The fate of lycopene and other carotenoids from feed to egg in two laying hen set-ups

Abstract

Eggs are considered to be a nutritious food, by offering a balanced source of essential amino and fatty acids, minerals, and vitamins. Various Diet factors can modify hen egg traits. Thus, the effects of tomato powder in egg yolk was investigated. The objective of this study was to determine the effect of tomato powder on egg weight, egg’s length and width and yolk colour, carotenoid content, polyphenol and antioxidant content. A total of five hundred and seventy-six eggs, from the two different experimental setups, isolated and farmed were analysed. Research was carried out on twenty LegHorn Brown laying hens, twenty-week-old. The hens were individually caged and divided in four groups of five hens each with three different dietary formulations including the control group. The tomato powder was added to the feed as a feed additive within the treatment formulations; 2, 4, 6 g of tomato powder per 100 g of feed. The laying hens were given a total of 100 g of feed per day and the water ad libitum. The light cycle was set as 16 h light and 8 h dark while the temperature varied between 20oC to 30oC. There was a significant difference between the temperatures in both experimental set ups since in the isolated experiment the temperatures started to rise while the temperatures recorded in the farm experimental setup were high due to other animals within the same area. The weight and shape index of the eggs were not significantly different when comparing between groups, weeks and experimental set-ups. The weight of the eggs was in the isolated and farm experiments 55.65±6.386 g respectively. The shape index of the eggs was in the isolated and farm experiments 75% and 74.95% respectively. Colour index analysis was done by using the DSM Egg Yolk Fan. The egg yolk colour varied along the weeks of the experiment in both isolated and farm experimental setups. The colour index recorded for the isolated experiment of the control group was 5 while in the group 6 g was 14 at the end of the experimental setup. These figures were also similar in the farm experiment. Physicochemical analysis was carried out using UV-Vis spectrophotometry according to AOAC standard. Yolk samples were prepared in a hexane-acetone-ethanol (2:1:1) solvent system. A significant difference was observed along the timeline of the experiment. The results obtained showed that the lycopene and other carotenoids present in the tomato powder as a feed additive was also present in the egg yolk. The yolk lycopene contents in the isolated and farm experiments were 43.84 mg/kg and 35.49 mg/kg, respectively. The β-carotene contents were 35.49 mg/kg and 34.21 mg/kg and the lutein contents were 41.05 mg/kg and 36.43 mg/kg. The chlorophyll A and B were low, with the highest value of Chlorophyll A of 4.88 mg/kg in isolated experiment and 3.87 mg/kg in farm experiment while the Chlorophyll B the highest value in isolated experiment was of 7.74 mg/kg and in the farm setup the highest value was of 6.20 mg/kg Folin Ciocalteu (FC) Test was used to analyse the polyphenolic content in the egg yolk however, no significant difference was found between the polyphenolic content present in the egg yolk. The highest value of 316 mg/g was found in week 4, in the control group of the farm experiment while the lowest value of 108 mg/g was found in week 4, in group 6 g of the isolated experiment. The antioxidant scavenging activity was performed by using the 2,2-Diphenyl-1- picrylhydrazyl (DPPH) method. The antioxidant in the egg yolk was present due to the high carotenoid content found in the egg yolk. The highest value of 26.16 mg/100g was found in week 8, in the control group of the farm experiment while the lowest value of 18.62 mg/100g was found in week 4, in group 6 g of the farm experiment. This experiment indicates that lycopene and other carotenoids, which may be present in industrial food wastes, can be easily incorporated as a feed additive. At these dietary concentrations the lycopene will enhance the other carotenoids present in the egg yolk.