Influence of glucocorticoid on macromolecular absorption and passive immunity in neonatal lambs

Late gestation heat stress in dairy cows: Effects on dam and daughter

In dairy cattle, the final weeks before parturition are physiologically challenging and an important determinant of subsequent production performance. External stressors should be carefully managed during this period to avoid adding strain on the animals. Late-gestation heat stress impairs productivity in the dam and exerts transgenerational effects on progeny. Physiological responses are complex and detriments to performance are multifaceted. Late-gestation heat stress blunts mammary gland involution in the first half of the dry period and impairs cell proliferation as calving approaches. Moreover, cows that were exposed to prepartum heat-stress exhibit reduced adipose tissue mobilization and a lower degree of insulin resistance during early lactation. Prepartum heat exposure also depresses immune function and evidence links this decrease to altered prolactin signaling under heat stress. Placental functions are also impaired as reflected in a higher cotyledon mass but lower maternal circulating estrone sulfate concentrations, potentially resulting in lower nutrient supply and reduced calf birth weight. In addition, calves born to heat-stressed dams show impaired immune function and therefore higher disease susceptibly. Novel evidence reported that intrauterine heat stress alters the methylation profile of liver and mammary DNA, which may also contribute to the poorer performance during adulthood of calves exposed to heat stress in utero. Understanding the contribution of all altered biological systems during late-gestation heat stress can be used as a basis for improving cow management during the dry period. This article provides a review of the impacts of late-gestation heat stress and of the emerging understanding of the biological mechanisms that underlie the observed impairments of performance.

Physiological changes in the peri-partum period and colostral IgG transfer in prolific D'man sheep: effects of parity and litter size

The aim of this work was to assess maternal and neonatal changes in plasma proteins, glucose and cortisol and to quantify the colostral immunoglobulin G (IgG) transfer in the peri-partum period in D'man sheep, a prolific breed, taking into account the parity of the ewe. The concentrations of proteins and glucose were high in the ewes on day 7 and at lambing before decreasing. Likewise, cortisol plasma concentration was maximal during the 6 h following lambing and dropped at 12 h. Protein and glucose concentrations were low in lambs at 1 h of birth after which they increased. By contrast, cortisol level was the highest during the first 12 h of birth and then decreased. The colostral IgG level was high at lambing and dropped by over 87 % from 1 to 48 h post-partum. In the newborn, the plasma IgG concentration was lowest at birth and increased rapidly during the first 24 h of birth. Parity influenced maternal physiology with multiparous ewes having the lowest concentrations of proteins, glucose, IgG and cortisol, but the highest colostrum IgG level. Accordingly, lambs born from primiparous ewes had lower protein, glucose and plasma IgG concentrations than lambs born from multiparous ewes. The main outcome of this study was that lambs born from primiparous ewes are characterized by the lowest physiological indices and this may influence their survival chance.

Invited review: Improving neonatal survival in small ruminants: science into practice

Neonatal mortality in small ruminant livestock has remained stubbornly unchanging over the past 40 years, and represents a significant loss of farm income, contributes to wastage and affects animal welfare. Scientific knowledge about the biology of neonatal adaptation after birth has been accumulating but does not appear to have had an impact in improving survival. In this paper, we ask what might be the reasons for the lack of impact of the scientific studies of lamb and kid mortality, and suggest strategies to move forward. Biologically, it is clear that achieving a good intake of colostrum, as soon as possible after birth, is crucial for neonatal survival. This provides fuel for thermoregulation, passive immunological protection and is involved in the development of attachment between the ewe and lamb. The behaviour of the lamb in finding the udder and sucking rapidly after birth is a key component in ensuring sufficient colostrum is ingested. In experimental studies, the main risk factors for lamb mortality are low birthweight, particularly owing to poor maternal nutrition during gestation, birth difficulty, litter size and genetics, which can all be partly attributed to their effect on the speed with which the lamb reaches the udder and sucks. Similarly, on commercial farms, low birthweight and issues with sucking were identified as important contributors to mortality. In epidemiological studies, management factors such as providing assistance with difficult births, were found to be more important than risk factors associated with housing. Social science studies suggest that farmers generally have a positive attitude to improving neonatal mortality but may differ in beliefs about how this can be achieved, with some farmers believing they had no control over early lamb mortality. Facilitative approaches, where farmers and advisors work together to develop neonatal survival strategies, have been shown to be effective in achieving management goals, such as optimising ewe nutrition, that lead to reductions in lamb mortality. We conclude that scientific research is providing useful information on the biology underpinning neonatal survival, such as optimal birthweights, lamb vigour and understanding the importance of sufficient colostrum intake, but the transfer of that knowledge would benefit from an improved understanding of the psychology of management change on farm. Developing tailored solutions, on the basis of adequate farm records, that make use of the now substantial body of scientific literature on neonatal mortality will help to achieve lower neonatal mortality.

Transferência de imunidade passiva em cordeiros de corte manejados extensivamente em clima tropical

Aspectos relacionados à transferência de imunidade passiva (TIP) foram estudados em 290 cordeiros recém-nascidos, cruzas Texel, manejados extensivamente em contato permanente com as suas mães, e criados em clima tropical. Amostras de sangue foram colhidas dos cordeiros uma única vez entre 24 e 36 horas de vida para obtenção do soro sanguíneo. Foram determinadas a atividade da gama glutamiltransferase e as concentrações de proteínas totais por refratometria e colorimetria, de albumina, alfa, beta e gamaglobulinas por eletroforese e de IgG estimada pela turvação pelo sulfato de zinco. Os cordeiros foram agrupados de acordo com o sexo, o número de partos das ovelhas, o escore de condição corporal (ECC) da ovelha, o número de cordeiros nascidos, o peso e a vitalidade ao nascimento. Os fatores de risco para a ocorrência de falha na transferência de imunidade passiva (FTIP) foram identificados e a sua associação com a mortalidade de cordeiros foi testada. Foram estabelecidas correlações entre as variáveis estudadas. A TIP não foi influenciada pelo sexo, pelo número de partos ou pelo ECC das ovelhas. Houve diferenças entre os cordeiros únicos e gêmeos e entre os que nasceram com peso >3 kg e < 3 kg. A FTIP foi pouco frequente (12,4%), mais provável em gêmeos (p=0,026) e em cordeiros leves (p<0,001) e esteve fortemente associada com a mortalidade dos cordeiros até os 60 dias de vida (p<0,001). A taxa de mortalidade geral foi de 11,3%; e 30,5% dos cordeiros com FTIP morreram, quase todos no primeiro mês de vida. A concentração de proteína total determinada por refratometria se correlacionou (p<0,001) com as concentrações de gamaglobulinas (r=0,816) e de IgG (r=0,810) e o valor crítico < 5,0g/dL para a proteína total pode ser admitido como indicador de FTIP. Sob condições de clima tropical a FTIP pode ser considerada pouco frequente em cordeiros mestiços de corte, entretanto, a vigilância e os cuidados devem ser intensificados no caso do nascimento de cordeiros gêmeos com peso reduzido.

Effects of colostrum replacer supplemented with lactoferrin on the blood plasma immunoglobulin G concentration and intestinal absorption of xylose in the neonatal calf

The objective of this experiment was to determine the effect of lactoferrin (Lf) supplementation of colostrum replacer (CR) fed as 1 or 2 doses on apparent efficiency of IgG absorption, serum IgG concentrations, and xylose absorption/intestinal development in neonatal Holstein bull calves. Eighty bull calves were assigned to a 2 x 4 factorial arrangement of treatments in a randomized complete block design. Calves used were from the University of New Hampshire (n = 48) or a commercial dairy (n = 32). All calves were fed CR according to manufacturer's recommendations +/- Lf treatment within 90 min of birth. Lactoferrin treatments were 0 (control), 0.5, 1, and 2 g/d of supplemental Lf. At 12 h of age, calves were fed a second feeding of CR +/- supplemental Lf or 2 L of milk replacer +/- supplemental Lf. Calves continued to be fed milk replacer +/- supplemental Lf every 12 h for the duration of study. Blood samples were collected for determination of IgG and total serum protein at 0, 6, 12, 18, 24, and 48 h. Calves, except those fed 1 dose of CR plus 1 or 2 g of Lf, had serum IgG concentrations > or = 10 g/L at 24 h. Lactoferrin supplementation had no effect on serum IgG or total serum protein concentrations. Calves fed 2 doses of CR had greater serum IgG concentrations compared with calves fed 1 dose of CR. Apparent efficiency of absorption of IgG was less in calves fed 2 doses of CR compared with calves fed 1 dose of CR. Lactoferrin supplementation (up to 1 g/d) resulted in decreased apparent efficiency of absorption of IgG. At the sixth feeding (60 +/- 2 h of age), D-xylose (0.5 g/kg BW) was mixed with milk replacer +/- supplemental Lf (n = 48) to determine xylose absorption by the small intestine. Blood was collected at 0, 2, 4, 6, 8, and 12 h after feeding xylose for determination of plasma glucose and xylose concentrations. Xylose means and area under the curve resulted in quadratic effects. Feeding calves 0.5 or 1 g/d supplemental Lf resulted in decreased plasma xylose concentrations compared with calves fed 0 or 2 g/d of supplemental Lf. Colostrum replacer or supplemental Lf did not affect plasma glucose concentrations. This study indicates that supplementing Lf at 0.5 or 1 g/d to calves fed CR has a negative effect on apparent efficiency of IgG absorption and xylose absorption.

Gut responses to enteral nutrition in preterm infants and animals

Preterm birth is associated with immature digestive function that may require the use of total parenteral nutrition and special oral feeding regimens. Little is known about the responses to oral food in the preterm neonate and how enteral nutrients affect the immature gastrointestinal tract (GIT). In vivo studies are difficult to perform in laboratory rodents because of their small body size and that of immature organs at birth, and this makes the large farm animals (e.g., pigs, cattle, sheep) more attractive models in this field. In these species, preterm delivery at 88%-95% gestation is associated clinical complications and degrees of GIT immaturity similar to those in infants born at 70%-90% gestation. Studies in both animals and infants indicate that the immature GIT responds to the first enteral food with rapid increases in gut mass and surface area, blood flow, motility, digestive capacity, and nutrient absorption. To a large extent, the enteral food responses are birth independent, and can be elicited also in utero, at least during late gestation. Nevertheless, preterm neonates show compromised GIT structure, function, and immunology, particularly when delivered by caesarean section and fed diets other than mother's milk. Formula-fed preterm infants are thus at increased risk of developing diseases such as necrotizing enterocolitis, unless special care is taken to avoid excessive nutrient fermentation and bacterial overgrowth. The extent to which results obtained in preterm animals (most notably the pig) can be used to reflect similar conditions in preterm infants is discussed.

Macromolecule absorption and cortisol secretion in newborn calves derived from in vitro produced embryos

Earlier reports indicate that calves derived from in vitro produced (IVP) embryos are more susceptible to neonatal disease than calves produced after artificial insemination (AI) or natural mating. The aims of the present study were to investigate whether calves born after IVP embryos show an altered macromolecule absorption (immunoglobulin G (IgG) and porcine serum albumin (PSA)) compared with AI calves and whether the macromolecule absorption could be related to the degree of acidosis or to the cortisol secretion around birth. Hence, IgG and PSA absorption in control AI calves (n=7) was compared with that in two groups of IVP calves (IVP-defined: SOFaa embryo culture with polyvinyl alcohol, n=6; IVP-serum: SOFaa embryo culture with serum and co-culture, n=8). The calves were fed colostrum (40ml/kg) at 2, 6 and 12h after birth. At 24h after birth, both AI and IVP calves had achieved a level of plasma IgG sufficient to provide passive immunization (>15mg/ml). When the values were adjusted for the varying colostral IgG contents and the degree of acidosis, the IVP-defined calves had significantly lower peak plasma IgG concentrations than the AI calves at 18-24h after birth (P<0.04). However, when the macromolecule marker (PSA), was fed to all calves at 2 and 12h after birth the resulting plasma PSA levels were significantly lower in the AI calves compared with the IVP calves during the whole observation period (P<0.0001). Calves with a moderate neonatal acidosis (mean pH<7.2 during the first 30min after birth) had reduced peak plasma IgG concentration at 18-24h after birth (P<0.02) compared to calves without acidosis. The basal and ACTH-stimulated cortisol levels were lower in the newborn IVP-defined calves than in the AI calves (P<0.05) and the IVP-serum calves (P<0.002). Cortisol levels shortly after birth correlated positively with birth weight (r=0.60, P<0.0001) and with gestation length (r=0.34, P<0.04). Since, the IVP calves absorbed sufficient amounts of IgG from colostrum to acquire sufficient passive immunity, we conclude that the lower viability described in IVP offspring probably is not caused by an impaired passive immunization. IVP-defined calves had significantly lower absorption efficiency of IgG compared with AI calves, whereas absorption of a non-Ig macromolecule (PSA) was higher for IVP than AI calves. This might indicate a more selective absorption in AI calves in favor of IgG. Acidosis around birth affected immunoglobulin absorption negatively. IVP-defined calves had significantly lower cortisol levels the first 3h after birth and during an ACTH-challenge and a lower IgG absorption efficiency, which might indicate a mild degree of organ dysmaturity in these calves.

Development of intestinal transport function in mammals

Considerable progress has been made over the last decade in the understanding of mechanisms responsible for the ontogenetic changes of mammalian intestine. This review presents the current knowledge about the development of intestinal transport function in the context of intestinal mucosa ontogeny. The review predominantly focuses on signals that trigger and/or modulate the developmental changes of intestinal transport. After an overview of the proliferation and differentiation of intestinal mucosa, data about the bidirectional traffic (absorption and secretion) across the developing intestinal epithelium are presented. The largest part of the review is devoted to the description of developmental patterns concerning the absorption of nutrients, ions, water, vitamins, trace elements, and milk-borne biologically active substances. Furthermore, the review examines the development of intestinal secretion that has a variety of functions including maintenance of the fluidity of the intestinal content, lubrication of mucosal surface, and mucosal protection. The age-dependent shifts of absorption and secretion are the subject of integrated regulatory mechanisms, and hence, the input of hormonal, nervous, immune, and dietary signals is reviewed. Finally, the utilization of energy for transport processes in the developing intestine is highlighted, and the interactions between various sources of energy are discussed. The review ends with suggestions concerning possible directions of future research.

Effect of dietary IgG source (colostrum, serum, or milk-derived supplement) on the efficiency of Ig absorption in newborn Holstein calves

This study was designed to compare the absorptive efficiency of IgG from a commercial bovine serum product (bovine serum), cow colostrum (positive control), and two commercial milk-derived IgG supplements (supplement 1 and supplement 2). Newborn Holstein calves, collected at birth and prior to the consumption of colostrum, were allotted to treatment by alternating birth order. Colostrum supplement treatments were fed according to manufacturer's recommendations at birth and again at 12 h. This strategy resulted in varying masses of total IgG being offered to the calves (200, 90, 50, and 60 g of IgG for colostrum, bovine serum, supplement 1, and supplement 2, respectively). Blood samples were collected at 0, 12, and 24 h after the end of treatment administration. Plasma volume was estimated as 9.10% of birth weight. Apparent efficiency of IgG absorption at 24 h was determined. Plasma IgG concentrations at 24 h differed for each treatment (12.1, 6.8, 2.2, and 3.5 g of IgG/L for colostrum, bovine serum, supplement 1, and supplement 2, respectively). Apparent efficiency of IgG absorption was greatest for bovine serum compared with colostrum and supplement 1. No treatment differences were detected on the occurrence of mortality. However, calves fed bovine serum tended to have fewer treatments for illness compared with calves fed colostrum and supplement 1. Calves receiving bovine serum-derived IgG had improved IgG absorption efficiency and a tendency toward fewer medical treatments compared with calves consuming colostrum or a dried colostrum product.

Alterations of growth hormone, cortisol, luteinizing hormone, and insulin concentrations in early-postnatal calves affected with diarrhea

The aim of the study was to investigate the influence of diarrheic infections during the early postnatal phase of calves on the concentrations of hormones controlling reproduction and metabolism. Blood samples were collected from 20 male and female calves via jugular vein catheters every 15 min for 6 hr at Days 3, 9, and 21 of life. The animals were classified into three groups. Group 1 (controls): healthy calves (n = 9). Group 2: calves affected with diarrhea at Day 9 (n = 7). Group 3: calves with diarrhea at Days 3 and 9 (n = 4). Infections occurred spontaneously and were mainly due to E. coli infections. All affected calves had recovered at Day 21. Mean GH concentrations in the calves in Groups 2 and 3 compared to control calves had increased by Day 3 (P<0.01; P<0.001). Cortisol levels of calves in all groups were highest at Day 3 and decreased thereafter (P<0.001). Cortisol concentrations were lower at Day 3 in animals in Groups 2 (P<0.001) and 3 (P<0.05) than in controls. Pulsatile LH release was detectable at Days 9 and 21 only in healthy calves. Insulin increased at Day 9 during diarrhea. The results indicate that cortisol concentrations decreased whereas GH concentrations were increased before diarrhea was observed. The onset of pulsatile LH release was delayed in diarrheic calves. It is concluded that diarrhea exerts effects upon the release of reproductive and metabolic hormones in early postnatal calves.

Intestinal macromolecule absorption in the fetal pig after infusion of colostrum in utero

The ability of the fetal pig intestine to absorb large proteins was investigated in utero. Six pregnant sows were anesthetized (Na pentobarbital) at 99-102 d of gestation (term = 115 +/- 2 d), and a catheter was inserted into the esophagus of two to three fetuses per sow. Via these catheters, sterile solutions (10.0 mL) of colostrum whey (CW, n = 5), milk whey (MW, n = 5), or amniotic fluid (AF, n = 4) were infused into the fetal pig stomachs every 6 h for 6-8 d starting on the day after surgery (d 0). Levels of IgG in the three fluids were 120, 0.5, and 0 mg/mL, respectively. During the first 2-3 d of infusion, plasma IgG levels rose rapidly in the CW fetuses (to 7.5 +/- 0.8 mg/mL), whereas IgG remained absent in plasma from MW and AF fetuses. Absorption of a macromolecule marker, BSA, was also higher when the marker was given with CW rather than with MW or AF. However, when all three treatment groups were given CW + BSA on the last experimental day (d 6-8), the mean BSA increment in the CW group was only 5-8% of that in the AF group, with intermediate values for the MW group. Neither at the beginning nor at the end of the experiment was macromolecule uptake in individual CW fetuses correlated with their cortisol level in plasma. The prenatal pig intestine is similar to the neonatal pig intestine in that colostrum stimulates both the macromolecule absorption and the cessation of macromolecule uptake (intestinal closure). However, fetal pigs have a lower protein absorptive capacity and a longer preclosure period than newborn pigs; this may be related to an immature structure and function and a slow enterocyte proliferation rate in the prenatal pig intestine.

Systemic and luminal influences on the perinatal development of the gut

At birth, the mammalian gastrointestinal tract (GIT) must be able to support a shift from mainly parenteral nutrition in the fetus (via the placenta) to enteral nutrition in the neonate. In the perinatal period the GIT therefore undergoes enhanced growth as well as morphological and functional differentiation, and this maturational programme is influenced by a complex interplay of local, systemic and luminal factors. This review shows how systemic and luminal factors may influence GIT development in the perinatal period of the pig and sheep, two long-gestation species. Adrenocortical hormones play a pivotal role in the prepartum maturation of the GIT in addition to their better known effects on the development of many other tissues and body systems. More particularly, in the fetal pig and sheep, the prenatal development of gastric acid and gastrin secretion, and of GIT hydrolase activities (chymosin, pepsin, amylase, lactase, aminopeptidases) is influenced by cortisol. Additionally, glucocorticoids exert effects throughout the GIT by influencing morphological, cytological, and functional differentiation. Since the GIT epithelial cells comprise a renewing cell population there are also changes in cell kinetics. In addition to systemic factors, the presence of growth factors, hormones and nutrients from swallowed amniotic fluid (fetus) and colostrum (neonate) may influence GIT development. In utero, fetal fluid ingestion has been shown to modulate tissue growth, macromolecule and immunoglobulin transport, enterocyte differentiation, cell turnover and activity of brush-border hydrolases. These effects may be mediated via regulatory peptides (e.g. insulin-like growth factor I, gastrin-releasing peptides, insulin, epidermal growth factor, gastrin). A physiological role of luminally derived growth factors is supported by a number of unique structural and functional adaptations of the GIT in the fetus and neonate (low luminal proteolysis, intestinal macromolecule transport). Thus, in the pig and sheep, both systemic and luminal factors appear to play critical roles in GIT development in the perinatal period.