Effects of phytase supplementation on production performance, egg and bone quality, plasma biochemistry and mineral excretion of layers fed varying levels of phosphorus.

Excessive fecal excretion of phosphorus (P) has increasingly become an environmental issue due to oversupply of P in layer rations, and thus it is imperative to minimize safety margins for P to ensure the sustainability of the egg industry. In this study, a 12-week feeding trial (22 to 34 weeks of age) was conducted to evaluate the effects of phytase supplementation on production performance, plasma biochemistry, egg and bone quality and P excretion of laying hens fed various levels of non-phytate P (NPP). Forty-eight Lohmann white laying hens were randomly allocated to one of six corn-soybean meal-oat-based diets: diets containing 2.0, 2.5 or 3.0 g/kg NPP without phytase, and diets containing 1.0, 1.5 or 2.0 g/kg NPP with phytase (1 000 U/kg diet) where phytase inclusion was expected to provide 1.0 g/kg NPP to laying hens, thus making the phytase-unsupplemented treatment served as a control for the phytase-supplemented treatment accordingly. Productive performance was recorded during the experimental period. Blood and egg samples were collected, and digestibility studies were conducted at weeks 6 and 12 of the experiment. Bone mineralization was evaluated at the end of the experiment. Egg weight and egg production, feed consumption, BW and feed conversion ratio of laying hens fed lower NPP diets supplemented with phytase were comparable to those of hens fed high NPP phytase-unsupplemented controls. Eggshell thickness, specific gravity, Haugh units, tibia bone mineral density, tibia ash percent, plasma P and other biochemical parameters were not significantly different among dietary treatments. Total P intake, excretion and retention were affected by diet (P < 0.001), but its deposition in eggs was not significantly different. Contrast analysis further showed that total P excretion of phytase present vs phytase absent was averagely reduced by 40.4 mg/hen per day (P < 0.01). Moreover, total P excretion was linearly (P < 0.01) reduced with lowering dietary NPP, and this relationship was similar regardless of whether phytase was supplemented or not. The results from this study indicated that NPP levels in laying hen diets could be reduced to 1.0 g/kg (excluding the portion of NPP released by phytase) with the inclusion of phytase, without negative effects on production performance and health of the hens, thereby diminishing P excretion into environment.

Assessment of the minimal available phosphorus needs of pullets during the pre-laying period.

Dietary phosphorus (P) oversupply is costly to the poultry industry and represents a point source of excessive P discharge to the environment via manure application to soils. The current study was conducted to investigate the effects of dietary available P (AP) level on growth performance, plasma biochemistry, bone characteristics, and P flow in order to assess minimal AP needs of pullets during the pre-lay period. A total of 192 Lohmann pullet chicks were randomly allocated to one of 4 treatments with 8 replicate cages of 6 birds per cage. The pullets of Low (L; the lowest AP regimen) were fed diets in a sequence of 0.200, 0.175, and 0.150% AP for the age period of 0 to 4 wk, 4 to 8 wk, and 8 to 16 wk, respectively. The AP level was increased by an increment of 0.1% in each phase in Low-Medium (LM), Medium-High (MH) and High (H), thus making H (control) consisting of 0.500, 0.475, and 0.450% AP. Overall, there were no main effects of treatment on body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). However, compared with the H treatment, BWG or FI of the L treatment was lower during the first 8 wk post-hatch, but became comparable or higher over the last 8 wk (P < 0.05); FCR of L birds was greater over wk 0 to 4 but became smaller over wk 8 to 16 (P < 0.05). Plasma P was lower in L than H treatments at wk 8 but turned comparable at wk 16 (P < 0.001). Bone characteristics were not different for pullets fed various AP regimens. Total P intake and excretion were reduced with lowering dietary AP (P < 0.001), but its retention percent was not affected. The results indicated that the lowest AP regimen (0.200-0.175-0.150%) in the current study was adequate to support healthy growth and development of pre-lay pullets, while reducing P excretion in manure.

Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on growth performance and local innate immune response of broiler chickens challenged with Clostridium perfringens.

This study evaluated the effect of yeast-derived products on growth performance, gut lesion score, intestinal population of Clostridium perfringens, and local innate immunity of broiler chickens challenged with C. perfringens. One-day-old broiler chickens were randomly assigned to eight dietary treatments providing six replicate pens of 55 birds each per treatment. Dietary treatments consisted of Control diets without and with C. perfringens challenge, and diets containing bacitracin methylene disalicylate (BMD, 55 g/tonne), nucleotides (150 g/tonne), yeast cell wall (YCW, 300 g/tonne), and a commercial product Maxi-Gen Plus (1 kg/tonne) fed to chickens challenged with C. perfringens. Diets containing 10% distillers dried grains with solubles without and with C. perfringens challenge were also used. Birds were orally challenged with C. perfringens (10(8) colony-forming units (cfu)/bird) on day 14. On day 21, intestinal samples were collected for gene expression analysis. Pathogen challenge significantly (P < 0.05) impaired feed intake, body weight gain, and feed conversion ratio (FCR) shortly after the challenge (14-21 days). Increased C. perfringens counts and intestinal lesion scores were observed for challenged birds except the BMD-containing diet. Over the entire trial (1-35 days), no difference in growth performance was observed except the BMD diet which improved FCR over the Control, challenged group. Birds receiving nucleotides showed increased expression of toll-like receptors and cytokines interleukin (IL)-4 and IL-18 compared to the Control, challenged group. Expression of macrophage mannose receptor and IL-18 was upregulated in birds receiving YCW. Increased expression of cytokines and receptors involved in innate immunity in broilers receiving nucleotides and YCW suggests the immunomodulatory properties of these products under pathogen challenge conditions.

Effect of yeast-derived products and distillers dried grains with solubles (DDGS) on growth performance, gut morphology, and gene expression of pattern recognition receptors and cytokines in broiler chickens.

An experiment was carried out to investigate the effect of yeast-derived products and distillers' dried grains with solubles (DDGS) on growth performance, small intestinal morphology, and innate immune response in broiler chickens from 1 to 21 d of age. Nine replicates of 5 birds each were assigned to dietary treatments consisting of a control diet without antibiotic (C), and diets containing 11 mg/kg of virginiamycin, 0.25% of yeast cell wall (YCW), 0.2% of a commercial product Maxi-Gen Plus, 0.025% of nucleotides, 0.05% of nucleotides, or a diet containing 10% of DDGS. On d 21, 5 birds per treatment were euthanized and approximately 5-cm long duodenum, jejunum, and ileum segments were collected for intestinal morphology measurements. Cecal tonsils and spleen were collected to measure the gene expression of toll-like receptors TLR2b, TLR4, and TLR21, macrophage mannose receptor (MMR), and cytokines IFN-γ, IL-12, IL-10, and IL-4. No significant difference was observed for growth performance parameters. However, diets containing 0.05% of nucleotides and YCW significantly increased (P < 0.05) villus height in the jejunum. Furthermore, the number of the goblet cells per unit area in the ileum was increased (P < 0.05) in diets supplemented with yeast-derived products. The expression of TLR2b in the spleen was down-regulated for diets supplemented with nucleotides and antibiotic. In addition, lower expression of TLR21 and MMR was observed in the spleen of birds receiving yeast-derived products and antibiotic. However, expression of TLR4 in the spleen was up-regulated in diets supplemented with YCW and nucleotides. The expression of IFN-γ and IL-12 was down-regulated in the spleen of birds fed diets supplemented with yeast-derived products. In addition, inclusion of YCW, Maxi-Gen Plus, or 0.05% of nucleotides down-regulated the expression of IL-10 and IL-4 in the cecal tonsils. In conclusion, down-regulation of receptors and cytokines in spleen and cecal tonsils of birds fed diets supplemented with yeast-derived products may suggest that yeast products do not exert immune stimulating effect under normal health conditions.

The effect of phytase and fructooligosaccharide supplementation on growth performance, bone quality, and phosphorus utilization in broiler chickens.

An experiment was conducted to investigate the effects of phytase and 2 levels of fructooligosaccharide (FOS) supplementation on growth performance, bone mineralization, and P utilization of broiler chickens. A total of 210 day-old male broiler chickens (Ross) were randomly placed into 7 dietary treatments consisting of 6 replicates with 5 birds per pen. The experiment was designed as an augmented 2 × 3 factorial arrangement with 0 or 500 U/kg of phytase and 0, 0.5% or 1% of FOS added to a reduced Ca (0.8%) and available P (0.25%) negative control diet (NC). A positive control diet (PC) that contained 1% Ca and 0.45% available P was also included. During the entire experimental period, phytase supplementation significantly improved (P < 0.05) the feed conversion ratio (FCR), BW gain (BWG), and feed intake. Birds fed the PC diet showed significantly higher bone mineral density (BMD) and bone mineral content (BMC) in both femur and tibia bones (P < 0.0001) than those fed the NC diet. Phytase supplementation increased femur BMD (P < 0.05), whereas FOS decreased femur BMD and BMC (P < 0.05). Phosphorus utilization was significantly higher for the NC diet (P < 0.0001). Phytase alone and in combination with 0.5% FOS increased P utilization significantly when compared with other treatments (P < 0.05). Fructooligosaccharides, especially at the level of 0.5%, increased P retention. In conclusion, phytase supplementation in low Ca and P diets improved growth performance, bone quality, and P utilization. However, supplementing NC diets with phytase and FOS did not result in bone mineralization values comparable with that of the PC diet. The application of dietary FOS alone had a negative effect on broiler bone quality.

The effect of protease, amylase, and nonstarch polysaccharide-degrading enzyme supplementation on nutrient utilization and growth performance of broiler chickens fed corn-soybean meal-based diets.

A study was conducted to determine if amylase and protease addition would improve nutrient digestion during the first 2 wk of growth. The experimental treatments included a control corn-soybean meal-based diet and diets supplemented with either amylase or amylase plus protease. No effect of enzyme supplementation was observed on BW gain and feed conversion ratio. This was corroborated by similar ileal starch and protein digestibility values, which averaged 96.8, 96.8, and 96.9% and 83.9, 80.1, and 79.6%, respectively, for the control and for the amylase or amylase plus protease supplemented diets. Total tract digestibility of starch averaged 97.8, 97.7 and 97.7% for the 3 diets and was followed by a similar diet with AMEn values of 3,129, 3,129, and 3,106 kcal/kg. In another study, a 2(3) factorial arrangement of 8 dietary treatments was used to evaluate the effect of corn particle size (conventional or coarse vs. fine) and the addition of a nonstarch polysaccharide enzyme, amylase, or both on growth performance and nutrient utilization of broiler chickens from 1 to 21 d of age. Chickens fed a diet containing a conventionally ground corn (geometric mean diameter of 736 µm) showed higher (P < 0.001) BW gain (808 vs. 750 g/bird) and lower feed conversion ratio (1.27 vs. 1.32) than those consuming a fine corn-containing diet (geometric mean diameter of 482 µm). This was further substantiated by a lower AMEn content (2,852 vs. 2,972 kcal/kg). Addition of amylase had no effect on growth performance of chickens fed a conventional corn-containing diet, but improved BW gain, feed conversion ratio, and diet AMEn in those fed the finely ground corn, possibly due to increased starch digestion in the upper gut. Addition of nonstarch polysaccharide enzymes was effective for both diets, with the most pronounced effects observed in feed conversion ratio for the conventional corn-containing diet (1.27 vs. 1.23) and BW gain (750 vs. 789 g/bird) for the fine corn-containing diet. This was followed by the same magnitude of difference in diet AMEn content, which increased from 2,972 to 3,042 and 2,852 to 3,009 kcal/kg following enzyme addition.