Relationship between the number of viable fetuses (NF), number of corpora lutea (NCL), survival rate of fetuses (SRF) for NCL, number of mummified fetuses (NMF), the length of both uterine horns (LUH), weight of uterine horns (WUH) and records of farrowing were investigated in 50 pregnant sows of Landrace at 111-113 day of gestation. An analysis of multiple regression in which NF, NMF and SRF were taken as dependent variable was carried out. The results obtained were summarized as follows: 1) the means and standard deviation of the values measured at 48h after killing in 21 heads of 1st farrowing sows and 29 heads of 3rd and 4th farrowings sows were NF; 10.6±2.5 heads, NCL; 16.0±2.7, SRF; 68.0±18.0%, NMF; 0.8±1.0 fetuses, LUH; 404.8±76.4cm and WUH; 5.2±1.3kg, 2) the correlation coefficients of NF for SRF, NMF, LUH and WUH were significant, but that for NCL was not significant, 3) the correlation coefficients of SRF and NMF for NCL were significant 4) The correlation coefficients of SRF and NMF for LUH were significant, 5) the partial regression coefficient of NF for LUH was 0.020 heads/cm (P<0.001), however that of NF for NCL was not significant, 6) the partial regression coefficient of SRF was 0.127%/cm (P<0.001) for LUH, -2.545%/corpus luteum (P<0.001) for NCL, 7) the partial regression coefficient of NMF was -0.006 fetuses/cm (P<0.001) for LUH, 0.108 fetuses/corpus luteum (P<0.05) for NCL. From these results, it is concluded that the capacity of uterus for embryo is an important factor to increase the litter size.

View full abstract

The present study was conducted to examine the effects of ad libitum feeding and restricted feeding on the reproductive performances in the gifts and the sows.
In experiment 1, thirty one F1 female pigs (twenty seven LH gifts from six different litters and four LW gifts from one litter) were randomly assigned to three groups; ad libitum feeding group (n=10), ordinary feeding group (n=10) and restricted feeding group (n=11). They were used from 4 months of age with about 50kg of body weight to the age of puberty. The developing gifts in ordinary feeding group were fed on the basis of the Japanese Feeding Standard for Swine until 120kg of body weight. Restricted feeding group was fed 70% of the feed of ordinary feeding group. Ad libitum feeding group was fed with ad libitum. Ages of puberty with 120kg of body weight and first estrus were 206.5±21.0, 223.2±16.5, 302.1±43.4 days and 248.3±18.8, 262.2±25.6, 297.1±37.7 days in ad libitum feeding group, ordinary feeding group, restricted feeding group, respectively. The differences between ad libitum feeding group, ordinary feeding group and restricted feeding group were statistically significant.
In experiment 2, five pigs in ad libitum feeding group, six pigs in ordinary feeding group and eight pigs in restricted feeding group were examined on the reproductive performances from first parity to tenth parity. Ordinary feeding group was fed 2.8kg/day of gestation mash (TDN 67.0%, DCP 9.5%) during the gestation period in each parity. Restricted feeding group was fed 70% of the feed of ordinary feeding group and ad libitum feeding group was fed with ad libitum. During the lactation period, all pigs were given 5.4kg/day of finishing mash (TDN 70.0%, DCP 12.5%). None of the sows in ad libitum feeding group were culled; all of them farrowed until tenth parity without any severe disorders. In ordinary feeding group, three sows were removed from the experiment; one died from a difficult delivery at the first parity and the others were culled because of a difficulty of standing after the fifth parity and a repeated anestrus after sixth parity, respectively. In restricted feeding group, the 6 sows that had abortion or premature delivery were culled; 2 sows in the second parity, 2 in the third parity, 1 in the fourth parity and 1 in the fifth parity. Also one sow in anestrus after weaning after third parity was culled and the other was removed in the halfway of sixth parity because of emaciation.
On the basis of the above results, it is suggested that the emaciation by restricted feeding postpone the attainment of puberty and affect the breeding longevity of sows. It is also suggested that ad libitum feeding does not affect the breeding longevity of sows.

View full abstract

To investigate the factors for establishment of teat-order of newborn pigs, the differences in starting time of milk ejection among teats were measured using four sows.
The summary of the results was as follows: (1) The mean starting time of milk ejection of number 1 teat on the most anterior parts of the body was 1.6 seconds and 4.7 seconds earlier than that of number 3 and 6 teat, respectively. (2) There was no correlation between starting time of milk ejection and milk yield. (3) The suckling behaviour of piglets searching for the teat that ejects milk earlier was considered to be one of the factors for establishing the teat-order of newborn pigs.

View full abstract

To cope with the sharp increasing import of pig meat from other swine industrialized countries, it is indispensable to strengthen the international competitive edge of Japanese pig industry. For this purpose, it is necessary to compare pig production cost of Japan with those of other countries which export pig meat to our country. And so, in this paper, the author would like to analyze pig production costs in Japan, U. S. A., Taiwan and U. K..
In view of pig farming, pig feeding technology and pig farm managerial technics are the most important factors to determine the level of pig production cost in each country.
Hog production cost per liveweight kg in Japan is 2.4 times higher than that of U. S. A., 1.5 times higher than that of Taiwan and 2.1 times higher than that of U. K. on average. In the same way, feed cost per liveweight kg in Japan is 2.6 times higher than that of U. S. A., 1.3 times higher than that of Taiwan and 1.9 times higher than that of U. K.. Similarly, feed price per kg in Japan is 2.8 times higher than that of U. S. A., 1.5 times higher than that of Taiwan and 1.9 times higher than that of U. K.. Neverthless, there is no correlation between pig production cost and feed conversion ratio based on fattening technics. Feed conversion ratio in Japan is rather superior to that in U. S. A.
As mentioned above, the lowest production cost in U. S. A. is due to the lowest feed cost per liveweight kg and the cheapest feed price per kg, whereas Japanese high production cost is due to high feed price per kg. To reduce pig production cost in Japan, it is urgently necessary to take off the restrictions and deregulate the pig feed indutry in order to cut down the feed price.

View full abstract