Genotype and Genotype x Moulting Technique Effects on Egg Quality Indices of Shaver Brown and Nigerian Heavy Ecotype Hens Subjected to Induced Moulting
Cosmas Chikezie Ogbu *
Department of Veterinary Biochemistry and Animal Production, College of Veterinary Medicine, Michael Okpara University of Agriculture Umudike, Abia State, Nigeria.
Sampson Ndifereke
Department of Animal Science, Faculty of Agriculture, University of Nigeria Nsukka, Enugu State, Nigeria.
Ikechukwu Reginald Igwe
Department of Veterinary Biochemistry and Animal Production, College of Veterinary Medicine, Michael Okpara University of Agriculture Umudike, Abia State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Objective: This study evaluated the effects of genotype, moulting technique, and their interaction on egg quality indices in Shaver Brown and Nigerian heavy ecotype hens during induced moulting.
Methodology: The study used a 2 × 3 factorial arrangement in a completely randomised design. Ninety eggs (45 per genotype) obtained from 240 hens (120 per genotype), distributed into three groups per genotype (40 hens per group), were analysed. The control groups were fed a layer ration, ZnO groups were fed 20,000 ppm Zn in layer ration, while fasting groups were deprived of feed. All groups received drinking water ad libitum. Egg quality was assessed using eggs no more than eight days after oviposition; the eggs were stored at 15°C until evaluation. The measured quality traits included egg, albumen, yolk, and shell weights (EW, AW, YW, and SW); egg length (EL), diameter (ED), surface area (ESA), surface area per unit egg weight (SAUW), specific gravity (ESG), and shape index (ESI); albumen and yolk diameters (AD, YD), heights (AH, YH), indices (AI, YI), and ratios (AR, YR); yolk/albumen ratio (Y/A), and Haugh unit (HU); shell thickness (ST), ratio (SR), density (SD), and compression fracture force (SCFF); and eggshell calcium, zinc, and phosphorus contents.
Results: Genotype, moulting technique, and their interaction significantly affected several egg-quality indices (P ≤ .044). Within each genotype, moulting hens produced eggs with lower albumen, yolk, and shell quality indices but higher values for egg size, yolk traits, and shell mineral contents than non-moulting control hens (P ≤ .025). Egg weight, surface area, albumen content, and shell compression fracture force did not differ significantly between the moulting and control groups (P > .05).
Conclusion: Although moulting influenced several egg quality indices, eggs produced during the moulting period retained acceptable external and internal quality.
Recommendation: Eggs laid by moulting hens could be marketed as table eggs or breakers.
Keywords: Egg quality, induced moulting, genotype, shaver brown, Nigerian heavy ecotype, fasting, zinc oxide, albumen quality, yolk quality, eggshell quality