The effects of standing time (time for serum separation and blood clotting) on measurement results of biochemical constituents in porcine blood at 4°C were estimated in our present study, and the following findings were obtained.
1) Items in which no difference was observed in measurement results between the samples left for preparation up to 24 hours and those left for 15 minutes were Ca, Mg, ALP, phospholipids, total protein, A/G, γ-fraction and BUN.
2) Items in which the measurement results of the samples left for preparation up to 24 hours showed significantly lower values than those of the samples left for 15 minutes were GPT (after 12 hours), glucose (after 8 hours), and total cholesterol (24 hours).
3) Items in which the measurement results of the samples left for preparation up to 24 hours showed significantly higher values than those of the samples left for 15 minutes were Fe (24 hours), inorganic phosphorus (24 hours), GOT (after 4 hours), LDH (after 4 hours) and triglycerides (after 8 hours).

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Correlated responses of carcass traits to index selection for meet production performance were investigated of six generations of Landrace pigs and their genetic parameters were also estimated. A total of 141 boars and 136 castrated males were used by selecting one each of them from among 22 to 25 litters and 18 to 36 litters of each generation. The results examined on the basis of regression coefficients in terms of carcass lengths and back loin lengths revealed that the lengths of carcass, back loin I and back loin II became significantly shorter by 0.315cm (p<0.01), 0.333cm (p<0.05) and 0.324cm (p<0.01) per generation, respectively, whereas the length of loin eye did not change significantly. The lengths of cervical vertebra (A), thoracic vertebra from the 1st to the 5th (B) and the loin vertebra from the last lumber vertebra to pubic bone (D) were estimated on the basis of differences in the above-mentioned test results. The results suggested that the fore quarters of the carcass became shorter by selection for growth and backfat thickness. Also in the castrated males, the lengths of carcass and the back loin I became shorter by the selection by 0.638cm (p<0.01) and 0.431cm (p<0.01) per generation, respectively, and the length of tha back loin II also tended to become shorter. Although the live backfat thickness became thinner by 0.044cm per generation, the thickness of carcass backfat at shoulder, back, loin and the mean value showed hardly any changes. Genetic and phenotypic correlations between the carcass fat percentage and the live backfat thickness were found to be positive and higher than those between the fat percentage and the backfat thickness of carcasses. Genetic and phenotypic correlations between the fat percentage of carcass and the carcass traits in conjunction with length and eye muscle area were found negative. Converse relationship was found between the protein percentage of carcass and these traits as against the relation between the fat percentage of carcass and the traits.

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In order to investigate the feed efficiency of roughage in Meishan pigs, 26 Meishan pigs and 14 three-way crossbred pigs (produced by F₁ female from Landrace dam and Large White sire × Duroc terminal sire)were fed with feed of three different TDN levels (70, 60 and 50%) during the period from 30kg to 90kg of body weight. The TDN levels were regulated according to the percentage of alfalfa meal. The growth rate, feed intake and feed efficiency of the pigs (with the feed) were investigated.
The results revealed that the mean daily gain was significantly less in the Meishan pigs than in the crossbred pigs (p<0.01), but the mean daily gain in both the Meishan and the crossbred pigs increased as the TDN levels became higher (p<0.01). The ratios of the daily gain with 60% TDN feed to that with 70% TDN feed were approx. 0.9 both in the Meishan and the crossbred pigs. However, the ratios of the daily gain with 50% TDN feed to that with 70% TDN feed was 0.6 in the Meishan pigs and 0.7 in the crossbred pigs. This result means that the feed efficiency of alfalfa meal in the Meishan pigs is lower than that in the crossbred pigs.

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