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Supplementing trace minerals is common in managing bovine respiratory disease (BRD) in post-weaned cattle; however, its influence on host immunity and metabolism in high-risk cattle remains unclear. We aimed to assess the impact of three supplementation programs on liver and serum trace element concentrations and blood gene expression. Fifty-six high-risk beef steers were randomly assigned to one of three groups over 60 days: (1) sulfate-sourced Cu, Co, Mn, and Zn (INR), (2) amino acid-complexed Cu, Mn, Co, and Zn (AAC), or (3) AAC plus trace mineral and vitamin drench (COMBO). Serum and liver biopsies for Cu, Co, Mn, and Zn at d0, d28, and d60 were analyzed from cattle free of BRD (n = 9 INR; n = 6 AAC; n = 10 COMBO). Differences and correlations of mineral concentrations were analyzed via generalized linear mixed models and Spearman's rank coefficients, respectively ( p < 0.05). Whole blood RNA samples from healthy cattle (n = 4 INR; n = 4 AAC; n = 4 COMBO) at d0, d13, d28, d45, and d60 were sequenced and analyzed for differentially expressed genes (DEGs) via glmmSeq (FDR < 0.05), edgeR (FDR < 0.10), and Trendy ( p < 0.10). Serum and liver Cu and Co concentrations increased over time in all groups, with higher liver Cu in COMBO (487.985 μg/g) versus AAC (392.043 μg/g) at d60 ( p = 0.013). Serum and liver Cu concentrations (ρ = 0.579, p = 6.59 × 10 -8 ) and serum and liver Co concentrations (ρ = 0.466, p = 2.80 × 10 -5 ) were linearly correlated. Minimal gene expression differences were found between AAC versus COMBO (n = 2 DEGs) and INR versus COMBO (n = 0 DEGs) over time. AAC versus INR revealed 107 DEGs (d13-d60) with increased traits in AAC including metabolism of carbohydrates/fat-soluble vitamins, antigen presentation, ATPase activity, and B- and T-cell activation, while osteoclast differentiation and neutrophil degranulation decreased in AAC compared to INR. Our study identifies gene expression differences in high-risk cattle fed inorganic or amino acid-complexed mineral supplements, revealing adaptive immune and metabolic mechanisms that may be improved by organically sourced supplementation.

Nutritional approaches to optimize cattle health and performance during the receiving period are warranted. This experiment evaluated the impacts of supplementing organic complexed Cu, Co, Mn, and Zn on productive and health responses of high-risk beef cattle during a 60-day backgrounding phase. Crossbred steers (120) were purchased at auction and transported to the experimental facility, where BW was recorded (day-1; initial shrunk BW = 227.7 ± 1.3 kg). On day 0, steers were ranked by BW and allocated to one of eight groups and housed in drylot pens equipped with GrowSafe automated feeding systems (Model 8000; two bunks/pen). Groups were randomly assigned to receive a total mixed ration containing: (1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 40); (2) organic complexed sources of the same minerals (AAC; Zinpro Availa 4 based on a metal:amino acid complex ratio of 1:1 for Zn, Cu, and Mn in addition to cobalt glucoheptonate; Zinpro Corp., Eden Prairie, MN; n = 40); or (3) AAC and an organic complexed trace mineral drench (APF; 30 mL/hd; Zinpro ProFusion, Zinpro Corp.) on day 0 and with morbidity treatment (n = 40). Diets provided the same daily amount of all nutrients and minerals based on 7 g/steer daily of Zinpro Availa 4. Steers were assessed for bovine respiratory disease (BRD) signs daily. Liver biopsies were performed on days 0, 28 and 60. Blood samples were collected on days 0, 2, 6, 10, 13, 21, 28 and 45. No treatment differences were detected (P ≥ 0.23) for feed intake, final BW, average daily gain, or BRD incidence. Mean liver Co concentrations were greater (P = 0.02) in AAC and APF compared to INR steers. Mean liver Cu was greater (P = 0.02) in APF compared to AAC steers. Liver Zn tended to be greater (P = 0.10) on day 28 but less (P = 0.05) on day 60 for INR compared to AAC and APF steers. Plasma cortisol was lowest (P = 0.05) for AAC steers on day 6, whereas AAC steers tended to have greater (P = 0.09) plasma cortisol on day 13 compared with APF. Plasma haptoglobin tended to be greater (P ≤ 0.10) for INR steers on days 28 and 45 compared to AAC and APF. While supplementing cattle with AAC or INR results in similar animal performance and clinical disease, AAC and APF reduce stress and acute phase protein responses., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

This experiment evaluated growth, physiological responses, and puberty attainment in beef heifers reared in drylots with a high stocking density, and provided or not with a moderate exercise regimen. A total of 180 heifers (75% Angus × 25% Brahman) were used in this experiment replicated over 2 yr. Each year, 90 heifers were ranked by age (264 ± 1 d) and body weight (BW on day -3; 200 ± 2 kg) on day 0, and assigned to a) one of six drylot pens (10 × 14 m pens; 10 heifers per pen) with a stocking density of 14 m2/heifer (DENS), or b) one of three pastures (2-ha pastures; 10 heifers per pasture) with a stocking density of 2,000 m2/heifer (CON). Beginning on day 15, three DENS pens were given access to an exercise area (DENS-EX) 3 times/wk (1 h). Negligible forage was available for CON, whereas heifers from all treatments received the same limit-fed diet (~13 kg/heifer daily). Shrunk BW was recorded after 16 h of feed and water withdrawal on days -3 and 225 to calculate BW gain. Temperament was evaluated on days 0, 128, and 224. Heifers were fitted with a pedometer behind their shoulder on day 0 to record physical activity. Pedometer results and blood samples were collected weekly for progesterone analysis. Hair samples from the tail switch were collected every 28 d. Data were analyzed with pen or pasture as an experimental unit, via ANOVA using the MIXED or GLIMMIX procedures of SAS (SAS Inst. Inc., Cary, NC). Heifers from CON had more (P < 0.01) steps per week compared with DENS and DENS-EX (23,973, 6,706, and 12,354 steps/wk, respectively; SEM = 1,247), and DENS-EX heifers had more (P < 0.01) steps per week compared with DENS. No treatment effects (P ≥ 0.91) were detected for heifer BW gain (~0.820 kg/d). Hair cortisol concentrations were greater (P ≤ 0.05) in DENS and DENS-EX compared with CON beginning on day 56. Exit velocity and temperament score were greater (P ≤ 0.05) in DENS compared with DENS-EX and CON on day 224. Puberty attainment was delayed (treatment × day; P < 0.01) in DENS compared with DENS-EX and CON. A greater (P ≤ 0.05) proportion of CON were pubertal by day 105 compared with DENS and DENS-EX (30.0%, 11.6%, and 15.0%, respectively; SEM = 6.5), while a greater (P < 0.05) proportion of CON and DENS-EX were pubertal by day 154 compared to DENS (61.7%, 66.7%, and 43.3%, respectively; SEM = 6.5). Rearing replacement heifers in drylots with high stocking density has detrimental effects on their puberty attainment, and the moderate exercise regimen partially alleviated this negative outcome., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

This experiment evaluated the performance, health, and physiological responses of high-risk steers receiving a Bacillus-based probiotic during a 90-d grazing period. A total of 240 Angus-influenced steers were used in this experiment that was replicated over 2 yr (120 steers/year). Each year, steers were obtained from an auction yard and transported to the experimental facility (120 km). Steer body weight (BW) was recorded at arrival (day -1), and this value was averaged with BW recorded on day 0 to represent the initial BW (236.6 ± 1.5 kg). On day 0, steers were ranked by BW and allocated to 1 of 12 pastures with stockpiled native grass (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers' grains at 1% of BW containing either: 1) Bacillus subtilis + B. licheniformis probiotic (BOV; 2 g/steer daily of Bovacillus; Novonesis, Horsholm, Denmark) or 2) no feed additive (CON). Cattle received treatments from days 0 to 90, in addition to free-choice access to water and mineral + vitamin mix without ionophore. Steers were assessed for bovine respiratory disease (BRD) signs daily. Blood samples were collected and full BW was recorded on days 0, 14, 28, 56, and 90. Shrunk BW was recorded on day 91 after 16 h of feed and water restriction, and a 4% pencil shrink was used to calculate the final BW. Average daily gain (ADG) was calculated based on initial and final BW. No treatment effects were detected (P ≥ 0.73) for steer final BW and ADG. A treatment × day interaction was detected (P ≤ 0.05) for plasma haptoglobin concentration, which was greater for CON steers on days 14 and 28 (P ≤ 0.02). Incidence of BRD signs did not differ (P = 0.97) between treatments (51.7% and 51.3% for BOV and CON, respectively; SEM = 7.70). However, steer mortality + removals for health complications were greater (P = 0.01) in CON compared to BOV (0.00% vs. 5.04%, respectively; SEM = 1.41). Supplementing BOV improved (P ≤ 0.04) total pasture-based liveweight change (643 vs. 502 kg/pasture, respectively; SEM = 45) and final pasture-based total liveweight (3,007 vs. 2,869 kg/pasture, respectively; SEM = 46). Collectively, supplementation with a probiotic based on B. subtilis and B. licheniformis to high-risk stocker cattle did not alleviate the incidence of BRD signs nor improved ADG, but decreased acute-phase protein response, reduced steer mortality + removal, and increased pasture-based productivity during a 90-d grazing period., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Presynchronization was evaluated as a method to improve estrus response before fixed-time AI (FTAI). The objective was to compare FTAI results in beef cows from two different presynchronization approaches. Blood samples were collected on Day -14 (Day 0 = CIDR removal) to determine progesterone concentration (≥1 ng/mL = high, <1 ng/mL = low). In a subset (n = 1289), an additional blood sample was collected between Day -21 and -29 to determine cyclicity (if both the Day -14 and Day -21 to -29 samples were classified as low progesterone cows were classified as noncycling). Cows (n = 1388) from 30 herds were grouped by days postpartum (DPP) and age, and randomly assigned to either of two protocols. Cows assigned to the PG 6-day CIDR & FTAI protocol (PG6d) received prostaglandin F 2α (PG) on Day -9, CIDR insertion and GnRH on Day -6, and CIDR removal and PG on Day 0. Cows assigned to the 7&7 Synch protocol (7&7) were administered PG and CIDR insertion on Day -14, GnRH on Day -7, and CIDR removal and PG on Day 0. For both protocols, FTAI occurred concurrently with GnRH 66 h after second PG. Pregnancy was determined by transrectal ultrasonography 30-40 d after FTAI. The GLIMMIX procedure of SAS was used to detect differences in estrus response and pregnancy success with herd as a random variable. Estrus response (0-66 h) was analyzed with two models, one included cyclicity and another replaced cyclicity with progesterone concentration at Day -14. In both models, cows assigned to the 7&7 protocol had greater (P < 0.01) estrus response than cows assigned to the PG6d protocol. The model including cyclicity, estrus response was impacted by the cyclicity by DPP interaction (P = 0.03), cyclicity by protocol interaction (P = 0.04), and the tendency of BCS by protocol interaction (P = 0.08). In the estrus response model that included progesterone concentration at Day -14, significant variables included the protocol by progesterone concentration at Day -14 (P = 0.01), and BCS (P < 0.01), while DPP (P = 0.08) and progesterone concentration at Day -14 (P = 0.07) were tendencies. Pregnancy success was influenced by estrual status (P < 0.01), body condition score (P = 0.04), and cycling status (P = 0.02), but was not influenced by protocol (P = 0.75; PG6d = 38 ± 5% and 7&7 = 37 ± 5%). In conclusion, effectiveness of presynchronization method depended on a cows' physiological status, and the 7&7 protocol increased estrus response compared with PG6d, but there was no difference in pregnancy success., Competing Interests: Declaration of competing interest There are no known competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)