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Heat stress reduces reproductive efficiency in beef cattle. Recent evidence suggests that supplementation of red clover can alleviate the physiological impacts of fescue toxicosis which could decrease heat stress. Our objective was to determine the effect of supplementing heifers grazing endophyte-infected tall fescue (E+ TF) with a conventional mineral containing red-clover leaf. We hypothesized that heifers supplemented with the red-clover leaf mineral would have greater conception rates to AI (CRAI) in times of possible heat stress compared with heifers supplemented with conventional mineral. A grazing study was conducted from May - August in 2021, 2022, and 2023. Yearling beef heifers (n = 32, 36, 40 heifers yr-1, respectively) were blocked by body weight, hair coat score and color into 4 grazing blocks that were assigned to 1 of 2 treatments (2 blocks treatment-1): 1. conventional non-medicated loose mineral control (0%-RC), or 2. conventional loose mineral + 20% wt/wt red clover leaf (20%-RC). Mineral treatments were provided in ground, 3-compartment mineral feeders ad libitum. Each grazing block was assigned to four, 0.8- ha. pastures consisting of predominantly E+ TF and were rotationally managed over the course of the study. Each year estrus was synchronized suitable for fixed time AI in May and all heifers resynchronized in June. In addition, each heifer was fitted with an ear-tag sensor (CowManager SensOor, Agis Automatisering BV, Harmelen, the Netherlands) for continuous behavioral monitoring (including high activity and activity). The CRAI were analyzed with the GLIMMIX procedure of SAS using the binomial distribution link logit function (v.9.4., SAS Inst. Inc., Cary, NC). Total daily activity and high activity reported by CowManger during May and June were analyzed by the MIXED procedure with repeated measures of SAS. The CRAI were similar for 20%-RC (67.30 ± 9.80%) and 0%-RC (60.70 ± 9.80%) heifers following the first service of AI (P = 0.51) during a thermoneutral period in May. In contrast, CRAI was greater (P = 0.02) for 20%-RC heifers (48.67 ± 13.47%) than CM (15.10 ± 13.47%) in June when temperatures increased to potential heat stress levels. Overall, conception rate after two rounds of AI for 20%-RC (78.30 ± 9.30%) heifers tended to be greater (P = 0.08) than CM (62.20 ± 9.30 %). While high activity (associated with estrous behavior) reported by CowManager did not differ between treatments (20%-RC: 203.94; 0%-RC: 213.90; SEM: 8.65 min d-1; P = 0.25), normal daily activity of 20%-RC heifers (150.69 ± 10.40 min d-1) tended to be greater (P = 0.06) than CM (126.33 ± 8.65 min d-1). Results of this study suggest supplementing red-clover containing mineral may mitigate negative effects of consuming E+ TF including decreased conception rates during times of heat stress. [ABSTRACT FROM AUTHOR]

Summer annual grass‐legume mixtures may provide supplemental grazing for livestock when cool‐season pastures are less productive, but nitrogen fertilizer recommendations for these mixtures are not well established. Inputs to these systems are often high, so optimizing N fertilizer rates may increase appeal to producers. This study evaluated the effects of increasing botanical diversity and N fertilizer application on the yield and botanical composition of summer annual mixtures in four environments in Kentucky. Nitrogen fertilizer rates of 0, 56, 112, 168, and 224 kg N ha–1 were applied to a sudangrass [Sorghum bicolor (L.) Moench × Sorghum sudanese (P.) Stapf] monoculture, a three‐species mixture, and an 11‐species mixture. In three out of four environments, sward biomass increased as N application increased (average of 15 kg dry matter (DM) ha–1 increase per kg N ha–1; p <.05). Mixture complexity had no effect on forage DM accumulation in three out of four environments (4,000, 5,830, and 7,280 kg DM ha–1 averaged over mixture for three environments; p >.05). Mixtures were overwhelmingly dominated by grasses, resulting in low functional diversity. Legumes did not respond to N (p >.05), but their contribution to sward DM was <4%. Species compatibility should be a priority when utilizing multi‐species mixtures. If a stronger legume component is desired, care must be taken to provide management that favors these species, such as reduced grass‐seeding rates to limit competition, especially during initial establishment. Core Ideas: 224 kg N ha–1 increased yield by 1.9 times over no N in three out of four environments.Mixtures did not outyield monocultures and were dominated by high‐yielding species.Legumes are not competitive when planted with high seeding rates of summer annual grasses.Annual pastures should utilize compatible species to reduce competitive dominance. [ABSTRACT FROM AUTHOR]

Activation of the mechanistic target of rapamycin (mTOR)-controlled anabolic signaling pathways in skeletal muscle of rodents and humans is responsive to the level of dietary protein supply, with maximal activation and rates of protein synthesis achieved with 0.2 to 0.4 g protein/kg body weight (BW). In horses, few data are available on the required level of dietary protein to maximize protein synthesis for maintenance and growth of skeletal muscle. To evaluate the effect of dietary protein level on muscle mTOR pathway activation, five mares received different amounts of a protein supplement that provided 0, 0.06, 0.125, 0.25, or 0.5 g of crude protein (CP)/kg BW per meal in a 5 × 5 Latin square design. On each sample day, horses were fasted overnight and were fed only their protein meal the following morning. A preprandial (0 min) and postprandial (90 min) blood sample was collected and a gluteus medius muscle sample was obtained 90 min after feeding the protein meal. Blood samples were analyzed for glucose, insulin, and amino acid concentrations. Activation of mTOR pathway components (mTOR and ribosomal protein S6 [rpS6]) in the muscle samples was measured by Western immunoblot analysis. Postprandial plasma glucose (P = 0.007) and insulin (P = 0.09) showed a quadratic increase, while total essential amino acid (P < 0.0001) concentrations increased linearly with the graded intake of the protein supplement. Activation of mTOR (P = 0.02) and its downstream target, rpS6 (P = 0.0008), increased quadratically and linearly in relation to the level of protein intake, respectively. Comparisons of individual doses showed no differences (P > 0.05) between the 0.25 and 0.5 g of protein intake for either mTOR or rpS6 activation, indicating that protein synthesis may have reached near maximal capacity around 0.25 g CP/kg BW. This is the first study to show that the activation of muscle protein synthetic pathways in horses is dose-dependent on the level of protein intake. Consumption of a moderate dose of high-quality protein resulted in near maximal muscle mTOR pathway activation in mature, sedentary horses. [ABSTRACT FROM AUTHOR]

Since the 2018 Farm Bill, US growers have been allowed to cultivate hemp (Cannabis sativa L.), prompting interest in exploring the use of hemp products in ruminant diets. Extraction of cannabidiol (CBD) oil from hemp biomass generates spent inflorescent material that could be upcycled as a feedstuff, yet little is known about its fiber composition. A recent study measured in vitro true digestibility and fermentation parameters of multiple hemp cultivars, some intact and some CBD-extracted (Altman et al., 2022). Both categories of hemp inflorescence material had similar or greater total digestible nutrients (TDN) than an alfalfa cube control, supporting hemp's potential as a feedstuff. However, comparisons between non-extracted and CBD-extracted samples could not be made, and the fiber content was only described as neutral detergent fiber (NDF). Fiber composition can significantly impact ruminal digestibility, and in-depth characterizations of cell wall carbohydrate composition can provide further insight into the digestibility of a specific plantbased feed. Therefore, in the present study, we examined the effect of CBD oil extraction on the cell wall carbohydrate composition of the inflorescent material of two hemp cultivars. Intact (Biomass) and CBDextracted (Spent) inflorescent material from two hemp cultivars, Mary and Zelios, were analyzed. The scell wall monosaccharides of the samples were released via two complementary acid hydrolyses, methanolysis and Saeman (sulfuric acid) hydrolysis, and separated and quantified using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). Additionally, the carbohydrate linkage patterns were assessed by generating partially methylated alditol acetates (PMAAs). Student's unpaired t-tests were run in GraphPad Prism, and no differences (P > 0.05) in monosaccharide concentrations based upon treatment (CBD extraction) or cultivar were found with either hydrolysis method except for the methanolysis glucose concentration between the biomass forms of the two cultivars where Mary Biomass possessed more glucose than Zelios Biomass (P

Measures of temperament have been previously related to gain and intake in beef cattle. Intake effects may be partially mediated through social interactions in that some temperament measures may directly relate to social dominance behavior. To examine the relationships between temperament, growth, and social dominance behavior, thirty-two crossbred steers were used in a 56-d randomized complete block design experiment with a 2 × 2 factorial treatment structure. Temperament treatments (assigned on d −7) were chute exit velocity (EV; slow vs. fast) and objective chute score (OCS; low vs. high), a novel temperament measure, defined as the coefficient of variation of recorded weight values collected at five Hz for 10 s while an animal’s head was restrained in a chute. Electronic ear tags with accelerometers were used to continuously measure animal activity. Social dominance behaviors were quantified using video records of 2 h intervals directly following feeding for d 1–13. Dominance was calculated as average dominance index and David’s score. Jugular blood samples were collected to analyze antibody response to leptospirosis vaccines. There were no EV by OCS interactions (P ≥ 0.23) for average daily gain (ADG) or antibody titers. High OCS steers gained 0.26 kg/d more than low OCS steers (P < 0.01) and slow EV steers gained 0.12 kg/d more than fast EV steers (P = 0.02). Slow EV animals had an increased antibody response compared with fast EV animals (P = 0.05). Ranking in the dominance hierarchy was influenced by an EV × OCS interaction (P < 0.02), but there was not a linear relationship between dominance ranking and ADG. Low OCS steers tended to have higher daily activity counts than high OCS steers (P = 0.11), and fast EV steers had higher (P = 0.08) activity counts than slow EV steers. In conclusion, our two temperament-related measures, EV and OCS, were independently related to differences in ADG. Although dominance ranking was significantly related to the interaction of these two temperament measures, it was not linearly related to ADG. Alternatively, differences in accelerometer-based activity counts among temperament groups did correspond with trends in growth responses. [ABSTRACT FROM AUTHOR]

Ergot alkaloids, in their active isomeric form, affect animal health and performance, and adsorbents are used to mitigate toxicities by reducing bioavailability. Adsorbents with high specificity (molecularly imprinted polymers: MIP) adsorb ergot alkaloids in vitro, but require evaluation for biological implications. Using ex vivo myography, synthetic polymers were evaluated for effects on the bioactivity of ergotamine tartrate (ETA). Polymers were first evaluated using isotherms. Lateral saphenous veins were collected from 17 steers for four independent studies: dose response of ETA, adsorbent dose response, validation of pre-myograph incubation conditions and MIP/ non-molecularly imprinted polymer (NIP) comparison. Norepinephrine normalized percent contractile response to increasing ETA exhibited a sigmoidal dose response (max: 88.47 and log of the effective molar concentration (EC50) (-log [ETA]) of 6.66 ± 0.17 M). Although sample preparation time affected contractile response (p < 0.001), pre-myograph incubation temperature (39 vs. 21 °C, 1 h) had no effect (p > 0.05). Isothermal adsorption showed a maximum adsorption of 3.27E-008 moles·mg-1 and affinity between 0.51 and 0.57 mg (R2 : 0.83-0.92) for both polymers, with no significant difference between polymers (p > 0.05). No significant differences in maximum inhibitory (p = 0.96) and IC50 responses (p = 0.163) between MIP and NIP were noticed. Normalized percent contraction could be predicted from the in vitro adsorption data (R2 = 0.87, p < 0.01), for both polymers. These studies indicate that synthetic polymers are potentially effective adsorbents to mitigate ergot toxicity caused by ergot alkaloids, with little evidence of significant differences between MIP and NIP in aqueous media. [ABSTRACT FROM AUTHOR]

OBJECTIVE To test a unique electronic ear tag designed to collect movement data to determine whether physical activity of sick steers differed from that of healthy steers. ANIMALS 206 steers. PROCEDURES Physical activity in 2 groups of steers during November and December of 2010 (101 steers; the tag of I steer failed, and thus that steer was removed from the study, which resulted in data for 100 steers) and 201 1 (105 steers) was monitored with an electronic ear tag device with an on-board triple-axis accelerometer.The accelerometer recorded motion in all 3 axes in the form of counts per minute. A radio-frequency transmitter on the ear tag delivered serial packets of motion data to a local server. An algorithm was developed to analyze the activity data to determine whether this technique could be used to assess health status with high accuracy. RESULTS Steers that became sick had significantly fewer activity counts (approx 25% fewer), compared with the activity counts of steers that remained healthy the entire time. CONCLUSIONS AND CLINICAL RELEVANCE In this study, automated detection of health status in growing cattle was feasible through remote monitoring of animal activity. Early identification of sick animals should lead to improved health outcomes, increased marketability, and improved animal well-being and help to minimize the use of antimicrobials that could contribute to resistant bacteria. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if increasing forage botanical diversity improved stocker gains on warm-season annual (WSA) pastures. An opportunity exists to add extra gain on fall-born calves by grazing summer pastures after spring weaning and selling at a more favorable late summer market. However, cool-season perennial pastures in the Mid-South often have insufficient quality and yield to support desired summer gains. Therefore, the improved production and nutritive value of WSA forages shows promise in this system. A study was conducted near Princeton, KY, where calves (329, 366, and 297 kg in 2017, 2018, and 2019, respectively) grazed one of three WSA forage treatments without supplementation in a randomized complete block design with three replications. Treatments included 1) sorghum-sudangrass monoculture (MONO), 2) simple mixture (SIMPLE = sorghum-sudangrass, pearl millet, soybean), and 3) complex mixture (COMPLEX = SIMPLE + sudangrass, corn, crabgrass, cowpea, sunflower, sunn hemp, daikon radish, forage rape, Korean lespedeza). In 2017, MONO and SIMPLE calves had higher average daily gain (ADG) than COMPLEX calves (0.79 kg/day vs. 0.66 kg/day, P < 0.03). In 2018, no differences in ADG were detected among treatments (P > 0.3); however, calves only gained 0.01 kg/day. In 2019, MONO and SIMPLE calves again had higher ADG than COMPLEX calves (0.59 kg/day vs. 0.43 kg/day, P < 0.03). The exceptionally low 2018 ADG was likely due to the higher nutritional demand of heavier calves and the lower nutritive value of mature forages compared to other years. In conclusion, complex WSA forage mixtures did not offer any improvement in animal performance, and proper management of all WSA forages (maintaining a vegetative state) is paramount to achieving adequate gains on stockers without supplementation; however, supplementation may be necessary to improve WSA forage utilization in the rumen, potentially leading to more favorable gains. [ABSTRACT FROM AUTHOR]

Relationships of forage nutritive value (NVAL) and quantity with individual animal performance on pasture have long been evaluated, but there have been few attempts to describe the specific roles or relative importance of NVAL and quantity in determining animal response. The objective of this review was to more clearly define these roles based on a comprehensive assessment of pastureland literature and the application of a meta-analysis. It is clear that quantity and NVAL interact. When pastures present a wide range in forage mass, 60 to 90% of variation in average daily gain (ADG) can be explained by quantity, but there may be no relationship of NVAL with ADG. If pastures present only high forage mass, there may be no relationship between quantity and ADG, but NVAL may explain more than 50% of variation in ADG. The meta-analysis and a review of studies that evaluated forages of differing NVAL across a range of forage mass provided evidence that NVAL (i) sets the upper limit for ADG, (ii) determines the slope of the regression of ADG on stocking rate (SR), and (iii) establishes the forage mass at which ADG plateaus. In contrast, forage quantity determines the proportion of potential ADG that is achieved and is the primary driver for direction of the ADG response (negative) to increasing SR. Thus, the literature supports a conclusion of interaction among forage NVAL and quantity in affecting individual animal performance on pasture, but it suggests that the roles of each are quite well defined. [ABSTRACT FROM AUTHOR]

Provides information on a study which used in situ techniques for measuring ruminal degradation of feedstuffs. Theoretical background; Sources of variation with in situ measurements; Implications.

Introduction: Holstein steers ( n  = 32) were used to determine if the ergot analog, bromocriptine decreases muscle protein synthesis through inhibitory action on the mTOR pathway via a direct effect on signal proteins, and if these negative effects can be alleviated with anabolic agents., Methods: Steers were treated with intramuscular administration of bromocriptine (vehicle or 0.1 mg/kg BW) and a subdermal commercial steroidal implant containing trenbolone acetate (TBA) and estradiol 17β (with or without), in a 2×2 factorial design. During the 35 day experiment, intake was restricted to 1.5 times maintenance energy requirement. On days 27 through 32, steers were moved to metabolism stalls for urine collection, and whole-body protein turnover was determined using a single pulse dose of [ 15 N] glycine into the jugular vein on day 28. On day 35, skeletal muscle samples were collected before (basal state) and 60 min after (stimulated state) an i.v. glucose challenge (0.25 g glucose/kg). Blood samples were collected at regular intervals before and after glucose infusion for determination of circulating concentrations of glucose and insulin., Results: Bromocriptine reduced insulin and glucose clearance following the glucose challenge, indicating decreased insulin sensitivity and possible disruption of glucose uptake and metabolism in the skeletal muscle. Conversely, analysis of whole-body protein turnover demonstrated that bromocriptine does not appear to affect protein synthesis or urea excretion. Western immunoblot analysis of skeletal muscle showed that it did not affect abundance of S6K1 or 4E-BP1, so bromocriptine does not appear to inhibit activation of the mTOR pathway or protein synthesis. Estradiol/TBA implant decreased urea excretion and protein turnover but had no effect on protein synthesis, suggesting that steroidal implants promote protein accretion through unchanged rates of synthesis and decreased degradation, even in the presence of bromocriptine, resulting in improved daily gains. Implanted steers likely experienced increased IGF-1 signaling, but downstream activation of mTOR, S6K and 4E-BP1, and thus increased protein synthesis did not occur as expected., Conclusions: Overall, this data suggests that bromocriptine does not have a negative impact on muscle protein synthetic pathways independent of DMI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Ferguson, Loos, Vanzant, Urschel, Klotz and McLeod.)

The objective of the study was to characterize the temporal changes of phosphorylation patterns of mTOR signaling proteins in response to two dietary protein sources in insulin dysregulated (ID, n = 8) and non-ID ( n = 8) horses. Horses were individually housed and fed timothy grass hay and 2 daily concentrate meals so that protein was the first limiting nutrient and the total diet provided 120% of daily DE requirements for maintenance. On sample days, horses randomly received 0.25 g CP/kg BW of a pelleted alfalfa (AP) or commercial protein supplement (PS). Blood samples were collected before and 30, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, and 480 min post feeding and analyzed for plasma glucose, insulin and amino acid (AA) concentrations. G luteus Medius muscle samples were obtained before and 90, 180, and 300 min after feeding and analyzed for relative abundance of phosphorylated mTOR pathway components using western immunoblot analysis. There was no effect of protein source on postprandial glucose and insulin responses ( P ≥ 0.14) but consumption of PS elicited a 2 times larger AUC for essential AA (EAA), greater peak concentrations of EAA and a shorter time to reach peak EAA concentrations compared to AP. Abundance of phosphorylated mTOR ( P = 0.08) and rpS6 ( P = 0.10) tended to be ~1.5-fold greater after consumption of PS at 90 min compared to AP. Dephosphorylation patterns differed between protein sources and was slower for AP compared to PS. ID horses had a 2 times greater ( P = 0.009) AUC and 3 times higher postprandial peak concentrations ( P < 0.0001) for insulin compared to non-ID horses after consumption of both treatment pellets, but EAA responses were similar between groups ( P = 0.53). Insulin status did not affect rpS6 or mTOR phosphorylation after consumption of either protein source ( P ≥ 0.35), but phosphorylated rpS6 abundance was twice as high in ID compared to non-ID horses ( P = 0.007). These results suggest that the consumption of higher quality protein sources may result in greater postprandial activation of the mTOR pathway compared to equal amounts of a forage-based protein source. Moreover, ID does not impair postprandial activation of mTOR and rpS6 proteins in horses following a protein-rich meal., Competing Interests: DD was hired as a consultant by the funder of this project (Versele-Laga, Deinze, Belgium). He also receives a portion of the profits from Cavalor VitAmino. DD is employed by Equivado Consultancy B.V. The funding company did not participate in the analysis or the decision to publish. All authors declare that they had full autonomy and independency in the research and publishing of this work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Loos, McLeod, Vanzant, Stratton, Bohannan, Coleman, van Doorn and Urschel.)

The objectives of the study were to study the effects of the synthetic ergot alkaloid (EA), bromocriptine, on glucose and lipid metabolism in insulin dysregulated (ID, n = 7) and non-ID ( n = 8) mares. Horses were individually housed and fed timothy grass hay and two daily concentrate meals so that the total diet provided 120% of daily DE requirements for maintenance. All horses were given intramuscular bromocriptine injections (0.1 mg/kg BW) every 3 days for 14 days. Before and after 14 days of treatment horses underwent a combined glucose-insulin tolerance test (CGIT) to assess insulin sensitivity and a feed challenge (1 g starch/kg BW from whole oats) to evaluate postprandial glycemic and insulinemic responses. ID horses had higher basal plasma concentrations of insulin ( P = 0.01) and triglycerides ( P = 0.02), and lower concentrations of adiponectin ( P = 0.05) compared with non-ID horses. The CGIT response curve showed that ID horses had slower glucose clearance rates ( P = 0.02) resulting in a longer time in positive phase ( P = 0.03) and had higher insulin concentrations at 75 min ( P = 0.0002) compared with non-ID horses. Glucose ( P = 0.02) and insulin ( P = 0.04) responses to the feeding challenge were lower in non-ID compared to ID horses. Regardless of insulin status, bromocriptine administration increased hay intake ( P = 0.03) and decreased grain ( P < 0.0001) and total DE ( P = 0.0002) intake. Bromocriptine treatment decreased plasma prolactin ( P = 0.0002) and cholesterol ( P = 0.10) and increased ( P = 0.02) adiponectin concentrations in all horses. Moreover, in both groups of horses, bromocriptine decreased glucose clearance rates ( P = 0.02), increased time in positive phase ( P = 0.04) of the CGIT and increased insulin concentrations at 75 min ( P = 0.001). The postprandial glycemic ( P = 0.01) and insulinemic ( P = 0.001) response following the oats meal was lower after bromocriptine treatment in all horses. In conclusion, in contrast to data in humans and rodents, bromocriptine treatment reduced insulin sensitivity in all horses, regardless of their insulin status. These results indicate that the physiological effects of EA might be different in horses compared to other species. Moreover, because bromocriptine shares a high degree of homology with natural EA, further investigation is warranted in horses grazing endophyte-infected grasses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Loos, Urschel, Vanzant, Oberhaus, Bohannan, Klotz and McLeod.)

Endophyte-infected fescue is a major cool season forage used for livestock production in the United States and through other areas of the world. A unique aspect of this forage resource is the symbiotic relationship with an endophytic fungus ( Epichloë coenophiala ) that has detrimental impact on herbivores due to toxic ergot alkaloids. Research over the past 50 years has unveiled details regarding this symbiotic relationship. This review focuses on the origin of tall fescue in the United States and the consequences of its wide-spread utilization as a livestock forage, along with the discovery and toxicodynamics of ergot alkaloids produced by E. coenophiala . The majority of past ergot alkaloid research has focused on observing phenotypic changes that occur in livestock affected by ergot alkaloids, but recent investigation of the metabolome, transcriptome, and proteome have shown that fescue toxicity-related illnesses are much more complex than previous research suggests., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ferguson, Vanzant and McLeod.)

Growing public interest in the use of cannabidiol (CBD) for companion animals has amplified the need to elucidate potential impacts. The purpose of this investigation was to determine the influence of CBD on the daily activity of adult dogs. Twenty-four dogs (18.0 ± 3.4 kg, 9 months-4 years old) of various mixed breeds were utilized in a randomized complete block design with treatments targeted at 0 and 2.5 mg (LOW) and at 5.0 mg (HIGH) CBD/kg body weight (BW) per day split between two treats administered after twice-daily exercise (0700-0900 and 1,700-1,900 h). Four hours each day [1,000-1,200 h (a.m.) and 1,330-1,530 h (p.m.)] were designated as times when no people entered the kennels, with 2 h designated as Quiet time and the other 2 h as Music time, when calming music played over speakers. Quiet and Music sessions were randomly allotted to daily a.m. or p.m. times. Activity monitors were fitted to dogs' collars for continuous collection of activity data. Data were collected over a 14-day baseline period to establish the activity patterns and block dogs by activity level (high or low) before randomly assigning dogs within each block to treatments. After 7 days of treatment acclimation, activity data were collected for 14 days. Data were examined for differences using the MIXED procedure in SAS including effects of treatment, day, session (Quiet or Music), time of day (a.m. or p.m.), and accompanying interactions. CBD (LOW and HIGH) did not alter the total daily activity points ( P = 0.985) or activity duration ( P = 0.882). CBD tended ( P = 0.071) to reduce total daily scratching compared with the control. Dogs were more active in p.m. sessions than in a.m. sessions ( P < 0.001). During the p.m. session, dogs receiving HIGH tended ( P = 0.091) to be less active than the control (CON). During the a.m. and p.m. sessions, CBD reduced scratching compared with CON ( P = 0.030). CBD did not affect the activity duration during exercise periods ( P = 0.143). These results indicate that, when supplemented with up to 4.5 mg CBD/kg BW/day, CBD does not impact the daily activity of adult dogs, but may exert an antipruritic effect., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Morris, Kitts-Morgan, Spangler, Gebert, Vanzant, McLeod and Harmon.)

This experiment was conducted to determine the effects of slow release urea (SRU) and its interaction with crude protein (CP) level in the diet on N metabolism in Holstein steers. Eight rumen-cannulated Holstein steers (body weight 265 ± 18 kg) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial treatment structure. Treatment factors were the CP level in the diet, 10.9% versus 12.1% CP, and the non-protein nitrogen source used, urea versus SRU. Total collection of urine and faeces for 7 days allowed the estimation of N retention and diet digestibility. In addition, blood and rumen sampling allowed estimation of rumen fermentation and blood N profiles. Decreasing CP intake from 12.1% to 10.9% reduced urinary N output, but also reduced diet digestibility and N retention. When compared to urea, SRU did not alter N retention, but reduced ruminal ammonia and plasma urea concentrations. Although SRU did not improve N retention at either CP level, rumen ammonia and plasma urea concentrations were reduced, which may indicate that SRU may carry a lower risk for toxicity when compared to urea when fed at higher dietary concentrations.