2001 Volume 72 Issue 2 Pages 147-153
Two experiments were conducted to investigate age-dependent changes of meat color of broiler chickens and the effects of feeding Phaffia rhodozyma, a yeast containing high levels of astaxanthin (Ax), with special reference to the feeding duration and bird age at the beginning of feeding. Experimental diets were supplemented or not with cell wall-fractured Phaffia yeast, with the yeast-supplemented diet containing 20ppm Ax. The feeding of the experimental diets commenced from 3 to 8 weeks of age in Experiment 1, and the diets were given for 2 weeks from each of 1, 2, 3, 4, 5 and 6 weeks of age in Experiment 2. The lightness (L* value) of all edible meats was slightly influenced by the age of birds but not by the feeding with the yeast-supplemented diet. The redness (a* value) of thigh (Sartorius), breast (Pectoralis superficialis) and sasami (Pectoralis profundus) meats tended to decrease with the age on a week-to-week basis, while that of thigh meat (Semitendinosus) was not affected by age. Feeding with the yeast-supplemented diet from 3 weeks of age increased a* values in all edible meats, with most of the increases being statistically significant. The extent of the increase in a* values was slightly pronounced in breast and salami meats when the yeast-supplemented diet was fed for 5 weeks prior to market (at 8 weeks of age). The yellownesss (b* value) of breast and sasami meats increased with a prolonged feeding with the yeast-supplemented diet after 3 weeks of age. The feeding for 2 weeks with the yeast-supplemented diet in Experiment 2 increased a* values in all edible meats irrespective of the age at the beginning of feeding. The b* values of thigh and breast meats were significantly, but to a small extent, increased by feeding for 2 weeks with the yeast-supplemented diet. It is suggested that the feeding with Phaffia yeast-supplemented diets intensifies mainly the redness of broiler meats, while prolonged feeding of the yeast diet intensifies meat yellowness.
