DIGESTIBILITY OF BREWERS’ GRAINS BY SWINE L. Paloheimo and Berit Jahkola Department of Animal Husbandry , University of Helsinki Received March 9, 1959 Arrangement of the experiments The digestion experiment was made with two young pigs (A and B) of the Large White Yorkshire breed. The animals were kept in separate concrete boxes. At the beginning of the experiment the weight of pig A was 62 kg, and 35 days later, at the close of the experiment, 85 kg. The corresponding figures for pig B were 56 and 75. For a period of 3 weeks the animals were gradually accustomed to the experi- mental diet, which consisted of 4.4 kg wet brewers’ grains and 6 kg skimmilk per day per animal. The animals were fed twice daily, at 8.00 and 18.00. No remnants were left. After the meals the troughs were filled with fresh water. The digestibility was determined by the Cr 2 03 ratio technique. Cr2 03 was mixed in the food for 7 consecutive days. During this period samples of faeces were taken every morning. The samples of the last two days were used for the determination of the digestibility. At the beginning of the period one meal rations (2.2 kg) of fresh brewers' grains were weighed for the whole period and put into plastic bags which were kept in a cold room (about O°C). At each meal and for each animal 11 g Cr 2 03 was thoroughly mixed with 2.2 kg brewers' grains in the trough after which 3 kg slightly warmed skimmilk was added and mixed with it. During the preparation the animals had no access to the trough. Results In the evening of December 11th the animals received Cr2 03 for the first time with their food. The faeces collected in the following morning, 14 hours after the meal, contained already traces of the marker. The Cr203 content in the faeces in the 6 following days is shown in Table. 1. The chromium determination was made according to the principle of Paloheimo and Paloheimo (9, p. 317). Beckman spektrofotometer with filter 375 m.fx was used. The samples of faeces collected on 17th and 18th December were analysed. The following determinations were made: Table 1. Cr2 03 content in the dry matter of faeces. Cr2 0, mg/g Date Pig A Pig B 12.12. traces traces 13. 24.6 21.0 14. 29.5 35.5 15. 43.4 42.6 16. 40.2 40.8 17. 43.0 39.7 18. 44.3 42.5 1) dry matter, 2) ash, 3) chromium, 4) crude protein, 5) membrane substances. The magnitude of the following fractions was obtained by calculation: 6) organic matter, 7) N-free organic matter, 8) valuable N-free substances. The amount of membrane substances or vegetable cell wall substances was determined by the method of Paloheimo and Paloheimo (10, p. 1). The fraction »valuable N-free substances» is obtained by subtracting from the amount of N-free organic matter the amount of membrane substances. The same determinations as from the faeces were made from the brewers' grains. From the skimmilk only crude protein and fat were deter- mined in order to confirm that the composition of this product was normal. The crude fibre determination was made from the brewers’ grains for the same purpose. The result of the latter determination was 16.6 % of the dry matter. Data about the composition of the brewers' grains and the faeces are given in Table 2. On the basis of these figures it is possible to calculate the digestibility of the components of the brewers' grains. In this calculation the components of the skimmilk are presumed to be completely digestible. The digestibility was calculated for each animal and for the 6th and 7th days separately. The results are shown in Table 3. Table 2. Data pertaining to the composition of the brewers’ grains and the faeces. Faeces 2 g ls n “ Pig A Pig B 6th day 7th day 6th 7th day day % in Cr2O s -free dry matter: Organic matter 96.80 88.20 88.66 87.71 88.30 Crude protein 21.29 13.19 14.16 15.55 13.20 N-free organic matter 75.51 75.01 74.50 72.16 75.10 Membrane substances 30.23 47.29 42.15 44.29 45.48 Valuable N-free substances 45.2827.72 32.3527.87 29.62 Pro 100 g Cr3Oa-free dry matter Cr2 03 g 2.754.49 4.644.13 4.44 175 176 Table 3. Digestibility percentages for the components of brewers’ grains. Pig A Pigß & B Sjä.g öo bo £ ° ö *„:56th 7th g 6th 7th « >** «f t. £>£ day day day day < < ~£ < ao E m n! o S Organic matter 44.2 45.7 45.0 39.7 43.5 41.6 43.3 > ffl £ Crude protein 62.0 60.6 61.3 51.3 61.6 56.5 58.9 N-free organic matter . . 39.1 41.5 40.3 36.4 38.4 37.4 38.9 Membrane substances . . 4.2 17.4 10.8 2.5 6.8 4.7 7.8 4.5 Valuable N-free substances 62.5 57.7 60.1 59.0 59.5 59.3 59.7 60.» Discussion In this investigation the traditional food analysis has not been followed. Instead of crude fibre determination, the percentage of vegetable membrane substances has been determined. The latter determination results in a group of substances which contains all the cellulose and lignin of the sample together with the major part of the hemicelluloses. The valuable N-free substances constitute fraction of the food which results when the membrane substances are subtracted from the N-free organic matter. The retention time of food residues in the alimentary canal of pigs is rather short. 4 days’ feeding on the experimental diet seemed to be adequate for cleaning the digestive tract of the rest of the preceding diets (Table 1). For safety’s sake the samples of faeces for digestibility determinations were taken as late as on the 6th and 7th days. With the exception of the digestibility coefficient of membrane substances pertaining to pig A in the 7th day, the coefficients obtained for different animals and days are fairly well in agreement with each other and give a distinct picture of the character of brewers' grains as food for pigs. Clawson et ai. (1, p. 700), Moore (6, p. 273; 7, p. 24), and Horvath et ah (4, p. 869) have observed diurnal variations in the composition of swine faeces. Although these variations are not considerable, however, for obtaining a fully representative sample of faeces, it seems to be recommendable to collect the faeces produced on two consecutive days and to take an average sample from this material. In our experiments the samples were taken in the morning on two consecutive days, and each of these samples was used separately for digestibility determinations. As the morning faeces are produced partially in the preceding evening the sampling covers an appreciable part of the 24 hour period, and the samples can be considered sufficiently representative. As mentioned above, the brewers' grains were fed together with skimmilk and the latter food was considered as totally digestible. It is evident that pigs fed on skimmilk alone still produce faeces the origin being chiefly endogenous. There is 177 Table 4. Digestibility percentages of brewers’ grains according to different sources. % in dry matter Digestibility % According to o H S Jn 0) c