The aim of this study is to compare the constituent factors of carcass production cost in the pig farms between low and high income per sow. The data are based on the pig farm business survey by Yamagata Livestock Association from April 1991 to March 1992. They were collected from 39 pig operations and classified into two groups, i. e the high class income per sow and the low class income per sow.
The constituent factors of pig production cost were determined by multiple regression analysis. Stepwise forward regression method was used to select the independent variables. The dependent variable is the production cost of pork carcass per kilogram and independent variables are 26 items such as: feed cost per kg gain, yearly numbers of weaned piglets per sow, yearly frequency of farrowing per sow, feed conversion ratio, etc.
The results of this study are as follows:
1) The multiple regression expression in the high income pig farms was as follows.
Y=1.94X₁-46.11X₂-4.08X₃+3.03X₄-50.77X₅+0.09X₆+688.98 (R=0.970)
where, X₁ is the feed cost per kg gain, X₂ is the yearly frequency of farrowing per sow, X₃ is the raising rate per sow, X₄ is the death rate in hog, X₅ is the feed coversion ratio and X₆ is the fixed assets per sow.
2) The multiple regression expression in the low income pig farms was as follows
Y=2.18X₁+0.0014X₂+0.72X₃-7.04X₄+4.06X₅-119.19X₆+504.62 (R=0.893)
where, X₁ is the feed cost per kg gain, X₂ is the cost of depreciation per sow, X₃ is the yearly replacement rate in sow, X₄ is the yearly numbers of nursing piglets per sow, X₅ is the death rate in hog and X₆ is the feed coversion ratio.

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We investigated, with a 24-hour continuous observation by a video recorder, the effects of intake of the feed-water mixture based on wet/dry feeding on eating behavior of finishing pigs and frequency of trough usage.
The total eating time of a day by use of a ledge-type wet/dry feeder (Wet 1 section (W1)) and a nose-operated flap type wet/dry feeder(Wet 2 section (W2)), in which feed and water were supplied in the same trough, was approx. 60% of that by the conventional ad lib hopper and separate water supply (control section). No significant difference was found between the Wet-Dry section (WD), where only feed was supplied by a wet/dry feeder, and the control section. Significant differences in eating frequency of a day were not observed among the types of feeder. The average eating times in the W1 and W2 were significantly reduced to 50% of the control section, while no time difference was shown between the WD and control section. The effect of number of finishing pigs per feeding space of wet/dry feeders was observed on both total and average eating time. They were significantly reduced as the number of pigs per feeding space was increased. Feeding trough usage rate in W1 and W2 was significantly higher than that in the control section when the number of pigs per feeding space was 15, and significantly lower when the number was 5, while it was not significantly different from that in the control section when the number was 7.5. When the trough was not used, the proportion of time was significantly higher in W1 and W2 than that in the control section, especially longer in the daytime when the number of pigs per feeding space was 5.
From the aforementioned results, it was estimated that in wet/dry feeding, the reasonable number of finishing pigs per feeding space was 8 to 10.

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Two boars (No. 1, No. 2) kept at the Tokyo Metropolitan Livestock Experiment Station showed azoospermia. The semen characteristics of these boars were examined from the period of normal semen production until azoospermia. Boar No. 2 was injected with hCG after developing azoospermia, and the serum concentration of testosterone and the semen characteristics were examined. In addition, the testes of these boars were observed histologically after slaughter.
The azoospermia occured in boars No. 1 and No. 2 at the age of 54 months.
In boar No. 1, the range of sperm concentration was 0.5-2.3×10⁸/ml and the range of total sperm number was 20.0-299.0×10⁸ between 43 and 52 months of age. In boar No. 2, the semen characteristics were normal for 18 days before azoospermia, but the sperm concentration was 1.4×10⁸/ml and the total number of sperm was 224.0×10⁸ on day 8 before azoospermia. Sperm motility changed markedly between 40 and 51 months of age.
The serum concentration of testosterone in boar No. 2 was 13.6, 8.6 and 9.6ng/ml on days 1, 2 and 3 after hCG injection, respectively. The sperm concentration was 0.05×10⁸/ml and 1.96×10⁸/ml, the total number of sperm was 5.0×10⁸ and 166.6×10⁸ at 31 and 81 days after hCG injection, respectively.
The libido of boar No. 1 was normal throughout the observation period. However, that of boar No. 2 was low between 40 and 54 months of age, and was especially decreased from day 31 after hCG injection until slaugther. Histological observations of the testes of boar No. 1 revealed many abnormal seminiferous tubules. The only spermatogonia were mostly restricted to the seminiferous epithelium. However, mature spermatids were found in a few seminiferous tubules in boar No. 1. The testes of boar No. 2 were histologically normal.

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[in Japanese]

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