J.W. Schrama

Soybean meal induces intestinal inflammation in common carp (Cyprinus carpio L.).

The development of soybean meal (SBM) induced enteritis in the hindgut of the omnivorous common carp (Cyprinus carpio L.). The developed condition was assessed when carp, continuously fed on animal protein, were transferred to a diet in which 20% of the protein was replaced by SBM. After week 1, most of the inflammation parameters were already present, but at week 3, a strong aggravation of the condition was observed which included a shortening of the mucosal folds, the disappearance of the supranuclear vacuoles, an increased number of goblet cells, a thickened lamina propria and sub-epithelial mucosa with increased numbers of basophilic granulocytes as well as a decreased uptake capacity of enterocytes (impaired endocytosis and microvilli). Contrary to previous observations made with respect to Atlantic salmon, common carp start to recover from the fourth to the fifth week after switching to SBM feeding. At this stage, the supranuclear vacuoles refill and most of the parameters revert to basal levels. During the enteritis process, a real-time quantitative PCR analysis was conducted to measure the expression of inflammatory and anti-inflammatory cytokine genes in the isolated intraepithelial lymphocytes (IEL). The pro-inflammatory interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha1 (TNF-alpha1) genes were up-regulated during the inflammation process while the anti-inflammatory interleukin 10 (IL-10) was down-regulated after an initial up-regulation at week 1. Transforming growth factor beta (TGF-beta) expression showed an up-regulation from week 3 onwards despite the high Ct value and the low primer efficiency shown. This study confirms the contribution of IEL (mainly T-like cells) and basophils in the enteritis process. In addition, the results show a clear involvement of up- and down-regulated cytokine genes in both the onset and recovery of the SBM-induced enteritis in the hindgut of carp.

Fermented co-products and fermented compound diets for pigs: a review

This review deals with the properties of fermented diets and their effects on growth performance and gastrointestinal environment of pigs. In addition, some possible modes of action are hypothesized. Starch and sugar rich liquid co-products have a high potential for fermenting during storage. Soaking compound feed with water is another means of achieving a fermented diet. These diets are characterized by a pH between 3.5 and 4.5, high levels of lactic acid, and, to a lesser extent, acetic acid and alcohol. Fermented diets seem to improve growth performance of pigs, compared with non-fermented diets. The exact reasons for this are not yet clear; however, some hypotheses are given. Based on a limited number of studies, fermented diets reduce the gastric pH and the number of Coliform bacteria in the gastrointestinal tract compared with non-fermented diets. Furthermore, there are some indications that fermented diets may positively affect pancreatic secretion, villus architecture, digestibility and absorption of dietary nutrients. Fermented diets may reduce the physical activity of pigs. More specific studies on the effect and modes of action of fermented diets are needed to allow firmer conclusions to be drawn. # 1999 Elsevier Science B.V. All rights reserved.

Divergent Antibody Responses to Vaccines and Divergent Body Weights of Chicken Lines Selected for High and Low Humoral Responsiveness to Sheep Red Blood Cells

Primary and secondary antibody responses to intramuscularly administered proteins of Eschericia coli (F11), Newcastle disease virus (NCD), infectious bronchitis virus (IB), and infectious bursal disease virus (IBD), respectively, were measured at weekly intervals in two chicken lines. The latter had been divergently selected for high and low antibody responses to sheep red blood cells (SRBC), and in a random-bred control line. An oil-based adjuvant was required to induce primary and secondary antibody responses to NCD, IB, and IBD. With respect to F11, elevated antibody responses were found in birds sensitized and boosted to F11 with and without adjuvant. The humoral response to F11 and to all viral antigens was significantly higher in the high (H) line than in the low (L) line, whereas the control (C) line showed intermediate titers. At 5 and 17 weeks of age, L line birds were significantly heavier than birds of the H and the C lines. A negative phenotypic correlation within lines between body weight at 17 weeks of age and antibody titers at 1 week after sensitization was found, but no further correlations between humoral responses and body weight or growth could be established. The present results suggest that selection for enhanced humoral responsiveness to SRBC resulted in enhanced responsiveness to components of several vaccines. Mechanisms underlying the relationship between divergent selection for immune responsiveness and body weight are discussed.

Can we predict behaviour in pigs?: Searching for consistency in behaviour over time and across situations

Individual differences in animal behaviour could elucidate the differences in stress coping style, which have consequences for production, health and welfare. Therefore, individual behavioural differences in pigs and consistency of responses in different test situations were studied. If differences in behaviour reflect coping characteristics, then behaviour in one situation should predict behavioural reactions in other situations and at other times. In this study, a backtest was performed on 315 Great Yorkshire∗ Dutch Landrace piglets at 3, 10 and 17 days of age. On day 3, groups of approximately 10 piglets per sow were formed, based on escape behaviour in the first backtest (backtest score): high resisting (HR, all scores >3), low resisting (LR, all scores <3), miscellaneous (MISC, various scores between 0 and 10) or original (OR) litters to determine if group composition would influence coping behaviour. In weeks 5–7 and/or 10–12, a human approach test (HAT), a novel object test (NOT), and an open door test (ODT) were performed with all pigs simultaneously, in the home pen. Pearson correlation coefficients were calculated between the test results and a factor analysis was performed. Furthermore, data were analysed on pen level, and within MISC- and OR-pens on animal level, using multivariate linear models. Significant correlations were found between the backtests and between HAT, NOT and ODT. Backtest results on three ages loaded on the same factor, and HAT, NOT and ODT at one age also loaded on one factor. No differences were found in HAT, NOT and ODT for the different pens (HR, LR, MISC and OR). On animal level, animals with higher backtest scores also had higher HAT scores at 5–7 weeks (P<0.05) within the MISC-pens. At 10–12 weeks, no differences were found. This study suggests that there are consistencies in behaviour of pigs over time and across situations, so coping can be regarded as a trait variable. However, since correlations are well below one, we suggest that other factors such as time (development) and (test) situation may also play an important role in determining an individual’s behavioural reaction. The absence of correlations between backtest and the group tests is explained by the theory that these different tests measure different aspects of the coping style.

Time‐related changes of the intestinal morphology of Atlantic salmon, Salmo salar L., at two different soybean meal inclusion levels

Abstract Soybean meal (SBM) induces enteritis in the distal intestine of Atlantic salmon. The present study assesses the effects of SBM concentrations on the kinetics of the enteritis process. Fish of 300 g, kept at 12 degrees C, were fed diets with different SBM inclusions: 0%, 10% and 20% SBM for 57 days. Samples of the distal intestine of five fish per treatment were taken for histological and electron microscopical analysis. A semi-quantitative scoring system was used to assess the degree of the morphological changes induced by SBM feeding in the distal intestinal epithelium. The first signs of enteritis appeared earlier in the salmon fed the 20SBM diet than in those fed the 10SBM diet. Thereafter, the condition increased steadily, displaying no signs of recovery. Furthermore, at the lower concentration, the process marking the onset of enteritis began more gradually than at the higher concentration and it displayed a tendency to stabilize after 13-20 days of continuous feeding. Electron microscopy indicated that the endocytosis process was hampered at day 3 of 20SBM and at 7 days of 10SBM. Furthermore, a strong reduction of microvilli was already evident after 7 days of 20SBM feeding, thus indicating a decreased uptake capacity of the distal enterocytes. In addition, transformation and migration of eosinophilic granulocytes was observed, which, in combination with the lysozyme C immunoreactivity supports their protective role during the inflammatory process in the distal gut of Atlantic salmon. It can be concluded that the severity of enteritis and its kinetics are concentration-dependent, showing no signs of recovery during feeding with diets containing SBM.

Early in vivo cytokine genes expression in chickens after challenge with Salmonella typhimurium lipopolysaccharide and modulation by dietary n−3 polyunsaturated fatty acids

We studied the effects of Salmonella typhimurium lipopolysaccharide (LPS) on in vivo cytokine mRNA levels in chickens, and investigated whether these levels could be altered by different nutrients. Two hundred and forty chicks were assigned in a 2 x 4 factorial design of treatments. Factors were intravenous injection with S. typhimurium LPS, or saline (control), and four dietary fat sources: corn oil (CO), linseed oil (LO), menhaden oil and beef tallow (BT). Two hours after injection birds were killed and their spleens removed for RNA extraction. Quantitative real-time RT-PCR assays for mRNA of chicken IFN-gamma, IL-6, IL-8, IL-15, IL-18 and 28S rRNA were used to obtain the in vivo splenic cytokine profiles. Expression levels of IL-6, IL-8, IL-18 and IFN-gamma mRNA increased, but IL-15 mRNA decreased 2h after challenge with LPS compared with saline controls. In saline-injected control chickens, the dietary oil source did not affect the splenic mRNA level of any cytokine. In LPS challenged chickens IFN-gamma mRNA was significantly higher in the chickens fed the fish oil enriched diet compared with the LO, CO and BT enriched diets. The present data imply that avian IL-15 has, at least partially, a different function compared to its mammalian counterpart, and in addition, chicken innate immune responses might be affected differently by n-3 PUFA compared to mammals.

Influence of electrolyte balance and acidifying calcium salts in the diet of growing-finishing pigs on urinary pH, slurry pH and ammonia volatilisation from slurry

This study investigated the effects of dietary electrolyte balance (dEB=Na+K-Cl meq/kg DM) and acidifying Ca-salts on slurry pH and ammonia emission from slurry of growing-finishing pigs. Ninety gilts of about 40 kg BW were randomly allotted to 18 diets in five replicates. Two basal diets were used. Diet A had a high dEB (320 meq/kg DM) and diet B a low dEB (100 meq/kg DM). Each diet was supplemented with one of the four Ca-salts (CaCO3, CaSO4, Ca-benzoate or CaCl2) to increase Ca content by 3 or 6 g per kg of diet. Faeces and urine were collected separately in metabolism cages and mixed as slurry. In a subsample of this slurry, pH and ammonia emissions were measured in a laboratory system. The low dEB diet produced urine and slurry with lower pH, and less ammonia was emitted from the slurry. Replacing dietary CaCO3 by CaCl2, CaSO4 and Ca-benzoate reduced ammonia emission by 30, 33 and 54%, respectively. It is concluded that ammonia emission can be reduced by decreasing dEB level and adding CaSO4 and CaCl2 to the diet instead of CaCO3. The most profound effect is achieved when CaCO3 is replaced by Ca-benzoate.

Link between lipid metabolism and voluntary food intake in rainbow trout fed coconut oil rich in medium-chain TAG.

We examined the long-term effect of feeding coconut oil (CO; rich in lauric acid, C12) on voluntary food intake and nutrient utilisation in rainbow trout (Oncorhynchus mykiss), with particular attention to the metabolic use (storage or oxidation) of ingested medium-chain TAG. Trout were fed for 15 weeks one of the four isoproteic diets containing fish oil (FO) or CO as fat source (FS), incorporated at 5% (low fat, LF) or 15% (high fat, HF). Fat level or FS did not modify food intake (g/kg(0·8) per d), despite higher intestinal cholecystokinin-T mRNA in trout fed the HF-FO diet. The HF diets relative to the LF ones induced higher growth and adiposity, whereas the replacements of FO by CO resulted in similar growth and adiposity. This, together with the substantial retention of C12 (57% of intake), suggests the relatively low oxidation of ingested C12. The down-regulation of carnitine palmitoyl-transferase-1 (CPT-1) confirms the minor dependency of medium-chain fatty acids (MCFA) on CPT-1 to enter the mitochondria. However, MCFA did not up-regulate mitochondrial oxidation evaluated using hepatic hydroxyacyl-CoA dehydrogenase as a marker, in line with their high retention in body lipids. At a low lipid level, MCFA increased mRNA levels of fatty acid synthase, elongase and stearoyl-CoA desaturase in liver, showing the hepatic activation of fatty acid synthesis pathways by MCFA, reflected by increased 16 : 0, 18 : 0, 16 : 1, 18 : 1 body levels. The high capacity of trout to incorporate and transform C12, rather than to readily oxidise C12, contrasts with data in mammals and may explain the absence of a satiating effect of CO in rainbow trout.

Macronutrient-induced differences in food intake relate with hepatic oxidative metabolism and hypothalamic regulatory neuropeptides in rainbow trout (Oncorhynchus mykiss).

This study examines how dietary macronutrient-induced changes in voluntary food intake (FI) relate to changes in markers of hepatic oxidative metabolism and in the expression of FI regulatory neuropeptides in a teleost model, the rainbow trout. Rainbow trout were fed for 6weeks with one of four iso-energetic diets (2×2 factorial design), containing either a high (HP, ~500 g·kg(-1) DM) or a low (LP, ~250 g·kg(-1) DM) protein level (PL) with, at each PL, fat (diets HP-F and LP-F) being substituted by an iso-energetic amount of gelatinized corn starch (diets HP-St and LP-St) as non-protein energy source (ES). Irrespective of the dietary PL, FI (g·kg(-0.8)·d(-1)) and digestible energy intake (DEI, kJ·kg(-0.8)·d(-1)) were significantly (P<0.05) reduced by the iso-energetic replacement of fat by starch as non-protein ES. Interestingly, trout fed these St-diets had higher gene expression of markers of hepatic oxidative phosphorylation (OxPhos), i.e., ubiquinol-cytochrome c reductase subunit 2 (UCR2) and cytochrome oxidase subunit 4 (COX4) and of aerobic oxidative capacity (CS, citrate synthase), which paralleled glucokinase (GK) transcription. This positive relation suggests that glucose phosphorylation and markers of mitochondrial OxPhos are linked at the hepatic level and possibly triggered the observed reduction in FI. Moreover, trout displaying the reduced FI had higher cocaine amphetamine regulator transcript (CART) mRNA in hypothalamus, whereas neuropeptide Y (NPY) mRNA did not follow the macronutrient-induced changes in FI. Further studies are needed to unravel the mechanisms by which diet-induced changes in hepatic metabolism inform central feeding centers involved in the regulation of FI in fish.

Constraints on Energy Intake in Fish: The Link between Diet Composition, Energy Metabolism, and Energy Intake in Rainbow Trout

The hypothesis was tested that fish fed to satiation with iso-energetic diets differing in macronutrient composition will have different digestible energy intakes (DEI) but similar total heat production. Four iso-energetic diets (2×2 factorial design) were formulated having a contrast in i) the ratio of protein to energy (P/E): high (HP/E) vs. low (LP/E) and ii) the type of non-protein energy (NPE) source: fat vs. carbohydrate which were iso-energetically exchanged. Triplicate groups (35 fish/tank) of rainbow trout were hand-fed each diet twice daily to satiation for 6 weeks under non-limiting water oxygen conditions. Feed intake (FI), DEI (kJ kg−0.8 d−1) and growth (g kg−0.8 d−1) of trout were affected by the interaction between P/E ratio and NPE source of the diet (P<0.05). Regardless of dietary P/E ratio, the inclusion of carbohydrate compared to fat as main NPE source reduced DEI and growth of trout by ∼20%. The diet-induced differences in FI and DEI show that trout did not compensate for the dietary differences in digestible energy or digestible protein contents. Further, changes in body fat store and plasma glucose did not seem to exert a homeostatic feedback control on DEI. Independent of the diet composition, heat production of trout did not differ (P>0.05). Our data suggest that the control of DEI in trout might be a function of heat production, which in turn might reflect a physiological limit related with oxidative metabolism.