Osteochondrosis in fetuses of ewes overfed calcium

Response of cattle with clinical osteochondrosis to mineral supplementation

Since 1982, farmers in the North West province and other parts of South Africa have noticed an increase in the incidence of lameness in cattle. Macro- and microscopical lesions of joints resembled osteochondrosis. Pre-trial data indicated that cattle with osteochondrotic lesions recovered almost completely when fed a supplement containing bio-available micro- and macrominerals of high quality. In the present trial, 43 clinically affected cattle of varying ages (1-5 years) and sexes were randomly divided into three groups. Each group was fed the same commercial supplement base with differing micro- and macromineral concentrations to determine the effect of mineral concentrations on the recovery from osteochondrosis. Both supplements 1 and 2 contained 25% of the recommended National Research Council (NRC) mineral values. Additional phosphate was added to supplement 2. Supplement 3, containing 80% of the NRC mineral values, was used as the control. Results from all three groups indicated no recovery from osteochondrosis. Urine pH of a small sample of the test cattle showed aciduria (pH < 6). Supplement analysis revealed addition of ammonium sulphate that contributed sulphate and nitrogen to the supplement. Supplementary dietary cation anion difference (DCAD) values were negative at -411 mEq/kg, -466 mEq/kg and -467 mEq/kg for supplements 1, 2 and 3, respectively, whereas the pre-trial supplement was calculated at +19.87 mEq/kg. It was hypothesised that feeding a low (negative) DCAD diet will predispose growing cattle to the development of osteochondrosis or exacerbate subclinical or clinical osteochondrosis in cattle.

Maternal Dietary Supplementation with Oligofructose-Enriched Inulin in Gestating/Lactating Rats Preserves Maternal Bone and Improves Bone Microarchitecture in Their Offspring

Nutrition during pregnancy and lactation could exert a key role not only on maternal bone, but also could influence the skeletal development of the offspring. This study was performed in rats to assess the relationship between maternal dietary intake of prebiotic oligofructose-enriched inulin and its role in bone turnover during gestation and lactation, as well as its effect on offspring peak bone mass/architecture during early adulthood. Rat dams were fed either with standard rodent diet (CC group), calcium-fortified diet (Ca group), or prebiotic oligofructose-enriched inulin supplemented diet (Pre group), during the second half of gestation and lactation. Bone mineral density (BMD) and content (BMC), as well as micro-structure of dams and offspring at different stages were analysed. Dams in the Pre group had significantly higher trabecular thickness (Tb.Th), trabecular bone volume fraction (BV/TV) and smaller specific bone surface (BS/BV) of the tibia in comparison with CC dams. The Pre group offspring during early adulthood had an increase of the lumbar vertebra BMD when compared with offspring of CC and Ca groups. The Pre group offspring also showed significant increase versus CC in cancellous and cortical structural parameters of the lumbar vertebra 4 such as Tb.Th, cortical BMD and decreased BS/BV. The results indicate that oligofructose-enriched inulin supplementation can be considered as a plausible nutritional option for protecting against maternal bone loss during gestation and lactation preventing bone fragility and for optimizing peak bone mass and architecture of the offspring in order to increase bone strength.

Chondrocytes isolated from tibial dyschondroplasia lesions and articular cartilage revert to a growth plate-like phenotype when cultured in vitro

We report here a comparative study of the development and behavior of chondrocytes isolated from normal growth plate tissue, tibial dyschondroplasic lesions, and from articular cartilage. The objective of these studies was to determine whether the properties exhibited by chondrocytes in dysplasic lesions or in articular cartilage were due to their cellular phenotype, their environment, or both. We had previously analyzed the electrolytes and amino acid levels in the extracellular fluid of avian growth plate chondrocytes. Using these data, we constructed a culture medium (DATP5) in which growth plate cells essentially recapitulate their normal behavior in vivo. Here, we used DATP5 to examine the behavior of chondrocytes isolated from lesions of tibial dyschondroplasia (TD). We found that once isolated from lesion and grown in this supportive medium, dysplasic chondrocytes behaved essentially like normal growth plate cells. These findings suggest that the cause of TD is local factors operating in vivo to prevent these cells from developing normally. With respect to articular chondrocytes, our data indicate that they more closely retain normal protein and proteoglycan synthesis when grown in serum-free media. These cells readily induced mineral formation in vitro, both in the presence and absence of serum. However, in serum-containing media, mineralization was significantly enhanced when the cells were exposed to retinoic acid (RA) or osteogenic protein-1 (OP-1). Our studies support previous work indicating the presence of autocrine factors produced by articular chondrocytes in vivo that prevent mineralization and preserve matrix integrity. The lack of inhibitory factors and the presence of supporting factors are likely reasons for the induction of mineralization by articular chondrocytes in vitro.

Bone in the pregnant mother and newborn at birth

BACKGROUND

Changes in maternal bone during pregnancy may affect fetal bone mineralization.

ISSUES

The biphasic changes in maternal bone histology (temporary loss of cancellous bone in early pregnancy restored by term gestation) are consistent with corresponding blood biochemistry changes; increased bone resorption markers in the first trimester, while bone formation markers increased in the last trimester. Postpartum bone mineral density (BMD) by DEXA is increased at cortical bone and decreased at trabecular bone sites compared with prepregnancy values. The mean reduction of spine BMD is 3.5% from prepregnancy to immediate postpartum. Neonatal bone mineral content (BMC) is different by season of birth, low weight relative to gestation, and having a diabetic mother. Lower total body BMC and high bone resorption marker in winter vs. summer-born newborns was related to low vitamin D, indicating alterations of fetal bone metabolism by maternal D deficiency. Lower BMC and decreased bone formation marker in infants born small for gestational age than those born appropriate for gestation may relate to reduced transplacental mineral transfer. Low BMC in infants of diabetic mother was correlated inversely with poor control of maternal diabetes during early pregnancy.

CONCLUSIONS

During pregnancy, maternal bone mineral metabolism are changed, and influences on fetal bone mineralization occur in utero.

Hormones, growth factors and other plasma variables in relation to osteochondrosis

Osteochondrosis (OC) is a multifactorial disorder with endocrinological dysfunction and mineral imbalance having a role in pathogenesis. The present study focused on a possible relationship between insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF-II), parathyroid hormone (PTH), 1,25-dihydroxy-vitamin D (1,25(OH)2D), cortisol, copper, zinc, calcium, ionised calcium, magnesium and phosphorus and 5 different postmortem and radiographical osteochondrosis scores of hock and stifle joints in foals age 0-11 months. Osteochondrosis-positive foals showed a significantly lower IGF-I activity than osteochondrosis-negative foals. PTH, 1,25(OH)2D, cortisol, copper, zinc and calcium also showed significant differences between osteochondrosis-positive and osteochondrosis-negative foals.

Adverse effects of high-calcium diets in humans

While the National Institutes of Health Consensus Conference on Calcium has recommended that all elderly persons need calcium intakes of 1500 mg/day, it also recognizes that adverse effects of high-calcium diets may occur at intakes greater than 2000 mg/day. The purpose of this paper is to highlight adverse effects of high-calcium diets that could have a negative impact on health.

Immunolocalization of osteonectin in avian tibial dyschondroplastic cartilage

Osteonectin is an acidic calcium-binding protein found in cartilage, bone matrix, vascular endothelium, and areas of tissue repair. Using immunocytochemistry, osteonectin has been localized in all zones of the normal avian epiphyseal growth plate with notably high amounts in the hypertrophic zone. In the proximal portion of this zone the staining was intracellular, while in the distal calcifying portion of the hypertrophic zone staining was both intracellular and extracellular. Osteonectin was also detected in the growth plate associated with lesions of chickens with tibial dyschondroplasia (TD). Intense intracellular staining was observed in hypertrophic chondrocytes proximal to the lesion; staining was markedly diminished in the TD lesion; extracellular matrix was devoid of staining. Staining intensity was high along the peripheral edges of the lesion that were undergoing vascularization and resorption. This was the only area in the dysplastic cartilage where staining was observed in the extracellular matrix as well as intracellularly. Similar patterns were viewed in all TD lesions examined, whether they were spontaneous or induced by dietary treatments or genetic selection.

Humeral skeletal development and plasma constituent changes in fetuses of ewes maintained on a low calcium diet from 60 days of gestation

The objective of this study was to evaluate the effects of a long-term, low-calcium diet on fetal calcium metabolism and fetal skeleton development in ewes. Eleven pregnant sheep were assigned to two groups, fed either a diet low in calcium (0.26% total dry matter) or normal in calcium (0.8% total dry matter) for 2 months, starting at 60 days gestational age. The ewes fed the low calcium diet showed lower plasma levels of calcium and higher plasma levels of hydroxyproline, parathyroid hormone, and 1,25(OH)2D compared with the ewes fed the normal calcium diet. There were no differences in these variables between the two groups of fetuses. These observations suggest that the plasma components of calcium homeostasis measured in the fetal lamb in the present study are independent of the ewe and are not significantly affected by the presence of lowered maternal calcium for many weeks during pregnancy. Despite the ability of the fetus of the ewe on the low calcium diet to maintain relatively normal circulating plasma components of calcium homeostasis, long-term maternal hypocalcemia delayed fetal skeletal ossification as shown by histological examination of the fetal humerus. The fetal humerus from low calcium-fed ewes showed a lower proportion of bone versus cartilage (45.6 +/- 5.9 versus 57.4 +/- 4.6%, mean +/- SD) lower ash content (15.4 +/- 1.5 versus 17.4 +/- 1.0%), and lower specific gravity (1.19 +/- 0.2 versus 1.22 +/- 0.02) (P < 0.05) than the humerus from fetuses of normal calcium-fed ewes. This study shows that the long-term calcium intake of the ewe does affect fetal skeletal development, despite a lack of observable effects on fetal plasma concentrations of calcium or known calcium regulating hormones such as 1,25(OH)2D or parathyroid hormone.

The role of nutrition in canine hip dysplasia

The role of nutrition in canine hip dysplasia is a multifactorial as the disease itself. Large and giant breeds primarily are at risk for the disease. Rate of growth, feeding methods, feed consumption, specific nutrients, and electrolyte balances within the diet have all been shown to influence hip dysplasia. Known nutritional risk factors are rapid weight gain and excessive calcium supplementation. Nutritional factors with less secure roles in their influence on the disease process are vitamin C, protein, and carbohydrates. There exists a need to identify further and control the various nutritional factors in the diet that influence canine hip dysplasia.