Preservation Method of Rumen Fluid Collected From Harvested Cattle Alters in vitro Digestibility of Reference Feedstuffs

The objective of our experiment was to evaluate preservation and revitalization strategies for rumen inoculum anticipating research and veterinary applications. Rumen fluid samples were collected from 12 harvested cattle. Liquid samples were divided into five 500-mL aliquots which were randomly allocated to one of five treatments in a 2 × 2 + 1 augmented factorial design. Factors included preservation method [freezing (FZN) or lyophilization (LYO)] and preservative (glycerol; + or –). A fresh control (CON) was maintained from each sample. Feedstuffs used in this experiment were alfalfa hay, Coastal bermudagrass hay, cracked maize, rice bran, and soybean meal. Reference feedstuffs were subjected to batch culture in vitro true digestibility (IVTD) and in vitro NDF digestibility (IVNDFD) assays using inoculum from each of the five treatments. There was an effect (P < 0.05) of preservation method, preservative, and their interaction for both IVTD and IVNDFD of each of the five references feedstuffs. Freezing or lyophilization of rumen inoculum reduced (P < 0.05) IVTD and IVNDFD of reference feeds relative to the CON. Despite lower degradation of feeds when frozen or lyophilized rumen fluid was used rather than fresh, differences between them in IVTD and IVNDFD suggest that, in the absence of fresh inoculum, preserved rumen fluid may be a viable option for veterinary applications, such as transfaunation, but likely will not be viable for research applications.

Effects of crude protein content on intake and digestion of coastal bermudagrass hay by horses

This study was conducted to determine the effects of forage CP level on intake and digestion of Coastal bermudagrass hay by horses. Four cecally fistulated geldings were used in a 4 × 4 Latin square design with four treatments and four periods. Horses were fed one of four Coastal bermudagrass hays consisting of 7, 10, 13, or 16% CP during each of the four 15-d periods. Intake and apparent digestibility were determined for each horse at the end of each period by total fecal collection. In addition, cecal fluid and blood samples were collected on the last day of each period for determination of cecal ammonia, cecal pH, plasma urea nitrogen, and plasma glucose concentrations. Data were analyzed using PROC MIXED of SAS. Crude protein concentration of Coastal bermudagrass hay influenced equine intake and digestion. Increasing CP concentration linearly increased digestible OM intake (DOMI) from 3.79 to 5.98 kg/d for 7 and 16% CP hay, respectively (P = 0.04). Furthermore, as forage CP level increased, CP intake increased linearly (P < 0.01). Forage CP level had no effect on forage DM intake. Quadratic effects (P ≤ 0.05) were observed for forage OM, NDF, ADF, and digestible energy. Overall digestibility was lowest for the 7% CP hay and highest for the 10% CP hay. Cecal pH remained above 6.62 irrespective of treatment and time, indicating that cecal pH was suitable for microbial growth. As forage CP level increased, cecal ammonia concentration increased linearly from 0.03 mM for the 7% to 1.74 mM for the 16% CP hay (P < 0.01). Concentration of plasma glucose also linearly increased (P = 0.04) from 68.77 to 73.68 mg/dL as CP concentration increased from 7% to 16% CP. Plasma urea nitrogen exhibited a quadratic effect as concentration increased (P < 0.01) from 4.34 to 5.61 mM for the 7 and 16% CP hays, respectively. Overall, the 10% CP hay had the highest digestibility due to its higher OM digestion. As forage OMI increased, digestible OM increased until physiological capacity for digestion is exceeded. At that point, digestion will decline with the decrease in OMI, explaining the lower digestion for other forages fed.

112 Effect of an Oral Joint Supplement on Gait Kinematics and Biomarkers of Cartilage Metabolism and Inflammation in Mature Riding Horses

Twenty stock-type horses (589 ± 126 kg BW; 13 ± 8 yr) were utilized in a completely randomized design for a 28-d trial to evaluate a joint supplement on gait kinematics, inflammation and cartilage metabolism. Horses were stratified by age, sex, body weight (BW), and initial lameness score and were randomly assigned to 1 of 2 dietary treatments consisting of either a 100 g placebo top-dressed daily to 0.6% BW (as-fed) commercial concentrate (CON; n = 10), or an oral joint supplement (SmartPak Equine LLC) containing glucosamine, chondroitin sulfate, hyaluronic acid, methylsulfonylmethane, turmeric, resveratrol, collagen, silica, and boron (TRT; n = 10). Horses had ad libitum access to coastal bermudagrass hay (Cynodon dactylon) and exercised progressively 4 d/wk, for 45 min/d. On d 13 and 27, blood was harvested following a 19.3 km exercise stressor. Every 14 d, blood was collected for plasma prostaglandin E2 (PGE2), and serum collagenase cleavage neopeptide (C2C), carboxypropeptide of type II collagen (CPII), and chondroitin sulfate 846 epitope (CS846). Gait kinematics were analyzed every 14 d (Kinovea v.0.8.15) to determine stride length (SL) and range of motion (ROM) of the knee and hock at the walk and trot. Data were analyzed using PROC MIXED of SAS. Hock ROM increased in TRT (P ≤ 0.02) at the walk and tended to increase at the trot (P = 0.09). At the walk, SL and knee ROM increased (P ≤ 0.01) in all horses. C2C and CPII increased over time (P ≤ 0.05) and no effect was observed for CS846 or PGE2 (P > 0.12). In response to the exercise stressor, CPII and PGE2 decreased (P ≤ 0.05) from d 13 to 14, and CS846 and PGE2 tended to decrease (P ≤ 0.10) from d 27 to 28, independent of diet. In conclusion, hock ROM at the walk and trot was the most sensitive to TRT, but biomarker concentration of collagen metabolites and systemic inflammation was not altered in 28 d.

Evaluation of an oral joint supplement on gait kinematics and biomarkers of cartilage metabolism and inflammation in mature riding horses

Twenty stock-type horses (589 ± 126 kg BW; 13 ± 8 yr) were used in a completely randomized design for 28-d to evaluate the impact of a joint supplement on gait kinematics, inflammation, and cartilage metabolism. Horses were stratified by age, sex, body weight (BW), and initial lameness scores and were randomly assigned to one of two dietary treatments consisting of either a 100-g placebo top-dressed daily to 0.6% BW (as-fed) commercial concentrate (CON; n = 10; SafeChoice Original, Cargill, Inc.), or an oral joint supplement (SmartPak Equine LLC) containing glucosamine, chondroitin sulfate, hyaluronic acid, methylsulfonylmethane, turmeric, resveratrol, collagen, silica, and boron (TRT; n = 10). Horses were group-housed with ad libitum access to coastal bermudagrass hay (Cynodon dactylon) and allowed to graze pasture 2 h/d. Horses were exercised progressively 4 d/wk at 45 min each. On days 13 and 27, blood was harvested followed by a 19.3-km exercise stressor on concrete. Horses traveled at the walk, with no more than 15 min at the trot. Every 14 d, BW and BCS were recorded, and blood was collected for plasma prostaglandin E2 (PGE2), serum collagenase cleavage neopeptide (C2C), carboxypropeptide of type II collagen (CPII), and chondroitin sulfate 846 epitope (CS846) analysis. Kinematic gait analysis was performed every 14 d (Kinovea v.0.8.15) to determine stride length (SL) and range of motion (ROM) of the knee and hock at the walk and trot. Data were analyzed using PROC MIXED of SAS. All horses increased BW and BCS over time (P ≤ 0.01). Hock ROM increased in TRT horses (P ≤ 0.02) at the walk and tended to increase at the trot compared to CON (P = 0.09). At the walk, SL and knee ROM increased over time, independent of dietary treatment (P ≤ 0.01); no time effect was observed at the trot (P > 0.15). Regardless of treatment, C2C and CPII increased over time (P ≤ 0.05) and no effect was observed for CS846 or PGE2 (P > 0.12). In response to the exercise stressor, CPII and PGE2 decreased (P ≤ 0.05) from day 13 to 14, and CS846 and PGE2 tended to decrease (P ≤ 0.10) from day 27 to 28, independent of dietary treatment. In conclusion, hock ROM at the walk and trot was most sensitive to dietary treatment. Supplementation did not alter biomarker concentration of collagen metabolites or systemic inflammation in the 28-d period, but a future study utilizing arthrocentesis may be warranted to specifically evaluate intra-articular response to dietary treatment.

Evaluation of dietary trace mineral supplementation in young horses challenged with intra-articular lipopolysaccharide1

Sixteen weanling Quarter Horses (255 ± 22 kg) were utilized in a 56-d trial to evaluate the effects of trace mineral (TM) source on intra-articular inflammation following a single acute inflammatory insult. Horses were stratified by age, sex, and BW and then randomly assigned to dietary treatment: concentrate formulated with Zn, Mn, Cu, and Co as inorganic sources (CON; n = 8) or complexed TMs (CTM; n = 8). Added TM were formulated at iso-levels across treatments and intakes met or exceeded NRC requirements. Horses were offered 1.75% BW (as-fed) of treatment concentrate and 0.75% BW (as-fed) coastal Bermudagrass hay. Growth measurements were collected on days 0, 28, and 56, and plasma was collected biweekly for determination of Mn, Cu, Zn, and Co concentrations. On day 42, carpal joints were randomly assigned to receive injections of 0.5 ng lipopolysaccharide (LPS) or sterile lactated Ringer’s solution (LRS; contralateral control). Synovial fluid was collected at preinjection hours (PIH) 0, and 6, 12, 24, 168, and 336 h post-injection and analyzed for TM concentration, prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), collagenase cleavage neopeptide (C2C), and aggrecan chondroitin sulfate 846 epitope (CS846). Data were analyzed using the MIXED procedure of SAS. Results showed a TM source × LPS × h effect for synovial fluid Co, Cu, and Se (P < 0.05); concentrations of TM peaked at hour 6 and decreased to preinjection values by hour 168 in both CON and CTM–LPS knees. A delayed peak was observed at hour 12 for CTM–LRS. Peak synovial fluid Cu and Se concentrations were higher in LPS knees, and Co was highest in CTM–LPS. A TM source × h interaction was observed for Zn (P < 0.05); concentrations peaked at hour 6 in CON vs. hour 12 for CTM. An LPS × h interaction was observed for Mn (P < 0.01); synovial concentration peaked at hour 6 in LPS knees compared with hour 24 in LRS. Synovial PGE2, C2C, CPII, and CS846 concentrations were greater with LPS (P ≤ 0.01), and C2C was greater (P < 0.01) in CTM compared with CON. Concentrations of CPII and PGE2 were unaffected by diet. A TM source × h × LPS interaction was observed for CS846 (P = 0.02). Concentrations of CS846 in CTM peaked at 12 h, whereas CON peaked at a lower concentration at 24 h (P < 0.05). Data indicate sufficient intake of a complexed TM source may support cartilage metabolism through increased aggrecan synthesis and type II collagen breakdown following an intra-articular LPS challenge in growing horses.

Digestibility and Retention Time of Coastal Bermudagrass (Cynodon dactylon) Hay by Horses

Bermudagrass (Cynodon dactylon) and other warm-season grasses are known for their increased fiber concentrations and reduced digestibility relative to cool-season grasses and legumes. This study investigated the digestive characteristics and passage kinetics of three maturities of Coastal bermudagrass hay. A 5 × 5 Latin square design experiment was used to compare the digestion of five hays: alfalfa (Medicago sativa, ALF), orchardgrass (Dactylis glomerata, ORCH), and Coastal bermudagrass harvested at 4 (CB 4), 6 (CB 6), and 8 weeks of regrowth (CB 8). Horses were fed cobalt-ethylenediaminetetraacetic acid (Co-EDTA) and ytterbium (Yb) labeled neutral detergent fiber (NDF) before an 84-h total fecal collection to determine digesta retention time. Dry matter digestibility was greatest for ALF (62.1%) and least for CB 6 (36.0%) and CB 8 diets (36.8%, SEM = 2.1; p < 0.05). Mean retention time was longer (p < 0.05) for Coastal bermudagrass (particulate 31.3 h, liquid 25.3 h) compared with ORCH and ALF (28.0 h, SEM = 0.88 h; 20.7 h, SEM = 0.70 h). Further evaluation of digesta passage kinetics through mathematical modeling indicated ALF had distinct parameters compared to the other diets. Differences in digestive variables between forage types are likely a consequence of fiber physiochemical properties, warranting further investigation on forage fiber and digestive health.

PSVII-41 Mare colostrum and milk composition through 36 h post-parturition

Sixteen Quarter Horse mares (mean±SEM; 12±5 yr; 5.1±1.0 BCS; 579±9 kg BW) were used to evaluate the time course of the nutrient profile of colostrum and milk following parturition. Mares received a commercial concentrate designed to meet NRC (2007) requirements for gestating mares and were fed to maintain a BCS between 5 and 7. Horses were group housed in dry lots with ad libitium access to coastal Bermudagrass hay and water. As soon as parturition was observed, colostrum was collected by hand pre-suckle (0 h post-parturition), and at 6, 12, 24, and 36 h post-parturition. Samples were evaluated for concentrations of protein, fat, lactose, somatic cell count (SCC), urea nitrogen, and non-fat solids (NFS) by a commercial laboratory. Differences between means were determined using PROC MIXED in SAS (v9.4) with time as a repeated measure. Following parturition, colostrum protein and NFS decreased from h 0 to 6 (protein: 13.1±0.7 to 9.7±0.8%; NFS: 20.9±0.8 to 16.8±0.9%) and from h 6 to 12 (P0.04). Protein continued to show a trend for a decrease from h 12 to 24 (P = 0.08), plateauing around 3%. NFS remained around 10% from h 12 to 36. Conversely, lactose did not change from h 0 to 6 (3.6±0.2 to 3.9±0.2%) but increased from 6 to 12 h (5.5±0.2%) post-parturition (P &lt; 0.0001). Fat, SCC, and urea nitrogen remained unchanged through 36 h post-parturition. These results indicate colostrum protein concentration decreases as early as 6 h post-parturition, and the non-fat solid portion of milk shifts from primarily proteins to lactose. However, the impact of these changes on foal health should be more clearly defined.

PSVII-40 Influence of mare body fat measures on colostrum composition

Sixteen Quarter Horses (mean±SEM; 12±5 yr; 5.1±1.0 BCS; 579±9 kg BW) were used to test the hypothesis that mare body fat was related to colostrum composition. Mares received a commercial concentrate to meet NRC (2007) requirements and to maintain a BCS between 5 and 7. Horses were group-housed in dry lots with ad libitium access to coastal Bermudagrass hay. Within 1 wk of expected foaling date, ultrasound images were obtained to determine rump fat, intramuscular fat (IMF), and longissimus dorsi area and fat thickness (LDF) at the 13th/14th and 17th/18th ribs. At parturition, colostrum was collected by hand and evaluated for Brix%, immunoglobulin (Ig) concentrations by commercial ELISA, and concentrations of protein, fat, lactose, somatic cell count, urea nitrogen, and non-fat solids (NFS) by a commercial laboratory. Correlations were determined using PROC CORR in SAS (v9.4). Significant correlations are presented in Table 1. Overall, mare LDF was correlated with protein, lactose, and NFS but was not related to Ig concentrations. Further, the common on-farm test for colostrum quality (Brix%) positively correlated with Ig, protein, and NFS levels.