Silicon Supplementation for Bone Health: An Umbrella Review Attempting to Translate from Animals to Humans.

Studies have attempted to demonstrate the benefits of silicon on bone health using a wide range of Si amounts-provided in the diet or through supplementation-and several different animal species. Previous studies in humans have also demonstrated a positive correlation between Si intake and bone health measures. The aim of the current review is to determine the effective levels of Si intake or supplementation that influence bone health to better inform future study designs and guidelines. Articles were identified using one of two search terms: "silicon AND bone" or "sodium zeolite A AND bone". Articles were included if the article was a controlled research study on the effect of Si on bone health and/or mineral metabolism and was in English. Articles were excluded if the article included human subjects, was in vitro, or studied silica grafts for bone injuries. Silicon type, group name, Si intake from diet, Si supplementation amount, animal, and age at the start were extracted when available. Dietary Si intake, Si supplementation amount, and the amount of Si standardized on a kg BW basis were calculated and presented as overall mean ± standard deviations, medians, minimums, and maximums. Studies that left out animal weights, amount of food or water consumed, or nutrient profiles of the basal diet were excluded from these calculations. Standardized Si intakes ranged from 0.003 to 863 mg/kg BW, at times vastly exceeding current human Si intake recommendations (25 mg/d). The lack of data provided by the literature made definitively determining an effective threshold of supplementation for skeletal health difficult. However, it appears that Si consistently positively influences bone and mineral metabolism by around 139 mg Si/kg BW/d, which is likely unfeasible to attain in humans and large animal species. Future studies should examine this proposed threshold more directly and standardize supplemental or dietary Si intakes to kg BW for better study replication and translation.

The Effect of Downhill Running on Quadriceps Muscle in Growth-Restricted Mice.

INTRODUCTION: Growth restriction (GR) reduces ribosome abundance and skeletal muscle mass in mice. A reduction in skeletal muscle mass increases the risk of frailty and is associated with high morbidity and mortality rates. As eccentric type exercise increases muscle mass, this investigation aimed to determine if eccentric loading of skeletal muscle via downhill running (DHR) increased muscle mass in GR mice. METHODS: Mice were growth-restricted either gestational undernutrition (GUN, n = 8 litters), postnatal undernutrition (PUN, n = 8 litters), or were not restricted (CON, n = 8 litters) via a validated cross-fostering nutritive model. On postnatal day (PN) 21, all mice were weaned to a healthy diet, isolating the period of GR to early life as seen in humans. At PN45, mice were assigned to either a DHR (CON, n = 4 litters; GUN, n = 4 litters; PUN, n = 4 litters) or sedentary (SED: CON, n = 4 litters; GUN, n = 4 litters; PUN, n = 4 litters) group. Downhill running (16% decline: 18 m·min -1 ) was performed in 30-min bouts, three times per week, for 12 wk on a rodent treadmill. At PN129, the quadriceps femoris was dissected and evaluated for mass, myofiber size and type, and molecular markers of growth. RESULTS: Following training, CON-DHR mice having larger cells than CON-SED, GUN-SED, PUN-SED, and PUN-DHR mice ( P < 0.05). The PUN group (as compared with CON) had reduced body mass ( P < 0.001), upstream binding factor abundance ( P = 0.012), phosphor-mTOR ( P < 0.001), and quadriceps mass ( P = 0.02). The GUN and PUN groups had increased MuRF1 abundance ( P < 0.001) compared with CON ( P < 0.001). CONCLUSIONS: The blunted response to training suggests GR mice may have anabolic resistance when exposed to eccentric type exercise.

Longitudinal effects of growth restriction on the murine gut microbiome and metabolome.

Undernutrition-induced growth restriction in the early stages of life increases the risk of chronic disease in adulthood. Although metabolic impairments have been observed, few studies have characterized the gut microbiome and gut-liver metabolome profiles of growth-restricted animals during early-to-mid-life development. To induce growth restriction, mouse offspring were either born to gestational undernutrition (GUN) or suckled from postnatal undernutrition (PUN) dams fed a protein-restricted diet (8% protein) or control diet (CON; 20% protein) until weaning at postnatal age of 21 days (PN21). At PN21, all mice were fed the CON diet until adulthood (PN80). Livers were collected at PN21 and PN80, and fecal samples were collected weekly starting at PN21 (postweaning week 1) until PN80 (postweaning week 5) for gut microbiome and metabolome analyses. PUN mice exhibited the most alterations in gut microbiome and gut and liver metabolome compared with CON mice. These mice had altered fecal microbial ß-diversity (P = 0.001) and exhibited higher proportions of Bifidobacteriales [linear mixed model (LMM) P = 7.1 × 10-6), Clostridiales (P = 1.459 × 10-5), Erysipelotrichales (P = 0.0003), and lower Bacteroidales (P = 4.1 × 10-5)]. PUN liver and fecal metabolome had a reduced total bile acid pool (P < 0.01), as well as lower abundance of riboflavin (P = 0.003), amino acids [i.e., methionine (P = 0.0018), phenylalanine (P = 0.0015), and tyrosine (P = 0.0041)], and higher excreted total peptides (LMM P = 0.0064) compared with CON. Overall, protein restriction during lactation permanently alters the gut microbiome into adulthood. Although the liver bile acids, amino acids, and acyl-carnitines recovered, the fecal peptides and microbiome remained permanently altered into adulthood, indicating that inadequate protein intake in a specific time frame in early life can have an irreversible impact on the microbiome and fecal metabolome.NEW & NOTEWORTHY Undernutrition-induced early-life growth restriction not only leads to increased disease risk but also permanently alters the gut microbiome and gut-liver metabolome during specific windows of early-life development.

Comparison of Bone Mineral Content of the Equine Third Metacarpal to Total Radiographic Bone Aluminum Equivalents From Unprocessed Digital Radiographs.

Digital radiographs are common for estimating bone mineral content (BMC) in horses with radiographic bone aluminum equivalents (RBAE). Processing algorithms are used to produce clearer images of digital radiographs in clinical settings, but this distorts RBAE. This study compared RBAE from digital radiographs to BMC from bone ash, and physical and digital morphology measurements. Digital radiographs were taken of six third metacarpals (MCIII) from equine cadavers with an aluminum step wedge penetrometer. A 2-cm transverse section of bone was digitally analyzed and excised from each MCIII. For each image, a linear regression was created using the step wedge thicknesses (R2 > 0.99) and used to obtain total and individual RBAE. Outer and inner diameters of both dorsal-palmar (DP) and lateral-medial (LM) aspects, as well as cortical thicknesses, were measured physically and digitally. Bone samples were ether-extracted, oven-dried, and ashed. Statistics were analyzed as correlations between variables. Physical and digital measurements of dorsal, medial, and lateral cortices, as well as DP outer diameter, tended to be similar (r > 0.74, P < .09) but palmar cortex measurements did not (r = 0.41, P = .42). The LM outer and DP/LM inner diameters were similar between the two methods (r > 0.95, P < .05). Total RBAE was strongly correlated to BMC (r > 0.93, P < .01). These results suggest that using digital radiographs to make morphological measurements is accurate and confirm the strong relationship between total RBAE and bone ash. However, this study emphasizes the need to use unprocessed radiographs for analysis.

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

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.

Low dietary silicon supplementation may not affect bone and cartilage in mature, sedentary horses.

As osteoarthritis is a major cause of lameness in horses in the United States, improving collagen health prior to onset and increasing collagen turnover within affected joints could improve health- and welfare-related outcomes. Through its positive effects on bone mineral content and density and its role in increasing collagen synthesis, silicon (Si) may slow the development and progression of osteoarthritis, thereby reducing lameness. This study evaluated the hypothesis that Si supplementation would increase cartilage turnover through increased collagen degradation and formation markers, as well as bone formation markers, resulting in reduced lameness severity when compared with controls. Ten mature Standardbred geldings were assigned to either a Si-treated (SIL) or control (CON) group and group-housed on pasture for 84 d. Horses were individually fed to ensure no cross-contamination of Si other than what was present in the environment. For the duration of the study, SIL horses received a Si-collagen supplement at the rate of 0.3 g supplement/(100 kg body weight day). Serum samples were taken weekly for osteocalcin, and plasma samples were taken on days 0, 42, and 84 for plasma minerals. On days 0, 42, and 84, subjective and objective lameness exams were performed, and radiographs and synovial fluid samples were taken from reference and osteoarthritic joints. Plasma minerals were similar in both groups and were lower on day 84 than on day 0 (P < 0.05). Si supplementation, fed at the manufacturer's recommended rate, did not improve lameness or radiographs when compared with controls, and supplemented horses did not show greater collagen degradation and/or synthesis markers in synovial fluid than controls, indicating that cartilage turnover remained unaffected. However, a minimum beneficial threshold and range for Si supplementation standardized to body weight need to be established.

Research Note: Bone ash from immature broilers correlates to bone mineral content calculated from quantitative computed tomography scans.

Owing to selection for rapid growth and heavy muscle, bone deformities and injuries in broiler chickens are common and present a welfare concern. Recently, clinical quantitative computed tomography scans (QCTs) have been used for laying hens with significant, strong correlations between QCT-generated bone mineral content (BMC), bone ash, and analytical calcium. The objectives of this study were to determine if QCT-generated bone mineral density of tibias and femurs correlated to fat-free ash and if analytical Ca could be correlated to bone ash and digitally calculated density in immature broilers. Male broilers (Ross 708, n = 125) were raised from day 1 after hatching, and at 42 D, right leg quarters were collected from 50 randomly selected birds and frozen at -20°C until analysis. Leg quarters were scanned with muscle and feathers intact and arranged in rows on plexiglass, and each QCT included a solid Ca hydroxyapatite phantom. Tibias and femurs were removed from leg quarters after autoclaving, ashed, and weighed. Pearson's correlation analysis was conducted to understand the association between analytical bone ash and QCT BMC while paired t tests determined the amount of difference between QCT BMC and ash. Ash weight was strongly correlated to QCT BMC in both the femur (R = 0.86, P < 0.001) and the tibia (R = 0.91, P < 0.001). The average difference between the amount of actual ash weighed and BMC calculated from the QCT was 0.03 ± 0.22 g (P = 0.3) for the femur and 0.04 ± 0.22 g (P = 0.2) for the tibia. This study confirms that this technique can supply invaluable skeletal health information without sacrificing birds.

Furosemide administration results in a transient alteration in calcium balance in mature horses.

Previous research documented that furosemide negatively impacted calcium balance for 3 days but did not determine when calcium balance returned to baseline. This study hypothesized that furosemide's impact on calcium would return to control values before 7 days post-administration. Ten mature geldings were assigned to either control (CON, n = 5) or treatment (FUR, n = 5) for the first of two 8-day total collections in crossover design. Treatment horses received one administration of furosemide (1 mg/kg, IV). A 10% sample of pooled faeces and urine from each day was kept. Calcium concentrations in hay, faeces and urine were determined by an atomic absorption spectrophotometer. Data were analysed using mixed-model-repeated measures ANOVA to determine influence of day and treatment. For urine output, FUR urinated twice as much during the 24 hr after administration than CON (p < .001). Horses in FUR excreted more urinary calcium 24-hr post-administration as compared to CON (9.3 ± 1.0 and 4.2 ± 1.0 g, respectively; p < .001). Calcium balance in FUR was more negative on day 1 than day 3 (p < .05). Faecal calcium concentrations remained the same from day 1 to day 7 in CON (6.3 ± 1.3 and 5.5 ± 1.3 g/kg, respectively; p > .10) but were lower in FUR on day 7 as compared to day 1 (4.8 ± 1.3 and 7.3 ± 1.3 g/kg, respectively; p < .001), indicating a potential mechanism to restore calcium balance. These findings corroborate previous studies on furosemide and calcium balance and provide evidence for a possible mechanism to recover net calcium losses after furosemide administration. Since calcium balance returns to baseline in 3 days and previous results have examined frequent, long-term use, furosemide may not negatively impact bone mineral content even if used over long periods.

Influence of Long-Term Furosemide Use on Bone Mineral Content, Bone Metabolism Markers, and Water Weight Loss in Horses.

Furosemide is used to reduce the incidence of exercise-induced pulmonary hemorrhage in racehorses. Previous research suggests furosemide negatively impacts calcium balance, which may have long-term implications for bone health. Eleven healthy horses, either control (CON, n = 5) or treatment (FUR, n = 6), were used to test furosemide's effects on bone mineral content (BMC), bone metabolism biomarkers, and weight loss after administration. Treatment horses received IV furosemide at 1 mg⋅kg-1 BW once weekly for seven weeks, and blood was collected before and at 24 hours after administration for biomarker analysis. All horses were weighed before and at 2, 4, 8, 24, and 48 hours after administration. Radiographs of the left third metacarpal were taken every 28 days for BMC determination using radiographic bone aluminum equivalence. After administration, FUR lost more BW than CON (P < .05 for all) as quickly as 2 hours after administration (CON: -0.4 ± 0.3%, FUR: -2.2 ± 0.3%), and these losses remained greater than CON at 4 hours (CON: -1.0 ± 0.3%, FUR: -3.3 ± 0.3%) and 8 hours (CON: 0.0 ± 0.3%, FUR: -1.2 ± 0.3%). FUR lost more BW on day 0 than CON (P = .03), but on day 28 and day 49, FUR BW losses were no greater than CON (P > .10). No treatment effects were observed for BMC nor pyridinoline and osteocalcin concentrations (P > .10). Reduced BW changes over time in FUR but not CON warrant further investigation to establish the efficacy of frequent furosemide administration over long periods of time.

Insulin Resistance as a Result of Body Condition Categorized as Thin, Moderate, and Obese in Domesticated U.S. Donkeys (Equus asinus).

Donkeys are often kept, especially in industrialized countries, as companion animals. Donkeys have greater digestive efficiency and tend to expend less energy than horses or ponies, which contributes to obesity in nonworking donkeys. Obesity in all equine species increases risk of chronic health conditions such as laminitis and insulin resistance. Previous studies in horses and ponies have documented obesity's potential effects on glucose-insulin dynamics with lower insulin sensitivity and higher insulin responses to glucose. However, limited studies on obesity and its health impacts in donkeys exist, so these effects on glucose-insulin dynamics have not been fully studied. Twenty-four donkeys were selected according to initial body condition score (BCS) and divided into three categories with eight donkeys in each: thin, moderate, and obese. A frequently sampled glucose-insulin tolerance test was performed with subsequent MINMOD analysis to determine the effects of BCS on glucose-insulin dynamics. Basal insulin was highest in obese donkeys when compared with moderate and thin donkeys (P = .02 and P = .01, respectively). There was an overall trend across groups for BCS to lower insulin sensitivity (P = .06). No other effect was found. Body condition score seems to affect donkeys in a similar manner to horses and ponies as higher BCS was associated with higher basal insulin and may lower insulin sensitivity. Higher basal insulin concentrations in obese donkeys could negatively influence health and contribute to serious, chronic conditions.

Influence of various concentrate-to-roughage ratios on dietary intake and nutrient digestibilities of weanling horses.

The objective of this study was to compare the feed intake and the apparent digestibilities of three different diets varying in concentrate-to-roughage ratios in weanling horses (n = 24) at 5 and 8 months of age. Horses were stratified by breed, gender, birth date and body weight and assigned to one of three dietary treatments containing the following concentrate-to-roughage ratios on an as-fed basis: 70:30 (High Con), 50:50 (Equal) and 30:70 (Low Con). All horses were fed their respective diets for a 10-day adaptation period and a 4-day collection period at 5 and 8 months. There were no differences in BW or daily feed intake among treatments during both trials. The horses consuming Low Con had a greater amount of faecal output than High Con at both 5 and 8 months (p < 0.01). At 5 months, High Con had the highest crude protein (CP) digestibility (p < 0.05). At 8 months, High Con had a higher CP digestibility than Low Con (p < 0.01) and tended to be higher than Equal (p = 0.07). Acid detergent fibre (ADF) digestibility did not differ among treatments; however, horses fed the Low Con tended to digest a higher percentage of neutral detergent fibre (NDF) than both the Equal and High Con treatments (p = 0.09). Horses in the High Con treatment tended to digest a higher percentage of energy than those in the Low Con treatment (p = 0.06). Weanlings seem to digest protein more thoroughly when fed high-concentrate diets and may digest fibre more efficiently when fed diets higher in fibre.