Effects of Strain, Age and the Interrelationships between External and Internal Qualities of Eggs in Two Strains of Layer Chickens in Northern Guinea Savannah Zone of Nigeria

Abstract

An experiment was conducted to determine the differences in body weight (BW), feed intake (FI) and some egg production traits of two strains of layer chickens (Isa Brown and Nera Black) and correlate the relationships between the tested traits. The study commenced when the layers were 26 weeks old and a total of 200 (100 of each strain) were used. Sixty fresh eggs (30 from each strain) were collected at 26^th, 32^nd and 38^th weeks of lay. The results of analysis of variance for main effect of strain revealed significant (P<0.05) differences in BW with Isa Brown (IB) weighing heavier (1978 g) than Nera Black (NB) (1887 g). There was however no strain effect on FI. The values for the external egg quality traits for egg weight, shell weight and shell thickness were found, respectively as 58.06 g <em>vs</em>. 54.26 g, 5.4 g <em>vs</em>. 5.00 g and 0.44 mm <em>vs</em>. 0.31 mm in favour of IB. While the values for internal egg quality traits for albumen weight, yolk weight and yolk height were found, respectively as 36.46 g <em>vs</em>. 33.60 g, 15.60 g <em>vs</em>. 12.26 g and 1.86 cm <em>vs</em>. 1.62 cm in favour of IB. Other traits tested (egg lenght, egg width, albumin height and haugh unit) were unaffected by strain. Main effect of age showed that most of the internal and external egg traits decreased with increase in age of the layers. Yolk weight increased with increasing age of the layers, which implies that eggs from younger birds would be expected to have lower amount of cholesterol. The correlation analysis for most of the tested traits were positive. BW positively and significantly (P<0.05) correlated with FI (0.73) and egg weight (0.54). It was concluded that age numerically decreased most of the tested qualities of egg while srain had significant (P<0.05) effect on BW and some egg quality traits with Isa Brown performing better than Nera Black in northern guinea savannah of Nigeria.