Jan Elnif

Preterm Birth Affects the Intestinal Response to Parenteral and Enteral Nutrition in Newborn Pigs

Maturation of gastrointestinal (GI) function in neonates is stimulated by enteral nutrition, whereas parenteral nutrition induces GI atrophy and malfunction. We investigated whether preterm birth alters the GI responses to parenteral and enteral nutrition. Pigs were delivered either preterm (107 d gestation) or at term (115 d gestation) and fed total parenteral nutrition (TPN) or enteral sows milk (ENT) for 6 d after birth. Immaturity of the preterm pigs was documented by reduced blood pH, oxygen saturation and neutrophil granulocyte function, impaired intestinal immunoglobulin G uptake from colostrum, and altered relative weights of visceral organs (small intestine, liver, spleen, pancreas, and adrenals). For both ages at delivery, increases occurred in pancreatic weight (30-75%) and amylase activity (0.5- to 13-fold) after birth, but much more in ENT than in TPN pigs (P < 0.05). Six days of TPN feeding was associated with reduced intestinal weight for both delivery groups (60% of values in ENT, P < 0.001), but only in term TPN pigs was the weight lower than at birth (-20%, P < 0.05). Likewise, it was only in term TPN pigs that intestinal maltase activity increased, compared with ENT, and the absorption of glucose and proline decreased. Only in preterm pigs did TPN feeding increase lactase activity (+50% compared with ENT, P < 0.05). For both delivery ages, the mRNA of lactase-phloridzin hydrolase and sodium-coupled glucose transporter 1 (SGLT-1) were increased in TPN, compared with ENT. In conclusion, the trophic effect of enteral vs. parenteral nutrition on the GI tract is also present after preterm birth, but the postnatal maturation of many GI functions is modified, compared with term birth. The effects of nutritional regimen on the maturation of the gut epithelium in neonates depend on gestational age at birth.

Glucagon-like peptide 2 enhances maltase-glucoamylase and sucrase-isomaltase gene expression and activity in parenterally fed premature neonatal piglets.

Exogenous glucagon-like peptide 2 (GLP-2) mimics the stimulatory effect of enteral nutrition on intestinal mucosal growth in preterm neonatal pigs. Little is known about its effects on small intestinal function. In this study, we investigated whether the trophic actions of GLP-2 and enteral nutrition are paralleled by effects on small intestinal function. Cesarean-delivered piglets (92% of gestation) were given either a parenteral nutrient infusion [total parenteral nutrition (TPN), n = 7], TPN + human GLP-2 (25 nmol/kg/d, n = 8), or enteral nutrition (ENT, n = 6) for 6 d. Gene expression (mRNA) and activities of lactase phlorizin hydrolase (LPH), maltase-glucoamylase (MGA), sucrase-isomaltase (SI), aminopeptidase N (ApN), and A (ApA) and dipeptidyl peptidase IV (DPP IV) were measured. Both GLP-2 and enteral nutrition increased mucosal weight (+30–40%, p < 0.05) relative to TPN. GLP-2 stimulated jejunal MGA and SI mRNA abundance and activity levels but did not change LPH in parenterally fed pigs (p < 0.05). Enteral nutrition decreased jejunal LPH and MGA mRNA abundance and activity and increased ileal ApN, ApA, and DPP IV activities relative to TPN (p < 0.05). We conclude that GLP-2 and enteral nutrition exert different effects on intestinal enzyme function despite similar effects on intestinal growth. In addition, the effects of GLP-2 on intestinal function in these parenterally fed, premature neonatal pigs differed from those previously reported for similarly fed term neonates.

Glucagon-like peptide 2 stimulates intestinal nutrient absorption in parenterally fed newborn pigs.

Objectives: Parenteral nutrition is a critically important intervention for children with intestinal dysfunctions. However, total parenteral nutrition (TPN) with no enteral feeding is associated with small intestine atrophy and malabsorption, which complicate the transition to enteral nutrition. The objective of the present study was to evaluate the therapeutic potential of the intestinotrophic peptide glucagon-like peptide 2 (GLP-2), which reduces TPN-associated atrophy and maintains nutrient absorption in adult rats, for preventing nutrient malabsorption in neonates receiving TPN. Methods: Term pigs obtained by cesarean delivery received from birth TPN alone (TPN; n = 7) or TPN with GLP-2 (25 nmol · kg−1 · d−1; GLP-2; n = 8) or were fed sow milk enterally (n = 7). The small intestine was removed on postnatal day 6 to measure morphological responses and absorption of glucose, leucine, lysine and proline by intact tissues and brush border membrane vesicles and to quantify the abundances of mRNA and protein for enterocyte glucose transporters (SGLT-1 and GLUT2). Results: Relative to TPN alone, administration of GLP-2 resulted in small intestines that were larger (P < 0.01), had greater abundances of mRNA and protein for SGLT-1, but not for GLUT2, and had higher capacities to absorb nutrients (P < 0.01). Moreover, the intestines of GLP-2 pigs were comparable in size and absorptive capacities with those of pigs fed sow milk enterally. Conclusions: Providing GLP-2 to neonates receiving TPN prevents small intestine atrophy, results in small intestine absorptive capacities that are comparable to when nutrients are provided enterally and may accelerate the transition from TPN to enteral nutrition.

Effect of silver nanoparticles on growth performance, metabolism and microbial profile of broiler chickens

This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, repectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0.03) was increased, but N excretion and efficiency of utilisation was not affected. The populations of bacteria in the intestinal samples were not affected by AgNano supplementation. The concentration of immunoglobulin (IgG) in the blood plasma of broilers supplemented with AgNano decreased at day 36 (p = 0.012). The results demonstrated that AgNano affects N utilisation and plasma IgG concentration; however, it does not influence the microbial populations in the digestive tract, the energy metabolism and growth performance of chickens.

Effect of nanoparticles of silver and gold on metabolic rate and development of broiler and layer embryos

This investigation evaluated the effects of nanoparticles of silver (AgNano) and gold (AuNano) on metabolic rate (O(2) consumption, CO(2) production and heat production-HP) and the development of embryos from different breeds of broiler and layer chicken. Gaseous exchange was measured in an open-air-circuit respiration unit, and HP was calculated for 10, 13, 16 and 19-day-old embryos. Relative chick and muscle weights were used as a measure of growth rate and development. AgNano but not AuNano increased the rates of O(2) consumption and HP of the layer embryos. The metabolic rate of broiler embryos was not affected by either of the treatments, but it was significantly higher compared to the layer embryos. Neither of the nanoparticles promoted nor depressed growth and development of the embryos, irrespective of breed. Although the metabolic rate of AgNano-injected layer embryos was significantly increased, their BW and muscle weights at hatching were similar to those of the control group, which suggests that the concentration of AgNano used was adequate for increasing the metabolic rate but not enough to affect growth and development. The results show that AgNano could be a potential metabolic modifier for layer embryos; however, the exact mechanism of action should be elucidated in future research.

Effects of feeding and short-term fasting on water and electrolyte turnover in female mink ( Mustela vison )

Daily (24 h) rates of water and electrolyte turnover were measured in a conventional balance study in ten adult female pastel mink (Mustela vison) given free access to a standard mink feed for a 1-week conditioning period, followed by a 4 d experimental period and a 2 d fasting period. Drinking water was available throughout. In addition, the completeness of urine collection and the fraction of urine collected with the faeces were determined using a new experimental technique based on 24 h recoveries of specific urinary markers such as tritiated p-aminohippuric acid ([3H]PAH) or 14C-labelled inulin ([14C]IN) continuously delivered by small Alzet osmotic pumps implanted intraperitoneally. During feeding the mean individual percentage recovery in urine of [3H]PAH released from the osmotic pumps ranged from 68 to 88% (median 78%). The mean percentage of urinary [3H]PAH recovered from faecal collections was 6% (range 3-12%). In response to fasting the mean individual percentage recovery of [3H]PAH in urine ranged from 62 to 78% (median 68%). For urinary [14C]IN the mean percentage recoveries in fed and fasted animals were 79 and 63% respectively. Furthermore, during fasting, withdrawal of the supplies of dietary water caused a slight but insignificant (P = 0.17) increase in the daily intake of drinking water and, hence, the animals maintained their normal water balance by a dramatic reduction in urine excretion (P < 0.001). At the same time urinary solute excretion declined significantly (P < 0.001), due in part to the cessation of dietary electrolyte intake and in part to reduced formation of urea, whereas urinary osmolality decreased only moderately. The mean 24 h balances of Na, K, Ca, Mg, Cl and P were close to zero and only minor differences between the feeding and fasting periods were observed. When corrected for the measured inaccuracies in urine collection the balance data obtained in the present study represent useful reference standards for normally fed and fasted non-growing mink and, to some extent, useful guidelines for future studies in experimental animals.

Nitrogen balance in adult female mink ( Mustela vison ) in response to normal feeding andshort-term fasting

Ten adult female mink (Mustela vison) were studied in a 7 d balance experiment consisting of a 2 d pre-surgery feeding period, followed by surgery, 1 d of recovery 4 d of ad libitum feeding, and a 2 d fasting period. In this experiment (Expt A) the animals had osmotic pumps implanted for continuous release of radioactively-labelled p-aminohippuric acid (p-aminobenzoyl-2-[3H]glycine; [3H]PAH; n 10) and 14C-labelled inulin ([14C]IN; n 5). Repeated 24 h collections of urine, corrected to 100% [3H]PAH or [14C]IN recovery, were used for accurate determination of N balances, 24 h urinary excretion of urea, creatinine, and total N, and calculation of mean 24 h renal clearance rates for endogenous creatinine and inulin. N balances were slightly below zero, but not significantly different between feeding and fasting periods, indicating that correction to 100% [3H]PAH recovery resulted in slight overestimation of the final balances. During fasting, withdrawal of the dietary water and protein loads resulted in a dramatic decline in 24 h urinary volume, and urea and creatinine excretion. Large individual variations in 24 h urinary creatinine excretion (with relative variation coefficients up to 30%) confirmed that this is an unreliable index of the completeness of urine collection. In this respect, recovery rates of [3H]PAH proved far more consistent. Renal clearance values obtained in fed mink were in fair agreement with published data from cats, dogs and ferrets (Mustela putorius furo). Inulin clearance was about 30% higher than endogenous creatinine clearance, although its decline in response to fasting was not significant. In a separate study (Expt B) another ten female mink were equipped with osmotic pumps containing [3H]PAH for determination of 24 h excretion rates of purine derivatives. During feeding, allantoin accounted for more than 97% of the excretion of purine derivatives in urine, uric acid making up less than 2.5%, xanthine and hypoxanthine less than 1%. In fasted animals, urinary excretion of each of these purine derivatives declined to less than 50% of the feeding value. In conclusion, an experimental technique is presented for efficient and accurate measurements of daily urinary excretion of nitrogenous constituents, which allows for correct determination of N balances in adult mink and, presumably, in other mammalian species.

Influence of in ovo injection and subsequent provision of silver nanoparticles on growth performance, microbial profile, and immune status of broiler chickens

Correspondence: Andre Chwalibog University of Copenhagen, Department of Veterinary Clinical and Animal Sciences, Gronnegardsvej 3, 1870 Frederiksberg C, Denmark Tel +45 3533 3044 Fax +45 3533 3020 Email ac@life.ku.dk Background: Because of their unique biological properties and strong antimicrobial activity, silver nanoparticles have received considerable attention and been used widely in an increasing number of consumer and medical products. In the present study, the potential of silver nanoparticles as an alternative antimicrobial growth-promoting supplement for broiler chickens was investigated. Methods: On day 1 of incubation, two groups of fertile eggs were injected with colloidal silver nanoparticles 10 mg/kg or 20 mg/kg. A third group was not injected and designated as a control group. At day 7 post-hatching, drinking water containing three silver nanoparticle concentrations (0, 10, and 20 mg/kg) was offered for 4 weeks. Body weight and feed consumption were measured weekly. At days 22 and 36, blood samples and intestinal contents were collected to evaluate the effects of the silver nanoparticles on plasma concentrations of immunoglobulins (IgG and IgM) and intestinal microflora. Results: In ovo injection of silver nanoparticles 10 mg/kg and 20 mg/kg and subsequent provision in the drinking water during the post-hatch period reduced feed intake by about 5.0 g/day (P = 0.02) and body weight by about 41.0 g (P = 0.001); however, no concurrent effect on feed conversion ratio was observed. Bacterial populations in the ileum were not affected. Numbers of lactose-negative enterobacteria and lactic acid bacteria decreased in the cecum (P , 0.05). Silver nanoparticle supplementation increased the concentration of acetic acid (P = 0.006), but not the concentrations of butyric, propionic, valeric, and succinic acid in the cecum. No treatment effects on plasma concentrations of IgG and IgM were noted. Conclusion: Silver nanoparticles affect feed intake, acetic acid concentration, numbers of lactosenegative and lactic acid bacteria, and immunoglobulin levels in broiler chickens. Silver nanoparticles are a potent antimicrobial agent for use in these birds. However, their activity and impact on growth performance should be explored further in a commercial poultry production setting.

Investigating the Effect of In Ovo Injection of Silver Nanoparticles on Fat Uptake and Development in Broiler and Layer Hatchlings

Silver nanoparticles (AgNano) as carrier of available oxygen (O2) and with high surface reactivity may increase O2 consumption, enhance fat uptake (FU), and stimulate growth and development. The objective was to investigate the effects of in ovo injection of AgNano on the metabolic rate (O2 consumption, CO2 production, and heat production, HP), fat uptake, and the development of broiler and layer hatchlings. AgNano concentrations (50, 75, and 100 mg/kg) were injected in ovo at day 1 of incubation to different breeds of broiler and layer chicken embryos. Oxygen consumption and subsequently FU did not increase linearly following AgNano treatment. FU was lower in hatchlings treated with 50 and 100 mg AgNano/kg, but surprisingly not in hatchlings treated with 75 mg AgNano/kg. Interestingly, the difference in FU between treatments was not reflected in hatchling development. The results indicated that AgNano affected metabolic rate and FU; however, it did not influence the development of hatchlings. This suggests that in ovo injection of AgNano reduces the need to use yolk fat as an energy source during embryonic development and consequently the remaining fat in the residual yolk sac may provide a potent source of nutritional reserves for chicks of few days after hatching.

Assessment of the accuracy of quantitative urine collection in mink (Mustela vison) using osmotic pumps for continuous release of p-amino-hippuric acid and inulin.

A method is described to assess the accuracy of quantitative collection of urine in small experimental animals using implanted Alzetr osmotic pumps for continuous release of specific urinary markers. The nominal pumping rate (10.00±0.15 µl/h; mean±SEM) of 10 osmotic pumps was verified (9.96±0.12 µl/h) in a l0-day in vitro assay in isotonic saline at 39.0 °C. Ten adult female mink (1100±34 g) had a 2-ml osmotic pump implanted intraperitoneally for 7 days while maintained in metabolic cages on a conventional mink diet. In 5 mink the pumps contained [3H]-labelled p-aminohippuric acid (PAH) only. The remaining 5 animals received a pump containing [H]-PAH and [14C]-labelled inulin. The experiment was well tolerated by all animals. In fed animals, the amount of urine collected per day was not influenced by the osmotic pumps, whereas 24 h of fasting (water allowed) caused a dramatic fall in urinary volume. In 4 consecutive 24-h collections of urine (n=l0 animals) the recovery of [3H]-PAH was 70.8±3.6% (range: 52.0-87.2%), and urinary plus faecal water (=total) recovery of [3H]-PAH averaged 77.0±3.7% (range: 60.3%-94.3%). For [14C]-inulin (n=5 animals) the urinary and total recoveries were 68.4±2.2% and 77.2±2.4%, respectively. In urine the 14C to 3H counts-ratio was almost identical to that of the infusion solution, indicating that metabolic decomposition of the markers was negligible. The results indicate that the daily recovery of suitable urinary markers, released by implanted osmotic pumps, provides a reproducible and valid measure of the accuracy achieved in quantitative collection of urine in mink and probably also in other animal species. Hence, this technique may be useful in future studies on animal nutrition and/or drug disposition.