Search

The objective of this study was to determine if in vitro methodologies developed for the Ankom [Daisy.sup.II] incubator could produce accurate estimates of in vivo equine DM digestibility (DMD) and NDF digestibility (NDFD) when equine feces were used as the inoculum source. Four mature geldings were utilized in a 4 x 4 Latin square design experiment with a 2 x 2 factorial arrangement of dietary treatments (timothy hay, alfalfa hay, timothy hay plus oats, and alfalfa hay plus oats), in which the geldings were individually housed and fed. During each 5-d total fecal collection period, feces were collected and composited daily and used to calculate in vivo digestibility. Digestion of the 4 treatment diets was evaluated in vitro using the [Daisy.sup.II] incubator. Each incubation vessel of the [Daisy.sup.II] was assigned to 1 of the horses and contained 18 filter bags (6 containing the assigned treatment hay, 6 containing hay-oat mix, and 6 containing oats). Three incubation periods were evaluated: 30, 48, and 72 h. Although the 30- and 48-h in vitro estimates were consistently less than the in vivo estimates, they ranked diets in the same order as the in vivo method. For the alfalfa oat diet, timothy diet, and the timothy oat diet, the mean 72-h in vitro DMD and in vivo DMD were not different (P = 0.1444). However, for the alfalfa diet, the DMD estimate from 72-h in vitro incubation was less than the in vivo estimate (P < 0.010). For NDFD, the timothy diet was the only diet, in which the mean 72-h in vitro NDFD estimate was not different than the in vivo estimate. However, the in vitro method correctly ranked the alfalfa-based diets as having greater NDFD estimates than the timothy-based diets. Of the 3 incubation periods, the 72-h period provided digestibility estimates most similar to the in vivo data. Using the methodologies described in this research, the [Daisy.sup.II] incubator and equine feces can be used to estimate in vivo DMD of horse feeds. Key words: [Daisy.sup.II] incubator, digestibility, feces, horse, in vitro, in vivo doi: 10.2527/jas.2010-2989

Thirteen horses of Thoroughbred or Standardbred breeding were used to study the effect of dietary fish oil supplementation on blood lipid characteristics. Horses were assigned to either fish oil (n = 7) or corn oil (n = 6) treatment groups for 63 d. The fish oil contained 10.8% eicosapentaenoic acid (EPA) and 8% docosahexaenoic acid (DHA). Each horse received timothy hay and a mixed-grain concentrate at rates necessary to maintain BW. Oil (corn or fish) was top-dressed on the concentrate daily at a rate of 324 mg/ kg of BW. The n-6:n-3 ratio was approximately 3.6:1 for horses receiving the corn oil diet and 1.4:1 for horses receiving the fish oil diet. Horses were exercised 5 d/ wk during the study. Before supplementation, there was no difference in the concentrations of any serum fatty acids between the 2 treatment groups. The mean basal concentrations of EPA and DHA on d 0 were 0.04 and 0.01 mg/mL, respectively. After 63 d, horses receiving the fish oil treatment, but not those receiving the corn oil treatment, had increased concentrations of EPA and DHA (P < 0.05). Fish oil supplementation for 63 d also increased the concentrations of C22:0, C22:1, and C22:5 fatty acids (P < 0.05). Overall, horses receiving fish oil had a decreased concentration of n-6 fatty acids (P < 0.05) and a greater concentration of n-3 fatty acids (P < 0.01), resulting in a lower n-6:n-3 fatty acid ratio after 63 d (P < 0.05). Serum cholesterol concentrations increased (P < 0.05) during the supplementation period in horses receiving the corn oil but not in horses receiving the fish oil. Compared with horses receiving corn oil, horses receiving fish oil had lower serum triglycerides at d 63 (P < 0.05). These results demonstrate that 63 d of fish oil supplementation at 324 mg/kg of BW was sufficient to alter the fatty acid profile and blood lipid properties of horses receiving regular exercise. Key words: exercise, omega-3 fatty acid, fish oil, horse

Ten horses of Thoroughbred or Standardbred breeding were used to study the effects of dietary fish oil supplementation on the metabolic response to a high-intensity incremental exercise test. Horses were assigned to either a fish oil (n = 6) or corn oil (n = 4) treatment. The fish oil (Omega Protein, Hammond, LA) contained 10.6% eicosapentaenoic acid and 8% docosahexaenoic acid. Each horse received timothy hay and a textured concentrate at a rate necessary to meet its energy needs. The supplemental oil was top-dressed on the concentrate daily at a rate of 324 mg/ kg BW. Horses received their assigned diet for 63 d, during which time they were exercised 5 d/wk in a round pen or on a treadmill. During wk 1, horses exercised for 10 min at a trot. After wk 1, exercise time and intensity were increased so that at wk 5, exercise time in the round pen increased to 30 min (10 min of cantering and 20 min of trotting) per day. Starting at wk 6, horses were exercised 3 d/wk in the round pen for 30 min and 2 d/wk on a treadmill for 20 min. After 63 d, all horses performed an exercise test consisting of a 5-min warm-up at 1.9 m/s, 0% grade, followed by a step test on a 10% grade at incremental speeds of 2 to 8 m/s. Blood samples were taken throughout exercise. During exercise, horses receiving fish oil had a lower heart rate (treatment x time interaction; P < 0.05) and tended to have lower packed cell volume (treatment effect; P = 0.087). Plasma lactate concentrations were not affected by treatment. Plasma glucose concentrations were not different between groups during exercise but were lower (treatment z time interaction; P < 0.01) for the fish oil group during recovery. Serum insulin tended to be lower in fish oil horses throughout exercise (treatment effect; P = 0.064). There was a tendency for glucose: insulin ratios to be higher for fish oil-treated horses throughout exercise (treatment effect; P = 0.065). Plasma FFA were lower (treatment x time interaction; P < 0.01) in horses receiving fish oil than in horses receiving corn oil during the initial stages of the exercise test. Serum glycerol concentrations also were lower in fish oil-treated horses (P < 0.05). Serum cholesterol concentrations were lower in horses receiving fish oil (treatment effect; P < 0.05), but serum triglycerides were not affected by treatment (P = 0.55). These data suggest that addition offish oil to the diet alters exercise metabolism in conditioned horses. Key Words: Dietary Fat, Equine, Exercise, Fish Oil, Horse, Omega-3 Fatty Acids

Because exercise fatigue has been associated with the accumulation of lactic acid, factors that influence lactate metabolism during exercise can potentially enhance performance. The objective of this study was to examine the effects of supplemental betaine on eight mature Thoroughbred horses before and after 8 wk of conditioning. The effects of betaine were tested in two cross-over design experiments, allowing each horse to receive both the control and betaine treatments at each fitness level. Ingestion of 80 mg of betaine/kg of BW for 14 d before exercise testing did not alter plasma lactate, glucose, free fatty acids (FFA), or triglyceride concentrations during exercise in the untrained or trained horses. A time x treatment interaction (P < .05) was observed for plasma lactate in untrained horses during recovery from exercise, and plasma lactate concentrations were lower (P < .05) at 60 min after exercise when untrained horses received betaine. Plasma FFA concentrations were lower (P < .05) before exercise and at 720 min after exercise when untrained horses received betaine. These data indicate that betaine may influence lactate metabolism following exercise in untrained horses; however, betaine does not seem beneficial for trained horses. Key Words: Horses, Exercise, Betaine, Lactic Acid

The effect of vitamin E intake on indicators of muscle integrity was studied in exercised horses. Nineteen horses were blocked by sex and then assigned to one of three diets: no supplemental vitamin E (BASAL), BASAL plus 80 IU of supplemental vitamin E/kg DM (80), or BASAL plus 300 IU of supplemental vitamin E/kg DM (300). The BASAL diet contained less than 44 IU of vitamin E/kg DM, but it was adequate in all other nutrients. During the 90-d treatment period, horses were exercised 5 d/wk; in addition, serum and middle gluteal muscle [Alpha]-tocopherol concentrations were measured at 0, 30, and 90 d. All horses performed a repeated submaximal exercise test (RSET) at the end of the 90-d period. The following were measured before and after the RSET: [Alpha]-tocopherol, thiobarbituric acid reactive substances (TBARS), conjugated diene (CD) concentrations of the middle gluteal muscle, and serum creatine kinase (CK) and aspartate aminotransferase (AST) activities. Serum [Alpha]-tocopherol concentrations of horses receiving the BASAL and 80 diets decreased (P < .05 and P < .06, respectively) during the 90-d treatment period but did not change in horses receiving the 300 diet. Serum and muscle [Alpha]-tocopherol concentrations were higher (P < .05) at 30 and 90 d in horses receiving the 300 diet than in horses receiving the BASAL and 80 diets. Serum CK and AST activities increased (P < .05) following RSET but were not affected by dietary vitamin E level. Muscle [Alpha]-tocopherol level did not affect muscle CD or TBARS. Key Words: Horses, Vitamin E, Creatine Kinase, Muscles

A new procedure to type Listeria monocytogenes involving random amplification of polymorphic DNA (RARD) profiles derived from 10-mer oligonucleotide OPM-01 was developed. It produced simpler and more accurate patterns than previously accomplished and also facilitated the differentiation of serotype 46 strains. OPM-01 was also tested for use in RAPD analysis of 91 strains of L. monocytogenes. The profiles derived contained 1 to 10 bands ranging in molecular sizes of 0.5 to 5.0 kbp.