D.R. Linden’s research while affiliated with The Ohio State University and other places

Group turnout provides important socializing opportunities for horses, particularly those that are primarily stalled. A high percentage of equine injuries occur during group turnout, which could partly be due to the physical constraints of fencing. In order to investigate appropriate paddock sizes for group turnouts, horses (n=12) from a single herd were divided into groups of 4, stalled for 24 hours, and then turned out for 1 h into one of three differently sized pens: 342, 263, and 184 m² per horse. Groups rotated through pens across three days, receiving one treatment per day. Blood was sampled for cortisol concentrations at 0800 h each morning, and then at 15 and 60 min into the turn out sessions, and 60 min following return to individual stalls. Groups rotated through three turnout times: 0900, 1200, 1400 h. Counts of agonistic behaviors (chasing, contact biting and kicking) and low-level threats (pinned ears, tail swishing, bite and kick threats) were recorded. When turned out in pens that provided 342 m² per horse, horses exhibited reduced plasma cortisol concentrations by 15 minutes post turnout and at 1 h following return to their stalls (P < 0.05). Horses in pens providing 184 m² per horse exhibited greater agonistic (P < 0.001) and low-level threat (P < 0.01) behaviors than horses in larger pens. These data provide insight into appropriate pen sizes for horses from established herds. Providing at least 342 m² per horse may reduce the chance of injury in horses accustomed to group turnout.

When fed to horses, high-starch diets elevate plasma concentrations of interleukin-1β (IL-1β) as soon as 1 hour posteating. This increase in IL-β is possibly because of changes in intestinal pH that result from rapid bacterial fermentation of starches and sugars in the digestive tract. The purpose of this research was to investigate the effect of feeding 0.9 kg of grass hay 30 minutes before feeding a concentrate meal on the postprandial rise in IL-1β, compared with control horses receiving the same concentrate without hay first. Six mature geldings were used in a switchback design. Horses were fasted overnight before being offered a concentrate feed that provided 1.2 g/kg bodyweight of nonstructural carbohydrates. Plasma was harvested 30 minutes before hay feeding and 1, 2, 4, 6, and 8 hours postfeeding. Concentrations of IL-1β and d-lactate were analyzed by repeated measures analysis of variance. The hay-first treatment reduced (P = .034) postprandial concentrations of IL-1β at all time points compared with the control horses. An interaction between hour and treatment was detected for mean d-lactate concentrations (P = .037), with lower concentrations in hay-first fed horses at postfeeding hours 1, 2, and 4, compared with control horses. Given these findings, we believe that feeding a small amount of hay before feeding a meal of moderate starch and sugar content reduced the negative effects of rapid starch and sugar fermentation in the equine digestive tract, evidenced by reduced postprandial d-lactate and IL-1β concentrations.

Animal Nutrition (AN) is a 3000-level course with a sole prerequisite of Introductory Animal Science. The 2012 quarter to semester conversion process resulted in fewer opportunities for students to complete chemistry prior to enrolling in AN, particularly if those students required remedial math courses. Anecdotal observations of the instructors suggested that students seemed less prepared for AN than in years when chemistry was a required prerequisite. In order to accommodate this, lecture content was restructured to reduce the reliance on chemistry knowledge. This was completed through removing three lectures (carbohydrate, protein, and lipid chemistry), and shortening lectures on digestion and metabolism to remove chemistry details. The objective of this research was to examine final course grades in AN over 7 semesters of offering (n=275 students), in order to determine the effect of prior enrollment in chemistry and altered course structure on final grades. Students that previously completed chemistry (n=53) had higher (P < 0.001) final grades (80 ± 1.7%) compared to those that did not (71.8 ± 1.0%). This finding is possibly due to students being better prepared for AN through exposure to chemistry concepts. However, it is also possible that students who were able to take chemistry prior to AN did not require remedial coursework, and were naturally stronger students. Students that took AN after it was restructured (n=67 students) had a tendency (P = 0.06) for lower grades (74 ± 1.6%) than those completing the course prior to restructuring (78 ± 1.1%). These results support the notion that exposure to chemistry concepts enables animal science students to more fully understand the content taught in AN. Requiring chemistry as a prerequisite will likely improve the chances of success for students completing a course in AN. Key Words:

When fed to horses, high starch diets elevate plasma concentrations of IL-1β as soon as 1 hour post eating. This increase in IL-β is possibly due to changes in intestinal pH that result from rapid bacterial fermentation of starches and sugars in the digestive tract. This altered pH may disrupt the gut microbial environment and ultimately lead to inflammation. The purpose of this research was to investigate the effect of feeding 0.9 kg of grass hay 30 minutes prior to feeding a concentrate meal (HF) on the postprandial rise in IL-1β, as compared to control horses receiving the same concentrate without hay first (HS). Six mature light-breed geldings of moderate body condition (5-6 on a scale of 1-9) were used in a switchback design. Horses were fasted overnight prior to being offered a concentrate feed at 0800 hours that provided 1.2 g/kg bodyweight of nonstructural carbohydrates. Plasma from blood was harvested at -30 minutes (sample obtained prior to hay feeding), 1, 2, 4, 6, and 8 hours post feeding. Horses were offered ad libitum grass hay following completion of their concentrate meal. Concentrations of IL-1β, d-lactate, glucose, and insulin were analyzed by repeated measures ANOVA (SAS v. 9.3). Where necessary, values were log transformed and are presented as geometric means. The HF treatment reduced postprandial geometric mean concentrations of IL-1β compared to the HS treated horses at post-feeding hours 2 (296 [263-330] vs. 449 [402-500] pg/mL, p=0.010), 4 (272 [244-303] vs. 474 [425-530] pg/mL, p<0.001), and 6 (257 [230-287] vs. 439 [ 394-490] pg/mL, p=0.001). The HF treatment also decreased mean d-lactate concentrations at post-feeding hours 2 (1188 ± 110 vs. 1509 ± 110 μmol/L, p=0.049) and 4 (1186 ± 110 vs. 1581 ± 110 μmol/L, p=0.018), as compared to HS treated horses. Plasma glucose and insulin increased postprandially for both treatments (p < 0.001) with no effect of HF treatment (p > 0.5). Given these findings, we believe that feeding a small amount of hay prior to feeding a meal of moderate starch and sugar content, reduced the negative effects of rapid starch and sugar fermentation in the equine digestive tract, as seen through reduced postprandial d-lactate and IL-1β concentrations.