499 Late-Breaking: Impact of a High Calcium Diet in Growing Labrador Retriever Puppies

An important function of feeding large breed puppies is providing appropriate amounts of calcium and phosphorus, which is used in skeletal mineralization during growth. National Research Council stated calcium requirements are 0.8–1.2%, and phosphorus 1.0–1.6%. The objective of this study was to compare a high calcium diet (Ca: 5.7%; P: 2.9%) (Nature’s Logic Canine Beef Meal Feast; Nature’s Logic) (HC) to a normal control diet (Ca: 1.6%; P: 1%) (Purina Puppy Chow; Nestle Purina) (CON) in growing Labrador Retriever puppies. Thirty-two puppies (16 HC/16 CON) were used in two 10wk modified AAFCO large breed puppy growth trials. Body weights were measured weekly, feed intake daily, and digestibility, body composition, hematology, chemistry, and bone metabolism biomarkers were measured at 8wks, 13wks, and 18wks of age. All puppies passed all AAFCO large breed puppy growth requirements, including veterinary exams, body weight gain, and bloodwork parameters. Both groups had similar average weight gains from baseline to the end of the trial. No significant differences in bone mineral density were found between HC and CON groups at any timepoint. No significant differences were found between groups after baseline for parathyroid hormone, calcitonin, or tartrate resistant acid phosphatase bone metabolism biomarkers. Total tissue mass, fat mass, and lean mass were lower in the HC group compared to CON group (P < 0.05), likely due to lower caloric content and metabolizable energy in the HC diet than expected. Calcium digestibility was significantly higher in HC diet vs CON diet (P < 0.01). Based on this data, a high calcium diet had no negative impact on major physiological parameters in growing Labrador Retriever puppies.

No Observed Adverse Effects on Health Were Detected in Adult Beagle Dogs When Fed a High-Calcium Diet for 40 Weeks

The implications of long-term high calcium (Ca) intake are well documented in growing dogs and in adult dogs of large breed size, however, the consequences on other breeds and breed sizes are yet to be determined. Eighteen neutered adult beagles, nine males and nine females aged 1.4–4.4 years, were randomized to control or test diets providing in g∙4184 kJ−1 (1000 kcal−1): 1.44 and 7.19 total Ca balanced with 1.05 and 4.25 total phosphorus, respectively, for 40 weeks. Health parameters, ultrasound scans, radiographs, glomerular filtration rate, and mineral balance were measured at eight-week intervals. All dogs remained healthy with no measured evidence of orthopedic, urinary, or renal disease. The test diet resulted in a 5.2 fold increase in fecal Ca excretion. Apparent Ca digestibility (%) and Ca balance (g/d) did not significantly (p > 0.05) change from baseline in the test diet group, although dogs displayed a positive Ca balance (maximum at week 8, 1.11 g/d with 95% CI (0.41, 1.80)) before a neutral Ca balance was restored at week 32. Despite an initial positive Ca balance, we can conclude that no measurable adverse health effects were observed as a result of the test diet fed in this study in beagles over a period of 40 weeks.

Effect of Silicon Supplementation in Diets with Different Calcium Levels on Bone Mineral Metabolism and Bone Status in Growing Female Rats

Objectives Silicon is important for the growth and development of bone and connective tissues. However, few studies have investigated effects of silicon supplementation on bone metabolism on growing females. We evaluated the effect of silicon supplementation on bone mineral metabolism and bone status in growing female rats fed diet with different calcium levels. Methods Sixty 6-wk-old Sprague-Dawley female rats were divided into 6 groups and fed diet with different levels of calcium (0.1%, 0.5%, 1.5%) and silicon (5 ppm, 500 ppm) for 10 weeks. We used a two-way ANOVA test to examine the difference and a significant level was set at P < 0.05. Results Silicon retention significantly increased by silicon supplementation and significantly decreased by high calcium diet (1.5%). Mg retention significantly decreased by high calcium diet. Serum calcium and silicon contents were not significantly different among the 6 groups. Low calcium diet (0.1% calcium) significantly increased serum osteocalcin and C-telopeptide cross-links of type I collagen (CTX) levels, and silicon supplementation significantly decreased CTX levels in the low calcium diet group. Bone mineral density was significantly increased along with greater calcium level in the diet, but was decreased by silicon supplementation in the high calcium diet. Rats in the 0.5% calcium diet group had significant increase in strength of the tibia by silicon supplementation. Conclusions According to our findings, the effect of silicon supplementation on bone metabolism may differ according to the calcium intake levels in growing females. Although further research is needed, when supplementing silicon to improve bone health in growing females, the calcium intake level should be considered. Funding Sources Korea Research Foundation.

PROLONGED EXPOSURE TO DIFFERENT TYPES OF ENERGY RESTRICTED CALCIUM DIET MODULATES THE INFLAMMATORY AND OXIDATIVE STRESS RESPONSE IN HEALTHY MALE RATS

Objective: Emerging evidence established the role of dietary calcium in the modulation of obesity. Obesity is known to induce inflammatory and oxidative stress in adipocytes resulting in several metabolic complications. In the present study, we evaluated the role of low and high calcium diet on systemic inflammatory response and oxidative stress markers in both plasma and hepatic tissues in male rats. Methods: A total of 30 male rats were divided into three groups and fed with control, low calcium (0.25%), and high calcium (1.0%) diet for 3 months. All the diets were isocaloric in nature. At the end of the treatment, all rats were sacrificed, followed by collection of blood and hepatic tissue for inflammatory, oxidative, antioxidant, and histological study. Results: Rats fed with a low calcium diet showed a significant increase in the body weight gain, liver mass, plasma inflammatory markers C-reactive protein, interleukin-6, and tumor necrosis factor-alpha. Low calcium diet significantly increased the lipid peroxidation and protein carbonylation and decreased the superoxide dismutase and glutathione peroxidase activities in both plasma and liver. High calcium diet, on the other hand, showed the reversed effect. Conclusion: Low calcium in the diet, along with obesity, increases the systemic inflammatory response, which in turn increases oxidative stress both in blood and hepatic tissues. This might be associated with obesity-induced hepatic disorder. High calcium in diet attenuates this effect.