Kari K. Turner

When measuring real-time in vivo muscle fatigue with electromyography (EMG), data collection can be compromised by premature sensor removal or environmental noise; therefore, the objective of this study was to develop a postmortem in vivo methodology to induce muscle fatigue and measure it using EMG. Barrows (N = 20) were stratified by weight and randomly allocated into one of two treatments. The treatments consisted of barrows being subjected to a hog electric stunner super-contraction cycle (ES) or not (CON) postmortem. The right hind limb bicep femoris (BF) and semitendinosus (ST) were selected for ambulatory movement simulation using electronic muscle stimulation (EMS). Muscle workload during EMS was measured with EMG using median power frequency (MdPF) and root mean square (RMS) as indicators of action potential velocity and muscle fiber recruitment. Ambulatory movement was induced and recorded for 20 min with a 4:4 duty cycle at 70 Hz. Muscle biopsies were collected pre- and post-EMS for metabolite analyses to corroborate muscle fatigue onset. There was a TRT × Muscle interaction for normalized RMS percentage (p < 0.01), where BF from CON barrows had greater values (p < 0.01). There were no interactions or TRT main effects for the MdPF normalized value (p ≥ 0.25), but there were Period and muscle effects on MdPF (p < 0.01). Bicep femoris had smaller (p < 0.01) MdPF than ST. The percentage of MdPF decreased (p < 0.01) by Period 5 compared to the other Periods, which did not differ from each other (p ≥ 0.38). There were TRT × Muscle and Muscle × Period interactions for ATP muscle concentration (p ≤ 0.03). The concentration of CON BF ATP was greater (p < 0.01) than that of ES BF and CON and ES ST, which did not differ from each other (p ≥ 0.11), but the APT concentration tended to differ between ES BF and ES ST (p = 0.06). Semitendinosus ATP concentration decreased (p < 0.01) post-EMS compared to ST pre- and BF pre- and post-EMS (p ≥ 0.29), but BF and ST concentration tended to differ pre-EMS (p = 0.07). The data indicated that EMS is a valuable tool for replicating ambulatory movement or physical activity, but super-contraction is not a means to accelerate postmortem muscle fatigue onset. Therefore, further refinement, such as longer EMS stimulation time, should be considered.

The objective of this study was to determine the daily dietary nicotinamide riboside (NR) dose required to maximize the delay of subjective muscle fatigue onset. Barrows (N = 100) were assigned to one of five treatments: a conventional swine finishing diet containing 0 (CON), 15 (15NR), 30 (30NR), 45 (45NR) mg·kg body weight⁻¹·d⁻¹ NR, or CON supplemented with 45 mg·kg body weight⁻¹·d⁻¹ NR by drench or cookie dough (DRE). All treatments were administered for the final 11 days of feeding. On supplementation d 10, barrows individually experienced a performance test at 1.09 m/s until they were subjectively exhausted. Wireless electromyography (EMG) sensors were affixed to the biceps femoris (BF), tensor fascia latae (TFL), and semitendinosus (ST) to measure real-time muscle activity. There were no treatment effects for barrow speed (p = 0.57), a tendency for a treatment effect (p = 0.07) for distance, and a treatment effect (p = 0.04) on time to exhaustion. Barrows of the 15NR and DRE treatments had greater (p = 0.05) distances to exhaustion than CON barrows but did not differ from other NR barrows (p > 0.11). Barrows in the 45NR treatment did not differ (p = 0.11) in distance from 30NR barrows but tended to have a greater (p = 0.07) distance compared to CON barrows. All other treatment comparisons did not differ (p > 0.27). Barrows in the DRE treatment moved for longer (p < 0.01) than CON barrows, but all other treatments did not differ from each other (p > 0.15). There was no treatment × period interaction for all muscles’ root mean square (RMS) values (p > 0.16), but there were Period effects for all muscles (p < 0.01) and a Treatment effect (p = 0.04) in the TFL. For all muscles, period 4 had greater RMS values than all other periods (p < 0.01), who did not differ from each other (p > 0.29). In the TFL, CON barrows had greater RMS values during the performance test compared to all NR treatments (p < 0.02), who did not differ from each other (p > 0.18). Overall, NR demonstrates potential in being a useful tool in fatigue prevention, but efficient administration of the compound needs further investigation.

The objective of this study was to collect and interpret three-axis acceleration, temperature, and relative humidity data from six locations within commercial transport trailers shipping market-weight pigs. Transport was observed in Kansas (n = 15) and North Carolina (n = 20). Prior to loading, three-axis accelerometers were affixed to six locations on the trailers: top fore (TF), top center (TC), top aft (TA), bottom fore (BF), bottom center (BC), and bottom aft (BA) compartments. Data were post-processed to calculate root-mean-square (RMS) accelerations and vibration dose values (VDV) in the vertical direction and the horizontal plane. These values were compared with exposure action values (EAV) and exposure limit values (ELV), vibration levels deemed uncomfortable and potentially dangerous to humans. Additionally, RMS and VDV were compared among the trailer compartments. The vertical RMS accelerations for all compartments exceeded the EAV for loads measured in Kansas, and for the majority of the compartments measured in North Carolina. Many compartments, specifically the BA compartment from all trips, exceeded the vertical ELV. Regardless of where the data were collected, fewer compartments exceeded the EAV in the horizontal orientation. Only BA compartments exceeded the ELV in the horizontal orientation. There were Area × Level interactions for vertical and horizontal RMS and VDV (P < 0.01). The BF compartment had a greater vertical RMS value than the TF, TC, and BC (P < 0.02) compartments, but did not differ (P = 0.06) from the TA compartment. The vertical RMS of the TA compartment did not differ from the TF, TC, and BC compartments (P > 0.13). The BF compartment had a greater (P = 0.02) vertical VDV value than the TC location, but did not differ from the other locations (P > 0.16). All other locations did not differ in vertical VDV (P > 0.12). The BF compartment had greater horizontal RMS than the TC and TA compartments (P < 0.01), but did not differ from TF and BC compartments (P > 0.12). All other compartments did not differ in horizontal RMS (P > 0.34). All compartments, aside from the BA compartment, did not differ in horizontal VDV (P > 0.19). Vibration analyses indicated the BA compartment had the greatest vertical and horizontal vibrations and a large percentage of the compartments exceed the EAV and ELV, which indicated pigs may have experienced uncomfortable trips that could cause discomfort or fatigue.

The objective of this study was to measure and examine 3-axis acceleration data from 6 locations within commercial transport trailers shipping market pigs. Over winter months (December through February) of 2018 to 2019 and 2019 to 2020, 16 pot-belly and 14 straight-deck trailer loads of market pigs were measured from 2 producers located in Kansas and North Carolina, respectively. Six accelerometers were placed in protective cases and affixed to the underside of the floor in the approximate center of the front compartment, middle of the trailer, and back compartment of the top and bottom decks. Data were post-processed to calculate power spectral density (PSD) functions and corresponding root mean square (RMS) accelerations. The PSDs lend insight into the vibrational frequency content of the trailers, while the RMS values indicate the severity of the vibration over the duration of each trip. With the exception of the lower aft portion of the trailer where levels are significantly higher, RMS values were consistent across trips and largely similar between sensor location and axis. Accelerations ranged between 0.06 and 0.18 g and varied in time, indicating data were non-stationarity. The PSD results reveal a largely broadband frequency response of the loaded trailers between 0 and 50 Hz, especially for sensors on the lower deck. Preliminary analysis of the data indicates the severity of vibrations experienced by pigs during transport would be considered uncomfortable by humans.

Twenty calves were placed on study at 3 days of age and were placed according to birth order into one of two groups: SS, which received 0.05% BW sodium zeolite A (SZA) added to their milk replacer, and CO, which received only milk replacer. Blood samples were taken on days 0, 30, and 60 for osteocalcin (OC) and deoxypyridinoline (DPD) analysis. On day 60, the calves were euthanized, and synovial fluid, articular cartilage, and both fused metacarpals were collected for bone quality analyses such as architecture and mechanical properties, mineral composition, and glycosaminoglycan concentration. There were no differences in OC concentrations because of treatment (p = 0.12), and CO calves had lower DPD concentrations than SS calves (p = 0.01), but the OC-to-DPD ratio was not different between treatments (p = 0.98). No differences in bone architecture or mechanical properties were detected. SZA supplementation increased cortical bone (p = 0.0002) and articular cartilage (p = 0.05) aluminum content. Glycosaminoglycan concentrations were not different in synovial fluid or cartilage. Supplementation of SZA appeared to alter the rate of bone turnover without altering bone strength. Aluminum concentrations in the bone and cartilage increased, which may be a concern, although the long-term consequences of such remain to be determined.

The objective was to determine the effects of sodium zeolite A (SZA) on mineral metabolism and tissue mineral composition in calves. Twenty calves were placed on study at 3 days of age and were placed into one of two groups: SS, which received 0.05% BW SZA added to their milk replacer, and CO, which received only milk replacer. Blood samples were taken on days 0, 30, and 60 for mineral analysis. Urine and feces were collected on day 30 for mineral metabolism, and on day 60, the calves were euthanized, and samples were taken from numerous organs for mineral analyses. Aluminum retention was increased in the SS calves (p = 0.001). Silicon concentrations were increased in the aorta, spleen, lung, muscle, and kidney of the SS calves, and aluminum was increased in all SS tissues (p < 0.05). Calcium concentrations were increased in aorta, liver, muscle, and tendon; phosphorus concentrations were increased in aorta, but decreased in plasma; magnesium concentrations were increased in aorta, heart, kidney, liver, and pancreas, but decreased in plasma; and iron concentrations were decreased in kidney and liver (p < 0.05). The accumulation of tissue aluminum and therefore potential adverse consequences may preclude any benefits of using SZA as a dietary supplement.

Silicon appears to be an essential element for proper endochondral ossification and glycosaminoglycan synthesis. Osteochondrosis (OC) is characterized by disturbed endochondral ossification, and glycosaminoglycan loss has been reported in OC lesions. Therefore, silicon may be effective in reducing OC lesions. The objective of the study was to evaluate the effects of supplemental silicon on OC lesion size. Initial radiographs were taken on 2-year-old Standardbreds (n = 44) on private facilities to identify OC defects in the distal third metacarpus/tarsus or osteochondral fragments at the dorsal aspect of the joint and defects/fragments at the distal tibia and on the trochlear ridges of the talus. Only clinically sound horses were included. Follow-up radiographs were taken at 120 days. Radiographs were digitized and the length and height of the OC defects/fragments were measured. Horses meeting study-inclusion requirements (n = 8) were pair-matched by facility and affected joint(s) and assigned to a group: control (receiving 200 g whole grain flour) and silicon supplemented (receiving 200 g bioavailable silicon source). Treatments were top-dressed on the feed for 120 days. Due to the onset of lameness, four horses did not complete the 120-day study duration. There was no effect (P>0.22) of treatment, time or treatment × time on lesion length, height or area. Silicon supplementation did not alter the radiographic appearance of OC lesions. Future research should focus on the effects of a silicon supplement on the prevention of OC lesions.

The objective of this study was to determine the efficacy of supplementation of Dynamic Trio 50/50, a bee pollen-based product, to improve physical fitness, blood leukocyte profiles, and nutritional variables in exercised horses. Ten Arabian horses underwent a standardised exercise test (SET), then were pair-matched by sex and fitness and randomly assigned to BP (receiving 118 g of Dynamic Trio 50/50 daily) or CO (receiving 73 g of a placebo) for a period of 42 days. A total collection was conducted from days 18 to 21 on six geldings to determine nutrient retention and neutral detergent fibre (NDF) and acid detergent fibre (ADF) digestibility. Horses were exercise conditioned and completed another SET on day 42. V160 and V200 were calculated from SET heart rates (HR). Lactate, glucose, haematocrit (HT) and haemoglobin (HB) concentrations were determined from SET blood samples. Total leukocyte count, and circulating numbers of various leukocytes and IgG, IgM and IgA concentrations were determined in rest and recovery blood samples from both SETs. Geldings on BP (n = 3) ate more feed than CO. BP had less phosphorus excretion, and tended to retain more nitrogen. BP tended to digest more NDF and ADF while having lower NDF digestibility and tending to have lower ADF digestibility. No treatment differences existed for V160 and V200, HR, lactate, HT and HB. There was a trend for lymphocyte counts to be lower in BP than CO on day 42. Dynamic Trio 50/50 supplementation may have a positive effect on performance by helping horses in training meet their potentially increased nutrient demands by increasing feed intake and thus nutrient retention.