BOARD-INVITED REVIEW: Intrauterine growth retardation: Implications for the animal sciences1

Effects of limited and excess protein intakes of pregnant gilts on carcass quality and cellular properties of skeletal muscle and subcutaneous adipose tissue in fattening pigs

The aim of this study was to investigate whether dietary protein intake of gilts during gestation below (50%) or above (250%) recommendations affects body composition, carcass and meat quality, and properties of skeletal muscle and subcutaneous adipose tissue (SCAT) in offspring at d 83 and 188 of age. German Landrace gilts were fed isoenergetic gestation diets (~13.7 MJ of ME/kg) containing a low (LP, 6.5%; n = 18), an adequate (AP, 12.1%; n = 20), or a high (HP, 30%; n = 16) protein content from mating until farrowing. Within 48 h of birth, offspring were cross-fostered to sows fed a standard diet. On d 83 of age, no effects of the LP diet on BW and body composition were detected, whereas HP pigs showed a slight growth delay (P = 0.06) associated with increased relative weights of small intestine (P < 0.01) and brain (P = 0.08), and reduced relative thymus weight (P < 0.01). On d 188 of age, BW was not different among the dietary groups. However, the carcass of LP pigs contained less (P = 0.01) lean and more (P = 0.07) fat compared with AP and HP pigs, which was only pronounced in pigs originating from large litters (P < 0.05). Like skeletal muscles (P = 0.06), the heart muscle weighed less (P = 0.02) in LP than AP pigs. Compared with AP pigs, LP pigs exhibited a fewer (P = 0.09) total number of myofibers in semitendinosus muscle plus LM both at d 83 and 188 of age, whereas total muscular DNA was less (P = 0.02) at d 188 only. The mRNA abundance of IGF2 measured on d 188 was reduced in SCAT (P = 0.03) and LM (P = 0.07) of LP compared with AP pigs. No changes in muscular fiber type frequency, capillary density, or creatine kinase activity, as well as SCAT adipocyte size and number, were observed at either stages of age. Meat quality characteristics remained unchanged at d 83, whereas Warner-Bratzler shear force value in LM was decreased (P = 0.03) in LP compared with AP pigs on d 188 of age. The results suggest that the maternal LP diet impairs prenatal myofiber formation, reduces the potential of postnatal lean growth related to reduced IGF2 mRNA expression and myonuclear accumulation, and consequently changes carcass quality toward reduced lean proportion and improved tenderness at market weight. In contrast, except for a slight transient growth delay, excess dietary protein during gestation seems to have little effect on the fetal programming of postnatal muscle and adipose tissue phenotype of the progeny.

Somatic cytochrome c (CYCS) gene expression and promoter-specific DNA methylation in a porcine model of prenatal exposure to maternal dietary protein excess and restriction

There is growing evidence that maternal nutrition during gestation has an important effect on offspring development as well as on their gene expression with long-term effects on the metabolic state. A potential mechanism forming long-lasting gene expression patterns is DNA methylation of cytosine in CpG dinucleotides within the promoter region of distinct genes. There has been special focus on mitochondrial dysfunction by prenatal malnourishment over the recent years. To this end, we investigated the gene expression of somatic cytochrome c (CYCS), an important member of the respiratory chain, in a porcine model of gestational protein over- and undersupply at 94 d post-conception and 1, 28 and 188 d of age, and analysed the association with the DNA methylation status within the CYCS promoter. Gene expression on day 1 post natum showed a significant increase in the low protein (LP) group (P = 0·0005) and a slight increase in the high protein (HP) group (P = 0·079) compared with the control (CO) group in the liver. The mean of the methylation level over forty-seven CpG sites from nucleotide (nt) − 417 to − 10 was significantly decreased in the LP (P = 0·007) and HP (P = 0·009) groups compared with that in the CO group. Excess and restricted protein supply during pregnancy led to hypomethylation of a number of CpG sites in the CYCS promoter, including those representing putative transcription factor-binding sites, associated with elevated expression levels. However, the impact of the low-protein gestation diet is more pronounced, indicating that the offspring could better adapt to excess rather than restricted protein supply.

Efeito da adição de agentes tróficos na dieta de leitões desmamados sobre a estrutura e ultraestrutura do intestino delgado e sobre o desempenho

Foram estudados os efeitos da glutamina, dos ácidos graxos poli-insaturados e da parede celular de levedura (PCL) sobre a estrutura e ultraestrutura do intestino delgado e o desempenho de leitões. Foram utilizados 45 leitões, desmamados aos 21 dias de idade, para testar os seguintes tratamentos: T1 - dieta basal; T2 - dieta basal + 1% de glutamina; T3 - dieta basal + 0,2% de PCL; T4 - dieta basal + 5% de óleo de peixe. Nos dias sete e 14 pós-desmame, foram abatidos cinco leitões de cada tratamento. Os aditivos testados não alteraram a altura e a densidade dos vilos nem a profundidade das criptas do intestino delgado. Foi observado efeito de idade, mostrando redução na altura e na densidade dos vilos e na profundidade das criptas após o desmame. No duodeno e jejuno, foram observados maiores valores de relação vilo:cripta, que aumentaram com a idade pós-desmame. Ocorreram redução da altura dos microvilos do duodeno aos sete dias e aumento da largura dos microvilos do jejuno aos 14 dias pós-desmame. A área de superfície apical dos enterócitos não foi alterada pelos fatores estudados. Os aditivos estudados não foram eficientes em prevenir a atrofia da mucosa intestinal do jejuno, ao não interferir na sua ultraestrutura. Os aditivos incluídos na dieta não influenciaram o desempenho dos leitões no pós-desmame.

A high protein diet during pregnancy affects hepatic gene expression of energy sensing pathways along ontogenesis in a porcine model

In rodent models and in humans the impact of gestational diets on the offspring's phenotype was shown experimentally and epidemiologically. The underlying programming of fetal development was shown to be associated with an increased risk of degenerative diseases in adulthood, including the metabolic syndrome. There are clues that diet-dependent modifications of the metabolism during fetal life can persist until adulthood. This leads to the hypothesis that the offspring's transcriptomes show short-term and long-term changes depending on the maternal diet. To this end pregnant German landrace gilts were fed either a high protein diet (HP, 30% CP) or an adequate protein diet (AP, 12% CP) throughout pregnancy. Hepatic transcriptome profiles of the offspring were analyzed at prenatal (94 dpc) and postnatal stages (1, 28, 188 dpn). Depending on the gestational dietary exposure, mRNA expression levels of genes related to energy metabolism, N-metabolism, growth factor signaling pathways, lipid metabolism, nucleic acid metabolism and stress/immune response were affected either in a short-term or in a long-term manner. Gene expression profiles at fetal stage 94 dpc were almost unchanged between the diets. The gestational HP diet affected the hepatic expression profiles at prenatal and postnatal stages. The effects encompassed a modulation of the genome in terms of an altered responsiveness of energy and nutrient sensing pathways. Differential expression of genes related to energy production and nutrient utilization contribute to the maintenance of development and growth performance within physiological norms, however the modulation of these pathways may be accompanied by a predisposition for metabolic disturbances up to adult stages.

Developmental origin of chronic diseases: toxicological implication

Human epidemiological and experimental animal studies show that suboptimal environments in fetal and neonatal life exerts a profound influence on physiological function and risk of disease in adult life. The molecular, cellular, metabolic, endocrine and physiological adaptations to intrauterine nutritional conditions result in permanent alterations of cellular proliferation and differentiation of tissues and organ systems, which in turn can manifest by pathological consequences or increased vulnerability to chronic diseases in adulthood. Intrauterine growth restriction (IUGR) due to intrauterine development derangements is considered the important factor in development of such diseases as essential hypertension, diabetes mellitus, ischemic diseases of the heart, osteoporosis, respiratory, neuropsychiatric and immune system diseases.

An early life exposures to dietary and environmental exposures can have a important effect on epigenetic code, resulting in diseases developed later in life. The concept of the "developmental programming" and Developmental Origins of Adult Diseases (DOHaD) has become well accepted because of the compelling animal studies that have precisely defined the outcomes of specific exposures.

The environmental pollullutants and other chemical toxicants may influence crucial cellular functions during critical periods of fetal development and permanently alter the structure or function of specific organ systems. Developmental epigenetics is believed to establish "adaptive" phenotypes to meet the demands of the later-life environment. Resulting phenotypes that match predicted later-life demands will promote health, while a high degree of mismatch will impede adaptability to later-life challenges and elevate disease risk. The rapid introduction of synthetic chemicals, environmental pollutants and medical interventions, may result in conflict with the programmed adaptive changes made during early development, and explain the alarming increases in some diseases.

Genome Scan for Parent-of-Origin QTL Effects on Bovine Growth and Carcass Traits

Parent-of-origin effects (POE) such as genomic imprinting influence growth and body composition in livestock, rodents, and humans. Here, we report the results of a genome scan to detect quantitative trait loci (QTL) with POE on growth and carcass traits in Angus × Brahman cattle crossbreds. We identified 24 POE–QTL on 15 Bos taurus autosomes (BTAs) of which six were significant at 5% genome-wide (GW) level and 18 at the 5% chromosome-wide (CW) significance level. Six QTL were paternally expressed while 15 were maternally expressed. Three QTL influencing post-weaning growth map to the proximal end of BTA2 (linkage region of 0–9 cM; genomic region of 5.0–10.8 Mb), for which only one imprinted ortholog is known so far in the human and mouse genomes, and therefore may potentially represent a novel imprinted region. The detected QTL individually explained 1.4 ∼ 5.1% of each trait’s phenotypic variance. Comparative in silico analysis of bovine genomic locations show that 32 out of 1,442 known mammalian imprinted genes from human and mouse homologs map to the identified QTL regions. Although several of the 32 genes have been associated with quantitative traits in cattle, only two (GNAS and PEG3) have experimental proof of being imprinted in cattle. These results lend additional support to recent reports that POE on quantitative traits in mammals may be more common than previously thought, and strengthen the need to identify and experimentally validate cattle orthologs of imprinted genes so as to investigate their effects on quantitative traits.

Optimal nutritional intake for fetal growth

The regular nutritional intake of an expectant mother clearly affects the weight development of the fetus. Assuming the growth of the fetus follows a deterministic growth law, like a logistic equation, albeit dependent on the nutritional intake, the ideal solution is usually determined by the birth-weight being pre-assigned, for example, as a percentage of the mother's average weight. This problem can then be specified as an optimal control problem with the daily intake as the control, which appears in a Michaelis-Menten relationship, for which there are well-developed procedures to follow. The best solution is determined by requiring minimum total intake under which the preassigned birth weight is reached. The algorithm has been generalized to the case where the fetal weight depends in a detailed way on the cumulative intake, suitably discounted according to the history. The optimality system is derived and then solved numerically using an iterative method for the specific values of parameter. The procedure is generic and can be adapted to any growth law and any parameterisation obtained by the detailed physiology.

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.

Intrauterine growth restriction alters the metabonome of the serum and jejunum in piglets

Intrauterine growth restriction (IUGR) is not only an underlying factor for stunted postnatal growth and newborn deaths, but also associated with disease prevalence, such as hypertension and diabetes, in both adult humans and animals. To investigate the metabolic status of IUGR, the differences in serum and jejunal tissue metabonome were examined in IUGR and normal weight 21 day old piglets. IUGR piglets had a significantly lower birth weight (785 ± 42 g vs. 1451 ± 124 g), weaned weight (3053 ± 375 g vs. 6489 ± 545 g) and average daily gain (108 ± 16 g vs. 240 ± 21 g) than normal weight piglets (p < 0.05). IUGR piglets also had a shorter villus height and smaller villus height to crypt depth ratio (p < 0.05) in jejunum. An NMR-based metabonomic study found that serum levels of glycoprotein, albumin and threonine were higher in IUGR than in normal weight piglets, while serum levels of HDL, lipids, unsaturated lipids, glycerophosphorylcholine, myo-inositol, citrate, glutamine and tyrosine were lower in IUGR piglets (p < 0.05). In addition, marked changes in jejunal metabolites, including elevated levels of lipids and unsaturated lipids, and decreased levels of valine, alanine, glutamine, glutamate, choline, glycerophosphorylcholine, trimethylamine-N-oxide, scyllo-inositol, lactate, creatine, glucose, galactose, phenylalanine, tyrosine, glutathione, inosine and taurine were observed in IUGR piglets (p < 0.05). These novel findings indicate that IUGR piglets have a distinctive metabolic status compared to normal weight piglets, including changes in lipogenesis, lipid oxidation, energy supply and utilization, amino acid and protein metabolism, and antioxidant ability; these changes could contribute to impaired growth and jejunal function.

Limited and excess protein intake of pregnant gilts differently affects body composition and cellularity of skeletal muscle and subcutaneous adipose tissue of newborn and weanling piglets

AIM

This study investigated whether dietary protein intake less (50%) or greater (250%) than requirements throughout gestation differently affects offspring body composition and cellular properties of skeletal muscle and subcutaneous adipose tissue (SCAT).

METHODS

Primiparous gilts were fed iso-energetic diets containing adequate (22 AP), high (21 HP), or low (19 LP) protein contents. Newborn (n = 166) and weanling piglets cross-fostered to sows fed a standard diet (day 28; n = 83) were examined by morphological, biochemical, histological, and molecular analyses of the body, SCAT, and semitendinosus, longissimus, biceps femoris muscles.

RESULTS

Lowered birth weight (BW) in response to the HP and LP diets (p < 0.01) resulted from decreases in all body constituents in LP, and mainly from reduced body fat in HP piglets (p < 0.05). In the light BW class within litters, HP piglets exhibited a greater percentage of muscle tissue (p < 0.05) than LP piglets. Less SCAT mass in HP and LP piglets resulted from reduced (p < 0.05) number, but not the size of adipocytes. The LP diet adversely affected myogenesis and muscular differentiation derived from less (p < 0.01) primary and secondary myofibers, lower creatine kinase activity (p < 0.05), less IGF2 mRNA (p < 0.10), and greater expression of the embryonic myosin heavy chain isoform (p < 0.01). Catch-up growth of LP but not HP pigs until day 28 increased body fat (p = 0.01). Despite compensated muscle growth in LP piglets, the deficit in myofiber number remained.

CONCLUSION

Poor intrauterine environment by limited and excess protein supply retards fetal growth, but only limited protein supply impairs myogenesis, persistently restricts muscle growth potential, and favors obesity at infancy.

Parenteral administration of L-arginine enhances fetal survival and growth in sheep carrying multiple fetuses

The frequency of multiple fetuses has increased in human pregnancies due to assisted reproductive technologies. This translates into a greater proportion of premature and low-birth weight infants in the United States and worldwide. In addition, improvements in sheep breeding have resulted in new breeds with increased litter size but reduced fetal survival and birth weight. Currently, there are no treatments for preventing fetal growth restriction in humans or sheep (an established model for studying human fetal physiology) carrying multiple fetuses. In this work, Booroola Rambouillet ewes (FecB+/-) with 2-4 fetuses were fed a diet providing 100% of NRC-recommended nutrient requirements. Between d 100 and 121 of gestation, ewes received an i.v. bolus injection of either saline solution or 345 μmol arginine-HCl/kg body weight 3 times daily. The arginine treatment reduced (P < 0.05) the percentage of lambs born dead by 23% while increasing (P = 0.05) the percentage of lambs born alive by 59%. The i.v. administration of arginine enhanced (P < 0.05) the birth weights of quadruplets by 23% without affecting maternal body weight. The improved pregnancy outcome was associated with an increase in maternal plasma concentrations of arginine, ornithine, cysteine, and proline, as well as a decrease in circulating levels of ammonia and β-hydroxybutyrate. These novel results indicate that parenteral administration of arginine to prolific ewes ameliorated fetal mortality and growth retardation. Our findings provide support for experiments to assess the clinical use of arginine to enhance fetal growth and survival in women gestating multiple fetuses.

Administration of thyroxine affects the morphometric parameters and VEGF expression in the uterus and placenta and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation

The aim of this study was to evaluate the effects of thyroxine administration on morphometric parameters, expression of vascular endothelial growth factor (VEGF) and vascularization in the uterus and placenta and reproductive parameters in gilts at 70 days of gestation. At 150 days of age, i.e., before first heat, 20 gilts were randomly divided into two experimental groups: treated (n=10) and control (n=10). The treated group received a daily dose of 400 μg of L-thyroxine (T(4)) in their diet until slaughter and the control group received only typical meals. Before artificial insemination, blood was collected to determine plasma total T(4). The gilts were inseminated in the second oestrus and slaughtered at 70 days of gestation. The foetal thyroid follicular epithelium height, number, size and weight of foetuses; foetal myogenesis, corpora lutea number, embryonic mortality rate, uterine weight, placental weight and placental fluid volume were measured. Histomorphometric and immunohistochemical analysis of uterus and placenta were determined. The averages of all variables were compared by the Student's t-test. The gilts treated with thyroxine showed significant increase of plasma total T(4). At 70 days of gestation, the heights of the trophoblastic epithelium, endometrial epithelium and endometrial gland epithelium were significantly higher in the group treated with T(4). The expression of cytoplasmatic and nuclear VEGF in trophoblastic cells and the number of blood vessels per field in endometrial stroma were significantly higher in the gilts treated with T(4). No other significant differences between groups were obtained with respect to other parameters (p>0.05). We conclude that oral administration of T(4) up to 70 days of pregnancy in gilts affects the morphometric parameters, the expression of placental VEGF and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation.

Proline and hydroxyproline metabolism: implications for animal and human nutrition

Proline plays important roles in protein synthesis and structure, metabolism (particularly the synthesis of arginine, polyamines, and glutamate via pyrroline-5-carboxylate), and nutrition, as well as wound healing, antioxidative reactions, and immune responses. On a per-gram basis, proline plus hydroxyproline are most abundant in collagen and milk proteins, and requirements of proline for whole-body protein synthesis are the greatest among all amino acids. Therefore, physiological needs for proline are particularly high during the life cycle. While most mammals (including humans and pigs) can synthesize proline from arginine and glutamine/glutamate, rates of endogenous synthesis are inadequate for neonates, birds, and fish. Thus, work with young pigs (a widely used animal model for studying infant nutrition) has shown that supplementing 0.0, 0.35, 0.7, 1.05, 1.4, and 2.1% proline to a proline-free chemically defined diet containing 0.48% arginine and 2% glutamate dose dependently improved daily growth rate and feed efficiency while reducing concentrations of urea in plasma. Additionally, maximal growth performance of chickens depended on at least 0.8% proline in the diet. Likewise, dietary supplementation with 0.07, 0.14, and 0.28% hydroxyproline (a metabolite of proline) to a plant protein-based diet enhanced weight gains of salmon. Based on its regulatory roles in cellular biochemistry, proline can be considered as a functional amino acid for mammalian, avian, and aquatic species. Further research is warranted to develop effective strategies of dietary supplementation with proline or hydroxyproline to benefit health, growth, and development of animals and humans.

Composition of amino acids in feed ingredients for animal diets

Dietary amino acids (AA) are crucial for animal growth, development, reproduction, lactation, and health. However, there is a scarcity of information regarding complete composition of "nutritionally nonessential AA" (NEAA; those AA which can be synthesized by animals) in diets. To provide a much-needed database, we quantified NEAA (including glutamate, glutamine, aspartate, and asparagine) in feed ingredients for comparison with "nutritionally essential AA" (EAA; those AA whose carbon skeletons cannot be formed by animals). Except for gelatin and feather meal, animal and plant ingredients contained high percentages of glutamate plus glutamine, branched-chain AA, and aspartate plus asparagine, which were 10-32, 15-25, and 8-14% of total protein, respectively. In particular, leucine and glutamine were most abundant in blood meal and casein (13% of total protein), respectively. Notably, gelatin, feather meal, fish meal, meat and bone meal, and poultry byproduct had high percentages of glycine, proline plus hydroxyproline, and arginine, which were 10-35, 9.6-35, and 7.2-7.9% of total protein, respectively. Among plant products, arginine was most abundant in peanut meal and cottonseed meal (14-16% of total protein), whereas corn and sorghum had low percentages of cysteine, lysine, methionine, and tryptophan (0.9-3% of total protein). Overall, feed ingredients of animal origin (except for gelatin) are excellent sources of NEAA and EAA for livestock, avian, and aquatic species, whereas gelatin provides highest amounts of arginine, glycine, and proline plus hydroxyproline. Because casein, corn, soybean, peanut, fish, and gelatin are consumed by children and adults, our findings also have important implications for human nutrition.

Upregulation of growth signaling and nutrient transporters in cotyledons of early to mid-gestational nutrient restricted ewes

Multiparous ewes received 100% (control, C, n = 13) or 50% (nutrient restricted, NR, n = 14) of NRC dietary requirements from d28-d78 of gestation. On d78, 5 C and 6 NR ewes were necropsied. The remaining 8 C and 8 NR ewes were fed to 100% of NRC from d78-d135 and necropsied. Maternal blood was collected at both necropsies and at weekly intervals for assay of glucose, insulin and leptin. Fetal blood was collected at d78 and d135 necropsies for assay of glucose and lipids. Cotyledonary (COT) tissue was evaluated for protein and mRNA expression [fatty acid transporter (FATP)1, FATP4, CD36, glucose transporter (GLUT)1 and GLUT3], mRNA expression only [placenta fatty acid binding protein (FABPpm) and lipoprotein lipase (LPL)], or expression of phosphorylated and total protein forms [AMP kinase (AMPK)α, acetyl-CoA carboxylase (ACC), extracellular signal-regulated kinase (Erk)1/2, mammalian target of rapamycin (mTOR) and protein kinase B (Akt)]. On d78, but not d135, placental and fetal weights were reduced (P < 0.05) in NR vs. C ewes. Maternal circulating glucose, insulin and leptin levels were decreased in NR vs. C ewes on d78 (P < 0.05) but similar at d135. Fetal blood glucose and triglyceride levels were lower in NR vs. C ewes (P < 0.05) on d78, but similar on d135. On d78, GLUT1, FATP4, CD36 mRNA and protein expression levels, FABPpm mRNA level, and leptin protein level were all increased (P < 0.05) in COT of NR vs. C ewes. AMPK, ACC, and Erk1/2 activities were also increased (P < 0.05) in NR vs. C COT on d78. In contrast, only FATP4 was increased (P < 0.05) at both the mRNA and protein levels in COT of NR realimented vs. C ewes on d135. These data demonstrate placental adaptation to maternal NR through increasing nutrient transporter production and growth signaling activity.

Effects of twin-bearing ewe nutritional treatments on ewe and lamb performance to weaning

Nutrition of the ewe at various stages of pregnancy is known to affect ewe and offspring performance. However, little is known regarding the potential interactions among differing maternal nutrition regimens in early and mid–late pregnancy. The objective of the present study was to examine the effects and potential interactions of three pastoral nutritional treatments from Day 21 of pregnancy (P21) to P50 (Sub-maintenanceP21–50 (total liveweight change achieved, SMP21-50, –0.15 ± 0.02 kg/day) v. MaintenanceP21–50 (MP21-50,–0.02 ± 0.02 kg/day) v. Ad libitumP21–50 (AdP21-50,0.15 ± 0.02 kg/day) and two pastoral nutritional treatments from P50 to P139 [MaintenanceP50–139 (designed to match change in conceptus mass, total liveweight change achieved, 0.19 ± 0.01 kg/day) v. Ad libitumP50–139 (0.26 ± 0.01 kg/day)] on 382 twin-bearing ewes and their offspring until 91 days after the mid-point of lambing (L91). Ewe liveweight and condition scores in pregnancy and lactation, and lamb liveweights, indices of colostrum uptake and survival were recorded. There were no interactions between nutritional periods for lamb liveweight, apparent colostrum intake and survival, and ewe liveweight, condition score and total weight of lamb per ewe at the end of the study. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on either ewe liveweight or body condition score. Ewe nutritional treatment during P21–50 had no effect on lamb birthweight. Lambs born to AdP50–139 ewes were lighter (P < 0.05) than those born to MP50–139 ewes (5.32 ± 0.04 v. 5.48 ± 0.04 kg, respectively). Ewe nutritional treatment during P21–50 or P50–139 had no (P > 0.05) effect on indices of colostrum uptake in lambs at 24–36 h of age. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on lamb liveweight, survival or total weight of lamb per ewe. In conclusion, although considerable differences in ewe liveweight were observed during pregnancy, the nutritional treatments had no effect on the production parameters measured at the end of the study. These results indicate, first, that farmers can use early pregnancy as a period to control ewe nutrition when ewes are offered at least pregnancy maintenance levels of nutrition in the mid–late pregnancy period and, second, that there is no advantage from offering twin-bearing ewes a level of nutrition above their pregnancy maintenance requirements in mid–late pregnancy.

Triennial Growth Symposium: important roles for L-glutamine in swine nutrition and production

L-Glutamine (Gln) has traditionally not been considered a nutrient needed in diets for livestock species or even mentioned in classic animal nutrition textbooks. This is due to previous technical difficulties in Gln analysis and the unsubstantiated assumption that animals can synthesize sufficient amounts of Gln to meet their needs. Consequently, the current (1998) version of NRC does not recommend dietary Gln requirements for swine. This lack of knowledge about Gln nutrition has contributed to suboptimal efficiency of global pig production. Because of recent advances in research, Gln is now known to be an abundant AA in physiological fluids and proteins and a key regulator of gene expression. Additionally, Gln can regulate cell signaling via the mammalian target of rapamycin pathway, adenosine monophosphate-activated protein kinase, extracellular signal-related kinase, Jun kinase, mitogen-activated protein kinase, and nitric oxide. The exquisite integration of Gln-dependent regulatory networks has profound effects on cell proliferation, differentiation, migration, metabolism, homeostasis, survival, and function. As a result of translating basic research into practice, dietary supplementation with 1% Gln maintains gut health and prevents intestinal dysfunction in low-birth-weight or early-weaned piglets while increasing their growth performance and survival. In addition, supplementing 1% Gln to a corn- and soybean-meal-based diet between d 90 and 114 of gestation ameliorates fetal growth retardation in gilts and reduces preweaning mortality of piglets. Furthermore, dietary supplementation with 1% Gln enhances milk production by lactating sows. Thus, adequate amounts of dietary Gln, a major nutrient, are necessary to support the maximum growth, development, and production performance of swine.

Impacts of maternal selenium and nutritional level on growth, adiposity, and glucose tolerance in female offspring in sheep

To examine effects of maternal nutrition and Se intake on adiposity and insulin sensitivity in female offspring, treatments were imposed during gestation on 82 pregnant primiparous Rambouillet ewe lambs (52.2 ± 0.8 kg) allotted randomly to 1 of 6 treatments in a 2 × 3 factorial arrangement. Factors were adequate (9.5 μg Se·kg BW(-1)·d(-1); ASe) or high (81.8 μg Se·kg BW(-1)·d(-1); HSe) levels of dietary Se (Se-enriched yeast) and maternal nutritional intake (100% of metabolizable energy [ME] requirement [MOD], 60% of MOD [LOW], and 140% of MOD [HIGH]). Selenium treatments were initiated at breeding and global nutritional treatments at day 50 of gestation. At parturition, lambs were removed from ewes before nursing and managed similarly. Glucose tolerance tests were performed at 107 and 148 d of age. Necropsies were performed at 180 d of age. Although there was no effect of Se on maternal body condition or weight during gestation, both maternal nutritional intake and selenium treatment influenced (P ≤ 0.04) offspring growth and response to a glucose tolerance test. Female lambs from HSe ewes were heavier (P = 0.04) at birth. There were nutritional intake and Se interactions (P ≤ 0.05) on the growth rate of the lambs and their insulin response to a glucose bolus at 2 different times during growth. By 180 d, ewe lambs from HSe ewes had more (P ≤ 0.07) internal fat stores than lambs from ASe ewes. It appears that both maternal nutritional level and Se intake can influence insulin sensitivity, and maternal Se intake alone can enhance fat deposition in female offspring.

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth

The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.

Parenteral administration of L-arginine prevents fetal growth restriction in undernourished ewes

Intrauterine growth restriction (IUGR) is a major health problem worldwide that currently lacks an effective therapeutic solution. This study was conducted with an ovine IUGR model to test the hypothesis that parenteral administration of l-arginine (Arg) is effective in enhancing fetal growth. Beginning on d 28 of gestation, ewes were fed a diet providing 100% (control-fed) or 50% (underfed) of NRC-recommended nutrient requirements. Between d 60 of gestation and parturition, underfed ewes received i.v. infusions of saline or 155 micromol Arg-HCl/kg body weight 3 times daily, whereas control-fed ewes received only saline. The birth weights of lambs from saline-infused underfed ewes were 23% lower (P < 0.01) than those of lambs from control-fed dams. Administration of Arg to underfed ewes increased (P < 0.01) concentrations of Arg (69%), ornithine (55%), proline (29%), methionine (37%), leucine (36%), isoleucine (35%), cysteine (19%), and FFA (43%) in maternal serum, decreased maternal circulating levels of ammonia (18%) and triglycerides (32%), and enhanced birth weights of lambs by 21% compared with saline-infused underfed ewes. There was no difference in birth weights of lambs between the control-fed and the Arg-infused underfed ewes. These novel results indicate that parenteral administration of Arg to underfed ewes prevented fetal growth restriction and provide support for its clinical use to ameliorate IUGR in humans. The findings also lay a new framework for studying cellular and molecular mechanisms responsible for the beneficial effects of Arg in regulating conceptus growth and development.

Nutritional programming of gastrointestinal tract development. Is the pig a good model for man?

The consequences of early-life nutritional programming in man and other mammalian species have been studied chiefly at the metabolic level. Very few studies, if any, have been performed in the gastrointestinal tract (GIT) as the target organ, but extensive GIT studies are needed since the GIT plays a key role in nutrient supply and has an impact on functions of the entire organism. The possible deleterious effects of nutritional programming at the metabolic level were discovered following epidemiological studies in human subjects, and confirmed in animal models. Investigating the impact of programming on GIT structure and function would need appropriate animal models due to ethical restrictions in the use of human subjects. The aim of the present review is to discuss the use of pigs as an animal model as a compromise between ethically acceptable animal studies and the requirement of data which can be interpolated to the human situation. In nutritional programming studies, rodents are the most frequently used model for man, but GIT development and digestive function in rodents are considerably different from those in man. In that aspect, the pig GIT is much closer to the human than that of rodents. The swine species is closely comparable with man in many nutritional and digestive aspects, and thus provides ample opportunity to be used in investigations on the consequences of nutritional programming for the GIT. In particular, the 'sow-piglets' dyad could be a useful tool to simulate the 'human mother-infant' dyad in studies which examine short-, middle- and long-term effects and is suggested as the reference model.

Heat shock protein 70 is upregulated in the intestine of intrauterine growth retardation piglets

The objective of this study is to investigate the expression and distribution of heat shock protein 70 (Hsp70) in the intestine of intrauterine growth retardation (IUGR) piglets. Samples from the duodenum, prejejunum, distal jejunum, ileum, and colon of IUGR and normal-body-weight (NBW) piglets were collected at birth. The results indicated that the body and intestine weight of IUGR piglets were significantly lower than NBW piglets. The villus height and villus/crypt ratio in jejunum and ileum of IUGR piglets were significantly reduced compared to NBW piglets. These results indicated that IUGR causes abnormal gastrointestinal morphologies and gastrointestinal dysfunction. The mRNA of hsp70 was increased in prejejunum (P < 0.05), distal jejunum (P < 0.05), and colon in IUGR piglets. However, the hsp70 mRNA in ileum of piglets with IUGR was decreased. Similar to hsp70 mRNA, the protein levels of Hsp70 in prejejunum (P < 0.05), distal jejunum, and colon (P < 0.05) in IUGR piglets were higher than those in NBW piglets. These results indicated that the expression of Hsp70 in the intestinal piglets was upregulated by IUGR, and different intestinal sites had different responses to stress. Meanwhile, the localization of Hsp70 in the epithelial cells of the whole villi and intestinal gland rather than in the lamina propria and myenteron suggested that Hsp70 has a cytoprotective role in epithelial cell function and structure.

Effects of ewe size and nutrition during pregnancy on glucose metabolism, fat metabolism and adrenal function of postpubertal female twin offspring

Little is known about the long-term metabolic effects of maternal constraint on the offspring and whether a possible interaction of dam size and nutrition during gestation exists, affecting postnatal metabolic functions in the offspring. Four hundred and fifty heavy (H) (60.8 ± 0.18 kg) and 450 light (L) (42.5 ± 0.17 kg) Romney dams were allocated to ad libitum (A) or maintenance (M) nutritional regimens under New Zealand pastoral grazing conditions, from Day 21 to 140 after insemination. One week before lambing, all dams and offspring were managed as one group and provided with ad libitum feeding. At 16 months of age, female twin-born offspring (n = 12 per size by nutrition group) were catheterised and given intravenous insulin (0.15 IU/kg) (ITT), glucose (0.17 g/kg) (GTT) and epinephrine (1 μg/kg) (ETT) challenges to assess their glucose and fat metabolism and adrenal function. No effects of dam size or interactions between dam size and dam nutrition were found on glucose or fat metabolism or adrenal function. In response to the ETT, M-dam offspring showed greater (P < 0.05) peak glucose concentrations, increased (P < 0.05) glucose area under the curve and tended (P < 0.10) to have increased maximum change in glucose and non-esterified free fatty acid concentrations compared with A-ewes. No effects of dam nutrition were found on glucose tolerance, insulin resistance or adrenal function in response to GTT and ITT. In conclusion, dam size had no effect on glucose metabolism, adrenal function or fat metabolism in 16-month-old female twin offspring. Dam nutrition during pregnancy from Day 21 to 140 had no major effect on glucose metabolism, adrenal function or lipolysis; however, it did potentially affect gluconeogenesis and/or glycogenolysis, as increased glucose concentrations in ewes born to M-fed dams were observed in response to ETT. These results indicate that M-ewes could have an advantage over A-ewes in physiological stressful situations in life (e.g. pregnancy, lactation) as their liver may be able to supply more glucose to support their growing conceptus and milk production to increase the chances of survival of their offspring.

Relationships between early postnatal growth and metabolic function of 16-month-old female offspring born to ewes exposed to different environments during pregnancy

It was hypothesized that exposure of the fetus to adverse conditions in utero due to either maternal constraint or nutrition may result in developmental adaptations altering metabolism and postnatal growth of the offspring. Heavy (H) and light (L) Romney dams (G0) were allocated to ad libitum (A) or maintenance (M) nutritional regimens, from day 21–day 140 of pregnancy. Female twin-born offspring (G1) born to the dams in the four treatment groups will be referred to as HA-ewes, LA-ewes, HM-ewes and LM-ewes. At 16 months of age, offspring were catheterized and given intravenous insulin tolerance test (ITT), glucose tolerance test (GTT) and epinephrine tolerance test challenges to assess their glucose and fat metabolism in relation to their birth weight and postnatal growth. In HA-ewes, the regression coefficients of growth rates prior to puberty on insulin and glucose curves in response to GTT (InsAUCGTT) and ITT (GluAUCITT), respectively, were different from 0 (P < 0.05) and were different from the regression coefficients of HM-ewes. This may indicate that HA-ewes may have showed puberty-related insulin resistance at 16 months of age with increasing growth rates prior to puberty compared to HM- or LM-ewes. In HM-ewes, the regression coefficients of growth rates after puberty on InsAUCGTT and GluAUCITT were different from 0 (P < 0.05) and were different from those of HA-ewes. These results may indicate that offspring born to heavy dams fed maintenance during pregnancy and with greater postnatal growth rates after puberty could develop glucose intolerance and insulin resistance in later life.

Accounting for additive genetic mutations on litter size in Ripollesa sheep

Little is known about mutational variability in livestock, among which only a few mutations with relatively large effects have been reported. In this manuscript, mutational variability was analyzed in 1,765 litter size records from 404 Ripollesa ewes to characterize the magnitude of this genetic source of variation and check the suitability of including mutational effects in genetic evaluations of this breed. Threshold animal models accounting for additive genetic mutations were preferred to models without mutational contributions, with an average difference in the deviance information criterion of more than 5 units. Moreover, the statistical relevance of the additive genetic mutation term was checked through a Bayes factor approach, which showed that the models with mutational variability were 8.5 to 22.7 times more probable than the others. The mutational heritability (percentage of the phenotypic variance accounted for by mutational variance) was 0.6 or 0.9%, depending on whether genetic dominance effects were accounted for by the analytical model. The inclusion of mutational effects in the genetic model for evaluating litter size in Ripollesa ewes called for some minor modifications in the genetic merit order of the individuals evaluated, which suggested that the continuous uploading of new additive mutations could be taken into account to optimize the selection scheme. This study is the first attempt to estimate mutational variances in a livestock species and thereby contribute to better characterization of the genetic background of productive traits of interest.

Developmental programming: the concept, large animal models, and the key role of uteroplacental vascular development

Developmental programming refers to the programming of various bodily systems and processes by a stressor of the maternal system during pregnancy or during the neonatal period. Such stressors include nutritional stress, multiple pregnancy (i.e., increased numbers of fetuses in the gravid uterus), environmental stress (e.g., high environmental temperature, high altitude, prenatal steroid exposure), gynecological immaturity, and maternal or fetal genotype. Programming refers to impaired function of numerous bodily systems or processes, leading to poor growth, altered body composition, metabolic dysfunction, and poor productivity (e.g., poor growth, reproductive dysfunction) of the offspring throughout their lifespan and even across generations. A key component of developmental programming seems to be placental dysfunction, leading to altered fetal growth and development. We discuss various large animal models of developmental programming and how they have and will continue to contribute to our understanding of the mechanisms underlying altered placental function and developmental programming, and, further, how large animal models also will be critical to the identification and application of therapeutic strategies that will alleviate the negative consequences of developmental programming to improve offspring performance in livestock production and human medicine.

Dam and granddam feeding during pregnancy in sheep affects milk supply in offspring and reproductive performance in grand-offspring

In temperate climates, the cost of providing feed is greater in winter than in other seasons, causing ewes to be fed restricted rations during some periods of pregnancy. Epidemiological information indicates that undernutrition of the fetus may affect its health and performance in later life (i.e., fetal programming), and these effects may be passed between generations. The primary focus of the results presented in this paper is to examine the effects of feeding levels during pregnancy on a variety of traits from offspring at the fetal stage to 3.5 yr of age and also traits in the grand-offspring. Two studies are reported in which ewes were fed restricted diets during pregnancy, with a variety of fetal traits, offspring traits up to 3.5 yr of age, or grand-offspring traits up to 8 mo of age being measured. Study 2 also considered differences in dam size (heavy vs. light). In study 1, several fetal mammary gland measures indicated that milking ability may be enhanced in offspring from dams fed ad libitum during pregnancy. However, study 2 showed that mammary mass was greater in fetuses from dams fed at maintenance during pregnancy and that contemporaries of these fetuses produced greater protein and lactose yields in their first lactation. In the second lactation, the advantages in protein and lactose yields did not reoccur and ewes from ad libitum-fed dams produced greater fat yield. In study 2, grand-offspring whose granddams were fed at maintenance levels during pregnancy were lighter at birth in both the first and second parturitions than those whose granddams were fed ad libitum during pregnancy. First-parity grand-offspring whose granddams were fed maintenance levels during pregnancy achieved heavier BW by 40 to 50 d of age in the first lactation, which reflected the greater protein and lactose yields; however, no BW differences were present in second-parity lambs at the same age. A smaller proportion of first-parity ewe grand-offspring from heavy granddams that were fed ad libitum during pregnancy reached puberty at approximately 8 mo of age relative to the other granddam size and feeding groups. These results indicate that dam nutrition can affect the yield and composition of milk in their offspring and the BW and reproductive capability of their grand-offspring. Molecular and physiological mechanisms for these changes are being sought.

Maternal selenium supplementation and timing of nutrient restriction in pregnant sheep: effects on maternal endocrine status and placental characteristics

To determine the effects of maternal Se intake and plane of nutrition during midgestation, late gestation, or both on hormone and metabolite concentrations in the dam and on placental characteristics, pregnant ewe lambs (n = 64) were assigned to 1 of 8 treatments arranged in a 2 x 2 x 2 factorial array: Se level [initiated at breeding; adequate (3.05 microg/kg of BW) or high (70.4 microg/kg of BW)] and nutritional level [100% (control) or 60% (restricted) of NRC recommendations] fed at different times of gestation [d 50 to 90 (midgestation) or d 91 to 130 (late gestation)]. The control ewes had a greater (P = 0.01) percentage change in BW from d 50 than restricted ewes during both mid- and late gestation. Although blood urea N was not affected by either Se or nutritional level, restricted ewes had greater (P = 0.01) concentrations of circulating Se on d 66, 78, 106, 120, and 130 of gestation compared with control ewes. Both Se and timing of the nutritional level affected circulating progesterone; however, only nutritional level affected thyroxine and triiodothyronine concentrations in the dam. Nutrient restriction during late gestation decreased (P <or= 0.01) fetal BW and fetal fluid weight compared with the control ewes (3.75 vs. 4.13 +/- 0.10 kg and 1.61 vs. 2.11 +/- 0.11 kg). Although neither Se nor nutritional level affected (P >or= 0.1) placental, caruncular, or cotyledonary weights, cotyledonary cellular proliferation was decreased (P < 0.05) in ewes receiving a high concentration of Se compared with those receiving adequate Se. In addition, either Se or nutritional level affected vascular endothelial growth factor (VEGFA), VEGFA-receptor 1, VEGFA-receptor 2, and NO synthase mRNA abundance in the cotyledonary tissue. In the caruncular tissue, either Se or nutritional level affected VEGFA-receptor 1, placental growth factor, and NO synthase mRNA abundance. Selenium supplementation and the duration or timing of nutrient restriction appear to influence the endocrine and metabolic status of the ewe, which may influence nutrient transport and placental function.

Impacts of amino acid nutrition on pregnancy outcome in pigs: mechanisms and implications for swine production

Pigs suffer up to 50% embryonic and fetal loss during gestation and exhibit the most severe naturally occurring intrauterine growth retardation among livestock species. Placental insufficiency is a major factor contributing to suboptimal reproductive performance and reduced birth weights of pigs. Enhancement of placental growth and function through nutritional management offers an effective solution to improving embryonic and fetal survival and growth. We discovered an unusual abundance of the arginine family of AA in porcine allantoic fluid (a reservoir of nutrients) during early gestation, when placental growth is most rapid. Arginine is metabolized to ornithine, proline, and nitric oxide, and these compounds possess a plethora of physiological functions. Nitric oxide is a vasodilator and angiogenic factor, whereas both ornithine and proline are substrates for placental synthesis of polyamines, which are key regulators of protein synthesis and angiogenesis. Additionally, arginine, leucine, glutamine, and proline activate the mammalian target of rapamycin cell-signaling pathway to enhance protein synthesis and cell proliferation in placentae. To translate basic research on AA biochemistry and nutrition into application, dietary supplementation with 0.83% l-arginine to gilts on d 14 to 28 or d 30 to 114 of gestation increased the number and litter birth weight of live-born piglets. In addition, supplementing the gestation diet with 0.4% l-arginine plus 0.6% l-glutamine enhanced the efficiency of nutrient utilization, reduced variation in piglet birth weight, and increased litter birth weight. By regulating syntheses of nitric oxide, polyamines, and proteins, functional AA stimulate placental growth and the transfer of nutrients from mother to embryo or fetus to promote conceptus survival, growth, and development.