• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.232-237
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• 2001

This study was conducted to clarify the effects of physical stimulation to the rice plant by free-ranging ducks (Chinese native ducks) on growth, lodging resistance and yield of the rice plants in a rice-duck farming system. Two paddy fields were used for this experiment, one exposed to physical stimulation (PS) and the other with no physical stimulation (NPS). Fifteen days after ducks were introduced into the paddy plot, rice plants in the PS field were significantly (P<0.05) shorter than those in the NPS field. Measurements of lodging characteristics showed that, the 3rd internode was significantly (P<0.05) shorter in the PS treatment than in the NPS treatment, but neither the 4th internode length nor the center of gravity of the rice plants differed between treatments. The breaking strength of $N_4$ in PS rice was significantly (P<0.05) higher than in NPS rice, however the bending moment and the lodging index of $N_3$ (distance between fulcra - 5 cm) was significantly (P<0.05) lower in PS than in NPS. The number of panicles per $m^2$ was significantly (P<0.05) greater in PS rice than in NPS, but there was no such difference in spikelet number per panicle, percentage of ripened grain or weight per 1000 kernels. Paddy rice yield per $m^2$ in the PS treatment was significantly (P<0.05) higher than that in the NPS treatment.

• Korean Journal of Poultry Science
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• v.46 no.4
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• pp.223-234
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• 2019

This study investigated the effects of thawing methods and storage time on the quality of frozen duck meat. Meat was obtained from eight-week-old Korean native ducks (average weight=2.8 kg). Seventy-two samples were divided into eight treatments (three replicates/treatment, three samples/replicate) with 2 × 4 factorial arrangement based on two thawing methods (under running water at 12℃ for 3 h and in a refrigerator at 5℃ for 24 h) and four storage times (1, 3, 6, and 12 months). CIE b^* was significantly different among different storage time treatments, reaching its lowest after 6 months (P<0.05). Cooking loss did not differ between storage times; however, it was significantly lower following application of the fast thawing treatment (P<0.05). Water-holding capacity of meat stored for one month was highest compared to that of meat stored for a longer period (P<0.05). Additionally, there were significant differences based on storage time in γ-linoleic acid (C18:3n6) and eicosenoic acid (C20:1n9) contents (P<0.01), as well as in protein contents (P<0.05). Palmitoleic acid (C16:1n7) typically decreased after three months of storage; however, this decline was not significant compared to other storage times. Essential amino acids contents, except methionine, were significantly difference at six and 12 months of storage (P<0.05). Similarly, non-essential amino acid contents, except tyrosine, were significantly different among storage periods (P<0.05, P<0.01). Alternatively, there were no significant differences in the chemical composition, fatty acid content, or amino acid content based on the thawing method.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.382-390
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• 2015

This work was conducted to investigate the performance and meat characteristics of commercial Korean native duck (KND). A total of 180 1-d-old ducklings of 2-way crossbreds from A and B lines (from National Institute of Animal Science) were used in this work and divided into 4 groups (3 replicates/group, 15 birds/replicate). The four groups were 4 crossbreds as AA (A line [♀]${\times}$A line [♂]), AB (A line [♀]${\times}$B line [♂]), BB (Pure line B strains) and BA (B strains [♀]${\times}$A strain [♂]). Ducks were fed diets based on corn-soybean meal for 0 to 3 wk (22.4% crude protein [CP], 2,945 kcal/kg metabolizable energy [ME]) and 3 to 8 wk (18.4% CP, 3,047 kcal/kg ME). As a result of this study, average body weight of 4 crossbreds were 625, 1,617, 2,466, and 2,836 g at 2, 4, 6, and 8 weeks, respectively, and significantly increased over the period of time (p<0.05). Body weight of BB group was greater than other crossbreds at the age of 6 weeks (p<0.05). There was a significant difference in weekly body weight gains (p<0.05), which were 573, 991, 850, and 371 g at 2, 4, 6, and 8 weeks old, respectively. Uniformity of 4 crossbreds was 84.9%, 80.5%, and 72.5% at 6, 7, and 8 weeks, respectively, and there was no difference among crossbreds. Body weight gain of BB crossbred was highest among crossbreds (p<0.05). Weekly feed intake significantly increased with weeks as 669, 1,839, 2,812, and 3,381 g at 2, 4, 6, and 8 weeks respectively (p<0.05). Feed intakes of AA and BB crossbreds were higher at 2 to 4 weeks old than others and that of BB crossbred was highest at 4 to 6 weeks old (p<0.05). Weekly feed conversion ratios were 1.17, 1.86, 3.32, and 9.37 at 0 to 2, 2 to 4, 4 to 6, and 6 to 8 weeks old, respectively, and it increased with age (p<0.05). There was no significant difference in feed conversion ratio among crossbreds. Carcass yields of 4 crossbreds were 73.6%, 71.6%, 73.5%, and 71.7%, respectively, so there was no significant difference among crossbreds. There was no difference in wing, neck, breast and leg ratios among crossbreds. However, back ratios of 4 crossbreds were 17.6%, 18.0%, 15.8%, and 17.6%, respectively, and back ratio of BB was the highest among crossbreds. Finally, these results may provide the basic data on the production, carcass quality, fatty acid and amino acid composition of commercial KND with 2-way crossbreeding.

• Korean Journal of Poultry Science
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• v.47 no.2
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• pp.61-68
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• 2020

This study was conducted to compare and analyze meat quality of Korean native duck (KND) meat relative to stocking density. The stocking densities under investigation were 4, 5, 6, 7, 8 and 9 birds/㎡. The experiment comprised six treatments and four replications, wherein the breast meat (pH, meat color, and physicochemical properties) and leg meat (fatty acid contents) of 8-week-old KNDs (2.8±0.2 kg) were used. pH of breast meat decreased linearly and quadratically (P<0.05) as stocking density increased. Ash content also decreased linearly (P<0.05) as stocking density increased; however, moisture, fat, and protein contents did not differ significantly among treatments. Furthermore, meat color and cooking loss (CL) increased linearly (P<0.05) as stocking density increased whereas neither shear force (SF) nor water holding capacity (WHC) displayed a significant difference among treatments. Palmitic acid (C16:0) and stearic acid (C18:0) contents decreased quadratically (P<0.05) as stocking density increased whereas, conversely, linoleic acid (C18:1n9) and eicosenoic acid (C20:1n9) contents increased linearly (P<0.05) as stocking density increased. Additionally, γ-linoleic acid (C18:3n6) content increased linearly and quadratically (P<0.05) as stocking density increased, but a decrease (P<0.05) was observed in arachidonic acid (C20:4n6) content. Saturated fatty acid (SFA) and total unsaturated fatty acid (TUFA) contents did not show significant differences among treatments relative to stocking density. However, monounsaturated fatty acid (MUFA) content increased linearly (P<0.05) and polyunsaturated fatty acid (PUFA) content decreased linearly (P<0.05) as stocking density increased. These results can be utilized as basic data for research on the effect of stocking density on KNDs.

• Korean Journal of Poultry Science
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• v.39 no.1
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• pp.45-52
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• 2012

This study was carried out to investigate the growth performance and the carcass ratio of meat-type Korean Native Ducks. Four hundred twenty Korean Native Ducks' chicks were selected and divided into four treatments (7 replications/ treatment, 15 birds/replication) by strains (A and B) and gender(male and female) with $2{\times}2$ fractal factors. There was no significant difference between A and B on the body weight at 2, 4, 6, and 8 weeks old (P>0.05). However, body weight of female was higher at 2 weeks old than male while that of male was higher at the 8 weeks old (P<0.01). Daily feed intake of male was higher compared to female during 6~8 weeks (P<0.05). On weekly body weight gain, there was no significant difference between strains, but gained body weight of male was higher until 2 weeks old while that of female was higher during 6~8 weeks (P<0.01). On the live body weight and carcass weight by strains and genders, B strain was higher than A strains at the 8 weeks of age (P<0.01). Carcass yield was the highest at 8 weeks of age in both strains (P<0.05). These results may provided the basic data on growth performance and carcass ratio of meat-type Korean Native Ducks.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.35-42
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• 1970

Five samples of Korean native Maeju(fermented soy-bean mash) loaves which were collected each from Kyunggi, Chungchung, Kangwon, Cholla and Kyungsang-Do were examined for their fermenting microorganisms. The results of taxonomic and ecological studies of fermentation microorganisms in these Maeju loaves were as the fellows. (1) The fungus flora grew only is the outer layer of Maeju loaves. Miscellaneous molds, 3 species of Mucor, 2 species of Pericallium., one species each of Scopulariopsis and Aspergillus, were isolated. None of them seemed exclusively predominant to be able to designate as the ecologically significant. (2) The bacterial flora which consisted of two species, Bacillus subtilis and Bacillus pumilus were distributed uniformly in th a entire Maeju loaves. The inner parts of Maeju loaves were especially inhabited solely by these bacterial flora. Probably the Korean native Maeju fermentation could be characterized by these bacterial flora. A Staphylococcus species was also isolated probably as a casual contaminant. (3) The yeasts, Rhodotorula flava and Torulopsis dattila, were isolated from Maeju loaves though their ecological significance was not clear. (4) The ecological aspects of fermentation microbes in the outer and inner parts of Maeju loaves were apparently different, consequently different fermentation processes might have occurred in these two parts and it brought quite different final outlooks in the final matured Maeju loaves. The outer part, rather rigid and dry, retained the light brown color of boiled soy-bean; whereas the inner part, soft and sticky, showed dark brown color indicating severe chemical changes. (5) The aflatoxin producing mold, Aspergillus oryzae was isolated from one sample among 5 of Maeju loaves. In addition to the low probability of isolability from Maeju loaves samples, since this mold grew only in the outer layer of Maeju loaves with such a low population density, about $10^4/g$, perhaps the aflatoxin problem in Korean native soysauce may not be critical.

• Korean Journal of Poultry Science
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• v.39 no.3
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• pp.167-175
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• 2012

This study was undertaken to assess dietary CP and ME concentrations for optimum growth performance and carcass characteristics of Korean Native male ducks. In a $3{\times}3$ factorial arrangement, 1-d-old Korean Native male ducks were completely randomized design to experimental diets with 3,000, 2,900, and 2,800 kcal of ME/kg of diet; each contained 23, 22, and 21% CP, respectively, from 0 to 3 wk of age. From 4 to 8 wk of age, experimental diets had 3,100, 3,000, and 2,900 kcal of ME/kg of diet, and each contained 19, 18, and 17% CP, respectively. Each dietary treatment was replicated 4 times, and feed and water were provided ad libitum. Body weight, feed intake and uniformity were measured at 3 wk and 8 wk, and carcass characteristics were evaluated at 8 wk. As CP increased from 21 to 23 %, the body weight, BW gain and feed conversion ratios (FCR) linearly improved (P<0.01) during 0 to 3 wk of age. From 4 to 8 wk of age, the body weight, feed intake, BW gain, FCR and uniformity were not different (P>0.05). Carcass ratios of birds fed 3,000 kcal of ME/kg diets from 3 to 8 wk of age were quadratically increased significantly (P<0.01). As ME and CP increased, respectively, relative weight of liver weight per 100 g of BW was linearly decreased (P<0.01). Relative weights of left breast, thigh and drumstick weight per 100 of BW were not different (P>0.05). Also, breast meat color, pH, cooking loss and shear force were not different (P>0.05). Thus, diets with 2,800 kcal of ME/kg and 23% CP or with 2,900 kcal of ME/kg and 17% CP at 0 to 3 wk and 4 to 8 wk, respectively, were used more efficiently. However, diets with 3,000 kcal of ME/kg at 4 to 8 wk in carcass rate was quadratically increased.

• Korean Journal of Poultry Science
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• v.39 no.2
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• pp.143-149
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• 2012

This work was carried out to investigate the performance of growing period of large-type Korean native ducks. A total of four hundred twenty female and male duck chicks generated from A and B strains of ducks. Groups were four crossbreds (3 replications/crossbred, 35 birds/replication) as $2{\times}2$ factors (2 strains, A and B; 2 genders, female and male). On the body weight, male of B strains was the highest among 4 treatments after the age of 4 week (P<0.05). Body weight of B strain was higher than that of A strain at all period (P<0.05). Body weight of male was higher compared to that of female after the age of 4 week (P<0.05). On the body weight gain, male of B strain was the highest and female of A strain was the lowest among 4 treatments at 0~8, 0~12, 0~16 and 0~20 weeks (P<0.05). Body weight gain of male was higher than that of female after the age of 4 week (P<0.05). On the feed intake, male of B strain was the highest among 4 treatments from the age of 0 week and to the age of 4, 12, 16 and 20 week (P<0.05). Feed intake of male was higher than that of female at 0~12, 0~16 and 0~20 weeks (P<0.05). On the feed conversion ratio, male of B strain was the highest among other treatments 0~4 weeks and female of A strain was at 0~8 and 0~12 weeks (P<0.05). Feed intake of female was higher compared to that of female at 0~8 weeks and male was high at 0~20 weeks. These results provided the basic data on the record of growing phase of large-type Korean native ducks.

• Korean Journal of Poultry Science
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• v.40 no.3
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• pp.235-241
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• 2013

This work was carried to evaluate effect of different raising periods on fatty acids and amino acids properties of Korean native commercial ducks. Korean native ducks (n = 90) from National Institute of Animal Science (RDA, Korea) were divided into 6 groups (15 birds/group) and were fed with meat-type duck diets for 8 wk old. When ducks grew at specific wk (6, 7 and 8 weeks), 2 ducks per group were slaughtered at 6, 7 and 8 wk old. Myristic acid (C14:0) and palmitic acid (C16:0) of saturated fatty acid (SFA) were the highest and arachidonic acid of unsaturated fatty acid (USFA) was the lowest at the age of 6 weeks old (P<0.05) at the age of 6 weeks old among treatments. Stearic acid of SFA was the highest at the age of 7 weeks old among treatments. There was no significant difference on other fatty acids among treatments. SFA and USFA have significant difference at the age of 8 weeks (P<0.05). Histidine, leucine, lysine, methionine, phenylalanine and threonine of essential amino acid increased with passing weeks (P<0.05). There was no significant difference on isoleucine and valine (P>0.05). Every non-essential amino acids were the highest at the age of 8 weeks among treatments (P<0.05). In conclusion, fatty acid contents and amino acid contents increased until the age of 8 weeks old, but further research was needed because of deficiency of data to suggest the correct shipping time.

• Korean Journal of Agricultural Science
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• v.13 no.1
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• pp.147-150
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• 1986

Fourteen Korean native goats were examined to obtain physiological basic data on electrolyte contents in serum and rumen juice. In addition, pH and total number of ciliates in the rumen juice were investigated. The results obtained were as follows: 1. The serum $Na^+$, $K^+$ and $Cl^-$ levels were $151.9{\pm}4.5(145-160)mEq/l$, $8.1{\pm}1.5(5.3-10.0)mEq/l$ and $104.6{\pm}4.6(99-112)mEq/l$, respectively. 2. $Na^+$, $K^+$ and $Cl^-$ values in the rumen juice were $104.7{\pm}15.8(70-131)mEq/l$, $38.2{\pm}9.9(18-58)mEq/l$ and $14.1{\pm}4.3(8-24)mEq/l$, respectively. 3. The pH of the rumen juice was $5.6{\pm}0.3(5.3-6.5)$ and the total number of ciliates were $2.59{\pm}0.8(0.64-3.29){\times}10^6/ml$.