Comparative pigmentation efficiency of high dietary levels of apo-ester and Tagetes on the quality traits of whole liquid egg of two strains of laying hens.

The yolk pigmentation is considered one of the most important factor in the evaluation of egg quality and different pigment sources such as feed raw materials (maize, maize gluten, alfalfa meal), flower extracts as well as standardised synthesised products can be used in hen feeding for this purpose. A trial was carried out to compare the effects of the dietary supplementation of high doses of either synthetic pigment such as ethyl ester of -apo-8’-carotenoic acid (apo-ester) or natural pigments, mainly lutein and zeaxanthin, extracted from Tagetes erecta, on egg quality of two strains of hens laying brown shell eggs (ISA brown) and white shell eggs (HyLine W36). In total 192 hens (96 + 96) aged 40 weeks were used and the trial lasted 20 weeks. The hens of each strain were divided into six groups and fed a corn-soybean basal diet supplemented either with 40, 60 and 80 ppm of apo-ester or 120, 180 and 240 ppm of Tagetes, since it is widely accepted that the relative efficiency of apo-ester, compared to lutein and zeaxanthin from Tagetes, is 3 to 1. Productive performances of hens (feed intake, feed conversion, rate of laying, mortality), physical properties of eggs (whole egg, yolk and albumen weights) were recorded as well as whole liquid egg colour evaluated by CIE L*, a*, b* system and β-carotene equivalents. The egg pigmentation raised linearly and significantly (P<0.01) as the dietary levels of apo-ester increased (from 66 to 105 ppm for ISAbrown and from 58 to 103 for HyLine), but this did not occur when Tagetes supplementation was used. The amount of β-carotene equivalents in liquid egg of Tagetes groups was almost constant varying the pigment dietary dose and was significantly lower (P<0.01) than in apo-ester groups. In both hen strains, liquid egg redness (a*) and yellowness (b*) were higher with apo-ester supplementation. Both pigment source and level of inclusion had no significant effects on productive performances. On the contrary physical egg parameters were highly affected (P<0.01) by strain: yolk/albumen and yolk/egg ratio were higher in the HyLine hens. The trial confirms that, in spite of the higher level of Tagetes supplementation, apo-ester has a better efficiency in whole liquid egg pigmentation. Moreover ISA brown hens showed a better ability to absorb dietary carotenoids than the HyLine ones.