Silicon supplementation affects mineral metabolism but not bone density or strength in male broilers

PLOS ONE RESEARCH ARTICLE Silicon supplementation affects mineral metabolism but not bone density or strength in male broilers Abby Pritchard ID*, Cara Robison, Tristin Nguyen, Brian D. Nielsen Department of Animal Science, Michigan State University, East Lansing, Michigan, United States of America * a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Pritchard A, Robison C, Nguyen T, Nielsen BD (2020) Silicon supplementation affects mineral metabolism but not bone density or strength in male broilers. PLoS ONE 15(12): e0243007. https://doi.org/10.1371/journal. pone.0243007 Editor: Michael H. Kogut, USDA-Agricultural Research Service, UNITED STATES Received: July 27, 2020 Accepted: November 12, 2020 Published: December 7, 2020 Copyright: © 2020 Pritchard et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Because leg injuries produce welfare concerns and impact production for broilers, numerous interventions have been suggested as potential solutions. One mineral which may affect bone quality is silicon. The objective of this study was to determine if supplementing bioavailable silicon could affect bone morphology, mineralization, and strength without negatively influencing welfare and meat quality. Male broilers were raised from d 1 after hatching until 42 d of age and randomly assigned to treatment groups for silicon supplementation in water: Control (no supplement, C; n = 125), Normal (0.011 ml supplement/kg bodyweight, N; n = 125) and High (0.063 ml supplement/kg bodyweight, H; n = 125). Toe damage, footpad dermatitis, hock burn, and keel blisters were assessed on d 42. Blood samples were collected from wing veins for serum osteocalcin, pyridinoline cross-links, and mineral analysis. Clinical QCT scans and analysis were conducted immediately before four-point bending tests of tibias. Texture analysis was performed on cooked fillets. Silicon supplementation tended to increase daily water consumption in N and H as compared to C (P = 0.07). Footpad dermatitis and hock burn scores were higher in H than in N or C (P < 0.05 for both comparisons). Supplementation altered serum minerals (P < 0.001), but bone density, morphology, and strength measures were similar among groups. The highest level of supplementation in the current study on a kg bodyweight basis was above recommended intakes but below previous amounts demonstrating silicon’s positive influence on bone, indicating that previously suggested minimum thresholds need to be reevaluated. Factors such as growth rate and mechanical loading likely play a greater role in developing bone quality than trying to supplement on top of good basic nutrition alone. Data Availability Statement: All relevant data are within the manuscript. Funding: This project was funded as part of a grant awarded to B.D.N. from the Michigan Animal Agriculture Alliance (M-AAA-18-010). M-AAA provided support in the form of salary for author A. P. but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The supplement included in research materials was provided by Agro-Solutions, but this funder did not Introduction Nearly 20 million metric tons of broiler meat per year are produced by the United States alone [1]. Due to genetic selection, commercial broiler chickens have rapid growth rates and high feed efficiency. As producers seek to increase production while reducing costs, birds will grow from about 40 g a day after hatching to around 3 kg in 42 days. This fast growth generates problems, ranging from pulmonary hypertension and sudden death syndrome [2] to leg PLOS ONE | https://doi.org/10.1371/journal.pone.0243007 December 7, 2020 1 / 16 PLOS ONE have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Competing interests: This project was funded as part of a grant awarded to B.D.N. from the Michigan Animal Agriculture Alliance (M-AAA-18010). M-AAA provided support in the form of salary for author A.P. but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The supplement included in research materials was provided by AgroSolutions, but this funder did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. These commercial affiliations do not alter our adherence to PLOS ONE policies on sharing data and materials. Silicon supplementation in broilers deformities and fractures [3]. Because these birds have been selected for muscle gain and size, this selection creates a high muscle to bone ratio which puts additional strain on their legs. The fast growth also negatively impacts bone quality by increasing bone porosity [4] and decreasing ash and breaking strength per kg bodyweight [4, 5]. In addition to injuries and deformities, hock burns, keel blisters, and footpad dermatitis can cause additional pain, thereby reducing weight gain and efficiency, and may affect nearly 50% of birds in commercial operations [6, 7]. Because leg injuries produce welfare concerns and impact production [8, 9], numerous interventions have been suggested as potential solutions, many of which have aimed at improving bone mineral density (BMD). Because bone typically responds to loading [10], attempts at encouraging movement have been employed such as: adding perches [11], reducing stocking density [12], and increasing the photoperiod [13]. These methods have not convincingly improved leg health [14, 15] and have not been implemented in commercial systems. Frequently, changes to nutrition have been suggested, as feed is easier to manipulate than changes to the environment. Reducing metabolizable energy [16] or limiting overall feed intake [4] can improve bone quality by slowing growth rate, but producers do not want slowed growth. Varying concentrations and sources of calcium and other minerals [16–18] have positively influenced bone mineral content (BMC), BMD, and breaking strength. By manipulating these minerals, growth rate remains the same, but potential leg problems may be averted. One mineral which may affect bone quality is silicon. Older studies showed that silicon deficiency in chicks and rats produces more porous, less mineralized bone [19–21]. Silicon intake in humans has been linked to greater BMD [22–24] and, in other species, silicon can increase bone formation markers such as osteocalcin [23] and reduce bone resorptio (...truncated)