ABSTRACT
The cotyledon and caruncle tissues provide a functional bridge between the fetus and the dam. However, the relationship between these tissues and the transcriptomic profile that underlies the tissue functions remains elusive. Herein we investigate the expression profile of cotyledon and caruncle from nulliparous beef heifers carrying female fetuses at day 83 of pregnancy to identify changes occurring across tissues that contribute to placental function and their tissue-specific roles. We identified 2654 differentially expressed genes [padj ≤ 0.05, abs(log2FC) ≥ 1], including nutrient transporters and paternally imprinted genes. We found key regulators of tissue function and differentiation, including FOXO4, GATA2, GATA3, and HAND1, rewired between the tissues. Finally, we shed light on the over-represented pathways related to immune tolerance, tissue differentiation and remodeling. Our findings highlighted the intricate and coordinated cross-talk between fetal-maternal tissues. They provided evidence of a fine-tuned gene regulatory network underlying pregnancy and tissue-specific function in the bovine placenta.
Subject(s)
Gene Regulatory Networks , Placenta , Animals , Cattle/genetics , Female , Fetus , Nutrients , Placenta/metabolism , Pregnancy , TranscriptomeABSTRACT
Objectives of this experiment were to characterize the effects of ram plane of nutrition on body composition, concentrations of hormones and metabolites, sperm characteristics, and offspring outcomes. Mature Rambouillet rams (nâ =â 24, BWâ =â 82.9â ±â 2.63 kg) were individually housed and randomly assigned to either a positive (POS; nâ =â 8), maintenance (MAINT; nâ =â 8), or negative (NEG; nâ =â 8) plane of nutrition for an 84-day feeding period. Rams were fed a common diet, with daily feed allocations adjusted weekly based on body weight (BW) to achieve the targeted weight gain or loss (approximately 12% of initial BW). On 0, 28, 56, and 84-d, body condition score (BCS) and scrotal circumference (SC) were recorded, and blood and semen were collected. Following the feeding period, rams were placed in pens with 10 ewes each for a 28-d breeding period. Ewes were managed similarly throughout gestation and body weight and measurements were recorded at birth and weaning. Data were analyzed as repeated measures in time where appropriate with the mixed procedure of SAS, and individual ram was the experimental unit for all analysis. Ram BW was influenced by a treatmentâ ×â day interaction (Pâ <â 0.001), with POS (0.12â ±â 0.01 kg) having greater daily weight change than MAINT (0.1â ±â 0.01 kg), which was greater than NEG (-0.12â ±â 0.01 kg). Ram BCS and SC were influenced by treatmentâ ×â day interactions (Pâ ≤â 0.01), being similar on day 0 but POS being greater than NEG by day 56. Concentrations of triiodothyronine (T3) and T3:T4 ratio exhibited treatmentâ ×â day interactions (Pâ ≤â 0.02), as POS had greater values than NEG by day 84 (Pâ ≤â 0.02). Concentration of insulin-like growth factor-1 was greater in POS than MAINT and NEG (Pâ ≤â 0.02), and non-esterified fatty acids and thyroxine (T4) were influenced by a day effect (Pâ ≤â 0.01), but testosterone was unaffected (Pâ ≥â 0.09). Minimal differences in semen volume, sperm concentration, motility, or morphology were observed among treatments (Pâ ≥â 0.31). A similar proportion of ewes bred by rams in the respective treatments lambed and weaned lambs (Pâ ≥â 0.54). Birth weight, chest circumference, and shoulder-hip length were greater (Pâ ≤â 0.05) in NEG lambs compared with POS and MAINT; however, no differences were detected in weaning weight and weaning body measurements (Pâ ≥â 0.40). Findings suggest paternal nutrition during the period of sperm development may influence offspring outcomes, potentially as a result of in-utero programming of paternal origin.
This study was conducted to evaluate whether ram nutrition during the spermatogenesis impacts their body composition, concentrations of circulating hormones and metabolites, semen characteristics, fertility, and subsequent offspring growth and development. Rams were managed on treatments to gain, lose, or maintain body weight over an 84-day period. The changes in ram body weight that were imposed by our treatments resulted in changes in body condition score, scrotal circumference, and concentrations of several metabolic hormones, including thyroid hormones and insulin-like growth factor-1. However, no differences in sperm concentration or motility were observed. After the 84-d feeding period, rams were placed with ewes for a 28-d breeding period and ewes were monitored throughout gestation, lambing, and until weaning of the resulting lambs. Although no differences in ewe pregnancy rates were observed after the breeding period, lamb birth weight and body measurements were greater in rams that lost weight during spermatogenesis. Thereafter, body weight and growth performance of offspring were similar among sire treatments, but continued evaluation of offspring throughout the postnatal period is necessary. These findings indicate that paternal nutrition during spermatogenesis can impact offspring outcomes, potentially through epigenetic alterations to the sperm and subsequent in-utero programming of paternal origin.
Subject(s)
Animal Nutritional Physiological Phenomena , Body Composition , Diet , Animals , Male , Female , Sheep/physiology , Sheep/growth & development , Diet/veterinary , Animal Feed/analysis , Semen/physiology , Semen/chemistry , Pregnancy , Random Allocation , Semen Analysis/veterinary , Birth Weight , Body WeightABSTRACT
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 (nâ =â 72, 14 to 15 mo of age, initial body weight [BW]â =â 380.4â ±â 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; nâ =â 36) or a basal diet plus a vitamin and mineral supplement (VTM; nâ =â 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, nâ =â 19; VTM, nâ =â 18) were rebred via AI 60 d after treatment initiation, and heifers gestating female fetuses (CON, nâ =â 7; VTM, nâ =â 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 (Pâ ≥â 0.32), calf organ weights (Pâ ≥â 0.21), and calf ovarian follicle counts (Pâ ≥â 0.13) were not affected by maternal treatment. Concentrations of Se and Co in calf serum and Se in calf liver were increased (Pâ ≤â 0.02) in VTM. Serum concentrations of Co and vitamin A in the dam were greater (Pâ ≤â 0.01) in supplemented compared with nonsupplemented dams, and serum concentrations of vitamin D were greater (Pâ ≤â 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.
Vitamins and minerals are essential for the reproduction, performance, skeletal support, and overall health of beef cattle. During pregnancy, vitamins and minerals are critical for proper fetal growth, development, and establishment of postnatal micronutrient reserves. The study objectives were to evaluate the impacts of vitamin and mineral supplementation to beef heifers throughout gestation on female offspring morphometric characteristics at birth, mineral status and blood metabolite/endocrine profiles of the dam and calf, histological evaluation of calf ovaries, and organ weights of the neonate at 30 h of age. We hypothesized that vitamin and mineral supplementation to the dam during pregnancy would increase calf size and organ masses, mineral status, and blood metabolite and hormone profiles. We observed no differences in calf body measurements, organ masses, and offspring ovarian reserve between calves from supplemented and nonsupplemented dams. However, Co, Se, and vitamin D status was increased in the supplemented dam and calf, and we propose that enhanced vitamin and mineral status at birth may support the underdeveloped immune system, growth performance, and overall health of the neonate in the postnatal period. Further research is warranted to investigate postnatal offspring health, performance, and efficiency of energy utilization in key metabolic tissues in the calf.
Subject(s)
Animal Feed , Animals, Newborn , Diet , Dietary Supplements , Vitamins , Animals , Cattle/physiology , Cattle/growth & development , Female , Pregnancy , Vitamins/administration & dosage , Vitamins/pharmacology , Animals, Newborn/growth & development , Animal Feed/analysis , Diet/veterinary , Animal Nutritional Physiological Phenomena , Minerals/metabolism , Minerals/pharmacology , Trace Elements/pharmacology , Trace Elements/administration & dosage , Trace Elements/blood , Random AllocationABSTRACT
Rambouillet rams were managed on either a positive (POS; gain 12% body weight [BW]; n = 8), maintenance (MAINT; maintain BW; n = 8), or negative (NEG; lose 12% BW; n = 8) plane of nutrition before breeding. Rams were bred to ewes (n = 10 per ram) that were managed similarly throughout gestation, and lambs were fed a common diet postnatally. Two ewe lambs (7.6 ± 0.02 months of age, BW = 47.1 ± 1.17 kg) from each sire were selected and within pair, randomly assigned to be managed for a moderate (MOD, 0.11 kg/d; n = 23) or accelerated (ACC, 0.20 kg/d; n = 22) rate of gain for 56 d. Ewe lamb BW was recorded on a weekly basis and blood was collected on d 0, 28, and 56 for analysis of insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), thyroxine (T4), glucose, blood urea nitrogen (BUN), and non-esterified fatty acids (NEFA). Intravenous glucose tolerance tests (IVGTT) were conducted from d -7 to -4 and d 57 to 64. A unilateral ovariectomy was performed and ovarian follicles were staged and counted macro and microscopically. Sire treatment × day and ewe treatment × day interactions were present for BW (P ≤ 0.05), where POS had slower growth than MAINT and NEG, and tended (P = 0.10) to have reduced average daily gain (ADG) when managed at an accelerated rate of gain.By design, ACC had greater BW and ADG than MOD (P < 0.05). Concentrations of IGF-1 and T4 were greater in ACC than MOD (P ≤ 0.05), and NEG tended to have greater concentrations of IGF-1 than POS and MAINT (P = 0.08). At the first IVGTT, concentration of insulin was influenced by a sire treatment × time interaction (P ≤ 0.05), suggesting impaired secretion in NEG-sires ewes, but no differences in area under the curve (AUC) for glucose, insulin, or their ratio (P ≥ 0.11). No interactive effects of sire and ewe treatment (P ≥ 0.52) were observed at the second IVGTT, but insulin and insulin:glucose ratio were influenced by sire treatment × time (P ≤ 0.02), as NEG had greater insulin concentration at 60 min than MAINT (P = 0.03) and greater AUC than POS and MAINT (P ≤ 0.04). No differences in ovary size, weight, or total counts of macro and microscopic follicles were observed (P ≥ 0.23). Ewes fed ACC had a greater number of small surface follicles (P = 0.02), whereas MOD tended to have a greater number of large surface follicles and tertiary follicles (P < 0.06). These findings suggest that paternal plane of nutrition influences female offspring physiology, particularly at varying growth rates.
ABSTRACT
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 (nâ =â 31, initial body weight [BW]â =â 412.5â ±â 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; nâ =â 14) or the basal diet plus 113 g heifer-1 d-1 of the vitamin and mineral supplement (VTM; nâ =â 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 (Pâ ≤â 0.05) from day 84 to calving, while concentrations of Cu decreased in VTM and CON (Pâ ≤â 0.05) from day 84 to calving. Calf liver concentrations of Se, Cu, Zn, and Co at birth were greater for VTM than CON (Pâ ≤â 0.05), but calf birth BW and body measurements were not different (Pâ =â 0.45). Placental Se, colostrum quantity, total Se, Cu, Zn, and Mn in colostrum were greater (Pâ ≤â 0.04) in VTM dams than CON. Finally, offspring from VTM dams were heavier than CON (Pâ <â 0.0001) from weaning through 15 mo of age. These results were coupled with greater (Pâ ≤â 0.04) blood glucose at birth, decreased (Pâ ≤â 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.
Great variation exists in management decisions to offer a vitamin and mineral supplement to cowcalf herds in the Northern Great Plains. Decisions to supplement (or not) vitamins/minerals during critical periods of fetal development may have lasting postnatal impacts on the offspring; however, there is a lack of reports focusing on the long-term offspring outcomes. Our objectives were to determine the impacts of supplementing vitamins/minerals during gestation in beef heifers on mineral status in the dam, calf, placenta, and colostrum; offspring postnatal performance and feeding behavior; blood metabolite and endocrine profiles; and puberty attainment in heifer calves. We observed enhanced hepatic mineral status in heifers receiving supplemental vitamins/minerals during pregnancy, at calving, and in their neonatal calves compared with non-supplemented cohorts. Calves born to supplemented dams had improved measures of growth during postnatal development, increased concentrations of key blood metabolites, and differences in body measurements and carcass ultrasound traits at post-weaning evaluation. These results suggest that fetal nutritional environment is pivotal for the long-term growth and success of the offspring. We hypothesize that fetal programming outcomes on the offspring in this experiment may have the potential to affect the subsequent generation of beef calves.
Subject(s)
Dietary Supplements , Vitamins , Cattle , Animals , Pregnancy , Female , Vitamins/pharmacology , Animal Feed/analysis , Placenta , Diet/veterinary , Minerals , Vitamin A , Vitamin KABSTRACT
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 (nâ =â 100; BWâ =â 369â ±â 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], nâ =â 50) or the basal diet plus an energy/protein supplement targeting 0.79 kg/d gain (moderate gain [MG], nâ =â 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, nâ =â 23; MG, nâ =â 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 62.3â ±â 4.13 and 220.3â ±â 4.13 postcalving. By design, MG dams were heavier (Pâ <â 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 (Pâ <â 0.001) in MG dams, whereas concentrations of NEFA were decreased (Pâ <â 0.001) in LG dams. Calves from MG dams were 2.14 kg heavier (Pâ =â 0.03) and had larger chest circumference (Pâ =â 0.04) at birth compared with LG cohorts. Heifers from MG dams continued to have greater (Pâ ≤â 0.03) BW gain and feed efficiency during the development period, but no differences were observed (Pâ ≥â 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.
Generally, beef heifers are managed on grazing pastures during early gestation, which are subject to fluctuations in forage quantity and quality. Variations in the nutrients available to the dam can impact the developing offspring during early gestation. Providing energy/protein supplements to grazing cattle is a method to ensure nutrient requirements are being met and to enhance the rate of gain. This study modeled the effects of pasture supplementation in beef heifers during early gestation to determine whether 2 rates of body weight (BW) gain alter maternal body composition and concentrations of hormones and metabolites, as well as changes to postnatal characteristics of the subsequent F1 generation heifer calves. The rate of gain affected the heifer's BW, body composition, and concentrations of key metabolites and hormones, which likely altered the nutritional environment experienced by the fetus. Subsequently, F1 offspring from supplemented dams had greater morphometric characteristics at birth and had greater BW gain, feed efficiency, and eating rate during the postweaning development period. However, body composition, concentrations of hormones and metabolites, other feeding behaviors, puberty attainment, and response to vaccination of offspring were not affected. Further research is warranted to investigate how the early gestational rate of BW gain impacts key metabolic organs and mechanisms involved in transferring programming outcomes to subsequent generations.
Subject(s)
Colostrum , Diet , Animals , Cattle/physiology , Cattle/growth & development , Pregnancy , Female , Diet/veterinary , Colostrum/chemistry , Vaccination/veterinary , Hormones/blood , Animal Feed/analysis , Gestational Weight Gain , Body CompositionABSTRACT
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.
ABSTRACT
Our aim was to investigate the effects of maternal (F0) body weight (BW) gain during the first 84 d of gestation on body composition, ovarian reserve, and hormonal and metabolic parameters of breeding-age F1 heifers, as well as the BW and morphometry of F2 fetuses. The study also evaluated the effect of maternal BW gain (F0) on the mRNA relative abundance of the small intestine of both F1 heifers and F2 fetuses. Crossbred Angus heifers (F0; nâ =â 100) were managed to gain 0.20 kg/d (low gain [LG], nâ =â 50) or 0.75 kg/d (moderate gain [MG], nâ =â 50) for the first 84 d of gestation. Subsequently, F0 dams were managed on a common forage-based diet for the rest of gestation until the weaning of the F1 offspring. At 15 mo of age, a subset of F1 heifers was randomly selected for the current experiment (nâ =â 8 LG and nâ =â 8 MG). Heifers were bred via artificial insemination (AI; day 0), then harvested on day 84 of gestation. On days -10, 42, and 84, BW was recorded, and blood was collected and analyzed for concentrations of glucose, non-esterified fatty acids, progesterone, insulin, and insulin-like growth factor-1. The weight of F1 carcasses, organs, gravid uteri, and F2 fetuses and organs were recorded at harvest. Visible follicles were counted on F1 ovaries at harvest, and histology was used to count microscopic follicles. Liver and jejunal samples from F1 heifers were collected to measure tissue oxygen consumption and jejunal samples from F1 heifers and F2 fetuses were collected for mRNA relative abundance analysis. BW of F1 heifers from MG dams tended to be 12 kg greater (Pâ =â 0.06) than for F1 heifers from LG dams. Concentrations of glucose were greater (Pâ =â 0.03) in F1 heifers from the MG group, with no differences in other blood metabolites or follicular populations (Pâ ≥â 0.16). Interestingly, mammary glands were heavier (Pâ =â 0.05), and placentas and body depth tended to be heavier and greater, respectively (Pâ ≤â 0.10), for F2 fetuses from F0 LG heifers. Oxygen consumption in the liver and jejunum, as well as mRNA relative abundance in the jejunum of F1 heifers, were not affected by F0 rate of gain (Pâ ≥â 0.16). However, the NDUFC1, SDHA, UQCR1, and PPARG genes were upregulated (Pâ ≤â 0.05) in the jejunum of F2 fetuses from the LG group. In conclusion, BW gain of F0 heifers during early gestation exerts subtle effects on pre-breeding BW and blood metabolites in F1 offspring, with impacts present in F2 placenta, mammary gland, and intestine.
Early gestation is a period of rapid development of the placenta and fetal organs. In some species, impacts of nutrition during gestation persist across generations. Thus, adequate nutrition is crucial for the offspring's future productivity and reproductive success. This study aimed to assess the impact of 2 rates of body weight gain (0.20 and 0.75 kg/d) in F0 dams during early gestation on the productive and reproductive outcomes of F1 progeny and the development of F2 fetuses. The results indicate that a moderate rate of body weight gain during early gestation did not affect the development of ovarian follicles in F1 offspring but increased the body weight of F1 heifers in the pre-breeding period and concentrations of blood glucose during gestation. There were tendencies of F0 nutrition to impact placental weight, F2 mammary gland weight, and intestinal mRNA relative abundance, which could have implications on nutrient supply to the developing fetus and on future lactation and metabolism. These findings highlight the complexity of multigenerational interactions in the context of maternal nutrition and provide valuable insights to optimize productivity and reproductive performance in livestock systems.
Subject(s)
Body Composition , Animals , Cattle/physiology , Female , Pregnancy , Intestine, Small , Fetus , Weight Gain , Gestational Weight Gain , Blood GlucoseABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Thirty-five crossbred Angus heifers (initial BW = 359.5 ± 7.1 kg) were randomly assigned to a 2 × 2 factorial design to evaluate effects of vitamin and mineral supplementation [VMSUP; supplemented (VTM) vs. unsupplemented (NoVTM)] and different rates of gain [GAIN; low gain (LG), 0.28 kg/d, vs. moderate gain (MG), 0.79 kg/d] during the first 83 d of gestation on dam hormone and metabolic status, fetal tissue and organ mass, and concentration of glucose and fructose in fetal fluids. The VMSUP was initiated 71 to 148 d before artificial insemination (AI), allowing time for mineral status of heifers to be altered in advance of breeding. At AI heifers were assigned their GAIN treatment. Heifers received treatments until the time of ovariohysterectomy (d 83 ± 0.27 after AI). Throughout the experiment, serum samples were collected and analyzed for non-esterified fatty acids (NEFA), progesterone (P4), insulin, and insulin-like growth factor 1 (IGF-1). At ovariohysterectomy, gravid reproductive tracts were collected, measurements were taken, samples of allantoic (ALF) and amniotic (AMF) fluids were collected, and fetuses were dissected. By design, MG had greater ADG compared to LG (0.85 vs. 0.34 ± 0.04 kg/d, respectively; p < 0.01). Concentrations of NEFA were greater for LG than MG (p = 0.04) and were affected by a VMSUP × day interaction (p < 0.01), with greater concentrations for NoVTM on d 83. Insulin was greater for NoVTM than VTM (p = 0.01). A GAIN × day interaction (p < 0.01) was observed for IGF-1, with greater concentrations for MG on d 83. At d 83, P4 concentrations were greater for MG than LG (GAIN × day, p < 0.01), and MG had greater (p < 0.01) corpus luteum weights versus LG. Even though fetal BW was not affected (p ≥ 0.27), MG fetuses had heavier (p = 0.01) femurs than LG, and VTM fetuses had heavier (p = 0.05) livers than those from NoVTM. Additionally, fetal liver as a percentage of BW was greater in fetuses from VTM (P = 0.05; 3.96 ± 0.06% BW) than NoVTM (3.79 ± 0.06% BW), and from LG (p = 0.04; 3.96 ± 0.06% BW) than MG (3.78 ± 0.06% BW). A VMSUP × GAIN interaction was observed for fetal small intestinal weight (p = 0.03), with VTM-MG being heavier than VTM-LG. Therefore, replacement heifer nutrition during early gestation can alter the development of organs that are relevant for future offspring performance. These data imply that compensatory mechanisms are in place in the developing conceptus that can alter the growth rate of key metabolic organs possibly in an attempt to increase or decrease energy utilization.
ABSTRACT
The objectives of this study were to investigate the effects of feeding 60% dried corn distillers grains plus solubles (DDGS) or the equivalent sulfur as calcium sulfate (CaSO4) on semen quality and performance characteristics in yearling bulls. Thirty-six half-sibling Angus bulls [291 ± 8.5 d; initial body weight (BW) = 320 ± 2.7 kg] were assigned to one of three diets: 1) 60% concentrate as corn (CON; S = 0.18%; n = 12); 2) 60% DDGS replacing corn (60DDGS; S = 0.55% DM; n = 12); 3) CON + equivalent sulfur of 60DDGS added as CaSO4 (SULF; S = 0.54%; n = 12). Bulls were fed for 112 d to target an average daily gain (ADG) of 1.6 kg/d. Blood samples were collected on d 0, 56, and 112, and evaluated for testosterone, thyroxine, triiodothyronine (T3) and glutathione peroxidase (GPx) activity. Ruminal H2S was measured on d 0, 14, and 42. Scrotal circumference and semen were collected on d 0, 28, 56, 84, and 112 to evaluate sperm characteristics and GPx activity in seminal plasma. A computer assisted semen analysis was used to evaluate kinematic profiles in motile and progressive sperm throughout the study. Data were analyzed as repeated measures using MIXED procedures of SAS. No differences (P ≥ 0.14) were observed for final BW, ADG, or scrotal circumference; however, SULF tended (P = 0.07) to have reduced gain:feed compared with CON, with 60DDGS being intermediate. Concentrations of ruminal H2S on d 42 were greatest (P < 0.01) for SULF. Increased ejaculate volume was observed for 60DDGS and CON (P < 0.01) compared with SULF. For motile populations of sperm, velocity on an average path (VAP) and curvilinear velocity (VCL) were reduced (P ≤ 0.02) for SULF compared with CON, with 60DDGS being intermediate. In progressively motile sperm throughout the study, VAP and VSL were reduced (P ≤ 0.05) in 60DDGS and SULF compared to CON. For VCL, SULF was reduced (P ≤ 0.02) compared with CON, with 60DDGS being intermediate. In serum, concentrations of T3 were reduced (P = 0.009) in 60DDGS compared with CON or SULF. A treatment by day interaction (P = 0.03) was observed for seminal plasma GPx. At d 56, GPx activity was greater (P = 0.03) for 60DDGS compared with CON, with SULF intermediate; and at d 112, 60DDGS had the greatest (P ≤ 0.02) GPx activity. Therefore, feeding 60% DDGS to developing bulls altered semen kinematics, T3 concentrations, and GPx activity leading to the conclusion that these differences may not be solely dependent on concentrations of dietary sulfur.
Subject(s)
Semen Analysis , Zea mays , Animal Feed/analysis , Animal Nutritional Physiological Phenomena , Animals , Cattle , Diet/veterinary , Male , Reproduction , Semen Analysis/veterinary , SulfurABSTRACT
Multiparous Rambouillet ewes (n = 32) were allocated in a completely randomized design to determine if rumen-protected L-arginine (RP-Arg) supplementation during mid- and late gestation would 1) alter maternal carotid artery hemodynamics and 2) affect circulating amino acids associated with arginine metabolism in dams from day 54 of gestation to parturition and in their offspring from birth to 54 d of age. Ewes were assigned to one of three treatments from day 54 ± 3.9 to parturition: control (CON; 100% nutrient requirements), restricted (RES; 60% of CON), and RES plus 180 mg RP-Argâ¢kg BW-1â¢d1 (RES-ARG). Ewes were penned individually in a temperature-controlled facility. Carotid artery hemodynamics was measured via Doppler ultrasound at day 50 and 130 of gestation. Maternal serum was collected at day 54 and 138 of gestation and at parturition. At parturition, lambs were immediately removed from their dams and reared independently. Lamb serum samples were collected at birth and 1, 3, 7, 33, and 54 d of age. Pulsatility index was the only hemodynamic measurement altered by dietary treatment, where day 130 measurements were greater (P ≤ 0.04) for RES and RES-ARG compared with CON. The change in pulsatility index was greater (P < 0.01) for RES compared with CON but tended to be intermediate (P ≥ 0.12) for RES-ARG. Maternal serum Arg, Cit, and Asp at day 138 were greater (P < 0.01) for CON compared with RES and RES-ARG; serum Orn at day 138 was greater (P = 0.04) for CON compared with RES. Maternal serum Cit at parturition was greater (P ≤ 0.03) for CON and RES-ARG compared with RES. Offspring serum Arg was affected by a maternal treatment by day of age interaction (P = 0.03), where at day 3, CON and RES-ARG had greater (P ≤ 0.03) serum Arg concentrations than RES, and at day 54, RES-ARG was greater than (P = 0.002) CON and RES was intermediate and did not differ from (P ≥ 0.09) CON and RES-ARG. Offspring serum Orn and Cit were less (P ≤ 0.03) for RES and RES-ARG compared with CON. Results indicate that distal tissue blood perfusion decreased due to maternal RES, and RES-ARG was able to improve perfusion but not to the level of CON ewes. Further, maternal RP-Arg altered offspring Arg and related amino acid concentrations during the postnatal period.
Subject(s)
Arginine , Rumen , Amino Acids , Animal Nutritional Physiological Phenomena , Animals , Carotid Arteries , Diet/veterinary , Dietary Supplements , Female , Hemodynamics , Maternal Nutritional Physiological Phenomena , Pregnancy , SheepABSTRACT
In the present study, we evaluated whether the nasopharyngeal, ruminal, and vaginal microbiota would diverge (1) in virgin yearling beef heifers (9 months old) due to the maternal restricted gain during the first trimester of gestation; and (2) in pregnant beef heifers in response to the vitamin and mineral (VTM) supplementation during the first 6 months of pregnancy. As a secondary objective, using the microbiota data obtained from these two cohorts of beef heifers managed at the same location and sampled at the same time, we performed a holistic assessment of the microbial ecology residing within the respiratory, gastrointestinal, and reproductive tract of cattle. Our 16S rRNA gene sequencing results revealed that both α and ß-diversity of the nasopharyngeal, ruminal and vaginal microbiota did not differ between virgin heifers raised from dams exposed to either a low gain (targeted average daily gain of 0.28 kg/d, n = 22) or a moderate gain treatment (0.79 kg/d, n = 23) during the first 84 days of gestation. Only in the vaginal microbiota were there relatively abundant genera that were affected by maternal rate of gain during early gestation. Whilst there was no significant difference in community structure and diversity in any of the three microbiota between pregnant heifers received no VTM (n = 15) and VTM supplemented (n = 17) diets, the VTM supplementation resulted in subtle compositional alterations in the nasopharyngeal and ruminal microbiota. Although the nasopharyngeal, ruminal, and vaginal microbiota were clearly distinct, a total of 41 OTUs, including methanogenic archaea, were identified as core taxa shared across the respiratory, gastrointestinal, and reproductive tracts of both virgin and pregnant heifers.
ABSTRACT
Yearling Angus bulls (n = 36) were assigned one of three diets: 1) 60 % concentrate as corn (CON, 0.2 % S, 13.4 % CP; n = 12); 2) 60 % dried corn distiller's grains plus solubles (60DDGS 0.5 % S, 22.0 % CP; n = 12); 3) CON diet + equivalent sulfur of 60DDGS as CaSO4 (SULF, 0.5 % S, 13.9 % CP; n = 12) to evaluate effects of feeding 60 % DDGS or sulfur as CaSO4 on mineral and metabolite concentrations in serum and seminal plasma. Treatment × day interactions (P < 0.03) were observed for serum Cu, Se, and Mo. For Cu at d 112, lesser (P < 0.01) concentrations were observed in bulls fed the 60DDGS compared to SULF and CON diets. There were greater (P < 0.01) concentrations of Se at d 112 in bulls fed 60DDGS than CON and SULF diets. Concentrations of Mo were greater at d 56 and 112 (P < 0.01) in bulls fed CON compared to SULF and 60DDGS diets. In seminal plasma, there were treatment × day interactions (P < 0.02) for Cu and Mo. For Cu, at d 112, there was a lesser (P < 0.01) concentration in the bulls fed SULF compared to CON and 60DDGS diets. For Mo, there was a greater (P < 0.01) concentration in bulls fed the CON than 60DDGS and SULF diets at d 56 and 112. Changes in mineral and metabolite concentrations may have effects on bull reproductive performance when there is a relatively greater dietary sulfur content.
Subject(s)
Animal Feed/analysis , Calcium Sulfate/administration & dosage , Cattle , Diet/veterinary , Minerals/blood , Semen/chemistry , Amino Acids/chemistry , Amino Acids/metabolism , Animal Nutritional Physiological Phenomena , Animals , Calcium Sulfate/pharmacology , Dietary Supplements , Glucose/chemistry , Glucose/metabolism , Male , Minerals/metabolism , Urea/metabolism , Zea maysABSTRACT
The objective of this study was to evaluate the effects of feeding vitamin and mineral (VTM) supplement and (or) rate of gain (GAIN) during early gestation on amino acid (AA) concentrations in allantoic fluid (ALF) and amniotic fluid (AMF) and maternal serum. Seventy-two crossbred Angus heifers (initial BW = 359.5 ± 7.1 kg) were randomly assigned to one of four treatments in a 2 × 2 factorial arrangement with main effects of VTM supplement (VTM or NoVTM) and rate of gain (GAIN; low gain [LG], 0.28 kg/d, vs. moderate gain [MG], 0.79 kg/d). The VTM treatment (113 gâ¢heifer-1â¢d-1, provided macro and trace minerals and vitamins A, D, and E to meet 110% of the requirements specified by the NASEM in Nutrient requirements of beef cattle. Washington, DC: The National Academies Press. doi:10.17226/19014, 2016) was initiated 71 to 148 d before artificial insemination (AI). To complete the factorial arrangement of treatments, at breeding heifers were either maintained on the basal diet (LG), or received MG diet which was implemented by adding a protein/energy supplement to the LG diet. Thirty-five gestating heifers with female fetuses were ovariohysterectomized on d 83 of gestation and maternal serum, ALF, and AMF were collected. Samples were analyzed for concentrations of neutral AA: Ala, Asn, Cys, Gln, Gly, Ile, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val; cationic AA: Arg, His, and Lys; and anionic AA: Asp and Glu. In serum, a VTM × GAIN interaction (P = 0.02) was observed for Glu, with greater concentrations for VTM-LG than VTM-MG. Concentrations of serum Cys, Met, and Trp were greater (P ≤ 0.03) for MG than LG. In ALF, concentrations of Glu were affected by a VTM × GAIN interaction, where VTM-MG was greater (P < 0.01) than all other treatments. Further, ALF from VTM had increased (P ≤ 0.05) concentrations of His, Asp, and 12 of the 14 neutral AA; whereas GAIN affected concentrations of Arg, Cys, and Asp, with greater concentrations (P ≤ 0.05) in MG heifers. In AMF, AA concentrations were not affected (P ≥ 0.10) by VTM, GAIN, or their interaction. In conclusion, increased concentrations of AA in maternal serum and ALF of beef heifers were observed at d 83 of gestation in response to VTM supplementation and rate of gain of 0.79 kg/d, which raises important questions regarding the mechanisms responsible for AA uptake and balance between the maternal circulation and fetal fluid compartments.