BOVAN BROWN BIRDS | POULTRY AND RESEARCH UNIT OF THE DEPARTMENT OF ANIMAL SCIENCE

Materials and Methods

Experimental Site

          The study was carried out at the Poultry And Research Unit Of The Department Of Animal Science, Faculty of Agriculture and Natural Resources Management, Ebonyi State University, Abakaliki. The study lasted for a period of four weeks (28 days).

Experimental Animals

          Bovan Brown birds raised on battery cage system at different stages of production were used for the experiment. The birds were served with commercial layer’s mash that contained 16% crude protein and 2,500 kilocal/kg of energy. Clean drinking water was also given, regular medication and vaccination was also carried out during the period. The stages at which the eggs were collected were 30 weeks, 52 weeks and 72 weeks of age.

Experimental Procedures.

          Seventy eight (78) newly laid eggs were collected at each stage of production from the birds used for the study, making a total of two hundred and thirty six eggs for the three stages of production. Six eggs were selected at random from each stage of production (eighteen eggs for the three stages) to determine the internal and external egg quality. The remaining two hundred and sixteen eggs were numbered and randomly allotted into three experimental groups of seventy two eggs each (twenty four eggs from each stage of production).The experimental groups were randomly allocated to the following storage methods: room temperature at 23⁰ ,refrigerator at 5⁰c and air tight box at 30cm depth. The eggs were stored using different storage method for each duration apart from day one. The storage periods were seven days, fourteen days, twenty one days and twenty-eight days.

Data Collection

          The eggs were numbered and weighed with sensitive balance immediately after collection from the pen to get the initial weight. The internal and external quality of the eggs at each stage of production were taken periodically at 7 days interval for a total of 28 days. The external quality data that were measured were;

(a)      Egg weight (g)

(b)     Egg length (cm)

(c)      Egg width (cm)

(d)     Egg shell weight (g)

(e)      Egg shell thickness (mm)

(f)      Egg shape index (%)

          The internal quality also measured such as

(a)      Albumen weight (g)

(b)     Albumen height (mm)

(c)      Albumen width (cm)

(d)     Yolk weight (g)

(e)      Yolk height (mm)

(f)      Yolk width (cm)

(g)     Haugh unit (%)

(h)     Yolk pH

(1)     Albumen pH

          The egg weight, shell weight, albumen weight, yolk weight were measured using a sensitive scale balance (Mahler P1210). Shell thickness were measured at different points of the broad end, middle portion and narrow end using a micrometer screw gauge. The egg shape index was estimated using the following formular (egg shape index = width of egg/length of the egg x 100%). The egg width, egg length, albumen width, Albumen height, yolk width and yolk height were measured using a vernier caliper. The albumen pH and yolk pH was determined using pH meter. The Haugh units were estimated according to the formula

Hu     =        100 log (h+7.51-1.7w^0.37)^{2 .}Where  

Hu     =        Haugh unit

H       =        Observable height of the albumen (mm)

W      =        Weight of egg (g) (COtta, 1997)

Data Analysis

          Data obtained on internal and external egg qualities measured were subjected to descriptive statistics so as to obtain the means and the standard error or their means. A one-way analysis of variance (ANOVA) were used to determine the effect of age, duration and storage methods on the internal and external egg quality. Significant means were separated using Duncan’s New multiple Range Test (DNMRT) according to Obi (2002). SPSS (2009) statistical package were used for the statistical analysis.

          The statistical model adopted were;

Yij               =        m + ai + ∑_ij

Where Yij    =        Observation of the ith duration and jth storage method

on egg quality

m                  =       Sample mean for the parameters being considered

ai                 =       random effect of ith duration on jth storage

I                  =        fresh egg (first day), 7 days, 14 days, 21days, 28 days

J        =        Room temperature, refrigerator and air tight box.

∑ij     =        Experimental error.

RESULTS

EFFECT OF STORAGE METHODS ON THE EGG QUALITY TRAITS

          The result of the effect of storage method on the egg quality traits is presented in the table 1.

TABLE 1: EFFECT OF STORAGE METHODS ON THE EGG QUALITY TRAITS

^abcd means on the same row followed by different superscript are significantly different (P<0.05); SEM:- Standard Error of the means.

The effect of storage method on the egg quality traits were found to be significant at (P<0.05) for all internal quality traits considered. The mean of fresh eggs were significantly different from the eggs in the airtight box, room temperature and refrigerator. The albumen height, albumen pH and Haugh unit of refrigerated and fresh eggs were not significantly different (P>0.05). It was observed that refrigerated eggs were able to retain their albumen height, albumen pH and Haugh unit like that of fresh eggs.

Effect of holding period on the egg quality traits

The result of the effect of holding period on the egg quality traits is presented in the table 2.

TABLE 2: EFFECT OF HOLDING PERIOD ON THE EGG QUALITY TRAITS

^abcd means on the same row followed by different superscripts are significantly different (P<0.05); SEM standard Error of the means.

          The effect of holding period on the egg quality traits were found to be significant (P<0.05). Albumen height, albumen width, yolk height, yolk width and yolk pH were significantly different from the fresh egg. The albumen height and yolk height consistently decreased over increased holding period. In addition, the albumen width, yolk width and yolk pH increased over increase in holding period. However, albumen weight, albumen pH, yolk weight and Haugh unit showed little or no significant difference (P>0.05).

EFFECT OF AGE OF THE BIRDS ON THE EGG QUALITY TRAITS

The result of the effect of age of the birds on the egg quality traits is presented in the table 3.

TABLE 3: EFFECT OF AGE OF THE BIRDS ON THE EGG QUALITY TRAITS

^abc means on the same row followed by different superscripts are significantly different, SEM:- Standard Error of the means.

          The effect of age of the birds on the egg quality traits were found to be significant at (p<0.05) It was found that egg weight, egg length, egg width, shell weight, albumen weight, albumen width and yolk weight increased with increase in hen’s age. The egg shape index, albumen pH, yolk pH, yolk height showed little significant difference. The egg shell thickness albumen height and yolk width showed no significant difference while the Haugh unit decreased with increase age of the hens.