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Primiparous ewes (n=32) were assigned to dietary treatments in a 2×2 factorial arrangement to determine effects of nutrient restriction and melatonin supplementation on maternal and fetal pancreatic weight, digestive enzyme activity, concentration of insulin-containing clusters and plasma insulin concentrations. Treatments consisted of nutrient intake with 60% (RES) or 100% (ADQ) of requirements and melatonin supplementation at 0 (CON) or 5 mg/day (MEL). Treatments began on day 50 of gestation and continued until day 130. On day 130, blood was collected under general anesthesia from the uterine artery, uterine vein, umbilical artery and umbilical vein for plasma insulin analysis. Ewes were then euthanized and the pancreas removed from the ewe and fetus, trimmed of mesentery and fat, weighed and snap-frozen until enzyme analysis. In addition, samples of pancreatic tissue were fixed in 10% formalin solution for histological examination including quantitative characterization of size and distribution of insulin-containing cell clusters. Nutrient restriction decreased (P⩽0.001) maternal pancreatic mass (g) and α-amylase activity (U/g, kU/pancreas, U/kg BW). Ewes supplemented with melatonin had increased pancreatic mass (P=0.03) and α-amylase content (kU/pancreas and U/kg BW). Melatonin supplementation decreased (P=0.002) maternal pancreatic insulin-positive tissue area (relative to section of tissue), and size of the largest insulin-containing cell cluster (P=0.04). Nutrient restriction decreased pancreatic insulin-positive tissue area (P=0.03) and percent of large (32 001 to 512 000 µm2) and giant (⩾512 001 µm2) insulin-containing cell clusters (P=0.04) in the fetus. Insulin concentrations in plasma from the uterine vein, umbilical artery and umbilical vein were greater (P⩽0.01) in animals receiving 100% requirements. When comparing ewes to fetuses, ewes had a greater percentage of medium insulin-containing cell clusters (2001 to 32 000 µm2) while fetuses had more (P

We hypothesized that maternal nutrition and day of gestation would impact utero-placental mRNA expression of the nutrient transporters GLUT1, GLUT5, CAT-1, CAT-2, and CAT-3 in beef heifers. Crossbred Angus heifers (n = 49) were estrous synchronized, bred via AI, assigned to nutritional treatment (CON = 100% of NRC requirements for 0.45 kg/d gain and RES = 60% of CON) and ovariohysterectomized on d 16, 34, or 50 of gestation (n = 6 to 9/d); Non-bred, non-pregnant (NB-NP) controls were fed the CON diet, not bred, and were ovariohysterectomized on d 16 of the synchronized estrous cycle (n = 6). The resulting arrangement of treatments was a 2 × 3 factorial + 1 (CON vs. RES × d 16, 34, or 50 + NB-NP controls). Caruncle (CAR), intercaruncular endometrium (ICAR), and fetal membranes (FM [chorioallantois]), were obtained from the pregnant uterine horn (the uterine horn containing the conceptus) immediately after ovariohysterectomy. On d 50 cotyledons (COT), intercotyledonary placenta (ICOT) and amnion (AMN) were also collected. Relative expression of nutrient transporters was determined for each tissue utilizing NB-NP-CAR and NB-NP-ICAR tissues as the baseline. For FM, NB-NP endometrium served as the baseline. There was no interaction of day × treatment (P ≥ 0.20) for any genes in CAR. However, CAR expression of GLUT1 was greater (P < 0.01) on d 16 compared with d 34 and 50, and GLUT5, CAT-1, and CAT-2 were greater (P ≤ 0.05) on d 34 compared with d 16 and 50. In ICAR, CAT-2 was the only gene to be influenced by the day × treatment interaction (P = 0.01), being greater in d 50 CON compared with d 34 CON and d 16 and 50 RES. In ICAR, expression of GLUT1 was greater (P < 0.01) on d 16 compared with d 34, and expression of CAT-1 was greater (P < 0.01) on d 34 and 50 compared with d 16. In FM, expression of GLUT5 was greater (P = 0.04) on d 16 compared with d 50 of gestation, and expression of CAT-1 was greater (P < 0.01) on d 34 and 50 compared with d 16. On d 50, expression of GLUT1, CAT-1, and CAT-3 expression were all greater (P < 0.05) in AMN compared with COT and ICOT, and expression of GLUT5 was greater (P < 0.01) in ICOT compared with COT and AMN. These data indicate that day was a more influential factor for mRNA expression of utero-placental glucose and cationic AA transporters than maternal nutritional status in heifers during early pregnancy.

We hypothesized that both day of gestation and maternal nutrition would alter the relative mRNA expression of neutral and acid AA transporters , , , , and . Crossbred Angus heifers ( = 49) were synchronized, bred via AI, assigned to nutritional treatment (100% of NRC requirements for 0.45 kg/d gain [control heifers {CON}] and 60% of CON [restricted heifers {RES}]), and ovariohysterectomized on d 16, 34, or 50 of gestation ( = 6 to 9/d). Nonbred, nonpregnant (NB-NP) controls were ovariohysterectomized on d 16 of the estrous cycle ( = 6) after synchronization. The resulting arrangement was a 2 × 3 factorial + 1 (CON vs. RES × d 16, 34, or 50 + NB-NP controls). Tissues collected included caruncular endometrium (CAR), intercaruncular endometrium (ICAR), fetal membranes (FM; chorioallantois; d 16 and 34), cotyledonary placenta (COT; d 50 only), intercotyledonary placenta (ICOT; d 50 only), and amnion (AMN; d 50 only]). Relative expression of , , , , and was determined for each tissue using NB-NP CAR and NB-NP ICAR tissues for the baseline; for FM, endometrium from NB-NP controls served as the baseline. In CAR, no day × treatment interaction was observed (0.05). However, day of gestation affected relative expression of , where expression on d 16 was greater (0.01) than expression on d 34 and 50. Additionally, relative expression of and was greater ( ≤ 0.05) in pregnant heifers compared with NB-NP heifers. For ICAR, was influenced by a day × treatment interaction (0.01), where expression in d 16 RES was greater ( ≤ 0.05) than that of any other day or nutritional treatment. Furthermore, expression in d 16 CON was greater ( ≤ 0.05) than that in d 50 RES, with those in d 34 CON and RES and d 50 CON being intermediate. In addition, was affected by day of gestation, where expression on d 16 was greater (0.01) than that on d 34 and 50. A day × treatment interaction was not observed (0.05) in FM; however, expression on d 34 was greater ( = 0.02) than on d 50, with that on d 16 being intermediate. Day of gestation also affected expression of , where expression on d 34 and 50 was greater (0.01) than that on d 16. These data support our hypothesis in that both day of gestation and maternal nutrition affected the relative mRNA expression of AA transporter in ICAR, whereas day of gestation has a greater effect on the relative mRNA expression of other neutral and acidic AA transporters in the various tissues studied.

We hypothesized that a standing flank ovariohysterectomy procedure could be developed in beef heifers that would provide high quality tissues for addressing critical questions during early pregnancy, while concomitantly keeping livestock stewardship a high priority. To test the hypothesis, we: 1) developed a standing flank ovariohysterectomy procedure for use in beef heifers, and 2) implemented this procedure in a cohort of heifers up to d 50 of pregnancy for tissue collections, documentation of post-surgical recovery, and assessment of feedlot finishing performance. Ovariectomy and cesarean section protocols are well established in research and veterinary medicine and were used as starting points for procedural development. Crossbred Angus heifers ( = 46; ∼ 15 mo of age; BW = 362.3 ± 34.7 kg) were used to develop this new surgical tissue collection technique. Heifers were subjected to the 5-d CO-Synch + CIDR estrous synchronization protocol so ovariohysterectomy occurred at d 16, 22, 28, 34, 40, and 50 of gestation. Key aspects of the standing flank ovariohysterectomy technique included 1) use of local anesthetic for a standing flank incision, 2) locate the uterine and ovarian arteries via blind palpation and ligate them through the broad ligament via an improved clinch knot, 3) cut the ovaries and uterus free from the broad ligament, 4) ligate the cervix and uterine branch of the vaginal artery, and 5) cut through the cervix and remove the reproductive tract. Surgical times, from skin incision to placement of the last suture, were influenced ( = 0.04) by stage of gestation. In pregnant heifers, time decreased from d 22 (120.0 ± 12.0 min) of gestation to d 40 (79.5 ± 12.0 min) of gestation; then increased at d 50 (90.5 ± 14.7 min) of gestation. Using this procedure, we obtained uterine, placental, and embryo/fetal tissues that had experienced limited hypoxia, little or no trauma, and thus were excellent quality for scientific study. All heifers recovered from surgery quickly and were moved to a finishing period. During the finishing period, ovariohysterectomized heifers had a DMI of 13.8 kg, gained 1.99 ± 0.35 kg/d, and had a G:F of 0.145 over 132-d. The standing flank ovariohysterectomy technique represents a new and viable model to economically obtain high quality tissues for investigating critical biological mechanisms during early pregnancy in beef heifers.

Feed costs, a major expense in animal production, may be reduced by including locally and regionally grown crops and local crop processing byproducts in animal diets. About half of the U.S. sugarbeet crop is produced and processed in North Dakota and Minnesota. Therefore, sug­ arbeet byproducts are readily available to the region's live­ stock producers. Two experiments were conducted to characterize the ensiling properties of wet sugarbeet pulp (WBP; 25% DM). In Experiment 1, a 4 x 3 factorial treat­ ment arrangement was used to define responses of ensiling WBP based on 1) formulated silage dry matter (DM) con­ centrations of 25,30,35, and 40%, and 2) inclusion of liq­ uid feedstuffs (molasses, concentrated separator byprod­ uct, and corn steep liquor). Experiment 2 was designed to evaluate the addition of 0.41% urea to WBP silage. In Experiment 1, lactic acid production increased (linear, P < 0.01) with the addition of all liquid feedstuffs. Though volatile fatty acid concentration was greatest (quadratic, P < 0.01) at 30% DM for molasses and concentrated separa­ tor byproduct, total organic acid production was enhanced with increasing silage DM only for the molasses treatment (linear, P =0.002). As expected, in Experiment 2, ensiled products which included urea had greater crude protein

An experiment was conducted to characterize ensiling properties of wet sugarbeet pulp (WBP). A 6 x 4 x 2 facto­ rial arrangement of treatments was used to determine the effects of 1) formulated silage dry matter concentrations (DM) of 25, 30, 35, 40, 45, and 50%, 2) inclusion of dry feedstuffs (dry pelleted beet pulp, dry rolled corn, wheat midds, and dry corn gluten feed), and 3) addition of wet sugarbeet tailings (WBT; to make up 25% DM of ensiled product) on ensiling characteristics of WBP. Pre-calculat­ ed amounts of each feedstuff were individually weighed in triplicate, thoroughly mixed, and transferred to sealed buckets to initiate an anaerobic, fermentation environment for 47 d. Nutritive value (crude protein, soluble crude pro­ tein, and in vitro DM disappearance) of ensiled WBP was influenced by the addition of dry feedstuffs. The most desirable fermentation (associated with increased acid pro­ duction) of WBP-based silage occurred with inclusion of dry feedstuffs to achieve 35% DM. The results of our experiment indicate addition of dry feedstuffs can increase the DM and nutrient quality of WBP, while maintaining a quality fermentation environment.