Due to the development of high-speed and efficient computors of small sizes in recent years, EBV's (Estimated Breeding Values) which account for not only own records but also relatives' records have been used for selection of swine seed-stock. Multiple traits must be simultaneously taken into consideration for swine genetic improvement. For this reason, the selection index method which accounts for the relative economic values of each trait per unit of genetic improvement is required.
In this paper, the economic values per unit of improvement in terms of number of baby pigs born alive (NBA), litter weight adjusted for 21 days of age (LW 21), number of days required for reaching body weight of 105kg (DAY) and back fat thickness adjusted for the body weight of 105kg (BF) are calculated by using the data obtained from swine producers in Japan.
The coefficients of the selection indices for maternal line, rotational line and terminal sire line are calculated with the Japanese economic values. In the U. S. A., the lower the value for BF, the higher will be the indice, while, in Japan, negative quadratic value is adopted; i. e. both overly fat and overly lean carcasses are subject to deduction of economic values.
It was realized that the larger NBA will contribute more in Japan to the economic values than the larger total LW per litter due to the higher costs of feed smaller number of sows per farm labor than the counter-parts in the U. S. A.

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Restriction enzyme cleavage patterns of mitochondrial DNA of the three Chinese breeds, Meishan, Jinhua, and Northeast Minzhu, were compared with those of Landrace and Large White. Preparations of mitochondrial DNA were obtained from fresh testes and digested with nine restriction enzymes, Apa I, Bam HI, Bgl II, Dra I, Eco RI, Eco EV, Pst I, Sca I, and Stu I. The three Chinese breeds showed identical cleavage patterns with all the enzymes, but the patterns of Bgle II, Sca I and Stu I of the Chinese breeds were obviously different from those of Landrace and Large White. Another difference in the Bgl-II patterns was found out between Landrace and Large White pigs. The patterns of cleavage in the Chinese breeds used in the present study are assumed to be probably the same as those of the Japanese wild pigs and Taiwanese native breeds investigated by WATANABE et al.^{13, 14)}.

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Pig embryos were transferred in seventeen recipient gilts by the laparoscopic technique or by the standard midventral surgery method, and the results were comparatively examined.
Donor gilts were given 1000IU each of pregnant mare serum gonadotropin, followed 72 hours thereafter by 500IU of human chorionic gonadotropin, and were then subjected to mating or artificial insemination on the first and the second day of the estrus. On day 6 or 7 (with the first day of estrus being day 0), blastocysts were collected by laparotomy from the uteri of the donors, which were maintained in Dulbecco's PBS (PBS) containing glucose (1mg/ml) and fetal bovine serum (FBS) (10% v/v) at 37°C until the transfer to the recipients.
Recipient gilts used for the laparoscopic technique were fasted for 24 hours, then anesthetized and positioned in dorsal decubitus. Two stab incisions were made 1-2cm each in size to insert the laparoscope and the operating stick. The laparoscope and grasping forceps were then introduced into the peritoneal cavity and the ovary was examined to locate the corpora lutea.
In order to transfer the embryos, the top of one uterine horn was grasped with the forceps and a long (20cm) needle was inserted through the abdominal wall, so that the tip of the needle could reach the uterine lumen. The embryos were then loaded into a vinyl tube connected with a 1ml syringe and transferred through the needle into the uterine lumen along with 0.4ml of PBS containing glucose (1mg/ml) and FBS (10% v/v).
With this laparoscopic technique, 165 embryos were transferred to eleven gilts. Three gilts (27%) which received 14, 14, and 15 embryos by implantation could farrow a total of 26 piglets. Among the recipient gilts that farrowed, the mean embryo survival was 60%.
With the midventral (surgical) technique, 92 embryos were transferred to six guts. Five gilts (83%) which received 14, 15, 16, 18 and 20 embryos could farrow a total of 47 piglets. The mean embryo survival was 58%.
The results demonstrate that the primary advantage of the laparoscopic technique was the safety of the procedure for embryo transfer and the absence of post-surgical adhesions of the internal organs. This technique is applicable to a swine embryo transfer program on general farms where suitable facilities for surgery are lacking.

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