Effect of feeding fermentable fibre-rich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs

Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibre-rich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or 25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on “boar” taint reduction in female pigs.     

Effect of feeding fermentable fibre-rich feedstuffs on meat quality with emphasis on chemical and sensory boar taint in entire male and female pigs

Skatole, androstenone and other compounds such as indole cause boar taint in entire male pork. However, female pigs also produce skatole and indole. The purpose of this experiment was to minimise boar taint and increase overall impression of sensory quality by feeding entire male and female pigs with fibre-rich feedstuffs. The pigs have been fed three organic diets for either 1 or 2 weeks prior to slaughter of which two diets contained different fermentable fibre-rich feedstuffs – 10–13.3% dried chicory roots or 25% blue lupines. These two treatments were compared with pigs fed with an organic control diet for either 1 or 2 weeks prior to slaughter. Lupines significantly reduced skatole in blood and backfat for both genders after 1 week. Moreover, lupines showed negative impact on growth rate and feed conversion whilst chicory showed no significant differences in this respect. However, the indole concentration was significantly lower in chicory than lupine fed pigs. From a sensory perspective, chicory and lupine feeding reduced boar taint since odour and flavour of manure related to skatole and urine associated to androstenone were minimised. The level of boar taint in the entire male pigs was most effectively reduced after 14 days by both fibre-rich feeds while lupine had the largest influence on “boar” taint reduction in female pigs.     

Ruminal nitrogen metabolism and the passage of amino acids to the duodenum in sheep receiving diets containing hay and concentrates in various proportions

Three sheep fitted with rumen cannulas and three sheep fitted with duodenal re-entrant cannulas in addition to rumen cannulas were given, in successive periods, 700 g d^?1 of five diets consisting of chopped hay and a concentrate mixture of rolled barley and flaked maize (50:50) in the ratios of 1:0, 5:2, 3:4, 1:6, and 0:1. For bacteria isolated from the rumen of sheep fitted with rumen cannulas only, there were no significant differences in either the content of nitrogen in their dry matter or in the amino acid composition, but the content of α-?-diaminopimelic acid varied significantly (P < 0.05) between diets, mean values ranging from 39 to 50 kg^?1 nitrogen. As the proportion of concentrate in the diet increased, the intake of nitrogen was progressively reduced from 11.9 to 9.8 g d^?1 and this was accompanied by an increase in the amount of organic matter apparently digested in the rumen, from 296 to 402 g d^?1. But there were no significant differences between diets in either the ruminal concentration of ammonia-nitrogen (mean values varied from 78 to 96 mg litre^?1) or in the duodenal passage of total nitrogen, which ranged from 12.1 to 14.7 g d^?1 with a peak value for the 5:2 diet. Rates of synthesis of bacterial protein in the rumen were 186, 228, 124 and 94 g crude protein per kg organic matter apparently digested in the rumen for the 1:0, 5:2, 3:4, 1:6 and 0:1 diets respectively, the rates for the 1:6 and 0:1 diets being significantly (P < 0.05) lower than those for the other diets. The 0:1 diet was associated with a low proportion, 0.5, of bacterial protein in the duodenal crude protein and it is suggested that with this diet, protozoal protein made an appreciable contribution to the crude protein passing from the rumen.     

Effect of feeding different diets on the exocrine pancreatic secretion of nitrogen,amino acids and enzymes in growing pigs

Five barrows were fitted with permanent pancreatic re-entrant cannulas to determine the influence of diet on exocrine pancreatic secretions in the weight range from 40 to 65 kg. The pigs were fed four diets. Diets 1 and 2 were based on corn starch and contained 18.6 and 16.9 % crude protein (dry matter basis) from soybean meal and canola meal, respectively. Diets 3 and 4 contained 93.9 % wheat and barley, respectively. In the same order, the crude protein contents (dry matter basis) of these diets were 14.4 and 11.2%, respectively. The experiment was carried out according to 4 × 4 Latin square design. Each experimental period comprised 12 days. Following an adaptation period of 8 days, pancreatic juice was collected from 08:00 on day 9 to 08:00 h on day 10 and from 08:00 on day 11 to 08:00 h on day 12. The pigs were fed twice daily, at 08:00 and 20:00 h, 800 g each meal. Despite large differences, up to 23%, between the overall mean values of the parameters that were measured there was no effect (P > 0.05) of diet on the volume of secretion of pancreatic juice, the pH and the secretion of total and TCA-precipitable nitrogen. Due to the high level of within-study variation there was also no effect (P > 0.05) of diet on the secretion of amino acids and the total activity of trypsin, chymotrypsin, α-amylase and lipase in pancreatic juice.     

Exocrine Pancreatic Secretions in Young Pigs Fed Diets Containing Faba Beans (Vicia faba) and Peas (Pisum sativum): Nitrogen,Protein and Enzyme Secretions

Two experiments were carried out to investigate the effect of feeding diets containing faba beans and peas on pancreatic secretions in young pigs fitted with a pancreatic pouch re-entrant cannula. In Experiment 1, eight barrows, with an average initial weight of 8·5 kg, were fed one of two maize starch-based diets formulated to contain 200 g crude protein (CP) kg⁻¹ according to a completely randomised design. In one of the diets, soya bean meal was the sole protein source; in the other diet, soya bean meal and faba beans (cv Fibro; dark-flowering) each supplied 50% of the dietary CP. In Experiment 2, five barrows, with an average initial weight of 18·1 kg, were fed one of two diets according to a two-period change-over design. The diets were formulated to contain 150 g CP kg⁻¹ with peas (cv Ascona or cv Radley) as the sole protein source. In both experiments, the experimental periods consisted of 8 days: 6 days adaptation followed by a 2 day collection of pancreatic juice. The soya bean meal diet and the faba bean diet contained 0.04 and 0.21% tannins (catechin equivalents), respectively. The trypsin inhibitor activities of the Ascona and Radley pea diets were 0·76 and 3·24 mg of trypsin inhibited per gram, respectively. In both experiments, diet did not affect ( P> 0·05) the pancreatic secretions of nitrogen, protein, amylase, lipase and chymotrypsin. In Experiment 1, specific trypsin activity was higher ( P< 0·05) in pancreatic juice from pigs fed the diet containing soya bean meal and faba beans (53700 units litre⁻¹) than for those fed the soya bean meal diet (41200 units litre⁻¹). However, there was no effect ( P> 0·05) when trypsin activity was expressed as total activity (units 24 h⁻¹). It is concluded that the inclu-sion of faba beans and peas in diets for young pigs has only minor effects on exocrine pancreatic secretions.     

Evaluation of a duodenal cannula for dairy cattle

Two dairy cows fitted with rumen cannulas and closed T-shaped duodenal cannulas were utilized to examine duodenal cannula function and indigestible marker performance. Cows were fed one of two mixed diets and hay separately twice daily. Diets contained sources of supplemental protein that differed in expected rate of ruminal degradation. Duodenal DM flow was estimated with the indigestible markers, Cr-mordanted cell wall, Yb-soaked whole crop oat silage, and Co-EDTA. Duodenal DM flow using Co-EDTA was 49% higher than that estimated by reference to Cr-mordanted cell wall; Yb estimated an intermediate flow. Results are interpreted to suggest that the system developed to estimate duodenal digesta flow was not completely successful. However, qualitative assessment indicates that results are substantially better than those previously observed with simple gutter-type T-piece duodenal cannulas. Application of biological tests to the results suggests the failure of the system was not a result of cannula failure per se but due to the method of indigestible marker administration. Cows fed rumen-degraded proteins (slow versus rapid) had higher rumen nonammonia N pools, a trend for higher forestomach fiber fermentation, and a trend for lower forestomach digestion of N. These results are consistent with current knowledge of the influence of slowly degraded proteins on rumen fermentation.     

Exocrine Pancreatic Secretions in Young Pigs Fed Diets Containing Faba Beans (Vicia faba) and Peas (Pisum sativum): Concentrations and Flows of Total,Protein-Bound and Free Amino Acids

Two experiments were carried out to investigate the effects of feeding diets containing faba beans and peas on the concentration, flow and composition of total, protein-bound and free amino acids (AA) in pancreatic juice collected from young pigs fitted with a pancreatic pouch re-entrant cannula. In Experiment 1, eight barrows, with an average initial weight of 8·5 kg, were fed one of two semi-purified diets formulated to contain 200 g kg⁻¹ crude protein (CP) according to a completely randomised design. In one of the diets, soya bean meal was the sole protein source; in the other diet, soya bean meal and faba beans (cv Fibro; dark-flowering) each supplied 50% of the dietary CP. In Experiment 2, five barrows, with an average initial weight of 18·1 kg, were fed one of two diets formulated to contain 150 g kg⁻¹ CP with peas (cv Ascona or cv Radley) as the sole protein source. There was no effect (P>0·05) of the diet, 8 h sampling period or experimental period on the concentration (mM), composition (% and g 16 g N⁻¹) and flow (mmol 24 h⁻¹) of total, protein-bound and free AA or on the percentage of protein-bound AA in pancreatic juice. The concentrations of total, protein-bound and free AA were higher in pancreatic juice collected from younger pigs in Experiment 1 than in pancreatic juice collected from older pigs in Experiment 2. However, the daily flows of total, protein-bound and free AA in pancreatic juice were similar in both experiments. The percentages of protein-bound AA in pancreatic juice were similar in both experiments. In conclusion, the concentrations, compositions and flows of total, protein-bound and free AA in pancreatic juice were not affected by diet, 8 h sampling period or experimental period.     

Recovery at the terminal ileum of some legume non‐nutritional factors in cannulated pigs

In order to exert an effect, either local or systemic, putative beneficial dietary substances have to survive at least to some extent the digestive process within the gastrointestinal tract. For that purpose, five castrated male pigs (100 ± 2 kg mean live b.w.) fitted with T‐shaped ileal cannulas were used to determine the recovery up to the terminal ileum of various non‐nutritional factors (NNF) from legumes (defatted soybean, raw lupin, raw chickpea and raw or autoclaved kidney beans). Kidney bean lectin (PHA) recovery within the small intestine ranged between 2.5 and 4.8 mg from 5.96 mg ingested. Two different methods were used to determine ileal digestibility of protease inhibitors (PI) in pigs. According to the enzyme‐linked immunosorbent assay (ELISA) method, apparent digestibility of Kunitz trypsin inhibitor and Bowman–Birk inhibitor for pigs fed the defatted soybean‐based diet were 0 and 58%, respectively. On the other hand, the apparent digestibility of PI along the small intestine, expressed in terms of trypsin inhibitory activity, was 96, 98 and 95% of activity in the diet, while data expressed in terms of chymotrypsin inhibitory activity were 95, 99 and 79% of activity in the diet for defatted soybean, raw chickpea and autoclaved kidney bean diets respectively. Differences found in ileal digestibility values of PI using both methodologies, ELISA and enzymatic inhibition, might be explained by the detection of inactive forms by specific antibodies. Intestinal apparent digestibility of phytate was 0% for defatted soybean and autoclaved kidney bean diets, whereas values for raw lupin and chickpea diets were 4.1 and 24.5%, respectively. In conclusion, significant amounts of several NNF survived the passage through the stomach and small intestine of cannulated pigs, which might have biological relevance. Copyright © 2006 Society of Chemical Industry     

Ileal digestibility of defatted soybean,lupin and chickpea seed meals in cannulated Iberian pigs: I. Proteins

Five castrated male Iberian pigs (100 ± 2 kg body weight) fitted with T‐shaped cannulas at the terminal ileum were used to determine ileal digestibility of legume seed meals. The diets were based on defatted soybean, lupin or chickpea seed meals and contained similar levels of digestible energy (14.2–15.1 kJ g^?1) and protein (107 g kg^?1). Protein‐free and a hydrolysed casein diets were used to study endogenous ileal amino acid flows. Chromium oxide (10 g kg^?1 diet) was added to the diets as an indigestible marker. Ileal flows in pigs fed the hydrolysed casein diet were different (p < 0.05) in amino acid contents and composition from those on the protein‐free diet. Ileal sialic acid flows in pigs fed lupin‐ or chickpea‐based diets were higher (p < 0.05) than those of animals fed soybean or casein diets. Among essential amino acids, only the apparent ileal digestibilities of phenylalanine and valine in lupin meal were lower (p < 0.05) than those in soybean. Apparent ileal digestibilities of lupin aspartate and proline, together with chickpea aspartate, were also lower (p < 0.05) than those of soybean. True ileal digestibility of nitrogen in pigs fed lupin or chickpea meals, calculated according to values from animals fed the protein‐free diet, was lower (p < 0.05) than that for soybean or casein. Among individual essential amino acids, only the true ileal digestibility of phenylalanine in lupin was lower (p < 0.05) than that in soybean. True ileal digestibility of nitrogen calculated according to values obtained with pigs fed a hydrolysed casein diet was not different among soybean, lupin or chickpea meals. Among essential amino acids, only the true ileal digestibilities of isoleucine and lysine in chickpea were lower (p < 0.05) than those of soybean. It is concluded that true ileal nitrogen and amino acid digestibilities of lupin and chickpea meals are comparable to those of defatted soybean in Iberian pigs. The results with protein‐free diets tended to underestimate endogenous protein secretion in pigs fed on diets containing protein. Copyright © 2005 Society of Chemical Industry     

Influence of method of administration of rapeseed oil in dairy cows. 1. Digestion of nonlipid components.

The effects of rapeseed oil supplements on ruminal digestion and total tract digestibility of nutrients were studied in four cows in midlactation, fitted with ruminal cannulas and used in a Latin square design (three periods x three diets). Treatments were basal diet only (control) or 1 kg of rapeseed oil added to a basal diet by continuous infusion or by a single administration via the ruminal cannula. The ratio of forage: concentrate of the basal diet was 68:32 on a DM basis. Total lipid contents were 3.9, 9.4, and 9.4% of DM in control diets and in diets with continuous and single supplementation, respectively. Fat supply decreased total tract OM digestibility (77.0, 72.0, and 74.0% in control diet and in diets with continuous and single supplementation, respectively) because of a depressive effect on fiber digestion. With both oil administration methods, the relative proportion of propionic acid increased and acetic and butyric acids in ruminal fluid decreased. Moreover, continuous infusion of oil increased the proportion of propionate and decreased the proportion of butyrate. When oil was added as a single administration, ammonia N concentration before feeding was lower than when oil was infused continuously.     

The diurnal pattern of ileal dry matter and endogenous ileal nitrogen flows in the growing pig

The aim was to examine the diurnal pattern of endogenous nitrogen flow at the terminal ileum of the pig. Seven entire male pigs with a mean body weight of 58 kg had post‐valve T‐caecum (PVTC) cannulae surgically implanted for the collection of ileal digesta. The pigs were fed equal‐sized meals (10% of metabolic body weight, W^0.75, per day) twice daily at 08:00 and 17:00. The semi‐synthetic diet included enzyme‐hydrolysed casein (<5000 Da, 100 g kg^?1 diet) as the sole source of nitrogen (N). The diet also contained chromic oxide (6 g kg^?1) as an indigestible marker. The pigs received the diet for an 8 day period, and digesta were continuously collected for 24 h periods (commencing at 08:00) on the fifth and eighth days. Digesta were analysed for dry matter (DM) and chromium (Cr), and endogenous N was determined in the precipitate + retentate fraction of the digesta following centrifugation and ultrafiltration (10 000 Da molecular weight cut‐off). The concentration of Cr expressed on a digesta DM basis and the ratio of endogenous N to Cr in the digesta were relatively constant over the 24 h digesta collection periods, with no statistically significant (P > 0.05) differences found for the latter measure in the digesta collected between 12:00 and 08:00. The endogenous N flow through the terminal ileum is the net effect of the secretion and reabsorption of endogenous N that occurs throughout the digestive tract. The net result of the latter two processes in the small intestine of the pig leads to a relatively constant endogenous N flow over time post‐feeding. © 2002 Society of Chemical Industry     

A comparison of the extent and site of energy and protein digestion of wheat,lupin and meat and bone meal by pigs

The ileal digestibilities of dry matter (DM), nitrogen (N), energy and amino acids were measured using pigs prepared with either re-entrant or simple ileal cannulae and fed a basal wheat diet, a wheat/lupin diet and a wheat/meat and bone meal (MBM) diet. The same pigs were also used to determine the faecal digestibilities of DM, N and energy in these diets. Addition of lupins to the basal diet had no significant effect on the true digestibilities of amino acids but addition of MBM significantly ( <0.01) reduced amino acid digestibility. It was calculated that an average of about 90% of the amino acids in lupin and wheat but only 65% of those in MBM were absorbed from the stomach and small intestine of the pig. Compared to lupin and wheat, a much larger proportion of the protein in MBM disappeared in the large intestine (approximately 4, 6 and 15% respectively). On the other hand, a large proportion of the energy in lupins but little of that in wheat and MBM (32, 8 and 4% respectively) disappeared in the large intestine. There were no significant differences between the re-entrant and simple cannulae for ileal digestibility values of DM, N and amino acids.     

Response of pancreatic secretions to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of soybean trypsin inhibitors (SBTI) on exocrine pancreatic secretions in growing pigs. Six barrows with an average initial body weight (BW) of 27·1±1·4 kg were fitted with permanent pancreatic re-entrant cannulas and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g kg⁻¹ crude protein from either Nutrisoy (food grade defatted soy flour) or autoclaved Nutrisoy. The concentrations of SBTI in Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 9 days each. The average BW at the start of the first and second experimental periods was 33·5±2·7 and 37·2±3·7 kg, respectively. The average BW at the conclusion of the experiment was 41·8±3·9 kg. The volume of pancreatic secretion was higher (P<0·01) when the Nutrisoy, as opposed to the autoclaved Nutrisoy diet was fed (3804 vs 2634 ml (24 h)⁻¹). The concen-tration of nitrogen and protein and specific activities (units litre⁻¹) of amylase, chymotrypsin and trypsin were lower (P<0·05) in pancreatic juice of pigs fed the Nutrisoy diet. There were no differences (P>0·05) in the total secretions of nitrogen (g (24 h)⁻¹) and total activities (units (24 h)⁻¹) of amylase, lipase, chymotrypsin and trypsin in pancreatic juice of pigs fed the Nutrisoy and autoclaved Nutrisoy diets. However, the total secretion of protein was slightly higher (25·7 vs 22·8 g (24 h)⁻¹; P<0·05) in pancreatic juice of pigs fed the autoclaved Nutrisoy diet, which corresponded with the increase in the secretion of protein-bound amino acids. There was also an increase in the total secretion of free amino acids in pancreatic juice. These studies show no effect of SBTI on the total enzyme activities in pancreatic juice of growing pigs. © 1998 SCI.     

Availability of macro and microelements from edible domestic waste fed to sheep

Young Awassi rams fitted with rumen cannula and T-shaped cannulas in duodenum and terminal ileum were used to study net absorption of calcium, phosphorus, magnesium, zinc, manganese, and copper from edible domestic waste in comparison with a conventional concentrate diet. Mean net absorptions (% of intake) of calcium, phosphorus, and magnesium from edible domestic waste and control diets were 15.3, -.9; 54.4, 37.0; and 46.4, 58.8. The small intestine was the major site for calcium and phosphorus absorption and the rumen for absorption of magnesium. Net absorption of zinc, manganese, and copper was low in both diets, probably as a result of excessive supply and low physiological demands. There was a net gain of manganese and copper and a net loss of zinc in the stomachs. In addition to potential for energy and protein, edible domestic waste supplies macro and microelements for ruminants, and thus, it can be regarded as a complete concentrate diet.     

In vivo degradation of protein in diets formulated for two degradabilities.

In vivo protein degradability of two basal diets and bacterial protein synthesis were determined in four lactating dairy cows equipped with ruminal and duodenal cannulas. The diets contained corn silage, high moisture corn, and either soybean meal or a 60:40 mixture of soybean meal and corn gluten meal. Diets had calculated ruminal protein degradabilities of 69.3 and 62.3%, respectively. Both diets contained approximately 14% CP and 21% ADF. Duodenal flows of total N, total protein N, microbial N, and duodenal recovery of ingested N tended to be higher for the soybean meal and corn gluten meal diet; ruminally degraded CP was significantly lower than for the soybean meal diet. Ruminal ammonia and plasma urea concentrations tended to be higher for the soybean meal diet, as were molar percentages of butyrate and valerate. Ruminal and total tract apparent digestibilities of CP and OM were not significantly different between diets. Ruminal degradation of protein in the two diets differed by the amount predicted by the NRC system for lactating cows, although absolute values were lower than most previous estimates for similar diets.     

The use of the alkane technique to estimate diet selection of sheep grazing grass–clover/heather–gorse vegetation communities

The n‐alkane technique was evaluated for estimating the diet composition of sheep grazing in heathlands. Six dietary treatments, composed by different proportions of herbaceous (Lolium perenne and Trifolium repens) and woody species (Erica umbellata, Erica cinerea, Calluna vulgaris and Ulex gallii) were offered to 24 sheep housed in metabolism crates. Diet composition was estimated from alkane concentrations in diet and faeces, by least‐squares procedures, using all available alkanes (C1) from C₂₅ to C₃₃, or only those with higher concentration (C2): C₂₇, C₂₉, C₃₀, C₃₁ and C₃₃. Additionally, the effect of applying mean treatment faecal recoveries (R1), mean faecal recoveries of all experimental diets (R2) or no faecal recovery correction (R3) was studied in both selections of alkanes (C1 and C2). No significant differences were observed between the use of all alkane information (C1) or limited number of alkanes (C2) in the diet composition calculations. There were no significant differences between measured proportions of dietary components and those estimated with procedures R1 and R2. In contrast, the proportions calculated with R3 procedure differed significantly (P < 0.05) from the measured proportions, overestimating feeds with higher content of long chain n‐alkanes. The results indicate that correction of faecal alkane concentrations to allow for incomplete faecal recovery is necessary in order to obtain accurate estimates of diet composition, using mean treatment faecal recoveries (R1) or mean faecal recoveries of all experimental diets (R2). Copyright © 2006 Society of Chemical Industry     

Palm kernel meal as the major protein concentrate in the diets of pigs in the tropics

Three trials were carried out to determine the suitability of locally produced palm kernel meal (PKM) as the major protein concentrate in the diets of weaners, growers and fattening pigs in the tropics. Large White and Large White×Land-race cross barrows and gilts were used. These were individually fed at semi-restricted levels the various diets formulated to contain approximately 15, 12 and 16.5% crude protein for trials 1, 2 and 3 respectively, the PKM or other protein sources contributing at least 50% of the total dietary protein in all the diets. In trial 1, pigs on the PKM diet grew at a lower rate, had poorer feed: gain ratio and protein efficiency ratio and lower feed consumption than the pigs on other diets. Pigs on a fish meal diet (FM) had the best performance throughout. In trial 2, the same trends as for trial 1 were observed, except that pigs on the dried skimmed milk (DSM) diet performed better than those on all other diets. In trial 3, the pigs on the PKM diet supplemented with 10% groundnut cake or 15% DSM had slower growth rate and lower feed:gain ratio than the pigs on other diets containing lower quantities of PKM supplemented with fish meal (FM) or blood meal (BM).     

The effect of housing system on apparent digestibility in pigs,using the classical and marker (chromic oxide,acid-insoluble ash) techniques,in relation to dietary composition

The present study examined differences in faecal digestibilities of organic matter (dOM) and crude protein (dXP), between growing pigs housed either in pens as groups or individually in metabolism cages. In addition, a study was made of the influence of dietary composition on these observed differences. Four experimental diets were composed by iso-energetic exchange of maize starch in the control diet with purified cellulose (260 g kg^-1), toasted soyabean hulls (280 g kg^-1) or renderers fat (67 g kg^-1), respectively. Both in pens and in metabolism cages, dOM and dXP were measured, using both chromic oxide (Cr₂O₃) and acid-insoluble ash (AIA) as markers. In metabolism cages, the results of the marker method were compared to those of the classical method, where dOM and dXP were measured by collecting faeces quantitatively. Recoveries of both markers were measured, after a period of 10 and 3 days. With Cr₂O₃ as marker, pen-housing resulted in a dOM which was on average 2.5 (1.7–4.5) units lower and a dXP averaging 4.5 (3.0–5.8) units lower than measured in the metabolism cages (P≤0.001). No significant interactions were demonstrated between housing system and dietary composition. In contrast, with AIA as marker significantly higher digestibility values were observed for pigs in pens, when fed the cellulose diet. With this diets, the dOM was on average 14.7 units higher and the dXP was on average 10.9 units higher for the penned pigs. For the pigs fed one of the other three diets, the dOM was on average 1.5 (0.1–2.7) units lower and the dXP was on average 3.7 (1.9–5.7) units lower. Thus, with AIA as a marker, the effect of housing system on digestibility interacted with the type of diet (P≤0.05 on dOM and P≤0.01 on dXP). Comparison between the marker method with the classical method, showed that Cr₂O₃ provided similar results. In contrast, AIA displayed significantly higher dOM and dXP, except with the cellulose diet. This could be explained by differences in the recoveries of both markers. For Cr₂O₃ this was close to 100% and for AIA it varied from 97% on the cellulose diet to 183% on the control diet. The analytical procedure for AIA requires more research. Shortening the measuring period from 10 to 3 days did not prove to be significant, but increased the standard deviations. It was concluded that for practical application, faecal digestibilities should be measured with penned pigs. According to the findings, under such conditions Cr₂O₃ is a good marker. AIA was found to be unsuitable.     

凹凸棒石黏土对生长育肥猪生产性能、金属含量及肉品质的影响

研究凹土原土及热改性凹土对生长育肥猪生产性能、金属含量和肉品质的影响。选用体重约47kg健康"杜×长×大"三元杂交的生长育肥猪60头,随机分为3组,每组4个重复。对照组饲喂基础日粮,试验组饲喂在基础日粮中添加2%凹土原土、2%热改性凹土的试验日粮。结果表明:1)凹土原土和热改性凹土对生长育肥猪生产性能无显著影响(P0.05);2)凹土原土和热改性凹土降低血液中As、Pb、Cr含量和腿肌中Cr的含量(P0.05),热改性凹土显著提高血液中Mg含量(P0.05);3)凹土原土降低眼肌MDA(P0.05),凹土原土和热改性凹土降低眼肌中T-AOC的活性(P0.05);4)凹土原土提高眼肌p H45 min、a*45 min(P0.05),降低L*45 min、b*24 h和压力损失(P0.05)。添加凹土原土和热改性凹土能降低重金属在动物机体中的沉积、提高抗氧化能力进而改善肉品质,热改性凹土效果优于原土。     

Investigation of the cholesterol-lowering action of insoluble fibre derived from the peel of Citrus sinensis L. cv. Liucheng

A water-insoluble fibre-rich fraction (WIFF) was isolated from the peel of Citrus sinensis L. cv. Liucheng. The effects of a WIFF-containing diet on lipid and cholesterol absorption in hamsters were investigated and compared with those of a cellulose-containing diet and fibre-free diet, as controls. Results demonstrated that WIFF could significantly (P<0.05) decrease the levels of serum triglyceride, serum total cholesterol, liver total lipids, and liver cholesterol, while it could also significantly (P<0.05) increase the levels of fecal total lipids, fecal cholesterol, and fecal bile acids, as well as the fecal bulk and moisture. The pronounced hypocholesterolemic and hypolipidemic effects of WIFF might be attributed to its ability to enhance cholesterol and bile acids excretion. These results suggest that WIFF could be a potential cholesterol-lowering ingredient in human diets or new formulations of fibre-rich functional foods.