This document discusses the effects of different calcium levels in feed on the productive performance of laying hens. It reviews literature showing that calcium levels between 3.5-4.0% led to maximum egg production and egg mass, while levels of 3.6-4.2% resulted in the best feed conversion. Both inadequate and excess calcium intake decreased performance. Optimal shell quality and bone strength occurred at calcium levels of 3.0-4.2%. Sources of calcium discussed included limestone, oyster shell, and meat and bone meal.

1. Supervised by :

2. Effect of Calcium Level
on Productive
Performance of Laying
Hens

3. Introduction
Calcium is one of the most important compositions
of egg shell, it can significant affect performance and
egg shell quality of laying hens. (Narváez-Solarte et
al., 2006).
Egg shell quality and osteoporosis are permanent
and significant problems in egg production. In practice,
these problems are always associated with adequate
nutrition of layers with calcium (Lukić et al., 2011).

4. Inadequate Ca significantly
decreased egg production, egg weight,
egg shell thickness, feed consumption,
and bone density and strength (Roland
et al., 1996, Roberts and Blaney
2000). On the other hand excess Ca
significantly reduced egg weight, egg
production, and feed consumption
(Harms and Waldroup, 1971), and
reduced the profits. (Narváez-Solarte
et al., 2006).

5. Calcium is the mineral with the
highest concentration in the body of
poultry, consisting of 1.5% of its body
weight. It is more than one third of
total mineral body content of an adult
bird (Klasing, 1998) and represents
one third of eggshell components.(
Pelicia et al., 2011).

6. Calcium Requirements of Layers
The egg shell is composed primarily of calcium
carbonate. Since 97% of the eggshell consists of
calcium carbonate, Ca is an essential element for
eggshell formation and construction (Parsons &
Combs, 1981; Hunton, 1995). The pullet’s
requirement for calcium is relatively low during the
growing period, but when the first eggs are produced,
the need is increased at least four times, with
practically all of the increase being used for the
production of eggshells (Lukić et al., 2011).

7. There are many factors including strains, other
nutrients such as phosphorus and dietary energy,
age of birds, and temperature, which can affect Ca
requirement, (Narváez-Solarte et al., 2006).
A number of studies have been conducted to
investigate Ca requirement for laying hens as show
in table 1

8. Table 1. Published reports on calcium requirement of laying hens
Referenceg/h/d
Roush et al. (1986)4.73
Frost and Roland, Sr.
(1991)
4.53
Keshavarz and
Nakajima(1993)
5.17
Roland and Bryant(1994)4.35
NRC(1994)3.25
Roland et al. (1996)4.20Ahmad et al. (2003)

9. Calcium Sources for Laying Hens
There are different sources of calcium.
1. Limestone The most common source of calcium for
layer feeds is limestone is the principal
supplemental Ca source used in laying hen rations
due to its abundant natural reserves, low cost, and
easy incorporation into layer feeds. Different aspects
of shell quality were reported to be improved by the
partial replacement of limestone with oyster shells in
the diet (Hunton, 1995; 2005; Roberts, 2004).

10. 2.The use of oyster shell resulted in improved calcium
retention, and better shell quality as measured by egg
specific gravity, and several other criteria such as shell
thickness, percent shell, etc. Since oyster shell is
usually much more expensive than limestone, its use is
often limited (Roland Sr. 2000).

11. 3.Meat and bone meal (MBM) is an excellent dietary
source of protein, Ca and phosphorus (P) (Sell &
Jeffrey, 1996; Parsons et al., 1997; Shirley &
Parsons, 2001).

12. Results

13. Table 2. Effect of incremental calcium level change on egg production of
laying hen
AvgWeekly egg production (%)Calcium
level
%))
87654321
82.382.782.780.381.381.183.182.884.
4
5.00
79.175.875.877.579.480.081.582.580.
0
4.50
81.883.083.280.981.082.081.080.182.
1
4.00
80.181.581.580.678.478.579.479.681.
4
3.50
80.481.681.880.281.182.078.976.780.
5
3.00
75.
3
76.676.676.177.474.471.670.978.
7
2.50
1.601.851.852.192.142.162.162.330.5SEM
NS: Not significant at P > 0.05, **: P < 0.01
(2003).,Ahmad et al

14. Figure 2. Effect of Ca level on Egg production kg/hen
Castillo et al., (2004)

15. AvgWeekly egg weight (gm)Calcium
level
%))
87654321
64.1664.5463.8564.2864.1264.3
6
64.0363.9664.1
7
5.00
64.6765.2164.9564.3265.0964.0
2
64.9
0
65.1163.7
4
4.50
65.1165.2264.9465.1665.1165.1165.0365.1965.1
3
4.00
64.4664.8964.3564.4664.6264.6
4
64.5864.0564.1
2
3.50
64.5164.9064.8964.1264.8964.2
1
64.8264.264.2
6
3.00
64.1064.4864.0963.8764.6964.1
8
63.8
3
63.7263.9
2
2.50
0.170.180.240.200.220.230.190.170.27SEM
NSNSNSNSNSNS****NSSignificanc
Table 3. Effect of incremental calcium level change on
egg weight
NS: Not significant at P > 0.05, **: P < 0.01
(2003).,Ahmad et al

16. AvgWeekly feed consumption (gm)Calcium
level
%))
87654321
111.4111.3110.7110.
0
112.3111.7111.5110.9112.95.00
110.7109.5107.5110.
8
115.0111.2112.3110.5111.14.50
114.3113.9113.6113.
3
117.8117.0114.2112.4112.24.00
113.9116.2116.4115.
4
116.0116.2115.0107.8108.53.50
111.7114.1112.5111.7115.3113.9112.2108.6104.93.00
110.4113.2113.4112.
6
116.0112.8109.1103.2102.62.50
0.650.570.910.760.610.660.570.680.65SEM
NSNSNSNSNSNS******significance
Table 4. Effect of incremental calcium level change on feed
consumption
NS = Not significant at P > 0.05, ** = P < 0.01
(2003).,Ahmad et al

17. Castillo et al., (2004)
Figure 1. Effect of calcium level on feed conversion

18. Bone
strengt
h
Egg
shell
Weigh
t
(g)
(kg/c
m2)
Feed
Conversio
n
(g feed/g
egg)
Feed
Intake
(g/hen/ d)
Egg
mass
(g/hen
/d)
Egg
weight
(g)
Egg
production
(%)
Ca
%
8.276.862.367155.5549.5463.8777.592.60
10.426.862.206113.4351.9164.0581.033.00
12.206.972.161113.6153.1764.00
83.073.40
12.207.142.073112.3054.4166.0782.373.80
12.527.032.215112.1451.1063.8680.064.20
********NS*Probability
Table 5. Effect of calcium level on egg production, egg weight, egg mass,
feedconsumption, feed conversion, egg shell weight, and bone strength in
leghorn laying hens from 46 to 62 weeks of age
*P<0.05; * * (P<0.01)
et al., (2006)Narváez-Solarte

19. Figure 3 – Eggshell thickness (mm) of brown layers in their second production
cycle fed different calcium levels.
Pizzolante et al., (2011)

20. Table 7. Egg internal quality of semi-heavy layers in the second
production cycle fed diets containing different calcium and available
phosphorus levels.
Pelicia et al ., (2011)
Feed
conversion
ratio
Ca
intake
(%)
Feed
intake
(%)
Egg
mass
(%)
Egg
weight
%))
Lay
)%(
Ca level (%)
Kgdozen
2.3141.7443.98132.657.763.291.33.0
2.3351.7695.00133.457.563.590.63.75
2.3191.775521130.256.264.187.64.5
NSNSP<0.001
*
NSNSNSP<0.001*significance

21. Conclusions
1.Can be concluded that increasing dietary Ca from (2.5
- 4.5%) significantly improved performance of laying
hens (egg production, egg mass and egg thickness).
2.Dietary Ca level for maximum egg production and egg
mass, and the best feed conversion were (3.5-4.0),
(3.5-3.8) and (3.6-4.2)% respectively.

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