• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.740-748
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• 2018

This study was conducted to investigate the effects of dietary supplementation of enzyme complex (metalloprotease and xylanase) on growth performance, carcass characteristics and meat storability of broiler chickens. The experiment utilized a 2 (basal and low spec diets) ${\times}$ 3 (0, 0.5 or 1 g/kg of enzyme supplementation) factorial arrangement. A total of 360 male Ross broilers were randomly assigned into the following six groups: BD-T0 (basal diet + enzyme complex 0 g/kg), BD-T1 (basal diet + enzyme complex 0.5 g/kg), BD-T2 (basal diet + enzyme complex 1 g/kg), LD-T0 (low spec diet + enzyme complex 0 g/kg), LD-T1 (low spec diet + enzyme complex 0.5 g/kg), LD-T2 (low spec diet + enzyme complex 1 g/kg). Feed and water were provided ad libitum for 42 days, during which time feed intake and body weight were measured at one-week intervals. After the feeding trial, chickens were slaughtered by exsanguination and samples were collected. Feed intake was lower in the enzyme supplemented groups than the non-supplemented groups (p<0.05), as were body weight and gain (p<0.05). Thus, the feed conversion ratio improved in the enzyme supplemented groups relative to the non-supplemented groups (p<0.05). The carcass rate and production index were also significantly improved by supplementation with enzyme complex (p<0.05). Finally, the thiobarbituric acid reactive substances (TBARS) values were lower in the enzyme supplementation groups after 6 storage days (p<0.05). In conclusion, dietary supplementation with enzyme complex including metalloprotease and xylanase improved growth performance, carcass characteristics, and storability of broiler chicken meat.

• Korean Journal of Poultry Science
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• v.48 no.2
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• pp.91-100
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• 2021

The study determined the effects of stock density (SD) and energy level (EL) on growth performance, serum biochemistry, and meat quality in Korean native chickens. A total of 240 chickens were randomly assigned to one of the four treatments including two stock density (low, 14, and high, 16 chickens per m²) and two energy level (low, 2,950, 3,000, 3050 ME kcal/kg, and high 3,150, 3,200, 3,250 ME kcal/kg, for starter, grower, and finisher, respectively). During the whole period of the experiment, the chickens were fed ad libitum. The greater final body weight and weight gain were achieved in chickens fed high energy diet, whereas the final body weight and weight gain were significantly reduced in high-density treatment compared with the low density. Chickens in low-density groups had a higher feed intake compared with high-density treatment, however, the energy level did not affect the feed intake. An improved overall feed conversion ratio was detected in the high energy treatment. There was a significant interaction between stock density and energy level on cholesterol concentration. The concentration of aspartate transaminase in serum was increased by higher stock density. There was a significant treatment interaction on IgM levels. Moreover, the carcass rate was significantly increased in the high energy level treatment. Based on the findings, we suggest that rearing chickens in low density with high dietary energy levels could be beneficial by improving the growth performance.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.181-188
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• 2022

This study was conducted to investigate the effects of the metabolic energy levels of Korean native chicken breeder diets on laying performance, egg quality, fertility and hatchability. On the basis of dietary metabolic energy values (2,800, 2,700, and 2,650 kcal/kg), 168 twenty-week-old 'Woorimatdag' breeders (maternal line) were divided into three treatment groups (four replications per treatment with each replicate containing 14 birds) and reared until 32 weeks of age. We found that the body weight of hens increased with age, although there were no significant differences among treatments with respect to body weight or egg weight. Egg production ratio at 20-24 and 24-28 weeks of age tended to be low in birds fed the 2,700 and 2,650 kcal/kg diets, although the differences among treatments were none significant. Feed intakes was significantly decreased as the metabolic energy level reduced (P<0.05). There were no significant differences among treatments with respect to feed conversion ratio or the strength and thickness of eggshell. Similarly, we detected no significant differences among the three metabolic energy levels with regards to fertility, hatchability, or chick weight. In conclusion, our findings indicate that during the initial phase of laying, the metabolic energy level of 'Woorimatdag' breeder diets could be lowered to 2,700 kcal/kg without significantly influencing the laying performance of breeders or egg quality, fertility and hatchability, and chick weight.

• Journal of Food Hygiene and Safety
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• v.37 no.3
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• pp.136-142
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• 2022

The research aims to develop a rapid and easy analytical method for methoprene using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple, highly sensitive, and specific analytical method for the determination of methoprene in livestock products (beef, pork, chicken, milk, eggs, and fat) was developed. Methoprene was effectively extracted with 1% acetic acid in acetonitrile and acetone (1:1), followed by the addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium acetate. Subsequently, the lipids in the livestock sample were extracted by freezing them at -20℃. The extracts were cleaned using MgSO₄, primary secondary amine (PSA), and octadecyl (C₁₈), which were then centrifuged to separate the supernatant. Nitrogen gas was used to evaporate the supernatant, which was then dissolved in methanol. The matrix-matched calibration curves were constructed using 8 levels (1, 2.5, 5, 10, 25, 50, 100, 150 ng/mL) and the coefficient of determination (R²) was above 0.9964. Average recoveries spiked at three levels (0.01, 0.1, and 0.5 mg/kg), and ranged from 79.5-105.1%, with relative standard deviations (RSDs) smaller than 14.2%, as required by the Codex guideline (CODEX CAC/GL 40). This study could be useful for residue safety management in livestock products.

• Journal of Animal Science and Technology
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• v.65 no.2
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• pp.336-350
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• 2023

Two experiments were conducted in this research. Experiment 1 investigated the spatial expression characteristics of calcium (Ca) and phosphorus (P) transporters in the duodenum, jejunum, and ileum of 21-day-old broilers provided with adequate nutrient feed. Experiment 2 evaluated the effects of dietary vitamin D₃ (VD₃) concentration (0, 125, 250, 500, 1,000, and 2,000 IU/kg) on growth performance, bone development, and gene expression levels of intestinal Ca and P transporters in 1-21-day-old broilers provided with the negative control diet without supplemental VD₃. Results in experiment 1 showed that the mRNA levels of calcium-binding protein 28-kDa (CaBP-D28k), sodium-calcium exchanger 1 (NCX1), plasma membrane calcium ATPase 1b (PMCA1b), and IIb sodium-phosphate cotransporter (NaPi-IIb) were the highest in the broiler duodenum. By contrast, the mRNA levels of inorganic phosphate transporter 1 (PiT-1) and 2 (PiT-2) were the highest in the ileum. Results in experiment 2 showed that adding 125 IU/kg VD₃ increased body weight gain (BWG), feed intake (FI), bone weight, and percentage and weight of Ca and P in the tibia and femur of 1-21-day-old broilers compared with the negative control diet (p < 0.05). The rise in dietary VD₃ levels from 125 to 1,000 IU/kg further increased the BWG, FI, and weights of the bone, ash, Ca, and P (p < 0.05). No difference in growth rate and leg bone quality was noted in the broilers provided with 1,000 and 2,000 IU/kg VD₃ (p > 0.05). Supplementation with 125-2,000 IU/kg VD₃ increased the mRNA abundances of intestinal Ca and P transporters to varying degrees. The mRNA level of CaBP-D28k increased by 536, 1,161, and 28 folds in the duodenum, jejunum, and ileum, respectively, after adding 1,000 IU/kg VD₃. The mRNA levels of other Ca and P transporters (PMCA1b, NCX1, NaPi-IIb, PiT-1, and PiT-2) increased by 0.57-1.74 folds by adding 1,000-2,000 IU/kg VD₃. These data suggest that intestinal Ca and P transporters are mainly expressed in the duodenum of broilers. Moreover, the addition of VD₃ stimulates the two mineral transporter transcription in broiler intestines.

• Korean Journal of Poultry Science
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• v.50 no.2
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• pp.101-108
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• 2023

This study was conducted to investigate the appropriate levels of crude protein (CP) and phytase in the diet of broiler chicks in order to reduce nitrogen and phosphorus contents in feces while maintaining performance of broilers. Six hundred forty-eight 1-day-old male broilers (41.9±0.91 g) had a total of 3 × 3 complex factor of 3 levels of CP (22%, 21%, 20%) and 3 levels of phytase (1,000, 800, 500 FTU/kg) in the diet. Divided into 9 treatments, 4 replications per treatment, 18 birds per replication, were completely randomly assigned and reared in a metabolic cage for 7 days. Seven-day-old body weight (BW) and body weight gain (BWG) of broilers were significantly lower at CP 20% treatment (P<0.05), and feed conversion ratio (FCR) was significantly lower at CP 21% and phytase 800 FTU/kg treatment (P<0.05). Nitrogen and phosphorus contents in chicken excreta were significantly lower in CP 20% and phytase 500 FTU/kg treatment, respectively (P<0.05). Interactions between CP and phytase in the feed were shown for nitrogen and phosphorus in feces (P<0.05). In conclusion, considering the broiler performance and excretion contents of nitrogen and phosphorus, it is thought that CP and phytase levels of broiler chicks diet can be reduced by 21% and 800 FTU/kg, respectively.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.213-229
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• 2023

This study aimed to investigate the effects of beak trimming and crossbreeding-combinations on the productive performance and stress response levels of Korean native chickens. The study divided 248 individuals from six crossbreeding-combinations into two groups: one underwent beak trimming, and the other did not. The survival rate, body weight, egg production rate, egg quality, feather damage score, HSP-70 gene expression level, H/L ratio, and intracellular DNA damage rate were measured and analyzed. The results showed that the beak-trimmed group had significantly higher survival rates and hen-housed egg production compared to the non-beak-trimmed group (P<0.05). Feather damage and DNA damage rates were significantly lower in the beak-trimmed group (P<0.05). On the other hand, there were no significant differences between the two groups in adult body weight, hen-day egg production, egg quality, HSP-70 gene expression level, and H/L ratio. Among the crossbreeding-combinations, there were significant differences in survival rate, body weight, feather damage score, egg quality, and DNA damage rate (P<0.05), while egg production rate, HSP-70 gene expression level, and H/L ratio showed no significant differences. There was an interaction between beak trimming and crossbreeding-combinations in some traits. In conclusion, beak trimming in Korean native chickens has a positive impact on productive performance, and in terms of stress response, beak trimming may not act as a stress factor or may even reduce stress after the growing period. Furthermore, there were differences in productive performance and stress response levels among crossbreeding-combinations, but the effects of beak trimming were similar across these combinations.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.361-372
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• 2023

Organotin pesticide is used as an acaricide in agriculture and may contaminate livestock products. This study aims to develop a rapid and straightforward analytical method for detecting organotin pesticides, specifically azocyclotin, cyhexatin, and fenbutatin oxide, in various livestock products, including beef, pork, chicken, egg, and milk, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction process involved the use of 1% acetic acid in a mixture of acetonitrile and ethyl acetate (1:1). This was followed by the addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium chloride. The extracts were subsequently purified using octadecyl (C₁₈) and primary secondary amine (PSA), after which the supernatant was evaporated. Organotin pesticide recovery ranged from 75.7 to 115.3%, with a coefficient of variation (CV) below 25.3%. The results meet the criteria range of the Codex guidelines (CODEX CAC/GL 40). The analytical method in this study will be invaluable for the analysis of organotin pesticides in livestock products.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.319-331
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• 2023

Aminoglycoside antibiotics, also known as aminoglycosides (AGs), are veterinary drugs effective against a wide range of gram-negative and gram-positive bacteria. Owing to their recent use in cultured meats, it has become essential to establish an analytical method for safety management. AGs are highly polar compounds, and ion-pair reagents (IPRs) are used to ensure component separation. Owing to the high possibility of potential mechanical problems resulting from IPR addition to the mobile phase, an analytical method in which IPRs are added directly to the vial was explored. In this study, methods for analyzing 10 AGs via liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the addition of two IPRs were validated for selectivity, detection limit, quantitation limit, recovery, and precision. The detection limit was 0.0001-0.0038 mg/kg, the quantification limit was 0.004-0.011 mg/kg, and the linearity (R²) within the concentration range of 0.01-0.5 mg/kg was over 0.99. Recovery and precision (expressed as relative standard deviation) evaluated in the two matrices (beef and cell culture media) ranged from 70.7% to 120.6% and 0.2% to 24.7%, respectively. The validated AG analytical method was then applied to 15 meats prepared from chicken, beef, and pork, and 6 culture media and additives used in cultured meat. No AGs were detected in any of the 15 meats distributed in Korea; however, streptomycin and dihydrostreptomycin were detected at levels ranging from 695.85 to 1152.71 mg/kg and 6.35 to 11.11 mg/kg, respectively, in the culture media additives. The LC-MS/MS method coupled with direct addition of IPRs to the vial can provide useful basic data for AG analysis and safety evaluation of meats as well as culture media and additives for cultured meats.

• Korean Journal of Agricultural Science
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• v.2 no.1
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• pp.9-47
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• 1975

These experiments were caried out to study the effects of caponization and various hormone treatments upon meat production and improvement of meat quality of growing chicken. Sixtyseven days old 160 New Hampshire cockerels were treated and growth rate, carcass yield, change of weight of individual organs, meat composition and change of amino acid were measured and analysed. Otherwise change of testis and thyroid gland by hormone treatment were investigated histologically. The results obtained were as follows. 1. The effectst of caponization and hormone treatment upon meat production were; 1) Body weight of cockerels in D. E. S. group without caponization was increased. upon 96.86% than initial period and A. C. T. H. group was 104.22% but other groups and all carponization groups were lighter than those of control group. 2) Weekly body gain of D. E. S. group without caponization was best showing the significance (102.69 g) and the group with caponization were lower than those groups without caponization. 3) Carcass yield was best in Testo. group without caponization (831.2 g) and the group with caponization were lower than the group without caponization. 4) Carcass rate was highest in A. C. T. H. group with caponization and (67.22%) lowest in Testo. group without caponization (63.37%), but any significance was not recognized. 2. The effects of caponizatitn and hormone treatments upon the coposition of meat and amino acids were; 1) Any significance was not recognized between treated and untreated group about change of moisture, crude protein, crude ash and glycogen contents in meat. 2) Fat co tent in muscle in the all treated groups were higher than that of control group. 3) Extracts of group without caponization were higher than those of groups with caponization. 4) Lysin contents were highest in D. E. S. group with caponization (11. 12/ 16.0 g N) and generelly Testo. group was lower compared with D. E. S. group. 5) Histidine and Arginine contents were higher in the groups with caponization than without caponization. 6) Aspartic acid content were higher in D. E. S. group and A. C. T. H. group without depend on caponization. 7) Treonine content was higher in Testo. group without caponization and in the group with caponization and without hormone treatment compared with those of control group without caponization. 8) Serine content was decreased in the group with caponization and increased by D. E. S. and A. C. T. H treatment groups and glutamic acid was also decreased in Testo. group with out caponization. 9) Cystine content was decreased by Testo. treatment and was not appeared in Testo. group without caponization. 10) Valine content was lower in control group with caponization but significance was not recognized between other groups and control group without caponization. 11) Glycine, Alanine, Methionine. Isoleucine, Leucine, Thyrosine and Phenylalanine contents were not so difference between hormone treated groups and control group without caponization. 3. The effects of caponization and hormone treatment upon the change of organs were: 1) The weight of all organs were heaviest in D. E. S. group without caponization (18.5g) and lightest in A. C. T. H. group without caponization (155. 3g) but no significance was recognized between hormone treatment groups. 2) Heart weight was heaviest in D. E. S. group without caponization (7.46 g) and lightest in Testo. group without caponization (5.95 g). 3) Liver weight was heaviest in D. E. S. group without caponization(32.89g) and lightest in hormone untreated group with caponization(29.66g). Significance was not recognized. 4) Spleen weight was heaivest in Testo. group with caponization (3.22 g) and lightest in D. E. S. group without caponization(2.00g) in contrast with the other groups. High significance was recognized among the groups (P<0.01). 5) Cloacal thymus weight was lightest in D. E. S. group with or without caponization compared with control group without caponization. High significance was recognized among the groups. 6) Muscle fat content was not appeared in A. C. T. H. group with caponization, but it was highly increased in D. E. S. group with or without caponization. 7) Testis weight was lightest in D. E. S. group (0.38g) compared with control group (2.66g). Significance was recognized among the groups. 8) Large intestine, small intestine and cecum weight and length were heavier and longer in D. E. S. group without caponization and control group without caponization was lighter than those of hormone treated groups. 4. The effects of caponization and hormone treatment upon histological change of testis and thyroid gland: 1) The histological change of testis was significantly appeared in D. E. S. group that seminifirous tubles was slowly atrophied, the funtion of spernatogenesis was ceased, spermatocyte was changed as degeneration by pyknosis and karyorrhexis and interstitial cell was also atrophied, but in Testo. and A. C. T. H. group were similar as control group. 2) The histological change of thyroid gland in Testo. and A. C. T. H. groups without caponization were similar to that of control group without caponization, but in D. E. S. group without caponization, was changed squamously. Thyroid gland of the groups with caponization, epithelium of was atrophied and changed squamously as degeneration by pyknosis and karyorrhexis and the function of thyroid gland was slowly ceased in colloid and in hormone treated group with caponization.