mRNA of insulin-like growth factor (IGF) quantification and presence of IGF binding proteins, and receptors for growth hormone, IGF-I and insulin, determined by reverse transcribed polymerase chain reaction, in the liver of growing and mature male cattle

Characterization of circular RNA profiles of oviduct reveal the potential mechanism in prolificacy trait of goat in the estrus cycle

The mammalian oviduct is functionally highly diverse during the estrus cycle. It provides a suitable milieu for oocyte maturation, sperm capacitation, fertilization, early embryo development and transportation. While there have been many studies of molecular mechanisms on the kidding number of goats, a systematic analysis by which the underlying circular RNAs (circRNAs) changes in the oviduct related to prolificacy traits is lacking. Herein, we present a comprehensive circRNA atlas of the oviduct among high- and low-fecundity goats in the follicular phase (FH vs. FL), luteal phase (LH vs. LL), and estrus cycle (FH vs. LH; FL vs. LL) to unravel their potential regulatory mechanisms in improving kidding number. We generated RNA sequencing data, and identified 4,078 circRNAs from twenty sampled Yunshang black goats. Many of these circRNAs are exon-derived and differentially expressed between each comparison group. Subsequently, eight differentially expressed (DE) circRNAs were validated by RT‒qPCR, which was consistent with the RNA-seq data. GO and KEGG enrichment analyses suggested that numerous host genes of DE circRNAs were involved in the hormone secretion, gamete production, fertilization, and embryo development processes. The competing endogenous RNA (ceRNA) interaction network analysis revealed that 2,673 circRNA–miRNA–mRNA axes (including 15 DE circRNAs, 14 miRNAs, and 1,699 mRNAs) were formed, and several target genes derived from the ceRNA network were associated with oviduct functions and reproduction, including SMAD1, BMPR1B, IGF1, REV1, and BMP2K. Furthermore, miR-15a-5p, miR-181b-5p, miR-23b-5p, miR-204-3p, and miR-145-5p might play important roles in reproduction. Finally, a novel circRNA, circIQCG, was identified as potentially involved in embryo development. Overall, our study provides a resource of circRNAs to understand the oviductal function and its connection to prolificacy trait of goats in the differentiation estrus cycle.

Effect of postpartum collection time and colostrum quality on passive transfer of immunity, performance, and small intestinal development in preweaning calves

This study evaluated the effects of postpartum collection time and quality of colostrum fed to calves on the failure of passive transfer, growth, and small intestine development in the first 5 wk of life. Newborn calves (Holstein-Friesian × Jersey) were identified at birth and collected either early (E; within 12 h postpartum; n = 20) or late (L; 18-24 h postpartum; n = 20) and fed either high-quality colostrum [HQC, first milking colostrum with Brix% = 23 ± standard deviation (SD) 2] or low-quality colostrum (LQC, mixed colostrum and transition milk with Brix% = 12 ± 1) to create 4 treatments: E-HQC, E-LQC, L-HQC, and L-LQC (n = 10/treatment). After collection, calves (body weight = 32.3 ± 4.6 kg/calf) were fed either HQC or LQC (7.5% of their arrival body weight per feed) for the first 3 (L calves) or 4 feedings (E calves). All calves were then managed and fed similarly using automatic feeders which recorded individual intake of milk replacer and calf starter. Blood samples were taken at d 1 (after collection from dams but before colostrum feeding), 4, 14, and 35 of age to analyze selected metabolites. All calves were killed at d 35 ± 2 of age and histomorphology of duodenum, jejunum, and ileum was evaluated. At collection, 75% of E calves and 58% of L calves had serum total protein ≤52 g/L. At d 4 of age, calves fed HQC had greater serum total protein than calves fed LQC; however, failure of passive transfer (serum total protein ≤52 g/L) incidence did not differ between HQC and LQC. Collection time did not affect the scouring duration, but the amount of electrolyte used to treat sick calves was lower in L versus E calves, whereas feeding HQC versus LQC lowered both the scouring duration and electrolyte use to treat sick calves. Calves fed HQC had a greater total surface area of the duodenum (+23%) and jejunum (+17%) compared with LQC calves. Duodenal crypts were deeper in E-LQC calves than E-HQC and L-HQC calves, whereas L-LQC calves were intermediate. Villus height to crypt depth ratio in duodenum, jejunum, and ileum was greater in HQC than LQC calves. A trend toward greater average daily gain was observed in HQC versus LQC calves (667 vs. 590 g/d) but the average daily gain was not influenced by collection time. Serum IGF-1 at d 4 was higher in HQC versus LQC calves and this might have contributed to greater average daily gain and small intestine development. Calves fed HQC had higher feed conversion ratios (FCR; total body weight gain/total dry matter intake) compared with LQC calves, and L calves had higher FCR compared with E calves. In conclusion, in comparison to feeding LQC, feeding HQC reduced the scouring duration, enhanced surface area of duodenum and jejunum, and improved FCR during the first 5 wk of calf age. Postpartum collection time of calves did not affect small intestine development, but L calves had higher FCR and required a lesser volume of electrolytes to treat scours compared with E calves during the first 35 d of life.

Heat treatment of bovine colostrum: II. Effects on calf serum immunoglobulin, insulin, and IGF-I concentrations, and the serum proteome

In-depth analysis of colostrum components has identified hundreds of proteins, but data are sparse regarding their systemic uptake in the newborn calf. Moreover, heat treatment may influence these colostral components and their absorption. Our objectives were to describe the serum proteome of newborn calves before and after colostrum feeding and the possible effects of colostral heat treatment. Newborn Holstein heifer calves (n = 22) were randomized within pair and fed heat-treated (n = 11; 60°C, 60 min) or raw (n = 11) colostrum at 8.5% of birth body weight by esophageal feeder within 1 h of birth. After the single colostrum feeding, calves were not fed until after the 8-h time point, when milk was offered free-choice. Blood samples were taken immediately before feeding (0 h), as well as 4, 8, and 24 h after feeding. Whole blood packed cell volume (%), serum Brix percentage, and plasma glucose concentrations were determined for all time points. Plasma insulin and insulin-like growth factor-I concentrations were determined by radioimmunoassay for selected time points. Serum IgA and IgG were measured by radial immunodiffusion at 24 h. The serum proteome was analyzed using nano-scale reverse-phase chromatography and tandem mass spectrometry (nano LC-MS/MS) in 0- and 8-h samples. For proteomics analysis, ratios of results for 8-h to 0-h samples were analyzed with false discovery rate adjustment. For all other outcomes, repeated-measures ANOVA was performed with the fixed effects of group, time, and their interaction, and random effect of pair. Serum Brix percentage and glucose concentrations increased over time and were independent of colostrum treatment. Serum IgG and IgA concentrations at 24 h did not differ between groups. Nano LC-MS/MS identified a total of 663 unique proteins in serum, of which 261 increased in abundance, whereas 67 decreased in abundance after feeding in both groups. Among serum proteins that increased in abundance and that were previously identified in colostrum, many belonged to those involved in immune response, coagulation, the classical complement pathway, or the antimicrobial peptide class of cathelicidins. Serum proteins that decreased in abundance and that were identified in colostrum belonged to the alternative complement pathway and the membrane attack complex. Thirty-eight proteins differed in calves that were fed heat-treated colostrum compared with those fed raw colostrum. Decreased abundances in calves fed heat-treated colostrum included several enzymes involved in glycolysis or glycogenolysis, whereas the incretin gastric inhibitory polypeptide and serum insulin were increased in this group. Our findings point to important innate immune defense pathways associated with colostrum ingestion in newborn calves. Furthermore, calves fed heat-treated colostrum showed differences in serum proteins and enzymes associated with carbohydrate metabolism.

Effects of dietary supplementation of Acanthopanax senticosus on gastrointestinal tract development in calves

Twenty-four newborn Holstein dairy male calves (with initial body weight of 38 ± 3.0 kg) were used in a randomized block design experiment to determine effects of dietary supplementation of Acanthopanax senticosus (AS) on gastrointestinal tract development. Calves were fed milk (10%/body weight) three times at 06.00, 12.00 and 18.00 hours daily with one to four treatments during the experimental periods (4 to 28 days): no supplementation of AS (control group, CG); 1.0 g/L•time of micro-powder AS (MP); 1.0 g/L•time of superfine powder AS (SP); or 1.0 g/L•time of coarse powder AS (CP). On days 7, 14, 21 and 28, 20 mL blood samples were collected at 06.00 hours before the morning feeding. At the end of the trial (28 days), all calves were euthanized, and tissue samples were taken and placed in 4% buffered formaldehyde for analyses. In the rumen of MP treatment, compared with the CG treatment, wall thickness and papillae diameter was both significantly lower (P<0.05), while crypt depth was significantly greater (P<0.05). In the duodenum, villi diameter of AS supplemented treatments was significantly lower than that of CG treatment (P<0.05). Results indicate that calves during sucking period supplemented with AS as MP style could promote gastrointestinal development.

Effects of Feeding Milk Replacer Ad Libitum or in Restricted Amounts for the First Five Weeks of Life on the Growth, Metabolic Adaptation, and Immune Status of Newborn Calves

The pre-weaning period is critical for calf health and growth, and intensive milk feeding programs may assist postnatal development by improving body growth and organ maturation. The aim of the present work was to study the effects of ad libitum milk replacer (MR) feeding on the growth, metabolic adaptation, health, and immune status of newborn calves. Twenty-eight newborn Holstein and Holstein x Charolais crossbred calves were fed ad libitum (ADLIB) or in restricted amounts (6 liters per day; RES) during the first five weeks of life. The MR intake in the ADLIB treatment was gradually reduced at weeks 6 and 7, and all calves then received 6 liters of MR per day until day 60. Blood samples were collected to measure the plasma concentrations of metabolites, insulin, insulin-like growth factor (IGF)-I and IGF binding proteins (IGFBP), immunoglobulins, and acute phase proteins. The expression of mRNA associated with both the somatotropic axis and gluconeogenic enzymes was measured in the liver on day 60. Intensive feeding improved MR intake and growth in ADLIB without influencing concentrate intake. Carcass weight, perirenal fat, and muscle mass were greater in ADLIB. Plasma concentrations of glucose, triglycerides, insulin, and IGF-I were greater, whereas plasma concentrations of β-hydroxybutyrate, total protein, albumin, urea, IGFBP-2 and -4, and fibrinogen were lower at distinct time points in ADLIB. The hepatic mRNA expression of cytosolic phosphoenolpyruvate carboxykinase was greater in ADLIB. Most metabolic and endocrine differences occurred during the MR feeding period, but a slightly greater concentrate intake was associated with increased plasma IGF-I and insulin at the end of the study. The immune and health status of the calves were not affected by MR feeding. However, increased plasma fibrinogen in the RES group suggested differences in the acute phase response.

Calves sucking colostrum and milk from their dams or from an automatic feeding station starting in the neonatal period: metabolic and endocrine traits and growth performance

Metabolic and endocrine traits and growth performance from birth up to day 28 in calves sucking colostrum and milk at a computer-programmed automatic feeding station (GrA, no. = 7) were compared with calves sucking their dams (GrS, no. = 7). Body weight tended to be higher on day 28 in GrS than in GrA (74 (s.e. 4) and 70 (s.e. 2) kg, respectively; P 0·1), but not weight gain from 0 to 28 days. Intakes in GrA increased from days 1 to 4 and then remained at 11·1 (s.e. 1·0) l/day. From days 2 to 11 calves visited the automatic feeding station 9 (s.e. 1) times per day. Plasma concentrations of urea (days 3 and 21), glucagon (day 3) and growth hormone (day 3) were higher in GrA than in GrS (P < 0·05), whereas plasma concentrations of total protein (days 1 to 28), immunoglobulin G (days 1 to 28), albumin (days 1 to 14), glucose (day 3), lactate (days 1 and 28), triglycerides (day 3), cholesterol (days 21 and 28), insulin (day 3), and insulin-like growth factor-1 (day 21) were lower in GrA than in GrS (P < 0·05). Metabolic and endocrine group differences were mainly seen in week 1. However, growth performance during the first 3 weeks of life was comparable in calves of the two groups but resulted in slightly enhanced body weight (by 4 ± 3·5 kg) at the end of the 1st month of life in GrS.

Invited review: Growth-promoting effects of colostrum in calves based on interaction with intestinal cell surface receptors and receptor-like transporters

The postnatal development and maturation of the gastrointestinal (GI) tract of neonatal calves is crucial for their survival. Major morphological and functional changes in the calf's GI tract initiated by colostrum bioactive substances promote the establishment of intestinal digestion and absorption of food. It is generally accepted that colostrum intake provokes the maturation of organs and systems in young calves, illustrating the significance of the cow-to-calf connection at birth. These postnatal adaptive changes of the GI tissues in neonatal calves are especially induced by the action of bioactive substances such as insulin-like growth factors, hormones, or cholesterol carriers abundantly present in colostrum. These substances interact with specific cell-surface receptors or receptor-like transporters expressed in the GI wall of neonatal calves to elicit their biological effects. Therefore, the abundance and activity of cell surface receptors and receptor-like transporters binding colostral bioactive substances are a key aspect determining the effects of the cow-to-calf connection at birth. The present review compiles the information describing the effects of colostrum feeding on selected serum metabolic and endocrine traits in neonatal calves. In this context, the current paper discusses specifically the consequences of colostrum feeding on the GI expression and activity of cell-receptors and receptor-like transporters binding growth hormone, insulin-like growth factors, insulin, or cholesterol acceptors in neonatal calves.

Relationship between serum iron and insulin-like growth factor-I concentrations in 10-day-old calves

Newborn calves are often deficient in iron and progressive reduction in blood iron concentration occurs over the first weeks of life. Some reports indicate the importance of interactions among iron and components of the insulin-like growth factor system. The aim of the study was to determine if there is a relationship between serum iron and insulin-like growth factor-I concentrations in neonatal calves. Blood samples were collected from 16 female Holstein-Friesian calves on day 10 of age. Erythrogram determination and measurements of serum iron, total protein, albumin, total iron binding capacity and serum insulin-like growth factor-I concentrations were performed. Haematological values were measured using an automatic analyzer, biochemical properties were determined spectrophotometrically, insulin-like growth factor-I concentration was measured by radioimmunoassay. Calves were divided into 2 groups according to iron concentrations; the first group of iron-deficient calves (n = 8, Fe < 10 μmol/l) and the second group of calves with optimal iron concentration (n = 8, Fe > 18 μmol/l). Blood indicators in all calves from the first group followed a pattern typically observed in anaemic calves. Insulin-like growth factor-I concentrations were significantly (P < 0.01) lower in the first group compared to the second group. However, insulin-like growth factor-I very strongly correlated with iron in calves from the second group compared to iron-deficient calves (r = 0.624; P < 0.01 and r = 0.478; P > 0.05, respectively). Based on our results, iron seems to have an important relationship to secretion of insulin-like growth factor-I in 10-day-old calves. This is the first report about such relationship in this age group of animals.

Lactation Biology Symposium: role of colostrum and colostrum components on glucose metabolism in neonatal calves

In neonatal calves, nutrient intake shifts from continuous glucose supply via the placenta to discontinuous colostrum and milk intake with lactose and fat as main energy sources. Calves are often born hypoglycemic and have to establish endogenous glucose production (eGP) and gluconeogenesis, because lactose intake by colostrum and milk does not meet glucose demands. Besides establishing a passive immunity, colostrum intake stimulates maturation and function of the neonatal gastrointestinal tract (GIT). Nutrients and nonnutritive factors, such as hormones and growth factors, which are present in high amounts in colostrum of first milking after parturition, affect intestinal growth and function and enhance the absorptive capacity of the GIT. Likely as a consequence of that, colostrum feeding improves the glucose status in neonatal calves by increasing glucose absorption, which results in elevated postprandial plasma glucose concentrations. Hepatic glycogen concentrations rise much greater when colostrum instead of a milk-based colostrum replacer (formula with same nutrient composition as colostrum but almost no biologically active substances, such as hormones and growth factors) is fed. In contrast, first-pass glucose uptake in the splanchnic tissue tended to be greater in calves fed formula. The greater plasma glucose rise and improved energy status in neonatal calves after colostrum intake lead to greater insulin secretion and accelerated stimulation of anabolic processes indicated by enhanced maturation of the postnatal somatotropic axis in neonatal calves. Hormones involved in stimulation of eGP, such as glucagon and cortisol, depend on neonatal diet, but their effects on eGP stimulation seem to be impaired. Although colostrum feeding affects systemic insulin, IGF-I, and leptin concentrations, evidence for systemic action of colostral insulin, IGF-I, and leptin in neonatal calves is weak. Studies so far indicate no absorption of insulin, IGF-I, and leptin from colostrum in neonatal calves, unlike in rodents where systemic effects of colostral leptin are demonstrated. Therefore, glucose availability in neonatal calves is promoted by perinatal maturation of eGP and colostrum intake. There may be long-lasting effects of an improved colostrum supply and glucose status on postnatal growth and development, and colostrum supply may contribute to neonatal programming of performance (milk and growth) in later life, but data proving this concept are missing.

Energy metabolism in the newborn farm animal with emphasis on the calf: endocrine changes and responses to milk-born and systemic hormones

Neonatal mammals need adaption to changes in nutrient supply because energy intake shifts from continuous parenteral supply of nutrients (mainly glucose, lactate, and amino acids) via the placenta to discontinuous colostrum and milk intake with lactose and fat as main energy sources. Besides ingested lactose, endogenous glucose production is essential in the neonate to assure sufficient glucose availability. Fetal endogenous glucose production is low, but endocrine changes (especially the prenatal rise of glucocorticoid production) promote maturation of metabolic pathways that enable marked glycogen synthesis before and enhanced gluconeogenesis after birth to establish an adequate glucose status during postnatal maturation. In preterm born farm animals gluconeogenic activity is low, mainly because of a low glucocorticoid and thyroid status. In full-term neonates, endogenous glucose production increases with age. Colostral bioactive components (such as growth factors, hormones, bioactive peptides, and cytokines) do not have a direct effect on endogenous glucose production. However, colostrum feeding stimulates intestinal growth and development, an effect at least in part mediated by bioactive substances. Increased nutrient and glucose absorption thus allows increased glucose supply and hepatic glycogen storage, which improves the glucose status. The improved energetic status of colostrum-fed neonates is reflected by an accelerated maturation of the somatotropic axis, leading especially to enhanced production of IGF-I in the neonate. Secretion and production of hormones involved in the regulation of glucose and fat metabolism in neonates depend on the developmental stage and the response to feeding. In addition, many such hormones have actions in the neonate that differ from adult animals. Endocrine action to support endogenous energy supply in neonates is probably not fully established, and therefore, needs postnatal maturation. Therefore, our knowledge on energy metabolism in the neonate needs to be extended to better understand the function and the failure and to assess endocrine responses during the neonatal period.

Insulin-like growth factors (IGFs), IGF binding proteins, and other endocrine factors in milk: role in the newborn

The role of colostrum and milk in the neonate has been chiefly recognized as a comprehensive nutrient foodstuff. In addition, the provision of colostrum-the first milk-for early immune capacity has been well documented for several species. Colostrum is additionally a rich and concentrated source of various factors that demonstrate biological activity in vitro. Three hypotheses have been proposed for the phenotypic function of these secreted bioactive components: (1) only mammary disposal, (2) mammary cell regulation, and (3) neonatal function [gastrointestinal tract (GIT) or systemic]. Traditionally, it was assumed that the development of the GIT is preprogrammed and not influenced by events occurring in the intestinal lumen. However, a large volume of research has demonstrated that colostrum (or milk-borne) bioactive components can basically contribute to the regulation of GIT growth and differentiation, while their role in postnatal development at physiological concentrations has remained elusive. Much of our current understanding is derived from cell culture and laboratory animals, but experimentation with agriculturally important species is taking place. This chapter provides an overview of work conducted primarily in neonatal calves and secondarily in other species on the effects on neonates of selected peptide endocrine factors (hormones, growth factors, in part cytokines) in colostrum. The primary focus will be on insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) and other bioactive peptides, but new interest and concern about steroids (especially estrogens) in milk are considered as well.

Nutritional physiology of neonatal calves*

The gastrointestinal tract of neonatal calves is relatively mature but still requires morphological and functional changes. The intake of colostrum with its nutrient and non-nutrient components exerts marked effects on gastrointestinal development and function. Colostrum intake provides immunoprotection (passive immunity by immunoglobulins) and is essential for survival of neonates of most species. Furthermore, there are important transient as well as long-lasting systemic effects on the nutritional status, on metabolism, and on various endocrine systems due to intake of nutrient and non-nutrient colostral components that contribute to survival in the stressful postnatal period. Colostrum is much more than just a supplier of immunoglobulins.

EFFECT OF ZINC SULPHATE AND ZINC METHIONINE ON GROWTH, PLASMA GROWTH HORMONE CONCENTRATION, GROWTH HORMONE RECEPTOR AND INSULIN-LIKE GROWTH FACTOR-I GENE EXPRESSION IN MICE

1. The current experiment was conducted to investigate the effect of zinc sulphate (ZnSO4) and zinc methionine (Zn-Met) on growth and their effect on plasma growth hormone (GH) concentration, growth hormone receptor (GHR) and insulin-like growth factor I (IGF-I) mRNA expression in mice. 2. Ninety male KunMing (KM) mice were randomly divided into three treatments. The control group was fed on a basal diet containing 11.67 mg/kg of zinc. The ZnSO4 group and Zn-Met group were fed on the diets supplemented with ZnSO4 or Zn-Met at 30 mg/kg (containing zinc of 40.05 and 40.75 mg/kg, respectively). The mice were offered the test diets for 10 days. Weight gains and food intake were measured at the end of the experiment, zinc contents in liver and serum were determined using atomic absorption spectrophotometry; GH was determined by radioimmunoassay, the levels of GHR and IGF-I mRNA were determined with reverse transcript polymerase chain reaction. 3. Both ZnSO4 and Zn-Met enhanced weight gain and food intake in the mice, Zn-Met improved the growth and food intake more effectively than ZnSO4 did (P < 0.05). The both forms of zinc had no effect on GH and the level of GHR mRNA expression (P > 0.05) and they up-regulated the expression of IGF-I mRNA (P < 0.05). As compared to ZnSO4, Zn-Met enhanced the level of IGF-I mRNA significantly (P < 0.05). 4. Both ZnSO4 and Zn-Met had no effect on plasma GH and the expression of GHR mRNA, but they enhanced the expression of IGF-I mRNA. Zinc methionine enhanced the weight gain and up-regulated IGF-I mRNA expression more effectively than ZnSO4.

Effects of colostrum feeding and dexamethasone treatment on mRNA levels of insulin-like growth factors (IGF)-I and -II, IGF binding proteins-2 and -3, and on receptors for growth hormone, IGF-I, IGF-II, and insulin in the gastrointestinal tract of neonatal calves

The somatotropic axis regulates growth of the gastrointestinal tract (GIT). In addition, colostrum feeding and glucocorticoids affect maturation of the GIT around birth in mammals. We have measured mRNA levels of members of the somatotropic axis to test the hypothesis that colostrum intake and dexamethasone treatment affect respective gene expression in the GIT. Calves were fed either colostrum or an isoenergetic milk-based formula, and in each feeding group, half of the calves were treated with dexamethasone (DEXA; 30 microg/kg body weight per day). Individual parameters of the somatotropic axis differed (P < 0.05) among different GIT sections and formula feeding increased (P < 0.05) mRNA levels of individual parameters at various sites of the GIT. Effects of DEXA on the somatotropic axis in the GIT partly depended on different feeding. In colostrum-fed calves, DEXA decreased (P < 0.05) mRNA levels of IGF-I (esophagus, fundus, duodenum, and ileum), IGF-II (fundus), IGFBP-2 (fundus), IGFBP-3 (fundus), IGF1R (esophagus, ileum, and colon), IGF2R (fundus), GHR (fundus), and InsR (esophagus, fundus), but in formula-fed calves DEXA increased mRNA levels of IGF-I (esophagus, rumen, jejunum, and colon). Furthermore, DEXA increased (P < 0.05) mRNA levels of IGF-II (pylorus), IGFBP-3 (duodenum), IGF2R (pylorus), and GHR (ileum), but decreased mRNA levels of IGFBP-2 (ileum), and IGF1R (fundus). Whereas formula feeding had stimulating effects, effects of DEXA treatment on the gene expression of parameters of the somatotropic axis varied among GIT sites and partly depended on feeding.

Abundance of message for insulin-like growth factors-I and -II and for receptors for growth hormone, insulin-like growth factors-I and -II, and insulin in the intestine and liver of pre- and full-term calves

The somatotropic axis and insulin are involved in pre- and postnatal development. In pre- and full-term calves (GrP0 and GrN0; born after 277 and 290 d of pregnancy, respectively) and in preterm calves on d 8 of life after being fed for 7 d (GrP8), we studied whether there are differences in the abundance of messenger RNA (mRNA) of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II, and insulin among different intestinal sites (duodenum, jejunum, ileum, and colon) and whether there are ontogenetic differences during the perinatal period in intestine and liver. Intestinal site differences (P < 0.05) existed in mRNA levels of IGF-I and IGF-II and receptors for GH, IGF-I, IGF-II, and insulin. Abundance of mRNA of IGF-I and -II and of receptors for IGF-I and GH was highest (P < 0.05) in the colon, abundance of the receptor for IGF-II was comparably high in the colon and ileum, and that of the receptor for insulin was similarly high in colon, ileum, and jejunum. Among GrP0, GrN0, and GrP8 groups, there were differences (P < 0.05) in mRNA levels of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II and insulin. Abundance of mRNA of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II and insulin was highest (P < 0.05) in GrP0 calves immediately after birth and was primarily seen in the ileum. In liver, the mRNA levels differed (P < 0.05) among groups for IGF-II and receptors for IGF-I, IGF-II, and insulin, and were highest (P < 0.05) for IGF-II in GrP0, for receptors of IGF-I in GrN0, and were higher (P < 0.05) in GrP0 than GrP8 for receptors of IGF-II. In conclusion, mRNA levels of IGF-I and IGF-II and of receptors for GH, IGF-I, IGF-II, and insulin were different at different intestinal sites and in intestine and liver and changed during the perinatal period.

Effects of dexamethasone and colostrum intake on the somatotropic axis in neonatal calves

Glucocorticoids and colostrum feeding influence postnatal maturation of the somatotropic axis. We have tested the hypothesis that dexamethasone (Dexa) affects the somatotropic axis in neonatal calves dependent on colostrum intake. Calves were fed either with colostrum or with a milk-based formula (n = 14/group), and, in each feeding group, one-half of the calves were treated with Dexa (30 micro g. kg body wt-1. day-1). Pre- and postprandial blood samples were taken on days 1, 2, 4, and 5, and liver samples were taken on day 5 of life. Dexa increased insulin-like growth factor (IGF)-I, but decreased growth hormone (GH) and IGF-binding protein (IGFBP)-1 and -2 plasma concentrations and increased GH receptor (GHR) mRNA levels in liver. Dexa increased IGF-I mRNA levels only in formula-fed calves and increased hepatic GHR binding capacity, but only in colostrum-fed calves. Colostrum feeding decreased IGFBP-1 and -2 plasma concentrations and hepatic IGFBP-2 and -3 mRNA levels. In conclusion, Dexa and colostrum feeding promoted maturation of the somatotropic axis. Dexa effects partly depended on whether colostrum was fed or not.

Effect of photoperiod on hepatic growth hormone receptor 1A expression in steer calves

Photoperiod manipulation, specifically a long-day photoperiod (LDPP), increases milk production in lactating cattle. We have previously reported that the galactopoietic effect of LDPP is associated with an increase in circulating IGF-I, which seems to occur independently of changes in concentrations of GH, IGFBP-2, and IGFBP-3. This study tested the hypothesis that LDPP increases the expression of GH receptor (GHR) 1A messenger RNA (mRNA) in the liver. Two groups of Holstein steer calves (98 +/- 4 d old) were maintained indoors and exposed to LDPP (16-h light: 8-h dark; n = 6) or short-day photoperiod (SDPP; 8-h light: 16-h dark; n = 6) for 60 d. Calves were individually fed a grain- and alfalfa-based diet. Jugular blood samples were collected weekly and via cannula at 15-min intervals for a 4-h period on d 1, 26, and 55 of the study to monitor pulsatile hormone secretion. Serum was harvested and assayed for IGF-I, prolactin (PRL), and GH using RIA. Liver biopsies were obtained at 3-wk intervals to quantify changes in hepatic IGF-I and GHR 1A mRNA using real-time PCR. Steer BW increased during the study but did not differ between treatments. No differences in ADG or total DMI were observed. Relative to SDPP, calves on LDPP had higher (P < 0.05) serum IGF-I concentrations. Concentrations of PRL increased (P < 0.01) in calves exposed to LDPP compared with calves exposed to SDPP. Differences (P < 0.05) in pulsatile GH secretion were also detected. Hepatic IGF-I and GHR 1A mRNA were positively correlated with circulating IGF-I concentrations, and although both increased with time, they were not affected by photoperiod treatment. These results confirm that LDPP increases circulating concentrations of IGF-I, but this occurs independently of changes in IGF-I synthesis and GHR 1A mRNA expression in the liver. Therefore, our hypothesis that LDPP increases the expression of GHR 1A mRNA in the bovine liver is rejected.

Intestinal morphology, epithelial cell proliferation, and absorptive capacity in neonatal calves fed milk-born insulin-like growth factor-I or a colostrum extract

Concentrations of nonnutritional factors, such as insulin-like growth factor-I (IGF-I), in bovine colostrum are high and can modulate neonatal gastrointestinal tract development and function. In neonatal calves, we have investigated effects on intestinal epithelial cell morphology, proliferation, and absorption of feeding milk-born human IGF-I (hIGF-I) or a bovine colostrum extract. Calves were fed a milk-based formula containing amounts of nutrients comparable to colostrum for the first 3 d and a milk replacer from d 4 on. Formula and milk replacer contained only traces of nonnutritional factors. In experiment 1, supraphysiological amounts of hIGF-I (3.8 mg/L formula; secreted by transgenic rabbits with their milk) were added to the formula. Xylose appearance in blood (after feeding xylose on d 5) and intestinal traits (after euthanasia on d 8) did not differ between groups. In experiment 2, an extract of first-milked bovine colostrum that provided physiological amounts of IGF-I (0.50, 0.15, and 0.09 mg of IGF-I/L formula on d 1, 2, and 3, respectively, and 0.09 mg of IGF-I/L milk replacer on d 4) was added to formula or milk replacer. Plasma xylose concentration in the control group was transiently higher than in calves fed the colostrum extract. On d 5 (after euthanasia), villus circumferences and heights in small intestine, and epithelial cell proliferation rate in intestine were higher in calves fed the colostrum extract than in controls. In conclusion, orally administered hIGF-I from transgenic rabbits had no effect on the intestinal tract. However, feeding a bovine colostrum extract enhanced intestinal villus size, although it appeared to transiently decrease the absorptive capacity.

Feed intake patterns, growth performance, and metabolic and endocrine traits in calves fed unlimited amounts of colostrum and milk by automate, starting in the neonatal period

Feed intake, growth performance, and metabolic and endocrine traits were studied in male calves fed unlimited (GrAL; n = 7) amounts of colostrum for 3 d after birth and mature milk up to d 28 and were compared with calves fed commonly recommended amounts of colostrum and milk (GrRS; n = 7). Calves were fed by automates, and software was available to continuously register the time points and amounts of ingested feed up to 11 d of age. Body weight was measured on d 1, 4, 7, 14, 21, and 28, and blood samples were taken on d 1, 2, 3, 7, 14, 21, and 28 to measure several metabolites and hormones. Feed intake of calves fed GrAL increased from d 1 to 4, then remained stable and was always higher than for calves fed GrRS. Total visits (visits with and without milk intake) were higher for GrRS than GrAL, but visits with milk intake were comparable between groups and meal sizes per visit with milk intake were greater in GrAL than in GrRS. Body weight gain was greater in GrAL than in GrRS in wk 1, but not later. There were significant group differences in plasma concentrations of albumin (GrRS > GrAL), nonesterified fatty acids (GrRS > GrAL), cholesterol (GrRS > GrAL; d 28), insulin (GrAL > GrRS), and cortisol (GrRS > GrAL), but not of immunoglobin G, urea, glucose, triglycerides, growth hormone, and glucagon. In conclusion, calves fed ad libitum were capable of ingesting very large amounts of colostrum and milk, even during wk 1 of life, accompanied by a greater body weight gain in GrAL in the first week, whereas in GrRS, the high number of visits without feed intake indicate that these calves reached no repletion. Compared with calves provided restricted amounts of feed, calves with free access to colostrum and milk were characterized by reduced plasma concentrations of nonesterified fatty acids and by a transiently enhanced insulin and reduced cortisol status.

Colostral and milk insulin-like growth factors and related substances: mammary gland and neonatal (intestinal and systemic) targets

The identification of hormones and regulatory factors in colostrum and milk has led to intensive investigations on their roles in the development and maintenance of the mammary and neonatal tissues. Insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in transgenic mice influence mammary biology gland towards the end of lactation. In the bovine, IGFBP-3 is the major IGFBP in mammary secretions. In addition to binding IGFs, IGFBP-3 also binds to lactoferrin (Lf). Secreted IGFBP-3 re-enters mammary epithelial cells and with the presence of a nuclear localization sequence, IGFBP-3 and Lf enter the nucleus. Nuclear IGFBP-3 affects apoptotic signaling through the retinoic-x-receptors, while Lf affects apoptotic events through unknown mechanisms. Such interactions likely influence mammary development and involution. Furthermore, ingested colostral bioactive factors can exert regulatory functions in neonates. Intestinal receptors for IGFs and insulin are modified by age and/or diet. Feeding IGF-I had no effect, but colostrum extracts had small intestinal effects (stimulation of proliferation and villus size), suggesting that several factors, rather than one single bioactive factor were responsible. Systemic changes of metabolic and endocrine profiles in neonates depend on composition, amounts, time and duration of feeding colostrum. Early postnatal colostrum intake is not only important for the provision and absorption of immunoglobulins. Thus, in neonatal calves the lack of colostrum intake during the first 24h after birth results in a low immunoglobulin G, beta-carotene and Vitamin A status that persists for weeks and plasma patterns of fatty acids, essential amino acids and the glutamine/glutamate ratios are affected. In calves oral administration of IGF-I had no and feeding of colostrum whey extracts had only minor effects on metabolic and endocrine traits. Thus, mammary secretions influence regulatory functions of mammary and neonatal tissues.

Feeding different amounts of colostrum or only milk replacer modify receptors of intestinal insulin-like growth factors and insulin in neonatal calves

Colostrum intake influences growth and development of the gastrointestinal tract (GIT) in several species and colostral insulin-like growth factors I and II (IGF-I and IGF-II), and insulin are involved in neonatal intestinal tissue growth. We have studied IGF type 1, IGF type 2, and insulin receptors in the intestine of 8-day-old calves fed different amounts of colostrum or only milk replacer. Calves were fed colostrum of the first six milkings on the first 3 days and then milk replacer (GrC(6)) or colostrum only once and then milk replacer (GrC(1)) or they were fed only milk replacer from the beginning, i.e., no colostrum (GrM). Competitive binding studies and ligand blots confirmed the presence of IGF type 1, IGF type 2, and insulin receptors in mucosal cell membranes of duodenum, jejunum, ileum, and colon. The IGF type 1 receptor number in ileum and total intestine in GrC(6) was greater (P<0.05) than in GrC(1) and in GrM, and IGF type 2 receptor number in total intestine was greater (P<0.05) in GrC(6) than in GrM. Insulin binding was best fitted by a model with two binding sites. High affinity insulin receptor numbers in duodenum, ileum, and total intestine were greater (P<0.05) in GrC(6) than in GrM. The data demonstrate that IGF type 1, IGF type 2, and insulin receptors in intestinal mucosa of neonatal calves are influenced by feeding.

Real-time RT-PCR quantification of insulin-like growth factor (IGF)-1, IGF-1 receptor, IGF-2, IGF-2 receptor, insulin receptor, growth hormone receptor, IGF-binding proteins 1, 2 and 3 in the bovine species

Reverse transcription (RT) followed by polymerase chain reaction (PCR) is the technique of choice for analysing mRNA in extremely low abundance. Real-time RT-PCR using SYBR Green I detection combines the ease and necessary exactness to be able to produce reliable as well as rapid results. To obtain highly accurate and reliable results in a real-time RT-PCR a highly defined calibration curve is needed. We designed and developed nine different calibration curves, based on recombinant DNA plasmid standards and established them on a constant real-time PCR platform for the following factors: growth hormone receptor (GHR), insulin-like growth factor (IGF)-1, IGF-1 receptor (IGF-1R), IGF-2, IGF-2 receptor (IGF-2R), insulin receptor (INSR), and IGF-binding proteins (IGF-BP) 1, 2 and 3. Developed assays were applied in the LightCycler system on bovine ileum and liver total RNA and showed high specificity and sensitivity of quantification. All assays had a detection limit of under 35 recombinant DNA molecules present in the capillary. The SYBR Green I determination resulted in a reliable and accurate quantification with high test linearity (Pearson correlation coefficient r > 0.99) over seven orders of magnitude from <10(2) to >10(8) recombinant DNA start molecules and an assay variation of maximal 5.3%. Applicability of the method was shown by analysing mRNA levels in newborn calves: mRNA concentrations per gram tissue of mRNAs of IGF-1, IGF-1R, IGF-2, IGF-2R, GHR, INSR, and IGF-BP1, 2 and 3 were all different between in liver and ileum and the traits all exhibited individual differences.

Feeding colostrum, its composition and feeding duration variably modify proliferation and morphology of the intestine and digestive enzyme activities of neonatal calves

We studied the effects of amounts of colostrum consumed on intestinal morphology and proliferation and digestive enzyme activities in neonatal calves. Group GrCmax calves were fed colostrum from the first milking undiluted on d 1-3 and diluted with 25, 50, 75 and 75 parts of a milk replacer on d 4-7. Group GrC1-3 calves were fed colostrum from milkings 1-6 up to d 3 and then a milk replacer up to d 7. Group GrF1-3 calves were fed a milk-based formula (containing only traces of growth factors and hormones) up to d 3 and then a milk replacer up to d 7. Calves were killed on d 8. Differences in feeding affected villus sizes and villus height/crypt depth ratios in the duodenum (GrCmax > GrC1-3), villus areas and villus height/crypt depth ratios in the jejunum (GrC1-3 > GrF1-3) and crypt depths in the colon (GrF1-3 > GrC1-3). Furthermore, different feeding protocols affected the proliferation rates of epithelial cells in the duodenum (GrC1-3 > GrCmax; GrC1-3 > GrF1-3) and the jejunum (GrF1-3 > GrC1-3; based on Ki-67 labeling). Lipase activities in the pancreas were influenced by colostrum feeding (GrC(max) > GrC(1-3)). Colostrum intake differentially affected intestinal epithelial surface and proliferation and enzyme activities. Feeding high amounts of first colostrum seemed to enhance the survival of mature mucosal epithelial cells in selected parts of the small intestine, whereas the lack of colostrum seemed to decrease epithelial growth.