Vitamin and Mineral Supplementation and Rate of Gain in Beef Heifers I: Effects on Dam Hormonal and Metabolic Status, Fetal Tissue and Organ Mass, and Concentration of Glucose and Fructose in Fetal Fluids at d 83 of Gestation

A review of emerging technologies, nutritional practices, and management strategies to improve intramuscular fat composition in beef cattle

The flavour, tenderness and juiciness of the beef are all impacted by the composition of the intramuscular fat (IMF), which is a key determinant of beef quality. Thus, enhancing the IMF composition of beef cattle has become a major area of research. Consequently, the aim of this paper was to provide insight and synthesis into the emerging technologies, nutritional practices and management strategies to improve IMF composition in beef cattle. This review paper examined the current knowledge of management techniques and nutritional approaches relevant to cattle farming in the beef industry. It includes a thorough investigation of animal handling, weaning age, castration, breed selection, sex determination, environmental factors, grazing methods, slaughter weight and age. Additionally, it rigorously explored dietary energy levels and optimization of fatty acid profiles, as well as the use of feed additives and hormone implant techniques with their associated regulations. The paper also delved into emerging technologies that are shaping future beef production, such as genomic selection methods, genome editing techniques, epigenomic analyses, microbiome manipulation strategies, transcriptomic profiling approaches and metabolomics analyses. In conclusion, a holistic approach combining genomic, nutritional and management strategies is imperative for achieving targeted IMF content and ensuring high-quality beef production.

lncRNA-gene network analysis reveals the effects of early maternal nutrition on mineral homeostasis and energy metabolism in the fetal liver transcriptome of beef heifers

Maternal nutrition during pregnancy influences fetal development; however, the regulatory markers of fetal programming across different gestational phases remain underexplored in livestock models. Herein, we investigated the regulatory role of long non-coding RNAs (lncRNAs) on fetal liver gene expression, the impacts of maternal vitamin and mineral supplementation, and the rate of maternal body weight gain during the periconceptual period. To this end, crossbred Angus heifers (n=31) were randomly assigned to a 2×2 factorial design to evaluate the main effects of the rate of weight gain (low gain [LG, avg. daily gain of 0.28 kg/day] vs. moderate gain [MG, avg. daily gain of 0.79 kg/day]) and vitamins and minerals supplementation (VTM vs. NoVTM). On day 83±0.27 of gestation, fetuses were collected for morphometric measurements, and fetal liver was collected for transcriptomic and mineral analyses. The maternal diet significantly affected fetal liver development and mineral reserves. Using an RNA-Seq approach, we identified 320 unique differentially expressed genes (DEGs) across all six comparisons (FDR <0.05). Furthermore, lncRNAs were predicted through the FEELnc pipeline, revealing 99 unique differentially expressed lncRNAs (DELs). The over-represented pathways and biological processes (BPs) were associated with energy metabolism, Wnt signaling, CoA carboxylase activity, and fatty acid metabolism. The DEL-regulated BPs were associated with metal ion transport, pyrimidine metabolism, and classical energy metabolism-related glycolytic, gluconeogenic, and TCA cycle pathways. Our findings suggest that lncRNAs regulate mineral homeostasis- and energy metabolism-related gene networks in the fetal liver in response to early maternal nutrition.

Supplementing vitamins and minerals to beef heifers during gestation: impacts on mineral status in the dam and offspring, and growth and physiological responses of female offspring from birth to puberty

We evaluated the effects of feeding a vitamin and mineral supplement to nulliparous beef heifers throughout gestation on the mineral status of the dam, calf, placenta, and colostrum; offspring growth performance; and physiological responses of offspring raised as replacement heifers. Angus-based heifers (n = 31, initial body weight [BW] = 412.5 ± 53.68 kg) were adapted to an individual feeding system for 14 d, estrus synchronized and bred with female-sexed semen. Heifers were ranked by BW and randomly assigned to receive either a basal diet (CON; n = 14) or the basal diet plus 113 g heifer-1 d-1 of the vitamin and mineral supplement (VTM; n = 17). Targeted BW gains for both treatments was 0.45 kg heifer-1 d-1. Liver biopsies were obtained from dams at breeding, days 84 and 180 of gestation. At calving, liver biopsies were taken from dams and calves; colostrum, placenta, and blood samples were collected; and calf body measurements were recorded. After calving, all cow-calf pairs received a common diet through weaning, and F1 heifer calves were managed similarly after weaning. Offspring growth performance, feeding behavior, blood metabolites, and hormones were evaluated from birth through 15 mo of age. Data were analyzed using the MIXED procedure in SAS with repeated measures where appropriate. Hepatic concentrations of Se decreased in VTM dams (P ≤ 0.05) from day 84 to calving, while concentrations of Cu decreased in VTM and CON (P ≤ 0.05) from day 84 to calving. Calf liver concentrations of Se, Cu, Zn, and Co at birth were greater for VTM than CON (P ≤ 0.05), but calf birth BW and body measurements were not different (P = 0.45). Placental Se, colostrum quantity, total Se, Cu, Zn, and Mn in colostrum were greater (P ≤ 0.04) in VTM dams than CON. Finally, offspring from VTM dams were heavier than CON (P < 0.0001) from weaning through 15 mo of age. These results were coupled with greater (P ≤ 0.04) blood glucose at birth, decreased (P ≤ 0.05) blood urea nitrogen at pasture turn out and weaning, and altered feeding behaviors in VTM offspring compared with CON. Maternal gestational vitamin and mineral supplementation enhanced mineral status in dams and F1 progeny, augmented postnatal offspring growth and blood metabolites. Consequently, in utero vitamin and mineral supplementation may exert programming outcomes on the performance and productivity of females raised as herd replacements and should be considered when developing diets for gestating cows and heifers.

Vitamin and mineral supplementation to beef heifers during gestation: impacts on morphometric measurements of the neonatal calf, vitamin and trace mineral status, blood metabolite and endocrine profiles, and calf organ characteristics at 30 h after birth

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 mo 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 the first AI (CON, n = 19; VTM, n = 18) were rebred 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 nonsupplemented dams, and serum concentrations of vitamin D were greater (P ≤ 0.0003) in supplemented dams and calves compared with the nonsupplemented 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.

One-carbon metabolite supplementation to nutrient-restricted beef heifers affects placental vascularity during early pregnancy

We hypothesized that restricted maternal nutrition and supplementation of one-carbon metabolites (OCM; methionine, folate, choline, and vitamin B12) would affect placental vascular development during early pregnancy. A total of 43 cows were bred, and 32 heifers successfully became pregnant with female calves, leading to the formation of four treatment groups: CON - OCM (n = 8), CON + OCM (n = 7), RES - OCM (n = 9), and RES + OCM (n = 8). The experimental design was a 2 × 2 factorial, with main factors of dietary intake affecting average daily gain: control (CON; 0.6 kg/d ADG) and restricted (RES; -0.23 kg/d ADG); and OCM supplementation (+OCM) in which the heifers were supplemented with rumen-protected methionine (7.4 g/d) and choline (44.4 g/d) and received weekly injections of 320 mg of folate and 20 mg of vitamin B12, or received no supplementation (-OCM; corn carrier and saline injections). Heifers were individually fed and randomly assigned to treatment at breeding (day 0). Placentomes were collected on day 63 of gestation (0.225 of gestation). Fluorescent staining with CD31 and CD34 combined with image analysis was used to determine the vascularity of the placenta. Images were analyzed for capillary area density (CAD) and capillary number density (CND). Areas evaluated included fetal placental cotyledon (COT), maternal placental caruncle (CAR), whole placentome (CAR + COT), intercotyledonary fetal membranes (ICOT, or chorioallantois), intercaruncular endometrium (ICAR), and endometrial glands (EG). Data were analyzed with the GLM procedure of SAS, with heifer as the experimental unit and significance at P ≤ 0.05 and a tendency at P > 0.05 and P < 0.10. Though no gain × OCM interactions existed (P ≥ 0.10), OCM supplementation increased (P = 0.01) CAD of EG, whereas nutrient restriction tended (P < 0.10) to increase CAD of ICOT and CND of COT. Additionally, there was a gain × OCM interaction (P < 0.05) for CAD within the placentome and ICAR, such that RES reduced and supplementation of RES with OCM restored CAD. These results indicate that maternal rate of gain and OCM supplementation affected placental vascularization (capillary area and number density), which could affect placental function and thus the efficiency of nutrient transfer to the fetus during early gestation.

Effects of rate of body weight gain during the first trimester of gestation on beef heifer and offspring performance, concentrations of hormones and metabolites, and response to vaccination

Our study objectives were to evaluate the effects of divergent rates of body weight (BW) gain during early gestation in beef heifers on F0 performance, metabolic and endocrine status, colostrum immunoglobulins, and subsequent F1 calf characteristics, growth performance, concentrations of hormones and metabolites, and response to vaccination. Angus-based heifers (n = 100; BW = 369 ± 2.5 kg) were adapted to individual feeding for 14 d and bred using artificial insemination with female-sexed semen. Heifers were ranked by BW and assigned to either a basal diet targeting 0.28 kg/d gain (low [LG], n = 50) or the basal diet plus an energy/protein supplement targeting 0.79 kg/d gain (moderate gain [MG], n = 50) until day 84 of gestation. Dam BW and blood samples were collected at 6 time points during gestation; body composition was evaluated on days -10 and 84; and fetal measurements were taken on days 42, 63, and 84. At calving (LG, n = 23; MG, n = 23), dam and calf BW were recorded; and colostrum, calf body measurements, and blood samples were collected. Cow-calf pairs were managed on a common diet from calving to weaning, followed by a common postnatal development period for all F1 female offspring. Growth performance, hormone and metabolite profiles, feeding behavior, and reproductive performance were assessed from birth to prebreeding in F1 heifers. Offspring were vaccinated against respiratory disease and bovine viral diarrhea pathogens on days 62.3 ± 4.13 and 220.3 ± 4.13 postcalving. By design, MG dams were heavier (P < 0.0001) than LG on day 84, and the BW advantage persisted until subsequent weaning of F1 calves. Concentrations of serum IGF-1 and glucose were increased throughout gestation (P < 0.001) in MG dams, whereas concentrations of NEFA were decreased (P < 0.001) in LG dams. Calves from MG dams were 2.14 kg heavier (P = 0.03) and had larger chest circumference (P = 0.04) at birth compared with LG cohorts. Heifers from MG dams continued to have greater (P ≤ 0.03) BW gain and feed efficiency during the development period, but no differences were observed (P ≥ 0.13) in body composition, concentrations of hormones and metabolites, feeding behavior, puberty attainment, and response to vaccination in F1 offspring. Hence, early gestation rate of gain impacted BW and concentrations of glucose and IGF-1 throughout gestation in the F0 dam, resulting in altered F1 calf BW and measurements at birth and increased gain and efficiency during the development period.

Whole-body microbiota of newborn calves and their response to prenatal vitamin and mineral supplementation

Early life microbial colonization and factors affecting colonization patterns are gaining interest due to recent developments suggesting that early life microbiome may play a role in Developmental Origins of Health and Disease. In cattle, limited information exists on the early microbial colonization of anatomical sites involved in bovine health beyond the gastrointestinal tract. Here, we investigated 1) the initial microbial colonization of seven different anatomical locations in newborn calves and 2) whether these early life microbial communities and 3) serum cytokine profiles are influenced by prenatal vitamin and mineral (VTM) supplementation. Samples were collected from the hoof, liver, lung, nasal cavity, eye, rumen (tissue and fluid), and vagina of beef calves that were born from dams that either received or did not receive VTM supplementation throughout gestation (n = 7/group). Calves were separated from dams immediately after birth and fed commercial colostrum and milk replacer until euthanasia at 30 h post-initial colostrum feeding. The microbiota of all samples was assessed using 16S rRNA gene sequencing and qPCR. Calf serum was subjected to multiplex quantification of 15 bovine cytokines and chemokines. Our results indicated that the hoof, eye, liver, lung, nasal cavity, and vagina of newborn calves were colonized by site-specific microbiota, whose community structure differed from the ruminal-associated communities (0.64 ≥ R² ≥ 0.12, p ≤ 0.003). The ruminal fluid microbial community was the only one that differed by treatment (p < 0.01). However, differences (p < 0.05) by treatment were detected in microbial richness (vagina); diversity (ruminal tissue, fluid, and eye); composition at the phylum and genus level (ruminal tissue, fluid, and vagina); and in total bacterial abundance (eye and vagina). From serum cytokines evaluated, concentration of chemokine IP-10 was greater (p = 0.02) in VTM calves compared to control calves. Overall, our results suggest that upon birth, the whole-body of newborn calves are colonized by relatively rich, diverse, and site-specific bacterial communities. Noticeable differences were observed in ruminal, vaginal, and ocular microbiota of newborn calves in response to prenatal VTM supplementation. These findings can derive future hypotheses regarding the initial microbial colonization of different body sites, and on maternal micronutrient consumption as a factor that may influence early life microbial colonization.

Dataset of RNA-Seq transcriptome of the fetal liver at day 83 of gestation associated with periconceptual maternal nutrition in beef heifers

Herein, we present a dataset based on the RNA-Seq analysis of liver tissue from bovine female fetuses at day 83 of gestation. The findings were reported in the main article, "Periconceptual maternal nutrition affects fetal liver programming of energy- and lipid-related genes" [1]. These data were generated to investigate the effects of periconceptual maternal vitamin and mineral supplementation and rates of body weight gain on the transcript abundance of genes associated with fetal hepatic metabolism and function. To this end, crossbred Angus beef heifers (n = 35) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial design. The main effects tested were vitamin and mineral supplementation (VTM or NoVTM - at least 71 days pre-breeding to day 83 of gestation) and rate of weight gain (low (LG - 0.28 kg/d) or moderate (MG - 0.79 kg/d) - from breeding to day 83). The fetal liver was collected on day 83 ± 0.27 of gestation. After total RNA isolation and quality control, strand-specific RNA libraries were prepared and sequenced on the Illumina® NovaSeq 6000 platform to generate paired-end 150-bp reads. After read mapping and counting, differential expression analysis was performed with edgeR. We identified 591 unique differentially expressed genes across all six vitamin-gain contrasts (FDR ≤ 0.1). To our knowledge, this is the first dataset investigating the fetal liver transcriptome in response to periconceptual maternal vitamin and mineral supplementation and/or the rate of weight gain. The data described in this article provides genes and molecular pathways differentially programming liver development and function.

Maternal Mineral Nutrition Regulates Fetal Genomic Programming in Cattle: A Review

Maternal mineral nutrition during the critical phases of fetal development may leave lifetime impacts on the productivity of an individual. Most research within the developmental origins of the health and disease (DOHaD) field is focused on the role of macronutrients in the genome function and programming of the developing fetus. On the other hand, there is a paucity of knowledge about the role of micronutrients and, specifically, minerals in regulating the epigenome of livestock species, especially cattle. Therefore, this review will address the effects of the maternal dietary mineral supply on the fetal developmental programming from the embryonic to the postnatal phases in cattle. To this end, we will draw a parallel between findings from our cattle model research with data from model animals, cell lines, and other livestock species. The coordinated role and function of different mineral elements in feto-maternal genomic regulation underlies the establishment of pregnancy and organogenesis and, ultimately, affects the development and functioning of metabolically important tissues, such as the fetal liver, skeletal muscle, and, importantly, the placenta. Through this review, we will delineate the key regulatory pathways involved in fetal programming based on the dietary maternal mineral supply and its crosstalk with epigenomic regulation in cattle.

Periconceptual Maternal Nutrition Affects Fetal Liver Programming of Energy- and Lipid-Related Genes

During pregnancy, the fetus relies on the dam for its nutrient supply. Nutritional stimuli during fetal organ development can program hepatic metabolism and function. Herein, we investigated the role of vitamin and mineral supplementation (VTM or NoVTM-at least 71 days pre-breeding to day 83 of gestation) and rate of weight gain (low (LG) or moderate (MG)-from breeding to day 83) on the fetal liver transcriptome and the underlying biological pathways. Crossbred Angus beef heifers (n = 35) were randomly assigned to one of four treatments in a 2 × 2 factorial design (VTM_LG, VTM_MG, NoVTM_LG, and NoVTM_MG). Gene expression was measured with RNA-Seq in fetal livers collected on day 83 ± 0.27 of gestation. Our results show that vitamin and mineral supplementation and rate of weight gain led to the differential expression of hepatic genes in all treatments. We identified 591 unique differentially expressed genes across all six VTM-gain contrasts (FDR ≤ 0.1). Over-represented pathways were related to energy metabolism, including PPAR and PI3K-Akt signaling pathways, as well as lipid metabolism, mineral transport, and amino acid transport. Our findings suggest that periconceptual maternal nutrition affects fetal hepatic function through altered expression of energy- and lipid-related genes.

Fetal Hepatic Lipidome Is More Greatly Affected by Maternal Rate of Gain Compared with Vitamin and Mineral Supplementation at day 83 of Gestation

Herein, we evaluated the hepatic lipid metabolic profiles of bovine fetuses in response to maternal vitamin and mineral supplementation (VMSUP; supplemented (VTM) or not (NoVTM)) and two different rates of gain (GAIN; low gain (LG), 0.28 kg/d, or moderate gain (MG), 0.79 kg/d). Crossbred Angus heifers (n = 35; initial BW = 359.5 ± 7.1 kg) were randomly assigned to a 2 × 2 factorial arrangement, resulting in the following treatment combinations: NoVTM-LG (n = 9), NoVTM-MG (n = 9), VTM-LG (n = 9), and VTM-MG (n = 8). Heifers received their treatments until d 83 of gestation, when they were ovariohysterectomized. Fetuses were harvested and liver samples were analyzed via ultrahigh-performance liquid chromatography-tandem mass spectroscopy to characterize lipid profiles and abundances. We identified 374 biochemicals/metabolites belonging to 57 sub-pathways of the lipid metabolism super-pathway. The majority of the biochemicals/metabolites (n = 152) were significantly affected by the main effect of GAIN. Maternal moderate rates of gain resulted in greater abundances (p ≤ 0.0001) of ω-3 fatty acids (eicosapentaenoate, docosapentaenoate, and docosahexaenoate) and lower abundances (p ≤ 0.0001) of ω-6 fatty acids. Further, MG resulted in the accumulation of several diacylglycerols and depletion of the majority of the monoacylglycerols. Concentrations of nearly all acylcarnitines (p ≤ 0.03) were decreased in VTM-LG fetal livers compared to all other treatment combinations, indicating a greater rate of complete oxidation of fatty acids. Levels of secondary bile acids were impacted by VMSUP, being greater (p ≤ 0.0048) in NoVTM than in VTM fetal livers. Moreover, NoVTM combined with lower rate of gain resulted in greater concentrations of most secondary bile acid biochemicals/metabolites. These data indicate that maternal diet influenced and altered fetal hepatic lipid composition in the first trimester of gestation. Maternal body weight gain exerted a greater influence on fetal lipid profiles than vitamin and mineral supplementation. Specifically, lower rate of gain (0.28 kg/d) resulted in an increased abundance of the majority of the biochemicals/metabolites identified in this study.

Using precision tools to manage and evaluate the effects of mineral and protein/energy supplements fed to grazing beef heifers

Our objectives were to develop a Mobile Cow Command Center (MCCC) capable of precision monitoring of grazing heifers to 1) examine the relationship between supplement intake on concentrations of liver mineral and blood metabolites and 2) examine activity, reproductive, and health behavior. Yearling crossbred Angus heifers (N = 60; initial BW = 400.4 ± 6.2 kg) were fitted with radio frequency identification ear tags that allowed access to electronic feeders (SmartFeed system; C-Lock Inc., Rapid City, SD), and with activity monitoring tags (CowManager B.V., the Netherlands) that monitored reproductive, feeding, and health-associated behaviors. Heifers were assigned randomly to one of three treatments for a 57-day monitoring period: 1) no supplement (CON; N = 20), 2) free choice mineral (MIN; Purina Wind and Rain Storm [Land O'Lakes, Inc.], N = 20), or 3) free choice energy and mineral supplement (NRG; Purina Accuration Range Supplement 33 with added MIN [Land O'Lakes, Inc.], N = 20). Consecutive day body weights, blood, and liver biopsies were collected at pasture turnout and final day of monitoring. By design, mineral intake was greatest in MIN heifers (49 ± 37 g/d) and energy supplement intake was greatest in NRG heifers (1,257 ± 37 g/d). Final BW and ADG were similar among treatments (P > 0.42). Concentrations of glucose on day 57 were greater (P = 0.01) in NRG compared with CON and MIN heifers. Liver concentrations of Se and Fe on day 57 were greater (P < 0.05) in NRG heifers than CON, with MIN being intermediate. Activity tags reported NRG heifers spent less time eating (P < 0.0001) and more time (P < 0.0001) being "highly active" than MIN with CON heifers being intermediate. Data retrieved from activity tags identified 16 of 28 pregnant heifers exhibiting some type of estrus-associated behavior even after confirmation of established pregnancy. The activity monitoring system triggered a total of 146 health alerts from 34 of the 60 heifers monitored, but only 3 heifers of the heifers initiating an electronic health alert needed clinical treatment. However, animal care staff identified nine additional heifers that required treatment for which no electronic health alert was generated. The electronic feeders successfully controlled intake of individual heifers managed in groups pastures; however, the activity monitoring system misrepresented estrus and health events.

Effects of feeding a vitamin and mineral supplement to cow-calf pairs grazing native range

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.

Selenium supplementation and pregnancy outcomes

In vertebrates and invertebrates, selenium (Se) is an essential micronutrient, and Se deficiency or excess is associated with gonadal insufficiency and gamete dysfunction in both males and females, leading to implantation failure, altered embryonic development and, ultimately, infertility. During pregnancy, Se excess or deficiency is associated with miscarriage, pre-eclampsia (hypertension of pregnancy), gestational diabetes, fetal growth restriction and preterm birth. None of this is surprising, as Se is present in high concentrations in the ovary and testes, and work in animal models has shown that addition of Se to culture media improves embryo development and survival in vitro in association with reduced reactive oxygen species and less DNA damage. Selenium also affects uterine function and conceptus growth and gene expression, again in association with its antioxidant properties. Similarly, Se improves testicular function including sperm count, morphology and motility, and fertility. In animal models, supplementation of Se in the maternal diet during early pregnancy improves fetal substrate supply and alters fetal somatic and organ growth. Supplementation of Se throughout pregnancy in cows and sheep that are receiving an inadequate or excess dietary intake affected maternal whole-body and organ growth and vascular development, and also affected expression of angiogenic factors in maternal and fetal organs. Supplemental Se throughout pregnancy also affected placental growth, which may partly explain its effects on fetal growth and development, and also affected mammary gland development, colostrum yield and composition as well as postnatal development of the offspring. In conclusion, Se supplementation in nutritionally compromised pregnancies can potentially improve fertility and pregnancy outcomes, and thereby improve postnatal growth and development. Future research efforts should examine in more detail and more species the potential benefits of Se supplementation to reproductive processes in mammals.

Vitamin and Mineral Supplementation and Rate of Gain in Beef Heifers II: Effects on Concentration of Trace Minerals in Maternal Liver and Fetal Liver, Muscle, Allantoic, and Amniotic Fluids at Day 83 of Gestation

We evaluated the effects of vitamin and mineral supplementation (from pre-breeding to day 83 of gestation) and two rates of gain (from breeding to day 83 of gestation) on trace mineral concentrations in maternal and fetal liver, fetal muscle, and allantoic (ALF) and amniotic (AMF) fluids. Crossbred Angus heifers (n = 35; BW = 359.5 ± 7.1 kg) were randomly assigned to one of two vitamin and mineral supplementation treatments (VMSUP; supplemented (VTM) vs. unsupplemented (NoVTM)). The VMSUP factor was initiated 71 to 148 d before artificial insemination (AI), allowing time for the mineral status of heifers to be altered in advance of breeding. The VTM supplement (113 g·heifer−1·d−1) provided macro and trace minerals and vitamins A, D, and E to meet 110% of the requirements specified by the NASEM, and the NoVTM supplement was a pelleted product fed at a 0.45 kg·heifer−1·day−1 with no added vitamin and mineral supplement. At AI, heifers were assigned to one of two rates of gain treatments (GAIN; low gain (LG) 0.28 kg/d or moderate gain (MG) 0.79 kg/d) within their respective VMSUP groups. On d 83 of gestation fetal liver, fetal muscle, ALF, and AMF were collected. Liver biopsies were performed prior to VMSUP factor initiation, at the time of AI, and at the time of ovariohysterectomy. Samples were analyzed for concentrations of Se, Cu, Zn, Mo, Mn, and Co. A VMSUP × GAIN × day interaction was present for Se and Cu (p < 0.01 and p = 0.02, respectively), with concentrations for heifers receiving VTM being greater at AI and tissue collection compared with heifers not receiving VTM (p < 0.01). A VMSUP × day interaction (p = 0.01) was present for Co, with greater (p < 0.01) concentrations for VTM than NoVTM at the time of breeding. VTM-MG heifers had greater concentrations of Mn than all other treatments (VMSUP × GAIN, p < 0.01). Mo was greater (p = 0.04) for MG than LG, while Zn concentrations decreased throughout the experiment (p < 0.01). Concentrations of Se (p < 0.01), Cu (p = 0.01), Mn (p = 0.04), and Co (p = 0.01) were greater in fetal liver from VTM than NoVTM. Mo (p ≤ 0.04) and Co (p < 0.01) were affected by GAIN, with greater concentrations in fetal liver from LG than MG. In fetal muscle, Se (p = 0.02) and Zn (p < 0.01) were greater for VTM than NoVTM. Additionally, Zn in fetal muscle was affected by GAIN (p < 0.01), with greater concentrations in LG than MG. The ALF in VTM heifers (p < 0.01) had greater Se and Co than NoVTM. In AMF, trace mineral concentrations were not affected (p ≥ 0.13) by VMSUP, GAIN, or their interaction. Collectively, these data suggest that maternal nutrition pre-breeding and in the first trimester of gestation affects fetal reserves of some trace minerals, which may have long-lasting impacts on offspring performance and health.

Vitamin and Mineral Supplementation and Rate of Weight Gain during the First Trimester of Gestation in Beef Heifers Alters the Fetal Liver Amino Acid, Carbohydrate, and Energy Profile at Day 83 of Gestation

The objective of this study was to evaluate the effects of feeding heifers a vitamin and mineral supplement and targeting divergent rates of weight gain during early gestation on the fetal liver amino acid, carbohydrate, and energy profile at d 83 of gestation. Seventy-two crossbred Angus heifers were randomly assigned in a 2 × 2 factorial arrangement to one of four treatments comprising the main effects of vitamin and mineral supplementation (VTM or NOVTM) and feeding to achieve different rates of weight gain (low gain [LG] 0.28 kg/day vs. moderate gain [MG] 0.79 kg/day). Thirty-five gestating heifers with female fetuses were ovariohysterectomized on d 83 of gestation and fetal liver was collected and analyzed by reverse phase UPLC-tandem mass spectrometry with positive and negative ion mode electrospray ionization, as well as by hydrophilic interaction liquid chromatography UPLC-MS/MS with negative ion mode ESI for compounds of known identity. The Glycine, Serine, and Threonine metabolism pathway and the Leucine, Isoleucine, and Valine metabolism pathway had a greater total metabolite abundance in the liver of the NOVTM-LG group and least in the VTM-LG group (p < 0.01). Finally, both the TCA Cycle and Oxidative Phosphorylation pathways within the Energy Metabolism superpathway were differentially affected by the main effect of VTM, where the TCA cycle metabolites were greater (p = 0.04) in the NOVTM fetal livers and the Oxidative Phosphorylation biochemicals were greater (p = 0.02) in the fetal livers of the VTM supplemented heifers. These data demonstrate that the majority of metabolites that are affected by rate of weight gain or vitamin/mineral supplementation are decreased in heifers on a greater rate of weight gain or vitamin/mineral supplementation.