10 research outputs found
Effect of reducing 3.2% dietary protein level on the growth performance and immunity of Nile tilapia (Oreochromis niloticus) with supplementation of multi amino acids
Reducing dietary protein content in fish feeds will reduce cost of production if growth performance can be maintained. In this study, we assessed the effects of reduced dietary protein content from 33.5% to 27.4% with ideal amino acids profile on the growth, immune parameters, intestinal microvilli length and total ammonia nitrogen discharge of tilapia. After 8 weeks of feeding, growth performance and feed efficiency were not affected by reducing dietary protein content from 33.5% to 30.3%, while fish fed 27.4% CP had the lowest weight gain. Total ammonia nitrogen discharged into the water 9 hours after the feeding was decreased by about 35%. Serum lysozyme activity, blood respiratory burst activity and serum ACH50 were not significantly affected by dietary protein content. Fold height, enterocyte height and microvillus height of proximal and middle intestine were significantly increased with reducing of dietary protein. Results indicated that 3.2% dietary protein content can be reduced, which had no effects on growth performance and immunity of Nile tilapia in practical diet
Outbreak of COVID-19 and SARS in mainland China: a comparative study based on national surveillance data
Objective To compare the epidemiological characteristics
and transmission dynamics in relation to interventions
against the COVID-19 and severe acute respiratory
syndrome (SARS) outbreak in mainland China.
Design Comparative study based on a unique data set of
COVID-19 and SARS.
Setting Outbreak in mainland China.
Participants The final database included 82 858
confirmed cases of COVID-19 and 5327 cases of SARS.
Methods We brought together all existing data sources
and integrated them into a comprehensive data set.
Individual information on age, sex, occupation, residence
location, date of illness onset, date of diagnosis and
clinical outcome was extracted. Control measures
deployed in mainland China were collected. We
compared the epidemiological and spatial characteristics
of COVID-19 and SARS. We estimated the effective
reproduction number to explore differences in transmission
dynamics and intervention effects.
Results Compared with SARS, COVID-19 affected more
extensive areas (1668 vs 230 counties) within a shorter
time (101 vs 193 days) and had higher attack rate (61.8 vs
4.0 per million persons). The COVID-19 outbreak had only
one epidemic peak and one epicentre (Hubei Province),
while the SARS outbreak resulted in two peaks and two
epicentres (Guangdong Province and Beijing). SARSCoV-2 was more likely to infect older people (median
age of 52 years), while SARS-CoV tended to infect young
adults (median age of 34 years). The case fatality rate
(CFR) of either disease increased with age, but the CFR of
COVID-19 was significantly lower than that of SARS (5.6%
vs 6.4%). The trajectory of effective reproduction number
dynamically changed in relation to interventions, which
fell below 1 within 2 months for COVID-19 and within 5.5
months for SARS.
Conclusions China has taken more prompt and effective
responses to combat COVID-19 by learning lessons from
SARS, providing us with some epidemiological clues to
control the ongoing COVID-19 pandemic worldwid