Effect of longeing and glucosamine supplementation on serum markers of bone and joint metabolism in yearling quarter horses.

The effect of longeing and glucosamine supplementation on known biological markers of joint disease was studied in yearling quarter horses. Twenty-one yearling quarter horses were randomly assigned to one of 4 treatments: 1) longeing (longeing 20 min daily) supplement control (LN); 2) longeing/glucosamine (LG); 3) walking (mechanical walker for 120 min daily (WN)); and 4) walking/glucosamine (WG). Oral glucosamine was administered at 5.5 g b.i.d. weeks 1-4, 3.5 g b.i.d. during weeks 5-6, and 2.0 g b.i.d. during weeks 7-8. Serum was obtained weekly for 8 wk and analyzed for keratan sulfate and osteocalcin concentrations. Walked horses receiving glucosamine showed slight elevation in serum keratan sulfate compared to controls (P = 0.04). Glucosamine or longeing exercise had no significant effect (6 > or = 0.08) on serum osteocalcin concentrations. Under these conditions, longeing and/or glucosamine supplementation did not significantly alter serum concentrations of keratan sulfate or osteocalcin.

Assessing the fertility potential of equine semen samples using the reducible dyes methylene green and resazurin.

The objective of this study was to determine if spermatozoal reduction of the dyes methylene green to colorless and resazurin to pink or colorless was associated with the fertility potential of an equine semen sample. Fifty samples from 38 stallions were evaluated for the number of spermatozoa per milliliter and number of motile sperm per milliliter. Methylene green (20 micrograms/mL of semen) or resazurin (85 micrograms/mL of semen) was added to 3-mL aliquots of semen. Semen samples were identified as having low fertility potential (< 200 x 10(6) total cells/mL and < 140 x 10(6) motile cells/mL) or high fertility potential (> or = 200 x 10(6) total cells/mL and > or = 140 x 10(6) motile cells/mL). The sensitivities were 80% for the methylene green, 68% for the resazurin to pink, and 60% for the resazurin to colorless tests. The specificities were 80% for the methylene green, 79% for the resazurin to pink, and 92% for the resazurin to colorless tests. The overall accuracies were 80% for the methylene green test, 74% for the resazurin to pink test, and 76% for the resazurin to colorless tests. The methylene green and resazurin reduction tests can provide valuable information on the fertility potential of an equine semen sample.