An experiment was conducted to determine the effect of feeding reduced CP, amino acid-supplemented diet on the excretion of urine and nitrogen, and the ammonia emitted from urine and feces in growing pigs. Twelve pigs (35kg BW) were fed corn-soybean meal diets containing either 16.4% CP (standard CP diet) or 10.9% CP supplemented with amino acids (low CP diet) for 28d. After 8d of feeding of the diets, a 4-d nitrogen balance trial was conducted. Ammonia emitted from urine, feces and the mixture, in which feces were mixed with urine (ratio of 1:2, wt/wt) to form a slurry, was determined by an in vitro system on the feces and urine excreted, on the 28th d. Body weight gain, feed intake and feed efficiency were similar between the pigs fed the standard CP diet and pigs fed the low CP diet. Water intake and excretion of urine tended to be lowered by feeding the low CP diet. Feeding the low CP diet reduced the excretion of fecal nitrogen (P<0.10) and urinary nitrogen (P<0.01), and the total excretion of nitrogen in the urine and feces (P<0.05) by 28, 50 and 38%, respectively. Ammonia emitted from the mixture of urine and feces was reduced (P<0.01) by 64% in the pigs fed the low CP diet compared with pigs fed the standard CP diet. We conclude that reducing the CP content in diets reduces fecal and urinary nitrogen excretion and ammonia emission from the slurry of growing pigs.

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We investigated the effects of addition of dried apple pomace to a corn-soybean meal-based diet (standard diet) on the fecal and urinary nitrogen excretion in growing pigs. Eight barrows (BW approximately 40kg) were allotted to two treatments of four pigs each, in which the standard diet or the diet supplemented with 30% of dried apple pomace to the standard diet was given. The pigs were placed individually in the metabolism cages. After a 9-d pre-experimental period, urine and feces were quantitatively collected daily, for a 5-d period. The pigs fed the dried apple pomace-supplemented diet excreted 36% less nitrogen in urine and 104% more nitrogen in feces than the pigs fed the standard diet. However, the total nitrogen excretion was not affected by the dried apple pomace supplementation to the standard diet (P>0.05). Apparent CP digestibility of the dried apple pomace was -106.1%.

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The speed of sexual maturity is an important factor in the economy of swine industry and in the improvement of swine. In this report observations were made of sexual maturities of males and females of Chinese breed, which is of Asian origin, and known as a descendant of Sus vittatus, and has been useful for establishment of various breeds of swine. The results were compared with those of four improved breeds, originated from Sus scrofa. Total 528 swine (84 Chinese, 237 Middle Whites, 106 Berkshires, 66 Large Whites and 35 Poland Chinas) were used. Anatomical, histological and physiological investigations were carried out on the male reproductive organs, epididymal spermatozoa and ejaculates. In the females, age of appearance of first estrus (with ovulation) was determined.
The results are summarized as follows.
In the males:
1) Marked development of reproductive organs was observed during 4-8 months of age in the improved breeds, whereas it was during 2-5 months in the Chinese ones.
2) Detachment of the tip (free part) of penis occurred during 114-248 days of age and 24.0-65.0kg of body weight in the improved breeds, whereas it was during 55-100 days and 4.6-16.0kg in the Chinese ones.
3) Marked development of diameter of seminiferous tubules was observed during 4-6 months and it reached 200μm at 7-8 months of age in the improved breeds, whereas it was during 2-3 months and reached 200μm at 4 months of age in the Chinese ones.
4) The earliest age for the initiation of spermatogenesis was about 120 days after birth and 27-35kg of body weight in the improved breeds, whereas it was 40 days and 4.2kg of body weight in the Chinese ones.
5) Marked inerease of number of seminiferous tubules containing spermatozoa and degree of spermatogenetic activity were observed during 4-5 months and reached constant levels at 5-6 months of age in the improved breeds, whereas increase was seen from 2 months and reached constant level at 3 months of age in the Chinese ones.
6) First ejaculate was obtainable during 151-255 days of age and 32.0-78.5kg of body weight in the improved breeds, whereas it was during 84-133 days and 10.2-19.5kg in the Chinese ones.
In the females:
1) Age of appearance of the first estrus (with ovulation) was 194-328 days after birth and 52.0-120.0kg of body weight in the improved breeds, whereas it was 147-191 days and 17.9-36.5kg in the Chinese ones.
2) Some gilts, 172 days of age and 19.4-31.3kg of body weight, conceived at the first estrus and farrowed 9 (8-11) pigs in the Chinese breeds.
These results show that the age of sexual maturity comes much earlier in the Chinese breeds than in the improved ones.

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