Effect of Organic Acids and Prebiotics on Bone Quality in Laying Hens Fed Diets with Two Levels of Calcium and Phosphorus

Abstract

In an experiment conducted on caged Bovans Brown hens, the effect of diet supplementation using organic acids and prebiotic fructans on the biomechanical and geometrical indicators of the tibia and femur bones was evaluated. At 25 weeks of age, layers were randomly assigned to 14 experimental groups, each comprising 6 hens kept in individual cages. A 2 × 7 factorial arrangement, with two dietary levels of calcium and phosphorus (normal – 37.0 g Ca/kg, 6.5 g P/kg, and reduced – 32.5 g Ca/kg, 6.0 g P/kg), and with diets supplemented by selected additives (none; inulin, 7.5 g/kg; oligofructose, 7.5 g/kg; short chain fatty acids (SCFA), 5.0 g/kg; medium chain fatty acid (MCFA), 2.5 g/kg; SCFA, 3.0 g/kg + MCFA, 2.0 g/kg; inulin, 3.0 g/kg + SCFA, 5.0 g/kg) was used. The experiment was conducted for 45 weeks and concluded when the hens were 70 weeks old. At 70 weeks of age, reducing the dietary levels of Ca and P had decreased the bone breaking strength by 8.9% (P ≤ 0.001) and the yielding load by 5.6% (P ≤ 0.05). A similar tendency for bone breaking strength (P ≤ 0.05) and stiffness (P ≤ 0.05) was found in the femur bones. The diet with a lower level of Ca and P negatively affected the geometrical indicators of the bones such as cortex thickness (P ≤ 0.05) and cross section area (P ≤ 0.05), but had no effect on bone weight and length. Hens fed diets supplemented with oligofructose, MCFA, SCFA + MCFA or inulin + SCFA displayed a significantly higher bone breaking strength and yield load in the tibia bone than that of the control group. In the case of femurs, a positive influence of MCFA or simultaneous addition of inulin + SCFA on bone breaking strength was found. The additives had no significant effects on the geometrical indicators of either bone. It was concluded that selected feed additives which lower the pH of the diet and intestinal content can beneficially affect the biomechanical indicators of the bones of high-productive laying hens. Laying hens, bone quality, calcium, organic acids, prebiotic fructans Symptoms of osteoporosis are often observed in modern flocks of high-productive layers, especially in the second part of the laying cycle. Osteoporosis can be defined as a decrease in the fully mineralized structural bone in which Ca is mobilized from the bone in order to contribute to eggshell formation (Whitehead and Fleming 2000). The condition leads to increased bone fragility and susceptibility to fracture. The consequences of this syndrome, also known as ‘cage layer fatigue’, i.e., poor bone quality, weakness, deformities and breakage, spinal bone collapse and paralysis, can be an important welfare problem, causing acute and chronic pain and distress to the birds (Webster 2004). In the United Kingdom, it was found that, in the end phase of lay, 29% of caged hens had sustained one or more broken bones during their lifetime (Gregory and Wilkins 1989). A study conducted by McCoy et al. (1996) attributed 35% of mortality in commercial caged laying hens to osteoporosis. Bone breakage is also a serious problem during the catching and transport of hens prior to slaughter, and during processing, which reduces the marketability of spent caged layers (Gregory and Wilkins 1989). Results of the study carried out by Jendral et al. (2008) indicate that hens caged in conventional cages, where the opportunity for movement and load-bearing exercises is limited, are particularly vulnerable to osteoporosis, exhibiting lower tibia and femur mineral density, bone mass, cortical bone area and mass and bone ACTA VET. BRNO 2010, 79: 185-193; doi:10.2754/avb201079020185 Address for correspondence: Doc. dr hab. Sylwester Świątkiewicz National Research Institute of Animal Science Department of Animal Nutrition and Feed Science ul. Krakowska 1, 32-083 Balice, Poland Phone: +48 666 081 343 Fax: +48 122 856 733 E-mail: sylwester.swiatkiewicz@izoo.krakow.pl http://www.vfu.cz/acta-vet/actavet.htm breaking strength than those kept in furnished colony cages, or cages modified with a nest box and perch. Optimization of nutrition is one of the strategies for prevention of osteoporosis in hens. Because of the high demand for Ca in highly producing layers, the supply of an adequate amount of this macroelement in the diet is the most important nutritional factor influencing bone quality. Use of particulate limestone, as compared to fine particle CaCO3, as a source of Ca for hens was of benefit to bone strength and structure (Koreleski and Świątkiewicz 2004; Fleming 2008). In our earlier experiment, supplementation of the diet with 25-hydroxycholecalciferol, active metabolite of vitamin D3 (25-OH-D3), which is necessary for the hen’s proper Ca metabolism, was also shown to have a positive effect on selected mechanical properties of tibia bones (Świątkiewicz and Koreleski 2005). The results of several studies carried out on rats have indicated that by lowering intestinal pH, such additives as organic acids or prebiotic fructans (inulin, oligofructose) had a beneficial effect on Ca absorption (Lutz and Scharrer 1991; Delzenne et al. 1995; Ohta et al. 1995; Morohashi et al. 1998; Demigne et al. 2008), bone mineralization (Roberfroid et al. 2002; Kruger et al. 2003; Zafar et al. 2004; Nzeusseu et al. 2006; Demigne et al. 2008) and bone architecture measured as the femoral bone volume (Takahara et al. 2000). Sacakli et al. (2006) indicated that the addition of short chain organic acids (lactic + formic acid) to the diet for quail improved utilization of dietary phosphorus and increased the content of crude ash in tibia bones. Inulin or organic acids added to the diet for broilers increased the length of intestinal villus (Rehman et al. 2007; Senkoylu et al. 2007), which might stimulate the absorption of minerals. The aim of the experiment was to study the effect on the biomechanical and geometrical properties of tibia and femur bones when short (SCFA), or medium chain fatty acids (MCFA), or prebiotic fructans with different lengths of chain (inulin or oligofructose) are added to the layer’s diet at different levels of Ca and P. Materials and Methods The Local Krakow Ethics Committee for Animal Experiments gave its approval to all the experimental procedures relating to the use of live animals. Eighty-four, 18-week-old Bovans Brown hens, obtained from a commercial source, were placed in individual cages, on a wire-mesh floor under controlled climate conditions in the poultry house at the Experimental Station of the National Research 186 Table 1. Composition of experimental diets in g/kg Ingredients Control Reduced level of Ca and P

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Cite this paper

@inproceedings{witkiewicz2010EffectOO, title={Effect of Organic Acids and Prebiotics on Bone Quality in Laying Hens Fed Diets with Two Levels of Calcium and Phosphorus}, author={Sylwester Świątkiewicz and Jerzy Koreleski and Anna Arczewska}, year={2010} }