Change of plasma insulin-like growth factor-1 (IGF-1) concentration with early growth in Japanese beef cattle

The aim of the present study was to examine the change in plasma insulin‐like growth factor‐1 (IGF‐1) concentration with early growth, changes of bodyweight (BW) and relative dairy gain (RDG) in the pre‐ (PRW) and postweaning periods (POW) in Japanese beef cattle, and relationships with metabolites. A total of 33 calves, 22 Japanese black, 6 Japanese shorthorn and 5 of their crossbreed were studied. Insulin‐like growth factor‐1 and metabolite (glucose, triacylglycerol, nonesterified fatty acid) levels in the plasma, from jugular vein blood taken every month, were measured along with BW. Insulin‐like growth factor‐1 in POW increased dramatically with increase of BW (P < 0.05), and the correlation was positive at 0.52 (P < 0.01). Glucose levels correlated significantly with BW, RDG and IGF‐1 (P < 0.01). Metabolic required calorie correlated positively with IGF‐1 (P < 0.01). Also, correlations of BW in POW, with BW and RDG in PRW were positive (P < 0.01). Growth in PRW would be influenced by maternal effects, while active self‐secretion of IGF‐1 in POW might contribute to POW growth. These factors suggested that to increase growth in PRW, maintaining enough maternal effect and IGF‐1 level in POW, was important for establishing better growth after weaning.     

Leukocytes from heifers at different ages express insulin and insulin-like growth factor-1 (IGF-1) receptors

The objectives of this study were to investigate if insulin receptors (IR) and insulin-like growth factor-1 receptors (IGF-1R) could be detected on bovine leukocytes using fluorescence antibodies and flowcytometry, and use this method to investigate whether the amount of receptors differed among heifers at different ages. Twenty Danish Holstein heifers in the following three age groups were included in the investigation: (1) heifers aged 25-45 days (n = 8), (2) heifers aged 185-205 days (n = 7), and (3) heifers aged 780-900 days (approximately one month prepartum; n = 5). Antibodies against human IR and IGF-1R were used for indirect immunofluorescence staining of cells, and were found to cross-react with the bovine receptors. IR were found on lymphocytes, monocytes, and neutrophils in all animals, while IGF-1R were found only on monocytes and neutrophils. The percentage of IR+ lymphocytes was almost doubled from stage 1 to 3 (34% versus 57%) and IR expression on lymphocytes and monocytes increased significantly (P<0.01) from 6.80 and 13.60 to 8.24 and 17.50 in heifers aged 185-205 days and heifers aged 780-900 days, respectively. No differences were observed for neutrophil IR or IGF-1R expression. In conclusion, surface IR and IGF-1R can be detected on bovine leukocytes by flowcytometry. Interestingly, the highest numbers of IR were found in heifers one month prepartum. The regulation of IR and IGF-1R expression on bovine leukocytes, and their role in host immunity, needs further investigation.     

Effects of antimicrobials and weaning on porcine serum insulin-like growth factor binding protein levels

The effects of subtherapeutic antimicrobial supplementation and weaning on serum levels of IGF-I and insulin-like growth factor binding proteins (IGFBP)-2, -3 and -4 were determined in crossbred weanling pigs. At weaning, pigs were allotted to a diet containing 21.8% crude protein and 1.15% lysine with or without Aureozol (110 mg/kg of Aureomycin chlortetracycline, 110 mg/kg of sulfathiazole, and 55 mg/kg of penicillin) for 4 wk. Insulin-like growth factor-binding proteins and IGF-I analyses were performed on blood samples that were drawn weekly. Weaning decreased serum IGFBP-3 levels in both control and Aureozol-treated groups on d 6 and d 14 (P < 0.05) relative to preweaning levels. The IGFBP-3 values returned to preweaning levels by d 21. Although the circulating levels of both the 43-kDa and the 39-kDa glycosylation variants of IGFBP-3 were affected by weaning, the level of the 39-kDa IGFBP-3 was affected relatively more than that of the 43-kDa IGFBP-3 (P < 0.05). Compared with circulating IGFBP-3 levels in control pigs, Aureozol-treated pigs had higher circulating IGFBP-3 levels on d 21 (43%, P < 0.05) and d 27 (46%, P < 0.05). In direct contrast to the effect of weaning on serum IGFBP-3 level, serum IGFBP-2 levels increased on d 6 and d 14 after weaning (P < 0.05) and decreased to preweaning levels by d 21. The IGFBP-2 levels continued to decline and were less than preweaning levels by d 27 (P < 0.05). Aureozol treatment had no effect on serum IGFBP-2 levels at any time. Serum levels of nonglycosylated IGFBP-4 were not affected by either weaning or Aureozol supplementation. Weaning decreased circulating IGF-I concentration on d 6 in both control and Aureozol-treated pigs (76 and 73%, respectively, P < 0.05) and on d 14 (62%, P < 0.05) and d 21 (32%, P < 0.05) in control pigs. Aureozol-supplemented pigs had higher serum IGF-I concentrations than control pigs on d 14 (82%, P < 0.05), d 21 (55%, P < 0.05), and d 27 (36%, P < 0.05). The Aureozol-fed pigs had a 14.2% increase in BW gain (P < 0.05) and a 59.6% increase in ADG (P < 0.05) compared with pigs fed the control diet. Both Aureozol-supplementation and weaning cause changes in serum IGFBP levels and IGF-I concentrations that might be involved in regulating rate and efficiency of growth.     

Determination of circulating levels of insulin-like growth factor II (IGF-II) in swine

A heterologous radioimmunoassay system was developed for the determination of circulating IGF-II concentrations in swine. The assay utilized a monoclonal antibody against human IGF-II (Amano Intl. Ez, VA) and bovine IGF-II (Monsanto Co., MO) as the cold standard and iodinated ligand. Serial dilutions of acid-ethanol extracted normal swine sera resulted in a curve which was parallel to the bovine IGF-II standard curve. Recovery of unlabeled standard added to extracted swine sera was 101%. Neither IGF-I nor insulin were capable of cross-reacting in this assay at levels up to 100-fold excess.

Using this assay, serum IGF-II levels were determined to be significantly lower when subnormal growth hormone (GH) levels existed such as in hypophysectomized swine. However, in contrast to serum IGF-I concentrations, supranormal levels of porcine GH (pGH) did not elevate serum IGF-II concentrations after 13 wk of treatment in 25 kg hogs (initial body wt). In addition, serum IGF-II levels were reduced in fasted swine, despite a significant increase in circulating GH concentrations. Thus, although normal concentrations of GH are required for maintenance of physiological levels of IGF-II in swine, the mechanism for stimulation of IGF-II secretion is less GH-dependent than IGF-I.     

Polymorphism and expression of insulin-like growth factor 1 (IGF1) gene and its association with growth traits in chicken

1. The objectives of the study were to detect polymorphism in the coding region of the IGF1 gene, explore the expression profile and estimate association with growth traits in indigenous and exotic chickens.

2. A total of 12 haplotypes were found in Cornish, control layer and Aseel breeds of chicken in which the h1 haplotype was most frequent.

3. Nucleotide substitutions among haplotypes were found at 21 positions in the IGF1 gene in which 4 substitutions resulted in non-synonymous mutations in the receptor binding domain of the IGF1 protein.

4. The haplogroup showed a significant effect on body weight at 24 and 42 d of age in the control layer line, body weight at 42 d and daily weight gain between 29 and 42 d in the control broiler line, daily weight gain between 29 and 42 d in Cornish, and body weights at 42 d as well as daily weight gain between 29 and 42 d in Aseel birds.

5. IGF1 expression varied among the breeds during embryonic and post-hatch periods. The expression among the haplogroups varied in different chicken tissues. The effect of haplogroup on myofibre number in pectoral muscle was non-significant, although there was significant variation in numbers between d 1 and d 42, and between broiler and layer lines.

6. It was concluded that the coding region of the IGF1 gene was polymorphic, expressed differentially during the pre-hatch and post-hatch periods, and haplogroups showed significant association with growth traits in chicken.     

Genetic correlation between serum insulin-like growth factor-1 concentration and performance and meat quality traits in Duroc pigs

This study was intended to examine whether serum IGF-I concentration is appropriate for use as a physiological predictor for genetic improvement of meat production and meat quality traits in pigs. Heritabilities and genetic correlations were estimated for these traits. The Duroc breed used in this study was selected for seven generations for average daily BW gain (DG) from 30 to 105 kg of BW, loin-eye muscle area (EM), backfat thickness (BF), and intramuscular fat (IMF) content. Serum IGF-I concentration of boars and gilts at the fourth generation of selection and that of boars, gilts, and barrows from the fifth to seventh generations of selection were measured at 8 wk (IGFI-8W) for 832 animals and again at the time they reached 105 kg of BW (IGFI-105KG) for 834 animals. A multivariate REML procedure was used to estimate genetic parameters with a model incorporating generation of selection, sex, common environmental effect of litter, and individual additive genetic effects. Heritability estimates for IGFI-8W and IGFI-105KG were 0.23 +/- 0.02 and 0.26 +/- 0.03, respectively. The estimates of common environmental effect for IGFI-8W and IGFI-105KG were 0.20 +/- 0.02 and 0.03 +/- 0.01, respectively. Positive genetic correlations were estimated between IGFI-8W and DG (0.26 +/- 0.08), EM (0.22 +/- 0.10), and IMF (0.32 +/- 0.10). Moreover, the positive genetic correlation between IGFI-105KG and EM was 0.42 +/- 0.08. These results indicate that serum IGF-I concentration at an early stage of growth was effective for prediction of IMF, but it was not a reliable physiological predictor of genetic merit of meat production traits.     

摘除卵巢对布尔山羊杂种母羊组织IGF-I和IGF-1R基因表达的影响

为了研究卵巢摘除对布尔山羊杂种母羊类胰岛素样生长因子1(ginsulin-like growth factor 1,IGF-1)和类胰岛素样生长因子1受体(ginsulin-like growth factor 1receptor,IGF-1R)基因表达的影响。本试验将体质量相近的5月龄布尔山羊杂种母羊作为研究对象,随机分为处理组和对照组,每组20只。试验开始时摘除处理组母羊的卵巢,对照组不摘除。饲养50d后,利用实时荧光定量PCR(qRT-PCR)相对定量方法检测肝脏、背最长肌、股二头肌和肾周脂肪中IGF-1和IGF-1R基因mRNA的相对表达量。卵巢摘除后母羊背最长肌和肝脏组织中IGF-1基因mRNA的相对表达量分别是对照组的6.19倍和6.01倍(P<0.01);IGF-1R基因表达量分别是对照组的11.86倍和9.96倍(P<0.01)。处理组母羊股二头肌中IGF-1基因mRNA的相对表达量与对照组差异不显著(P>0.05);IGF-1R基因是对照组的4.86倍,且差异显著(P<0.05)。在肾周脂肪组织中,处理组母羊IGF-1基因和IGF-1R基因mRNA的相对表达量较对照组增加,但差异均不显著(P>0.05)。由此可见,卵巢摘除可以上调背最长肌和肝脏中IGF-I和IGF-IR基因的表达以及股二头肌中IGF-IR基因的表达。     

纳米银对断奶仔猪生长性能、肠道绒毛形态及微生物菌群的影响

文章旨在研究日粮添加不同水平的纳米银对断奶仔猪生长性能、肠道形态及微生物菌群的影响。本研究共进行3个试验,试验1收集8头断奶后7 d仔猪的回肠内容物,在体外37℃条件下分别添加0、20、40和80μg/kg纳米银,孵育4 h。结果显示,随着纳米银添加水平的升高,回肠内容物大肠杆菌和乳酸杆菌的含量显著线性降低(P<0.05),但对乳酸杆菌比例无显著影响(P>0.05)。试验2分为3个组,每组10头21 d断奶的仔猪,日粮中分别添加0、20和40 mg/kg纳米银,结果发现随着纳米银添加水平的升高,断奶后2周仔猪的日增重表现为显著线性升高(P<0.05),同时回肠大肠杆菌含量有显著线性降低的趋势(P=0.07),显著降低了细菌总量和奇异菌属含量(P<0.05)。20 mg/kg纳米银组产气荚膜杆菌与梭菌比例最低(P<0.05)。试验3分为3组,每组选择10头21 d断奶仔猪,日粮中分别添加0、20和40 mg/kg纳米银,结果发现,日粮纳米银添加水平对仔猪断奶后前两周绒毛形态无显著影响(P>0.05),而隐窝深度有降低趋势(P=0.08)。20 mg/kg纳米银组仔猪在断奶前两周表现为最高(P<0.05),之后随着纳米银添加水平的升高在3~4周显著降低(P<0.05),料比显著升高(P<0.05)。日粮添加低剂量的纳米银可以改善断奶仔猪的采食量和日增重,适宜添加水平为20~40 mg/kg。     

Effects of flax supplementation and a combined trenbolone acetate and estradiol implant on circulating insulin-like growth factor-I and muscle insulin-like growth factor-I messenger RNA levels in beef cattle

We evaluated effects of a 5% (dry matter basis) ground flaxseed supplement (flax) and a trenbolone acetate and estradiol-17beta implant, Revalor-S, on circulating IGF-I and muscle IGF-I messenger RNA (mRNA). Sixteen crossbred yearling steers (initial BW = 397 kg) were assigned randomly to one of four treatments: 1) flax/implant; 2) nonflax/implant; 3) flax/nonimplant; and 4) nonflax/nonimplant. Serum was harvested from blood collected on d 0 (before implant or flax addition), 14, and 28, and used in subsequent analyses of circulating IGF-I. Biopsy samples (0.5 g) were obtained from the longissimus muscle on d 0, 14, and 28. Total RNA was isolated from the muscle samples, and real-time quantitative-PCR was used to assess relative differences in IGF-I mRNA. Flax supplementation had no effect (P > 0.10) on circulating IGF-I concentrations. Following implantation, sera from implanted steers had 52 and 84% greater (P < 0.05) IGF-I concentrations than sera from nonimplanted steers on d 14 and 28, respectively. On d 28, local muscle IGF-I mRNA levels increased 2.4-fold (P < 0.01) in biopsy samples obtained from implanted compared with nonimplanted steers. Muscle biopsy samples from nonflax cattle had 4.4-fold higher (P < 0.01) levels of IGF-I mRNA than those from flax cattle on d 28. To determine whether a component of flax, alpha-linolenic acid (alphaLA), was directly responsible for IGF-I mRNA down-regulation, we incubated primary cultures of bovine satellite cells, from implanted and nonimplanted steers, in two concentrations of alphaLA (10 nM and 1 microM). An implant x dose interaction (P < 0.05) was observed for IGF-I mRNA concentrations in bovine satellite cells cultured for 72 h with alphaLA. Satellite cells from nonimplanted steers had similar (P > 0.10) IGF-I mRNA concentration regardless of the level of alphaLA exposure; however, satellite cells from implanted steers exposed to 10 nM and 1 microM alphaLA had 2.5- and 2.0-fold greater IGF-I mRNA levels, respectively, than cells from implanted steers that were not exposed to alphaLA (P < 0.05). Administration of a Revalor-S implant increased circulating IGF-I and local muscle IGF-I mRNA concentrations in finishing cattle. However, muscle IGF-I mRNA levels were decreased by flax supplementation. Muscle cell culture experiments suggested that alphaLA was not responsible for the IGF-I mRNA down-regulation.     

Determination of insulin-like growth factor 1 (IGF1) and IGF binding protein levels in swine

A heterologous radioimmunoassay system was validated for the determination of IGF1 concentrations in swine sera. Parallelism, accuracy and response to physiological stimuli were obtained following the incubation of serum samples with 1M glycine-glycine HC1 buffer at a pH of 3.5 +/- 0.2 for 24 hours at 37C. Following acidification and neutralization, circulating IGF1 concentrations were significantly (P less than .05) reduced in hypophysectomized swine and elevated in swine injected with porcine growth hormone (pGH) when compared to IGF1 levels in control hogs. IGF binding protein levels were also increased following GH administration and reduced by hypophysectomy. In addition, circulating IGF1 concentrations were significantly (P less than .05) correlated with body size in three types of swine which differ in growth rate and mature body weight. These data suggest that IGF1 is involved in the regulation of swine growth in vivo and that its physiologic regulation is similar to that in humans.     

还原型谷胱甘肽对肉鸡生长及血清IGF-1水平、组织IGF-1 mRNA表达的影响

9日龄黄羽雌性肉鸡1 000只随机分为A、B、C、D 4个组,每组设5个重复,每个重复50只。在A、B、C、D组的日粮中分别添加剂量为0、80、120、160mg/kg的还原型谷胱甘肽(GSH),饲养期84 d。观察GSH对肉鸡生长性能、血清类胰岛素生长因子1(IGF-1)、T3、T4水平以及组织IGF-1 mRNA表达的影响。结果表明,(1)添加GSH的鸡只血中GSH水平显著高于对照组(A组);(2)添加GSH的鸡只平均体质量和平均日增重均高于A组,其中B组显著高于A组;(3)添加GSH的鸡只血中IGF-1水平显著高于A组,血中T3水平明显升高,T4水平有升高趋势;(4)各试验组肝脏IGF-1 mRNA的表达水平有所增高,但不明显。35d时,C组胸肌组织的IGF-1 mRNA表达水平显著性高于A组。结果提示,肉鸡饲粮中添加GSH可增强肝脏IGF-1的分泌和肌肉组织IGF-1 mRNA的表达,血中IGF-1水平升高,而促进鸡只生长。     

Effects of dietary protein and growth hormone-releasing peptide (GHRP-2) on plasma IGF-1 and IGFBPs in Holstein steers

This study was conduct to determine the influence of dietary protein on the response of plasma insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding proteins (IGFBPs) to exogenous growth hormone releasing peptide-2 (GHRP-2 or KP 102) in Holstein steers. Eight 16-month-old Holstein steers were grouped by liveweight to two feeding treatments; high protein (HP; CP 1.38 kg/day and TDN 4.5 kg/day DM intake, n=4) or low protein (LP; CP 0.66 kg/day and TDN 4.42 kg/day DM intake, n=4). The experiment was a single reverse design whereby each group was injected twice daily with GHRP-2 (12.5 microg/kg body weight (BW)/day) or saline solution into the jugular vein for a 6-day period. Plasma IGF-1 in the HP group were higher than in the LP group (P<0.05), but plasma 34 kDa IGFBP-2 was lower in the HP than the LP group (P<0.05). The amplitude of the maximum growth hormone (GH) peaks responding to GHRP-2 injection were higher at day 1 than at day 6 of saline or GHRP-2 treatment in both LP and HP steers (P<0.05). The area under the GH response curve for 180 min after the GHRP-2 injection was not significantly different between the LP and the HP groups at days 1 and 6. A response in plasma IGF-1 concentration to GHRP-2 treatment in the HP group was observed at day 1 (198.9+/-18.1 ng/ml), day 2 (195.2+/-21.1 ng/ml) and day 6 (201.3+/-14.8 ng/ml) (P<0.05). No increase in plasma IGF-1 was observed from GHRP-2 administration in the LP group. Although the response of plasma IGF-1 concentration to GHRP-2 administration was increased in the HP group (P<0.05), there was no apparent effect of GHRP-2 treatment on plasma 38-43 kDa IGFBP-3 and 34 kDa IGFBP-2 at days 2 and 6 of treatment. In conclusion, it is proposed that the 34 kDa IGFBP-2 is sensitive to dietary protein level and may play an important role in the regulation of circulating IGF-1 in ruminant. In addition, increased plasma IGF-1 concentration observed in the HP group in response to the GHRP-2 treatment did not appear to affect plasma IGFBPs.     

Developmental patterns of plasma insulin-like growth factor-1 concentrations in sheep

A study was undertaken to examine the ontogeny of circulating insulin-like growth factor-1 (IGF-1) concentrations in sheep. The trial was a balanced 2×2 factorial design incorporating the effects of sex and rearing rank with a total of 48 animals. Blood sampling was initiated four weeks post-weaning (about 3 months of age) and continued every 2 weeks for 6 months and then every 4 weeks for 7 months. Fecal egg counts and plasma concentrations of non-esterified fatty acids (NEFA) were also determined. IGF-1 concentration was positively related to live weight throughout the trial, even when adjusted to common sex and rearing rank. Sex of lamb had a significant effect on plasma IGF-1 concentrations with concentrations in males being greater than those in females. Puberty in females, as determined by date of first estrus, was associated with an increase in plasma IGF-1 concentrations. Although puberty in males was not measured, a surge in plasma IGF-1 concentrations around the approximate time of puberty in males resulted in a marked divergence between the sexes which remained throughout the study. Rearing rank did not influence plasma IGF-1 concentrations beyond 7 months of age.

Plasma IGF-1 concentrations tended to be negatively associated with plasma NEFA concentrations and fecal egg counts but relationships were only occasionally significant.

IGF-1 levels were highly repeatable, concentrations at the first sample being significantly correlated with those at all subsequent samples. Implications of these results in relation to potential use of plasma IGF-1 concentration as a genetic marker for productivity are discussed.     

Effects of immune challenge on concentrations of serum insulin-like growth factor-I and growth performance in pigs

This study was designed to determine the long-term effects of repeated endotoxin treatment or immunization against human serum albumin on concentrations of serum insulin-like growth factor-I (IGF-I) and other indicators of growth performance in growing pigs. Thirty gilts (38.5 +/- 0.9 kg) were randomly assigned to 5 treatment groups (n = 6 animals/group): 1) lipopolysaccharide injections, 2) lipopolysaccharide pair-fed, 3) human serum albumin immunization, 4) human serum albumin pair-fed, and 5) control. Pigs in the lipopolysaccharide group were treated intramuscularly with lipopolysaccharide on Days 0-3. The pigs in the human serum albumin group were immunized with human serum albumin emulsified in Freund's adjuvant on Day 0 and administered a booster on Day 28. The lipopolysaccharide pair-fed pigs were matched by body weight and pair-wise fed with pigs treated with lipopolysaccharide. Similarly, human serum albumin pair-fed pigs were matched to human serum albumin immunized pigs. Serum IGF-I concentrations did not differ between or within groups. There was no difference in feed disappearance between groups prior to the initiation of treatments. The lipopolysaccharide group had a decrease (P = 0.013) in feed disappearance on Day 0 compared with control and human serum albumin groups. On Day 1, both lipopolysaccharide and human serum albumin groups differed (P < 0.05) from control. Average daily gain and total weight gain did not differ between groups; however, feed efficiency differed (P < 0.05) between lipopolysaccharide and control groups. Long-term effects of repeated endotoxin challenge or immunization on IGF-I concentrations and growth were not evident in the present study. This failure presumably was due to the development of endotoxin tolerance and a relatively innocuous vaccination against human serum albumin.     

Effects of feeding Salmonella enterica serovar Typhimurium or serovar Choleraesuis on growth performance and circulating insulin-like growth factor-I, tumor necrosis factor-alpha, and interleukin-1beta in weaned pigs

The most common Salmonella serovars causing clinical disease in pigs are Salmonella enterica serovars Typhimurium (Typhimurium) and Choleraesuis. Given that the swine host-adapted serovar Choleraesuis has been reported to cause systemic disease, a different disease outcome from that of Typhimurium, our working hypothesis was that this serovar would likely engage systemic immune-inflammatory mechanisms, resulting in elevated systemic cytokine secretion. Forty-eight weaned pigs were blocked by BW and sex, and randomly allotted to 1 of 3 treatments in a 14-d study. Each treatment had 8 replicates (pens), with 2 pigs/pen. The treatments consisted of a negative control and pigs repeatedly fed 10(8) cfu of Typhimurium or Choleraesuis. On d 0, the pigs were fed Choleraesuis or Typhimurium in dough balls, and the bacteria were refed twice weekly throughout the experiment. Control pigs received dough balls without bacteria. All pigs were housed in temperature-controlled rooms under constant lighting and were fed a standard corn-soybean meal-based nursery diet. Pig BW and feed disappearance were used to determine ADG, ADFI, and G:F. Rectal temperatures were obtained daily from 1 pig/pen beginning 2 d before the first bacterial feeding through d 7 using rapid-response digital thermometers. Serum was collected on d 0, 7, and 14 from a single pig/pen for analysis of IGF-I, tumor necrosis factor-alpha , and IL-1beta. There was no change in the rectal temperature of the control or the Typhimurium-challenged pigs (compared with d 0) or when comparing Typhimurium-challenged pigs with control animals. In contrast, pigs fed Choleraesuis had increased rectal temperatures beginning on d 2 and continuing through d 7 (P < 0.05), with the greatest elevation on d 3 (P < 0.001) compared with the control pigs. Average daily gain and ADFI of pigs challenged with Typhimurium did not differ from those of the control animals. Pigs fed Choleraesuis had a 25% reduction in ADG (P < 0.0001) and ADFI (P < 0.002) compared with the control pigs. On d 7, pigs fed Choleraesuis had reduced serum IGF-I compared with control (P < 0.01) or Typhimurium-challenged pigs (P = 0.01). Bacterial feeding did not affect serum tumor necrosis factor-alpha or IL-1beta compared with control pigs at any time throughout the experiment. We conclude that repeated exposure of weaned pigs to Choleraesuis reduced growth performance in the absence of changes in systemic inflammatory cytokines.