Search

Compromised placental function can result in fetal growth restriction which is associated with greater risk of neonatal morbidity and mortality. Large increases in transplacental nutrient and waste exchange, which support the exponential increase in fetal growth during the last half of gestation, are dependent primarily on the rapid growth and vascularization of the uteroplacenta. The amplitude of melatonin secretion has been associated with improved oxidative status and altered cardiovascular function in several mammalian species; however, melatonin mediated alterations of uteroplacental capacity in sheep and cattle are lacking. Therefore, our laboratories are examining uteroplacental blood flow and fetal development during maternal melatonin supplementation. Using a mid- to late-gestation ovine model of intrauterine growth restriction, we examined uteroplacental blood flow and fetal growth during supplementation with 5 mg/d of dietary melatonin. Maternal nutrient restriction decreased uterine arterial blood flow, while melatonin supplementation increased umbilical arterial blood flow compared with non-supplemented controls. Although melatonin treatment did not rescue fetal weight in nutrient restricted ewes; we observed disproportionate fetal size and fetal organ development. Elevated fetal concentrations of melatonin may result in altered blood flow distribution during important time points of development. These melatonin specific responses on umbilical arterial hemodynamics and fetal development may be partially mediated through vascular melatonin receptors. Recently, we examined the effects of supplementing Holstein heifers with 20 mg/d of dietary melatonin during the last third of gestation. Uterine arterial blood flow was increased by 25% and total serum antioxidant capacity was increased by 43% in melatonin supplemented heifers vs. non-supplemented controls. In addition, peripheral concentrations of progesterone were decreased in melatonin supplemented heifers vs. non-supplemented controls. Using an in vitro model, melatonin treatment increased the activity of cytochrome P450 2C, a progesterone inactivating enzyme, which was blocked by treatment with the melatonin receptor antagonist, luzindole. Elucidating the consequences of specific hormonal supplements on the continual plasticity of placental function will allow us to determine important endogenous mediators of offspring growth and development.

ObjectivesA diet high in sucrose is reflective of a Western diet that the average American consumes. When consuming a Western diet, individuals consume roughly 20 teaspoons of sucrose per day. The Western diet has been previously linked to metabolic disorders such as diabetes and obesity, which may be prevented by replacing dietary sucrose with a healthy protein alternative like beef. The objectives of this study were to investigate the impact of substituting dietary sucrose with beef supplementation on maternal health and fetal development utilizing the sow as a biomedical model. Materials and MethodsMultiparous pregnant sows (Landrace × Yorkshire; BW = 222 kg; n = 21) were fed a complete sow gestation diet (corn-soybean meal-based, CSM; NRC 2017) at 1 percent of BW on sow d 30 of gestation at 700 h daily from d 30 to 39 of gestation. Sows were then fed CSM at 1 percent of BW on d 39 of gestation at 700 h daily from d 40 to 110 (± 0.58) of gestation. Sows were randomly assigned to 1 of 4 isocaloric dietary supplements consisting of 126 g CSM (CON, n = 5); 110 g cooked ground beef (CGB; BEEF, n = 6); 54.8 g CGB and 42.7 g sucrose (B+S, n = 5); or 85.5 g sucrose (SUCROSE, n = 5). Dietary supplements were fed 3 times daily from d 40 to 110 (± 0.58) of gestation. Sows were housed in gestation crates from d 30 to 111 (± 0.58) of gestation and euthanized on d 111 (± 0.58) of gestation. Blood was collected via jugular venipuncture from sows on d 29 and 111 (± 0.58) of gestation. Blood chemistry was immediately analyzed using iSTAT point-of-care device. Bodyweights were measured on d 30, 39, 54, 68, 82, 96, and 111 (± 0.58) of gestation. Tenth rib and last rib fat depth were measured on d 35, 70, and 110 (± 0.58) of gestation utilizing an ALOKA SSD-500V ultrasound. Fetal growth measurements were recorded for all fetuses. Two median weight male and female fetuses were selected from each sow for tissue collections which included pancreas, kidney, liver, heart, heart fat, lung, empty body weight, semimembranosus, and semitendinosus weights. A repeated measures design, using sow as the repeated measure, was modeled using the MIXED procedure of SAS (SAS Inst. Inc., Car, NC) using compound symmetry variance covariance matrix. Alpha level was 0.05. ResultsDietary treatment did not influence blood metabolites of sows on d 29 or 111 of gestation (P = 0.09 and P = 0.20, respectively). Sow weight throughout gestation was not influenced by dietary treatment (P = 0.74). Dietary treatment did not influence tenth rib or last rib fat depth on d 35, 70, or 110 of gestation (P = 0.27). Compared to CON and SUCROSE, fetuses from sows supplemented with BEEF had greater nose to crown lengths (6.03 ± 0.29, 6.02 ± 0.28, and 7.33 ± 0.36 cm, respectively; P = 0.04). Compared to CON, fetuses from sows supplemented with sucrose had respectively greater BW (1296 ± 73.6 vs. 1556 ± 68.8 g; P = 0.02); heart girths (22.90 ± 0.39 vs. 24.13 ± 0.39 cm; P = 0.03), and liver weights (36.48 ± 2.19 vs. 43.44 ± 2.05 g; P = 0.04). Dietary treatment did not influence other fetal characteristics or organ weights (P ≥ 0.05). ConclusionBeef supplementation during mid to late pregnancy had minimal effects on maternal blood metabolites, bodyweight, or backfat depth or fetal growth. The increase in fetal weight due to sucrose supplementation should be further explored.

The objectives were to investigate effects of nutritional plane and Se supply during gestation on yield and nutrient composition of colostrum and milk in first parity ewes. Rambouillet ewe lambs (n = 84, age = 240 ± 17 d, BW = 52.1 ± 6.2 kg) were allocated to 6 treatments in a 2 × 3 factorial array. Factors included Se [adequate Se (ASe, 11.5 µg/kg of BW) or high Se (HSe, 77.0 µg/kg of BW)] initiated at breeding, and nutritional plane [60 (RES), 100 (CON), or 140% (HIH) of requirements] initiated at d 40 of gestation. Ewes were fed individually from d 40, and lambs were removed at parturition. Colostrum was milked from all ewes at 3 h postpartum, and one-half of the ewes (n = 42) were transitioned to a common diet meeting lactation requirements and mechanically milked for 20 d. Colostrum yield was greater (P = 0.02) for HSe ewes than ASe, whereas CON had greater (P < 0.05) colostrum yield than RES and HIH. Colostrum Se (%) was greater (P < 0.01) for HSe than ASe. Colostrum from ewes fed HSe had less (P = 0.03) butterfat (%), but greater (P ≤ 0.05) total butterfat, solids-not-fat, lactose, protein, milk urea N, and Se than ASe. Colostrum from HIH ewes had greater (P ≤ 0.02) solids-not-fat (%) than RES, whereas RES had greater (P ≤ 0.04) butterfat (%) than CON and HIH. Colostrum from ewes fed the CON diet had greater (P = 0.01) total butterfat than HIH. Total solids-not-fat, lactose, and protein were greater (P < 0.05) in colostrum from CON than RES and HIH. Ewes fed HSe had greater (P < 0.01) milk yield (g/d and mL/d) than ASe, and CON and HIH had greater (P < 0.01) yield than RES. Milk protein (%) was greater (P ≤ 0.01) in RES compared with CON or HIH. Ewes fed HSe had greater (P < 0.01) milk Se (µg/g and mg/d) than ASe on each sampling day. Milk from CON and HIH ewes had greater (P < 0.01) total solids-not-fat, lactose, protein, and milk urea N than RES. Total Se was greater (P = 0.02) in milk from ewes fed the CON diet compared with RES. Somatic cell count and total somatic cells were greater (P ≤ 0.05) in milk from CON than RES. A cubic effect of day (P ≥ 0.01) was observed for milk yield (g and mL). Butterfat, solids-not-fat, lactose, milk urea N, and Se concentration responded quadratically (P ≤ 0.01) to day. Protein (%), total butterfat, and total Se, and somatic cells (cells/mL and cells/d) decreased linearly (P < 0.01) with day. Results indicate that gestational nutrition affects colostrum and milk yield and nutrient content, even when lactational nutrient requirements are met.

To examine the impact of corn supplementation of cows on carcass outcomes of their offspring, forty-seven multiparous Angus beef cows carrying male calves were assigned randomly to two dietary treatments. Treatments were control (CON; n=23) receiving ad libitum access to a low quality, forage-based diet (57.54% TDN, 6.4% CP) TMR, and a supplemented group (SUP; n= 24) receiving corn at 0.02% BW (94.5% TDN, 7.64% CP) in addition to ad libitum access to the basal TMR. Dietary treatments started on d 110 of gestation for 22 wks. Following parturition, cows with their offspring were placed on pasture and managed as a single group. Calves were weaned (~159 d of age) and backgrounded for 250 d. Thereafter, the steers were placed in the feedlot, assigned to 4 pens (blocks) based on BW and offered a 57% corn silage/ 38% barley grain-based ration with growth performance measured at 28-day intervals. Pens 1 through 4 were fed for 69, 83, 96, and 137 d, respectively, to reach a final BW of 615 kg (~16 mo of age) and then sent to a commercial abattoir. Steers from SUP and CON cows did not differ in initial BW, final BW, and ADG, during the finishing period (P > 0.05). No significant difference in carcass quality and yield traits, including subprimal cut yields, bone, lean and fat trim, was observed between treatments (P > 0.05). In addition, differences in the frequency distribution of the Canadian quality and yield grades (P > 0.05) were not observed. Warner-Bratzler shear force values tended to be higher in steers from SUP dams than steers from CON dams (P = 0.07). Overall the results indicate that corn supplementation of cows during the mid to late gestation does not affect growth performance and carcass outcomes of their offspring.

Ovine placentomes vary in shape, with type A placentomes being concave, type D convex, and types B and C intermediate in morphology. It has been speculated that as placentomes advance in type they differ in vascularity and nutrient transport capacity. Our objective was to determine cellularity and vascularity measurements, angiogenic factor expression, and arterial vasoactivity within different morphologic types of placentomes. On Day 130 of gestation, placentomes were collected from multiparous ewes (n = 38) and were evaluated for size, cellularity estimates, angiogenic factor mRNA expression, capillary vascularity (capillary size, capillary surface density [CSD], capillary number density [CND], and capillary area density [CAD]), and vasoreactivity to potassium chloride and angiotensin II. The average weight and size of type A and B placentomes were less (P < 0.01) than those of type C and D placentomes. Placentome morphology did not affect (P ≥ 0.24) cotyledonary or caruncular cellularity estim...