Conceptus development in Large White and prolific Chinese Meishan pigs

Abstract

Large White (LW) and Meishan (MS) gilts were killed on Days 8, 10, 11, 12, 14 and 30 of gestation. Mean diameters (mm) for MS and LW conceptuses, respectively, were: Day 8, 0.45 and 0.69; Day 10, 2.7 and 1.9; Day 11, 5.3 and 2.7, with the differences among days being affected by breed (P less than 0.01). Variation in diameter among conceptuses from LW gilts was greater (P less than 0.01) than that for MS gilts on Days 8-11, respectively: Day 8, 20 and 46%; Day 10, 29 and 38%; and Day 11, 22 and 44%. Conceptuses had elongated in 3 of 5 MS and 1 of 4 LW gilts on Day 11, 6 and 6 MS and 2 of 4 LW gilts on Day 12 and all gilts of both breeds on Day 14. These results indicate that conceptuses of MS gilts develop more rapidly and more uniformly between Days 8 and 14 of gestation. Overall, embryonic survival for Days 8-12 for gilts not having elongated conceptuses was 90.2% for MS and 73.2% for LW gilts (P less than 0.01). On Day 30 of gestation, embryonic survival was also higher (P less than 0.01) for MS (89%) than LW (55%) gilts. However, embryonic weight, crown-rump length, placental length, allantoic fluid volume, amniotic fluid volume, as well as total glucose, fructose and protein in allantoic fluid were not affected by breed. Placental weight was greater (P less than 0.01) for LW gilts. Uterine development at Day 30 of gestation, based on total length and weight of uterine horns, width of uterine horns, total endometrial surface area and total endometrial weight was greater (P less than 0.01) for LW gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive performance in relation to uterine and embryonic traits during early gestation in Meishan, Large White and crossbred sows

“…In common with the genetic study of Haley and Lee (1990) (Wrathall, 1971; present study) and after adjustment to a common ovulation rate, the difference in favour of the Meishan would therefore be about 0.3 in the study of Bazer et al (1988) and 0.15 in the study . Given The relationship between uterine capacity and uterine size is uncertain, and in fact this study confirms that of Bazer et al (1988) (Bidanel et al, 1990b;Haley and Lee, 1990 or in piglet weight (Bidanel et al, 1990b;Haley et al, 1992 (Bidanel et al, 1989;Haley and Lee, 1990). In the study of Haley and Lee (1990) …”

“…In both France (Bidanel et al, 1989) and the UK (Haley and Lee, 1990) (Bolet et al, 1986;Bazer et al, 1988;Bidanel et al, 1990a), whereas studies on the UK Meishan sample have found signifi¬ cantly higher ovulation rates in both gilts and sows than in Large White females Haley and Lee, 1990;Wilmut et al, 1992). With no advantage to the Meishan in ovulation rate, the prolificacy of the French sample compared with the Large White breed is due to enhanced pre¬ natal survival (Bolet et al, 1986;Bazer et al, 1988).…”

“…With no advantage to the Meishan in ovulation rate, the prolificacy of the French sample compared with the Large White breed is due to enhanced pre¬ natal survival (Bolet et al, 1986;Bazer et al, 1988). Prenatal survival in the Meishan breed in the UK is only slightly greater than in the Large White breed (Haley and Lee, 1990).…”

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

“…Puberty occurs at about 3 months, thus much earlier than in European pig breeds (6-7 months). Average litter sizes are 30-40% higher than those of contemporary Large White pigs (Bolet et al, 1986; (Bidanel and Legault, 1986;Bazer et al, 1988; On day 20 of lactation, blood samples (3 ml) were taken for 6 h at 15-min intervals for analysis of LH. On day 22 all sows received an im injection of 15 5 og oestradiol benzoate (OB, Progynon B Oleosum, Schering)/kg body weight.…”

“…All sows were inseminated or mated at least twice during induced oestrus. Pregnancy was tested by echography 4 weeks after insemination or mating (Martinat-Botté et al, 1988).…”