Aydin R, Pariza M W, Cook M E
Animal Sciences Department, University of Wisconsin-Madison, 1675 Observatory Drive, Madison, WI 53706, USA.
J Nutr. 2001 Mar;131(3):800-6. doi: 10.1093/jn/131.3.800.
Dietary conjugated linoleic acid (CLA) decreases yolk 18:1(n-9), induces chick embryonic mortality and alters egg quality. A study was conducted to determine whether olive oil would prevent these adverse effects of CLA. Hens (15 per treatment) were fed diets containing 0.5 g corn oil/100 g (CO), 0.5 g CLA/100 g (CLA), 0.5 g corn oil plus 10 g olive oil/100 g (CO + OO) or 0.5 g CLA plus 10 g olive oil/100 g (CLA + OO). After 74 d of feeding, hens were placed on CO for 10 d. Hens were artificially inseminated weekly. For hatchability studies, fertile eggs were collected daily, stored at 15 degrees C for 24 h and then incubated. After 6 d of feeding, embryonic mortality rates were 15, 100, 8 and 16% in the CO, CLA, CO + OO and CLA + OO groups, respectively. When CLA-fed hens were fed the CO diet, hatchability improved to that of the CO group within 7 d. For fatty acid analysis, three eggs were obtained at the 7 d of feeding. Relative CLA levels of yolk from CO-, CLA-, CO + OO- and CLA + OO-fed hens were 0.11 +/- 0.01, 1.91 +/- 0.16, 0.08 +/- 0.04 and 0.69 +/- 0.07 g/100 g fatty acids, respectively. The ratios of 16:0/16:1(n-7) and 18:0/18:1(n-9) of yolk from CLA-fed hens were approximately 1- and approximately 1.5-fold greater, respectively, compared with those fed CO. OO prevented CLA-induced increases in 16:0 and 18:0 and the decrease in 18:1(n-9) in yolk. Fertile eggs were stored at 4 degrees C for 2 or 10 wk and analyzed for pH or mineral levels. Dietary CLA caused abnormal pH changes of albumen and yolk when eggs were stored at 4 degrees C. The pH of yolk and albumen from CO-fed hens after 10 wk of storage was 6.12 +/- 0.12 and 9.06 +/- 0.03, respectively, versus 7.89 +/- 0.25 and 8.32 +/- 0.16, respectively, in eggs from CLA-fed hens. OO prevented CLA-induced abnormal changes in the pH of albumen and yolks. Eggs from CLA-fed hens had greater iron, calcium and zinc concentrations and lower magnesium, sodium and chloride concentrations in albumen relative to those from hens fed CO. OO prevented CLA-induced mineral exchange between yolk and albumen, presumably by reducing the yolk saturated fatty acids, which are believed to disrupt the vitelline membrane during cold storage. This study suggests that the adverse effects of CLA may be due to the increased level of saturated fatty acids. However, because the addition of olive oil also lowered egg CLA content, the direct role of egg CLA on egg hatchability and quality cannot be ruled out.
膳食共轭亚油酸（CLA）会降低蛋黄中的18:1(n-9)含量，导致鸡胚死亡率升高并改变蛋的品质。本研究旨在确定橄榄油是否能预防CLA的这些不良影响。将母鸡（每种处理15只）饲喂含0.5 g玉米油/100 g（CO）、0.5 g CLA/100 g（CLA）、0.5 g玉米油加10 g橄榄油/100 g（CO + OO）或0.5 g CLA加10 g橄榄油/100 g（CLA + OO）的日粮。饲喂74 d后，将母鸡改喂CO日粮10 d。每周对母鸡进行人工授精。在孵化率研究中，每天收集受精蛋，在15℃下储存24 h，然后进行孵化。饲喂6 d后，CO、CLA、CO + OO和CLA + OO组的胚胎死亡率分别为15%、100%、8%和16%。当饲喂CLA的母鸡改喂CO日粮时，孵化率在7 d内提高到CO组的水平。为进行脂肪酸分析，在饲喂7 d时获取3枚蛋。CO、CLA、CO + OO和CLA + OO组母鸡所产蛋的蛋黄中CLA相对含量分别为0.11±0.01、1.91±0.16、0.08±0.04和0.69±0.07 g/100 g脂肪酸。与饲喂CO的母鸡相比，饲喂CLA的母鸡所产蛋的蛋黄中16:0/16:1(n-7)和18:0/18:1(n-9)的比值分别大约高1倍和大约1.5倍。橄榄油可预防CLA诱导的蛋黄中16:0和18:0含量增加以及18:1(n-9)含量降低。将受精蛋在4℃下储存2周或10周，并分析其pH值或矿物质水平。当蛋在4℃下储存时，日粮CLA会导致蛋白和蛋黄的pH值出现异常变化。储存10周后，饲喂CO的母鸡所产蛋的蛋黄和蛋白pH值分别为6.12±0.12和9.06±0.03，而饲喂CLA的母鸡所产蛋的蛋黄和蛋白pH值分别为7.89±0.25和8.32±0.
