The present experiment was conducted to evaluate the effects of grain size of corn as one of the principal materials in current years for formula feed upon its digestibility in pigs. Corn grains were ground by a mill equipped with screens with varying mesh sizes of 1mm, 2mm, 3mm, and 5mm, respectively, in the grinding instrument. The corn grains thus ground were added in a ratio of 40% each to the formula feed used for performance test on meat production in Japan in the experimental groups, and the mixed feeds were used as the test feed samples. Five Landrace barrows weighing 32 to 38kg at the beginning of the experiment were each placed in metabolism cages, and the test on digestion was conducted for a preliminary period of 5 days and a feces collection period for 5 days subsequent to it so as to estimate the digestibility of each experimental feed of 5 different kinds as a 5×5 Latin square. The 5 kinds of test feed comprised the group of only the formula feed and 4 other groups of 4 different kinds of formula feeds. These were given to pigs in an amount of 40g per kg of body weight per day, divided equally to each animal and given at about 9a.m. and 3p.m. Sufficient amount of water was also provided to them throughout the experiment. The results were as summarized below.
The average digestibility of each component of the ground corn by mesh size of screen of 1mm, 2mm, 3mm and 5mm was 90.3, 89.3, 88.8 and 87.6% of dry matter, 91.2, 90.1, 89.6 and 88.4% of organic substances, 82.1, 74.9, 73.8 and 70.6% of crude protein, 84.3, 80.5, 74.6 and 66.9% of ether extract, 94.1, 93.9, 93.0 and 92.7% of nitrogen-free extract, 19.5, 22.0, 27.6 and 26.4% of crude fiber, 89.8, 88.2, 87.5 and 85.9% of gross energy and 100.0, 99.9, 99.7 and 99.6% of starch, respectively.
It is suggested therefore that the digestibility of each component of ground corn except the crude fiber tended to be better as the grain size of the corn became smaller.
The digestibility of each component of the corn except that of crude fiber through the treatment with 1mm screen was significantly (p<0.05) higher than that with 5mm screen treatment.
The average nutritive value of the corn by treatment with 1mm, 2mm, 3mm and 5mm screen was 7.7, 7.0, 6.9 and 6.7% in DCP, 4.05, 4.05, 3.94 and 3.93kcal/g in DE and 94.3, 93.1, 92.1 and 90.4% in TDN, respectively. Any of these nutritive values of the material with 1mm screen was significantly higher (P<0.05) than the counterparts of the material with 5mm screen treatment. Both DCP and TDN of the 1mm screen treatment were also significantly higher (P<0.05) than those in 3mm screen treatment.
Therefore, the above-mentioned data can be claimed to be clearly showing that the grain size of the diet is one of the important factors in comparatively evaluating the digestibility and nutritive values of feedstuff with high accuracy because the grain size exerts significant influences upon the digestibility of feed.

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The differences of the nutritive values among the varieties of sweet potato were examined with the digestion trial with pigs and by the in-vitro method using the intestinal fluid of pigs in Experiment 1, and the influences of the processing methods of sweet potato, potato and cassava on the nutritive values were studied with the in-vitro method in Experiment 2.
Four sweet potato varieties, Kyukei 20 and Kyukei 40 bred for use as food and Kyushu 82 and Kogane-sengan bred for use as material for starch, were used for digestion trials after drying in oven. Eight piglets weighing approx. 40kg were used for the in-vivo digestion trial. Once a day, they were given 1200g of either a basal feed or an experimental diet which was prepared by mixing the ovendried sweet potato from each variety with the basal diet in a 1:1 weight ratio. The digestibilities of crude protein (CP) and energy were determined by the chromic oxide method. Digestible energy (DE, kcal/g in dry matter) determined with the in-vitro method for Kyukei 20, Kyukei 40, Kyushu 82 and Kogane-sengan was 3.22, 3.23, 3.63 and 3.49, respectively, the latter two being significantly higher than the former two (P<0.05) A similar relationships was found in DE determined with pigs, but it was not significant (P>0.05); DE with pigs was 3.67, 3.70, 3.87 and 3.82, respectively. The DE of the varieties of sweet potato for starch tended to be higher than that for food use. A close correlation (r=0.99) found in DE between the in-vitro method and the in-vivo method indicates that the in-vitro method gives a good estimate of DE in pigs. Digestible crude protein (% in dry matter) determined with pigs was -0.1, -0.4, 2.3 and 1.7, respectively.
Sweet potato (Kogane-sengan) and potato (Dejima) were freeze-dried, sun-dried, oven-dried or boiled and used for the determination of in-vitro DE in order to estimate DE for pigs. In sweet potato, the estimated DE was 3.66, 3.71, 3.81 and 3.90, respectively, and that in potato was 2.60, 2.75, 2.95 and 3.92, respectively. DE of potato was significantly (P<0.05) improved by boiling. The DE values of boiled sweet potato and those of potato were comparable to those of corn which was 3.87. The estimated DE of cassava with oven-drying was 3.85, which was higher than that of sun-dried one amounting to 3.69 (P<0.05).

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The present experiment was conducted to evaluate the nutritive value of leaf protein concentrate (LPCs) prepared with alfalfa, ladino clover, red clover and mixture of timothy and alfalfa in pigs by extraction and fractionation.
The experimental diets were prepared by replacing 30% of the basal feed which was the formula feed used for meat production as the performance test in Japan with one of the acove-mentioned LPCs so as to determine the digestibility.
Groups of 3-4 Landrace barrows each weighing 30-60kg at the beginning of the experiment were used for the study.
The pigs were given the feed in an amount of 40g per kg of body weight per day. Each pig was kept in a metabolism cage, and the digestion trial was conducted covering a preliminary period of 5 days and feces collection period of 5 days subsequent to it by collecting whole amount of feces. The resulting digestibility of each ration was as described below.
The digestibility of crude protein of LPCs ranged from 56 up to 80% and was inferior to that of soybean meal.
The digestible crude protein content in the dry matter of LPCs ranged from 17 up to 47%, although the DCP of the LPC obtained from the first harvest of alfalfa in the season of 1982 and 1983 had been so good as more than 40%, thus showing a large magnitude of variations. On the other hand, the nutritive value of energy in LPCs was generally lower because of low digestibilities of crude fat and nitrogen-free extract.
The amino acid compositions of the LPCs did not vary so much with their varieties. The concentrations of essential amino acids in the LPCs were higher than those of soybean meal except for arginine.

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