K.K. Turner

Mineral balance in horses fed two supplemental silicon sources

Numerous studies suggest that silicon (Si) supplementation is beneficial for mineral metabolism and bone health. Mineral balance studies have not been performed in horses to determine how these supplements affect absorption of other minerals. The purpose of these studies was to investigate the effects of two different Si supplements on mineral absorption and retention in horses. Eight geldings were randomly placed in one of two groups: control (CO) or supplemental Si, which was provided by one of two supplements. The first, sodium aluminium silicate (SA), contains a bioavailable form of Si and is high in aluminium (Al). The second supplement contains oligomeric orthosilicic acid (OSA). All horses received textured feed and ad libitum access to hay. Supplemented horses received either 200 g of SA or 28.6 ml of OSA per day. Following a 10-day adaptation period, the horses underwent a 3-day total collection. Blood samples were taken on days 0 and 13. The two balance studies were conducted 4 months apart to reduce carryover effects. Intakes of Al and Si were greater with SA supplementation (p < 0.05). Sodium aluminium silicate increased faecal and urinary Si excretion (p < 0.05). Calcium retention and apparent digestion were increased by SA (p < 0.05). It also maintained plasma Si compared with the CO which tended to have a decrease in plasma Si (p = 0.08). Supplemental OSA increased retention of Ca and B (p < 0.05) and apparent digestion of B (p < 0.01). Orthosilicic acid tended to increase Si retention (p = 0.054), apparent digestion (p < 0.065), and also increased plasma Si. Both supplements were able to alter Ca retention and B metabolism, however, only OSA was able to alter Si retention, digestibility and plasma concentration. Orthosilicic acid, an Si supplement without substantial Al, appears to be a viable option for Si supplementation as it increased Si retention and digestibility.

The effects of ergot alkaloids on the breeding stallion reproductive system

REASONS FOR PERFORMING STUDY Ergot alkaloids cause a range of pathological conditions in mares. There is no evaluation of the effects of ergot alkaloids from endophyte-infected tall fescue on the stallion breeding soundness examination spermiogram. OBJECTIVES The objective of this study was to investigate the effect of ergot alkaloids from endophyte-infected tall fescue on the stallions reproductive functions. STUDY DESIGN Crossover toxicology experiment. METHODS Six stallions were fed either toxic endophyte-infected tall fescue seed or a nontoxic endophyte tall fescue seed (Flecha AR-542, MaxQ). The fescue seed content was compounded at 45% of a grain diet and the stallions were fed the grain diet at 1% of their body weight. The stallions were fed the diet for 70 days, then rested for at least 70 days (no fescue seed) and then fed fescue seed for a second 70 days. At regular intervals blood sampling and a breeding soundness examination were performed. RESULTS The mean time to maximal systemic toxicity was 8.33 h after starting toxic seed ingestion with a mean toxicity level of 49.98 ng alkaloid/mg creatinine. After cessation of feeding toxic seed, the systemic alkaloid concentration fell to control levels within 48 h. There were no significant changes in sperm motility, sperm concentration, sperm cell morphology, total number of sperm cells, number of breeding doses, testicular volume, baseline and human chorionic gonadotropin stimulated testosterone levels. There were no changes in core body temperature and superficial scrotal temperature. The ejaculate from stallions consuming endophyte-infected tall fescue seed had significantly lower gel-free volume (47.5 ± 4.1 ml) than stallions consuming nontoxic endophyte tall fescue seed (62.8 + 4.3 ml, P<0.01). CONCLUSION Ergot alkaloids decreased the gel-free volume of stallions consuming high levels of ergot alkaloids but statistically significant effects on the spermiogram of adult breeding stallions were not found.