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 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.

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 ±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; 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.

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.

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.

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.

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.

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.

Nutritional Regulation of Embryonic Survival, Growth, and Development.

Maternal nutritional status affects conceptus development and, therefore, embryonic survival, growth, and development. These effects are apparent very early in pregnancy, which is when most embryonic losses occur. Maternal nutritional status has been shown to affect conceptus growth and gene expression throughout the periconceptual period of pregnancy (the period immediately before and after conception). Thus, the periconceptual period may be an important "window" during which the structure and function of the fetus and the placenta are "programmed" by stressors such as maternal malnutrition, which can have long-term consequences for the health and well-being of the offspring, a concept often referred to as Developmental Origins of Health and Disease (DOHaD) or simply developmental programming. In this review, we focus on recent studies, using primarily animal models, to examine the effects of various maternal "stressors," but especially maternal malnutrition and Assisted Reproductive Techniques (ART, including in vitro fertilization, cloning, and embryo transfer), during the periconceptual period of pregnancy on conceptus survival, growth, and development. We also examine the underlying mechanisms that have been uncovered in these recent studies, such as effects on the development of both the placenta and fetal organs. We conclude with our view of future research directions in this critical area of investigation.

The Nasopharyngeal, Ruminal, and Vaginal Microbiota and the Core Taxa Shared across These Microbiomes in Virgin Yearling Heifers Exposed to Divergent In Utero Nutrition during Their First Trimester of Gestation and in Pregnant Beef Heifers in Response to Mineral Supplementation.

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.

Vitamin and mineral supplementation and rate of gain during the first trimester of gestation affect concentrations of amino acids in maternal serum and allantoic fluid of beef heifers.

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 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 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.

The effects of maternal nutrition during the first 50 d of gestation on the location and abundance of hexose and cationic amino acid transporters in beef heifer uteroplacental tissues.

We hypothesized that maternal nutrition during the first 50 d of gestation would influence the abundance of hexose transporters, SLC2A1, SLC2A3, and SLC2A5, and cationic amino acid transporters, SLC7A1 and SLC7A2, in heifer uteroplacental tissues. Angus-cross heifers (n = 43) were estrus synchronized, bred via artificial insemination, and assigned at breeding to 1 of 2 dietary intake groups (CON = 100% of requirements to achieve 0.45 kg/d of BW gain or RES = 60% of CON intake) and ovariohysterectomized on day 16, 34, or 50 of gestation (n = 6 to 9/d) in a completely randomized design with a 2 × 3 factorial arrangement of treatments. Uterine cross-sections were collected from the horn ipsilateral to the corpus luteum, fixed in 10% neutral buffered formalin, sectioned at 5 µm, and stained via immunofluorescence for transporters. For each image, areas of fetal membrane (FM; chorioallantois), luminal epithelium (ENDO), superficial glands (SG), deep glands (DG), and myometrium (MYO) were analyzed separately for relative intensity of fluorescence as an indicator of transporter abundance. Analysis of FM was only conducted for days 34 and 50. No transporters in target areas were influenced by a day × treatment interaction (P ≥ 0.06). In ENDO, all transporters were differentially abundant from days 16 to 50 of gestation (P ≤ 0.04), and SLC7A2 was greater (P = 0.05) for RES vs. CON. In SG, SLC7A1 and SLC7A2 were greater (P ≤ 0.04) at day 34 vs. day 16. In DG, SLC2A3 and SLC7A1 were greater (P ≤ 0.05) for CON vs. RES heifers; furthermore, SLC7A1 was greater (P < 0.01) at day 50 vs. days 16 and 34 of gestation. In MYO, SLC7A1 was greater (P < 0.01) for CON vs. RES and was greater (P = 0.02) at days 34 and 50 vs. day 16. There were no differences in FM (P ≥ 0.06). Analysis of all uterine tissues at day 16 determined that SLC2A1, SLC2A3, and SLC7A2 were all differentially abundant across uterine tissue type (P < 0.01), and SLC7A1 was greater (P = 0.02) for CON vs. RES. Analysis of all uteroplacental tissues at days 34 and 50 demonstrated that all transporters differed (P < 0.01) across uteroplacental tissues, and SLC7A1 was greater (P < 0.01) for CON vs. RES. These data are interpreted to imply that transporters are differentially affected by day of gestation, and that hexose and cationic amino acid transporters are differentially abundant across utero-placental tissue types, and that SLC7A1 is responsive to maternal nutritional treatment.

Feeding behavior, water intake, and energy and protein requirements of young Nellore bulls with different residual feed intakes.

This study aimed to determine feeding behavior, water intake (WI), and energy requirements of high- and low-residual feed intake (RFI) Nellore bulls. Data were collected from 42 weaned Nellore bulls (initial body weight [BW] 260 ± 8.1 kg; age 7 ± 1.0 mo) housed in a feedlot in group pens that contained electronic feeders, waterers, and a scale connected to the waterers. The individual dry matter intake (DMI), WI, and BW were recorded daily. The indexes of average daily gain (ADG), feed efficiency (gain to feed ratio), and RFI were calculated based on the data collected. The number of feeder and waterer visits and the time spent feeding or drinking water per animal per day were recorded as feeding behavior measures. Energy requirements for maintenance and gain were calculated according to the BR-CORTE system. Low-RFI bulls had lower DMI (P < 0.01) than high-RFI bulls, and no differences (P > 0.05) were observed between the two groups regarding WI, performance, and feeding behavior measurements. The net energy requirements for maintenance, metabolizable energy for maintenance, and efficiency of metabolizable energy utilization were 63.4, 98.6 kcal/metabolic empty body weight (EBW)0.75 daily, and 64.3%, respectively, for low-RFI bulls, and 78.1, 123.9 kcal/EBW0.75 daily, and 63.0%, respectively, for high-RFI bulls. The equations obtained for net energy for gain (NEg) were: NEg (Mcal/EBW0.75) daily = 0.0528 × EBW0.75 × EBG0.5459 for low-RFI and 0.054 × EBW0.75 × EBG0.8618 for high-RFI bulls, where EBG is the empty body gain. We did not observe any difference (P > 0.05) regarding the composition of gain in terms of protein or fat deposition between the two groups. Both groups also presented similar (P > 0.05) carcass and non-carcass traits. Therefore, our study shows that low-RFI Nellore bulls eat less, grow at a similar rate, and have lower maintenance energy requirements than high-RFI bulls. We also suggest that the lower feed intake did not compromise the carcass traits of more efficient animals, which would reduce production costs and increase the competitiveness of the Brazilian beef sector on the world market.

Fetal expression of genes related to metabolic function is impacted by supplementation of ground beef and sucrose during gestation in a swine model.

To determine the effects of maternal supplementation on the mRNA abundance of genes associated with metabolic function in fetal muscle and liver, pregnant sows (Landrace × Yorkshire; initial body weight (BW) 221.58 ± 33.26 kg; n = 21) fed a complete gestation diet (corn-soybean meal based diet, CSM) were randomly assigned to 1 of 4 isocaloric supplementation treatments: control (CON, 378 g/d CSM, n = 5), sucrose (SUGAR, 255 g/d crystalized sugar, n = 5), cooked ground beef (BEEF, 330 g/d n = 6), or BEEF + SUGAR (B+S, 165 g/d cooked ground beef and 129 g/d crystalized sugar, n = 5), from days 40 to 110 of gestation. Sows were euthanized on day 111 of gestation. Two male and 2 female fetuses of median BW were selected from each litter, and samples of the longissimus dorsi muscle and liver were collected. Relative transcript level was quantified via qPCR with HPRT1 as the reference gene for both muscle and liver samples. The following genes were selected and analyzed in the muscle: IGF1R, IGF2, IGF2R, GYS-1, IRS-1, INSR, SREBP-1C, and LEPR; while the following were analyzed in the liver: IGF2, IGF2R, FBFase, G6PC, PC, PCK1, FGF21, and LIPC. No effect of fetal sex by maternal treatment interaction was observed in mRNA abundance of any of the genes evaluated (P > 0.11). In muscle, the maternal nutritional treatment influenced (P = 0.02) IGF2 mRNA abundance, with B+S and SUGAR fetuses having lower abundance than CON, which was not different from BEEF. Additionally, SREBP-1 mRNA abundance was greater (P < 0.01) for B+S compared with CON, BEEF, or SUGAR fetuses; and females tended (P = 0.06) to have an increased abundance of SREBP-1 than males. In fetal liver, IGF2R mRNA abundance was greater (P = 0.01) for CON and BEEF than SUGAR and B+S; while FBPase mRNA abundance was greater (P = 0.03) for B+S compared with the other groups. In addition, maternal nutritional tended (P = 0.06) to influence LIPC mRNA abundance, with increased abundance in CON compared with SUGAR and B+S. These data indicate limited changes in transcript abundance due to substitution of supplemental sugar by ground beef during mid to late gestation. However, the differential expression of FBPase and SREBP-1c in response to the simultaneous supplementation of sucrose and ground beef warrants further investigations, since these genes may play important roles in determining the offspring susceptibility to metabolic diseases.

Prediction of water intake to Bos indicus beef cattle raised under tropical conditions1.

Water is the most important nutrient in animal nutrition; however, water intake is rarely measured. The objective of this study was to determine whether previously published water intake (WI) equations for beef cattle would accurately predict WI from four experiments conducted under tropical conditions. The experiments were conducted from 2013 to 2015. Nellore (Bos indicus) growing bulls (Exps. 1, 2, and 3) and heifers (Exp. 4) were used in the feedlot trials. In all experiments, animals were fed for ad libitum DMI. The WI, animal performance, diet composition, and environmental data were collected. The prediction of WI using the current published WI equations was evaluated by regressing predicted and measured WI values. The regression was evaluated using the two-hypothesis test: H0: ß0 = 0 and H0: ß1 = 1 and Ha: not H0. If both null hypotheses were not rejected, it was concluded that the tested equation accurately estimated WI. To develop a WI prediction equation based on the input variables, a leave-one-out cross-validation method was proposed. The proposed equation was evaluated using similar methodology described above. All previously published eight equations overestimated WI of cattle used in the four experiments conducted in southeast Brazil. A possible explanation for the overestimate of WI is that previously published WI equations were generated from data collected from predominantly Bos taurus cattle raised under temperate climates. From the data collected from experiments conducted with Nellore cattle in southeast Brazil, the proposed equation (WI = 9.449 + 0.190 × MBW + 0.271 × TMAX -0.259 × HU + 0.489 × DMI, where the MBW is the metabolic BW (kg0.75), TMAX is the maximum temperature (°C), HU is the humidity (%) and DMI in kg/d), more accurately to predicts WI of cattle raised under tropical conditions.

Oscillating and static dietary crude protein supply: II. Energy and protein requirements of young Nellore bulls.

The objective of this study was to evaluate whole body chemical composition and energy and protein nutrient requirements for maintenance and gain of Nellore bulls. Fifty young bulls, with an average age of 7 ± 1 mo and initial body weight (BW) of 260.0 ± 8.1 kg, were used in this experiment. Four bulls were used as baseline reference animals and were slaughtered at the beginning of the experiment. Four bulls were fed at maintenance (12 g dry matter [DM]/kg of BW), whereas 42 bulls were divided into six groups (n = 7/group) and were randomly assigned to the following dietary treatments 105 (low [LO]), 125 (medium [MD]), or 145 (high [HI]) g crude protein (CP)/kg DM, LO to HI (LH), LO to MD (LM), or MD to HI (MH) oscillating CP at a 48-h interval for 140 d. At the end of the experiment, bulls were slaughtered and samples of the whole body were collected. All samples were lyophilized, ground, and composed as percentage of component of empty body weight (EBW) from each bull. A power model was used to estimate carcass, non-carcass components, and gastrointestinal content of the shrunk body weight (SBW), and CP and water present in the empty body, whereas an exponential model was used to estimate adipose tissue and ether extract (EE) present in the EBW. Nonlinear regression equations were developed to predict heat production from metabolizable energy (ME) intake and retained energy (RE). The net energy requirements for maintenance and ME for maintenance were 77 and 122.75 kcal/EBW0.75/d, respectively. The efficiency of ME utilization for maintenance was 62.7%. The equation obtained for net energy for gain (NEg) was: NEg (Mcal/EBW0.75/d) = 0.0535 × EBW0.75 × EBG0.7131, where EBG is the empty body gain, and the efficiency was 24.25%. Net protein requirement for growth (NPg) was: NPg (g/d) = 227.372 × EBG - 19.479 × RE. There was a linear increase for carcass, CP, and water present in the EBW as the animal grew. The EE deposition exponentially increased as EBW increased.

Oscillating and static dietary crude protein supply. I. Impacts on intake, digestibility, performance, and nitrogen balance in young Nellore bulls.

Effects of dietary crude protein (CP) supply on intake, digestibility, performance, and N balance were evaluated in young Nellore bulls consuming static or oscillating CP concentrations. Forty-two young bulls (initial BW of 260 ± 8.1 kg; age of 7 ± 1.0 mo) were fed ad libitum and were randomly assigned to receive one of six diets with different CP concentrations for 140 d: 105 (LO), 125 (MD), or 145 g CP /kg DM (HI), and LO to HI (LH), LO to MD (LM), or MD to HI (MH) oscillating CP at a 48-h interval for each feed. At the end of the experiment, bulls were slaughtered to evaluate carcass characteristics. Linear and quadratic effects were used to compare LO, MD, and HI, and specific contrasts were applied to compare oscillating dietary CP treatments vs. MD (125 g CP/kg DM) static treatment. Dry matter intake (DMI) was not affected (P > 0.26) by increasing or oscillating dietary CP. As dietary N concentration increased, there was a subsequent increase in apparent N compounds digestibility (P = 0.02), and no significant difference (P = 0.38) was observed between oscillating LH and MD. Daily total urinary and fecal N increased (P < 0.01) in response to increasing dietary CP. Significant differences were observed between oscillating LM and MH vs. MD, where bulls receiving the LM diet excreted less (P < 0.01; 71.21 g/d) and bulls fed MH excreted more (P < 0.01) urinary N (90.70 g/d) than those fed MD (85.52 g/d). A quadratic effect was observed (P < 0.01) for retained N as a percentage of N intake, where the bulls fed LO had greater N retention than those fed HI, 16.20% and 13.78%, respectively. Both LH and LM had greater (P < 0.01) daily retained N when compared with MD. Performance and carcass characteristics were not affected (P > 0.05) by increasing or oscillating dietary CP. Therefore, these data indicate that although there is no alteration in the performance of growing Nellore bulls fed with oscillating CP diets vs. a static level of 125 g CP/kg DM, nor static low (105 g CP/kg DM) and high (145 g CP/kg DM) levels; there may be undesirable increases in environmental N excretion when the average dietary CP content is increased. The results suggest that dietary CP concentrations of 105, 125 g/kg DM, or within this range can be indicated for finishing young Nellore bulls, since it reaches the requirements, reduces the environmental footprint related to N excretion, and may save on costs of high-priced protein feeds.