Reducing the CP content and increasing the fermentable carbohydrates (FC) content of the diet may counteract the negative effects of protein fermentation in newly weaned piglets fed high-CP diets. To study the synergistic effects of CP and FC on gut health and its consequences for growth performance, 272 newly weaned piglets (26 d of age, 8.7 kg of BW) were allotted to 1 of 4 dietary treatments in a 2 x 2 factorial arrangement, with low and high CP and low and high FC content as the factors. Eight piglets from each dietary treatment were killed on d 7 postweaning. Feces and digesta from ileum and colon were collected to determine nutrient digestibility, fermentation products, and microbial counts. In addition, jejunum tissues samples were collected for intestinal morphology and enzyme activity determination. During the entire 4-wk period, interactions between the dietary CP and FC contents were found for ADFI (P = 0.022), ADG (P = 0.001), and G:F (P = 0.033). The high-FC content reduced ADFI, ADG, and G:F in the low-CP diet, whereas the FC content did not affect growth performance in the high-CP diet. Lowering the CP content of the low-FC diet improved ADFI and ADG, whereas lowering the CP content of the high-FC diet did not influence growth performance. The low-CP diets resulted in a lower concentration of ammonia in the small intestine (P = 0.003), indicating reduced protein fermentation. In the small intestine, the high FC content increased the number of lactobacilli (P = 0.047), tended to decrease the number of coliforms (P = 0.063), tended to increase the lactic acid content (P = 0.080), and reduced the concentration of ammonia (P = 0.049). In the colon, the high-FC diets increased the concentration of total VFA (P = 0.009), acetic acid (P = 0.003), and butyric acid (P = 0.018), and tended to decrease the ammonia concentration (P = 0.076). Intestinal morphology and activity of brush border enzymes were not affected by the diet, although maltase activity tended to decrease with increasing dietary FC (P = 0.061). We concluded that an increase in the dietary FC content, and to a lesser extent a decrease in the CP content, reduced ammonia concentrations and altered the microflora and fermentation patterns in the gastrointestinal tract of weaned piglets. However, these effects were not necessarily reflected by an increased growth performance of the piglets.

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This study used a previously developed model to predict herd mean energy balance of the first 12 wk of lactation from test-day information. The predictions were compared with calculated energy balance based on feed analysis and to changes in body weight. Seven independent feeding trials including 43 diets (519 lactations, 254 cows; 1987 to 1996) were used. Conventional diets were discriminated from nonconventional diets by significant differences between mean calculated energy balance of subtrial diets versus control diets. The total difference between group means of predicted minus calculated energy balance was positive throughout the observed lactation period. It was lowest (5 to 9 MJ of net energy for lactation) during negative energy balance of the conventional diets in wk 2 to 7 when 18 to 50% of the total difference was due to random variation. Because of this difference, both predicted and calculated energy balances were compared to body weight change as a reference for true energy balance. Body weight change was adjusted for rumen fill. While calculated energy balance tended to be negative at times when cows gained weight, predicted energy balance was positive. Cows fed nonconventional diets gained weight, while calculated energy balance was extremely negative, whereas predicted energy balance based on test-day information was positive. We concluded that the prediction difference was relatively small when standard rations were used, and that nonconventional rations biased predicted energy balance to a lesser extent than calculated energy balance. Estimating energy balance based on test-day information appears feasible.

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-In this article the disturbing steps in the process leading to the Post Weaning Syndrome (PWS) in piglets and its prevention is discussed from a nutritional point of view. The proposed sequence of disturbing steps in the gut is the following: when weaning occurs at three or four weeks of age, gut development to digest a 'vegetable' diet is immature and the normal gut morphology is disturbed by stress, infection, and a low feed intake. The impaired absorption and digestion increases the amount of undigested substrate and may cause explosive growth of bacteria. The colonization resistance is disturbed and for example Escherichia coli can proliferate. Practical measures regarding feeding strategy and feed composition to counteract these disturbing steps in this process leading towards PWS are discussed. piglets / post-weaning / nutrition / gut development / Escherichia coliRésumé -Une approche nutritionnelle pour la prévention du syndrome de post-sevrage chez le porcelet. Le syndrome du post-sevrage et sa prévention, chez le porcelet, sont discutés d'un point de vue nutritionnel dans cet article. Les troubles du tube digestif après le sevrage conduisant à ce syndrome sont les suivants : avec un sevrage à 3-4 semaines d'âge, le tube digestif est immature pour digérer les aliments végétaux, la morphologie intestinale est perturbée par le stress, les infections et le faible niveau d'ingestion alimentaire. La digestion et l'absorption des nutriments sont altérées, ce qui augmente la quantité de substrat indigestible et pourrait causer un développement bactérien explosif. La résistance à la colonisation est perturbée et les bactéries pathogènes, comme certaines souches d'Escherichia coli, peuvent proliférer. Des mesures pratiques concernant les stratégies alimentaires et la composition des aliments pour contrecarrer ces perturbations sont discutées.

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