We investigated the effects of low temperature(8.5℃) on the growth and feeding rates and feed conversion efficiency of juvenile P.olivaceus with an average initial weight of 3.87 ± 0.06 g(mean ± SE).Fish we...We investigated the effects of low temperature(8.5℃) on the growth and feeding rates and feed conversion efficiency of juvenile P.olivaceus with an average initial weight of 3.87 ± 0.06 g(mean ± SE).Fish were exposed to 8.5℃ for 0(control),1,2,3 and 4 weeks,and then to 20℃ for 10,9,8,7 and 6 weeks,respectively.Low temperature clearly led to growth depression.The weight of fish exposed to low temperature for 1 week was restored to that of control,while that of fish exposed to low temperature longer was significantly decreased(P < 0.05).During the entire low-temperature period,specific growth rate,feeding rate and feed conversion efficiency of the fish were significantly lower(P < 0.05) than those of control,while in the whole recovery period,specific growth and average feeding rate were markedly higher(P < 0.05) than those of control.At the end of experiment,only the feeding rate of the fish exposed to low temperature for 1 week was not significantly different from that of control(P > 0.05).Feeding rate and feed conversion efficiency were reduced at low temperature in juvenile P.olivaceus.The compensatory growth of juvenile P.olivaceus may therefore be attributed to the improvement of feeding rate.Our results suggested that growth depression occurs when juvenile P.olivaceus are exposed to low temperature for more than one week.展开更多
文摘目的·了解新冠疫情大流行期间儿童及青少年的新发焦虑症状,分析影响该症状的相关因素。方法·依托成都儿童正向成长(Chengdu Positive Child Development,CPCD)队列,纳入成都市5所中小学的儿童和青少年共5566例,分别建立儿童和青少年新发焦虑症状纵向研究队列并开展2轮调查。第一轮调查(基线调查)的时间为2019年12月—2020年1月,通过促进儿童青少年正面成长研究学生调查问卷收集队列成员的一般人口学特征信息;第二轮调查(随访调查)的时间为2020年2—7月,补充收集队列成员的新冠病毒感染史,以及饮食、学习、社交和娱乐活动是否受到新冠疫情的影响等信息。利用儿童焦虑性情绪障碍筛查表(Screen for Child Anxiety Related Emotional Disorders,SCARED)评估所有研究对象的新发焦虑症状。采用多因素Logistic回归模型对儿童和青少年新发焦虑症状的影响因素进行分析。结果·SCARED评估结果显示,在新冠疫情大流行期间成都儿童及青少年新发焦虑症状的发病率为13.47%;其中儿童新发焦虑症状纵向研究队列中的发病率为11.91%,青少年新发焦虑症状纵向研究队列中的发病率为14.25%。χ^(2)检验的结果显示,儿童新发焦虑症状的发病率在年龄、本人或家人是否感染新冠病毒,以及饮食、学习和社交活动是否受到影响间的差异具有统计学意义(均P<0.05);青少年新发焦虑症状的发病率在性别、年级、年龄、居住地区,以及饮食、学习、社交和娱乐活动是否受到影响间差异亦具有统计学意义(均P<0.05)。多因素Logistic回归分析的结果显示:对儿童来说,6~8岁是其新发焦虑症状的保护因素,而本人或家人感染过新冠病毒、学习活动受到影响是其危险因素(均P<0.05);对青少年来说,男性、居住在城镇、年级≤6是其新发焦虑症状的保护因素,而学习活动受到影响是其危险因素(均P<0.05)。结论·对于儿童和青少年来说,在新冠大流行期间影响其新发焦虑症状的因素并不完全一致;对于儿童来说,年龄、本人或家人是否感染新冠病毒、学习是否受到影响是其新发焦虑症状的独立影响因素,但对青少年来说则是性别、年级、居住地区和学习是否受到影响。因此,在动态关注儿童和青少年心理健康状态、持续做好心理健康干预工作过程中,应遵循成长规律,充分考虑儿童和青少年的发展特点,采取不同的策略和措施。
基金financially supported by the National Natural Science Foundation of China(No.30600462)
文摘We investigated the effects of low temperature(8.5℃) on the growth and feeding rates and feed conversion efficiency of juvenile P.olivaceus with an average initial weight of 3.87 ± 0.06 g(mean ± SE).Fish were exposed to 8.5℃ for 0(control),1,2,3 and 4 weeks,and then to 20℃ for 10,9,8,7 and 6 weeks,respectively.Low temperature clearly led to growth depression.The weight of fish exposed to low temperature for 1 week was restored to that of control,while that of fish exposed to low temperature longer was significantly decreased(P < 0.05).During the entire low-temperature period,specific growth rate,feeding rate and feed conversion efficiency of the fish were significantly lower(P < 0.05) than those of control,while in the whole recovery period,specific growth and average feeding rate were markedly higher(P < 0.05) than those of control.At the end of experiment,only the feeding rate of the fish exposed to low temperature for 1 week was not significantly different from that of control(P > 0.05).Feeding rate and feed conversion efficiency were reduced at low temperature in juvenile P.olivaceus.The compensatory growth of juvenile P.olivaceus may therefore be attributed to the improvement of feeding rate.Our results suggested that growth depression occurs when juvenile P.olivaceus are exposed to low temperature for more than one week.
