe. Results from this study show that drying temperature and vitreousness of maize influence the nutritional value of this grain for broilers. Part of the beneficial effect of the addition of phytase + xylanase to diets with overheated maize for poultry appears to be mediated through an improvement in amino acid availability.

A total of 144 Cobb 500 broilers were used to investigate if modern commercial broilers could regulate their calcium (Ca) intake using choice feeding and whether separating the delivery of a portion of the Ca from the mixed ration would be advantageous for performance and nutrient recovery. Birds were fed corn+soy-based diets formulated to contain 2.5, 5.0, 7.5 or 10.0 g/kg total Ca and all groups had access to a separate Ca source (CaCO3). The trial was conducted from Day 1 to Day 21 and birds had ad libitum access to both the experimental diets and a separate Ca source throughout. Total feed and separate Ca intake were monitored daily, weight gain and feed intake weekly and on Day 21, the apparent ileal digestibility of DM, nitrogen, selected minerals and amino acids were determined. Consumption of the separate Ca source increased (P < 0.05) with decreasing total Ca concentration of the mixed ration. No differences (P > 0.05) in toe ash were found. Increasing dietary Ca concentration negatively influenced the apparent ileal digestibility of DM, nitrogen, minerals and amino acids. It can be concluded that broilers can select and consume Ca from a separate source to broadly maintain their requirement. Feeding a separate source of Ca in combination with reduced dietary Ca in the mixed ration had beneficial effects on nutrient digestibility, phosphorus excretion and performance.

Sorghum-based diets were offered to male Ross 308 chicks from 7 to 28 days post-hatch as a 2 × 3 factorial array of treatments. The diets were based on either a white (Liberty) or red (Venture) sorghum that were finely ground through a 2.0-mm hammer-mill screen before incorporation into diets that were steam-pelleted at conditioning temperatures of 70°C, 80°C and 90°C. Protein solubilities and concentrations of disulfide bonds and free sulfydryl groups in sorghums and sorghum-based diets were determined. Concentrations of phenolic compounds and antioxidant activities in both sorghums were analysed and the presence or absence of a pigmented testa was detected. In vivo parameters assessed included growth performance, relative gizzard weights, nutrient utilisation and apparent starch and nitrogen (N) digestibility coefficients were determined at four small-intestinal sites. Increasing conditioning temperatures depressed dietary protein solubilities and induced changes in concentrations of disulfide bonds and free sulfydryl groups that were more pronounced in red sorghum-based diets. The red sorghum contained a higher concentration of phenolic compounds and had a higher antioxidant activity than did white sorghum. A pigmented testa was not present in both sorghums, which indicates that they do not contain condensed tannin. There was a significant interaction between sorghum type and conditioning temperature for weight gain; however, diets based on white or red sorghums did not generate any significant differences in weight gains, feed intakes or feed conversion ratios as main effects. It was anticipated that birds would perform better on white sorghum-based diets but the likelihood is that the fine 2.0-mm grind disadvantaged the softer-textured white sorghum. As main effects, red sorghum-based diets had significantly higher densities of N-corrected apparent metabolisable energy, a higher starch digestibility coefficient in the distal jejunum and higher N digestibility coefficients in the distal jejunum, proximal ileum and distal ileum than did white sorghum-based diets. Red sorghum-based diets generated significantly heavier relative gizzard weights, which appeared to enhance N digestibility coefficients relative to the white sorghum diets. Increasing conditioning temperatures linearly increased starch digestibility coefficients in the proximal jejunum and distal ileum and N digestibility coefficients in the proximal jejunum, distal jejunum and distal ileum to significant extents. Conditioning temperatures did not significantly influence gizzard weights or parameters of growth performance and nutrient utilisation. Several significant interactions between the main effects were observed, which suggests that the two sorghums responded somewhat differently to increasing conditioning temperatures.

The effects of organic selenium (Se) supplementation of diets for broiler chickens were evaluated in the present study. Broiler diets had average background Se concentrations of 0.36 mg/kg Se (control diet) and were supplemented with two organic Se sources, namely BiOnyc® Tor-Sel (selenohomolanthionine = SH) and Alltech’s Sel PlexTM (selenomethionine = SM); their addition increased dietary selenium concentrations by an average of 0.57 mg/kg Se. Their effects on growth performance, nutrient utilisation and oxidative status of broiler chickens were determined. Growth performance was very similar across all dietary treatments; in contrast, significant differences in nutrient utilisation were observed. The N-corrected apparent metabolisable energy value for the control group (14.14 MJ/kg) and SH (14.15 MJ/kg) diet was significantly (P < 0.01) higher than that for the SM (13.64 MJ/kg) diet. Alternatively, N retention with the SM (68.4%) diet was significantly (P < 0.005) higher than that for the control (65.2%) and SH (64.5%) diets. Neither of the Se sources influenced plasma concentrations of reactive oxygen metabolites, biological antioxidant potential and advanced oxidation protein products. The activity of glutathione peroxidase, superoxide dismutase in both plasma and tissues samples and the concentration of plasma glutathione were increased by SH and SM compared with the control group. Our findings suggest that SH and SM improved the antioxidant status of broilers by elevating activities of antioxidant enzymes and concentrations of antioxidant. Both Se supplements significantly (P < 0.001) increased Se concentrations in liver and muscle, and in liver tissue there was no statistical difference between the two supplements. However, SH generated significantly higher Se concentrations in muscle tissue (0.283 versus 0.257; P < 0.005) than did SM. In summary, SH was at least the equivalent to SM as a source of organic Se for broiler chickens under the conditions of the present feeding study. This is reflected in the outcome that SH generated significantly higher Se concentrations in muscle tissue than did the alternative Se supplement.

The therapeutic use of vitamin D3 and strontium has been successful for the treatment of osteoporosis in humans; however, the value of similar strategies in poultry is not clear. Male Ross broiler chicks (n = 216) were used in a 28-day broiler trial to assess effects of vitamin D3 and strontium supplementation on performance, nutrient retention, bone composition, and bone mass. Treatments included an industry-standard control diet and five additional diets where vitamin D3 was added at 5000, 20 000, or 35 000 IU/kg and strontium was added at 0 or 1200 mg/kg in a 3 × 2 factorial design. Broiler chickens supplemented with strontium and additional vitamin D3 did not increase bodyweight; however, there was a significant improvement in feed efficiency at medium levels of vitamin D3, and although not statistically significant, there was also an improvement in feed conversion ratio with strontium supplementation at normal vitamin D3 concentrations. Strontium supplementation at normal levels of vitamin D3 significantly (P < 0.01) increased calcium, phosphorus, sodium, potassium, and magnesium retention. A high concentration of vitamin D3 produced a significant improvement in apparent metabolisable energy, protein, and dry matter utilisation in the broiler chicken. Paradoxically, however, there was a detrimental effect of high vitamin D3 on bodyweight and feed efficiency, which was partially ameliorated by strontium supplementation. Strontium addition did not change bone mass but did change bone composition. High levels of vitamin D3 significantly (P < 0.01) reduced bone ash content and increased strontium content of bone. In conclusion, both vitamin D3 and strontium have the potential to positively influence the performance, mineral retention, and bone characteristics of broiler chicks. However, as with calcium and phosphorus, vitamin D3 and strontium interact and so more research is required with strontium on the optimum dose rate and its relationship with vitamin D3, calcium, phosphorus, and IGF-1 in broiler nutrition.

The use of phytochemicals in poultry diets has increased, especially with the withdrawal of antibacterial growth promoters. The choice and use of phytochemicals in poultry diets has been based on t...

A study was conducted to examine the effect of starch and nitrogen digestion kinetics on broiler performance using sorghum-based diets as a model. Three sorghum varieties with red, white and yellow pericarps and three feed forms, mash, intact pellets and reground pellets, constituted a 3 × 3 factorial array of dietary treatments. Starch and nitrogen digestion kinetics were determined using an exponential mathematical model to relate digestion coefficients in the proximal jejunum, proximal ileum and distal ileum with mean retention times in each segment. There were interactions between sorghum variety and feed form for starch and nitrogen digestion kinetics. Steam-pelleting at a conditioning temperature of 90°C (unprocessed mash versus reground pellets) substantially influenced starch digestion rate in red and yellow sorghum-based diets, but not in white sorghum-based diets. Alternatively, with nitrogen digestion rate, there were no significant differences in yellow sorghum-based diets between feed forms but there were in red and white sorghum-based diets. The digestion rate of starch was more rapid than nitrogen, especially in the proximal jejunum. Starch digestion rates were significantly correlated with nitrogen retention but this was not the case with nitrogen digestion rates. The rate of glucose absorption from predicted glycaemic indices was highly correlated with enhanced feed efficiency. Thus this study demonstrates that even under ad libitum feeding regimes, kinetics of starch and protein digestion regulated feed efficiency and nitrogen retention in broiler chickens. The dynamics of starch and protein digestion were more accurate indicators of feed efficiency and nitrogen retention than apparent ileal starch and nitrogen digestibility.

A red sorghum was mediumly ground (3.2 mm) and incorporated into broiler diets that were steam-pelleted at conditioning temperatures of 65, 80 and 95°C and offered to male Ross 308 chicks from 7 to 28 days post hatch. This diet was also fed as unprocessed mash, reground mash following steam-pelleting at 95°C and diets steam-pelleted at 80°C were fed without and with exogenous protease. A nutritionally equivalent diet based on a mediumly ground white sorghum steam-pelleted at 95°C completed the seven dietary treatments each of which were offered to seven replicates of six birds per cage. The effects of treatment on growth performance, relative gizzard weights, nutrient utilisation [apparent metabolisable energy (AME), nitrogen (N) retention, and N-corrected AME] and apparent digestibility coefficients of starch and N in four segments of the small intestine (proximal and distal jejunum, proximal and distal ileum) were determined. Elevating conditioning temperatures at which the red sorghum-based diets were steam-pelleted reduced their protein solubilities and linearly reduced concentrations of free sulfydryl groups (P < 0.02) and the two parameters were positively correlated (P < 0.01). Elevating temperatures also linearly increased relative gizzard weights (P < 0.02). However, increasing conditioning temperatures linearly depressed feed conversion efficiency (P < 0.02), tended to depress weight gain (P < 0.08) but did not influence nutrient utilisation parameters (P > 0.50). Increasing conditioning temperatures influenced N digestibility coefficients in the distal jejunum (P < 0.01) and distal ileum (P < 0.05) in a quadratic manner. N coefficients varied from 0.565 to 0.538 and 0.638 in the distal jejunum with increasing conditioning temperatures; however, starch digestibility coefficients were not significantly influenced by conditioning temperatures. Birds offered the white sorghum-based pelleted diet conditioned at 95°C significantly outperformed (P < 0.05) their red sorghum counterparts in terms of weight gain, feed per gain, AME, N retention, starch and N digestibility coefficients in the distal ileum. The differences in starch digestibility between the two sorghum varieties along the small intestine were pronounced and the possible contributing factors are considered. Diets fed as intact pellets generated greater feed intakes and weight gains than the average of the two mash diets. In red sorghum-based diets, distal ileal starch digestibility coefficients of intact pellets were inferior to the unprocessed and reground mash. However, the distal ileal N digestibility coefficient of the unprocessed mash diet was 3.5% higher than the reground mash diet and 8.3% higher than the intact pelleted diet. The inclusion of a Bacillus lichenformis-derived protease in red sorghum-based steam-pelleted at 80°C significantly (P < 0.05) increased N digestibility coefficients in the distal jejunum, proximal ileum and distal ileum. Also, this protease significantly increased starch digestibility coefficients in the distal jejunum and proximal ileum. The implications of these findings in respect of feeding broiler chickens sorghum-based diets are discussed.

A study was designed to assess the impact of water-soluble proteins and peptides extracted from meat and bone meal (MBM) on broiler chick performance, following their oral delivery during the early post-hatch period. Proteinaceous material was fractionated by size exclusion filtration into weight ranges of 100 kDa (Fraction 3; 0.8 mg protein/mL), which formed the three protein fraction treatments. A total of 1 mL of each of the respective preparations was delivered orally via gavage over 4 days (0.25 µL each day) to Cobb broiler hatchlings. Three control groups: control–unhandled, control–phosphate-buffered saline and control–handled were also included. Chicks were grown to 30 days of age. Feed intake, chick weight gain and feed conversion ratio were determined from day old through to 29 days of age. On Days 10, 16, 23 and 30, the weight of the breast and the small intestine was determined from 10 birds/treatment. For all parameters measured there was no interaction between experimental week and protein fraction treatment. Chicks receiving Fraction 2 had a statistically significant increase in feed intake and weight gain (P = 0.012) compared with the control–unhandled chicks. Chicks receiving Fraction 2 also demonstrated a numerically higher final bodyweight. Mass spectrometric analysis of all three fractions revealed that they each contained a wide array of proteinacious material. The results of this study suggests the likelihood that protein or protein-derived fragment components within the 3–100 kDa molecular weight range of MBM can generate improvements in broiler chick production, and thus promote the need for further research to identify the specific protein(s) responsible for the observed positive growth effects.

The recent increase in free-range meat and egg production and consumption has led to extensive investigation in this area and has revealed that the level of animal performance achieved in such systems is low compared with that achieved in conventional production systems. In Australia, this difference has been attributed either to the absence of in-feed antibiotics or to range access, which may result in exposure to detrimental climatic conditions, predators, disease, welfare challenges and nutrient dilution. Moreover, although poultry in free-range systems have ready access to outside runs, not all birds utilise them optimally. Pasture consumption results in dilution of energy and protein intake and may cause impaction and dietary electrolyte imbalance. This paper provides an overview of these issues to provide a conceptual framework for further study in this area.

(2003). Phytic acid and the implications for protein utilisation by poultry. British Poultry Science: Vol. 44, No. sup1, pp. 36-37.

Sorghum grains with red, white and yellow seed colours were coarsely ground and incorporated into nutritionally equivalent diets that were offered to broiler chicks in three feed forms. The diets were fed as mash or steam-pelleted at a conditioning temperature of 90°C and fed as intact pellets or ground back into mash as reground pellets. The effects of a 3 × 3 factorial array of dietary treatments offered to male chicks from 6 to 27 days post-hatch on growth performance, nutrient utilisation and apparent digestibility coefficients of starch and nitrogen (N) at the proximal jejunum, proximal ileum and distal ileum were determined. Feed form had a greater impact on the parameters assessed than did sorghum seed colour, but several interactions between these main effects were observed. Steam-pelleting diets reduced protein solubility and this was correlated with increased concentrations of disulfide bonds and decreased concentrations of free sulphydryl groups. Steam-pelleting diets significantly depressed N retention in broiler chicks and this reduction was appropriately correlated with concentrations of disulfide bonds and free sulphydryl groups and dietary protein solubility. While N retention was depressed, in a curious outcome, steam-pelleting diets did not compromise N digestibility along the small intestine. Steam-pelleting diets significantly increased starch digestibility coefficients in the proximal jejunum, with differing responses among the sorghums, but not in the two ileal levels. Phytate concentrations in the three sorghums were negatively correlated with N digestibility coefficients at the proximal jejunum and proximal ileum. The implications of the present feeding study in relation to the performance of broiler chickens offered steam-pelleted, sorghum-based diets are discussed.

The use of alternative protein sources in ruminant diets is of interest because of restrictions on the use of animal proteins, loss of nitrogen (N) compounds to the environment and efforts to reduce costs of systems. A problem of some protein-rich-ingredients is that they degrade rapidly in the rumen. The use of tannins has been proposed as a means of reducing the extensive dietary protein degradation in the rumen. However, condensed tannins have been reported to exert detrimental effects on gut microflora and on the gastrointestinal tract, and they can affect post-rumen digestion. The two experiments reported here aimed to study the influence of quebracho tannins (QTs) on ruminal degradation of peas (Pisum sativum) and sweet lupins (Lupinus luteus), and to investigate the effect of QTs on postrumen digestibility of these feeds using a poultry model.