To investigate the impacts of uterine type and conceptus genotype on development through late gestation, Meishan and Yorkshire embryos were co-transferred into the uteri of either Meishan or Yorkshire recipients that were subsequently slaughtered on Day 90 of gestation. At slaughter, regardless of conceptus genotype, fetuses and placentae were markedly smaller when recovered from Meishan than from Yorkshire recipients. Whereas Meishan and Yorkshire fetuses recovered from Meishan uteri were similar in weight, Meishan fetuses were markedly lighter than littermate Yorkshire fetuses when recovered from Yorkshire uteri. Because of the marked differences between fetal weights observed in Yorkshire recipients on Day 90 of gestation, Meishan and Yorkshire embryos were co-transferred to Yorkshire recipients that were allowed to farrow. Surprisingly, Meishan and Yorkshire fetuses cogestated in Yorkshire recipients were born at similar weights, whereas Meishan placentae were markedly smaller. The weight of Meishan placentae were similar on Day 90 and at term, whereas the weight of Yorkshire placentae were markedly larger (approximately 70%) at term than on Day 90. The constant weight of Meishan placentae from Day 90 to farrowing appears to result from an ability to increase their vascularity during this interval. In contrast, Yorkshire placentae may be forced to increase their weight to keep pace with fetal growth during this period. Because uterine capacity sets the upper limit on litter size, the decreased endometrial surface area required per conceptus in the Meishan pig seems to explain its greater potential for increased litter size.

Three experiments were conducted to examine the in vitro development of preimplantation embryos from the prolific Chinese Meishan pig. Experiment 1 was conducted to assess whether Meishan embryos would develop in vitro and retain their viability, whereas Exp. 2 and 3 examined the developmental pattern of Meishan embryos. In all three experiments, Yorkshire embryos served as a contemporary comparison. Ovulation and embryo recovery rates were not different between Meishan and Yorkshire gilts. Meishan embryos cultured for 96 h were capable of establishing pregnancies. The number of cell nuclei present after 144 h of culture was lower (P < .01) for Meishan than for Yorkshire blastocysts. Meishan preimplantation embryos exhibited a slower (P < .02) in vitro rate of development from the four-cell to the compact morula stage than did Yorkshire embryos. Early blastocysts from Meishan gilts, although morphologically similar in size, contained fewer (P < .06) cells than did their counterpart Yorkshire embryos. These data demonstrate that Meishan embryos develop more slowly and contain fewer cells than do Yorkshire embryos. This differing developmental pattern of Meishan preimplantation embryos, if similar to that previously reported in miniature swine and mice, may relate to increased embryo survival.

A reciprocal embryo transfer study with Meishan and Yorkshire pigs was conducted to examine the influence of embryonic genotype and uterine environment on preimplantation embryonic growth and development. Embryos were collected from gilts on d 2 of a spontaneous estrous cycle (d 0 = onset of estrus), transferred to synchronous recipients, and collected from recipients on d 12 to obtain measurements of embryonic diameter (size) and embryonic DNA, protein, and estrogen content. No difference was detected between Meishan and Yorkshire donors for number of ovulations, number of embryos recovered, or number of cells per embryo. Embryonic genotype affected (P < .01) d-12 embryonic characteristics; Meishan embryos (n = 101) were smaller (4.7 mm diameter) and contained less DNA (4.5 micrograms) and protein (104 micrograms) than Yorkshire embryos (n = 85; 5.9 mm, 6.1 micrograms, and 149 micrograms, respectively). Embryos (n = 80) transferred into a Meishan uterus were reduced (P < .001) in diameter (4.2 vs 6.4 mm) and in DNA (3.2 vs 7.2 micrograms), protein (103.8 vs 149 micrograms), and estrogen (352 vs 1,643 pg) content compared with embryos (n = 106) transferred into a Yorkshire uterus. These data indicate that the increased prolificacy of the Meishan breed may be due to an increased embryonic survival resulting from slower growing embryos and a suppressive effect of the uterus on embryonic growth rate and estrogen secretion.

The objectives of this research were to determine the effects of beta-mercaptoethanol (beta-ME) and fetal bovine serum (FBS) on in vitro development of bovine embryos derived from oocytes matured and fertilized in vitro and to examine the mechanism through which beta-ME may influence embryo development. A 2 x 2 factorial treatment arrangement was used to evaluate the effect of 0 or 100 microM beta-ME and 0% or 10% FBS on embryos cultured in Medium 199 (M199) in the absence of somatic cells. Embryos were randomly allocated within stage of development (< 8 cells or 8-16 cells) to one of four treatment combinations and were cultured for 6 days. Both beta-ME and FBS promoted increased (p < 0.01) development of embryos to the blastocyst stage, and their effects were greater (p < 0.01) in 8- to 16-cell embryos than in embryos having fewer than 8 cells at the initiation of treatment. The cysteine and cystine content of M199, with and without beta-ME, were determined by HPLC. Medium supplemented with beta-ME contained neither cysteine nor cystine, and it is suggested that these compounds were converted into a mixed disulfide between cysteine and beta-ME. These results indicate that beta-ME is capable of enhancing bovine embryo development in a cell-free, serum-free culture system.

Query (Q) fever is a globally distributed zoonotic disease caused by Coxiella burnetii, a bacterial agent for which ruminants are the most prevalent natural reservoir. Data regarding Q fever infection in camels in Algeria are limited. Therefore, a survey to detect seroprevalence of C. burnetii antibodies was conducted among healthy camel populations in a vast area in southeastern Algeria to determine distribution of the Q fever causative organism and to identify risk factors associated with infection. Between January and March 2016, blood samples were collected from 184 camels and serum samples were subsequently analysed using a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit. At the time of blood collection, a questionnaire investigating 13 potential predisposing factors associated with C. burnetii seropositivity was completed for every dromedary camel and herd. Results were analysed by a chi-square (χ2) test and multivariate logistic regression. The seroprevalence of C. burnetii at the animal level was 71.2% (95% CI: 65.2–78.3) and 85.3% (95% CI: 72.8–97.8) at the herd level. At the animal level, differences in seroprevalence were observed because of herd size, animal age, animal sex, presence of ticks and contact with other herds. A multivariable logistic regression model identified three main risk factors associated with individual seropositivity: (1) age class > 11 years (OR = 8.81, 95% CI: 2.55–30.41), (2) herd size > 50 head (OR = 4.46, 95% CI: 1.01–19.59) and (3) infestation with ticks (OR 2.2; 95% CI: 1.1–4.5). This study of seroprevalence of C. burnetii infection in camels in Algeria revealed a high seroprevalence of Q fever in camel populations in southeastern Algeria and provided strong evidence that Q fever represents an economic, public health and veterinary concern. Appropriate measures should be taken to prevent the spread of C. burnetii and to reduce the risk of Q fever in farm animals and humans in this agro-ecologically and strategically important region of North Africa.