Jennifer L. Hurlbert

Angus-based heifers (F0; n = 72; 14 to 15 mo; initial body weight [BW] = 380.4 ± 50.56 kg) were ranked by BW, bred via artificial insemination (AI) with female-sexed semen, and assigned to receive a basal diet (CON; n = 36) or the basal diet plus a vitamin and mineral supplement (VTM; n = 36) with the total mixed ration. Treatments were applied from breeding through calving, after which cow–calf pairs (n = 14 CON; n = 17 VTM) received a common diet. A subset of F1 heifers (n = 7 CON; n = 9 VTM) were bred via AI with female-sexed semen and evaluated from breeding through d 250 of gestation when pregnant heifers were slaughtered. Nutrient balance and energy metabolism were measured each trimester via apparent total tract digestibility and indirect calorimetry. Blood samples were collected each trimester and at harvest for hormone/metabolite analysis. Data were analyzed using the MIXED procedure of SAS with repeated measures where appropriate, with treatment, time, and interaction included as fixed effects and animal as the experimental unit. In F1 heifers, digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber, and N was not influenced by treatment (P ≥ 0.21) but decreased (P ≤ 0.03) as gestation advanced. Fecal energy (FE) losses, heat production (HP) as a percentage of gross energy intake, and retained energy (RE) were not affected by treatment (P ≥ 0.52); however, FE and HP increased (P ≤ 0.03) while RE decreased (P = 0.01) with advancing gestation. Circulating insulin concentration was greater (P < 0.01) in VTM heifers, whereas glucose decreased (P < 0.01) and non-esterified fatty acids and blood urea nitrogen increased (P ≤ 0.01) as gestation progressed. Body weight was greater (P < 0.01) in VTM heifers and at slaughter, VTM heifers tended (P ≤ 0.10) to have heavier carcasses and greater ribeye area than CON. The F1 CON heifers had heavier spleens relative to BW (P = 0.04) whereas other organs did not differ (P ≥ 0.17). In F2 fetuses, CON tended to have heavier reproductive tracts and spleens (P ≤ 0.10) with no other differences in organ weights (P ≥ 0.13), whereas VTM fetuses had greater (P = 0.01) blood glucose concentration. These results indicate that prenatal micronutrient supplementation programs growth and metabolic function across generations, with minimal effects on organ mass. Advancing gestation reduced efficiency of energy and nitrogen use, reflecting nutrient partitioning shifts supporting fetal growth.

We investigated gene regulatory relationships in the neonatal liver to identify potential mechanisms by which maternal vitamin and mineral supplementation during gestation influences developmental programming in heifer calves. Liver transcriptomes were profiled by RNA-Seq in calves collected 30 h after birth from dams fed either a basal diet (CON; n = 6) or the basal diet plus a vitamin and mineral premix (VTM; n = 6; 113 g·heifer⁻¹·d⁻¹), starting 60 days pre-breeding and continuing through gestation. Using DESeq2, we identified 630 DEGs between treatment groups (p ≤ 0.05 and |log2FC| ≥ 0.5). Over-represented pathways included oxidative phosphorylation, AMPK, PI3K/Akt, and FoxO, key regulators of energy homeostasis. We also identified 58 transcription factors (TFs) and 435 differentially connected genes (p ≤ 0.05), suggesting maternal diet induced a regulatory rewiring of TFs and histone deacetylating genes. Gene set enrichment analysis revealed genes positively ranked, such as LRAT and LMBRD1, underlying the vitamin digestion and absorption pathway, indicating coordinated upregulation in the VTM group. Conversely, 23 DEGs associated with the OXPHOS KEGG pathway were downregulated in the VTM calves. Further research should explore whether these transcriptional changes are linked to epigenetic modifications established at birth, persist throughout postnatal development, and potentially contribute to multigenerational inheritance.

Two experiments assessed the effects of providing a vitamin and mineral supplement to gestating beef heifers on concentrations of immunoglobulins (Ig) in colostrum and calf serum 24 h after feeding maternal colostrum (Exp. 1) or a colostrum-replacement product (Exp. 2). Angus-based heifers (n = 31, Exp. 1; n = 14, Exp. 2) were fed a basal diet (CON) or were fed a basal diet plus a vitamin and mineral supplement (VTM) from breeding (Exp. 1) or 60 d pre-breeding (Exp. 2) through calving. Colostrum was collected at calving, and serum was collected from calves 24 h after colostrum consumption to evaluate passive transfer. Serum was collected from calves in Exp. 1 to determine serum titers in response to vaccination at birth, pasture turn out, weaning, and 14 d after vaccination. Concentrations of IgG, IgM, or IgA in colostrum or in calf serum at 24 h were not impacted by dam treatment (p ≥ 0.21); however, concentrations of Ig in calf serum at 24 h were greater (p ≤ 0.01) in calves receiving maternal colostrum than those receiving a colostrum replacer. Calves born to VTM heifers had greater antibody titers at birth, pasture turn out, and weaning for infectious bovine rhinotracheitis (IBR), bovine viral diarrhea virus type 2 (BVD-2), and bovine respiratory syncytial virus (BRSV), respectively. Our results suggest that the programming of immune function in calves via prenatal nutrition appears to extend postnatally in CON and VTM offspring.

The effect of vitamins and minerals supplementation (VTM) and/or two rates of body weight gain (GAIN) on bovine placental vascular development and angiogenic factors gene expression were evaluated in two experiments: In Exp. 1, crossbred Angus heifers (n = 34) were assigned to VTM/NoVTM treatments at least 71 days before breeding to allow changes in the mineral status. At breeding, through artificial insemination (AI), heifers were assigned to low-gain (LG) 0.28 kg/d or moderate-gain (MG) 0.79 kg/d treatments, resulting in NoVTM-LG (Control; n = 8), NoVTM-MG (n = 8), VTM-LG (n = 9), and VTM-MG (n = 9) until day 83 of gestation; In Exp. 2, crossbred angus heifers (n = 28), were assigned to control (CON; n = 12), receiving a basal total mixed ration (TMR) or TMR + VTM (VTM; n = 16) from breeding until parturition. Placentomes from Exp. 1 and cotyledons (COT) from Exp. 2 were evaluated by immunohistochemistry for COT vascular density area. COTs from Exp. 1 were evaluated for angiogenic factor (ANGPT-1, ANGPT-2, eNOS2, eNOS3, FLT1, KDR, TEK, VEGFA) gene expression. In Exp. 1, COT vascularity was not affected by the interaction of VTM and GAIN (p = 0.67) or the main effects of VTM (p = 0.50) and GAIN (p = 0.55). Likewise, angiogenic factors were not differentially expressed between treatments (p < 0.05). In Exp. 2, COT vascularity was greater in VTM vs. CON (p = 0.07). In conclusion, there is a suggested later-stage influence of vitamin and mineral supplementation on placental vascularity, emphasizing the importance of supplementation beyond early pregnancy.

To examine the effects of feeding a vitamin and mineral supplement to beef heifers throughout gestation on mineral status and hormone/endocrine profiles in the dam and calf, and morphometric characteristics and organ mass of the calf at 30 h after birth, Angus-based heifers (n = 72, 14 to 15 months of age, initial body weight [BW] = 380.4 ± 50.56 kg) were estrus synchronized and artificially inseminated (AI) with female-sexed semen. Heifers were blocked by BW and randomly assigned to receive either a basal diet (CON; n = 36) or a basal diet plus a vitamin and mineral supplement (VTM; n = 36) via an individual feeding system beginning at breeding, with both diets targeting BW gains of 0.45 kg heifer^-1•d^-1. Heifers not pregnant after first AI (CON, n = 19; VTM, n = 18) were re-bred via AI 60 d after treatment initiation, and heifers gestating female fetuses (CON, n = 7; VTM, n = 7) received treatments throughout gestation and were experimental units for this study. Calves were separated from their dams and fed colostrum replacer within 2 h of birth and euthanized 30 h after the first feeding. Calf morphometrics were recorded, and tissues were weighed and sampled. Serum from the dam at calving and serum, liver, and muscle from the calf at 30 h were analyzed for concentrations of minerals. Serum from the dam and calf were analyzed for concentrations of leptin, vitamins A, D, and E, cortisol, growth hormone, and insulin-like growth factor 1. All response variables were analyzed using the MIXED procedure of SAS. Calf body morphometrics and BW of the dam at calving (P ≥ 0.32), calf organ weights (P ≥ 0.21), and calf ovarian follicle counts (P ≥ 0.13) were not affected by maternal treatment. Concentrations of Se and Co in calf serum and Se in calf liver were increased (P ≤ 0.02) in VTM. Serum concentrations of Co and vitamin A in the dam were greater (P ≤ 0.01) in supplemented compared with non-supplemented dams, and serum concentrations of vitamin D were greater (P ≤ 0.0003) in supplemented dams and calves compared with the non-supplemented cohort. Maternal supplementation supported vitamin and mineral status in the neonate, yet had no discernable impact on BW, organ mass, or circulating hormones/metabolites in the calf. Evaluating offspring at later postnatal time points is warranted to determine if prenatal vitamin and mineral supplementation affects performance, health, metabolism, and efficiency of energy utilization in key metabolic tissues in the calf.

Two experiments were conducted to evaluate the impacts of feeding a vitamin/mineral supplement to beef heifers throughout gestation on concentrations of immunoglobulin (Ig) in colostrum and in calf serum 24 h after consumption of maternal colostrum (Exp. 1) or a colostrum replacement product (Exp. 2). Angus-based beef heifers [n = 72, initial body weight (BW) = 380.4 ± 50.56 kg] were managed in an individual feeding system and randomly assigned to a basal diet targeting gain of 0.45 kg·heifer^-1·d^-1 (CON; n = 36) or the basal diet plus 113 g·heifer^-1·d^-1 of a vitamin/mineral supplement (VTM; n = 36). For Exp. 1 treatments began at the time of artificial insemination (AI) to sexed semen, and heifers becoming pregnant after first service AI (CON, n = 14; VTM, n = 17) continued treatments throughout gestation. At calving, heifer calves were allowed to nurse their dams and remained alongside their dams until weaning. For Exp 2. non-pregnant heifers were rebred 60 d after initial dietary treatments began and continued treatments throughout gestation, with resultant heifer calves (CON, n = 7; VTM, n = 7) being removed from their dams at birth and receiving 1.5 L of colostrum replacer containing 150 g globulin protein via an esophageal feeder, followed every 12 h by 1.9 L of milk replacer. In both experiments samples of colostrum were collected after completely milking the rear-right quarter of the udder. Blood samples were collected from calves before (within 2 h of birth) and 24 h after colostrum consumption. Concentrations of IgG, IgM, and IgA were quantified in colostrum and serum via bovine radial immunodiffusion plates. Data for both experiments were analyzed for the effect of treatment using the MIXED procedure in SAS, with additional analysis of data from Exp. 1 using the CORR procedure to determine correlations among dam colostrum and calf serum Ig concentrations at 24 h. In both experiments, maternal treatment did not affect (P ≥ 0.21) concentrations of IgG, IgM, or IgA in colostrum at calving or in calf serum at 24 h. All calves from both experiments had undetectable concentrations of these respective immunoglobulins at birth. Concentrations of IgG at 24 h in calves that received maternal colostrum were 2,595.8 ± 535.38 mg/dL (Exp. 1), whereas those that received colostrum replacer were 1,610.6 ± 335.09 mg/dL (Exp. 2). Concentrations of IgG, IgM, and IgA were positively correlated (r ≥ 0.34; P ≤ 0.05) with concentrations of calf serum IgG, IgM, and IgA at 24 h after suckling. Our results suggest that maternal vitamin/mineral supplementation throughout gestation did not impact Ig concentrations in colostrum or the resultant serum Ig concentrations in calves either 24 h after suckling or after delivery of a commercial colostrum replacer.

Our objectives were to evaluate the impacts of providing vitamin and mineral (VTM) supplements to cow-calf pairs during the summer grazing period on cow and calf performance and liver concentrations of minerals. During a two-year period, 727 crossbred cows and their calves (initial cow BW = 601.7 ± 48.1 kg; calf BW = 87.8 ± 5.0 kg; n = 381 in year 1, n = 346 in year 2) from the Central Grasslands Research Extension Center (Streeter, N.D.) were blocked by parity (young [parity 1 to 3], and old [parity 4+]) and randomly assigned to pastures at the beginning of the grazing season (16 in year 1 and 14 in year 2). Pastures were assigned to receive a free-choice VTM supplement (SUPP) or no VTM supplement (CON) from pasture turnout to pasture removal (158 and 156 days in year 1 and 2, respectively). Consecutive day weights were taken from cows and calves at pasture turnout and removal and liver biopsies were collected from a subset of cows at both timepoints and from calves at weaning. Cows were bred via AI 37 to 41 d after pasture turnout and by natural service cleanup bulls for a 70 to 80 d breeding season. Calving and weaning data were collected from the calf conceived and gestated during treatments. Data were analyzed for the effect of VTM treatment (SUPP vs. CON), block of parity, and their interaction using the GLM procedure of SAS with pasture as the experimental unit. Year was considered a random effect in the final analysis. Cow pregnancy success was evaluated using the GLIMMIX procedure in SAS with model terms of VTM treatment, parity, and their interaction with year as a random effect. In year 2, cows in differing days postpartum (DPP) groups at pasture turnout (66.1, 48.8, and 34.5 ± 1.04 DPP for EARLY, MID, and LATE groups, respectively) were selected for liver biopsies with cow as the experimental unit. Cow and calf BW and BW change were not impacted (P ≥ 0.20) by VTM access. Pregnancy rate to AI, overall pregnancy rate, gestating calf birth BW and calving distribution were not affected (P ≥ 0.11) by treatment. Liver concentrations of Se, Cu, and Co were greater (P ≤ 0.002) at pasture removal and weaning for cows and suckling calves that had access to VTM. Cows considered EARLY calving had greater (P = 0.05) concentrations of liver Se compared with LATE calving cows. Although VTM supplementation enhanced concentrations of key minerals in the liver of cow-calf pairs, reproductive and growth performance was not affected.

Objectives were to evaluate impacts of divergent planes of nutrition on body weight (BW), hormone and metabolite concentrations, and semen characteristics in rams. Mature Rambouillet rams (n = 24, BW = 83.1 ± 2.64 kg) were individually housed and randomly assigned to positive (POS; n = 8), maintenance (MAINT; n = 8), or negative (NEG; n = 8) planes of nutrition for 84 d. Rams were fed a common diet with feed allocations adjusted weekly based on BW to achieve targeted weight gain or loss (approximately 12% initial BW). On d 0, 28, 56, and 84, body condition scores (BCS) and scrotal circumference (SC) were recorded, and blood and semen were collected. Blood was analyzed for triiodothyronine (T3), thyroxine (T4), testosterone, insulin-like growth factor-1 (IGF-1), glucose, and non-esterified fatty acids (NEFA). Semen was collected via electroejaculation and analyzed by Computer Assisted Semen Analysis. Data were analyzed with the GLM or MIXED procedure of SAS, with ram as experimental unit and significance determined at P < 0.05. By design, BW was influenced by a treatment × day interaction (P < 0.0001), and daily weight change was greater (P < 0.0001) for POS (0.11 ± 0.011 kg) than MAINT (0.01 ± 0.011 kg), which was greater (P < 0.0001) than NEG (-0.12 ± 0.011 kg). Consequently, BCS, and SC were greater for POS than NEG as evidenced by a treatment × day interaction (P < 0.0001). Concentrations of T3, IGF-1, and NEFA were increased in POS compared with NEG and MAINT by day 84 (P ≤ 0.03), whereas T4, testosterone, and glucose remained unaffected (P ≤ 0.39). No differences were observed among treatments for semen volume/concentration, motility, or morphology (P ≤ 0.49). Collectively, BW, hormone, and metabolites differed among treatments, indicating a potential for epigenetic alterations which could influence offspring outcomes.

Two experiments were conducted to evaluate effects of vitamin and mineral supplementation during gestation on milk yield and composition at a single point in time, or via daily milk production during early lactation in beef heifers. Forty-one Angus-based heifers received either a basal ration (CON) or the basal diet plus vitamin mineral supplementation (VTM, 113 g•heifer^-1•d^-1) from breeding until parturition. For experiment 1, 29 heifers (12 CON and 17 VTM) were managed as one pasture group after parturition. Using a portable milking machine, heifers were milked at d 56 postpartum between 7 and 10.5 hours after calf removal. For experiment 2, 12 heifers (6 CON and 6 VTM) were acclimated to a free stall barn and milked twice daily for 78 d following parturition. Milk yield was recorded at each milking and samples were collected at d 32, 58, and 78 for component analysis. Data were analyzed using the GLM procedure of SAS. For grazing heifers, milk yield and components (P ≤ 0.91) did not differ between treatments, with mean yield of 9.95 ± 0.34 kg/d, 4.09 ± 0.11% fat and 2.82 ± 0.04% protein. Twice daily milking data (8.19 ± 0.08 kg/d mean yield with 3.43 ± 0.14 % fat and 3.17 ± 0.03 % protein) revealed that after d 7 milk yield remained similar for the rest of the evaluation period (P ≥ 0.12); however, protein was greater (P = 0.02) at d 58 (3.26 ± 0.05%) compared with d 32 (3.10 ± 0.05%) and urea was reduced (P < 0.0001) at d 78 compared with either d 32 or 58 (11.24 ± 0.55 vs. 18.84 ± 0.55 and 19.10 ± 0.55 mg/dL, respectively). Overall, the successful management of these beef heifers in a dairy facility lays the platform for future work that will establish energy requirements during early lactation for primiparous beef cows.