　肥育豚にタンパク質（ＣＰ）含量が低い飼料を給与すると排せつされるふん尿の窒素が減少するが，これを堆肥化した場合の窒素の動態や臭気発生状況は明らかにされていない。そこで，ＣＰ15.0％の標準飼料とＣＰ13.9％の低ＣＰ飼料を給与した去勢肥育豚のふんに同豚の尿を20％混合して水分調整し，小型堆肥化装置による堆肥化試験を行った。その結果，

1)　低ＣＰ飼料を給与した豚ふん尿混合物は標準飼料を給与したものと同等に品温が上昇し，乾物が減少することから，堆肥化への影響はない。

2)　ふん尿混合物の窒素含量は低ＣＰ飼料を給与した方が標準飼料を給与したものより低く，これを堆肥化した時の窒素含量も低い。

3)　飼料中のＣＰ水準を 1ポイント下げた豚のふん尿を堆肥化すると揮発するアンモニア量が半減することから，低ＣＰ飼料給与により堆肥化過程におけるアンモニアガスの大幅な低減が期待できる。

4)　低ＣＰ飼料の給与による堆肥化期間中の硫黄化合物の低減効果は認められなかったが，堆肥化開始時の固形物中の低級脂肪酸量は減少し，ふん尿の臭気抑制効果が示唆された。

　How Providing Pigs with low Protein Diet Affects their Feces Compost - Offensive Smell Emission. KOYAMA Futoshi, Shoichiro YAMAGUCHI, Tetsuya MURAKAMI and Norikazu FUKUDA

　It is possible to reduce the amount of nitrogen contained in the feces from pigs by providing the pigs with low protein (CP) diet.　However, in the case of their feces being composted, it is not clear how much nitrogen stays inside of the compost and how much offensive smell is emitted.

　Therefore, I conducted an experiment utilizing a compact compost production device.　In the experiment, I mixed the dung taken from a castrated pig which had been eating standard diet that contains CP 15.0% in it with the urine taken from the pig.　 And I also mixed the dung taken from a castrated pig that had been eating low CP diet that contained CP 13.9% in it with the urine taken from the pig.　The percentage of urine contained was 20% in each of the feces.　Then I made a water adjustment on each of the feces and proceeded with the experiment.　After I finished conducting the experiment, I confirmed the following results:

1.　The temperature of the mixed substance made of the dung and urine taken from the pig, which had been eating low CP diet, rose to the same temperature of that of the mixed substance made of the dung and urine taken from the pig which had been eating standard diet.　The amount of the dry part in both mixed substances was reduced.　Therefore, whether the diet to be given to pigs is low CP or not, has nothing to do with making the feces compost more efficient.

2.　The amount of nitrogen contained in the mixed substance made of the dung and urine taken from the pig, which had been eating low CP diet, is less than the amount contained in the mixed substance made of the dung and urine taken from the other pig which had been eating standard diet.　Also, the amount of nitrogen contained in the compost made of the former is less than the amount contained in the compost made of the latter.

3.　After the feces, which was taken from the pig that had been eating diet with the CP level of one point less than normal, was composted, the amount of ammonia volatilized from the compost was reduced in half. Therefore, it is possible to expect that the amount of ammonia gas to be emitted in the process of making the feces compose can be greatly reduced.

4.　Although I couldn't confirm any favorable results in cutting the amount of sulfur compound produced from the feces taken from the pig, that was providing with the low CP diet, I confirmed that the reduction in the amount of low-level fatty acid contained in the mixed substance and the effects on reducing offensive smells that came from dung and urine which were evident when providing pigs with low CP diet in the experiment.　