• ALGAE
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• 제29권2호
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• pp.137-152
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• 2014

Mixotrophic protists play diverse roles in marine food webs as predators and prey. Thus, exploring mixotrophy in phototrophic protists has emerged as a critical step in understanding marine food webs and cycling of materials in marine ecosystem. To investigate the feeding of newly described mixotrophic dinoflagellate Ansanella granifera, we explored the feeding mechanism and the different types of species that A. granifera was able to feed on. In addition, we measured the growth and ingestion rates of A. granifera feeding on the prasinophyte Pyramimonas sp., the only algal prey, as a function of prey concentration. A. granifera was able to feed on heterotrophic bacteria and the cyanobacterium Synechococcus sp. However, among the 12 species of algal prey offered, A. granifera ingested only Pyramimonas sp. A. granifera ingested the algal prey cell by engulfment. With increasing mean prey concentration, the growth rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but became saturated at a concentration of $434ngCmL^{-1}$ (10,845 cells $mL^{-1}$). The maximum specific growth rate (i.e., mixotrophic growth) of A. granifera feeding on Pyramimonas sp. was $1.426d^{-1}$, at $20^{\circ}C$ under a 14 : 10 h light-dark cycle of $20{\mu}Em^{-2}s^{-1}$, while the growth rate (i.e., phototrophic growth) under similar light conditions without added prey was $0.391d^{-1}$. With increasing mean prey concentration, the ingestion rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but slightly at the concentrations ${\geq}306ngCmL^{-1}$ (7,649 cells $mL^{-1}$). The maximum ingestion rate of A. granifera feeding on Pyramimonas sp. was 0.97 ng C $predator^{-1}d^{-1}$ (24.3 cells $grazer^{-1}d^{-1}$). The calculated grazing coefficients for A. granifera feeding on co-occurring Pyramimonas sp. were up to $2.78d^{-1}$. The results of the present study suggest that A. granifera can sometimes have a considerable grazing impact on the population of Pyramimonas spp.

• 한국축산식품학회지
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• 제42권4호
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• pp.609-624
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• 2022

Tenebrio molitor larvae, as known as edible insects, has advantages of being rich in protein, and has been recognized as a suitable alternate protein source for broiler and pig feed. Moreover, given their ability to biodegrade polystyrene, a major pollutant, Tenebrio molitor larvae has been proposed as an innovative solution to environmental problems. In the present study, we investigated the toxicity of Tenebrio molitor larvae powder (TMlp) ingested with expanded-polystyrene (W/ eps) through in vitro and in vivo experiments. The objective of this study was to determine whether TMlp W/ eps can be applied as livestock alternative protein source. For in vitro experiments, cytotoxicity test was performed to investigate the effects of TMlp-extract on the viability of estrogen-dependent MCF-7 cells. The possibility of estrogen response was investigated in two groups: Expanded-polystyrene-fed (W/ eps) TMlp group and without expanded-polystyrene-fed (W/o eps) TMlp group. For in vivo experiments, The male Sprague-Dawley rats were divided based on the dosage of TMlp administered and oral administration was performed to every day for 5 weeks. A toxicological assessments were performed, which included clinical signs, food consumption, body and organ weights, hematology, serum chemistry, and hematoxylin and eosin staining of liver and kidney. There were no specific adverse effect of TMlp W/ eps-related findings under the experimental conditions of this study, but further studies on both sexes and animal species differences should be investigated. In conclusion, TMlp W/ eps was considered non-toxic and observed to be applicable as an alternative protein source for livestock feed.

• 농업과학연구
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• 제50권4호
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• pp.603-616
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• 2023

This study was conducted to investigate the productivity, meat quality, blood variables, stress responses, and litter quality of broilers offered feed with different levels of Glycine (Gly) supplementation under heat stress condition. A total of 760 one-day-old Ross 308 broiler males were randomly assigned to one of the four dietary treatment groups: (1) basal diet (control; CON); (2) basal diet + Gly 0.1% (Gly 0.1%); (3) basal diet + Gly 0.2% (Gly 0.2%); and (4) basal diet + Gly 0.3% (Gly 0.3%). The environments for all the treatments groups were maintained according to broiler rearing guidelines from day 1 to day 21, and heat stress condition (32 ± 1℃, 60 ±5%) was created from day 22 to the end. The addition of Gly increased weight gain and affected feed intake (p < 0.05). Gly 0.1% group had higher pH and ferric reducing antioxidant power (FRAP) in the chicken meat and lower heterophil (HE)/lymphocyte (LY) ratio in the blood (p < 0.05). In particular, Gly 0.2% treatment group had lower serum corticosterone level (p < 0.05) than other groups. For jejunum morphology, the addition of Gly 0.2% significantly reduced the depth of the crypts (p < 0.05). However, the addition of Gly did not significantly affect litter quality (p > 0.05). In conclusion, the addition of glycine improved productivity and meat quality, alleviated heat stress, and improved intestinal function. Further studies are needed to determine the optimal level and mechanism of action of the additive when ingested.

• Asian-Australasian Journal of Animal Sciences
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• 제2권4호
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• pp.579-582
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• 1989

Previous experiments have shown that aqueous sodium silicate ingested in drinking water may modify the gastrointestinal uptake and(or) tissue retention of certain trace elements, including heavy metals. The present experiment tested, with a mineral balance trial using sheep, the hypothesis that dietary silicic acid could modify uptake, retention and(or) biological effects of dietary Cd. Twenty-four wethers were fed a fibrous diet of ground alfalfa hay and cottonseed hulls to which either 0 or 150 ppm Cd was added as $CdCl_2$ and 0, .5 or 1% silicic acid (as dry matter of the diet). Body weight, feed intake, excretion of urine (volume) and feces (weight), digestibility of dry and organic matter, retention of nitrogen, and packed cell volumes of blood were not affected by either Cd or silicic acid (P<.10). Cadmium decreased (P<.05) Ca retention and increased (P<.01) Mg retention. Silicic acid decreased (P<.05) K retention. Silicic acid failed (P<.01) to modify the retention of added dietary Cd. Body retention of K, Mn and Ni in response to silicic acid varied with Cd levels. If Cd is interfering with mineral retention, silicic acid may be effective in preventing this interference.

• Asian-Australasian Journal of Animal Sciences
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• 제5권4호
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• pp.699-707
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• 1992

Three goats were fed with $^{15}N$-labelled rice straw to study the characteristics of digestion, assimilation, metabolism and excretion of C and N compounds from rice straw. It was shown that the amount of $^{15}N$ assimilated into the bodies of the two slaughtered goats accounted for 38.5 and 23.6% of the total amount of $^{15}N$ ingestion in the experimental diet by each goat. The $^{15}N$ excreted via the feces and urine for the three goats accounted for 34.8, 33.2 and 33.9% of the total amount of $^{15}N$ ingested in the feed of the 3 goats. The recoveries of $^{15}N$ from the two slaughtered goats were 73.3 and 57.5%, with the corresponding rates of $^{15}N$ loss 26.7 and 42.5% respectively. The amino acids digestibilities were 68.7 and 54.0%, while the digestibilities of carbohydrates were 74.8 and 67.7% respectively for goats 1 and 3.

• 식물병연구
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• 제15권3호
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• pp.262-265
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• 2009

PDA 배지상에서 작은뿌리파리 유충과 성충은 토양 전염성 병원균인 Fusarium oxysporum을 전반하였으며, 성충에 비해 유충의 전반이 높았다. 작은뿌리파리 유충은 F. oxysporum 균을 섭식하여 전반하였으며, 성충은 몸체에 균을 묻혀 전반하였다. 형광발현 형질전환 F. oxysporum 균을 제작하여 작은뿌리파리 유충에 먹인 결과 균은 소화관을 따라 분포하였다.

• 한국양식학회지
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• 제21권3호
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• pp.184-189
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• 2008

흰다리새우 Litopenaeus vannamei 적정 사육기법을 개발하고자 사육수온(20, 23과 $26^{\circ}C$)에 따른 간췌장, 전장과 중장에서의 trypsin 활성 및 먹이섭취량을 조사하였다. $26^{\circ}C$에서의 흰다리새우 간췌장내의 효소활성은 $23^{\circ}C$ 구간보다 2배, $20^{\circ}C$ 구간보다 3배의 활성을 보였다. 전장에서의 효소활성은 사육수온에 관계없이 300 nmol/mg/min 과 340 nmol/mg/min로 유사한 최대 활성을 보였으나 먹이섭취 후 최대 활성이 나타나는 시간은 수온이 높을수록 짧아지는 것으로 나타났다. 중장에서의 효소활성은 먹이섭취량과 관계없이 $26^{\circ}C$ 구간에서 가장 높게 기록되어 수온이 높을수록 중장에서의 효소활성 또한 높아지는 것으로 나타났다. 체중에 대한 전장과 중장의 무게 비율의 변화, 즉 섭취된 먹이량에 의한 비율변화를 조사한 결과 전장에서의 최대 먹이섭취는 $23^{\circ}C$ 구간으로 체중의 0.6%를 섭취하였으며, $26^{\circ}C$는 0.5% 그리고 $20^{\circ}C$에서는 0.4%의 먹이를 섭취한 것으로 나타났다. 본 연구에서 최대먹이섭취는 $23^{\circ}C$에서 일어났지만 수온이 높은 구간인 $26^{\circ}C$에서 효소의 활성은 가장 높았고 배설률 또한 높아서 먹이의 잔류시간이 가장 짧은 것으로 나타났다. $20^{\circ}C$ 구간에서는 가장 적은 양의 먹이를 섭취하였고 효소활성 또한 가장 낮았으나 소화관내 먹이 잔류율이 실험기간 동안 가장 높은 것으로 나타났다. 각 수온에서 먹이섭취량에 따른 소화효소의 활성변화와 배설률에 따른 먹이 잔류시간을 고려하여 먹이공급량과 시간을 조절한다면 최적의 성장을 유도할 수 있는 방법으로 제시될 수 있다는 가능성을 확인하였다.

• 한국토양동물학회지
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• 제5권2호
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• pp.125-131
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• 2000

본 연구는 상수원 보호구역 내의 젖소 사육농가에서 발생하는 과잉의 분뇨를 지렁이 먹이로 사용하여 환경친화적 처리방법을 모색하기 위하여 수행하였다. 그 일환으로 지렁이 양식사를 고안하였으며 이 양식시설을 이용하여 지렁이가 우분을 가장 잘 먹을 수 있는 환경을 조사하였다. 또한 이러한 방법에 의해 증식된 지렁이를 닭 먹이로 활용하기 위한 가능성을 탐색하였으며, 지렁이 배설물(분변토)의 특성에 관하여 연구를 수행한 결과, \circled1 지렁이양식 하우스의 겨울철 사육상 기온은 밤과 낮의 기온 차이가 거의 없이 영상의 기온을 유지하였고,여름철에는 낮과 밤 모두 25-28$^{\circ}C$사이로 유지되었다. \circled2 지렁이 양식상의 피복 방법에 따른 우분 소비량은 무피복보다는 밀착피복이 많았고, 간격피복이 파장 많았다. \circled3 우분은 배설후 경과일수가 적고 순수한 우분일 때 섭식량이 많았다. 양식상에서 지렁이의 탈출수는 우분의 경과일수와 상관없이 밀착피복에서 가장 많았고, 간격피복에서는 우분의 경과 일수가 많을수록 탈출수가 많이 나타났다. \circled5 지렁이 치사는 밀착피복에서만 나타났다. \circled6 지렁이의 우분처리 능력은 우분과 분변토의 건물중량 기준으로 51%가 감량되었고, 무기염류는 우분에 대하여 N: 41%, P$_2$ $O_{5}$: 50%, $K_2$O: 60%가 각각 절대량이 감소되었다. \circled7 생체 지렁이를 닭의 사료로 첨가하려면 닭의 체중 600g 이상에서는 가능하나, 450 g 미만인 경우는 닭이 죽는 경우가 있었다. 따라서 상수원 보호구역 내치 소규모 젖소 사육농가에서 발생하는 과잉의 분뇨를 지령이 양식하우스를 설치하여 먹이로 활용하여 처리할 수 있다고 판단된다. 또한 처리 후 동시에 우분을 그 양의 반이상이 감량되면서 퇴비(분변토)로 전환되는 비법이 있을 뿐만 아니라 부영양화 물질을 줄여 수길 오염을 경감하는 효과를 기대 할 수 있을 것이다.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1158-1161
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• 2004

This study chiefly aims to ascertain the effect of birth weight and litter size on productive performance in rabbits. After delivery kits were removed from their mothers for individual weighing and randomly assigned to one of the following three experimental treatments: Group (KT 6) with six tiny kits (about 45 g) per litter (21 litters); Group (KT 8) with eight tiny kits (about 45 g) per litter (17 litters); Group (KN8) with eight normal kits (about 70 g) per litter (20 litters). The litters, separated from their mothers by putting them in a closed cage, suckled one time a day for 15 minutes. Daily milk production was measured by weighing the does immediately before and after suckling; body weight of kits was measured on a weekly basis. At weaning 60 rabbits per group were raised for six weeks to ascertain post-weaning performance and health. Compared with the two other groups, the kits of group KT8 ingested smaller quantities of milk both during the first 3 weeks (497.7 vs. 520.0 vs. 544.3 g, respectively for groups KT8, KN8, KT6) and the following period (261.3 vs. 285.0 vs. 302.7 g, respectively for KT8, KN8, KT6). The differences between groups KT8 and KT6 were statistically significant (p<0.01) in the first period while in the second period also KN8 group showed milk intake different in respect of KT8 (p<0.01) and KT6 (p<0.05) groups. Solid feed intake was significantly (p<0.05) lower in group KT6 (23.1 vs. 26.2 vs. 26.8 g/d, respectively for groups KT6, KN8, KT8). At weaning the kits of group KN8 always weighed more (966 vs. 894 vs. 888 g; p<0.01, respectively for groups KN8, KT6, KT8). After weaning, no parameter considered (daily weight gain, feed intake, feed conversion ratio, mortality and risk sanitary index) was affected by birth weight and litter size.

• 한국어류학회지
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• 제21권4호
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• pp.253-261
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• 2009

만경강에 서식하는 참종개와 점줄종개의 서식환경과 섭식생태를 2005년부터 2006년까지 조사하였다. 참종개와 점줄종개는 중 상류지역에 혼서하고 있었으나 미소서식지에서 참종개는 유속이 비교적 빠르고 수심 30~60 cm의 돌이 쌓인 곳에서, 점줄종개는 유속이 느리고 수심이 30~100 cm의 모래지역에서 서식하여 차이를 보였다. 두 종은 모두 주행성 어류로 3월부터 10월까지 활동기로, 11월부터 2월까지는 월동기로 나타났으며, 월동기간동안 참종개는 자갈과 돌이 쌓인 곳에, 점줄종개는 모래가 쌓인 곳에 파고 들어가 은신하였다. 참종개는 깔다구류와 수서곤충을 주로 섭식하였으며, 점줄종개는 깔다구류와 요각류, 물벼룩류를 주로 섭식하였고, 섭식률은 두 종 모두 4월과 9월에 높게 나타났으나 겨울동안은 섭식하지 않았다.