Measurement of transit time of digesta through sections of gastrointestinal tract of pigs fed with diets containing various sources of dietary fibre (non-starch polysaccharides).

The effects of various sources of dietary fibre (defined as non-starch polysaccharides (NSP] on the transit time (TT) of digesta through sections of digestive tract were measured in pigs of 30-85 kg. The pigs were fitted with simple cannulas in the terminal ileum, caecum and mid-colon. Diets in experiments 1-3 were based on barley, wheat, soya bean meal and fish meal with NSP added in the form of wood cellulose (experiment 1), guar gum (experiment 2), wheat bran, pectin (experiment 3). Lactulose was also included in experiment 3 because of its NSP-like effects. Diets in experiments 4 and 5 were based on starch and casein and contained Phaseoluos vulgaris or Pisum sativum (experiment 4) and sugar beet pulp or wheat bran (experiment 5). Transit time (TT) was measured using 103Ruthenium phenanthroline to label solids and 51Chromium complexed to EDTA for liquids. Samples were taken every 3 h after marker administration for 51 h from all cannulas and the faecal output was collected every 3 h. The values obtained were very variable. The range of TT (h) defined as first arrival of markers and peak marker level was 3-12.2 and 3-12.2 to the ileum, 3-22.3 and 4.5-22.3 to the caecum, 4.5-50.3 and 16.5-48.8 to the colon and 24- less than 51 and 30- less than 51 to the rectum respectively.

Artificial rearing of pigs. 12. Effect of replacement of dried skim-milk by either a soya-protein isolate or concentrate on the performance of the pigs and digestion of protein.

1. Pigs (sixteen/diet) were weaned at 2 d of age and given liquid diets (200 g dry matter/l) during a 26 d experiment. The pigs were fed on a scale based on live weight. Dried skim-milk was the only source of protein in diet U and was partially or totally replaced by a soya-bean isolate (diet B) or a concentrate (diets C and D). Soya-bean protein provided 500, 700 or 350 g/kg total crude protein (nitrogen x 6.25) in diets B, C and D respectively. 2. Performance was similar for diets B and D, but poorer than that of pigs given diet U. The apparent digestibility and retention of N of these diets was similar. Pigs given diet C scoured severely and twelve died. 3. Protein digestion was studied in pigs given diets U, B and D, killed at 28 d of age, at the termination of the feeding experiment. The dry matter content and proportion of N in the digesta in the stomach were reduced in pigs given soya-bean protein. Pepsin concentrations in digesta and stomach tissue were unchanged. 4. The concentrations of trypsin and chymotrypsin in the pancreas were greater in pigs given the soya-bean protein concentrate compared with milk protein, but only the increase in trypsin was significant (P less than 0.01). Digesta from the small intestine of pigs given the soya-bean-protein isolate contained less chymotrypsin (P less than 0.05). There were no differences in the proportion of non-protein-N in the total N in the digesta, suggesting that proteolysis of the milk and soya-bean proteins were equally by 28 d of age.

Artificial rearing of pigs. The effect of different levels of fat, protein and methionine in a milk-substitute diet containing skim milk and soya-bean oil.

1. Protein and energy requirements of pigs weaned at 2 d of age were studied. In Expt 1, three diets with crude protein (CP; nitrogen x 6.38) and fat contents (g/kg dry matter (DM)) of 268, 260 (diet A); 216, 415 (diet B) and 264, 405 (diet C) were compared, with and without a supplement of 2 g DL-methionine/kg. Diets A and B contained skim milk and soya-bean oil only, in different proportions. Casein was added to diet C to equalize the CP content to that of diet A. In Expt 2, diets containing 290 or 315 g CP/kg DM were used with either 310 or 405 g fat/kg. The diets contained different proportions of skim milk, soya-bean oil and casein. The same diets as used in Expt 2 were used in Expt 3 but fed to a scale based on live weight which was 25% less than that used in Expts 1 and 2. 2. Methionine supplementation had no significant effect (P greater than 0.05) on the growth rate or feed: gain ratio of pigs from 2 to 28 d of age. The growth rate of the pigs from 2 to 28 d of age was significantly (P less than 0.05) reduced when they were given the higher level of either CP or fat, with the exception that the effect of fat was not significant (P greater than 0.05) in Expt 3. The reduction in growth rate was associated with a decrease in feed intake. Feed: gain ratios were unaffected (P greater than 0.05) by the level of either CP or fat in the diet. 3. The higher protein level did increase the proportion of CP in the carcass DM (Expt 2 P less than 0.01, Expt 3 P greater than 0.05) and gave an indication, which was not significant (P greater than 0.05), of improved N retention (g/d per kg live weight). The higher dietary fat level increased the proportion of lipid in the carcass DM, and this effect was significant (P less than 0.05) in both Expts 2 and 3. 4. Diets containing additional casein were not fully consumed at the level of feeding used in Expt 2. This effect may be associated with the larger amounts of digesta in the stomachs of these pigs. Some differences in the composition of the digesta in the stomach were observed, but these did not affect the performance of the pigs. 5. It seems likely that either growth rate or feed: gain ratio (g DM consumed/g live-weight gain) can be improved by protein or energy levels exceeding those in a diet containing (g/kg DM) 730 skim milk (265-290 CP) and 310 fat. In this diet, containing (g/kg DM) 6-4 methionine and 3-5 cystine, sulphur amino acid requirements were satisfied.

Artificial rearing of pigs. 5. The effect of different proportions of beef tallow or soya-bean oil and dried skim milk in the diet on growth, feed utilization, apparent digestibility and carcass compostion.

1. Diets containing different proportions of skim milk and fat, either beef tallow or soyabean oil, supplemented with fat-soluble vitamins were given to 2-d-old pigs. Each fat source was used in three diets containing approximately 280, 350 and 420 g fat, and 260, 235 and 210 g protein/kg dry matter respectively. 2. The diets were given as a milk containing 200 g solids/l during a 26 d experiment. The pigs were given the diet at hourly intervals according to a scale based on live weight. 3. Increasing the energy content of the diet, with the accompanying decrease in protein content, had no effect on live-weight gain or feed: gain ratio (g feed dry matter/g live-weight gain) (other than a slight reduction in live-weight gain when beef tallow was used), or on nitrogen retention. However, the fat content of the carcass of the 28-d-old pig was increased, and its protein and ash content were decreased. 4. The apparent digestibilities of the fatty acids ranged from 0-96 to 1-00. The faeces from pigs given the soya-bean-oil diets contained some eicosanoic, docosanoic and tetracosanoic acids, presumably of bacterial origin. In general, palmitic and stearic acids were slightly less well digested than oleic and linoleic acids.