**3. Results**

For the initial experiment, a total of 477 eggs for hatching were incubated in two different time periods. When the parent flocks were 33 weeks old (YF33) and 49 weeks old (OF49), 252 eggs taken from the younger flock (YF33) and 225 eggs from the older flock (OF49) were incubated.

Regardless of the age and sex of the hatched chicks, total number of fertilized eggs was 452 (94.76%), nonfertilized 25 (5.24%), and there were 43 eggs with dead embryo (9.01% out of the number of eggs incubated; 9.51% out of the number of eggs fertilized), while the total number of hatched chicks was 409 (85.74% out of incubated eggs; 90.49% out of fertilized eggs).

In general, we can conclude that the younger flock (YF33) had higher incubation values than the older flock (OF49) as the fertilization rate was 95.24 and 94.22%,

**223**

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks…*

**Indicators** *¯x n* **<sup>S</sup>**x¯*<sup>S</sup>* **VC**

58.06 5.48 4.29 78.18 52.82 6.58 11.34 38.80 66.84

58.83 5.51 4.30 78.15 53.51 6.63 11.28 39.57 67.26

58.41 5.49 4.29 78.16 53.14 6.60 11.31 39.15 67.03

62.92 5.71 4.38 76.69 57.35 7.23 11.48 42.14 66.96

63.90 5.73 4.40 76,72 58.05 7.47 11.68 42.93 67,16

0.28 0.01 0.01 0.10 0.34 0.04 0.06 0.21 0.14

0.35 0.01 0.01 0.09 0.38 0.05 0.07 0.26 0.18

0.22 0.01 0.01 0.07 0.26 0.03 0.05 0.17 0.11

0.21 0.01 0.01 0.03 0.28 0.04 0.04 0.16 0.06

0.31 0.01 0.01 0.03 0.35 0.05 0.04 0.23 0,06

3.09 0.13 0.11 1.13 3.71 0.48 0.65 2.28 1.49

3.48 0.13 0.11 0.94 3.83 0.53 0.73 2.61 1.84

3.29 0.13 0.11 1.05 3.78 0.50 0.69 2.46 1.67

2.12 0.09 0.07 0.33 2.77 0.42 0.42 1.62 0.61

2.98 0.10 0.09 0.25 3.30 0.53 0.38 2.22 0,53

5.32 2.37 2.56 1.44 7.03 7.29 5.73 5.88 2.23

5.91 2.36 2.56 1.20 7.16 7.94 6.47 6.59 2.74

5.63 2.37 2.56 1.34 7.11 7.58 6.10 6.28 2.49

3.37 1.58 1.60 0.43 4.83 5.81 3.66 3.84 0.91

4.66 1.74 2.04 0.33 5.69 7.09 3.25 5.17 0,79

*DOI: http://dx.doi.org/10.5772/intechopen.89191*

**Young parent flock (YF33)**

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

**Female chicks**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

One day chick mass (g)

One day chick mass (g)

One day chick mass (g)

**Old parent flock (OF49)**

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

**Female chicks**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

One day chick mass (g)

One day chick mass (g)

**Male chicks**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

**Both sexes**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

**Male chicks**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks… DOI: http://dx.doi.org/10.5772/intechopen.89191*


*Animal Models in Medicine and Biology*

of the chicken in the egg mass).

(*S*), and variation coefficient (VC).

Yijk = μ + FAi + ESC + (FA × ESC)ij + eijk,

FAi—effect of *i*-flock age (YF33 and OF49);

ESCj—effect *ј*-egg sex-chick during incubation period;

including interaction.

μ—general mean;

eijk—accidental error.

the older flock (OF49) were incubated.

incubated eggs; 90.49% out of fertilized eggs).

where:

*k*-repetition;

**3. Results**

those eggs which hatched live and healthy chicken.

Before the eggs were laid into the incubator, following measurements were made: egg shape index and egg volume, absolute and relative egg mass loss until day 18 of incubation, and the percentage of the chicken in the egg mass (relative share

Egg shape index (ESI) was calculated according to the following formula: ESI = EW (egg width)/EL (egg length) × 100. Particular attention was given to

Egg volume was calculated according to the formula [34]: *V* = (π/6) × *L* × *W*<sup>2</sup> where *V* = egg volume; *W* = egg width, *L* = egg length; π = constant, 3.1416. When moved to the incubator hatching tray (day 18), eggs were individually placed in separate compartments in order to be sure which chicken was hatched from which egg. Based on the egg mass and the newly hatched chicken mass, relative share of the chicken in the egg mass was calculated, that is, chick percentage (CP) in the egg mass, according to the following formula: −CP = [(chick mass − CM)/(egg mass − EM) × 100]. Information obtained in this way was entered into a database designed by the statistical software IBM SPSS statistics Version 22 (2013). Basic data processing was conducted by applying the standard variation statistical methods (descriptive statistics): arithmetic mean (*x*¯), […] arithmetic mean error (S¯x), standard deviation

Difference in significance between observed morphometric traits was tested by application of the corresponding variance analysis (two-level factorial experiment—2 flock ages × 2 sexes) with uneven numbers of repetition per treatment—classes,

Yijk—observed morphometric value in *i-*flock age, of the *ј*-egg/chick sex, and

Based on the variance analysis and the results of the *F*exp. values, all significant and very significant differences were graded by Tukey test. Additionally, phenotype correlation coefficients (rp) between observed morphometric traits, primarily between the egg mass and egg shape index and other morphometric indicators, with stress on the chick's sex, were calculated according to the relevant formula.

For the initial experiment, a total of 477 eggs for hatching were incubated in two

Regardless of the age and sex of the hatched chicks, total number of fertilized eggs was 452 (94.76%), nonfertilized 25 (5.24%), and there were 43 eggs with dead embryo (9.01% out of the number of eggs incubated; 9.51% out of the number of eggs fertilized), while the total number of hatched chicks was 409 (85.74% out of

In general, we can conclude that the younger flock (YF33) had higher incubation values than the older flock (OF49) as the fertilization rate was 95.24 and 94.22%,

different time periods. When the parent flocks were 33 weeks old (YF33) and 49 weeks old (OF49), 252 eggs taken from the younger flock (YF33) and 225 eggs from

(FA × ESC)ij—effect of interaction between *i*-flock age and *ј*-chick sex;

Following is the mathematical model of the variance analysis:

**222**


#### **Table 1.**

*Mean values and variability of morphometric traits of eggs (chicks) which hatched chicks.*

respectively, chick hatchability percentage out of the number of incubated (laid) eggs was 86.51 and 84.89%, respectively, and 90.83 and 90.09% out of the number of fertilized eggs. Embryo mortality was 8.73 and 9.17% (YF33), while in the older flock (OF49), it was 9.33 and 9.91%.

Detailed measurements of morphometric indicators of eggs which hatched female and male chicks (the most important egg category) were made. Their mean values and absolute and relative variability measures are given in **Table 1**, and the difference significance is given in **Table 2**.

In the younger flock (YF33), average mass of eggs which hatched female chicks was 58.06 g, and 58.83 g was the mass of eggs which hatched male chicks (**Table 1**). Difference determined (−0.77 g) was not statistically confirmed

**225**

**Table 2.**

*(YF33 and OF49).*

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks…*

(P > 0.05). Correspondingly, in the older flock (OF49), the average mass of eggs which hatched female chicks was smaller by 0.98 g (**Tables 1** and **2**). The difference was not statistically significant (P > 0.05). In YF33, egg shape index which hatched female chicks was 78.18%, while of those which hatched male chicks, it was 78.15%, and the difference of 0.03 was not statistically significant (P > 0.05). In contrast to YF33, in OF49 eggs which hatched male chicks had higher egg shape index (76.69–76.72%), but the difference (−0.03%) was not significant (P > 0.05). Egg volume, both in YF33 and OF49, was greater in case of eggs which hatched male

; OF49 = 57.35 and 58.05 cm3

**Indicators (traits) Xž−Mxs Difference Significance** *t***exp.**

58.06−58.83 5.48−5.51 4.29−4.30 78.18−78.15 52.82−53.51 6.58−6.63 11.34−11.28 38.80−39.57 66.84−67.26

62.92−63.90 5.71−5.73 4.38−4.40 76.69−76.72 57.35−58.05 7.23−7.47 11.48−11.68 42.14−42.93 66.98−67.16

60.30−61.23 5.59−5.61 4.33−4.35 77.49−77.47 54.91−55.66 6.88−7.03 11.41−11.45 40.34−41.16 66.90−67.21

58.41−63.38 5.49−5.72 4.29−4.39 78.16−76.70 53.14−57.68 6.60−7.34 11.31−11.57 39.15−42.51 67.03−67.06

*Difference significance of mean values of some morphometric traits of eggs which hatched chicks* 

) were not statistically confirmed (P > 0.05).

−0.77 −0.03 −0.01 0.03 −0.69 −0.05 0.06 −0.77 −0.42

−0.98 −0.02 −0.02 −0.03 −0.70 −0.24 −0.20 −0.79 −0.18

−0.93 −0.02 −0.02 0.02 −0.75 −0.15 −0.06 −0.82 −0.31

−4.97 −0.23 −0.10 1.46 −4.54 −0.74 −0.26 −3.36 −0.03

), differences calculated

NS NS NS NS NS NS NS \* NS

NS NS NS NS NS \* \* \* NS

\* NS NS NS NS \* NS \*\* \*

\*\*\* \*\*\* \*\*\* \*\*\* \*\*\* \*\*\* \*\*\* \*\*\* NS

1.738 0.754 0.697 0.212 1.348 0.785 0.757 2.359 1.879

1.878 1.085 1.303 0.496 1.593 2.547 2.484 1.984 1.543

2.430 1.261 1.926 0.188 1.837 2.486 1.002 2.988 2.458

16.784 19.842 10.385 18.562 13.264 15.196 4.551 15.131 0.228

*DOI: http://dx.doi.org/10.5772/intechopen.89191*

chicks (YF33 = 52.82and 3.51 cm3

**Young parent flock (YF33) - sexes** Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

**Old parent flock (OF49) - sexes** Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

*\* means p<0.05; \*\* means p<0.01; \*\*\* means p<0.001.*

**Parent flock age, young – old (YF33 and OF49)**

**Young and old parent flock YF33 and OF49) - sexes**

and −0.70 cm3

(−0.69 cm3

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

One day chick mass (g)

One day chick mass (g)

One day chick mass (g)

One day chick mass (g)

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

## *Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks… DOI: http://dx.doi.org/10.5772/intechopen.89191*

(P > 0.05). Correspondingly, in the older flock (OF49), the average mass of eggs which hatched female chicks was smaller by 0.98 g (**Tables 1** and **2**). The difference was not statistically significant (P > 0.05). In YF33, egg shape index which hatched female chicks was 78.18%, while of those which hatched male chicks, it was 78.15%, and the difference of 0.03 was not statistically significant (P > 0.05). In contrast to YF33, in OF49 eggs which hatched male chicks had higher egg shape index (76.69–76.72%), but the difference (−0.03%) was not significant (P > 0.05). Egg volume, both in YF33 and OF49, was greater in case of eggs which hatched male chicks (YF33 = 52.82and 3.51 cm3 ; OF49 = 57.35 and 58.05 cm3 ), differences calculated (−0.69 cm3 and −0.70 cm3 ) were not statistically confirmed (P > 0.05).


#### **Table 2.**

*Difference significance of mean values of some morphometric traits of eggs which hatched chicks (YF33 and OF49).*

*Animal Models in Medicine and Biology*

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

Egg mass before incubation (g)

) Egg mass loss until day 18 of incubation (g) Egg mass loss until day 18 of incubation (%)

Relative chick share in the egg mass (%)

**Young and old parent flock(YF33 and OF49)**

**Both sexes**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

One day chick mass (g)

**Female chicks**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

One day chick mass (g)

One day chick mass (g)

One day chick mass (g)

**Male chicks**

**Both sexes**

**Table 1.**

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

Egg length (cm) Egg width (cm) Egg shape index (%) Egg volume (cm3

**224**

flock (OF49), it was 9.33 and 9.91%.

difference significance is given in **Table 2**.

respectively, chick hatchability percentage out of the number of incubated (laid) eggs was 86.51 and 84.89%, respectively, and 90.83 and 90.09% out of the number of fertilized eggs. Embryo mortality was 8.73 and 9.17% (YF33), while in the older

*Mean values and variability of morphometric traits of eggs (chicks) which hatched chicks.*

**Indicators** *¯x n* **<sup>S</sup>**x¯*<sup>S</sup>* **VC**

63.38 5.72 4.39 76.70 57.68 7.34 11.57 42.51 67.06

60.30 5.59 4.33 77.49 54.91 6.88 11.41 40.34 66.90

61.23 5.61 4.35 77.47 55.66 7.03 11.47 41.16 67.21

60.73 5.60 4.34 77.48 55.26 6.95 11.44 40.72 67.04

0.19 0.01 0.01 0.02 0.22 0.03 0.03 0.14 0.04

0.24 0.01 0.01 0.08 0.27 0.04 0.04 0.18 0.08

0.30 0.02 0.01 0.07 0.31 0.05 0.04 0.21 0.10

0.19 0.01 0.01 0.05 0.20 0.03 0.03 0.14 0.06 2.60 0.10 0.08 0.30 3.03 0.48 0.41 1.96 0.58

3.62 0.16 0.10 1.13 4.01 0.55 0.56 2.60 1.17

4.12 0.16 0.11 1.00 4.24 0.67 0.62 2.95 1.38

3.88 0.16 0.11 1.07 4.13 0.62 0.59 2.80 1.28

4.10 1.75 1.82 0.39 5.28 6.54 3.54 4.61 0.86

6.00 2.86 2.31 1.46 7.30 7.99 4.91 6.44 1.75

6.73 2.85 2.53 1.29 7.62 9.53 5.40 7.17 2.05

6.39 2.86 2.53 1.38 7.48 8.92 5.15 6.88 1.91

Detailed measurements of morphometric indicators of eggs which hatched female and male chicks (the most important egg category) were made. Their mean values and absolute and relative variability measures are given in **Table 1**, and the

In the younger flock (YF33), average mass of eggs which hatched female chicks was 58.06 g, and 58.83 g was the mass of eggs which hatched male chicks (**Table 1**). Difference determined (−0.77 g) was not statistically confirmed


#### **Table 3.**

*Phenotype correlation coefficients between egg mass of both flocks (YF33 and OF49) and egg shape index.*

In both age groups, female chicks had smaller mass (YF33 = 38.80–39.57 g; OF49 = 42.14–42.93 g), and determined differences were statistically relevant: P < 0.05 and P < 0.01, respectively. Relative share of the chick in the egg mass in both flocks was also greater in case of male chicks, but these differences were not statistically significant (P > 0.05). Regardless of the parent flock age, eggs which hatched female chicks had lower values of the observed morphometric traits, except for the egg shape index (77.49 − 77.47%), which was higher by 0.02% in eggs which hatched female chicks, but the difference determined was not statistically significant (P > 0.05).

Contrary to the chick's sex, parent flock's age had more significant effects on observed morphometric traits of both sexes (**Tables 1** and **2**). All observed morphometric indicators of both eggs and newly hatched chicks of both sexes were statistically considerably higher (P < 0.001) in OF49 than in the younger flock YF33, except the relative chicken share in the egg mass, whereby the relative chicken share was also greater in OF49; however, the obtained difference (−0.03%) was not statistically significant (P > 0.05). Egg shape index was higher in case of YF33 (78.16 − 76.70%), and the determined difference of 1.46% was statistically significant (P < 0.001).

Among all observed morphometric traits, the phenotype correlation (*r*p) was calculated between the egg mass before the incubation period and the egg shape index as the most relevant indicator for the purpose of this study. Calculated values for both flocks and both sexes are given in **Table 3**.

There was a very weak, weak, and medium phenotype correlation between the egg mass before incubation and the egg shape index, and the correlation coefficients were statistically confirmed (P < 0.01; P < 0.001), except between the egg mass of those eggs which hatched female chicks and the egg shaped index in the younger flock YF33, whereby the calculated coefficient (*r*xy = 0.107) was not statistically confirmed (P > 0.05). Apart from the mentioned strength of the phenotype correlation, total correlation on the global level was found between the egg mass before incubation and the mass of the newly hatched chicks, that is, the correlation coefficient values were above 0.900.

## **4. Discussion**

It is an established fact that the egg laying intensity grows with the age of the parent flock, that is, the rate of the egg fertilization and the chick hatchability grows

**227**

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks…*

tions are more prominent in case of eggs which hatched male chicks.

while the percentage of fertilized eggs and chick hatchability decreases.

mass and also on the share of the chicken in the egg mass.

egg mass up to day 18 of incubation varied from 12.1 to 13.7%.

of Cobb hybrid of 44 weeks of age, when the embryo mortality rate recorded was over 12%. Comparably, Ulmer-Franco et al. [8] report that the age of broiler parents of the Cobb 500 hybrids and egg mass have influence on incubation values of eggs for fertilization. With flock's growing age—from week 29 to week 59, egg mass increased from 53.8 to 71.3 g, relative egg mass loss until day 18 of incubation decreased from 12.8 to 11.9%, egg fertilization rate increased from 76.7 to 94.4%, while the chick hatchability out of the number of fertilized eggs decreased from 88.0 to 87.0%. Total embryo mortality was 10.6% (29 weeks old flock) and 9.4% (59 weeks old flock). Also in the Cobb 500 parent flock, 500 [1, 11] report statistically significant (P < 0.001) effect of age on the egg mass and newly hatched chicken mass increase, while the largest number of fertilized eggs was observed in the middle of the production cycle (97.05%), followed by the beginning of the cycle (96.09%), and the smallest was recorded in the final stage of the production cycle (93%). The chick hatchability out of the number of incubated and the number of fertilized eggs was also at its peak in the middle of the production cycle and amounted to 81.14 and 83.94%, respectively. Alsobayel et al. [12] report that the genotype (Arbor Acres, Cobb, and Ross) and the age of the broiler parents (30–35, 40–45, 50–55 weeks) have effects on the average egg mass and one-day chicken

up to a certain flock age, after which point it decreases. Most of the morphometric indicators (egg mass and newly hatched chicken mass in the first place) normally grow throughout the whole production cycle, which was confirmed by our study and the studies of numerous other authors who treated this matter. These fluctua-

Abudabos [9] in two broiler parent flocks (Cobb and Ross) and in parent flocks of different ages (26, 44, 32, and 36 weeks of age) report that the egg mass, relative egg mass loss until day 19 of incubation, newly hatched chicken mass, and the share (percentage) of the chick in the egg mass grow with the age in both parent flocks,

Embryo mortality is higher in case of older broiler parents, particularly in case

Depending on the type of hybrid (genotype), egg mass fluctuated between 63.7 and 64.7 g, one-day-old chicken mass between 44.5 and 45.4 g, and the share of chicken in the egg mass varied from 68.1 to 69.7%. In all three hybrids, the growth of egg mass (59.3–68.9 g) and chick mass (41.4–48.4 g) simultaneously with the growth of the flock's age was recorded, while the share of the chick in the egg mass was largest in the last weeks (69.7%) and smallest in the middle of the production cycle (687%). Similar chicken share in the egg mass in 10 different broiler hybrid parents—breeds (between 66.9 and 70.4%) is reported by [7]. Furthermore, loss of

Pinchasov [3] makes a slightly different conclusion compared with previously mentioned researchers, which is that effects of laying hens age are less significant for the chick mass than the egg mass which has a considerably greater effect on the one-day-old chick mass. In line with these conclusions, [5] point out that physical characteristics of eggs (egg mass, egg shell thickness and porosity, egg shape index) play an important role in the embryo development process and hatchability success rate. Effects of egg mass on the newly hatched chicken mass, embryo mortality, and percentage of the chicken in the egg mass (progression of the egg mass loss during incubation period) are reported by [6] in case of the hybrid Ross SL 2000 parent flock, raised from 35 to 49 weeks of age. Light eggs (average mass 54.59 g) hatched chicken of 38.11 g of average mass, medium eggs (58.89 g) hatched the chicks of 40.74 g, and heavy eggs (63.10 g) hatched the chicks of 43.18 g of average mass. Loss due to embryo mortality was greater in light (7.83%) and heavy eggs (7.90%), in comparison with eggs of medium weight (6.67%). Furthermore, heavy (large) eggs

*DOI: http://dx.doi.org/10.5772/intechopen.89191*

#### *Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks… DOI: http://dx.doi.org/10.5772/intechopen.89191*

up to a certain flock age, after which point it decreases. Most of the morphometric indicators (egg mass and newly hatched chicken mass in the first place) normally grow throughout the whole production cycle, which was confirmed by our study and the studies of numerous other authors who treated this matter. These fluctuations are more prominent in case of eggs which hatched male chicks.

Abudabos [9] in two broiler parent flocks (Cobb and Ross) and in parent flocks of different ages (26, 44, 32, and 36 weeks of age) report that the egg mass, relative egg mass loss until day 19 of incubation, newly hatched chicken mass, and the share (percentage) of the chick in the egg mass grow with the age in both parent flocks, while the percentage of fertilized eggs and chick hatchability decreases.

Embryo mortality is higher in case of older broiler parents, particularly in case of Cobb hybrid of 44 weeks of age, when the embryo mortality rate recorded was over 12%. Comparably, Ulmer-Franco et al. [8] report that the age of broiler parents of the Cobb 500 hybrids and egg mass have influence on incubation values of eggs for fertilization. With flock's growing age—from week 29 to week 59, egg mass increased from 53.8 to 71.3 g, relative egg mass loss until day 18 of incubation decreased from 12.8 to 11.9%, egg fertilization rate increased from 76.7 to 94.4%, while the chick hatchability out of the number of fertilized eggs decreased from 88.0 to 87.0%. Total embryo mortality was 10.6% (29 weeks old flock) and 9.4% (59 weeks old flock). Also in the Cobb 500 parent flock, 500 [1, 11] report statistically significant (P < 0.001) effect of age on the egg mass and newly hatched chicken mass increase, while the largest number of fertilized eggs was observed in the middle of the production cycle (97.05%), followed by the beginning of the cycle (96.09%), and the smallest was recorded in the final stage of the production cycle (93%). The chick hatchability out of the number of incubated and the number of fertilized eggs was also at its peak in the middle of the production cycle and amounted to 81.14 and 83.94%, respectively. Alsobayel et al. [12] report that the genotype (Arbor Acres, Cobb, and Ross) and the age of the broiler parents (30–35, 40–45, 50–55 weeks) have effects on the average egg mass and one-day chicken mass and also on the share of the chicken in the egg mass.

Depending on the type of hybrid (genotype), egg mass fluctuated between 63.7 and 64.7 g, one-day-old chicken mass between 44.5 and 45.4 g, and the share of chicken in the egg mass varied from 68.1 to 69.7%. In all three hybrids, the growth of egg mass (59.3–68.9 g) and chick mass (41.4–48.4 g) simultaneously with the growth of the flock's age was recorded, while the share of the chick in the egg mass was largest in the last weeks (69.7%) and smallest in the middle of the production cycle (687%). Similar chicken share in the egg mass in 10 different broiler hybrid parents—breeds (between 66.9 and 70.4%) is reported by [7]. Furthermore, loss of egg mass up to day 18 of incubation varied from 12.1 to 13.7%.

Pinchasov [3] makes a slightly different conclusion compared with previously mentioned researchers, which is that effects of laying hens age are less significant for the chick mass than the egg mass which has a considerably greater effect on the one-day-old chick mass. In line with these conclusions, [5] point out that physical characteristics of eggs (egg mass, egg shell thickness and porosity, egg shape index) play an important role in the embryo development process and hatchability success rate. Effects of egg mass on the newly hatched chicken mass, embryo mortality, and percentage of the chicken in the egg mass (progression of the egg mass loss during incubation period) are reported by [6] in case of the hybrid Ross SL 2000 parent flock, raised from 35 to 49 weeks of age. Light eggs (average mass 54.59 g) hatched chicken of 38.11 g of average mass, medium eggs (58.89 g) hatched the chicks of 40.74 g, and heavy eggs (63.10 g) hatched the chicks of 43.18 g of average mass. Loss due to embryo mortality was greater in light (7.83%) and heavy eggs (7.90%), in comparison with eggs of medium weight (6.67%). Furthermore, heavy (large) eggs

*Animal Models in Medicine and Biology*

Total eggs which hatched either sex

*\*\* means p<0.01; \*\*\* means p<0.001.*

chick

**Table 3.**

Eggs which hatched female chicks YF33

Eggs which hatched male chicks YF33

In both age groups, female chicks had smaller mass (YF33 = 38.80–39.57 g; OF49 = 42.14–42.93 g), and determined differences were statistically relevant: P < 0.05 and P < 0.01, respectively. Relative share of the chick in the egg mass in both flocks was also greater in case of male chicks, but these differences were not statistically significant (P > 0.05). Regardless of the parent flock age, eggs which hatched female chicks had lower values of the observed morphometric traits, except for the egg shape index (77.49 − 77.47%), which was higher by 0.02% in eggs which hatched female chicks, but the difference determined was not statistically significant (P > 0.05). Contrary to the chick's sex, parent flock's age had more significant effects on observed morphometric traits of both sexes (**Tables 1** and **2**). All observed morphometric indicators of both eggs and newly hatched chicks of both sexes were statistically considerably higher (P < 0.001) in OF49 than in the younger flock YF33, except the relative chicken share in the egg mass, whereby the relative chicken share was also greater in OF49; however, the obtained difference (−0.03%) was not statistically significant (P > 0.05). Egg shape index was higher in case of YF33 (78.16 − 76.70%), and the determined difference of 1.46% was statistically significant (P < 0.001). Among all observed morphometric traits, the phenotype correlation (*r*p) was calculated between the egg mass before the incubation period and the egg shape index as the most relevant indicator for the purpose of this study. Calculated values

**Eggs—chick sex Flock age** *n r***xy Correlation** 

118 101

100 90

0.261\*\* 0.430\*\*\*

0.107NS 0.498\*\*\*

YF33 + OF49 409 −0.314\*\*\* Weak

OF49

OF49

*Phenotype correlation coefficients between egg mass of both flocks (YF33 and OF49) and egg shape index.*

Total eggs which hatched YF33 218 0.188\*\* Very weak either sex chick OF49 191 0.442\*\*\* Medium Eggs which hatched female chicks YF33 + OF49 219 −0.286\*\*\* Weak Eggs which hatched male chicks YF33 + OF49 190 −0.353\*\*\* Weak

**significance**

Weak Medium

Very weak Medium

There was a very weak, weak, and medium phenotype correlation between the

It is an established fact that the egg laying intensity grows with the age of the parent flock, that is, the rate of the egg fertilization and the chick hatchability grows

egg mass before incubation and the egg shape index, and the correlation coefficients were statistically confirmed (P < 0.01; P < 0.001), except between the egg mass of those eggs which hatched female chicks and the egg shaped index in the younger flock YF33, whereby the calculated coefficient (*r*xy = 0.107) was not statistically confirmed (P > 0.05). Apart from the mentioned strength of the phenotype correlation, total correlation on the global level was found between the egg mass before incubation and the mass of the newly hatched chicks, that is, the correlation

for both flocks and both sexes are given in **Table 3**.

coefficient values were above 0.900.

**226**

**4. Discussion**

had the greatest egg mass loss during incubation period. i.e., the smallest eggs had the largest share of the chick mass in the egg mass (69.81%), followed by the eggs of medium weight (69.17%), while the largest eggs had the smallest share (68.43%). Wilson [4, 6, 10] report the relative share of the chick mass in the egg mass fluctuating from 67 to 70%, from 62 to 76%, and from 68.43 to 69.81%, respectively. Similar conclusions related to effects of age and the egg weight group on incubation values in the Hubbard Classic broiler parents were made by [13, 14]. In the light egg weight group (average mass 63.09 g), average mass of newly hatched male chicks was 43.33 g; in the medium weight group (68.85 g), it was 48.40 g; and in the heavy weight group (74.81 g), it was 52.36 g. In case of female chicken, the average mass was 43.29, 48.24, and 52.38 g, respectively. The relative share of the chicken mass in the egg mass was 69.97, 70.22, and 70.38% (male chicks), and 69.84, 70.12, and 70.17% (female chicks).

In an interesting research, [5, 15] indicate considerable effects of the egg shape index on incubation indicators and point out that eggs of anomalous shape should not be used for incubation because they prevent normal embryo development which results in a higher embryo mortality rate during incubation period. This conclusion was confirmed by [16] who studied mechanical (physical) and incubation values of eggs of two hen breeds (Naked Neck and Sombor kaporka) raised in semi-intensive keeping system. They report egg shape index of 71.01 and 72.04%, respectively, for the two breeds and 73.61 and 76.68% for the relative share of the chicken in the egg mass. Abanikannda and Leigh [17] report higher egg shape index of eggs which hatched male chicks (Anak and Marshall hybrids) than in eggs which hatched female chicks (75.25 and 74.53%; 76.27 and 76.00%). Regarding the eggs coming from the Ross hybrid, egg shape index was 76.09% (male chicks) and 76.41% (female chicks).

Based on presented and discussed results of cited authors, we can conclude that most of them studied or reported effects of nongenetic factors on incubation values and morphometric egg indicators and production of one-day-old chicken of both sexes of different genotypes (hybrids) of broiler parents. This is understandable because hybrids of both sexes are used for the broiler meat production. However, when it comes to light hybrids egg incubation, male chicks are killed, while females are used for breeding and raising, i.e., for the commercial production of eggs for consummation.

Kocevski et al. [25, 26] studied effects of age on the mass, strength, fertility, and hatchability of eggs in two light line hybrids (ISA Brown and DeKalb White) on production of eggs for consummation and for fertilization.

Egg mass was considerably affected (P ≤ 0.05) by age, but not by the line (genotype), although eggs of the (commercial) ISA Brown line were somewhat heavier than those of the DeKalb White line. The heaviest egg mass was that of older poultry, while eggs laid by younger hens had smaller mass. In younger commercial laying hens and parent […] flocks laying hens produced eggs with stronger shells than those laid by older hens. Average chicken hatchability during the 6 months period of egg production was 70.50% (Isa Brown) and 73.64% (DeCalb). Zita et al. [29] report egg mass to grow with hen's age in three genotypes (ISA Brown, Hisex Brown, and Moravia BSL), while the egg shape index decreased.

Average egg mass of the ISA Brown laying hens was 54.00 g at the beginning of the production cycle, 62.78 g in the middle, and 63.42 g at the end of the production cycle (54–60 weeks of age), while the egg shape index decreased from 78.52 to 76.64%, and 75.09%. Duman et al. [30] are of opinion that the standard egg shape index of commercial laying hens fluctuates between 72.2 and 75.9% (average value −74.3%), of the pointy shape between 68.0 and 71.9% (average 71.0%), while the egg shape index of round eggs ranged from 76.1 to 82.3% (average 78.8%).

**229**

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks…*

Furthermore, the authors make a conclusion that the egg shape index affects certain consummation egg qualities and report certain phenotype correlation between

Results obtained in our research partly correspond with conclusions of previous authors who primarily studied different genotypes of broiler parents. Research most similar to ours was conducted by [27] with one of the aims to determine chick's potential sex before egg incubation (Super Nick White Layer) using morphometric measurements of eggs (weight, length, width, shape index, volume). Their conclusion is that length, width, shape index, and volume before incubation period have certain effect on the future chick sex, especially egg shape index and egg width and length. In case of 54 weeks old laying hens, egg shape index was 71.1% (male), 75.5% (female), and 75.3% (both sexes), while the average egg mass was 60.8 g (male), 60.9 g (female), and 60.8 g (both sexes). Two-hundred forty-four (244) chicks of both sexes were hatched out of 300 incubated eggs (the hatchability rate was 81.33%). Terčič and Pestotnik [28] recorded egg incubation values of the hybrid Prelux-G parent younger (24 weeks) and older (65 weeks) flocks. Older parent flock produced heavier eggs (66.63−56.77 g), than the younger one, had higher relative egg mass loss up to week 18 of incubation (11.26−11.14%), male and female chicks were heavier, embryo mortality was higher (13.52−11.36%), while the chick hatchability out of the number of incubated and fertilized eggs was at a lower level. Male-female chick rate was 1.09 in the younger flock and 1.16 in the older flock. In both flocks, male chicks were slightly heavier than the female. In general, our results are to a large extent compatible with results obtained by [27, 28] and even [24]. Narushin [24] reports an average egg shape index of 75.20% (69.70−80.10%)

(52.00−70.40 cm3

These results agree with those of [23] who reports the egg length of 5.90 cm, width 4.40 cm, and egg shape index around 75.0%. Additionally, [31–33] analyzed morphometric indicators of the wild birds' eggs with a purpose to determine possible bird sex before the incubation period and reached similar but questionable

Certain authors report phenotype correlation between the parent flock's age in hens and even other types of poultry, laying intensity, hatching egg mass, newly hatched offspring mass, and the relative share of the chick in the egg mass. Skewea et al. [2] point out that the egg mass increases with the age of the parent flock in domestic birds and also that eggs of different sizes (mass) have different physical (external) and chemical (internal) characteristics which affect the hatchability percentage out of the number of fertilized eggs and the quality of hatched chicks. Explicitly, one-day-old chick mass is tightly related with the preincubation egg mass, that is, there is a strong correlation between them. Furthermore, heavier chicks have smaller yolk, while lighter chicks have a larger yolk (food reserve), which enables them to survive a longer period of time before they can obtain

In line with these results, Suarez et al. [35] report total correlation between the age and the egg mass of Arbor Acres broiler parents of 29–57 weeks of age and medium phenotype correlation between the age and chick mass, and the determined correlation coefficient was statistically significant at P < 0.001. Farooq et al. [36] report statistically significant (P < 0.05) correlation coefficient (*r*p = 0.496) between the egg mass and one-day chick mass of the pure breed Rhode Island Red. By calculating the phenotype correlation coefficients between the egg mass, chick mass, and the hatchability percentage out of the number of incubated and fertilized eggs, these authors have also confirmed statistically significant correlation

(P < 0.05), which is to a large extent in line with our results.

) of eggs laid by the 65-week-old

*DOI: http://dx.doi.org/10.5772/intechopen.89191*

these qualities.

and egg volume of 60.19 cm3

exogenous food source.

results.

Hy-Line Brown hens, regardless of the chick sex.

*Effects of Morphometric Indicators on Incubation Values of Eggs and Sex of the Chicks… DOI: http://dx.doi.org/10.5772/intechopen.89191*

Furthermore, the authors make a conclusion that the egg shape index affects certain consummation egg qualities and report certain phenotype correlation between these qualities.

Results obtained in our research partly correspond with conclusions of previous authors who primarily studied different genotypes of broiler parents. Research most similar to ours was conducted by [27] with one of the aims to determine chick's potential sex before egg incubation (Super Nick White Layer) using morphometric measurements of eggs (weight, length, width, shape index, volume). Their conclusion is that length, width, shape index, and volume before incubation period have certain effect on the future chick sex, especially egg shape index and egg width and length.

In case of 54 weeks old laying hens, egg shape index was 71.1% (male), 75.5% (female), and 75.3% (both sexes), while the average egg mass was 60.8 g (male), 60.9 g (female), and 60.8 g (both sexes). Two-hundred forty-four (244) chicks of both sexes were hatched out of 300 incubated eggs (the hatchability rate was 81.33%). Terčič and Pestotnik [28] recorded egg incubation values of the hybrid Prelux-G parent younger (24 weeks) and older (65 weeks) flocks. Older parent flock produced heavier eggs (66.63−56.77 g), than the younger one, had higher relative egg mass loss up to week 18 of incubation (11.26−11.14%), male and female chicks were heavier, embryo mortality was higher (13.52−11.36%), while the chick hatchability out of the number of incubated and fertilized eggs was at a lower level. Male-female chick rate was 1.09 in the younger flock and 1.16 in the older flock. In both flocks, male chicks were slightly heavier than the female. In general, our results are to a large extent compatible with results obtained by [27, 28] and even [24]. Narushin [24] reports an average egg shape index of 75.20% (69.70−80.10%) and egg volume of 60.19 cm3 (52.00−70.40 cm3 ) of eggs laid by the 65-week-old Hy-Line Brown hens, regardless of the chick sex.

These results agree with those of [23] who reports the egg length of 5.90 cm, width 4.40 cm, and egg shape index around 75.0%. Additionally, [31–33] analyzed morphometric indicators of the wild birds' eggs with a purpose to determine possible bird sex before the incubation period and reached similar but questionable results.

Certain authors report phenotype correlation between the parent flock's age in hens and even other types of poultry, laying intensity, hatching egg mass, newly hatched offspring mass, and the relative share of the chick in the egg mass. Skewea et al. [2] point out that the egg mass increases with the age of the parent flock in domestic birds and also that eggs of different sizes (mass) have different physical (external) and chemical (internal) characteristics which affect the hatchability percentage out of the number of fertilized eggs and the quality of hatched chicks. Explicitly, one-day-old chick mass is tightly related with the preincubation egg mass, that is, there is a strong correlation between them. Furthermore, heavier chicks have smaller yolk, while lighter chicks have a larger yolk (food reserve), which enables them to survive a longer period of time before they can obtain exogenous food source.

In line with these results, Suarez et al. [35] report total correlation between the age and the egg mass of Arbor Acres broiler parents of 29–57 weeks of age and medium phenotype correlation between the age and chick mass, and the determined correlation coefficient was statistically significant at P < 0.001. Farooq et al. [36] report statistically significant (P < 0.05) correlation coefficient (*r*p = 0.496) between the egg mass and one-day chick mass of the pure breed Rhode Island Red. By calculating the phenotype correlation coefficients between the egg mass, chick mass, and the hatchability percentage out of the number of incubated and fertilized eggs, these authors have also confirmed statistically significant correlation (P < 0.05), which is to a large extent in line with our results.

*Animal Models in Medicine and Biology*

70.17% (female chicks).

76.41% (female chicks).

consummation.

had the greatest egg mass loss during incubation period. i.e., the smallest eggs had the largest share of the chick mass in the egg mass (69.81%), followed by the eggs of medium weight (69.17%), while the largest eggs had the smallest share (68.43%). Wilson [4, 6, 10] report the relative share of the chick mass in the egg mass fluctuating from 67 to 70%, from 62 to 76%, and from 68.43 to 69.81%, respectively. Similar conclusions related to effects of age and the egg weight group on incubation values in the Hubbard Classic broiler parents were made by [13, 14]. In the light egg weight group (average mass 63.09 g), average mass of newly hatched male chicks was 43.33 g; in the medium weight group (68.85 g), it was 48.40 g; and in the heavy weight group (74.81 g), it was 52.36 g. In case of female chicken, the average mass was 43.29, 48.24, and 52.38 g, respectively. The relative share of the chicken mass in the egg mass was 69.97, 70.22, and 70.38% (male chicks), and 69.84, 70.12, and

In an interesting research, [5, 15] indicate considerable effects of the egg shape index on incubation indicators and point out that eggs of anomalous shape should not be used for incubation because they prevent normal embryo development which results in a higher embryo mortality rate during incubation period. This conclusion was confirmed by [16] who studied mechanical (physical) and incubation values of eggs of two hen breeds (Naked Neck and Sombor kaporka) raised in semi-intensive keeping system. They report egg shape index of 71.01 and 72.04%, respectively, for the two breeds and 73.61 and 76.68% for the relative share of the chicken in the egg mass. Abanikannda and Leigh [17] report higher egg shape index of eggs which hatched male chicks (Anak and Marshall hybrids) than in eggs which hatched female chicks (75.25 and 74.53%; 76.27 and 76.00%). Regarding the eggs coming from the Ross hybrid, egg shape index was 76.09% (male chicks) and

Based on presented and discussed results of cited authors, we can conclude that most of them studied or reported effects of nongenetic factors on incubation values and morphometric egg indicators and production of one-day-old chicken of both sexes of different genotypes (hybrids) of broiler parents. This is understandable because hybrids of both sexes are used for the broiler meat production. However, when it comes to light hybrids egg incubation, male chicks are killed, while females are used for breeding and raising, i.e., for the commercial production of eggs for

Kocevski et al. [25, 26] studied effects of age on the mass, strength, fertility, and hatchability of eggs in two light line hybrids (ISA Brown and DeKalb White) on

Egg mass was considerably affected (P ≤ 0.05) by age, but not by the line (genotype), although eggs of the (commercial) ISA Brown line were somewhat heavier than those of the DeKalb White line. The heaviest egg mass was that of older poultry, while eggs laid by younger hens had smaller mass. In younger commercial laying hens and parent […] flocks laying hens produced eggs with stronger shells than those laid by older hens. Average chicken hatchability during the 6 months period of egg production was 70.50% (Isa Brown) and 73.64% (DeCalb). Zita et al. [29] report egg mass to grow with hen's age in three genotypes (ISA Brown, Hisex

Average egg mass of the ISA Brown laying hens was 54.00 g at the beginning of the production cycle, 62.78 g in the middle, and 63.42 g at the end of the production cycle (54–60 weeks of age), while the egg shape index decreased from 78.52 to 76.64%, and 75.09%. Duman et al. [30] are of opinion that the standard egg shape index of commercial laying hens fluctuates between 72.2 and 75.9% (average value −74.3%), of the pointy shape between 68.0 and 71.9% (average 71.0%), while the egg shape index of round eggs ranged from 76.1 to 82.3% (average 78.8%).

production of eggs for consummation and for fertilization.

Brown, and Moravia BSL), while the egg shape index decreased.

**228**

In both ethical and economic contexts, as an addition to this discussion, we are including here the studies of [18, 19], who used male chicks of the ISA Brown and Hy-Line hybrids in organic production of broiler meat, where the fattening period lasted 49 and 90 days, and 51 days, and obtained quality organic broiler meat. Gerken et al. [20–22] point out that from the humane and welfare aspect, it is not economically justified to use male chicks of all light line hybrids for fattening in intensive broiler meat production, but in extensive and semiextensive conditions, with a prolonged fattening period, it is possible to produce good-quality meat with higher protein content and lower percent of abdominal fat. Finally, Weissmann et al. [22] report greater average mass of newly hatched male chicks, than of female chicks by 0.5, 2.1, and 0.02 g in three parent flocks of the light type Lohmann—Germany.
