text new page (beta)
English (pdf)
Article in xml format
Automatic translation
Cited by SciELO 
Cited by Google 
Similars in
SciELO 
Similars in Google 
Permalink
INTRODUCTION
Despite the increasing trends in consumption of skinless raw products or further-processed chicken, a significantly large volume of whole chicken and parts with skin is cur rently being commercialised (Sirri et al 2010). In China, Italy, Mexico, among other countries, consumer preference for yellow chicken is the main commercial driver since this trait is associated with adequate bird health and product freshness (Fletcher 1999, Breithaupt 2007, Liu et al 2008). Carotenoids are widely distributed in nature. They are syn thesized by microorganisms and plants, and deposited in animal tissues throughout the food chain. Lutein, a type of carotenoid, is a xanthophyll found in large concentrations in the petals of the Aztec marigold flower (Tagetes erecta). Since lutein has the ability to accumulate in the chicken skin and fat, it is widely used as a natural yellow pigment in the broiler industry (Hadden et al 1999, Kotake-Nara and Nagao 2011). The degree of cutaneous pigmentation in the chicken is variable. In certain regions, even within the same country, the dietary xanthophylls concentration can be so high that it may represent 10% of the feed cost (Muñoz-Díaz et al 2012).
In Mexico, the inclusion of 80 mg/kg of xanthophylls in broiler diets during the last 4 weeks prior to slaughter is commonly used to achieve an intense yellow coloration in the skin and shanks (Cuca et al 1996). Since skin pig mentation is a time and dosage-depending process, skin yellowness is expected to increase along with the time of consumption (Bilgili and Hess 2010).
Previous research studies have indicated that female chickens can achieve more intense skin pigmentation in comparison with male chickens. This phenomenon might be associated with hormonal influences and fat deposition in the females (Muñoz-Díaz et al 2012, Tyczkowski and Hamilton 1986, Martínez et al 2004, Le Bihan-Duval et al 1998, Rance et al 2002). Therefore, the objective of the current study is to determine the saturation point of absorption and cutaneous deposition of yellow xanthophylls (XA) in males and females broilers.
MATERIAL AND METHODS
Two hundred and sixteen 1-d-old Ross 308 broiler chickens (108 males and 108 females) were obtained from a commercial hatchery and housed in Petersime® battery brooders within an open-sided house during the whole experiment. The starter diet (1 to 21 d of age) was based on sorghum-soybean meal, and amino acids and protein were added to meet the primary breeder recom mendations for the bird strain (table 1) (Aviagen 2009). At 21 d of age, the birds were randomly assigned to 6 dietary treatments with 6 replications (3 replications for each sex) of 6 birds each, and consisted of six levels of dietary xanthophylls from Aztec marigold flower (Florafil 93, 30g/kg, VEPINSA, Los Mochis, Sinaloa, Mexico): 65, 92, 119, 146, 173, and 200 ppm (Muñoz-Díaz et al 2012, Frade-Negrete et al 2016). From day 21 to 49 the diets were based on sorghum-soybean meal, and were formulated to meet the nutrient recommendations of the primary breeding company (table 2) (Aviagen 2009). The feed was provided ad libitum in a mash form.
Table 1 Composition of the starter diet for broiler chickens from 0 to 21 d of age.
123Vitamin premix supplied the following per kg: vitamin A, 20,000,000 IU; vitamin D3, 6,000,000 IU; vitamin E, 75,000 IU; vitamin K3,9 g; thiamine 3 g; riboflavin, 8g; pantothenic acid, 18 g; niacin, 60 g; pyridoxine, 5 g; folic acid, 2 g; biotin, 0.2g; cyanocobalamin 16 mg; ascorbic acid 200 g; Mineral premix supplied the following per kg: manganese, 120 g; zinc, 100 g; iron, 120 g; copper, 12 g; iodine, 0.7 g; selenium, 0.4 g; cobalt, 0.2 g Butylated hydroxytoluene and buthoxyquin.
Table 2 Composition of the diets for broiler chickens from 21 to 49 d of age (kg).
1234Florafil 93 powder (VEPINSA): Concentration of 30g/kg of Xanthophyll from aztec marigold flower (Tagetes erecta), stabilized with antioxidant and incorporated into a mixture of inert carriers. Vitamin premix supplied the following per kg: vitamin A, 20,000,000 IU; vitamin D3, 6,000,000 IU; vitamin E, 75,000 IU; vitamin K3,9 g; thiamine 3 g; riboflavin, 8g; pantothenic acid, 18 g; niacin, 60 g; pyridoxine, 5 g; folic acid, 2 g; biotin, 0.2g; cyanocobalamin 16 mg; ascorbic acid 200 g; Mineral premix supplied the following per kg: manganese, 120 g; zinc, 100 g; iron, 120 g; copper, 12 g; iodine, 0.7 g; selenium, 0.4 g; cobalt, 0.2 g Butylated hydroxytoluene and buthoxyquin.
This experiment was conducted in accordance with the Guidelines for the Care and Use of Agricultural Animal in Research and Teaching, 3rd ed., 2010 and the Guidelines of the Institutional Animal Care and Use Committee of the Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México.
MEASUREMENTS
Growth performance. Body weight gain, feed consumption, and feed conversion adjusted for mortality were recorded on a weekly basis.
Skin yellowness. Throughout the experiment and twice a week between 21 d and 49 d of age, skin yellowness was measured in vivo in all birds on the right apterial late-ro-pectorial area, throughout the experiment, L*, a*, and b* values were determined as an average of 3 measurements using a CR400® Minolta chromameter (Chroma Meter, Model CR-400, Minolta Corp., Ramsay, NJ).
Plasma pigment. On the same d that skin yellowness was measured, a 2-ml blood sample was collected from 3 birds per pen via radial vein puncture, and mixed with EDTA at 2% as an anticoagulant. The blood samples were stored in the dark and refrigerated until further processing. Plasma xanthophylls were determined according to the method reported by Allen (1987).
STATISTICAL ANALYSIS
Before performing data analysis, the normality of data distribution was assessed with the Shapiro-Wilk test and the homocedasticity of the variances with the Levene test. The independence of the data was also reviewed. Growth performance and concentration of plasma xanthophylls data were analysed through ANOVA for a 6 X 2 factorial arrangement, where the first factor was the xanthophylls added at six levels, and the second factor was sex at two levels. When the level of xanthophylls was found to have a significant effect (P<0.05), treatment means were separated using Tukey's multiple comparison procedure. Data for skin yellowness and concentration of plasma xanthophylls according to the consumption time were fitted into a mul tiple regression model in which the independent variables were the dietary xanthophylls level (X1), the days of consumption (X2) and the bird's sex (X3), the latter being used as an indicative variable (0 = females; 1 = males). To determine the inclusion of the independent variables in the model, a significance value of P<0.05 was used (Kuehl 2001, Neter et al 1996). In addition, a broken-line model (Robbins et al 1979) was used to find the time (day) in which the maximum levels of skin yellowing and plasma xanthophylls (saturation point) were reached.
RESULTS
Growth performance results are presented in table 3. Weight gain, feed consumption and feed conversion were not significantly affected by the xanthophylls level (P>0.05). As expected, males had significantly greater weight gain (P<0.05) compared to the females (2,336 g vs 1,975 g, respectively). Feed consumption was significantly greater in males (4,523 g) than in females (4115 g) (P<0.05). Feed conversion was significantly better in males than in females (1.943 kg:kg vs 2.092 kg:kg) (P< 0.05).
Table 3 Growth performance of broiler chickens fed different levels of Aztec marigold flower xanthophylls (Tagetes erecta) from 21 to 49 d of age.
a-f Means with different superscripts within a column differ significantly (P<0.05). 1BW gain from d 21 to 49 of age. *P<0.05.
Total pigment consumption is presented in table 3. The higher pigment consumption was observed in birds fed the highest concentration of dietary xanthophylls (P<0.05).
Skin yellowness at the end of the study was signifi cantly greater for the females than for males (21.94 b* vs 18.17 b*). However, regardless of the bird's sex, there were no significant differences among xanthophyll levels, except for the birds fed 65 ppm of xanthophylls which had significantly the lowest skin pigmentation (table 3).
Regarding plasma xanthophylls only, a statistical dif ference (P<0.05) was found between the groups receiving 65 ppm (35.2 μg / mL) and 173 ppm (47.7 μg / mL); while the rest of the groups were similar among them (P>0.05). Sex and thee interaction sex X doses of xanthophylls in the feed did not affect the concentration of plasma xanthophylls (P>0.05).
Figure 1 shows the effect of increasing dietary xanthophylls levels on skin yellowness (b*) according to sex and consumption time. It was determined that for every 10 ppm of increase in dietary pigment level, skin yellowness was increased by 0.83 b*. For every day that pigment was consumed, skin yellowness increased by 2.24b*. Skin yellowness in female birds was 1.35 b* greater than in male birds. These relationships are explained by the following equation:
Figure 2 shows the results of the analysis of in vivo skin yellowing and days of consumption using the broken line model, where it is observed that the treatment that received 65 ppm of xanthophylls in the feed presented a maximum level of skin pigmentation at 12 days of consumption. The rest of the groups reached the maximum yellowing of the skin 11 days after the beginning of consumption (table 4).
Table 4 Equations to calculate the day of highest level of skin yellowing obtained in vivo and plasma xanthophylls in broiler chickens using the broken line model.
Figure 1 Skin yellowness (b*) response in broiler chickens fed increasing levels of Aztec marigold flower xanthophylls from 21 to 49 d of age.
Figure 2 Time of consumption with the highest level of skin yellowing in chickens fed with different concentrations of yellow xantho-phylls using the broken line model.
Figure 3 Concentration of plasma xanthophylls in broiler chickens fed increasing levels of Aztec marigold flower xanthophylls from 21 to 49 d of age. By using the Broken-line model, the first saturation point was found at 11 days, and at days 21 the plasma concen tration of xanthophylls increased.
Figure 3 shows concentration of plasma xanthophylls versus time of pigment consumption. Results indicated that sex did not influence the concentration of plasma xanthophylls, for every day of pigment consumption plasma XA concentration increased by 8.216 μg/mL. Moreover, for every ppm of xanthophylls in the feed, plasma xanthophylls increased by 0.073 μg/mL. These relationships are explained by the following equation:
DISCUSSION
Dietary xanthophyll level did not have any effect on growth performance, which is in agreement with previous research (Martínez et al 2004, Le Bihan-Duval et al 1998, Pérez-Vendrell et al 2001).
The birds with the lowest skin yellowness values also had the lowest pigment consumption. It is possible that the high levels of dietary pigment might keep high activity of the enzymes that re-esterify lutein for further cutaneous deposition. This would increase skin deposi tion of pigment in contrast with birds fed lower levels of xanthophyll. Enzyme kinetics have shown that as substrate concentration increases, the chemical reaction continues linearly until the enzyme reaches a saturation point (Nelson 2005).
In the current study, highest skin yellowness in live birds were obtained after 18 days of feeding, regardless of the dietary pigment level or the bird's sex (figure 1). By using the broken line model, it was observed that the treatment that received 65 ppm of xanthophylls in the feed presented a maximum level of skin pigmentation at 12 days of consumption; however, it did not reach the yellowing demanded by the market for its commercialization (20 b*). The time needed to achieve maximum skin pigmentation is related to the fact that lutein needs to be transported by plasma low-density lipoproteins and undergo re-esterification by enzyme located in the tissues where lutein deposition occurs (Tyczkowski and Hamilton 1986).
Muñoz-Díaz et al (2012) reported that female birds gained 1.73 b* more than the male broilers, when feeding 75, 108, 141, and 162 ppm of dietary xanthophylls at 6 and 7 weeks of age. Sirri et al (2010) reported that females had a higher level of skin pigmentation post-slaughter in breast, thighs, and shanks (24.9, 22.2 y 56.5 b*) than males (20.4, 18.1, 51.3 b*) after receiving 12 to 15 ppm of dietary xanthophylls. The higher skin pigmentation in female birds has been explained by their higher level of subcutaneous fat, which is one of the target tissues for pigment deposition due to the xanthophyll liposoluble properties (Fletcher 1992).
Breithaupt et al (2003) found no significant differences in plasma pigment concentrations in Leghorn birds after 2 weeks of xanthophylls consumption. This response could be explained by the lower feed consumption observed and the lower concentration of pigment fed to the birds (10 ppm). Kostic et al (1995) reported a lutein peak in plasma at 16 hours post consumption, but found no saturation point. Park et al (1998) measured a saturation point of plasma lutein in mice after 7 days of consumption. Plasma pigment sat uration may be related with the rate of absorption through the intestines, which varies between species and depends upon feed consumption. To the author's knowledge, there is no other research reported where the saturation point of plasma xanthophylls has been determined in broiler chickens. Figure 3 depicts the xanthophylls concentration in plasma as a function of time and quantity consumed (P<0.001). The birds that received the highest concentration of dietary xanthophylls (200 ppm) consumed 879 mg of xanthophylls per bird. This differs from other organs where pigments can be stored and have a higher saturation point. However, there are no studies where the time required attaining a saturation point of plasma xanthophylls or skin pigmentation had been determined. Under certain field situations, when there is a problem of poor skin pigmentation, it is not unusual to increase dietary xanthophylls concentrations to achieve the desired skin pigmentation level in a shorter period of time. However, without knowing what the saturation point of skin pigmentation is over certain time, the pigment is often wasted, which may become very costly. The results of the current study provide some basis to help optimise pigment utilisation at various times of administration and facilitates the decision-making process under practical situ ations. Nevertheless, further insight seems to be necessary to fully understand the physiology of pigment absorption and deposition in broiler chickens.
According to the results obtained in this study, it can be concluded that the sex did not influence the concentration of plasma xanthophylls, for every day of pigment consump tion plasma xanthophylls concentration increased by 8.216 μg/mL. Skin yellowness increased by 0.83 b* for every 10 ppm of dietary xanthophylls increment. For every day that dietary xanthophylls were consumed, skin yellowness increased by 2.24 b*. Skin yellowness in female broilers was greater than in males by 1.35 b*. The highest levels of plasma xanthophylls and skin yellowness were found after 11 ds of feeding according to the broken line model.
