Lesser known indigenous vegetables as potential natural egg yolk colourant in Laying Chickens
A six-week study involving two hundred and fifty (250) Harco black layer birds at point of lay was carried out to investigate the effects of potential natural colourant on performance and egg quality traits. The birds were assigned to five (5) dietary treatments, each containing supplements either of control, baobab leaf (BL), water leaf (WL), red pepper (RP), canthaxanthin (CTX) at 40g/kg feed and 50mg/kg feed of natural and commercial colourants, respectively. Performance records showed no significant (p>0.05) difference in feed intake across supplements of red pepper, water leaf, canthaxanthin and control diet, however baobab leaf treatment had a significantly lower (p<0.05) intake value (94.07g) when compared with other treatments. Body weight gain and hen day production was not significant influenced (p>0.05) by the dietary treatments, though baobab leaf supplement had lowest mean HDP of 48.80%, red pepper and water leaf supplement averaging 52.79%. There was no significant effect (p>0.05) of colourants on egg external traits, compared with the control; canthaxanthin treatment had higher mean egg weight (51.79g), egg length (4.55g), egg breadth (3.29g); red pepper treatment had highest mean shell thickness (0.29g), however these differences were not significant (p>0.05). Yolk height, albumen height, yolk index and Haugh unit were not significantly affected (p>0.05) across treatments. Yolk width was lowest (p<0.05) in baobab leaf treatment (2.54cm); red pepper, water leaf and canthaxanthin had 2.89cm, 2.62cm and 2.89cm, respectively and were not significantly (p>0.05) different from the control (2.73cm). Yolk colour score was significantly highest (p<0.05) in red pepper treatment (7.50); water leaf, baobab leaf and canthaxanthin ranged between 2.25 - 3.31 on the DSM yolk colour, while the control treatment had the lowest yolk colour score of 1.31. The study showed red pepper as a good alternative to commercial yolk colourant. Water leaf and baobab leaf were not good substitutes for canthaxanthin as a yolk colourant.
Keywords: Yolk colourant, Baobab leaf, Water leaf, Red pepper, Canthaxanthin