APSS 2013 Proceedings - The University of Sydney

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Aust. Poult. Sci. Symp. 2013.....24 EFFECTS OF LOW CALCIUM AND AVAILABLE PHOSPHORUS DIETS ON PERFORMANCE, SKELETAL CHARACTERISTICS, AND WELFARE PARAMETERS OF ROSS-308 MALE BROILERS L.B. LINARES 1 , S.M. CARROLL 1 , M.A. SILVA 1 , J.T. HALLEY 1 and C. FISHER 1 The aim of this trial was to investigate the effect of lowering dietary calcium (Ca) and available phosphorus (av.P) during Starter (0 to 10d), Grower (11 to 24d) and Finisher (25 to 45d) phases on performance of 4416 Ross-308 male broilers. Diets were wheat-soybean meal, corn gluten meal based, and no phytase added. Birds received one of two dietary Starter treatments: 1.13% Ca; 0.50% av.P or 1.03% Ca; 0.45% av.P. At 10 days, birds were assigned to a Grower/Finisher treatment as part of a central composite design (CCD). The CCD used a combination of one of five dietary Grower treatments (0.64% to 1.04% Ca; 2.2:1 Ca:av.P) with one of five Finisher treatments (0.58% to 0.99% Ca; 2.2:1 Ca:av.P) creating 12 runs (8 treatments + 4 centre points) with 8 replicates per run arranged according to each of the Starter treatments. Daily 23-hrs light was provided up to day 7, and 18-hrs light until depletion. Birds were brooded at 32 o C, with temperature gradually reduced to 20 o C at 27d, and remained at this level until depletion. Liveweight (LW) and mortality adjusted FCR (FCR adj ) were recorded on days 10, 24, 32, 39 and 45. For lixiscope (x-ray) bone evaluation, five and four average weight live birds/pen were selected on days 26 and 40, respectively. These birds were also evaluated for any visual leg defects, incidence and severity of hock burn and foot pododermatitis (FPD) at both ages. At 39 days, five average weight birds/ pen were processed and carcass characteristics were recorded. At 10 days, there was no significant effect of dietary treatment on LW or livability. The FCR adj at day 10 was significantly improved (P < 0.001) by lowering dietary Ca (1.020 vs. 1.009). There was a significant linear response to increasing dietary Ca in the Grower phase for 24 day LW (mean 1248.1g P < 0.01) and FCR adj (mean 1.359; P < 0.006). Dietary treatment had no significant effect on lixiscope scores, incidence of leg defects or FPD at day 26. There was a significant linear response to lowering Ca levels in Grower diets on incidence and severity of hock burn (P < 0.01) at 26 days. There was no significant effect of dietary treatment (P > 0.05) on 32 day LW (mean 2041.3g). At 32 days FCR adj (mean 1.498) was improved linearly by increasing Ca levels during Grower period only (P < 0.013). At 39 days, LW (mean 2803.1g) increased linearly by increasing Ca levels in the Finisher period (P < 0.004) and there was a positive Grower x Finisher diet interaction (P < 0.003). However, FCR adj (mean 1.594) was unaffected (P > 0.05) at this time point. At 39 days there was a positive linear response in 0.04% of eviscerated carcass yield (mean 70.85%; P < 0.02), by increasing dietary Ca in Finisher phase. Neither Grower nor Finisher dietary treatment had a significant effect on lixiscope analysis or leg defects at 40 days. However, there was a linear response to lowering Ca in Grower diets resulting in a reduction in severity of hock burn (P < 0.05). At 45d, LW (mean 3528.5g) and FCR adj (mean 1.606) were not affected by the treatments (P > 0.05). In conclusion, when using a Starter diet with higher content of calcium it is possible to adopt intermediate dietary levels of Ca in Grower (~0.80%) and Finisher (~0.70%) phases to 45 days without compromising broiler performance or skeletal characteristics. Keywords: broiler, low calcium, low phosphorus, performance, skeleton 1 Aviagen Limited, Newbridge, EH28 8SZ, Scotland, UK. llinares@aviagen.com 18
Aust. Poult. Sci. Symp. 2013.....24 INTERACTION BETWEEN DIETARY PHYTASE, CALCIUM AND DIGESTIBLE PHOSPHORUS LEVELS ON PERFORMANCE AND TIBIA ASH IN BROILERS A. SACRANIE 1 , T. VAN GERWE 1 , J. DE LOS MOZOS 1 , A. GUTIERREZ DEL ALAMO 1 , A.J. COWIESON 2 and H. ENTING 3 Summary A broiler study was conducted for 36 days with eight treatment groups in a 2 phytase x 2 calcium (Ca) level x 2 digestible phosphorus (dP) level experimental design. Birds exposed to diets low in Ca, and standard in dP performed the best while the high Ca treatments induced negative responses, especially in the first 8 days of experimentation. It was concluded that the level of dP release from the high phytase inclusion was overestimated, while the higher Ca levels included in the study impeded phosphorus (P) digestibility and bone development. I. INTRODUCTION The global availability of inorganic phosphates is limited; phosphorus (P) is the third most expensive ingredient after energy and amino acids. Therefore sustainable animal production requires optimal utilisation of P to reduce the cost of feeding. Over two thirds of P in plantbased feedstuffs is not readily available in poultry as it is bound to phytic acid (PA), which has been commonly thought to be due to the low levels of endogenous phytase (Bedford, 2000; Woyengo and Nyachoti, 2011). However, recent studies have suggested that this is not the case, and in fact chickens possess adequate phytase activity in the intestinal mucosa. The primary issue with phytate digestion is poor substrate solubility in the small intestine due to cation (mainly Ca) interactions (Maenz and Classen, 1998; Cowieson, et al., 2011b). Calcium is known to form insoluble complexes with phytate phosphorus (PP), which hinders phytase activity (Angel, et al., 2002). Therefore, lowering dietary Ca levels can further improve the effect of exogenous phytase on PP degradation. Recent studies have shown that when adding phytase (500 FTU/kg), while at the same time lowering Ca in starter diets from 1% to 0.67% in combination with reduced non-PP (nPP) levels does not impair young bird performance (Létourneau-Montminy, et al., 2010; Powell, et al., 2011). The use of exogenous phytase to assist the bird in degrading PP has become common practice. In recent years, the use of higher levels of exogenous phytase, referred to as super dosing, has been increasingly promoted as a method to release more PP and to alleviate the antinutritive effects of phytate per se (Cowieson, et al., 2011b). In this study, the interaction between dP, Ca and phytase levels was evaluated with the aim of lowering inclusions of inorganic phosphates by optimising the hydrolysis of PP. II. MATERIALS AND METHODS Three thousand two hundred male Ross 308 broiler chickens were randomly distributed amongst 80 pens, 40 birds per pen, giving 8 treatments with 10 replicates. Each pen, 2.5 x 1.6 m, was fitted with 1 feeder and 4 nipple cup drinkers. Birds had ad libitum access to feed and water. From 0-3d, birds had 24 hours of light and from then on 18 hours of light and 6 hours of darkness. At the start of the trial brooding temperature was set to 33°C and then reduced incrementally to 20°C by 29 days. A description of treatments is shown in Table 1. A 3 phase 1 Poultry Research Centre, Nutreco R&D, Toledo, Spain. 2 Poultry Research Foundation, University of Sydney, Camden, NSW 2570, Australia. 3 Application and Solution Centre, Nutreco, Boxmeer, Netherlands. 19
Page 1 and 2: 24 th ANNUAL AUSTRALIAN POULTRY SCI
Page 3 and 4: AUSTRALIAN POULTRY SCIENCE SYMPOSIU
Page 5: AUSTRALIAN POULTRY AWARD The Austra
Page 9 and 10: CONTENTS THE IMPORTANCE OF THE POUL
Page 11 and 12: SHORT COMMUNICATION SESSION # 1: (c
Page 13 and 14: SHORT COMMUNICATION SESSTION # 2: (
Page 15: HOT TOPIC 2: EMERGING DISEASES AND
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INTERACTIVE EFFECTS OF EXOGENOUS EN
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microbiota to favor an increased ac
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AUTHOR INDEX Name Page(s) Email Add
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Klein-Hessling, H 207 hkleinhesslin
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Van de Wouw, A 247 nnet.vandewouw@w
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