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Effective functionality of the gastrointestinal tract (GIT) and its health, are important factors in determining animal performance. Several, complex mechanisms are involved in the regulation of GIT functionality and health, therefore it is crucial to deepen our knowledge of these interactions so that strategies for the modulation of GIT functionality and health, in context of improved animal performance, can be developed. The concept of “gut health” has started to attract significant interest within the animal science community, however a clear definition of gastrointestinal health and functionality and how it can be measured is lacking. Therefore, this review will present a new definition of gastrointestinal functionality and will address how optimal gastrointestinal functionality can promote animal performances and welfare. The key components of gastrointestinal functionality reviewed in this article are: diet, effective structure and function of the gastrointestinal barrier, host interaction with the gastrointestinal microbiota, effective digestion and absorption of feed and effective immune status. While the relationships between these areas is extremely complex, a multidisciplinary approach is needed to develop nutritional strategies that would allow farm animals to become more resilient to the environmental and physiological challenges that they will have to endure during their productive career. As the demand of animal products from the rapidly growing world human population is ever-growing, the aim of this review is to present animal and veterinary scientists and nutritionists, a new definition of gastrointestinal functionality that can be used to establish a multidisciplinary approach to increase animal health, welfare and performance.

Objective: Pellet durability, particle size distribution, growth response, tibia bone characteristics and energy retention were measured to evaluate cassava as an alternative energy source to replace maize in broiler diets with or without Ronozyme (A+VP) enzyme composites.Methods: A total of 480 one-day broiler chicks were randomly assigned to 8 treatments in a 4×2 factorial arrangement. Four levels of cassava: (0%, 25%, 50%, 75%) and 2 levels of enzymes (0 and 500 g/tonne) were used. Each treatment was replicated six times, with ten birds per replicate.Results: The particle size distribution in the diets showed an increasing trend of small particles with increase in cassava level. Pellet durability decreased (p

The statement ‘phytic acid is ubiquitously present in non-ruminant animal diets’ is often made in scientific manuscripts oriented toward phytase, mineral and amino acid nutrition, monogastric animal performance and skeletal development. However, it is increasingly the case that this statement is at best misleading and at worst entirely incorrect. Phytase bioefficacy is at an unprecedented high in the life cycle of this technology and product cost is at an all-time low, two factors which have contributed to a climb in inclusion concentration and an axiomatic decrease in dietary phytic acid concentration. Though complete dephytinisation of monogastric animal diets may be unrealistic due to the presence of variable concentrations of recalcitrant phytic acid in localized regions of cereals, oilseed meals and grain legumes, the vast majority of reactive phytic acid is rapidly degraded to innocuous lower esters in the proximal GI tract. Thus, the nutritional paradigm has shifted from formulating diets to accommodate the presence of phytase to formulating diets to accommodate the absence of phytic acid. These are not trivial distinctions but may have considerable implications for animal performance and the optimal balance of nutrients in the diet. It is the purpose of the present article to consider the breadth of effect of the ingestion of phytic acid and the likely consequence of an ostensibly dephytinized diet on nutrition and animal performance. The concept of ‘phytate-free nutrition’ is posited and nutritional strategies to maximise the likelihood of observing measurable benefits from the lack of this nutritional obstacle are discussed around three conceptual pillars: phosphorus, extra-phosphoric effects and myo-inositol.

The effect of phytase on phosphorus retention, broiler (Gallus gallus) performance and bone mineralization in diets with reduced inorganic phosphate concentration is well documented. Furthermore, so-called 'extra-phosphoric' effects of phytase have been described in the literature that may be associated with changes in mineral and amino acid partitioning and requirements per se. In particular, the role of myo-inositol in phytase responses is implied but not well elucidated. It was the purpose of the experiment reported herein to explore the effect of phytase on broiler growth, nutrient digestibility, blood biochemistry and gene expression. A 5-week broiler floor pen trial was conducted to evaluate the effect of supplementation of a moderately phosphorus-deficient diet with 1000 U/kg of a 6-microbial phytase. Parameters measured were growth performance, phosphorus (P), calcium (Ca) and myo-inositol plasma concentrations, apparent ileal P digestibility, bone mineralization, breast meat weight and Pectoralis major muscle transcriptome. Supplementation of the diet with phytase improved weight gain during the starter period (18%) and the whole period (24%) compared with animals that received the control diet (p

A 14-d experiment was conducted to study the effects of 2 dietary variables on efficacy of a 6-phytase from Citrobacter braakii on broiler growth performance and tibia mineralization. Diets were formulated with or without nutrient matrix values for phytase as negative or positive control (NC or PC, respectively) and with 2 Ca:total P (tP; 2:1 or 2.5:1). The diets were supplemented with 0, 1,000, or 2,000 phytase units (FYT)/kg, thus producing a 2 × 2 × 3 factorial arrangement. Birds and feed were weighed on d 7 and 21, and tibia bones were collected from all the birds on d 21. The main effects of nutrient matrix, Ca:tP, and phytase supplementation were significant (P0.05) for all the growth performance responses (except for G:F for which there was no effect of matrix). The Ca:tP × phytase and matrix × phytase interactions were significant (P0.05) for weight gain. In the PC diets, phytase increased weight gain (P0.05) relative to the control only in diets with 2,000 FYT/kg, whereas in NC diets weight gain increased (P0.01) only from 0 to 1,000 FYT/kg levels. Broilers consuming diets with 2.5:1 Ca:tP had lower (P0.05) tibia ash, whereas phytase increased (P0.01) tibia ash, Ca, P, and Zn but decreased (P0.01) tibia K. Phytase supplementation of diets with 2:1 Ca:tP increased (P0.05) tibia P in birds receiving 1,000 FYT/kg relative to the control with no further increase at 2,000 FYT/kg, whereas each level of phytase supplementation increased (P0.05) tibia P in the diets with 2.5:1 Ca:tP. It was concluded that the best response to lower phytase supplementation (1,000 FYT/kg) was in NC diets with narrow Ca:tP, whereas the best response to higher level of phytase supplementation (2,000 FYT/kg) was achieved in diets in PC diets with wide Ca:tP.

Two studies were conducted to determine the true P digestibility (TPD) of black-eyed pea (BEP) and peanut flour (PNF) and the TPD response to phytase supplementation using the regression method. Sequential diets containing 115, 230, or 345 g of BEP/kg (experiment 1) and 115, 230, or 345 g of PNF/kg (experiment 2) without or with 1,000 units of phytase/kg were formulated. Chromic oxide was added to the diets at the rate of 5 g/kg as an indigestible marker. At 20 d posthatch in each study, 384 male broiler chickens (Ross 708) were weighed and allotted to the diets with 8 replicates of 8 birds each in a randomized complete block design. The birds had free access to the experimental diets until d 26 posthatch. In both studies, dietary P increase and phytase supplementation improved (P < 0.001) growth performance of the broiler chickens. There were linear increases (P < 0. 001) in ileal and excreta P output but a linear decrease (P < 0.001) in apparent P digestibility with an increase in dietary P levels. Phytase supplementation reduced (P < 0.001) ileal P and excreta P output and increased (P < 0.001) apparent P digestibility and retention. Apparent Ca digestibility was affected (P < 0.01) by P level and phytase addition in BEP and by P level (P < 0.05) in PNF. Apparent Ca retention in BEP increased (P < 0.05) with phytase addition. The TPD in the BEP increased (P < 0.01) from 29 without phytase to 83% with the addition of 1,000 units of phytase/kg. There was an increase (P < 0.01) in TPD of PNF from 67 without phytase to 75% with phytase supplementation. There was a corresponding increase (P < 0.01) in true P retention from 10% without phytase to 61% with phytase in birds on BEP diets and an equivalent increase (P < 0.01) in true P retention from 74% without phytase to 84% with phytase in birds that received the PNF diets.

2 Abstract: Enzymes are widely used in feed to improve utilization of nutrients and it is generally acknowledged that phytases, by improving phytate phosphorus utilization are an important tool to reduce phosphorus pollution and the environmental problems derived from this such as eutrophicatio n. Lately, the use of proteases as feed enzymes has gained interest. Proteases are added to feed with the purpose of increasing dietary protein hydrolysis and thus enabling improved nitrogen utilization. When animals utilize nitrogen better, there is a possibility to decrease the diet protein content and in turn also reduce the content of nitrogen in manure. The environmental consequences of decreased dietary protein content and reduced nitrogen excretion were investigated in a Life Cycle Assessment (LCA), which considered all steps in broile r production from production of feed ingredients, to the broilers leaving the chicken house, including the use of manure. Wide ranges of environmental impacts were analyzed, covering emissions of nitrous compounds to both air and the aquatic environment. Significant benefits were obtained for all impacts considered. Most important were the benefits related to reduced emissions of ammonia, which help reduce both health risks and environmental impacts, such as acidification and eutrophication. The largest effects were obtained when protease was used as a tool to allow for lower diet protein content. However, even when used in a diet with normal protein level significant benefits were observed. It is illustrated that the use of protease can contribute significantly to current efforts to reduce nitrogen emissions from livestock production.

Effects of a novel serine protease, RONOZYME® ProAct (RPA) on protein solubilisation, hydrolysis and digestibility were tested in a gut simulation model. Furthermore, the effects of RPA (supplemented at 15,000 PROT/kg feed) on growth performance and nutrient digestibility were tested in two in vivo broiler experiments each arranged in a 2×2 factorial design (enzyme x sex in experiment 1 and enzyme x protein level in experiment 2). Each dietary treatment had 12 replicates. In experiment 1, birds were fed 12.7 MJ ME per kg iso-energetic diets in 2 phases. Each diet was fed without or with RPA (C or C+RPA, respectively) to either males or females. In experiment 2, two diets were fed in four treatments. Diet 1 (211 and 200 g CP per kg feed in the starter and grower phases respectively) was fed without or with RPA (NP or NP+RPA, respectively). Diet 2 (200 and 190 g CP per kg feed in the starter and grower phases respectively), was fed without or with RPA (LP or LP+RPA, respectively). At the end of each experiment, eight male birds per treatment were randomly selected and used for ileal digestibility measurements. In vitro, RPA significantly increased the degree of protein hydrolysis, solu-bilisation and digestibility. In males, C+RPA was significantly better than C in WG (2,393 g vs. 2,262 g) and FCR (1.60 vs. 1.65). In females, C+RPA was better than C in FCR (1.37 vs. 1.39) in the starter phase. The FCR of LP+RPA was significantly better than LP. In experiment 1, RPA significantly increased ileal protein (82.8% vs. 76.9%) and energy (77.8% vs. 70.6%) digestibilities. In LP, RPA significantly improved energy digestibility (76.6% vs. 75.5%). These results suggest that RPA can improve broiler performance by enhancing protein and energy digestibility.

Two separate randomised block design experiments were each carried out for 13 months to investigate the effects of replacing, in-part, soybean meal (SBM) and wheat by graded levels of faba beans (FB) and field pea (FP) in a basal diet of wheat-SBM, balanced for amino acids, similar in crude protein (CP) and metabolisable energy (ME) on Lohmann hens. Traits studied included ; egg production, feed consumption, body weight gain, feed, energy and protein utilisations, and egg quality. Increasing dietary FB up 400g/kg (no SBM) decreased hen-day egg production, from 85 to 75%. Average egg mass significantly reduced from 50.8-43.5g/(hen*d). Feed consumption was similar (110 to 113g/(hen*d)). Increasing FB increased ME and CP required for egg production. FB had no significant effect on the shell strength, shell fraction and yolk index of eggs ; meanwhile it decreased the yolk fraction, and increased yolk colour, albumen fraction and albumen index. Most traits studied, were statistically similar up to 160g FB/kg feed. Increasing levels of FP up to 500g/kg did not significantly affect hen-day egg production and egg mass per day, although feed consumption increased. Body weight gain linearly dropped with increasing FP. FP had no significant effect on any of the egg quality traits studied. 16% FB and 50% FP could be included in layers diet without any significant effects on egg production or quality.

A 14-d broiler experiment was conducted to assess the effects of 2 dietary variables on efficacy of a bacterial 6-phytase from Citobacter braakii on nutrient and phytate P (PP) utilization. Diets were formulated with or without nutrient matrix values (matrix) for phytase as negative control (NC) or positive control (PC), respectively, and with 2 Ca:total P (tP) levels (2:1 or 2.5:1). The diets were supplemented with 0, 1,000, or 2,000 phytase units (FYT)/kg of diet, thus producing a 2 × 2 × 3 factorial arrangement. Excreta were collected on d 19 to 21 and ileal digesta on d 21. There was no 3-way interaction on digestibility of any nutrient. There was matrix × phytase (P0.01) interaction for Ca and DM digestibility and Ca:tP × phytase interaction (P0.05) for acid hydrolyzed fat and Ca and P digestibility. Prececal flow of Mn, Zn, and Na was greater (P0.05) in NC diets, whereas phytase increased (P0.05) prececal flow of Mg, Fe, Mn, and Zn but decreased (P0.05) prececal Na flow. Total tract PP disappearance and total tract Ca retention increased (P0.05) with phytase supplementation in diets with 2:1 Ca:tP, whereas there was no effect of phytase supplementation on PP disappearance or Ca retention in diets with 2.5:1 Ca:tP. Total P and Ca retention were reduced (P0.05) in PC and NC diets when Ca:tP increased to 2.5:1, but the depression was more pronounced in the NC diet. In addition, PP disappearance decreased (P0.05) with increasing Ca:tP in the PC diets, but there was no effect of widening Ca:tP on PP disappearance in NC diets. It was concluded from the current study that the effect of phytase supplementation on P utilization is reduced when diets contain adequate P as exemplified in the PC diets and that the negative impact of wide Ca:tP is more pronounced in diets with phytase matrix allowance as exemplified in the NC diets.

Bambara groundnut (Vigna subterannea)--a leguminous root nut, which grows in the tropics and subtropics--was used in an experiment to test its effect on the performance of growing broiler chicks. Performance was measured by monitoring growth, measuring nutrients and energy balances and also by determining nutrient accretion. Twelve-day old broiler chicks, kept in individual metabolic cages, were used in an experiment in which birds were equally allotted (n = 10) into a control (fed high performance diet made up principally of wheat and soybean meal) and 6 test groups fed diets containing 19, 76 and 95% raw or autoclaved bambara groundnuts. All diets were similar in energy, nitrogen and total lipid contents. Diets were also balanced for amino acids, vitamins and minerals in accordance to the specific requirements of the birds. Feed and water were provided ad libitum. Growth performance was monitored over 15 days. Nutrient and energy balances were measured by use of TiO2 as marker. The comparative slaughter technique was implored for the determination of energy and nutrient accretion. The results showed that the level of raw or autoclaved bambara had no significant influence on feed intake. Increasing the bambara level in the diets caused a general linear drop in the performance of the broilers. However, with up to 95% bambara in the diet, the general performance was still above 75% compared to the control. Increasing levels of bambara groundnut caused a decrease in the metabolizability of energy and efficiency of utilisation of ME for BWG. The animals retained more water with increasing levels of raw bambara in the diets while autoclaving increased their DM content to levels comparable to the control. The protein composition of gain was comparable at all levels of inclusion. In general autoclaving improved the performance of bambara.

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.