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In order to study the effects of apo-ester and canthaxanthin on yolk pigment in laying hens, a total of 1 440 Hyline brown laying hens were allocated into 30 treatments with four replicates of 12 hens each. Hens in the control group were fed the wheat-soybean basal diet, and the apo-ester experimental group was supplemented with apo-ester (0, 4, 8, 16 mg·kg-1 and 32 mg·kg-1) in the basal diet, and the apo-ester group was supplemented with apo-ester (0, 4, 8, 16 mg·kg-1 and 32 mg·kg-1) and canthaxanthin (1, 2, 3 mg·kg-1 and 4 mg·kg-1) in the basal diet. The pre-test period was 7 days and the experimental period was 28 days. To observe the the effects of apo-ester and apo-ester with canthaxanthin combination on yolk color. The results suggested that compared with the control group, the addition of apo- ester could significantly enhance the NHU-YCF value of fresh eggs by 7.13- 12.38 grades, elevate the NHU-YCF value of cooked egg yolks by 0.35-6.73 grades, and the yolk redness value (a value) and yellowness value (b value) were significantly increased, the luminosity value (L value) was significantly decreased. The apo-ester content in egg yolk exhibited a significantly positive correlation with the dietary apo-ester content (R² =0.956 3). The combination of apo-ester and canthaxanthin could significantly improve the color of egg yolk, and the sensitivity of canthaxanthin to egg yolk coloring was higher than that of apo-ester, and the combination of apo-ester and canthaxanthin was more economical to improve the color of egg yolk of laying hens. [ABSTRACT FROM AUTHOR]

Abstract: This study was conducted to evaluate the effects of diets including 0, 5, 10, 15, 25, and 40% alfalfa meals (containing 0, 20, 40, 60, 100, and 160 mg total carotenoids/kg diet, respectively) and 60 mg apo-ester, a synthetic carotenoid/kg diet on skin pigmentation, growth, feed utilization and survival of a red variety of goldfish, Carassius auratus, with average initial weight of 10.3 g, for a rearing period of 60 days. The pigmentation degree in skin of goldfish increased significantly with increasing inclusion of alfalfa up to 25% level in the diet (P <0.05). However, the alfalfa inclusion over that level did not lead to more total carotenoid accumulation in the skin of fish. The diets including apo-ester and 15% alfalfa, both of which contained 60 mg carotenoid/kg diet, had similar effects on total carotenoid deposition in the skin of fish. Alfalfa addition of 25% or higher in the diet had an adverse effect on growth of fish compared to the control group (P <0.05). A similar phenomenon was observed in feed conversion ratio but at the 40% alfalfa inclusion level (P <0.05). However, no significant difference was observed in the survival of the fish. The present results demonstrate that alfalfa can be successfully used as an alternative natural carotenoid source to the synthetic apo-ester in goldfish diets. Our data indicates that 15% is a suitable dietary level of alfalfa to ensure good pigmentation, acceptable growth and feed utilization in goldfish. [Copyright &y& Elsevier]