The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation （6.0% BW/d） were used. Ap...The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation （6.0% BW/d） were used. Apparent digestibility （AD） of dry matter （DMAD）, protein （PAD） and protein real digestibility （PRD） were significantly affected by ration level, but not by feeding frequency when the ration level was similar. However, the feeding frequency affected the AD, DMAD, PAD and PRD significantly when the turtles were fed to satiation. The relationship between fecal protein content （Y） and protein intake （At） can be expressed as a quadric equation： Y=-0.1742＋0.1476X-0.0003X^2 （r^2=0.876, n=27, F=93.92, P〈0.01）.展开更多
Feeding frequency represents a potential strategy to improve the utilization of protein sources by fish.This study investigated its impact on the utilization of protein blend in gibel carp.The dietary fishmeal was tot...Feeding frequency represents a potential strategy to improve the utilization of protein sources by fish.This study investigated its impact on the utilization of protein blend in gibel carp.The dietary fishmeal was totally substituted with three protein blends consisting of Tenebrio molitor meal,Chlorella meal,Clostridium autoethanogenum protein,cottonseed protein concentrate,at ratios of 1:1:8:2,1:1:6:4,and 1:1:4:6,respectively.During an 8-week feeding trial,a total of 960 healthy fish(18.10 g)were randomly assigned to eight groups,each with three replicates.Then they were fed either twice daily(two meals per day)or four times daily(four meals per day)with four different diets.Higher feeding frequency increased feed intake and intestinal trypsin activity(P<0.05),and up-regulated the expression levels of genes related to amino acid or peptide transporter(pept1,ytlat2)and sensory receptors(casr,gprc6a,mglur4)in intestine(P<0.05).Moreover,it accelerated muscle protein turnover by increasing free amino acid content,aspartate aminotransferase activity and akt1 transcript levels(P<0.05),ultimately promoting growth.However,higher feeding frequency reduced protein apparent digestibility and feed efficiency(P<0.05).Dietary blended proteins elevated trypsin and chymotrypsin activities(P<0.01).Notably,the adverse effects observed with blended proteins(ratio at 1:1:8:2)on total essential amino acid digestibility and muscle protein metabolism-related gene expression were mitigated with increased feeding frequency,thus alleviating growth inhibition.Furthermore,the blended proteins at a ratio of 1:1:6:4 increased protein apparent digestibility(P<0.05),down-regulated mstn expression level(P<0.05),and up-regulated expression levels of genes related to protein synthesis(akt1,mtor,s6k1,eif4b,eif4e;P<0.05);thereby promoting protein utilization and muscle growth at four meals per day.Overall,feeding frequency interacted synergistically with blended proteins to influence growth and protein utilization in gibel carp,and a protein blend with a ratio of 1:1:6:4 was a superior alternative to fishmeal at both feeding frequencies.Future strategies aimed at replacing dietary fishmeal should consider the role of feeding frequency as a critical factor.展开更多
Gene expression and the content of hormones regulating feed intake and digestion are crucial for understanding gastric evacuation(GE)and feeding frequency in fish.This study assessed the effects of temperature and siz...Gene expression and the content of hormones regulating feed intake and digestion are crucial for understanding gastric evacuation(GE)and feeding frequency in fish.This study assessed the effects of temperature and size on these parameters by examining the domestication of steelhead trout(Oncorhynchus mykiss)at four temperatures(8℃,12℃,16℃,and 20℃)and with two sizes(75.99 g±10.48 g and 140.21 g±22.08 g)over two weeks.The trout were fasted for 72 h before the GE trial to ensure complete gastric emptying.In each GE trial,the expressions of peptide tyrosine(PYY),cholecystokinin(CCK),and ghrelin genes,along with corresponding serum hormone levels,were measured before feeding and at 0 h and 24 h after feeding,in conjunction with feed intake and 24-h gastric content mass.Results revealed significant effects of temperature on the expression of the three gastric genes.CCK expression increased at 8℃,correlating with reduced feed intake,while PYY and CCK increased at 20℃,correlating with accelerated gastric evacuation.Size significantly influenced serum levels of all three hormones,but the interaction between temperature and size did not affect PYY and ghrelin expression or their serum contents.This study provides molecular insights into how temperature and size regulate the digestion of steelhead trout,offering a theoretical framework for optimizing feeding frequency in aquaculture practices.展开更多
Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different...Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.展开更多
Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating ...Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating the impacts of urbanization on avian life-history traits are conducted in Europe and North America,while such studies are often lacking in quickly developing countries in Asia(e.g.,China).In this study,we examined the variations in reproductive life-history traits of Chinese Bulbuls(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 234 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.We collected data on seven life-history traits(laying date,incubation period,nestling period,clutch size,egg volume,hatching success rate,and fledging success rate).We used infrared cameras to record the number of feedings per hour as the measure of food resources for the nestlings.We measured nest predation pressure by monitoring 148 natural breeding nests during breeding seasons and 54 artificial nests immediately after breeding seasons.We then calculated the urbanization synthetic index(USI)as a measure of the level of urbanization and examined its relationship with the seven life-history traits.We found that Chinese Bulbuls laid eggs significantly earlier with increasing USI.However,the other six life-history traits did not vary significantly with the USI.Moreover,the feeding frequency of chicks increased significantly with the USI,but the nest predation pressure of Chinese Bulbuls decreased significantly with the USI.Increased food resources and reduced nest predation pressure in cities may lead to earlier laying date of Chinese Bulbuls.Further study should test whether the earlier laying date of Chinese Bulbuls is the result of phenotypic plasticity or genetic change.展开更多
基金Project supported by the Scientific and Research Bureau of Shenzhen, China
文摘The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation （6.0% BW/d） were used. Apparent digestibility （AD） of dry matter （DMAD）, protein （PAD） and protein real digestibility （PRD） were significantly affected by ration level, but not by feeding frequency when the ration level was similar. However, the feeding frequency affected the AD, DMAD, PAD and PRD significantly when the turtles were fed to satiation. The relationship between fecal protein content （Y） and protein intake （At） can be expressed as a quadric equation： Y=-0.1742＋0.1476X-0.0003X^2 （r^2=0.876, n=27, F=93.92, P〈0.01）.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA24010206)the earmarked fund for China Agriculture Research System (CARS45-09)
文摘Feeding frequency represents a potential strategy to improve the utilization of protein sources by fish.This study investigated its impact on the utilization of protein blend in gibel carp.The dietary fishmeal was totally substituted with three protein blends consisting of Tenebrio molitor meal,Chlorella meal,Clostridium autoethanogenum protein,cottonseed protein concentrate,at ratios of 1:1:8:2,1:1:6:4,and 1:1:4:6,respectively.During an 8-week feeding trial,a total of 960 healthy fish(18.10 g)were randomly assigned to eight groups,each with three replicates.Then they were fed either twice daily(two meals per day)or four times daily(four meals per day)with four different diets.Higher feeding frequency increased feed intake and intestinal trypsin activity(P<0.05),and up-regulated the expression levels of genes related to amino acid or peptide transporter(pept1,ytlat2)and sensory receptors(casr,gprc6a,mglur4)in intestine(P<0.05).Moreover,it accelerated muscle protein turnover by increasing free amino acid content,aspartate aminotransferase activity and akt1 transcript levels(P<0.05),ultimately promoting growth.However,higher feeding frequency reduced protein apparent digestibility and feed efficiency(P<0.05).Dietary blended proteins elevated trypsin and chymotrypsin activities(P<0.01).Notably,the adverse effects observed with blended proteins(ratio at 1:1:8:2)on total essential amino acid digestibility and muscle protein metabolism-related gene expression were mitigated with increased feeding frequency,thus alleviating growth inhibition.Furthermore,the blended proteins at a ratio of 1:1:6:4 increased protein apparent digestibility(P<0.05),down-regulated mstn expression level(P<0.05),and up-regulated expression levels of genes related to protein synthesis(akt1,mtor,s6k1,eif4b,eif4e;P<0.05);thereby promoting protein utilization and muscle growth at four meals per day.Overall,feeding frequency interacted synergistically with blended proteins to influence growth and protein utilization in gibel carp,and a protein blend with a ratio of 1:1:6:4 was a superior alternative to fishmeal at both feeding frequencies.Future strategies aimed at replacing dietary fishmeal should consider the role of feeding frequency as a critical factor.
基金National Key Research and Development Program of China(Nos.2024YFD2400300 and 2019YFD0901000)the Natural National Science Foundation of China(No.32373104).
文摘Gene expression and the content of hormones regulating feed intake and digestion are crucial for understanding gastric evacuation(GE)and feeding frequency in fish.This study assessed the effects of temperature and size on these parameters by examining the domestication of steelhead trout(Oncorhynchus mykiss)at four temperatures(8℃,12℃,16℃,and 20℃)and with two sizes(75.99 g±10.48 g and 140.21 g±22.08 g)over two weeks.The trout were fasted for 72 h before the GE trial to ensure complete gastric emptying.In each GE trial,the expressions of peptide tyrosine(PYY),cholecystokinin(CCK),and ghrelin genes,along with corresponding serum hormone levels,were measured before feeding and at 0 h and 24 h after feeding,in conjunction with feed intake and 24-h gastric content mass.Results revealed significant effects of temperature on the expression of the three gastric genes.CCK expression increased at 8℃,correlating with reduced feed intake,while PYY and CCK increased at 20℃,correlating with accelerated gastric evacuation.Size significantly influenced serum levels of all three hormones,but the interaction between temperature and size did not affect PYY and ghrelin expression or their serum contents.This study provides molecular insights into how temperature and size regulate the digestion of steelhead trout,offering a theoretical framework for optimizing feeding frequency in aquaculture practices.
基金Supported by Key R&D Program of Hubei Province(2022BBA0058)。
文摘Three experimental groups with different feeding frequencies,different feeding rates and compensatory feeding were set up to study their effects on the growth of Micropterus salmoides.The results showed that different feeding rates of 2%,3%and 4%had no significant effects on the growth of M.salmoides.Therefore,before the individual weight of 50 g,the fish could be fed with a feeding rate of 4%,which could be gradually decreased to 2%in the later period.Under the condition of relatively fixed feeding rate,different feeding frequencies had an impact on the growth of M.salmoides.Under the conditions of suitable water temperature,it is reasonable to feed twice daily.The experimental fish fed for 5 d and then deprived of feed for 1 d showed fully compensatory growth,and there were no significant differences in weight gain rate,daily weight gain and specific growth rate compared with the continuous feeding group(P>0.05).Therefore,according to the feeding conditions of fish in the breeding process,stopping feeding for 1 d every 5 d could save feed and labor and improve breeding efficiency.
基金supported by the National Natural Science Foundation of China(32271743,31971545,31071908)。
文摘Urbanization brings new selection pressures to wildlife living in cities,and changes in the life-history traits of urban species can reflect their responses to such pressures.To date,most of the studies investigating the impacts of urbanization on avian life-history traits are conducted in Europe and North America,while such studies are often lacking in quickly developing countries in Asia(e.g.,China).In this study,we examined the variations in reproductive life-history traits of Chinese Bulbuls(Pycnonotus sinensis)along the urbanization gradient in Hangzhou,China.We detected 234 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013.We collected data on seven life-history traits(laying date,incubation period,nestling period,clutch size,egg volume,hatching success rate,and fledging success rate).We used infrared cameras to record the number of feedings per hour as the measure of food resources for the nestlings.We measured nest predation pressure by monitoring 148 natural breeding nests during breeding seasons and 54 artificial nests immediately after breeding seasons.We then calculated the urbanization synthetic index(USI)as a measure of the level of urbanization and examined its relationship with the seven life-history traits.We found that Chinese Bulbuls laid eggs significantly earlier with increasing USI.However,the other six life-history traits did not vary significantly with the USI.Moreover,the feeding frequency of chicks increased significantly with the USI,but the nest predation pressure of Chinese Bulbuls decreased significantly with the USI.Increased food resources and reduced nest predation pressure in cities may lead to earlier laying date of Chinese Bulbuls.Further study should test whether the earlier laying date of Chinese Bulbuls is the result of phenotypic plasticity or genetic change.
