Dietary melatonin supplementation alters uteroplacental amino acid flux during intrauterine growth restriction in ewes

Dietary melatonin supplementation during mid- to late-gestation increased umbilical artery blood flow and caused disproportionate fetal growth. This melatonin-induced increase in umbilical artery blood flow may alter nutrient availability to the fetus, which may lead to alterations in fetal size. The objectives of the current experiment were to determine amino acid (AA) and glucose concentrations as well as AA and glucose flux across the uteroplacenta using a mid- to late-gestation model of intrauterine growth restriction supplemented with dietary melatonin as a 2 × 2 factorial design. At day 50 of gestation, 32 ewes were supplemented with 5 mg of melatonin (MEL) or no melatonin (CON) and were allocated to receive 100% (adequate; ADQ) or 60% (restricted; RES) of nutrient requirements. On day 130 of gestation, uterine and umbilical blood flows were determined via Doppler ultrasonography during a non-survival surgery. Blood samples were collected under general anesthesia from the maternal saphenous artery, gravid uterine vein, umbilical artery, and umbilical vein for AA analysis and glucose. Total α-AA concentrations in maternal artery and gravid uterine vein were decreased (P < 0.05) in RES v. ADQ fed ewes. Maternal arterial − venous difference in total α-AA was increased (P ⩽ 0.01) in RES v. ADQ fed ewes, while total uterine α-AA flux was not different (P > 0.40) across all treatment groups. Fetal venous − arterial difference in total α-AA as well as uteroplacental flux of total α-AA were decreased (P < 0.05) in CON-RES v. CON-ADQ, and similar (P > 0.20) in MEL-RES v. CON-ADQ. Maternal concentrations and uterine flux of branched-chain AA (BCAA) were not different across all treatment groups; however, fetal uptake of BCAA was decreased (P < 0.05) in CON-RES v. CON-ADQ, and similar (P > 0.20) in MEL-RES v. CON-ADQ. Uterine uptake of glucose was not different (P ⩾ 0.08) across all treatment groups, while uteroplacental uptake of glucose was increased (P ⩽ 0.05) in RES v. ADQ ewes. In conclusion, maternal nutrient restriction increased maternal arterial − venous difference in total α-AA, while total uterine α-AA flux was unaffected by maternal nutrient restriction. Melatonin supplementation did not impact maternal serum concentrations or uterine flux of glucose or AA; however, melatonin did improve fetal BCAA uptake during maternal nutrient restriction.     

Melatonin supplementation alters uteroplacental hemodynamics and fetal development in an ovine model of intrauterine growth restriction

Using a mid- to late-gestation ovine model of intrauterine growth restriction (IUGR), we examined uteroplacental blood flow and fetal growth during melatonin supplementation as a 2 × 2 factorial design. At day 50 of gestation, 32 ewes were supplemented with 5 mg of melatonin (MEL) or no melatonin (CON) and were allocated to receive 100% [adequate; (ADQ)] or 60% [restricted (RES)] of nutrient requirements until day 130 of gestation. Umbilical artery blood flow was increased from day 60 to day 110 of gestation in MEL vs. CON dams, while umbilical artery blood flow was decreased from day 80 to day 110 of gestation in RES vs. ADQ dams. At day 130 of gestation, uteroplacental hemodynamics, measured under general anesthesia, and fetal growth were evaluated. Uterine artery blood flow was decreased in RES vs. ADQ dams, while melatonin supplementation did not affect uterine artery blood flow. Total placentome weight and placentome number were not different between treatment groups. Fetal weight was decreased by nutrient restriction. Abdominal girth and ponderal index were increased in fetuses from MEL-ADQ dams vs. all other groups. Fetal biparietal distance was decreased in CON-RES vs. CON-ADQ dams, while melatonin supplementation rescued fetal biparietal distance. Fetal kidney length and width were increased by maternal melatonin treatment. Fetal cardiomyocyte area was altered by both maternal melatonin treatment and nutritional plane. In summary, melatonin may negate the consequences of IUGR during specific abnormalities in umbilical blood flow as long as sufficient uterine blood perfusion is maintained during pregnancy.     

The effect of maternal nutrition level during the periconception period on fetal muscle development and plasma hormone concentrations in sheep

The effect of maternal nutrition level during the periconception period on the muscle development of fetus and maternal–fetal plasma hormone concentrations in sheep were examined. Estrus was synchronized in 55 Karayaka ewes and were either fed ad libitum (well-fed, WF, n=23) or 0.5×maintenance (under-fed, UF, n=32) 6 days before and 7 days after mating. Non-pregnant ewes (WF, n=13; UF, n=24) and ewes carrying twins (WF, n=1) and female (WF, n=1; UF, n=3) fetuses were removed from the experiment. The singleton male fetuses from well-fed (n=8) and under-fed (n=5) ewes were collected on day 90 of gestation and placental characteristics, fetal BWs and dimensions, fetal organs and muscles weights were recorded. Maternal (on day 7 after mating) and fetal (on day 90 of pregnancy) blood samples were collected to analyze plasma hormone concentrations. Placental characteristics, BW and dimensions, organs and muscles weights of fetuses were not affected by maternal feed intake during the periconception period. Maternal nutrition level did not affect fiber numbers and the muscle cross-sectional area of the fetal longissimus dorsi (LD), semitendinosus (ST) muscles, but the cross-sectional area of the secondary fibers in the fetal LD and ST muscles from the UF ewes were higher than those from the WF ewes (P<0.05). Also, the ratio of secondary to primary fibers in the ST muscle were tended to be lower in the fetuses from the UF ewes (P=0.07). Maternal nutrition level during the periconception period did not cause any significant changes in fetal plasma insulin and maternal and fetal plasma IGF-I, cortisol, progesterone, free T3 and T4 concentrations. However, maternal cortisol concentrations were lower while insulin concentrations were higher in the WF ewes than those in the UF ewes (P<0.05). These results indicate that the reduced maternal feed intake during the periconception period may alter muscle fiber diameter without affecting fiber types, fetal weights and organ developments and plasma hormone concentrations in the fetus.     

Effects of dietary l-arginine or N-carbamylglutamate supplementation during late gestation of sows on the miR-15b/16, miR-221/222, VEGFA and eNOS expression in umbilical vein

Placental vascular formation and blood flow are crucial for fetal survival, growth and development, and arginine regulates vascular development and function. This study determined the effects of dietary arginine or N-carbamylglutamate (NCG) supplementation during late gestation of sows on the microRNAs, vascular endothelial growth factor A (VEGFA) and endothelial nitric oxide synthase (eNOS) expression in umbilical vein. Twenty-seven landrace?×?large white sows at day (d) 90 of gestation were assigned randomly to three groups and fed the following diets: a control diet and the control diet supplemented with 1.0% l-arginine or 0.10% NCG. Umbilical vein of fetuses with body weight around 2.0?kg (oversized), 1.5?kg (normal) and 0.6?kg (intrauterine growth restriction, IUGR) were obtained immediately after farrowing for miR-15b, miR-16, miR-221, miR-222, VEGFA and eNOS real-time PCR analysis. Compared with the control diets, dietary Arg or NCG supplementation enhanced the reproductive performance of sows, significantly increased (P?<?0.05) plasma arginine and decreased plasma VEGF and eNOS (P?<?0.05). The miR-15b expression in the umbilical vein was higher (P?<?0.05) in the NCG-supplemented group than in the control group. There was a trend in that the miR-222 expression in the umbilical vein of the oversized fetuses was higher (0.05?<?P?<?0.1) than in the normal and IUGR fetuses. The expression of eNOS in both Arg-supplemented and NCG-supplemented group were lower (P?<?0.05) than in the control group. The expression of VEGFA was higher (P?<?0.05) in the NCG-supplemented group than in the Arg-supplemented and the control group. Meanwhile, the expression of VEGFA of the oversized fetuses was higher (P?<?0.05) than the normal and IUGR fetuses. In conclusion, this study demonstrated that dietary Arg or NCG supplementation may affect microRNAs (miR-15b, miR-222) targeting VEGFA and eNOS gene expressions in umbilical vein, so as to regulate the function and volume of the umbilical vein, provide more nutrients and oxygen from the maternal to the fetus tissue for fetal development and survival, and enhance the reproductive performance of sows.     

Mitochondrial biogenesis is decreased in skeletal muscle of pig fetuses exposed to maternal high-energy diets

Mitochondria plays an important role in the regulation of energy homeostasis. Moreover, mitochondrial biogenesis accompanies skeletal myogenesis, and we previously reported that maternal high-energy diet repressed skeletal myogenesis in pig fetuses. Therefore, the aim of this study was to evaluate the effects of moderately increased maternal energy intake on skeletal muscle mitochondrial biogenesis and function of the pig fetuses. Primiparous purebred Large White sows were allocated to a normal energy intake group (NE) as recommended by the National Research Council (NRC) and a high energy intake group (HE, 110% of NRC recommendations). On day 90 of gestation, fetal umbilical vein blood and longissimus (LM) muscle were collected. Results showed that the weight gain of sows fed HE diet was higher than NE sows on day 90 of gestation (P<0.05). Maternal HE diet increased fetal umbilical vein serum triglyceride and insulin concentrations (P<0.05), and tended to increase the homeostasis model assessment index (P=0.08). Furthermore, HE fetuses exhibited increased malondialdehyde concentration (P<0.05), and decreased activities of antioxidative enzymes (P<0.05) and intracellular NAD⁺ level (P<0.05) in LM muscle. These alterations in metabolic traits of HE fetuses were accompanied by reduced mitochondrial DNA amount (P<0.05) and down-regulated messenger RNA expression levels of genes responsible for mitochondrial biogenesis and function (P<0.05). Our results suggest that moderately increased energy supply during gestation decreases mitochondrial biogenesis, function and antioxidative capacity in skeletal muscle of pig fetuses.     

Effect of maternal fatness on fetal steroids and semi-quantitative real-time PCR expression of receptor genes in sheep

Sexual differentiation of the brain occurs between d 30 and 70 in the fetal lamb. The objective of this experiment was to determine if maternal fatness affects fetal steroid production and expression of their receptors which may ultimately alter endocrine systems postnatally. Fetuses were collected from ewes fed at either 100% (Control; n = 5) or 150% (Fat; n = 6) of NRC recommendations from 60 d prior to breeding until collection at 75 d of gestation. Hypothalamic and amygdala neural tissues were collected from twin male/female fetuses. Serum concentrations of testosterone were greater (P < 0.001) in male fetuses compared to female fetuses. Further, male fetuses from Fat ewes had greater (P < 0.05) serum concentrations of testosterone than male fetuses from Control ewes, but differences in testicular steroidogenic enzyme mRNA were not detected (P = 0.18). Quantity of hypothalamic mRNA for estrogen receptor (ER) β tended (P = 0.1) to be influenced by a sex by treatment interaction. Messenger RNA for ER-β was greater in female fetuses than male fetuses from Control ewes (P = 0.05). Although amount of ER-β mRNA did not differ among male fetuses (P = 0.7), amounts tended to be less (P = 0.07) in female fetuses from Fat ewes compared to those from Control ewes, and did not differ (P ≥ 0.8) from male fetuses. Hypothalamic ER-α mRNA tended (P = 0.1) to be less in fetuses from Fat ewes compared to Control fetuses but was not influenced (P = 0.3) by fetal sex or their interaction. Amount of mRNA for hypothalamic progesterone receptor tended (P = 0.06) to be greater in male fetuses than female fetuses and tended to be less (P = 0.06) in fetuses from Fat ewes than in Control fetuses, but did not differ by any sex by treatment interaction (P = 0.6). Hypothalamic RNA for the androgen receptor did not differ by sex, dam nutritional treatment, or the interaction. Likewise, amygdala RNA for the estrogen or androgen receptor did not differ (P ≥ 0.3) by sex, treatment, or their interaction. Dam fatness appears to decrease the expression of progesterone receptor, ER-α, and decrease amount of ER-β in the female fetuses while increasing circulating concentrations of testosterone in male fetuses. Altered expression of hypothalamic receptor genes by the uterine environment may affect adult responses to stress, sexual behavior and/or the pattern of gonadotropin release in response to gonadal steroids.     

Nutritional status of adult ewes during early and mid-pregnancy. 2. Effects of supplementation with selenised yeast on ewe reproduction and offspring performance to weaning

The objective of this study was to determine the effects of selenium (Se) supplementation of mature ewes in the period from day −14 to day 90 post mating on Se status, productivity and viability of ewes and their offspring. Multiparous crossbred ewes (n = 82) were randomly assigned to receive a standard dried grass-based diet (control) or dried grass diet supplemented with 1 g of selenised yeast (Selplex®), providing 0.5 mg Se per ewe per day. After day 90 post mating, all ewes were offered grass-based diets supplemented with a standard multivitamin and mineral mix, up to lambing. Ewes that were fed additional Se had increased (P < 0.001) activity of glutathione peroxidase enzyme (GPx) and increased plasma Se concentrations throughout the treatment period. At lambing, GPx activity of supplemented ewes was higher (P < 0.001) than that of controls. Twenty-four hours after birth, lambs of ewes given Se had higher (P < 0.001) concentration of Se in plasma, greater (P < 0.001) activity of GPx and better (P < 0.01) immune status. Lambs of ewes that received supplementation showed a faster progression to stand than control lambs (P < 0.05), independent of maternal behaviour which was not affected. Supplementation reduced perinatal lamb mortality (0.04 v. 0.17; P < 0.05). However, overall mortality from birth to weaning was unaffected (P > 0.05). Supplemented ewes weaned lambs on average 2 kg heavier than control ewes, due to the higher (P < 0.05) growth rates achieved by their offspring. In conclusion, for ewes with a marginal Se status, an organic source of Se supplemented throughout pregnancy, compared with supplementation only in the last trimester, positively affected measures of lamb viability and survival.     

Hemodynamics of the umbilical artery and conceptus-related measurements in singleton and twin pregnancies in ewes

In sheep, adequate physiological maternal adaptations to twin fetuses are key for their prenatal development. We hypothesized that there is a relationship between maternal circulating steroid hormone concentration, hematocrit, and patterns of conceptus growth and umbilical artery hemodynamics in twin vs singleton pregnancies. Ewes carrying singletons (n = 6) or twins (n = 7) were selected. Hematocrit, progesterone (P₄) and estradiol-17β (E₂) concentrations were analyzed. Blood flow of the umbilical artery (UBF) was assessed through Doppler ultrasonography. Ewes carrying twins had a decreased (p = 0.03) hematocrit. There was a tendency (p = 0.08) for ewes carrying twins to have increased P4 from day 20 to 40. From day 50 to 70, P₄ tended to be increased (p = 0.07) and E₂ was increased (p = 0.01) in ewes carrying twins. From day 90 to 120, ewes carrying twins had greater (p ≤ 0.04) P₄. Ewes carrying twins had increased (p < 0.01) P₄ and tended to have (p = 0.06) increased E₂. From day 60 until 110, placentomes from twins were larger (p ≤ 0.05). On day 50, UBF was greater (p = 0.04; 27.38 vs. 20.95 ± 1.99 ml/min) in twins. It has been suggested that physiological adaptations during early pregnancy can significantly impact fetal development in multiple offspring carrying ewes. Our findings suggest that increased umbilical artery blood flow early in gestation, associated with increased maternal concentrations of P₄ and E₂, and decreased hematocrit (related to plasma volume) could contribute to those adaptations.     

Caffeine supplementation of ewes during lambing may increase lamb survival

Perinatal mortality of lambs is on average 20% of lambs born in extensive Australian grazing systems, constituting a substantial production loss and welfare concern. Hypoxia resulting from prolonged or difficult births contributes to lower rates of lamb survival, and caffeine may reduce the effects of hypoxia. This study evaluated whether oral supplementation of grazing ewes with caffeine could improve lamb survival. Pregnant Merino ewes (n=492) which had been naturally mated to Merino rams in February/March were allocated to three replicates of control (no caffeine) or caffeine treatments. Caffeine was fed daily in troughs in each paddock at a rate of 1.6 g/ewe per day (estimated at 20 mg/kg live weight) from the day before the first lamb was born, for 14 days, with lambing continuing for 6 weeks. Intake was facilitated using 320 g/day per ewe of barley grain with molasses, which was fed to both treatments. The proportion of lambs born alive during the period of supplementation did not differ (P>0.05) between treatments. The proportion mortality of lambs to 1 day of age was lower (P=0.029) in the caffeine (0.01) compared with the control (0.16) treatment for lambs born during the 1^st week of supplementation, but not in later weeks. This difference in mortality for lambs born in the 1^st week of supplementation was maintained to marking age (caffeine 0.09; control 0.30; P=0.027). Extreme weather during the 2^nd week of supplementation may have prevented any reduction in mortality due to caffeine in that week. Feeding caffeine to a naturally lambing flock of grazing ewes may be a highly effective and commercially practical method of increasing lamb survival, but further research is needed to confirm these results, and caffeine be regulated for use.     

A proteomics approach to detect tissue-wide adaptive changes in the pancreas associated with increased pancreatic α-amylase activity in domestic cattle (Bos taurus)

We used a proteomics-based approach to investigate potential regulatory proteins in the pancreas of domestic cattle (Bos taurus) that were associated with differences in pancreatic α-amylase activity. Two groups of 48 and 45 crossbred steers in years 1 and 2, respectively, were fed a high moisture corn-based diet and were ranked according to their pancreatic α-amylase activity. Steers (n = 18) with high, medium, and low α-amylase activity were selected, with 3 for each activity range and 9 for each experimental year, and their proteomic profiles were compared. Pancreatic samples from each animal were fractionated using 2D-HPLC and fractions detected using UV spectrophotometry. Software analysis revealed 119 common protein fractions among the 18 animals, and statistical analysis revealed 10 of these fractions differing (P < 0.10) in abundance between animals from the high and low pancreatic α-amylase activity groups. Five protein fractions identified after tandem mass spectrometry analysis and database searches were found to match proteins with protein-binding, nucleotide/DNA-binding or enzymatic capabilities. Bioinformatics analysis of these fractions revealed porphobilinogen deaminase, a DNA-binding protein, and a putative S1 peptidase that increased in abundance with increasing α-amylase activity; with a putative ATP/GTP binding protein decreasing in abundance with increasing pancreatic α-amylase activity. Changes in these fractions may represent adaptations of the pancreas in domestic cattle that are associated with differences in α-amylase activity.     

The relationship between beta cell activation and SLC30A8/ZnT8 levels of the endocrine pancreas and maternal zinc deficiency in rats

ObjectivesZinc, which is found in high concentrations in the β-cells of the pancreas, is also a critical component for the endocrine functions of the pancreas. SLC30A8/ZnT8 is the carrier protein responsible for the transport of zinc from the cytoplasm to the insulin granules. The aim of this study was to investigate how dietary zinc status affects pancreatic beta cell activation and ZnT8 levels in infant male rats born to zinc-deficient mothers.MethodsThe study was performed on male pups born to mothers fed a zinc-deficient diet. A total of 40 male rats were divided into 4 equal groups. Group 1: In addition to maternal zinc deficiency, this group was fed a zinc-deficient diet. Group 2: In addition to maternal zinc deficiency, this group was fed a standard diet. Group 3: In addition to maternal zinc deficiency, this group was fed a standard diet and received additional zinc supplementation. Group 4: Control group. Pancreas ZnT8 levels were determined by ELISA method and insulin-positive cell ratios in β-cells by immunohistochemistry.ResultsThe highest pancreatic ZnT8 levels and anti-insulin positive cell ratios in the current study were obtained in Group 3 and Group 4. In our study, the lowest pancreatic ZnT8 levels were obtained in Group 1 and Group 2, and the lowest pancreatic anti-insulin positive cell ratios were obtained in Group 1.ConclusionThe results of the present study; in rats fed a zinc-deficient diet after maternal zinc deficiency has been established shows that ZnT8 levels and anti-insulin positive cell ratios in pancreatic tissue, which is significantly suppressed, reach control values with intraperitoneal zinc supplementation.     

Cotyledonary responses to maternal selenium and dietary restriction may influence alterations in fetal weight and fetal liver glycogen in sheep

To examine the effects of maternal supranutritional selenium (Se) and nutrient restriction during mid and late gestation on placental characteristics and fetal liver glycogen, ewes received either adequate Se (ASe) or high Se (HSe) prior to breeding. On d 64 of gestation, ASe and HSe ewes remained at 100% of requirements (controls; CON) or were restricted (RES; 60% of requirements). On d 135 of gestation, fetal weight (P ≤ 0.08) was greatest in both HSe and CON ewes. Placentome number, mass, and caruncular and cotyledonary weight were not different (P ≥ 0.17) among treatments. Fetal mass:placental mass ratio was less (P = 0.06) in RES compared to CON ewes. Compared to ASe, HSe exhibited increased (P ≤ 0.08) cellular proliferation and DNA concentration and decreased (P = 0.07) cellular size in cotyledonary tissue. Nutritional restriction decreased (P ≤ 0.08) cotyledonary protein concentration and cellular size. VEGF receptor 1 (Flt) mRNA in cotyledonary tissue was greater in HSe compared with ASe ewes (P = 0.06) and in RES compared with CON ewes (P = 0.08). There was no effect of diet on caruncular growth variables (P ≥ 0.13) or on placental vascularity (P ≥ 0.11). Progesterone was greater (P ≤ 0.08) in ASe–RES ewes compared to all groups at d 90 and ASe–CON and HSe–CON at d 104. Although fetal glucose and cortisol concentrations were not affected by diet, fetal liver glycogen was greater (P = 0.04) in ASe–RES compared to ASe–CON and HSe–RES ewes with HSe–CON being intermediate. Both Se and nutritional plane may impact placental function and fetal growth, as fetal weight and liver glycogen are altered despite similar placental vascularity measurements.     

Growth,meat and feed efficiency traits of lambs born to ewes submitted to energy restriction during mid-gestation

The objective of this study was to evaluate the effects of the energy restriction of gestation of adult ewes from day 45 to day 115 on lamb live performance parameters, carcass and meat traits. In experiment I, dietary energy was restricted at 70% of the metabolizable energy (ME) requirements, after which ewes were re-fed ad libitum until lambing. In experiment II, dietary energy was restricted at 60% of the ME requirements, and ewes were re-fed to ME requirements until lambing. All ewes grazed together from the end of the restriction periods to weaning. Lambs were weaned and lot fed until slaughter. Feed intake, weight gain and feed efficiency were recorded, and body fat thickness and ribeye area (REA) were measured in the longissimus thoracis muscle. After slaughter, carcass weight and yield, fat depth, carcass and leg length, and frenched rack and leg weights and yields were determined. Muscle fiber type composition, Warner-Bratzler shear force, pH and color were determined in the longissimus lumborum muscle. In experiment I, energy restriction followed by ad libitum feeding affected lamb birth weight (P<0.05); however, no effects (P>0.05) were observed on later BW, REA, BF or carcass traits. Lambs born to non-restricted-fed ewes had higher (P<0.05) weight and yield of the frenched rack cut and their meat tended (P=0.11) to be tender compared with that of lambs from restricted ewes. The percentage of oxidative muscle fibers was lower for lambs born to non-restricted ewes (P<0.05); however, no effects of ewe treatment were observed on other muscle fiber types. For experiment II, energy restriction followed by ME requirements feeding, affected (P<0.01) pre-weaning live weight gain, weaning and final weights. Lambs from restricted ewes had higher (P<0.05) feed intake as % of leg weight and a trend to be less efficient (P=0.16) than lambs from unrestricted dams. Ribeye area and BF were not influenced by treatment. Treatment significantly affected slaughter weight, but had no effects on carcass yield and traits or on meat traits. The results obtained in both experiments indicate submitting ewes to energy restriction during gestation affects the performance of their progeny but the final outcome would depend on the ewe’s re-feeding level during late gestation and the capacity of the offspring to compensate the in utero restriction after birth.     

Leucine regulates α-amylase and trypsin synthesis in dairy calf pancreatic tissue in vitro via the mammalian target of rapamycin signalling pathway

Starch digestion in the small intestines of the dairy cow is low, to a large extent, due to a shortage of syntheses of α-amylase. One strategy to improve the situation is to enhance the synthesis of α-amylase. The mammalian target of rapamycin (mTOR) signalling pathway, which acts as a central regulator of protein synthesis, can be activated by leucine. Our objectives were to investigate the effects of leucine on the mTOR signalling pathway and to define the associations between these signalling activities and the synthesis of pancreatic enzymes using an in vitro model of cultured Holstein dairy calf pancreatic tissue. The pancreatic tissue was incubated in culture medium containing l-leucine for 3 h, and samples were collected hourly, with the control being included but not containing l-leucine. The leucine supplementation increased α-amylase and trypsin activities and the messenger RNA expression of their coding genes (P <0.05), and it enhanced the mTOR synthesis and the phosphorylation of mTOR, ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E-binding protein 1 (P <0.05). In addition, rapamycin inhibited the mTOR signal pathway factors during leucine treatment. In sum, the leucine regulates α-amylase and trypsin synthesis in dairy calves through the regulation of the mTOR signal pathways.     

Multiple matings modify the estrous length,the moment of ovulation,and the estradiol and LH patterns in ewes

In several species, mating reduces the estrous length and advances ovulation. The aim of this study was to determine if multiple matings reduces the estrous length and modifies the moment of ovulation, as well as the estradiol and LH patterns in ewes. The estrous cycle of Corriedale ewes was synchronized, and the onset of receptivity was monitored every 3 h with rams, avoiding mating. At the estrous onset, ewes were assigned to two experimental groups (n=10 each): 1) estrous was monitored every 3 h with a ram avoiding mating (group CON), and 2) a ram was allowed to mate and ejaculate once every 3 h (group MAT). The ovaries were scanned with transrectal ultrasonography and blood samples were collected for measuring 17β-estradiol and LH concentrations every 3 h until ovulation. Estrus was shorter in MAT than CON ewes (24.7 ± 1.5 h vs. 30.4 ± 1.5 h, respectively; P=0.02); the proportion of animals that ovulated before the end of estrus was greater in CON ewes: (9/10 vs. 3/10, P=0.009). The area under the LH curve (AUC) was greater in MAT than CON ewes (36.1 ± 3.5 ng.h^-1.mL^-1 vs 24.9 ± 3.5 ng.h^-1.mL^-1 P=0.03). However, MAT ewes had a lower 17β-estradiol AUC than CON ewes (41.0 ± 4.9 pg.h^-1.mL^-1 vs 59.4 ± 4.9 pg.h^-1.mL^-1 P=0.01). Mating reduced the estrous length, induced a greater secretion of LH but less total 17β-estradiol secreted and, additionally, ovulation occurred more frequently after the end of estrus in mated ewes.     

Effect of maternal pinealectomy and reverse photoperiod on the circadian melatonin rhythm in the sheep and fetus during the last trimester of pregnancy

The present study tested the hypothesis that the nocturnal melatonin rhythm in the fetal sheep results from transfer across the placenta of melatonin from maternal circulation. Pregnant ewes were exposed to an artificial reverse photoperiod at about 100 days gestation (n = 6; lights on 10 h, 2200-0800 h PST). This treatment tested for entrainment in the ewe and its fetus of the 24-h pattern of melatonin production from the pineal gland. Other ewes were pinealectomized at 55 days post-breeding (n = 6), and similarly treated. Catheters were implanted and blood samples were collected between 117 and 142 days gestation at two 48-h periods, about every 0.5-4 h, to assess the pattern of melatonin in maternal and fetal circulations. In pineal-intact ewes and their fetuses, melatonin rhythms conformed to the reverse photoperiod, i.e. plasma melatonin concentrations were relatively low during the light period and significantly increased for the duration of darkness. In contrast, maternal pinealectomy abolished the melatonin rhythms in both the ewe and fetus; melatonin concentrations remained at or below the limits of detection. Pineal-intact sheep gave birth about 139 +/- 2 days (mean +/- SE, n = 4) at 1915 +/- 0.7 h and pinealectomized ewes (n = 5 of 6) lambed at 149 +/- 2 days at 0424 +/- 0.5 h. Finally, in lambs (n = 3) born to pinealectomized ewes, typical melatonin rhythms were present within the first week of life. The findings indicate that the maternal pineal gland is responsible for the 24-h pattern of melatonin in the ewe and its fetus during the last trimester of pregnancy.     

Orally Administered Melatonin Prevents Lipopolysaccharide-Induced Neural Tube Defects in Mice

Lipopolysaccharide (LPS) has been associated with adverse pregnant outcomes, including fetal demise, intra-uterine growth restriction (IUGR), neural tube defects (NTDs) and preterm delivery in rodent animals. Previous studies demonstrated that melatonin protected against LPS-induced fetal demise, IUGR and preterm delivery. The aim of the present study was to investigate the effects of melatonin on LPS-induced NTDs. All pregnant mice except controls were intraperitoneally injected with LPS (25 µg/kg) daily from gestational day (GD)8 to GD12. Some pregnant mice were orally administered with melatonin (MT, 50 mg/kg) before each LPS injection. A five-day LPS injection resulted in 27.5% of fetuses with anencephaly, exencephaly or encephalomeningocele. Additional experiment showed that maternal LPS exposure significantly down-regulated placental proton-coupled folate transporter (pcft) and disturbed folate transport from maternal circulation through the placentas into the fetus. Interestingly, melatonin significantly attenuated LPS-induced down-regulation of placental pcft. Moreover, melatonin markedly improved the transport of folate from maternal circulation through the placentas into the fetus. Correspondingly, orally administered melatonin reduced the incidence of LPS-induced anencephaly, exencephaly or encephalomeningocele. Taken together, these results suggest that orally administered melatonin prevents LPS-induced NTDs through alleviating LPS-induced disturbance of folate transport from maternal circulation through the placenta into the fetus.     

Supplementation of Merino ewes with vitamin E plus selenium increases α-tocopherol and selenium concentrations in plasma of the lamb but does not improve their immune function

Vitamin E and selenium have been reported to improve immune function across a range of species. Ewes lambing on poor-quality dry pasture in autumn in Western Australia are at risk of being deficient in vitamin E and selenium at lambing thus predisposing their lambs to deficiencies and increasing the risk of infection and disease. This study tested the hypotheses that (i) supplementation of autumn-lambing ewes with vitamin E plus selenium in late gestation will increase the concentrations of vitamin E and selenium in plasma in the ewe and lamb and (ii) that the increased concentrations of vitamin E and selenium in plasma in the lambs will improve their innate and adaptive immune responses and thus survival. Pregnant Merino ewes were divided into a control group (n=58) which received no supplementation or a group supplemented with vitamin E plus selenium (n=55). On days 111, 125 and 140 of pregnancy ewes in the vitamin E plus selenium group were given 4 g all-rac-α-tocopherol acetate orally. On day 111 the ewes were also given 60 mg of selenium as barium selenate by subcutaneous injection. The concentrations of α-tocopherol and selenium were measured in ewes and/or lambs from day 111 of pregnancy to 14 weeks of age±10 days (weaning). Immune function of the lamb was assessed by analysing the numbers and phagocytic capacities of monocytes and polymorphonuclear leucocytes and plasma IgG and anti-tetanus toxoid antibody concentrations between birth and 14 weeks of age±10 days. Maternal supplementation with vitamin E plus selenium increased the concentration of α-tocopherol in plasma (1.13 v. 0.67 mg/l; P<0.001) and selenium in whole blood (0.12 v. 0.07 mg/l; P<0.01) of the ewes at lambing compared with controls. Supplementation also increased the concentration of α-tocopherol (0.14 v. 0.08 mg/l; P<0.001) and selenium (0.08 v. 0.05 mg/l; P<0.01) in lambs at birth compared with controls. There was no significant effect of supplementation on immune function or survival in the lambs.     

Effect of hormonal status and metabolic changes of restricted ewes during late pregnancy on their fetal growth and development

This study investigated the effects of hormonal status and metabolic changes of restricted ewes during late pregnancy on the ovine fetus growth and development. One hundred Mongolian ewes, synchronized for oestrus and mated, were divided into three groups and offered 0.175 MJME·kgw^−0.75·d⁻¹ (Restricted Group 1, RG1), 0.33 MJME·kgw^−0.75·d⁻¹ (Restricted Group 2, RG2) and ad libitum access to feed (Control Group, CG) during their late pregnancy respectively. The results suggested that with the supply of exogenous energy decreasing during late pregnancy, maternal body weight and net body weight loss in RG2 and RG1 were lower than those of CG (Ps0.01). The insulin and IGF-1 concentrations of ewes in RG2 and RG1 tended to be lower than those of CG (P>0.05), but the GH concentrations in RG2 and RG1 were enhanced and there was significant difference between RG1 and CG on d 120 of gestation (P<0.05). The glucose concentration of ewes in RG2 and RG1 was decreased throughout the feed restriction period, and the differences were observed between RG1 and CG on d 120 of gestation (P<0.05). In addition, the nonesterified fatty acid (NEFA) and total amino acid (TAA) concentrations of ewes in RG2 tended to increase, but there was no significant difference (P>0.05). However, the NEFA and FAA concentrations of ewes in RG1 were reduced from d 90 to d 120 of gestation, then enhanced from d 120 to d 140 of gestation. During the late pregnancy, with the supply of nutrition decreasing, the negatively physiological and biochemical maternal reactions to restriction became worse, which significantly reduced the average lamb birth weight and daily growth rate of fetus in RG2 (P<0.05) and RG1 (P<0.01).     

Reproductive response and LH secretion in ewes treated with melatonin implants and induced to ovulate with the ram effect

Two experiments were conducted to examine the effects of treating seasonally anoestrous ewes with melatonin before ram introduction on reproductive response, and on LH secretion in anoestrous ewes induced to ovulate by rams.In Experiment 1, a total of 667 ewes from three flocks involving Merino (Flock 1, N = 149), Merino entrefino (Flock 2, N = 325) and Rasa Aragonesa (Flock 3, N = 203) breeds were used. Within each flock, ewes isolated from rams since the previous lambing were assigned at random to receive melatonin implants of Regulin (75, 175 and 105 in Merino, Merino entrefino and Rasa Aragonesa flocks, respectively) or to serve as untreated controls (74 in Merino, 150 in Merino entrefino and 98 in Rasa Aragonesa flocks). Fertile rams were introduced into all flocks 5 weeks after implantation in March (Flocks 1 and 2) or April (Flock 3), and remained with the ewes for a 50 day mating period. Percentage of ewes with luteal activity at ram introduction did not differ between melatonin treated and control ewes in any flock. There were no significant differences in either the mean interval from ram introduction to lambing or the distribution of lambing. Implantation with melatonin resulted in an improvement of prolificacy in all three flocks, although this only reached statistical significance in the Merino flock (1.15 vs. 1.03 in treated and control ewes, respectively, P < 0.05). Fertility was increased significantly (P < 0.05) in the Merino entrefino flock (64.5% in treated vs. 51.3% in control ewes).In Experiment 2, two trials were undertaken utilizing a total of 63 ewes. Trial 1 involved 24 mature Manchega ewes and Trial 2 involved 39 Merino ewe lambs. Half of the animals in each trial received a Regulin implant on 28 February (Trial 1) or 12 March (Trial 2) and the remaining half acted as controls. Rams were introduced 5 weeks after implantation and remained with the ewes for a 25 day period. In both trials, anoestrous ewes at ram introduction were bled at 20 min intervals for 3 h before and 5 h after ram introduction and then at 3 h intervals over the next 24 h for assessment of plasma concentrations of LH. Secretion of LH before or following introduction of rams was not affected by melatonin. Both treated and control anoestrous ewes in each trial responded to introduction of rams with an increase in the frequency of the LH pulses (P < 0.05), but no significant changes were detected in pulse amplitude or mean levels of LH. A preovulatory surge of LH was detected between 8 and 26 h after ram introduction, but neither mean interval from ram introduction to the peak of LH surge, nor the magnitude of the LH peak, was influenced by melatonin treatment.Results from this study show that: (1) melatonin implants administered during early seasonal anoestrus have the potential to improve reproductive performance in Spanish breeds of sheep, but the response is conditioned by breed, management system and environmental factors; (2) melatonin did not modify the secretion of LH in anoestrous ewes induced to ovulate by the ram effect under our experimental conditions.