APSS 2013 Proceedings - The University of Sydney

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Aust. Poult. Sci. Symp. 2013.....24 CALCIUM / AVAILABLE PHOSPHORUS RATIO AND CARBOHYDRASE / PHYTASE AFFECT BROILER PERFORMANCE A. PREYNAT 1 , G. UZU 2 , C. PICART 3 , Y.G. LIU 4 and P.M. DALIBARD 1 Summary The objective of this work was to study the impact of several calcium/available phosphorus ratios (Ca/aP) on broiler performance with or without addition of a carbohydrases/phytase complex (Rovabio ® Max LC). Four thousand eight hundred 1-day old chicks (Ross PM3) were allocated into 6 treatments: 3 control diets with low levels of aP (0.25% for starter and 0.20% for grower) and different Ca/aP ratios from high (T1: 3.8 for starter and 4.2 for grower), medium (T2: 3.3 and 3.7) and low (T3: 2.8 and 3.2) obtained by changing calcium levels. Each control diet was supplemented with Rovabio ® Max LC, 200 ml/t (T4 to T6). Each treatment was composed of 8 pens of 100 males. Feed consumption, weight gain and litter quality were measured at 21 and 34d. Results showed that lowering Ca/aP ratio reduced the negative impact of aP deficiency by increasing significantly live weight (+153 and 276g for the medium and low ratios, respectively, in comparison to the high ratio) and feed intake (+247 and 439g), with no effect on feed conversion ratio (FCR). At 21d this reduction in the Ca/aP ratio significantly improved litter score, but this effect faded away during the grower phase on day 34. The addition of the enzyme significantly improved growth performance parameters, excepted for FCR. The best performances were obtained with the diets with the lowest Ca/aP ratio and supplemented with the enzyme. Overall, the enzyme addition showed no impact on litter quality, except that the high Ca/aP ratio diet(T4(T1+E) produced a significant degradation in litter quality compared with all other diets In conclusion, high calcium levels accentuated the impact of low available phosphorus diets on broiler performance. The enzyme combination significantly improved growth performance of birds fed on low phosphorus diets and reduced the differences due to Ca/aP ratios. The results suggest that the formulation for a low level of dietary phosphorus requires a simultaneous reduction of dietary calcium level. I. INTRODUCTION Optimisation of phosphorus (P) supply in animal feed remains a major environmental and economical challenge. In this context, nutritional strategies have been developed to limit P overfeeding and excretion, relying on a better adjustment of P supply to meet requirement and improving P availability through introduction of exogenous phytase (Selle and Ravindran, 2007). Nevertheless, low P diets can severely impact growth performance and percentage bone ash in young broilers (Waldroup et al., 1963; Nelson et al., 1965). Overall, P utilisation is governed by digestive and metabolic efficiency, in which several dietary components such as calcium (Ca) and vitamin D play important roles. Increasing the level of dietary Ca beyond dietary requirements or widening the ratio of dietary Ca to P is often associated with a decrease in broiler performance, mineral retention and phytate disappearance (Edwards, 1982). Vitamin D effectively improves the retention of dietary Ca and P of broiler chick diets. As a result, balance among this element might affect animal performance (Létourneau Montminy et al., 2008). However, dietary P reduction can be 1 Adisseo France S.A.S. Antony, France. 2 Consultant, Saint Hilaire, France. 3 In-vivo NSA, Saint Nolff, France. 4 Adisseo Asia Pacific P/L, Singapore. 64
Aust. Poult. Sci. Symp. 2013.....24 achieved without deleterious effects on performance and bone mineralization if Ca is reduced simultaneously (Driver et al., 2005; Rama Rao et al., 2006). Therefore, it is very important to take into account the Ca/P ratio, particularly when phytase is added to the diet. Driver et al. (2005) clearly demonstrated that animals perform better when phytase is added to low P diets with Ca/total P ratio of 1.1 to 1.4 rather than 1.7 to 2.0, whereas Letourneau-Montminy et al. (2008) observed the highest growth rate when broilers were fed a diet with a Ca/total P ratio of 0.9. Although many studies suggest reductions of dietary Ca level in phytase supplemented broiler diets may be warranted, appropriate dietary Ca level and Ca/P ratio still require more precise definitions. The present study was carried out to assess the effect of several Ca/aP on broiler performance in chicks given wheat-based diets with or without a carbohydrolases/ phytase complex. II. MATERIALS AND METHODS Four thousand eight hundred 1-day old chicks (Ross PM3) were allocated into 6 treatments: 3 control wheat-based diets with low levels of aP (0.25% for starter and 0.20% for grower, respectively) and different Ca/aP ratios: high (T1: 3.8 for starter and 4.2 for grower), medium (T2: 3.3 and 3.7) and low (T3: 2.8 and 3.2) obtained by changing calcium levels. Each control diet was supplemented with Rovabio ® Max (Adisseo, Antony, France) (T4(T1+E), T5(T2+E), T6(T3+E)). Each treatment was composed of 8 pens of 100 males. The main characteristics of diets are presented in Table 1. The enzyme was sprayed on diets after pelleting (200 ml/mt). The enzyme activities of diets were controlled by laboratory analysis (Adisseo). Feed consumption, live weight gain and litter quality were measured at days 21 and 34. Litter score were ranged from 1 to 5 corresponding to bad and good litter quality, respectively. Mortality rate was recorded. Results were tested with a variance analysis using “t” test to compare the different diets, with and without enzyme supplementation. Least square means and standard errors of the means are reported. III. RESULTS AND DISCUSSION All xylanase and phytase activities measured in supplemented diets were in line with the standard recommendation (xylanase: 1,100 visco units/kg and phytase: 500 FTU units/kg). The average mortality rates were 3.3, 3.4, 3.4, 2.0, 3.1 and 3.1% for treatments T1, T2, T3, T4(T1+E), T5(T2+E) and T6(T3+E), respectively. There were no significant differences among treatments and no birds were eliminated due to leg problems (data not shown). Growth performance is presented in Table 2. For the complete growth period (0-34d) of the three control diets, lowering Ca/aP ratio linearly reduced the negative impact of the low aP diets in that body weight increased by 153 and 276g for the medium and low ratios, respectively. In comparison to the high ratio, feed intake increased 247 and 439g, with no effect on feed conversion ratio. Performances achieved were below genetic provider average for all parameters (Aviagen, 2012). Average (min-max) relative difference among control diets and standard performance were 20 (14 - 21), 58 (55 – 61) and 10 (10 – 11) for final body weight, daily weight gain and feed conversion ratio, respectively. This effect might be partly explained by phosphorus depletion in experimental diets and ratio Ca/aP above the recommendation. The enzyme supplementation of T1, T2 and T3 diets significantly improved the zootechnical parameters and resulted in higher body weight, weight gain and feed intake than those of the respective control diets (P ≤ 0.001). However, no effect was observed on feed conversion following the enzyme addition. No interaction was observed between enzyme effect and dietary Ca/aP (P > 0.05). Moreover, it is important to note that the best 65
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24 th ANNUAL AUSTRALIAN POULTRY SCI
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AUSTRALIAN POULTRY SCIENCE SYMPOSIU
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AUSTRALIAN POULTRY AWARD The Austra
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CONTENTS THE IMPORTANCE OF THE POUL
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SHORT COMMUNICATION SESSION # 1: (c
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SHORT COMMUNICATION SESSTION # 2: (
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HOT TOPIC 2: EMERGING DISEASES AND
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Aust. Poult. Sci. Symp. 2013.....24
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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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