An experiment was conducted to examine the effects of sex and market weight on performance, carcass characteristics and pork quality. A total of 224 crossbred pigs (initially 26.64 kg BW) were allotted in a 2×4 factorial arrangement in a randomized complete block (RCB) design. The variables were sex (gilts and barrows) and different market weights (100, 110, 120 and 130 kg). Average daily gain (ADG) and average daily feed intake (ADFI) were significantly higher (p<0.01) in barrows than gilts, ADFI and feed conversion ratio (FCR) increased as body weight increased (p<0.05). Gender differences were observed in carcass characteristics. Backfat thickness and drip loss were greater in barrows (p<0.01), while loin eye area (p<0.01), flavor score (p<0.05) and lean content (p<0.001) were higher in gilts. Carcass grade and water holding capacity were the highest in 110 kg market weight pigs. The 100 kg market weight pigs showed lower juiciness, tenderness, shear forces and total palatability than the other market weights (p<0.01). Hunter values (L*, a* and b*) were increased as market weight increased (p<0.05). Hunter a* value was greater in gilts (p<0.01) but L* value and b* value were not affected by sex of pigs. Net profit [(carcass weight×price by carcass grade)-(total feed cost+cost of purchased pig)] was higher in gilts than barrows (p<0.01), and was higher (p<0.05) in the pigs marketed at 110 and 120 kg market weight compared with 100 kg market weight. These results demonstrated that gilts showed higher carcass characteristics, pork quality, feed cost per kg body weight gain and net profit compared with barrows. Moreover, 110 or 120 kg body weight would be the recommended market weight based on pork quality and net profit for swine producers.

Arsenic exposure through drinking water can impair the learning and memory ability of children in China and other countries. Synaptic plasticity plays a key role in the process of learning and memory. Alterations in the expression of presynaptic and postsynaptic proteins can be used to evaluate synaptic plasticity, and further to evaluate impairment in learning and memory ability. Thereby, the aim of this study was to explore the mechanisms underlying arsenic neurotoxicity by focusing on alterations in the hippocampal synapses of mouse offspring induced by developmental arsenite exposure. Mother mice and their offspring were exposed to 0, 25, 50 or 100 mg L arsenite via drinking water from the first day of gestation until postnatal day (PND) 35. The spatial learning and memory ability of PND 35 mice was evaluated using a Morris water maze. The levels of speciated arsenicals in the brain of PND 7, 14, 21 and 35 mice were analyzed by hydride generation coupled with atomic absorption spectrophotometry. Synaptic structure and protein expression of postsynaptic density protein-95 (PSD-95) and synaptophysin (SYP) in the hippocampus of PND 7, 14, 21 and 35 mice were examined. The findings from this study disclosed that the spatial learning ability of mice could be impaired by exposure to 25 mg L arsenite; however spatial memory ability could not be impaired until exposure to 100 mg L arsenite. The thickness of the postsynaptic density (PSD) decreased, whereas the width of the synaptic cleft widened significantly in arsenite exposure groups. Moreover, protein expression of both PSD-95 and SYP decreased significantly in arsenite exposure groups. In conclusion, the results of this study demonstrated that developmental arsenite exposure could depress the expression of synaptic proteins, subsequently cause alteration in synaptic structures, and finally contribute to arsenite-induced deficits in spatial learning and memory ability in mouse offspring.

Abstract Background As the COVID-19 outbreak influenced teaching in China, Chinese medical colleges and universities carried out massive online education with the participants of more than one million students on the for-profit or non-profit big–data teaching platforms, based on existing online teaching resources and other ways such as MOOC, Micro-course, Live-course and interactive discussion. Methods A questionnaire survey was conducted via two rounds of 56-in-total questions on overall situations, platforms, teaching methods, training, teachers and students’ experiences, and encountered problems for 1747 teachers and 7223 students, which involved 741 courses. Comparative analysis was done on the survey results. Results A majority of teachers and students were satisfied with teaching platforms and effects; large commercial teaching platforms could provide better services; 67.21% of teachers and 64.67% of students preferred live teaching; only 76.84% of teachers and 58.69% of students were systematically trained; weak network, lack of training, overcrowded access to teaching platforms, lack of interaction, lack of efficient real-time evaluation and fatigue were current difficulties. Conclusions Good results of massive distance online education and teachers and students’ satisfaction with teaching platform performance show that online education can be used as a main means to replace traditional classroom education in emergency situations.