The physico-chemical properties of nutrients in£uence the physical characteristics of faeces and thus may a¡ect waste removal e⁄ciency. The aim of this study is to assess the e¡ect of type of non-starch polysaccharide (NSP) on digesta viscosity, faeces recovery and nutrient digestibility in Nile tilapia. Insoluble (cellulose) and soluble (guar gum) NSPs were included separately and combined at a level of 8%, thereby formulating four experimental diets. The diets were assigned to 16 tanks with 35 ¢sh each, with four replicates for each diet. Cellulose inclusion did not in£uence digesta viscosity, growth and digestibility of protein and starch and tended to increase faeces recovery (P 5 0.06). Guar gum inclusion increased digesta viscosity and reduced the growth and digestibility of protein, fat and starch (Po0.01). Faeces recovery was reduced by 42% in diets containing guar gum. There were interaction e¡ects (Po0.05) between cellulose and guar gum for the growth and feed conversion ratio, indicating that cellulose alleviated the negative impact of guar gum. In conclusion, dietary soluble NSPs increase organic matter load in the culture system through a reduction in faeces recovery and nutrient digestibility, whereas insoluble NSPs improve the removal e⁄ciency of particles by increasing faeces recovery.

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The objective of the present study was to investigate if dietary soluble non-starch polysaccharides (NSP) increase digesta viscosity, reduce nutrient digestibility and increase organ weights in African catfish. The fish (mean weight 80 g) were fed diets supplemented with the soluble NSP guar gum at three levels, 0 g kg )1 (GG0), 40 g kg )1 (GG4) and 80 g kg )1 (GG8). Guar gum inclusion significantly increased digesta viscosity in the proximal (GG0: 1.7 centipoise or cP; GG4: 84.9 cP; GG8: 98.3 cP) and distal (GG0: 1.9 cP; GG4: 109.8 cP; GG8: 66.4 cP) intestine. Apparent digestibility coefficients (ADC) were significantly lower for the GG8 diet than the GG0 diet (dry matter: 52% versus 69%; protein: 77% versus 90%; ash: 41% versus 54%; energy: 60% versus 77%). The ADC of dry matter and energy were significantly lower for the GG4 diet than the GG0 diet. The relative growth rate of metabolic weight (14.5-15.4 g kg )0.8 day )1 ) and feed conversion ratio (0.8) did not differ between diets. Fish fed the GG8 diet had a significantly higher somatic stomach index than GG0 fish (0.71% versus 0.65% body weight). The intestinal somatic index tended to increase with increasing guar gum supplementation (GG0: 1.08%; GG4: 1.23%; GG8: 1.59%). In conclusion, high digesta viscosities in the guar gum fed fish may explain the observed reduced nutrient digestibilities and increases in digestive organ weights. KEY WORDS

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The objective of this study was to investigate if litters with different genetic merit for piglet survival differ in late fetal development. In total, 507 fetuses from 46 litters were delivered by Caesarean section at, on average, d 111 of gestation. All litters had known estimated breeding values for piglet survival (EBVps). The obtained range of EBVps of the litters was continuous, and the difference between litters with the lowest and highest EBVps was 16.4%. Analysis of relationships between fetal characteristics and EBVps was performed with litter averages, using linear regression analysis with inclusion of EBVps as a covariate. An increase in EBVps of the litter was associated with decreases in average placental weight (P = 0.01) and within-litter variation in placental weight (P = 0.02), and an increase in average placental efficiency (P = 0.08). Average fetal length decreased with increasing EBVps (P = 0.04), but weights of liver (P = 0.02), adrenals (P = 0.0001), and small intestine (P = 0.01) showed relative increases with increasing EBVps. Average serum cortisol concentrations increased with increasing EBVps (P = 0.0001), but the other blood characteristics (hematocrit, glucose, fructose, albumin, estradiol-17beta) were not related to EBVps. Glycogen concentrations in liver (P = 0.07) and longissimus dorsi muscle (P = 0.04) and total liver glycogen content (P = 0.05) increased with increasing EBVps, whereas heart glycogen concentration decreased with increasing EBVps (P = 0.005). The percentage of carcass fat increased with increasing EBVps (P = 0.05). Relationships of relative liver weight, relative small intestinal weight, and liver and muscle glycogen levels with EBVps were absent after adjustment for differences in cortisol levels between litters. The observed differences in fetal development in relation to EBVps suggest a higher degree of physiological maturity in litters with high EBVps. Differences in fetal cortisol most likely accounted for most of these maturational differences. The results imply that selection for improved piglet survival will lead to slightly smaller piglets that nevertheless have an improved ability to cope with hazards during birth or within the first days of life.

This study investigated in vitro fermentability of wheatderived carbohydrates using inocula of Nile tilapia and European sea bass. Distal intestinal contents were incubated in bottles containing one of four fermentable substrates, i.e. glucose (GL), native wheat starch (WS), arabinoxylan (ABX) and whole wheat (WHT). Cumulative gas production was measured for 168 h. At the end of incubation, fermentation end-products were measured. A monophasic model was fitted to the gas production profiles of each bottle, thereby allowing calculation of gas kinetic parameters. Total gas production (mL g )1 organic matter) differed significantly between substrates for tilapia (GL: 268.9; WS: 388.0; ABX: 411.9; WHT: 413.2) and sea bass (GL: 338.6; WS: 189.3; ABX: 296.3; WHT: 264.0). Fermentation rates were highest for GL and lowest for WS, both for tilapia and sea bass. Fermentation of ABX and WHT yielded predominantly acetic and butyric acid, whereas GL and WS yielded also significant amounts of lactic acid. Ammonia (mL g )1 organic matter) was highest for WHT (tilapia: 80.36; sea bass: 70.39) and lowest for GL (tilapia: 46.01; sea bass: 32.83). In conclusion, intestinal microbes from Nile tilapia and European sea bass have the potential to ferment carbohydrates. Large differences exist in fermentability and composition of fermentation endproducts between carbohydrates. KEY WORDS