Impact of fibre intake and fibre source on digestibility,gut development,retention time and growth performance of indigenous and exotic pigs

The impact of fibre level and fibre source on digestibility, gastrointestinal tract (GIT) development, total tract mean retention time (MRT) and growth performance was studied in indigenous Mong Cai (MC) and exotic Landrace × Yorkshire (LY) pigs. The diets were based on maize, rice bran, soyabean meal, fish meal and soyabean oil, and cassava residue (CR) or brewer's grain (BG) as fibrous ingredient sources in the high-fibre diets (HF) and were fed ad libitum. A low-fibre diet (LF), containing around 200 g NDF/kg dry matter (DM), was formulated without CR and BG as feed ingredients. The HF diets (HF-CR and HF-BG) were formulated to contain around 270 g NDF/kg DM. The experiment was arranged as a 2 × 3 factorial completely randomized design with six replications, and lasted 27 days. Increased dietary fibre level resulted in a reduction (P < 0.05) in average daily gain, digestibility of organic matter (OM), CP and gross energy (GE) at the ileum and in the total tract, and in MRT, and an increase (P < 0.05) in the feed conversion ratio and in the weight of the GIT (except for small intestine and caecum). The coefficients of total tract digestibility of fibre fractions were higher in HF diets than in the LF diet, with highest values for diet HF-CR, which had a high proportion of soluble non-starch polysaccharides. MC pigs had longer MRT of digesta than LY pigs (P < 0.05), resulting in higher digestibility at the ileum and in the total tract. Across diets and breeds, the total tract apparent digestibility of OM, CP and GE was positively related (R² = 0.80 to 0.84) to the MRT of solids, whereas the MRT was negatively related to the DM intake (R² = 0.60).     

Effects of a dietary organic acid mixture and of dietary fibre levels on ileal and faecal nutrient apparent digestibility, bacterial nitrogen flow, microbial metabolite concentrations and rate of passage in the digestive tract of pigs

Six 34-kg barrows were fitted with a post-valve T-caecum cannula and assigned to six dietary treatments according to a 6 × 5 change-over design to study how a mixture of formic acid, sorbate, and benzoate (0 or 8.4 g/kg feed) influences apparent ileal and faecal digestibility coefficients, bacterial nitrogen (N) flow, microbial metabolite concentrations, and passage rate in pigs fed isoenergetic diets with medium, high, or very high fibre content (neutral-detergent fibre (NDF): 199, 224, and 248 g/kg dry matter, respectively). These barley and soya-bean meal based diets contained 0, 75, and 150 g/kg barley fibre (NDF: 577 g/kg) and 0, 8, and 16 g/kg rapeseed oil, respectively. The dietary organic acid mixture improved the apparent ileal digestibility of 14 of the 17 amino acids analysed (P < 0.05). Increasing levels of dietary fibre linearly decreased the apparent ileal digestibility of six of the 17 amino acids analysed (P < 0.05). Ileal flows of bacterial N and amino acids as assessed on the basis of purine flow were decreased by the dietary organic acid mixture (P < 0.05) but were not affected by dietary fibre level (P>0.05). As assessed on the basis of diaminopimelic acid flow, bacterial N flow was increased by both the dietary organic acid mixture and increased dietary fibre levels (P < 0.05). The dietary organic acid mixture reduced the concentration of lactic acid and increased that of acetic acid in ileal digesta (P < 0.05), while dietary fibre levels had a quadratic effect on concentrations of acetic, propionic, and butyric acid (P < 0.05). The mean retention time of Co (solute marker) and Yb (particle marker) in the large intestine decreased in a linear manner by increasing dietary fibre levels (P < 0.05) but was not affected by the dietary organic acid mixture (P>0.05). The results show that a dietary organic acid mixture has a positive effect on the apparent ileal digestibility of most amino acids irrespective of dietary fibre levels. This could be at least partly related to changes in bacterial N flow in the ileum. However, different bacterial markers showed opposite effects on bacterial N flow, which makes it questionable to use a constant bacterial marker / bacterial N ratio to estimate bacterial N flow. Increasing levels of dietary fibre had negative effects on the apparent ileal amino acid digestibilities and shortened the mean retention time of digesta in the large intestine.     

Equine pre-caecal and total tract digestibility of individual carbohydrate fractions and their effect on caecal pH response

The working hypothesis was that a minor postprandial caecal pH decline would affect apparent total tract digestibility (ATTD) of the fibre fraction in horses and, hence, that soluble fibre would amplify fermentation and consequently increase ATTD of fibre. This study was a 4 × 4 Latin Square design with a sequence of 17 days adaptation to the ration followed by 8 sampling days. The feed rations consisted of only timothy hay (Group H), hay plus molassed sugar beet pulp combined with either whole oats (Group OB) or barley (Group BB) and hay plus loose chaff based concentrate (Group M). Four horses fitted with permanent caecal cannulas and collection harnesses were used. A pH electrode with logger was inserted through the cannula and caecal pH was recorded at 1 min intervals for 8 h. The mobile nylon bag technique was used to quantify pre-caecal loss (PCL) of individual feedstuffs. Fibre was analysed as dietary fibre (DF), non-starch polysaccharides, soluble non-cellulosic polysaccharides (S-NCP), insoluble non-cellulosic polysaccharide (I-NCP) and neutral detergent fibre. The ATTD of the S-NCP fraction was above 0.8, which was 60% higher than for the I-NCP fraction. The PCL of starch were 0.98 (oats) and 0.75 (barley). The BB diet lowered (p < 0.001) postprandial caecal pH more than the other diets and a significant correlation was found between the lowest pH and ATTD of I-NCP (r = ?0.66; p = 0.005). In conclusion, this study successfully measured the in vivo digestibility of individual fibre fractions and found that S-NCP was more digestible than the I-NCP, and that a single meal of unprocessed barley was sufficient to decrease caecal pH to such an extent that the fibre digestibility of the whole diet was negatively affected.     

Effect of dietary fibre on nitrogen retention and fibre associated threonine losses in growing pigs

Apart from being an energy source, dietary fibre is also discussed to act as anti-nutritional factor reducing apparent precaecal protein and amino acid (AA) digestibility due to reduced absorption or increased endogenous secretion or both. However, the amounts of protein and AA of endogenous origin determined at the terminal ileum in cannulated animals do not represent the total losses associated with endogenous secretion. A high proportion of secreted protein is reabsorbed and does not reach the terminal ileum, and losses occur during synthesis of endogenous protein. Therefore, the present study used an alternative indirect approach, taking the reduction of nitrogen (N) retention in a threonine (Thr) limited diet as a sensitive indicator for fibre-associated Thr losses. Two experiments were conducted with 12 castrated male pigs each between 37 and 75 kg body weight to measure the effect of the intake of Thr and 150 and 300 g/d fibre from wheat bran (Exp. 1), or 150 g/d fibre from rape seed, cassava leaves, and cassava root peels, respectively (Exp. 2), on N retention. During two (Exp. 1) and three (Exp. 2) balance periods the animals were subjected to the dietary treatments according to a cross-over design. All animals received 1350 g/d of a wheat–soybean-based diet supplemented with free AA to ensure Thr being the first-limiting AA. To determine the effect of Thr on N retention, intake of the basal diet was reduced to 1150 g/d and supplemented with corn starch to reach equal energy intake and an unchanged AA pattern. With increasing BW additional starch was added to all diets to ensure a constant energy intake of 1.25 MJ ME/kg BW^0.75. Since the fibre sources contained small amounts of Thr, N retentions were corrected for precaecal digestible Thr intake originating from the fibre sources according to the Thr effect on N retention as determined in experiment 1. Corrected N retentions were affected by fibre level (p = 0.007) and source (p < 0.001). Fibre-associated Thr losses amounted to 3.3, 3.2, 1.2, and 1.1 g/kg fibre from wheat bran, rapeseed, cassava leaf, and cassava root peel, respectively. It is concluded that Thr losses per gram of dietary fibre depend on the fibre source and that fibre concentration and source in pig diets should be considered as a factor affecting Thr requirement.     

Impact of barley form on equine total tract fibre digestibility and colonic microbiota

This study aimed at assessing the impact of four barley forms on total tract apparent digestibility of dietary fibre in horses fed a large amount of starch in the morning meal (0.27% BW). Processed barley forms had a greater pre-caecal starch digestibility than the whole form. Based on this result, we hypothesised that using barley-processing methods would limit the potential dumping of undegraded starch in the hindgut of horses and, consequently, the potential negative effect on fibre degradation in the hindgut. In a 4×4 latin square design, four mature geldings fitted with a right ventral colon-fistula were fed a meadow hay : concentrate (62 : 38; dry matter (DM) basis) diet at 1.7% BW. The concentrate was made of 80% barley distributed either as whole grain or as processed forms: 2.5 mm ground, pelleted or steam-flaked. For each period, total tract apparent digestibilities of DM, NDF and ADF were determined over 3 consecutive days by total faecal collection, whereas pH, volatile fatty acids (VFA) concentrations and cultural functional bacteria counts (total anaerobic, cellulolytic bacteria, lactic acid producers, amylolytic bacteria and lactic acid utilisers) in colonic content were evaluated on 1 day 4 h after the morning meal. Total tract apparent digestibility of DM and dietary fibre was influenced (P<0.05) by barley form. Diets including thermo-mechanically treated barley forms led to a higher (P<0.05) total tract apparent digestibility of NDF than those constituted of ground barley and also led to a greater (P<0.05) total tract apparent digestibility of ADF than those made of whole or ground barley forms. However, no significant difference was observed in colonic pH, VFA concentrations and cultural bacteria concentrations. Owing to a high starch supply in the morning meal, the concentration of the functional bacteria in the colonic content averaged 7.8 log CFU/ml, 5.9 NPM/ml, 6.9 and 7.3 CFU/ml for total anaerobic, cellulolytic, amylolytic and lactic acid-utilising bacteria, respectively. Consequently, providing horses with pelleted or steam-flaked instead of ground barley forms may limit the negative impact of starch on fibre digestibility in horses fed a high level of starch in the morning meal (0.27% BW). Moreover, the fibre-to-starch ratio fed in this experiment did not cause any digestive upset.     

Influence of dietary fibre level and pelleting on the digestibility of energy and nutrients in growing pigs and adult sows

Two experiments were carried out to investigate the effect of pelleting on the apparent total tract digestibility (ATTD) of energy and nutrients according to the dietary fibre (DF) level in growing pigs (experiment 1) and in adult sows (experiment 2). Four diets based on wheat, barley, maize and soybean meal and supplemented with increased contents of a mixture of wheat bran, maize bran, soybean hulls and sugar beet pulp (116, 192, 268 and 344 g NDF/kg dry matter (DM) in diets 1 to 4) were tested. In experiment 1, 32 growing pigs (62 kg average BW), in two replicates and according to a factorial design, were fed one of the four diets, either as mash or as pellets. The digestibility of energy, organic matter (OM) and all nutrients decreased with DF increasing for both feed forms; the reduction was about 1% for each 1% NDF increase in the diet (P < 0.001). Pelleting improved moderately the digestibility of energy and OM (+1.5% and +1.0%, respectively; P < 0.05) in connection with greater DF (+5%; P < 0.05) and fat digestibility (+25%). Thus, pelleting improved the digestible energy content of diets on average by 0.3 MJ/kg of feed DM (P < 0.01). In experiment 2, four adult dry sows (235 kg average BW) were used in a 4 × 4 Latin square design and fed the four diets used in experiment 1 as pellets. The digestibility of energy, OM and macronutrients also decreased with DF increase (P < 0.001; -0.4% per 1% increase of dietary NDF for energy) while the digestibility of DF (i.e. crude fibre (CF) or ADF) increased (P < 0.001) or remained at a high level. In conclusion, increasing DF in diets decreases the digestibility of nutrients and energy in pigs and in sows. Although positive, the pelleting impact is minor on the energy and nutrients digestibility of fibre-rich diets in growing pigs, even in high-DF diets.     

Barley and oat cultivars with diverse carbohydrate composition alter ileal and total tract nutrient digestibility and fermentation metabolites in weaned piglets

An experiment was conducted to evaluate the effects of cereal carbohydrate form (isolated v. cereal matrix) and level, especially mixed-linked β-glucan (hereafter referred to as β-glucan) and starch amylase/amylopectin ratio on nutrient digestibility and fermentation parameters in the intestines of weaned pigs. Four hulless barley cultivars containing varying β-glucan levels (41 to 84 g/kg) were compared with hulled barley, supplemented or not with a β-glucan concentrate (BBG; 270 g/kg β-glucan) and two oat cultivars for digestibility and fermentation metabolites. Seventy-two weaned piglets (BW = 12.8 ± 1.9 kg) were assigned to one of nine diets composed of 815 g/kg cereal, 60 g/kg whey, 90 g/kg soy protein isolate and 35 g/kg minerals. After 15 days, the pigs were killed, and digesta collected from ileum and colon were analyzed for proximate nutrients, short-chain fatty acids (SCFAs), lactic acid (LA) and ammonia. Ileal and total tract digestibility of proximate nutrients and non-starch polysaccharides (NSPs) were determined using HCl-insoluble ash as a marker. Organic matter (OM) ileal digestibility was greater (P < 0.05) for diets based on hulless barley (77% ± 1.1% on average), as compared with hulled barley (64% ± 1.4%) and oat (58% ± 1.5%). Similar trends were found for total tract OM digestibility, varying from 90% ± 0.3% for hulless barley to 67% ± 0.4% for oat, on average. NSP digestibility differed (P < 0.05) within and between cereal types, ranging from 20% (hulled barley plus 163 g/kg BBG or 40 g/kg β-glucan) to 51% (SB94893 hulless barley cultivar with high β-glucan and high amylose ratio) at the ileum and from 44% (hulled barley) to 84% (SB94893 cultivar) at the total tract level. No dietary effect (P > 0.05) was found for SCFA concentration in ileal contents, whereas in colonic contents, SCFA was lower in pigs fed oat (P < 0.001). LA concentration was greater (P < 0.001) in the colon of pigs fed hulless barley than in pigs fed hulled barley and oat. Expressed per kg carbohydrate (NSP + starch) fermented, the ammonia concentration at the colon was lowest for hulled barley diets (supplemented with β-glucan) and the highest for oat diets. In conclusion, the interaction of both form and level of β-glucan impacted nutrient digestibility and fermentation. Hulless barleys with high soluble NSP such as β-glucan and resistant starch yielded, in general higher SCFA and LA and lower ammonia. Hulless barleys may, therefore, have potential for use in feeding strategies designed to improve gut health in pigs.     

Effect of exercise on apparent total tract digestibility of nutrients and faecal recovery of ADL and TiO2 in ponies

Exercise and physical training are known to affect gastrointestinal function and digestibility in horses and can lead to inaccurate estimates of nutrient and energy digestibility when markers are used. The effect of exercise on apparent nutrient digestibility and faecal recoveries of ADL and TiO₂ was studied in six Welsh pony geldings subjected to either a low- (LI) or high-intensity (HI) exercise regime according to a cross-over design. Ponies performing LI exercise were walked once per day for 45 min in a horse walker (5 km/h) for 47 consecutive days. Ponies submitted to HI exercise were gradually trained for the same 47 days according a standardized protocol. Throughout the experiment, the ponies received a fixed level of feed and the daily rations consisted of 4.7 kg DM of grass hay and 0.95 kg DM of concentrate. The diet was supplemented with minerals, vitamins and TiO₂ (3.0 g Ti/day). Total tract digestibility of DM, organic matter (OM), CP, crude fat, NDF, ADF, starch, sugar and energy was determined with the total faeces collection (TFC) method. In addition, DM and OM digestibility was estimated using internal ADL and the externally supplemented Ti as markers. Urine was collected on the final 2 days of each experimental period. Exercise did not affect apparent digestibility of CP, crude fat, starch and sugar. Digestibility of DM (DMD), OM (OMD), ADF and NDF tended to be lower and DE was decreased when ponies received the HI exercise regime. For all treatments combined, mean faecal recoveries of ADL and Ti were 87.8±1.7% and 99.3±1.7%, respectively. Ti was not detected in the urine, indicating that intestinal integrity was maintained with exercise. Dry matter digestibility estimated with the TFC, ADL and Ti for ponies subjected to LI exercise were 66.3%, 60.3% and 64.8%, respectively, while DMD for HI ponies were 64.2%, 60.3% and 65.2%, respectively. In conclusion, physical exercise has an influence on the GE digestibility of the feed in ponies provided with equivalent levels of feed intake. In addition, the two markers used for estimating apparent DMD and OMD indicate that externally supplemented Ti is a suitable marker to determine digestibility of nutrients in horses performing exercise unlike dietary ADL.     

Effects of betaine and condensed molasses solubles on nitrogen balance and nutrient digestibility in piglets fed diets deficient in methionine and low in compatible osmolytes

Abstract

A balance experiment was carried out to investigate the effects of betaine monohydrate (BET) or betaine derived from condensed molasses solubles (CMS) as a substitute for methionine and choline on nitrogen (N) balance and total tract nutrient digestibility in weaned piglets. The experiment included four treatments with 32 barrows with an average initial body weight (BW) of 13.5 kg. The supplementation of DL-methionine and choline (positive control = PC) to the basal diet, which was deficient in methionine and low in compatible osmolytes in the form of betaine or its precursor choline (negative control = NC) resulted in a significant increase in N retention of 0.8 g/d. The substitution of DL-methionine and choline with BET or CMS did not affect N retention compared to the PC and the NC treatment either. Feeding the PC diet increased the digestibilities of organic matter, NDF, ADF, NFE, crude ash, Ca, P, methionine, tryptophan and cystine by 1.9%, 7.3%, 9.7%, 1.1%, 6.3%, 13.9%, 7.7%, 15.9%, 4.3% and 2.8%, respectively, and tended (p < 0.20) to increase the digestibilities of most other amino acids by 1.6 – 3.4%. Digestibility of CP, EE (HCl), Mg and Na was 3.1% (p = 0.09), 5.1% (p = 0.09), 5.1% (p = 0.06) and 3.3% (p = 0.17) higher, respectively, when compared to the NC treatment. BET and CMS supplementation increased most nutrient digestibilities in the same magnitude as for the PC treatment. In summary, the supplementation of betaine, originating from different sources, to a diet with low contents of compatible osmolytes increased in particular the fermentation of fibre and enhanced mineral absorption. The supplementation of the NC with DL-methionine was more efficient in improving N retention than the replacement of DL-methionine by betaine originating from BET or CMS.     

Apparent digestibility of wheat bran and extruded flax in horses determined from the total collection of feces and acid-insoluble ash as an internal marker

Several studies have reported data on comparisons between two methods: the total collection of feces and the internal markers method. The aim of this study was to assess the apparent digestibility of two concentrates and to compare the apparent digestion coefficients using the total collection of feces and acid-insoluble ash (AIA) as the internal marker method. In 2009, six adult geldings aged between 3 and 11 years, with an average weight per trial of 543, 540 and 542 kg, respectively, were used to determine the apparent digestibility by means of three in vivo digestibility trials on hay, hay plus wheat bran (60 : 40) and hay plus extruded flax (80 : 20). Feces were collected over a 6-day period with a previous 14-day adaptation period. The three digestibility trials were carried out to determine the digestion coefficients of the three diets and, indirectly, of the two concentrates. The digestion coefficients of the diets were determined for the dry matter, organic matter, crude protein and gross energy, whereas the apparent digestion coefficients of the same parameters were calculated for wheat bran and extruded flax, by calculating the difference from the previous results. The data were analyzed using the Student t-test for paired samples. The digestion coefficients obtained were similar when the total collection of feces and the AIA method were used. Higher data variability, confirmed by a greater standard deviation, was observed using the AIA method to estimate the apparent digestion coefficients. It can be concluded that the use of AIA as an internal marker in digestibility trials on average leads to values similar to those obtained with the total collection of feces and can therefore be considered a less-expensive method to determine apparent digestion coefficients. Nevertheless, the total collection of feces should still be considered the best choice to determine the digestibility of some specific feedstuffs.     

Influence of different fibre sources on digestibility and nitrogen and energy balances in growing pigs

Abstract

The present study was undertaken to investigate how three different fibre sources, sugar beet pulp, soya bean hulls and pectin residue, constituting 15% of diets for growing pigs, influenced daily body gain, feed conversion, apparent faecal digestibility and nitrogen and energy balances. Eight castrated crossbreed pigs (30 – 80 kg live weight) were used in a replicated 4 × 4 Latin-square design with one control diet and three fibre containing diets. Daily body weight gain and feed conversion were not affected by the dietary treatments. The apparent faecal digestibility of organic matter (OM) and energy were significantly lower for the fibre diets (OM: 0.81 – 0.85; energy: 0.78 – 0.83) compared to the control diet (OM: 0.88; energy: 0.86). The apparent faecal digestibility of crude protein (CP) was lower for the fibre diets (0.71 – 0.78) compared to the control diet (0.83), although it was only significantly lower for the sugar beet pulp and pectin residue diets. The pectin residue diet, which contained the highest amount of dietary fibre, lignin and insoluble non-starch polysaccharides, had the lowest digestibility of OM, CP and energy. There was a tendency (p = 0.07) for a diet effect on retained nitrogen in proportion to digested nitrogen, where the sugar beet pulp and pectin residue diets had numerically the highest values. Heat production and retained energy in proportion to metabolizable energy intake were not affected by fibre inclusion. It was concluded that the inclusion of sugar beet pulp, soya bean hulls and pectin residue in diets for growing pigs decreased the apparent faecal digestibility and in the diets with sugar beet pulp and pectin residue higher utilization of digested nitrogen for retention compensated for the lower amount of digested nitrogen.     

Differences in mean retention time of sheep and goats under controlled feeding practices

The objective of this study was to compare the mean retention time (MRT): (a) between sheep and goats when they fed in groups with the same diet, the same amount of food and forage to concentrate (F/C) ratio and (b) between group and individual feeding in each animal specie (the same diet, the same amount of food and F/C ratio). Twelve, 3-4 years old, Friesian crossed dairy ewes and twelve, 3-5 years old, Alpine crossed dairy goats were used for the experiment. The animals were fed with a diet, consisted of alfalfa hay, wheat straw and concentrate, in two treatments. In Treatment A the animals fed on a group basis as it is traditionally used in practise, while in Treatment B the diet was offered individually toin each animal, in order to have fully comparable feeding level among animals and between treatments. Each Treatment (A and B) lasted 3 weeks. The results of this study have shown that: sheep had significantly longer rumen retention time (RRT) (30.03 vs. 14.43) and mean retention time (MRT) (40.80 vs. 27.81), and shorter transit time (TT) (8.86 vs. 11.49) than goats, while the caecum retention time (CRT) did not differ between the two species in Treatment A (group feeding). The comparison between group (Treatment A) and individual feeding (Treatment B) in goats or in sheep has shown that there were no significant differences as RRT, CRT, TT and MRT concerns. In conclusion, animal species (sheep vs. goat) was the main factor which affected the MRT, RRT and TT when the animals were fed in groups with the same diet, amount of food and F/C ratio, while the feeding technique (group vs. individual) had no effect on those parameters in both animal species.     

The effect of hydraulic retention time on the stability of aerobically grown microbial granules

AIMS: The aim of this study is to evaluate the effect of hydraulic retention time (HRT) on the development of aerobically grown microbial granules. METHODS AND RESULTS: Five column-shaped sequential aerobic sludge blanket reactors (SASBRs) were seeded with aerobically grown microbial granules and operated in a cyclic mode at different HRTs. At the shortest HRT of 1 h, the strong hydraulic pressure triggered biomass washout and led to reactor failure. At the longest HRT of 24 h, which represented the weakest hydraulic selection in this study, aerobic granules were gradually substituted by bioflocs because of the lower frequency of volumetric exchange. Within the optimum range of HRTs from 2 to 12 h, however, aerobic granules became stabilized in the presence of adequate hydraulic selection in the reactors, with good mixed liquor volatile suspended solids (MLVSS) retention, high volumetric chemical oxygen demand (COD) removal, low sludge volume index (SVI) values, good effluent quality, low sludge production rate, stronger and more compact structures, high cell hydrophobicity and high ratios of extracellular polysaccharides (PS) to extracellular proteins (PN). CONCLUSIONS: HRTs between 2 and 12 h provided the hydraulic selection pressures favourable for the formation and maintenance of stable aerobic granules with good settleability and activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first systematic study on the effect of HRT on heterotrophic aerobic granules. The results of the investigation are useful in understanding how aerobic granules can be applied for wastewater treatment.     

Effects of whole plant brown algae (Laminaria japonica) on zootechnical performance,apparent total tract digestibility,faecal characteristics and blood plasma urea in weaned piglets

ABSTRACT

Two trials were conducted with 48 newly weaned piglets (28 d old) each 8.6 ± 0.05 kg to study how Laminaria japonica plants (LJ) affect zootechnical performance, feed conversion and the apparent total tract digestibility (ATTD) of crude nutrients. All basal diets consisted of cereals, soybean meal, skim milk powder and premixes according to recommendations (no growth promoters or enzymes). For Trial 1, piglets from 16 litters (50% male-castrated, 50% female) were assigned to three treatment groups (n = 16) in a completely randomised block design. Groups received either 2.5% supplementation with sun dried (SD) or drum dried (DD) LJ powder or 2.5% of diatomaceous earth (control). For Trial 2, piglets from 12 litters received either 5% of diatomaceous earth (control) or one of three mixtures of diatomaceous earth + DD LJ powder (3.3%+1.7%, 1.7%+3.3% or 0.0%+5%; n = 12). Data collection included zootechnical performance, faecal consistency, blood plasma urea (Trial 1 and 2) and ATTD (Trial 2). Metabolisable energy (ME) of DD LJ and diets in Trial 2 was estimated using digestible nutrients. Statistical analysis included two-way ANOVA (treatment, block) and mixed linear regression. During both trials, LJ at dosages ≥2.5% significantly reduced feed:gain ratio compared to control (p ≤ 0.0001, = 0.01 for Trial 1, Trial 2) irrespective of the drying method. ATTD from Trial 2 significantly increased digestibilities of dry matter (DM) and crude ash (CA) (p ≤ 0.01) and significantly decreased digestibilities of organic matter and crude fibre in animals fed ≥3.33% DD LJ (p = 0.01). Fractional digestibility of the DD LJ resulted in limited ME of ~9.3 ± 2.5 MJ/kg DM. Dietary conversion ratios of ME and digestible DM of DD LJ diets from Trial 2 decreased linearly with increasing algal supplementation (R² = 0.93, 0.94 and p_slope = 0.002, 0.002 for MCR, DCR). In conclusion, dried LJ powder was included up to 5% into diets without impairing zootechnical performance. The improved feed conversion in the presence of LJ was partly due to slightly higher ME within the algae diets compared to control. However, piglets receiving LJ during Trial 2 needed significantly lower dietary ME and digestible DM to maintain growth performance. Thus, LJ exerted a performance enhancing effect on weaned piglets. The precise mode-of-action is yet unclear.     

Nutrition of captive lowland anoa (Bubalus depressicornis): a study on ingesta passage,intake, digestibility,and a diet survey

Members of the Bovini genus are classified as grazers. Smaller species of ruminants are not expected to be able to digest particularly fibrous diets and are more often classified as intermediate feeders or browsers. Anoas (Bubalus spp.) are interesting in this respect as they are the smallest representatives of the Bovini, being only 10–20% of the body weight of other species of the same genus. A feeding trial was carried out with four lowland anoas (Bubalus depressicornis) at London Zoo, investigating diet digestibility by total fecal collection and passage rates by the simultaneous administration of a fluid (Co‐EDTA) and a particle (Cr‐mordanted fibre <2 mm) marker. The diet consisted of legume hay, dairy cow pellets, browse, fruits, and vegetables. The achieved digestibility coefficients averaged 70±4% for dry matter and 57±7% for cell walls (NDF). Mean retention times for the total gastrointestinal tract were 25±4.1 hr for fluid and 39±6.7 hr for particles, respectively. The ratio of forestomach particle:fluid retention was 2.14±0.40. Additional information regarding anoa diets in captivity was collected through a survey targeting all institutions that have anoas in their collection currently. Suitability of the provided diet was evaluated using the ratio of unstructured:structured feeds (unstructured feeds pellets, grains, produce; structured feeds=roughage, browse) on a dry matter basis and an assumed complete consumption of offered unstructured diet items, with only the remaining intake capacity being met by structured items. The use of this ratio reliably predicted one facility that reported chronic diet‐related problems. As other ruminants, anoas should receive a diet with restricted amounts of concentrates and fruits. The comparatively high fibre digestibility and the high selective particle retention in the forestomach suggest a classification of an intermediate/grazing ruminant. Zoo Biol 24:125–134, 2005. © 2005 Wiley‐Liss, Inc.     

Effects of ileal endogenous nitrogen losses and dietary amino acid supplementation on nitrogen retention in growing pigs

The relationship between ileal endogenous nitrogen (N) losses and N retention was studied in two experiments with growing pigs of 40 to 60 kg. In Experiment 1, 13 ileal cannulated castrated males were fed diets based on maize starch, containing either soyabean meal (SBM) with a low trypsin inhibitor activity (TIA), a mixture of toasted and untoasted soyabean meal with a high TIA (mSBM), a commercial batch of peas, or rapeseed expeller cake (RC). Ileal endogenous N recovery was measured using the ¹⁵N-isotope dilution technique. Apparent ileal digestibility of crude protein (CP) for the SBM, mSBM, pea and RC diets were 82.8, 72.0, 76.7 and 68.7% (P < 0.05). True ileal CP digestibility for the diets was 96.5, 93.0, 94.0 and 87.5% (P < 0.05), and the recovery of ileal endogenous N was 3.08, 6.01, 4.55 and 5.36 g/kg DMI (P < 0.05). In Experiment 2, sixteen castrated males were used to determine N retention, using almost similar diets as in Experiment 1. The diets contained either SBM, mSBM or peas and were balanced for the contents of apparent ileal digestible (ID) CP (96 g/kg) and ID essential amino acids (EAA; at least 85% of requirement values). The fourth treatment was a diet with mSBM as protein source, but supplemented with EAA to the level of 95% of the requirement values (diet mSBMs). Apparent faecal CP digestibility for the SBM, mSBM, pea and mSBMs diets was 88.6, 87.2, 86.1 and 86.0% (P < 0.05). Urinary N excretion and N retention for these treatments were 0.39, 0.59, 0.40, 0.53 (P < 0.05) and 0.87, 0.80, 0.85, 0.84 g/kg^0.75/day (P < 0.05), respectively. Utilization of dietary ID N for N retention were 79.8, 73.3, 78.2 and 77.6% (P < 0.05), respectively. The study showed that increased ileal endogenous N losses are associated with higher losses of urinary N and with a lower N retention. Supplementation of extra essential AA to a diet causing a relatively high flow of ileal endogenous N, may compensate for the lower N utilization under these conditions, and thus limit effects on N retention.     

Modelling the effects of changing retention time on abundance and composition of phytoplankton species in a small lake

1. The phytoplankton community model, PROTECH, was used to model the algal response to changing annual mean retention time in a small lake. 2. Simulations of short retention time with a fixed nutrient load resulted in a reduced chlorophyll concentration. A similar relationship was observed when the simulations were repeated but with inflowing nutrients increased in proportion to river discharge. 3. Longer retention time caused the spring bloom to start earlier and the autumn bloom to persist longer. 4. Changes in discharge of the inflowing river also caused a change in the thermal structure of the lake. This change in thermal structure, in turn, influenced the magnitude and composition of the phytoplankton population, particularly those in the CS‐functional group, such as Aphanizomenon.     

Drinking water chlorination in dairy beef fattening bulls: water quality,potential hazards,apparent total tract digestibility,and growth performance

The first study aimed to evaluate the effect of drinking water disinfection (chlorination: NaClO 15%) and conditioning (acidification: H₃PO₄ diluted 1:5 in water) on water quality, water and feed consumption, apparent total tract digestibility, and its potential hazardous effects on Holstein bulls fed high-concentrate diets. Twenty-four animals (221 ± 20.9 kg of BW, and 184 ± 9.9 days of age) were individually assigned to one of four treatments according to a 2 × 2 factorial arrangement: conditioning (with or without acidification) and disinfection (with or without chlorination). The entire study lasted 210 days. Physicochemical and microbiological water quality, water and feed consumption, haematological and biochemical blood parameters, and apparent total tract digestibility were measured; data were analysed via a mixed-effects model. Chlorination and acidification increased (P = 0.02) free residual chlorine in water, and chlorination reduced (P = 0.01) total coliform and Clostridium perfringens counts in water. Treatment did not affect water consumption, total DM intake, or blood parameters. At the beginning of the study, NDF digestibility decreased (P = 0.04) with acidification, however, this was restored at the end of the study. The second study evaluated the potential benefit of drinking water chlorination and acidification on the performance of crossbred Holstein bulls fed high-concentrate diets under commercial conditions. Ninety-six animals (322 ± 35.0 kg of BW, and 220 ± 14.2 days of age) were allocated into six pens assigned to one of the two treatments: untreated drinking water or drinking water treated with chlorination and acidification for a total of 112 days. Physicochemical and microbiological water quality, water and concentrate consumption, eating behaviour, growth performance, and carcass quality were analysed via a mixed-effects model. Water conditioning and disinfection increased (P = 0.01) free residual chlorine concentration and reduced (P = 0.04) total coliform count in water. Although water consumption and eating behaviour were similar between treatments, water conditioning and disinfection increased average daily weight gain (P = 0.03), BW before slaughter (P = 0.01), and hot carcass weight (P = 0.01). In conclusion, drinking water chlorination and acidification in fattening dairy beef bulls is recommended as it improves growth performance without any detrimental side effects on health or nutrient digestibility.     

Effects of fibre-degrading enzymes in combination with different fibre sources on ileal and total tract nutrient digestibility and fermentation products in pigs

ABSTRACT

The study was conducted to determine effects of a complex of fibre-degrading enzymes (xylanase, cellulase and β-glucanase) on nutrient digestibility, fibre fermentation and concentrations of short chain fatty acids (SCFA) at different parts of digestive tract in pigs fed different fibre-rich ingredients. A total of 36 barrows fitted with T-cannulas in the distal ileum (initial body weight of 41.1 ± 2.7 kg) were randomly allotted to six dietary treatments with three different high-fibre diets including maize bran (MB), sugar beet pulp (SBP) and soybean hulls (SH) with or without supplementation of fibre-degrading enzymes. Enzyme supplementation improved (p < 0.05) apparent ileal digestibility (AID) of dietary gross energy (GE), crude protein, dry matter (DM), organic matter (OM), total dietary fibre (TDF), neutral detergent fibre (NDF) and apparent total tract digestibility (ATTD) of dietary GE, DM, OM, TDF, insoluble dietary fibre (IDF) when pigs were fed MB, SBP or SH diets. When compared to the SBP and SH diets, the AID of GE, DM, ash, OM and NDF in diet MB was higher (p < 0.05), but the hindgut disappearance and ATTD of nutrients, except for ether extract and crude ash, were lower (p < 0.05). Enzyme supplementation increased acetate and total SCFA concentrations in ileal digesta and faeces of pigs. In conclusion, enzyme addition improved IDF fermentation and SCFA concentration in the whole intestine of pigs, and there was a large variation of digestibility of fibre components among MB, SH and SBP owing to their different fibre composition. Therefore, fibre-degrading enzymes should be applied to fibrous diets to improve efficient production of swine, especially considering low fibre digestibility of fibre-rich ingredients.     

Effect of excessive dietary fluoride on nutrient digestibility and retention of iron, copper, zinc, and manganese in growing pigs

Ninety-six crossbred growing pigs were used to evaluate the effects of fluoride levels on growth performance, nutrient digestibility, and the retention of minerals in tissues. Four dietary treatments were formulated by supplementing fluorine (as NaF) to a corn-soybean basal diet (39.75 mg/kg F) to provide the following added fluorine levels: 0, 50 100, and 150 mg/kg fluorine. The results showed pigs of the 100 and 150 mg/kg fluorine-added groups had decreased average daily gain (ADG) and increased feed gain ratio (F/G) compared to the control (p<0.05). Apparent digestibility of protein and calcium in 100 and 150 mg/kg fluorinetreated groups was significantly lower than that of the control (p<0.05). On the other hand, iron, copper, zinc, and manganese levels in most tissues of the 100 and 150 mg/kg fluorine groups were markedly changed compared to the control (p<0.05). However, growth performance, nutrient digestibility, and mineral concentrations in all tissues of pigs were not significantly affected by the addition of 50 mg/kg fluorine (p>0.05). Thus, this study suggested that excess fluoride levels could decrease growth performance and change the retention of iron, copper, zinc, and manganese in pigs.