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To determine the effects of late gestational nutrient restriction on expelled cotyledonary mRNA expression, fall-calving Hereford × Simmental-Angus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 11) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth. Beginning on d 160 of gestation, heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME/kg, 6.69% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Calving was observed for all females and placentas were collected at natural expulsion. Immediately after collection (average: 4.5 h post-calving; range: 2.3 to 12.1 h post-calving), 2 representative cotyledons on the ipsilateral side were cleaned with phosphate buffered saline, and cotyledonary tissue was flash frozen. Total RNA was extracted, and RT-qPCR was performed for mRNA expression of glucose transporters (SLC2A1, SLC2A3, SLC2A4), a fructose transporter (SLC2A5), amino acid transporters (SLC1A1, SLC3A2, SLC7A1, SLC7A5, SLC7A8, SLC38A2), angiogenic factors/receptors (VEGFA, NOS3, FLT1, KDR, GUCY1B3), and pregnancy-associated glycoprotein 2 (PAG2). Relative mRNA expression was analyzed with nutritional plane, treatment initiation date, time to cotyledon sampling, and calf sex (when P < 0.25) as fixed effects. We have previously reported that total uterine blood flow during late gestation was not affected (P = 0.20) by nutritional plane or the nutritional plane × day of gestation interaction. Post-calving, NR dams were 64 kg BW less (P < 0.001) and 2.0 BCS less (P < 0.001), but calf birth weight was not affected (P = 0.72) by nutritional plane. Contralateral placental dry weight tended to be less (P = 0.07) in NR dams, but total placental weight was not affected (P = 0.86) by late gestational nutritional plane. Cotyledonary relative mRNA expression of SLC2A3 and SLC38A2 was greater (P = 0.05) and relative expression of SLC2A1, SLC2A4, and NOS3 tended to be greater (P = 0.07) in NR dams compared with CON. Late gestational nutritional plane did not affect (P = 0.13) cotyledonary relative mRNA expression of FLT1, GUCY1B3, KDR, PAG2, SLC1A1, SLC2A5, SLC3A2, SLC7A1, SLC7A5, SLC7A8, and VEGFA. In summary, first parity beef females who experienced late gestational nutrient restriction maintained uterine blood flow and placental mass and had 4 nutrient transporters and 1 angiogenic factor upregulated in cotyledons, all which likely contributed to their conservation of fetal growth. [ABSTRACT FROM AUTHOR]

We hypothesized that maternal circulating AA concentrations would be reduced by late gestational nutrient restriction, indicating less available nutrients for transport by the uteroplacenta to the growing fetus. Fall-calving Hereford-SimAngus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 12) or 70% (NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME, 6.66% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Jugular blood samples were obtained on days 159 (Pre-treatment), 202, and 244 of gestation, and 1 h post-calving to determine serum concentrations of the 20 common AA (except cysteine), 1-methyl histidine, and 3-methyl histidine. Gestational and post-calving AA were analyzed separately with nutritional plane, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Gestational AA included day and nutritional plane x day using repeated measures. We have previously reported that dam BCS was less (P ≤ 0.04) by day 202 of gestation and dam BW was less (P ≤ 0.01) by day 223 of gestation for NR dams. Post-calving, NR dams were 64 kg BW and 2.0 BCS lless (P < 0.001), but calf birth weight was not affected (P = 0.72) by nutritional plane. Histidine, lysine, and methionine were greater (P ≤ 0.03) in NR dams on day 202 of gestation. Tryptophan and valine were less (P ≤ 0.05) while methionine and total AA tended to be less (P ≤ 0.08) on day 244 of gestation in NR dams. Aspartic acid, glutamic acid, and tyrosine were less (P ≤ 0.03), but 3-methyl histidine was greater (P ≤ 0.01) on days 202 and 244 of gestation in NR dams. 1-methyl histidine was greater (P ≤ 0.05) at all 3 gestational timepoints but leucine was less (P = 0.03) in NR dams during gestation. Post-calving, glutamic acid, leucine, and valine were less (P ≤ 0.04), and methionine, threonine, tryptophan, tyrosine, and total AA tended to be less (P ≤ 0.10) in NR dams. Histidine, 1-methyl histidine, 3-methyl histidine, and serine were greater (P ≤ 0.03) in NR dams post-calving. In summary, late gestational nutrient restriction reduced total maternal circulating AA and altered the maternal serum AA profile, but calf birth weight was not affected. Individual AA that were greater or unaffected in NR dams were likely indicative of body protein catabolism occurring to meet nutrient requirements. [ABSTRACT FROM AUTHOR]

We hypothesized that cows grazing stockpiled tall fescue (STF) during late gestation would have increased nutrient intake, resulting in improved metabolic status and fetal growth compared with cows consuming summer-baled tall fescue hay. Multiparous, spring-calving, crossbred beef cows (year 1: n = 48, year 2: n = 56) were allocated by body weight (BW), body condition score (BCS), age, service sire, and expected calving date to 1 of 2 forage systems (4 rep/system) in mid-November on day 188 of gestation: strip-graze endophyte- infected STF in 4.05 ha pastures or consume ad libitum endophyte-infected summer-baled tall fescue-based hay in uncovered dry lots. Treatments were terminated 1 wk postpartum, and cow-calf pairs were managed together until weaning. Data were analyzed with forage system, year, and their interaction as fixed effects. Sampling day was a repeated effect for cow metabolites and hormones. Calf date of birth was in the model when P < 0.25; pasture or pen was the experimental unit. Cow prepartum BW was not affected (P . 0.424) by forage system, but cows grazing STF tended (P = 0.09) to have greater BCS at day 35 and had greater (P = 0.03) final precalving BCS than hay-fed cows. Additionally, final precalving 12th rib fat thickness tended (P = 0.09) to be greater for STF than hay-fed cows. Calves born to cows fed hay only weighed 10.2% less (P = 0.03) at birth than calves born to cows consuming STF, indicating reduced fetal growth. Postpartum cow BW, BCS, first service conception rate, and overall pregnancy rate were not affected (P . 0.15) by late gestational forage system. After day 0, serum urea N was greater (P < 0.001) in cows consuming STF on all days measured. Cows grazing STF also tended (P = 0.08) to have greater plasma glucose than cows consuming hay. Serum nonesterified fatty acids (NEFA) were greater (P < 0.001) in cows grazing STF on day 56 in year 1 and on day 77 and 99 in year 2. Serum triiodothyronine was less (P = 0.03) on day 0, but greater (P = 0.004) on day 99, in cows grazing STF. Cows grazing STF tended (P = 0.06) to have greater thyroxine on day 77 in year 1. Serum cortisol was greater (P = 0.003) on day 35 and tended (P = 0.10) to be greater on day 99 in cows grazing STF. Calf birth weight was positively correlated with prepartum maternal serum urea N (r = 0.31, P = 0.002) and NEFA (r = 0.12, P = 0.005). In this study, cows grazing STF had increased nutrient intake during late gestation, resulting in greater fetal growth. [ABSTRACT FROM AUTHOR]

Our objectives were to determine changes in colostrum yield and composition across the 36 hours post-calving and effects of late gestational nutrient restriction (NR) on these changes. Fall-calving, crossbred beef heifers (BW: 472 ± 33 [SD] kg; BCS: 5.4 ± 0.5) were individually fed 100% (control; CON; n = 13) or 70% (NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, growth, and pregnancy from d 160 of gestation to parturition. Calves were removed from dams immediately post-calving and pre-suckling. Colostrum was handmilked from all quarters at 1, 12, 24, and 36 h to determine total colostrum volume and weight. Colostrum protein, triglycerides, and milk urea nitrogen (MUN) concentration were analyzed using colorimetric assays on a UV-visible light microplate reader. Data were analyzed using fixed effects of treatment, hour, treatment × hour (repeated measures); calf sex, maternal sire, and treatment initiation date were covariates. Colostrum yield was affected (P < 0.02) by the treatment × hour interaction. Colostrum volume and weight were 28% less (P = 0.03) for NR than CON at 1 h. For both treatments, colostrum volume and weight decreased (P = 0.04) from 1 to 12 h, before increasing (P = 0.02) from 12 to 36 h. Triglyceride concentration was greater (P = 0.03) in NR than CON. Both triglyceride concentration and total protein decreased (P = 0.01) from 1 to 24 h. Protein concentration decreased (P < 0.001) from 1 to 36 h. Total triglycerides and MUN decreased (P < 0.001) from 1 to 12 h, before total MUN increased (P < 0.001) from 12 to 36 h and total triglycerides increased (P = 0.004) from 24 to 36 h. In conclusion, nutrient restriction may only affect colostrum yield at 1 h, and colostrum nutrient content decreases dramatically after the first milking. [ABSTRACT FROM AUTHOR]

To investigate the effects of maternal selenium (Se) supplementation and nutritional intake during gestation on hormone changes, percentage body weight (BW) change, and organ mass in neonatal lambs, ewes were allocated to differing Se levels (adequate Se (ASe, 11.5 mg/kg BW) or high Se (HSe, 77.0 mg/kg BW)) initiated at breeding and nutritional intake (60% (RES), 100% (CON), or 140% (HIGH) of NRC requirements) initiated at day 40 of gestation. At parturition, all lambs were removed from dams, fed common diets, and BWand blood samples were collected until day 19. There was a Se!nutritional intake!day interaction for percentage BW change from birth. Lambs born to ASe-HIGH ewes tended to have decreased BW change compared with ASe-CON and ASe-RES groups on day 7. Lambs from HSe-HIGH ewes tended to have increased BW change compared with HSe-RES and HSe-CON groups from days 7 to 19. At birth, there was a Se!sex of offspring interaction, in which male lambs from HSe ewes had decreased cortisol concentrations compared with all other lambs. By 24 h, lambs from RES ewes had decreased cortisol compared with those from HIGH ewes, with lambs from CON ewes being intermediate. Lambs from RES- and CON-fed ewes had greater thyroxine than HIGH ewes at 24 h. Organ masses on day 19 were mainly impacted by maternal nutritional intake and sex of the offspring. Birth weight alone did not predict growth performance during neonatal life. Moreover, despite a similar postnatal diet, maternal nutritional plane and Se status did impact neonatal endocrine profiles. Exact mechanisms of how neonatal endocrine status can influence later growth and development need to be determined. [ABSTRACT FROM AUTHOR]

To determine effects of late gestational nutrient restriction (NR) on neonatal blood chemistry and hematology, primiparous fall-calving crossbred beef heifers [BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] were individually fed either 100% (control; CON; n = 12) or 70% (n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to parturition. Calf jugular blood was obtained at 0 (pre-suckling), 6, 12, 24, and 48 h postnatally to determine serum chemistry and complete blood cell count. Data were analyzed with fixed effects of treatment, hour, and their interaction, using repeated measures. Calving date was a fixed effect; calf sex was included when P < 0.25. The treatment x hour interaction (P < 0.10) affected total protein, globulin, gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), creatinine, creatine kinase, red blood cells (RBC), hemoglobin, hematocrit, sodium, anion gap, and potassium. Total protein and globulin at 6 to 48 h were greater (P = 0.02) in NR calves. Calves from NR heifers had greater (P < 0.08) GGT at 6, 12, and 48 h and greater (P = 0.07) AST at 0 to 24 h. Creatinine at 24 h and creatine kinase at 6 to 24 h were greater (P < 0.04) in NR calves. Hematocrit from 6 to 24 h and RBC and hemoglobin at 6 and 12 h were greater (P = 0.09) in CON calves. Sodium from 0 to 48 h and anion gap at 6 h were greater (P < 0.09) in CON calves. Calves from NR heifers had greater (P = 0.03) 0 h potassium. Treatment affected chloride, which was greater (P = 0.08) in CON calves. These data indicate calves born to nutrient restricted heifers may experience more trauma at calving but have improved passive transfer. [ABSTRACT FROM AUTHOR]

To determine effects of late gestational maternal nutrient restriction (NR) on uteroplacental blood flow and placental growth, primiparous fall-calving crossbred beef heifers [BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 12) or 70% (n = 13) of energy and protein requirements for maintenance, pregnancy, and growth during the last 120 days of gestation. Transrectal color Doppler ultrasonography of both uterine arteries was conducted pretreatment and every 21 d during treatments. Placentas were split into ipsilateral and contralateral sides, dissected (cotyledonary vs. intercotyledonary), and dried. Data were analyzed with treatment, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Uterine blood flow included day and treatment x day (repeated measures). Dam BW was less (P ≤ 0.01) from d 223 of gestation through parturition for NR dams, but calf BW was not affected (P = 0.72) by treatment. The interaction affected (P < 0.01) heart rate, where NR dams had decreased heart rate after treatments began. Treatment did not affect (P ≥ 0.20) uterine artery blood flow or hemodynamics, but all variables were affected (P ≤ 0.04) by day. Contralateral total and cotyledonary weights tended (P ≤ 0.09) to be greater and ipsilateral and total cotyledonary:intercotyledonary ratios were greater (P ≤ 0.01) for CON. Cotyledon number, cotyledon size, and total cotyledonary, intercotyledonary, and placental weight were not affected (P ≥ 0.15) by treatment. Relative to dam BW, uterine blood flow was not affected (P = 0.83), but relative placental weight tended to be greater (P = 0.09) in NR dams. In the current study, NR dams lost maternal BW during late gestation and had less contralateral placental growth, yet uterine blood flow was maintained and placental size relative to BW ensured fetal growth similar to CON offspring. [ABSTRACT FROM AUTHOR]

We hypothesized that late gestational nutrient restriction (NR) would reduce colostrum yield and impair offspring transition to postnatal life. Primiparous, fall-calving crossbred beef heifers (BW: 451 ± 28 [SD] kg; BCS: 5.4 ± 0.7) were individually-fed either 100% (control; CON; n = 12) or 70% (n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to parturition. Delivery duration was determined as minutes from first fetal feet expulsion to birth. Calves were reared naturally by their dams and monitored for times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores (1 = very weak, 5 = extremely vigorous) were assigned at 2, 5, 10, and 20 min of age. Total colostrum from one rear quarter was collected pre-suckling. Calf rectal temperatures were recorded at 0, 6, 12, 24, and 48 h postnatally. Data were analyzed with the fixed effects of treatment (single point) or treatment, hour, and their interaction (over time, using repeated measures). Date of calving was a fixed effect; calf sex was included when P < 0.25. Heifers fed CON had greater (P = 0.04) colostrum weight and volume than NR. Although gestational nutrition did not affect (P = 0.72) calf birth weight, calves born to CON heifers had faster (P = 0.02) times to stand and tended to have faster (P = 0.09) times to attempt to stand. Calves from CON heifers had greater (P = 0.05) 20 min vigor scores. Rectal temperatures at 0 h were greater (P = 0.02) in CON calves, but at 24 h were greater (P = 0.04) in NR calves. These data indicate that heifers nutrient restricted during late gestation have reduced colostrum yield and less vigorous calves, which may influence postnatal calf survival. [ABSTRACT FROM AUTHOR]