遊離脂肪酸含量이 높은 動物性脂肪을 肉鷄飼料의 지방원으로 添加 給與하여 그 利用性과 肉質에 미치는 影響을 調査하기 위하여 飼養試驗과 肉質評價試驗을 實施하였다.
飼養試驗은 갓 부화된 肉鷄 수평아리 108 首를 3個處理, 3反復으로 12首씩 나누어 8주간 試驗飼料를 給與하였다. 遊離脂肪酸含量이 各各 15 및 38.6%인 Yellow grease와 Animal fat (상품명)를 前期(0~4週)와 後期(5~8週) 飼料에 各各 3 및 5%씩을 添加 給與하여 격주의 間隔으로 飼料攝取量과 增體量을 調査하였고 試驗終了時 Shank color를 測定하였다. 飼料의 蛋白質과 대사에너지함량은 處理間에 비슷하도록 하였다. 肉質을 評價하기 위해 飼養試驗이 끝난후 各 處理區當 7首씩을 選拔, 도살하여 腹部脂肪의 함량과 가슴살과 다리살에 대한 官能檢査와 가슴살에서 總脂肪含量, 유리지방산합량, 옥도가 및 과산화물가의 化學的 性質을 測定하였다.
脂肪을 添加하지 않은 飼料를 給與한 對照區와 Yellow grease나 Animal fat 添加區는 前期飼料 給與期間동안 세 處理區間에 飼料攝取量, 增體量, 飼料效率에서 아무런 有意差가 나타나지 않았다. 後期飼料 給與期間동안에는 對照區에 비하여 脂肪處理區에서 飼料攝取量은 平均 10.8%, 增體量은 25.0%, 그리고 飼料效率은 11.3%의 改善效果가 있었다. 全體期間(0~8주)으로 보면 飼料攝取量은 8.8%, 增體量은 16.2%, 飼料效率은 6.8%의 改善效果가 있는 것으로 나타났으나 두가지 脂肪 급원간에는 유의한 차이가 없었다.
정갱이의 着色程度는 全般的으로 6.9~7.7 정도의 範圍였고 脂肪添加區들이 약간 떨어지는 경향이 보였으나 세 處理間에 유의한 差異가 없었다.
다리살과 가슴살에 대한 官能檢査 結果는 脂肪을 添加하지 않은 對照區와 脂肪을 添加 給與한 處理區들사이에 아무런 有意差가 나타나지 않았다.
가슴살에 蓄積된 脂肪의 化學的 性質은 對照區에 비해 Yellow grease나 Animal fat를 添加 給與한 處理區에 總 脂肪含量이 各各 7.77, 6.66 및 6.32였고 遊離脂肪酸含量은 9.23, 9.73 및 9.31㎎/g fat, 옥도가는 65.36, 66.89 및 59.25g/100g fat, 그리고 過酸化物價는 9.62, 10.46 및 8.79 meq/㎏ fat이여서 各 處理間에 有意한 差異가 나타나지 않았다. 10日間의 冷藏貯藏(4℃)에 따른 가슴살이의 遊離脂肪酸含量의 變化狀態는 모든 處理區에서 비슷한 煩向을 보여 5日만에 거의 3倍 程度로 增加하였고 그후 10日째까지는 더 이상 變化하지 않았다.
以上의 結果를 綜合할때 본 試驗에 便用한 Animal fat는 遊離脂肪酸含量이 38.6% 정도로 높을지라도 肉鷄에서의 飼料的 價値나 肉質에 미치는 影響에서 Yellow grease와 조금도 차이가 없이 安全하게 使用될 수 있다고 판단된다.
Present experiment was undertaken to compare the effects of two dietary fats whose free fatty acid content was quite different on performances and on meat quality of broilers. Yellow grease or animal fat (trade name) containing 15 or 38.6% free fatty acid, respectively, was added to the broiler starter and finisher diets at levels of 3.0 and 5.0%, respectively.
A total of 108, day - old, male Maniker (Chunho) broiler chicks was alloted to 3 dietary treatments with 3 replications Per treatment. and 12 chicks per replication. Though control diet was not supplemented with fat, the three dietary groups were made isocaloric and isonitrogenous. All the chicks were ad libitum fed the test diets for 8 weeks. Feed intake and body weight were measured every other week. Shank color was measured at the end of feeding trial by Roche Color Fan.
To evaluate meat quality, 7 chicks of mean body weight were selected from each treatment group after the trial. Measurements were made for abdominal fat content, organoleptic scores for thigh and breast, and for contents of total lipids, free fatty acids, iodine values and peroxide values of the breasts.
During the period from 0 to 4 weeks of age, the broilers fed the diets added with fats performed the same as those fed the control diet. However, the body weight gain (25%), feed intake (10.8%) and feed efficiency (11.3%) of chicks fed the fat - supplemented diets, during the finisher period (5 - 8 weeks), appeared significantly improved compared to those of control group (p<0.05). During overall period of 8 weeks, body weight gain, feed intake, and feed efficiency of chicks fed the diets added with fats were, on the average. 16.2, 8.8 and 6.8%, respectively, better than those of control. Meanwhile the performance between the chicks fed diets added with the two different fat sources appeared to be of the same tendency. Though the shank pigmentation was not statistically different among the treatments, the chicks fed the fat - supplemented diets tended to have slightly less pigments than the control.
Organoleptic scores of though or breast of chicks fed the animal fat diet were of the same range as those of the other two groups. The contents of total lipids, free fatty acids, iodine values and peroxide values of breasts from broilers fed the various diets appeared to be in the same ranges among the treatments. The values for control, yellow grease and animal fat groups were 7.77, 6.66 and 6.32% for total lipids, 9.23, 9.73 and 9.31㎎ oleic acid/g fat for free fatty acids, 65.36 63.89 and 59.25 g/ 100g fat for iodine values, and 9.62, 10.46 and 8.79 meq/㎏ fat for peroxide values, respectively. Changes of free fatty acids contents of breast during a storage for 10 days at 4℃ were also not different among the dietary groups.
From the observations in this experiment, it seems possible to conclude that the animal fat containing 38.6% free fatty acid can be used as efficiently as yellow grease in broiler diets without any adverse effects on meat quality.