Genotype and dietary supplementation of ginger (Zingibar officinale) rhizome powder affect egg quality traits of layer chickens

Abstract

This study evaluated the effects of ginger (Z. officinale) rhizome powder on egg qualities of aged commercial and native hens using 160 Shaver Brown (SB) and Nigerian heavy ecotype native hens (HEN). Experimental groups per genotype were control group or basal diet group, and ginger rhizome powder supplemented group (20 g/kg, ginger group). For each genotype, forty (40) hens were assigned to the control group and 120 hens to the ginger group. Each experimental group had four (4) replicates containing 10 hens each for the control groups, and 30 hens each for the ginger groups. The hens were housed individually in laying cages and fed the experimental diets at 125 g/bird/day. Water was given ad libitum and photoperiod was 12 h light and darkness. 80 eggs from SB and 40 eggs from HEN control groups, and 80 eggs/genotype from the ginger groups were used to evaluate egg qualities while 10 shell samples were used to evaluate shell mineral contents for each group. In addition, within genotypes, eggs belonging to the ginger groups were grouped into egg weight and egg shape index grades and assessed for egg qualities. SB eggs had significantly (p ≤ 0.05) higher weight (EW), length (EL), diameter (ED), surface area (ESA), volume (EV), and shape index (ESI); yolk, albumen, and shell weights (YW, AW and SW); albumen height, diameter, and ratio (AH, AD, and AR); shell volume (SV), compression fracture force (SCFF), and calcium content but lower egg specific gravity (ESG), yolk ratio (YR), yolk/albumen ratio (Y/A ratio), shell Zinc, and Phosphorus contents compared to HEN eggs. Ginger groups had higher EW, EL, ESA, EV, YW, YD, YR, AH, AI, Y/A ratio, and shell Zn but lower ESG, YH and YI compared to control groups. SB-ginger group had highest (p ≤ 0.000) AD while HEN-ginger group had highest (p ≤ 0.05) shell Zinc, and Phosphorus contents. EW grades differed significantly in EW, ESA, ESG, ESI and SCFF in the two genotypes while ESI grades differed significantly in ESI and Y/A ratio in SB but in ESI, YI and Haugh unit in HEN. In conclusion, genotype, diet, genotype x diet, EW and ESI grades influenced egg quality traits. These factors are important for egg quality evaluation and genetic improvement.