Repeated measurements of P retention in ponies fed rations with various Ca:P ratios

Effect of weight change on markers of bone turnover and phosphorus excretion

There is little information about how weight change in horses impacts bone turnover and the metabolism of minerals associated with bone. This study evaluated weight change in mature horses as a factor that could alter bone turnover and fecal P output. Fifteen horses (555±8 kg) were assigned to three treatments: weight loss (LO; n=5), weight maintenance (MA; n=5), and weight gain (GA; n=5). Diets contained 75%, 100%, and 145% of maintenance digestible energy requirements for the three treatments, respectively, but contained similar amounts of protein and minerals. At the end of the weight change period (27±6 d), blood samples were analyzed for bone biomarkers and a 5-day total fecal collection was conducted to measure fecal mineral output. Horses fed the MA diet had an average daily weight change that was not different from either the GA or LO treatments, while weight change was different between the GA group and the LO group (0.49 kg/d vs -1.16 kg/d; P=0.017). Weight change was negatively correlated with cross-linking C-terminal telopeptides of type-I collagen, a biomarker of bone resorption (r=-0.62; P=0.014) and tended to be positively correlated with bone alkaline phosphatase, a biomarker of bone formation (r=0.48; P=0.068). Also, fecal P output tended to be lower in GA than in LO horses (P=0.085), while MA was intermediate and not different, suggesting that weight loss was increasing bone resorption, resulting in a tendency for higher P loss from the body. Weight change in horses can influence bone metabolism as well as mineral excretion.

The Effect of Diet Composition on the Digestibility and Fecal Excretion of Phosphorus in Horses: A Potential Risk of P Leaching?

Simple Summary

This study aimed to examine phosphorus utilization and excretion in feces when typical feeds and forage-based diets are fed. The hypothesis was that feeding regimes might influence phosphorus digestibility and excretion in feces, and therefore the environmental impact of horse husbandry. We also studied the nutrient digestibilities of the diets, as well as the proportion of the soluble fraction of P of the total phosphorus. Horse dung may pose a potential risk of P run-off into the environment if not properly managed. Supplementation with inorganic P should be controlled in the diets of mature horses in light work to decrease the excretion of P in feces.

Abstract

The main horse phosphorus excretion pathway is through the dung. Phosphorus originating from animal dung and manure has harmful environmental effects on waters. The number of horses has increased in many countries, and several studies have pointed that leaching of P from horse paddocks and pastures are hotspots for high P leaching losses. The hypothesis was that feeding regimes might influence phosphorus digestibility and excretion in feces, and therefore the environmental impact of horse husbandry. A digestibility experiment was conducted with six horses fed six forage-based diets to study phosphorus utilization and excretion in feces. The study method was a total collection of feces. The experimental design was arranged as an unbalanced 6 × 4 Latin Squares. Phosphorus intake increased with an increasing concentrate intake. All studied diets resulted in a positive P balance and, the P retention differed from zero in all except the only-hay diet, in which the intake was lower compared to the other diets. The digestibility of P varied from 2.7 to 11.1%, and supplementing forage-diets with concentrates slightly improved P digestibility (p = 0.024), as it also improved the digestibilities of crude protein (p = 0.002) and organic matter (p = 0.077). The horses excreted an average of 20.9 ± 1.4 g/d P in feces. Excretion was smallest (20.0 g) in horses on a hay-only diet (p = 0.021). The average daily phosphorus excretion resulted in 7.6 kg P per year. The soluble P part of the total P in feces accounted for about 88% of the P excreted in feces, and is vulnerable to runoff losses and may leach into waters. Thus, horse dung may pose a potential risk of P leaching into the environment if not properly managed, and is not less harmful to the environment than that from other farm animals. Supplementation with inorganic P should be controlled in the diets of mature horses in light work to decrease the excretion of P in feces.

Multi-generational drinking of bottled low mineral water impairs bone quality in female rats

BACKGROUND

Because of reproductions and hormone changes, females are more sensitive to bone mineral loss during their lifetime. Bottled water has become more popular in recent years, and a large number of products are low mineral water. However, research on the effects of drinking bottled low mineral water on bone health is sparse.

OBJECTIVE

To elucidate the skeletal effects of multi-generational bottled water drinking in female rats.

METHODS

Rats continuously drank tap water (TW), bottled natural water (bNW), bottled mineralized water (bMW), or bottled purified water (bPW) for three generations.

RESULTS

The maximum deflection, elastic deflection, and ultimate strain of the femoral diaphysis in the bNW, bMW, and bPW groups and the fracture strain in the bNW and bMW groups were significantly decreased. The tibiae calcium levels in both the bNW and bPW groups were significantly lower than that in the TW group. The tibiae and teeth magnesium levels in both the bNW and bPW groups were significantly lower than those in the TW group. The collagen turnover markers PICP (in both bNW and bPW groups) were significantly lower than that in the TW group. In all three low mineral water groups, the 1,25-dihydroxy-vitamin D levels were significantly lower than those in the TW group.

CONCLUSION

Long-term drinking of low mineral water may disturb bone metabolism and biochemical properties and therefore weaken biomechanical bone properties in females. Drinking tap water, which contains adequate minerals, was found to be better for bone health. To our knowledge, this is the first report on drinking bottled low mineral water and female bone quality on three generation model.