In order to predict carcass composition from specific gravity, 32 and 28 pigs of the (Landrace × Large White) × Duroc cross were slaughtered at 70 and 108kg live weight, respectively. The carcass was skinned and cut into shoulder, loin-belly and ham. These sections were weighed in air and water to determine carcass specific gravity and dissected into muscle, fat and bone. The means of the carcass specific gravity were 1.04786 at 70kg live weight and 1.04136 at 108kg live weight. The muscle, fat and bone percentage averaged 56.6, 30.5 and 12.5%, respectively at 70kg weight, and averaged 54.1, 35.0 and 10.9%, respectively at 108kg weight. At 70kg weight, the correlations between specific gravity and carcass composition were 0.917 for the muscle percentage and -0.932 for the fat percentage. At 108kg weight, those were 0.929 for the muscle percentage and -0.944 for the fat percentage. The R² values and the residual standard errors were 0.842 and 1.862, 0.864 and 1.308, 0.868 and 1.888, and 0.892 and 1.302 for the muscle percentage at 70 and 108kg weight and for the fat percentage at 70 and 108kg weight, respectively. These results suggest that carcass specific gravity is useful to predict the muscle and fat percentage of the pig carcass.

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The process of development of the testes and epididymides, and the age of the first ejaculation were investigated in 24 Beijing Black boars from 75 to 360 days of age. The results were as follows.
(1) The weight of the testes and epididymides increased rapidly between 90 (39.2±7.8g, 15.1±2.6g) and 165-180 (444.3±81.9g, 86.7±8.2g) days of age, and then increased slowly from 165-180 to 300-360 (735.0±99.0g, 159.8±33.6g) days of age.
(2) Spermatozoa were first found in the section of the seminiferous tubules at 105 days of age. The diameter of the seminiferous tubules reached 234.4±3.0μm and the histological structure of the seminiferous epithelium was completed at 120 days of age.
(3) Spermatozoa were first found in the tail of the epididymis at 120 days of age. The first ejaculation was at 5 months of age.

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In the previous paper, authors made clear by polyacrylamide gel isoelectric focusing (PAG-IEF) that the specific staining for heme protein by peroxidase reaction, in which o-tolidine-one of the bendizine derivatives- was used as substrate, was available for meat species identification (T-Hp method)¹⁾. Fluorene, naphthol and carbazole derivertives are used for peroxidase reaction as the substrates besides bedizine derivertives. In this paper, the peroxidase reaction by SHAW and PRASAD²⁾, in which 3-amino-9-ethylcarbazole was used as substrate, was applied to stain for heme protein on isoelectric focusing gels (C-Hp method) and the availability for identification of raw cattle, horse, pig, goat and sheep meats and the minimum level of detection in mixtures of pig meat with cattle, horse and sheep meat were compared with T-Hp method in previous paper.
The supernatants from fresh meats and binary mixture meats were separated by PAG-IEF using 1.0mm thick PAG plates (120×230mm) containing 3.0% ampholytes in the pH range 5.0-8.0. Gels were stained for heme protein by C-Hp method.
The results obtained in this experiments showed that C-Hp method was able to distinguish between fresh meat from cattle, horse and pig, however, goat and sheep meat could not be differentiated by this method. In detecting different meat species in binary mixture meats of pig with cattle, horse and sheep, approximately 1 to 5% of the contaminating species could be detected by C-Hp method, respectively.
From above results, it was appeared that the heme protein staining of isoelectric focusing gels by C-Hp method for identification of meat species was not at all inferior to T-Hp method.

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Generally, the conception rate and litter size for frozen boar semen are somewhat inferior to those expected for liquid semen. This experiment was performed to clarify the reason why the fertility resulted with frozen-thawed boar semen was inferior.
A total of 55 gilts were inseminated with frozen-thawed boar semen in 5ml straws. As a rule, the 1st artificial insemination (AI) was given at 20-24hr. after detection of estrous and the 2nd AI was given at 6-8hr, after the 1st AI. The ova were recovered on 5-8 days after insemination and examined morphologically under the stereomicroscope. The results obtained are as follows;
(1) The ratio of developing molura or blastocyst to the number of corpus luteum after 5-8 days of insemination was 65.1% for frozen-thawed semen and 92.8% for liquid semen. Of fertilized ova, 78.2% for frozen-thawed semen and 74.4% for liquid semen developed above molura stage.
(2) All of 30 gilts disapppeared thier estrous signs in a half day after last insemination had fertilized ova. Of fertilized ova, 84.8% developed above molura stage.
(3) Gilts which exhibited the estrous sign over a day after last insemination and those lost the signs shortly after the 1st insemination showed a very low fertility and high embryonic mortality.
(4) The rates of chromosomal abnormalities of embryos were not different between frozen semen and liquid semen.
(5) The loss of fetus 25 to 70 days after insemination was 4.7% and not varied with the motility of sperm inseminated in this experiment.
From the above results, it is concluded that main cause of less farrowing rate and litter size in gilts inseminated with frozen-thawed boar semen is the fertilization failure of ovulated ova, but not the embryonic mortality.

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In order to clarify the effect of restricted feeding on the fat accumulation of fattening pigs, the carcass backfat thickness and the carcass cross section fat area percentage were compared. Thirty seven barrows and thirty two silts were divided into two groups of early (30-70kg) and later (70-105kg) fattening periods. Further, the pigs were reared either under ad libitum or one of the three restricted feeding conditions (92, 83, and 75% of ad libitum feeding). The pigs were slaughtered either at 70kg or at 105kg of body weight. The right half carcass was frozen at -30°C, sliced by an electric saw at each thoracic and lumbar vertebra. The each cross section of carcass was photocopied. Also, the fat areas of subcutaneous, intermuscular and side fat at the 5th, 11th, and 13th thoracic vertebra and at the 6th lumbar vertebra were photocopied. The fat area on the photocopy was measured with a digitizer. The each slice of carcass was grounded, and chemically analyzed. Frozen carcasses were sawed. In the early fattening group of barrows, restricted feeding did not affect the subcutaneous backfat thickness either at shoulder, back or loin. However, it significantly affected the backfat thickness at the following four points: 4cm, 6cm, 8cm and 10cm down from the dorsal mid-line at the last rib. Also, the fat area percentage of the 7th through 13th thoracic vertebra, especially the fat accumulation of subcutaneous fat, was affected by the restricted feeding. In the later fattening group, the subcutaneous backfat thickness was not affected by the resticted feeding. However, the fat area ratio in the 1st through 10th thoracic vertebra and that in the 16th through last lumbar vertebra had decreased. This suggests that the fat accumulation in the body of fore and middle quarters decreased. In the gilts, the subcutaneous backfat thickness of the shoulder and that at the point of last thoracic vertebra were affected by the restricted feeding in the both fattening periods. Also, fat area ratio in every thoracic and lumber vertebra, had decreased. Especially, in the early fattening group, intermuscular and side fat had decreased, and in the later fattening group, the subcutaneous fat thickness at the shoulder and intermuscular fat area in the middle quarter had decreased.

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A total of 344 Large White pigs (including 142 gilts and 202 boars) were slaughtered at 90kg body weight to study the relationship of foot base traits, such as foot base area (FBA), inside/outside ratio of foot base area (IOR) and the incidence of foot base lesion, to meat production traits and body measurements. All the pigs were raised in an enclosed pen with the concrete (partially slotted) floor and had an ad libitum access to a 70.1% TDN and 12.7% DCP diet from the time of approximately 25kg body weight till the time of the slaughter. The FBA and IOR in the front foot were larger (P<.01 each) than those in the hind foot. The FBA in the right foot was larger (P<.01) than that in the left foot. Boars had larger (P<.01) FBA than gilts. The FBA was positively correlated with daily gain, carcass length, and shank circumference. It was negatively correlated with backfat thickness and loin eye area. The IOR in hind foot was negatively correlated with ham ratio. The incidence of foot base lesion was 71.5 percent of all the pigs. There were significantly higher (P<.01) incidence in outside toes than in inside toes in both front and hind feet. The pigs with some foot base lesions had smaller (P<.01) FBA than those with no lesion. There seems to be no relationship between the incidence of foot base lesion and meat production traits or body measurements. Heritability estimates for the FBA in front outside, front inside, hind outside and hind inside toes were 0.561, 0.564, 0.423 and 9.495, respectively, using full-sib analysis. Those for the IOR of front and hind foot were 0.475 and 0.354, respectively. The heritability for the incidence of foot base lesion was 0.353 based on the method by LUSH et al. Overall, the results suggest that mass selection for the FBA and IOR is usefull to improve the foot soundness, but it has some problems with loin eye area and ham ratio.

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