Phenotypic study of egg production curve in commercial broiler breeders using Compartmental function

Safari-Aliqiarloo, Abbas; Zare, Masoomeh; Faghih-Mohammadi, Farhang; Seidavi, Alireza; Laudadio, Vito; Selvaggi, Maria; Tufarelli, Vincenzo

doi:10.1590/rbz4720170225

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Non-Ruminants • R. Bras. Zootec. 47 • 2018 • https://doi.org/10.1590/rbz4720170225 copy

Phenotypic study of egg production curve in commercial broiler breeders using Compartmental function

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The objective of this study was to analyze the effect of environmental factors on egg production curve traits in broiler breeders. The weekly egg production records of birds collected from four different flocks were used to estimate the egg production curve parameters using the Compartmental function (y = A(1 − exp⁻^b⁽^t ⁻ ^d⁾)exp⁻^ct). The coefficient of determination (R²) obtained by the model was 0.98. Least squares analysis of variance indicated that the environmental factors such as hatchability and flock had significant effects on egg production curve traits. The highest correlation was observed between the weekly potential maximum yield and yield at the beginning of laying, whereas the lowest correlation was found between the weekly potential maximum production and production after peak yield. Associated factors with the increasing slope of egg production curves had a negative correlation with the decrease after peak. The correlation analysis showed that peak production had a negative and significant relationship with production towards peak and time to reach peak production, while there was a positive and significant correlation with the slope decrease after peak yield. The Compartmental function can be used as an alternative model to predict egg production traits in broiler breeders.

Key Words
equation; modeling; poultry

Parameter¹ 1 Modeled as: yt = a(1−exp−b(t − d))exp−ct, in which yt is the egg production on week t, a is the potential maximum weekly output of eggs, b and c are factors associated with the inclining and declining slope of the egg production curve, and d is the parameter representing yield at the beginning of egg laying.	Mean	Standard deviation
a	7.44	1.42
b	0.047	0.04
c	0.188	0.22
d	0.802	0.005
Y_max^* * Peak yield calculated as: [abc(c/b)]/ecd(b +c)(1+(c/b)).	5.12	0.98
T_max^ Time required to reach peak yield calculated as: (d+(1/b)ln[(b+c)/c]).	33.0	–
R²	0.989	–

Variable	Egg production curve trait¹ 1 Modeled as: yt = a(1−exp−b(t − d))exp−ct, in which yt is the egg production on week t, a is the potential maximum weekly output of eggs, b and c are factors associated with the inclining and declining slope of the egg production curve, and d is the parameter representing yield at the beginning of egg laying.				T_max² 2 Time required to reach peak yield calculated as: (d+(1/b)ln[(b+c)/c]).	Y_max³ 3 Peak yield calculated as: [abc(c/b)]/ecd(b+c)(1+(c/b)).
Variable	a	b	c	d
Flock (F)	72.90^ P<0.01.	1.88^ P<0.01.	0.013^ P<0.01.	0.87^ P<0.01.	169.70^ P<0.01.	83.20^ P<0.01.
Hatchability (H)	9.02ns	0.22ns	0.001ns	0.53^* * P<0.05.	18.29ns	13.43^ P<0.01.
H × F	16.60^* * P<0.05.	0.23ns	0.002^ P<0.01.	0.25^ P<0.01.	24.75^ P<0.01.	4.33^ P<0.01.
Residual	11.20	0.12	0.001	0.07	9.51	1.30

Variable	Egg production curve trait¹ 1 Modeled as: yt = a(1−exp−b(t − d))exp−ct, in which yt is the egg production on week t, a is the potential maximum weekly output of eggs, b and c are factors associated with the inclining and declining slope of the egg production curve, and d is the parameter representing yield at the beginning of egg laying.				T_max² 2 Time required to reach peak yield calculated as: (d+(1/b)ln[(b+c)/c]).	Y_max³ 3 Peak yield calculated as: [abc(c/b)]/ecd(b+c)(1+(c/b)).
Variable	a	b	c	d
Hatchability
1	8.42b	0.41	0.03d	1.4a	10.56a	5.19b
2	11.13a	0.38	0.039c	1.25c	9.18b	5.39a
3	9.04b	0.36	0.046b	1.22c	9.03b	4.57c
4	8.12b	0.39	0.051a	1.30b	8.36c	4.67c

Trait	Egg production curve trait¹ 1 Modeled as: yt = a(1−exp−b(t − d))exp−ct, in which yt is the egg production on week t, a is the potential maximum weekly output of eggs, b and c are factors associated with the inclining and declining slope of the egg production curve, and d is the parameter representing yield at the beginning of egg laying.			T_max² 2 Time required to reach peak yield calculated as: (d+(1/b)ln[(b+c)/c]).	Y_max³ 3 Peak yield calculated as: [abc(c/b)]/ecd(b+c)(1+(c/b)).
Trait	b	c	d
a	0.06^* * P<0.05.	−0.8ns	0.87^ P<0.01.	0.319^* * P<0.05.	0.24ns
b		0.185^ P<0.01.	0.03ns	0.38^ P<0.01.	−0.36^ P<0.01.
c			0.04^* * P<0.05.	0.51^* * P<0.05.	0.17^ P<0.01.
d				0.39ns	−0.19ns
T_max					−0.74^ P<0.01.

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[1] * Corresponding author: vincenzo.tufarelli@uniba.it