Engineering water exchange is a safe and effective method for magnetic resonance imaging in diverse cell types.

Aquaporin-1 (Aqp1), a water channel, has garnered significant interest for cell-based medicine and in vivo synthetic biology due to its ability to be genetically encoded to produce magnetic resonance signals by increasing the rate of water diffusion in cells. However, concerns regarding the effects of Aqp1 overexpression and increased membrane diffusivity on cell physiology have limited its widespread use as a deep-tissue reporter. In this study, we present evidence that Aqp1 generates strong diffusion-based magnetic resonance signals without adversely affecting cell viability or morphology in diverse cell lines derived from mice and humans. Our findings indicate that Aqp1 overexpression does not induce ER stress, which is frequently associated with heterologous expression of membrane proteins. Furthermore, we observed that Aqp1 expression had no detrimental effects on native biological activities, such as phagocytosis, immune response, insulin secretion, and tumor cell migration in the analyzed cell lines. These findings should serve to alleviate any lingering safety concerns regarding the utilization of Aqp1 as a genetic reporter and should foster its broader application as a noninvasive reporter for in vivo studies.

Mechanical environment influences muscle activity during infant rolling.

An infant's musculoskeletal and motor development is largely affected by their environment. Understanding how different mechanical environments affect an infant's movements and muscle use is necessary to inform the juvenile products industry and reduce incidents involving inclined nursery products each year. The purpose of this study was to determine how the coordinated movements and corresponding muscle activation patterns are affected by different mechanical environments, specifically the back incline angle. Thirty-eight healthy infants (age: 6.5 ± 0.7 months; 23 M/15 F) were enrolled in this IRB-approved in-vivo biomechanics study. Surface electromyography sensors recorded muscle activity of the erector spinae, abdominal muscles, quadriceps, and hamstrings while infants rolled in five different mechanical environments: a flat surface and four device configurations representing a range of inclines infants are commonly exposed to. Coordinated movements were determined using video. In all configurations featuring an inclined seatback angle, infants experienced significantly higher erector spinae muscle activation and significantly lower abdominal muscle activation compared to the flat surface. Infants also exhibited a different coordinated movement featuring spinal extension and a pelvic thrust in the inclined device configurations that was not previously observed on the flat surface alone. Understanding how infants coordinate their movements and use their muscles during rolling in different inclined environments provides more insight into motor development and may inform the juvenile products industry. Many factors impact an infant's movements, therefore future work should explore how other environmental interactions influence an infant's movements and muscle activation, particularly for rolling.

Chronic Migraine May Be Associated With Postprandial Hypoglycemia in Adult Men: A Case Series.

Migraine is a common neurological disorder that significantly impacts patients around the world. In the United States, one in six individuals suffers from a migraine disorder. Despite its high prevalence, the etiology of migraine is not well understood. Multiple factors likely contribute to the development of both acute and chronic migraine, making the consensus as to the cause and treatment difficult. Presented here are three case studies involving adult males suffering from chronic migraine. Each subject provided a medical history and underwent physical, psychological, and neurological examinations. In addition, relevant bloodwork and cervical spine X-rays were obtained. Physical examination, laboratory studies, imaging, and psychological metrics were unremarkable with the notable exception of the three-hour oral glucose tolerance tests. All three patients displayed hypoglycemia at three hours. Furthermore, their symptoms markedly improved with the initiation of a ketogenic diet. These data are suggestive of a potential link between postprandial hypoglycemia and chronic migraine. Despite the small sample size, we feel that this report presents possible evidence for a connection between postprandial hypoglycemia and chronic migraine. Furthermore, properly controlled studies of larger sample sizes are required, but we suggest that clinicians consider screening patients for this easily overlooked metabolic disturbance, especially in the absence of other options.

Muscle activation and coordinated movements of infant rolling.

Rolling is a critical step of infant development, encouraging muscle coordination and enabling independent exploration. Understanding muscle activity during infant rolling movements on a flat surface is necessary to more fully characterize how the rolling milestone is achieved. The purpose of this study was to determine infants' muscle activation throughout roll initiation for six previously established coordinated movements. Thirty-eight healthy infants (age: 6.5 ± 0.7 months; 23M/15F) were enrolled in this IRB-approved in-vivo biomechanics study. Surface electromyography sensors recorded muscle utilization from the erector spinae, abdominal muscles, quadriceps, and hamstrings while infants rolled. Each rolling movement was categorized as one of six roll types, and the mean muscle activity was analyzed. All roll types required initial activation of all measured muscle groups. Movements featuring axial rotation of the torso relative to the pelvis required highly active erector spinae muscles. Movements featuring trunk and hip flexion required highly active abdominal muscles. Infants used distinct coordinated muscle activations to achieve the six different roll types on a flat surface. A foundational understanding of the different muscle activation patterns required during infant rolling will provide crucial insight into motor development. This study quantified muscle coordination required of infants to achieve rolling on a firm flat surface. Previous research indicates that the mechanical environment in which an infant is placed impacts muscle activity and body position during normal lying. Therefore, future work should explore if mechanical environments that differ from a flat and firm surface also influence these coordinated movements and muscle activations.

Engineering water exchange is a safe and effective method for magnetic resonance imaging in diverse cell types.

Aquaporin-1 (Aqp1), a water channel, has garnered significant interest for cell-based medicine and in vivo synthetic biology due to its ability to be genetically encoded to produce magnetic resonance signals by increasing the rate of water diffusion in cells. However, concerns regarding the effects of Aqp1 overexpression and increased membrane diffusivity on cell physiology have limited its widespread use as a deep-tissue reporter. In this study, we present evidence that Aqp1 generates strong diffusion-based magnetic resonance signals without adversely affecting cell viability or morphology in diverse cell lines derived from mice and humans. Our findings indicate that Aqp1 overexpression does not induce ER stress, which is frequently associated with heterologous expression of membrane proteins. Furthermore, we observed that Aqp1 expression had no detrimental effects on native biological activities, such as phagocytosis, immune response, insulin secretion, and tumor cell migration in the analyzed cell lines. These findings should serve to alleviate any lingering safety concerns regarding the utilization of Aqp1 as a genetic reporter and should foster its broader application as a noninvasive reporter for in vivo studies.

The effect of shoulder prosthesis stem length on failure due to torsional loading. A biomechanical study in composite humeri.

Background: Shoulder arthroplasty is becoming increasingly common. With evolving implant designs, multiple humeral stem options exist for the surgeon to choose from. New stemless and short-stem systems are modular, remove less native bone stock, and better adapt to patient anatomy. It has been suggested that shorter stem implants may be protective against periprosthetic fracture; however, this has not been mechanistically evaluated. Therefore, this study aimed to biomechanically test synthetic humeri with long-stem, short-stem, and stemless arthroplasty components in a torsional manner to evaluate their response to loading and characterize failure. Methods: Twenty-four synthetic humeri were implanted with long stem, short stem, or stemless uncemented prosthesis, 8 in each group. Humeri were mounted in a custom testing jig with a morse taper interfacing with a mechanical testing system. After a 20N axial force, specimens were torsionally loaded to failure at 15 degrees/sec, with 50 Hz collection. Torque vs. rotation curves were generated for each specimen, and stiffness, yield, ultimate strength, and failure load were measured. ANOVA and post hoc pairwise comparisons were used to assess effect of stem type on mechanical test variable. The association of the stem type with fracture type was analyzed by a Fisher's Exact test. Statistical significance was set at P < .05. Results: During torsional loading, long-stem implants were significantly stiffer than short or stemless implants. The angle of implant yielding was similar across stem designs; however, stemless implants had a lower yield torque. This correlated with a decreased yield energy in stemless compared to short stems as well. Maximum torque and failure torque was also significantly higher in short-stem and long-stem implants compared to stemless. Discussion: Periprosthetic fractures in shoulder arthroplasty are a concern in low-energy trauma, and stem design likely plays a significant role in early implant-bone failure. Our results suggest stemless implants under torsional load fail at lower stress and are less stiff than stemmed implants. The failure mechanism of stemless implants through metaphyseal cancellous bone emphasizes the effect bone quality has on implant fixation. There is likely a balance of torsional stability to survive physiologic loads while minimizing diaphyseal stress and risk of diaphyseal periprosthetic fracture. This combined with revision and fixation options represent decisions the surgeon is faced with when performing shoulder arthroplasty.

Leveraging DNA Origami to Study Phagocytosis.

Many plasma membrane receptors and ligands form nanoscale clusters on the plasma membrane surface. However, methods for directly and precisely manipulating nanoscale protein localization are limited, making understanding the effects of this clustering difficult. DNA origami allows precise control over nanoscale protein localization with high fidelity and adaptability. Here, we describe how we have used this technique to study how nanoscale protein clustering affects phagocytosis. We provide protocols for conjugating DNA origami structures to supported lipid bilayer-coated beads to assay phagocytosis and planar glass coverslips for TIRF microscopy. The core aspects of this protocol can be translated to study other immune signaling pathways and should enable the implementation of previously inaccessible investigations.

Barriers and facilitators of weight bearing after hip fracture surgery among older adults. A scoping review.

PURPOSE: This scoping review aimed to synthesise the available evidence on barriers and facilitators of weight bearing after hip fracture surgery in older adults. METHODS: Published (Cochrane Central, MEDLINE, EMBASE, CINAHL, and PEDro) and unpublished (Global Health, EThOS, WorldCat dissertation and thesis, ClinicalTrials.gov , OpenAIRE, DART-Europe) evidence was electronically searched from database inception to 29 March 2022. Barriers and facilitators of weight bearing were extracted and synthesised into patient, process (non-surgical), process (surgical), and structure-related barriers/facilitators using a narrative review approach. RESULTS: In total, 5594 were identified from the primary search strategy, 1314 duplicates were removed, 3769 were excluded on title and abstract screening, and 442 were excluded on full-text screening. In total, 69 studies (all from published literature sources) detailing 47 barriers and/or facilitators of weight bearing were included. Of barriers/facilitators identified, 27 were patient-, 8 non-surgical process-, 8 surgical process-, and 4 structure-related. Patient facilitators included anticoagulant, home discharge, and aid at discharge. Barriers included preoperative dementia and delirium, postoperative delirium, pressure sores, indoor falls, ventilator dependence, haematocrit < 36%, systemic sepsis, and acute renal failure. Non-surgical process facilitators included early surgery, early mobilisation, complete medical co-management, in-hospital rehabilitation, and patient-recorded nurses' notes. Barriers included increased operative time and standardised hip fracture care. Surgical process facilitators favoured intramedullary fixations and arthroplasty over extramedullary fixation. Structure facilitators favoured more recent years and different healthcare systems. Barriers included pre-holiday surgery and admissions in the first quarter of the year. CONCLUSION: Most patient/surgery-related barriers/facilitators may inform future risk stratification. Future research should examine additional process/structure barriers and facilitators amenable to intervention. Furthermore, patient barriers/facilitators need to be investigated by replicating the studies identified and augmenting them with more specific details on weight bearing outcomes.

An Individualized Multi-Modal Approach for Detection of Medication "Off" Episodes in Parkinson's Disease via Wearable Sensors.

The primary treatment for Parkinson's disease (PD) is supplementation of levodopa (L-dopa). With disease progression, people may experience motor and non-motor fluctuations, whereby the PD symptoms return before the next dose of medication. Paradoxically, in order to prevent wearing-off, one must take the next dose while still feeling well, as the upcoming off episodes can be unpredictable. Waiting until feeling wearing-off and then taking the next dose of medication is a sub-optimal strategy, as the medication can take up to an hour to be absorbed. Ultimately, early detection of wearing-off before people are consciously aware would be ideal. Towards this goal, we examined whether or not a wearable sensor recording autonomic nervous system (ANS) activity could be used to predict wearing-off in people on L-dopa. We had PD subjects on L-dopa record a diary of their on/off status over 24 hours while wearing a wearable sensor (E4 wristband®) that recorded ANS dynamics, including electrodermal activity (EDA), heart rate (HR), blood volume pulse (BVP), and skin temperature (TEMP). A joint empirical mode decomposition (EMD) / regression analysis was used to predict wearing-off (WO) time. When we used individually specific models assessed with cross-validation, we obtained > 90% correlation between the original OFF state logged by the patients and the reconstructed signal. However, a pooled model using the same combination of ASR measures across subjects was not statistically significant. This proof-of-principle study suggests that ANS dynamics can be used to assess the on/off phenomenon in people with PD taking L-dopa, but must be individually calibrated. More work is required to determine if individual wearing-off detection can take place before people become consciously aware of it.

Residual limb strength and functional performance measures in individuals with unilateral transtibial amputation.

BACKGROUND: Individuals with lower limb amputation exhibit lower residual limb strength compared to their sound limb. Deficits in residual limb knee flexion and extension strength may impact functional performance during tasks relevant to daily living. RESEARCH QUESTION: Does knee flexor and extensor strength in the residual limb impact functional outcome measures, such as walking energetics and performance metrics, in individuals with unilateral transtibial amputation? METHODS: Fourteen individuals with traumatic unilateral transtibial amputation were recruited for this observational study. Participants completed metabolic testing at three standardized speeds based on leg length, as well maximum isokinetic knee flexion and extension strength for both residual and sound limbs. Participants also completed a series of functional outcome tests, including a two-minute walk test, timed stair ascent test, and four-square step test. Walking energetics (metabolic cost, heart rate, and rating of perceived exertion) and performance metrics were compared to percent deficit of residual limb to sound limb knee flexion and extension muscle strength. A linear regression assessed significant relationships (p < 0.05). RESULTS: A significant relationship was observed between percent deficit of knee extension strength and heart rate (p = 0.024) at a fast walking speed. Additionally, percent deficit knee flexion strength related to rating of perceived exertion at slow and moderate walking speeds (p = 0.038, p = 0.024). Percent deficit knee extension strength related to two-minute walk time performance (p = 0.035) and percent deficit knee flexion strength related to timed stair ascent time (p = 0.025). SIGNIFICANCE: These findings suggest the importance of strength retention of the residual limb knee flexion and extension musculature to improve certain functional outcomes in individuals with unilateral transtibial amputation.

Effect of Custom Carbon Ankle-Foot Orthosis Use on Energetic Demands of Walking and Comparisons With Individuals With Amputation.

OBJECTIVE: To compare the metabolic demands of walking in individuals with lower limb injury with and without ankle-foot orthosis (AFO) use. A secondary aim was to compare these results with those from individuals with unilateral transtibial amputation (TTA) and able-bodied controls. DESIGN: Cross-sectional study. SETTING: Two clinical research centers. PARTICIPANTS: Thirteen individuals (N=13) with lower limb injury who used a passive-dynamic AFO underwent metabolic analysis at 3 standardized speeds with and without their AFO. Results were compared with individuals with unilateral TTA who used a passive prosthetic foot and able-bodied controls with no musculoskeletal, neurologic, or cardiovascular deficits. MAIN OUTCOME MEASURES: Oxygen consumption, heart rate, and rating of perceived exertion. RESULTS: The use of the passive-dynamic AFO did not significantly change energetic demand (oxygen consumption, heart rate, perceived exertion) in participants with a lower limb [LL] injury. Heart rate (P<.037) was significantly greater than able-bodied controls, but perceived exertion was significantly lower (P≤.031). There were no significant differences between participants with an LL injury (with or without the AFO) and individuals with TTA. CONCLUSIONS: Many individuals with LL injuries may expect to use passive-dynamic AFOs with little to no metabolic consequence. The stabilizing and assistive benefits of the AFO likely balance with its well-known range of motion limitations and power reductions. Passive-dynamic AFO use can sometimes be an alternative for individuals considering TTA. These results support that AFO users may be able to achieve similar energetic demands as those with amputation.

Probing the nature of donor-acceptor effects in conjugated materials: a joint experimental and computational study of model conjugated oligomers.

A series of model oligomers consisting of combinations of a traditional strong donor unit (3,4-ethylenedioxythiophene), a traditional strong acceptor unit (benzo[c][1,2,5]thiadiazole), and the ambipolar unit thieno[3,4-b]pyrazine were synthesized via cross-coupling methods. The prepared oligomers include all six possible dimeric combinations in order to characterize the extent and nature of donor-acceptor effects commonly used in the design of conjugated materials, with particular focus on understanding how the inclusion of ambipolar units influences donor-acceptor frameworks. The full oligomeric series was thoroughly investigated via photophysical and electrochemical studies, in parallel with density functional theory (DFT) calculations, in order to correlate the nature and extent of donor-acceptor effects on both frontier orbital energies and the desired narrowing of the HOMO-LUMO energy gap. The corresponding relationships revealed should then provide a deeper understanding of donor-acceptor interactions and their application to conjugated materials.

Effect of Sex and Ankle Brace Design on Knee Biomechanics During a Single-Leg Cut.

BACKGROUND: Despite success at preventing ankle sprain, prophylactics that restrict ankle plantarflexion motion may produce deleterious knee biomechanics and increase injury risk. PURPOSE: To determine if ankle prophylactics that restrict plantar- and dorsiflexion motion produce changes in knee biomechanics during a single-leg cut and whether those changes differ between sexes. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 17 male and 17 female participants performed a single-leg cut with 4 conditions: Ankle Roll Guard (ARG), lace-up brace, nonelastic tape, and an unbraced control. Peak stance knee flexion, abduction, and internal rotation joint angle and moment; total knee reaction moment (TKM) and its components (sagittal, frontal, and transverse); and ankle plantarflexion and inversion range of motion (ROM) and peak stance joint moments were tested with a repeated measures analysis of variance to determine the main effect and interaction of condition and sex. RESULTS: Brace and tape restricted plantarflexion ROM as compared with ARG and control (all P < .001). With the brace, women had increased peak knee abduction angle versus ARG (P = .012) and control (P = .009), and men had decreased peak knee internal rotation moment as compared with ARG (P = .032), control (P = .006), and tape (P = .003). Although the restrictive tape decreased inversion ROM when compared with ARG (P = .004) and brace (P = .017), it did not change knee biomechanics. Neither brace nor tape produced significant changes in TKM or components, yet sagittal TKM increased with ARG versus control (P = .016). Women exhibited less ankle inversion ROM (P = .003) and moment (P = .049) than men, while men exhibited significantly greater frontal TKM (P = .022) and knee internal rotation moment with the ARG (P = .029), control (P = .007), and tape (P = .016). CONCLUSION: Prophylactics that restrict ankle plantarflexion motion may elicit knee biomechanical changes during a single-leg cut, but these changes may depend on prophylactic design and user's sex and may increase women's injury risk. CLINICAL RELEVANCE: Sex-specific ankle prophylactic designs may be warranted to reduce knee injury during sports.

Effectiveness of Novel Ankle Prophylactic Compared With Lace-Up Brace or Tape.

CONTEXT: Conventional ankle prophylactics restrict harmful ankle inversion motions that lead to injury. But these existing prophylactics also limit other ankle motions, potentially leading to detriments in functional joint capacity. The ankle roll guard (ARG) may alleviate the prevailing issues of existing ankle prophylactics and prevent harmful ankle inversion, while allowing other joint motions. OBJECTIVE: This technical report sought to compare the ARG's ability to prevent ankle inversion, but not restrict other ankle motions with existing prophylactics. DESIGN: Repeated-measures study. SETTING: Motion capture laboratory. PARTICIPANTS: Thirty participants. INTERVENTION: Each participant had dominant limb ankle kinematics recorded during 5 successful trials of a sudden inversion event and 30-cm drop landing task with each of 4 conditions (ARG, ASO ankle stabilizer [brace], closed-basket weave athletic tape [tape], and unbraced [control]). MAIN OUTCOME MEASURES: Peak ankle inversion angle, range of inversion motion (ROM), and time to peak inversion during the sudden inversion event, and ankle plantar- and dorsiflexion ROM during the drop landing were submitted to a 1-way repeated-measures analysis of variance to test the main effect of prophylaxis. RESULTS: Participants exhibited greater inversion ROM with control compared with tape (P = .001), and greater plantar- and dorsiflexion ROM with ARG and control compared with brace (P = .02, P = .001) and tape (P = .02, P < .001). It took significantly longer to reach peak ankle inversion with brace and tape compared with ARG (P < .001, P = .001) and control (P = .01, P = .01). No significant difference in peak ankle inversion was observed between any condition (P > .05). CONCLUSION: The ARG may prevent ankle inversion angles where injury is thought to occur (reportedly >41°), but is less restrictive than existing prophylactics. The less restrictive ARG may make its use ideal during rehabilitation as it allows ankle plantar- and dorsiflexion motions, while preventing inversion related to injury.

Validation of a custom spine biomechanics simulator: A case for standardization.

Mechanical testing machines used in cadaveric spine biomechanics research vary between labs. It is a necessary first step to understand the capabilities and limitations in any testing machine prior to publishing experimental data. In this study, a reproducible protocol that uses a synthetic spine was developed and used to quantify the inherent rotation error and the ability to apply loads in a single physiologic plane (pure-moment) of a custom spine biomechanics simulator. Rotation error was evaluated by comparing data collected by the test machine and the data collected by an optical motion capture system. Pure-moment loading was assessed by comparing the out-of-plane loads to the primary plane load. Using synthetic functional spine units previously shown to have mechanics similar to the cadaveric human spine, the simulator was evaluated using a dynamic test protocol reflective of its future use in the study of cadaveric spine specimens. Rotation errors inherent in the test machine were <0.25° compared to motion capture. Out of plane loads were <4.0% of the primary plane load, which confirmed pure-moment loading. The authors suggest that a standard validation protocol for biomechanical spine testing machines is needed for transparency and accurate field-wide data interpretation and comparison. We offer recommendations based on the reproducible use of a synthetic spinal specimen for consideration.

ProDOT-Assisted Isomerically Pure Indophenines.

Reactions between 3,4-propylenedioxythiophenes (ProDOTs) and N-alkyl isatins under ambient conditions result in isomerically pure indophenine materials as confirmed by TLC and 1H NMR analysis. The resulting low band gap materials exhibit favorable inter- and intramolecular interactions, high thermal stabilities, low energy electronic transitions, and amphoteric redox behavior.

Inequity in rehabilitation interventions after hip fracture: a systematic review.

OBJECTIVE: to determine the extent to which equity factors contributed to eligibility criteria of trials of rehabilitation interventions after hip fracture. We define equity factors as those that stratify healthcare opportunities and outcomes. DESIGN: systematic search of MEDLINE, Embase, CINHAL, PEDro, Open Grey, BASE and ClinicalTrials.gov for randomised controlled trials of rehabilitation interventions after hip fracture published between 1 January 2008 and 30 May 2018. Trials not published in English, secondary prevention or new models of service delivery (e.g. orthogeriatric care pathway) were excluded. Duplicate screening for eligibility, risk of bias (Cochrane Risk of Bias Tool) and data extraction (Cochrane's PROGRESS-Plus framework). RESULTS: twenty-three published, eight protocol, four registered ongoing randomised controlled trials (4,449 participants) were identified. A total of 69 equity factors contributed to eligibility criteria of the 35 trials. For more than 50% of trials, potential participants were excluded based on residency in a nursing home, cognitive impairment, mobility/functional impairment, minimum age and/or non-surgical candidacy. Where reported, this equated to the exclusion of 2,383 out of 8,736 (27.3%) potential participants based on equity factors. Residency in a nursing home and cognitive impairment were the main drivers of these exclusions. CONCLUSION: the generalisability of trial results to the underlying population of frail older adults is limited. Yet, this is the evidence base underpinning current service design. Future trials should include participants with cognitive impairment and those admitted from nursing homes. For those excluded, an evidence-informed reasoning for the exclusion should be explicitly stated. PROSPERO: CRD42018085930.

Crystal structure and Hirshfeld analysis of 2-(5-bromo-thio-phen-2-yl)aceto-nitrile.

The title compound, C6H4BrNS, crystallizes in the space group P21/n with one complete mol-ecule in the asymmetric unit. The non-H atoms are nearly planar (r.m.s for non-H atoms = 0.071 Å), with the nitrile group oriented anti-periplanar with respect to the thio-phene S atom. Inter-molecular Type I centrosymmetric Br⋯Br halogen inter-actions are present at a distance of 3.582 (1) Šand with a C-Br⋯Br angle of 140.7 (1)°. Additional weaker C-H⋯N, C-H⋯S, and S⋯π inter-actions are also present. A Hirshfeld analysis indicates Br⋯Br inter-actions comprise only 1.9% of all the inter-atomic contacts.

Effects of magnesium source and monensin on nutrient digestibility and mineral balance in lactating dairy cows.

The interaction of monensin and 2 supplemental Mg sources (MgO and MgSO4) on total-tract digestion of minerals and organic nutrients and milk production was evaluated in lactating dairy cattle. Eighteen multiparous Holstein cows (139 ± 35 DIM) were used in a split-plot experiment with 0 or 14 mg/kg diet DM of monensin as the whole-plot treatments and Mg source as split-plot treatments. During the entire experiment (42 d), cows remained on the same monensin treatment but received a different Mg source in each period (21 d) of the Latin square. Diets were formulated to contain 0.35% Mg with about 40% of that provided by MgO or MgSO4. Diets were formulated to have similar concentrations of major nutrients and K concentrations were elevated (2.1% of DM) with K2CO3 to create antagonism to Mg absorption. Apparent digestibility was measured by total collection of urine and feces. Supplemental MgSO4 decreased DMI (26.9 vs. 25.7 kg/d) and tended to decrease milk yield (40.2 vs. 39.3 kg/d), but increased the digestibility of OM (68.3 vs. 69.2%) and starch (91.9 vs. 94.4%) compared with MgO. Feeding MgSO4 with monensin decreased NDF digestibility compared with other treatments (46.7 vs. 50.2%). That diet also had decreased apparent absorption of Mg compared with diets without monensin (15.6 vs. 19.2%), whereas MgO with monensin had greater apparent absorption of Mg (23.0%) than other treatments. Cows consuming MgSO4 had increased apparent Ca absorption (32.2 vs. 28.1%) and balance. A diet with MgSO4 without monensin increased the concentration of long-chain fatty acids in milk, suggesting increased mobilization of body fat or decreased de novo fatty acid synthesis in the mammary gland. Overall, when dietary Mg was similar, MgO was the superior Mg source for lactating dairy cattle, but inclusion of monensin in diets should be considered when evaluating Mg sources.

Effect of including canola meal and supplemental iodine in diets of dairy cows on short-term changes in iodine concentrations in milk.

The dietary requirement for iodine is based on thyroxine production, but data are becoming available showing potential improvements in hoof health when substantially greater amounts of I are fed. Feeding high amounts of I, however, can result in the milk having excessive concentrations of I. Canola meal contains goitrogenic compounds that reduce the transfer of I into milk. We hypothesized that including canola meal in diets would allow high supplementation rates of I without producing milk with unacceptable concentrations of I. Thirty midlactation Holstein cows were fed a diet with all supplemental protein from soybean meal (0% of diet dry matter as canola meal) or with all supplemental protein from canola meal (13.9% canola meal). A third treatment has a mix of soybean meal and canola meal (3.9% canola meal). Within canola-meal treatment, cows were fed 0.5 or 2.0mg of supplemental I per kilogram of diet dry matter from ethylenediamine dihydroiodide. Cows were maintained on the canola treatment for the duration of the experiment but were changed from one I treatment to the other after 13d of receiving the treatment. Milk I concentration before the treatments started (cows fed 0.5mg/kg of I) averaged 272µg/L and increased within 22h after cows were first fed diets with 2mg/kg of I. As inclusion rate of canola meal increased, the concentration of I in milk decreased linearly. After 12d of supplementation, milk from cows fed 0.5mg/kg of I had 358, 289, and 169µg of I/L for the 0, 3.9%, and 13.9% canola-meal treatments. For cows fed 2.0mg/kg of I, milk I concentrations were 733, 524, and 408µg/L, respectively. Concentrations of I in serum increased with increased I supplementation, but the effect of canola meal was opposite of what was observed for milk I. Cows fed the highest canola-meal diets had the highest serum I whether cows were fed 0.5 or 2.0mg/kg of I. Feeding dairy cows diets with 13.9% canola meal maintained milk I concentrations below 500µg/L when diets were supplemented with 2mg/kg of I.