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Effect of Dietary Phosphorus Level and Source on Productive Performance and Egg Quality of Two Commercial Strains of Laying Hens1,2
Effect of Dietary Phosphorus Level and Source on Productive Performance and Egg Quality of Two Commercial Strains of Laying Hens1'2 N. W. SAID and T. W. SULLIVAN3 Department of Animal Science, University of Nebraska, Lincoln, Nebraska 68583-0820 M. L. SUNDE and H. R. BIRD Department of Poultry Science, University of Wisconsin, Madison, Wisconsin 53706
ABSTRACT An experiment was conducted to study the influence of dietary total phosphorus (TP) level and source on the performance of two strains of commercial layers for two consecutive production years (26 to 68 and 76 to 116 weeks of age, respectively). Diet 1 contained .4% TP; Diets 2, 3 and 4 contained .5, .6, and .7% TP with supplemental P from dicalcium phosphate (DCP); Diets 5 and 6 contained .5 and .6% TP, respectively, with supplemental P from a sample of raw rock phosphate (RRP-1); Diets 7 and 8 contained .5 and .6% TP, respectively, with supplemental P from a second sample of raw rock phosphate (RRP-2). Calcium level was 2.75% in all diets, and crushed oyster shell provided ad libitum to all birds increased the total calcium to about 3.00%. Diet 1 was inferior to the average of all supplemented diets relative to feed consumption rate (P<.005) and egg weight (P<.005) during the first year. Diet 1 was also inferior relative to egg production rate (P<.01), feed consumption rate (P<.005), and egg weight (P<.005) during the second year, whereas it was superior in shell quality (P<.05) during the first year. Increasing TP from DCP resulted in a significant linear increase in feed consumption (P<.05), feed conversion ratio, and Haugh units (P<.005). Increasing TP from DCP also resulted in a significant linear decrease in shell quality (P<.05) and significant linear and quadratic decreases in egg weight (P<.005) during the first year. During the second year, increasing TP from DCP resulted in a significant linear decrease in egg production rate (P<.005) and feed efficiency but significant linear (P<.01) and quadratic (P<.05) increases in feed consumption, and significant linear and quadratic increases (P<.005) in Haugh units. Hens receiving RRP diets responded differently during the first and second years. The DCP supported greater egg weight than the RRP during the second year and permitted better feed conversion during both years. Strain A produced larger eggs than Strain B regardless of treatment (P<.005). When egg production rate and most other response criteria were considered, .5% TP with DCP as the supplemental source gave the best results in both production years. A TP of .6% from RRP-2 gave similar results in both years. (Key words: phosphorus level, source, laying chickens, two strains) 1984 Poultry Science 63:2007-2019 INTRODUCTION The phosphorus requirement of laying hens is still a major concern in the poultry industry. This concern is primarily one of economics, since the cost of feed grade phosphate has greatly increased following the 1973 to 1974 energy crisis that led to a shortage of feed phosphate supplements. Nutritionists reacted to the problem of a feed phosphate shortage by attempting to
1 Published as Paper Number 7113, Journal Series, Nebraska Agricultural Experiment Station. 2 From a dissertation submitted by the senior author in partial fulfillment of requirements for the Ph.D. degree. 3 To whom correspondence should be addressed.
define more accurately minimum phosphorus requirements and by evaluating alternate and less expensive sources of phosphorus. However, when considering the phosphorus requirements of layers, one cannot ignore differences in availability among phosphorus sources and possible differences among various genetic strains as to minimum phosphorus requirement. Possible differences in the phosphorus requirement of hens or differences in the ability of birds to utilize phosphorus from different sources have been reported (Charles et al., 1978; Tennessee Random Sample Studies, 1973; Francis, 1957; Ingram et al., 1976). Few experiments have been conducted during the last 10 years as to the use of raw rock phosphate (RRP) as a supplement for
2007
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(Received for publication March 14, 1983)
2008
SAID ET AL.
MATERIALS AND METHODS
Nine hundred sixty White Leghorn-type hens 26 weeks of age were housed at the rate of 3 birds per cage measuring 45.7 x 30.5 cm. There were 480 birds from each of two commercial strains, DeKalb and Hisex, which were designated A and B, respectively. The experiment was conducted at the Arlington Poultry Research Farm, University of Wisconsin, Madison. The study was initiated October 14, 1977. Thirty hens of either strain were assigned randomly to 10 consecutive cages sharing a common feeder; this housing arrangement allowed 32 experimental units in total. Water was supplied ad libitum by a Hart cup in each cage of 3 birds. Eight dietary treatments were then randomly assigned to the 32 experimental units. A
treatment group consisted of four experimental units that included two replicates of each strain (a total of 120 birds). The experimental diets are presented in Table 1. The basal ration (Diet 1) was formulated to contain .4% TP. Diets 2, 3, and 4 were formulated to contain .5, .6 and .7% TP, respectively, using DCP to replace appropriate quantities of corn and limestone in the basal ration. Diets 5 and 6 were formulated to contain .5 and .6% TP, respectively, using raw rock phosphate (RRP-1). Diets 7 and 8 were formulated to contain .5 and .6% TP, respectively, using a second sample of raw rock phosphate (RRP-2). The two RRP used in Diets 5 through 8 replaced appropriate amounts of corn and ground limestone in the basal ration. Ingredient levels, calculated composition, and laboratory analysis of the eight diets are presented in Table 1. Fluorine content was found to be 3.60 and 3.67% in RRP-1 and RRP-2, respectively. All birds were weighed, beak-trimmed, treated with nicotine sulfate solution (applied to feathers around the vent), and vaccinated for fowl cholera prior to assignment to cages. The appropriate experimental diets were supplied ad libtum. Birds received 14 hr of light daily during both production years. Egg production was recorded daily for each replicate. The percent hen-day average egg production, mortality, and feed consumption were calculated for each replicate of 30 birds every 28 days. Feed efficiency was calculated and expressed in kilograms of feed consumed per dozen eggs produced. Eggs from 3 consecutive days of production within each month were collected from each replicate to obtain egg weight data. Shell quality was measured every 8 weeks beginning at 44 weeks of age and onward using the Marius apparatus under a stress of 500 g on the vertical axis. The same eggs were also used to determine interior quality by measuring the Haugh unit index. At 68 weeks of age, all hens were weighed and force-molted (details of the force-molting procedures have been described by Said et al., unpublished data). After the molt, hens were maintained in the same cages and continued on the same experimental diets for an additional experimental period of 40 weeks. Therefore, treatment effects during the first year could have been continued into the second year or 40 weeks. Data concerning feed consumption, feed efficiency, mortality, average percent hen-day egg production, interior quality, and shell
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chickens, possibly due to poor results in earlier studies. Many factors were apparently involved in the disappointing results with feeding highfluorine rock phosphates in the early studies. Animal feed formulas are now more complete and provide a better nutrient balance than in the 1940's. One specific difference in layer feeds has been the use of lower levels of supplemental phosphorus. For this reason it could be possible that high fluorine phosphate supplements might be safer to use now than in the past. This idea was tested by using different levels of RRP in starting, growing, and laying diets (Said et al, 1979). Results of this study clearly demonstrated that RRP (3.6% fluorine) at .6 and 1.2% could be used in such diets without any deterimental effects on performance of layers during the first and second years of production. Charles et al. (1978) reported that .7% total phosphorus (TP) including supplements of either dicalcium phosphate (DCP) or RRP appeared to provide adequate phosphorus for hens during five 28-day periods. They reported no significant differences in percent egg production, feed consumption rate, feed efficiency, or eggshell quality between hens fed the two different phosphorus sources. The experiment reported herein was conducted primarily to study the response of caged, White Leghorn-type hens to different levels and sources of phosphorus during the first and second years of production under commercial conditions. Two commercial strains of hens were involved in the study.
.404
.507
2.74
2.76 .602
2.75
14.98 2871
100.00
100.00
100.00
100.00
100.00
15.00 2880
.50 .50
.50 .50
.50 .50
.50 .50
270
.504
2.74
2.74 .70
15.03 2888
14.97 2864
.75
.50 .50
69.95 16.60 3.30 2.00 6.40
.95
5
.50
Diets
69.25 16.60 3.30 2.00 6.45 1.40
4
69.45 16.60 3.30 2.00 6.70
3
69.70 16.60 3.30 2.00 6.90
69.90 16.60 3.30 2.00 7.20
2
15.02 2886
1
2
6
1 Supplied the following per kilogram of diet: gallomycin, .022 g; vitamin A, 4000 IU; vitamin D 3 , 1000 ICU: riboflavi nine, .5 g. 2 Additional calcium was provided in the form of oyster shell to all birds (ad libitum) to make the total calcium about
Lab analysis: Total phosphorus, % Fluorine, ppm
Calculated composition: Crude protein, % Metabolizable energy, kcal/kg Calcium, %2
Ground yellow corn Soybean meal (44%) Dehydrated alfalfa (17%) Meat meal (50%) Limestone Dicalcium phosphate Raw rock phosphate-1 Raw rock phosphate-2 Iodized salt Vitamin-mineral premix 1 Total
Ingredients
TABLE 1. Composition of experimental diets and laboratory analyses
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SAID ET AL.
2010
RESULTS AND DISCUSSION Hen-Day Egg Production. The effects of strain, phosphorus source, and level on average percent hen-day production are presented in Tables 3 and 4. Figure 1 shows the strain X diet interaction relative to average hen-day egg production of hens during the second year. This
interaction was apparently due to both levels of dietary phosphorus and source. When DCP was the source of supplemental phosphorus, maximum production by either strain was reached when the diet contained .5% TP. In contrast, when either RRP-1 or RRP-2 was the source of supplemental phosphorus, maximum egg production by either strain occurred only when the diet contained .6% TP, indicating that phosphorus was less available to the hens from RRP as compared to DCP. Although no significant strain effect on average egg production was evident during the first year of production, differences occurred between the two strains during the second year (Tables 3 and 4). Those Strain A hens that received .5% TP from RRP-1 had higher henday egg production than hens receiving .5%TP from RRP-2. However, birds receiving .6% TP from RRP-1 had a much lower rate of egg production as compared with hens fed .6% TP from RRP-2 (Figure 1). At the same time, increasing dietary phosphorus from .5 to .6% TP from RRP-1 resulted in a slight increase in egg production of Strain A. In contrast, the inclusion of .1% more phosphorus from RRP-2 resulted in a dramatic increase in egg production rate. Orthogonal contrast comparisons showed that during the first year feeding the unsup-
TABLE 2. General linear models procedure, split-plot design (whole plot CRD)
Sources of variation
Formula
Degrees of freedom
Factor A "strain" (whole plot) error a replicate within strain Factor B "Trt" 2 Strain X Trt interaction error b Total
a-1 a(w-l)1 b-1 (a-D(b-l) by subtraction awb—1
1 2 7 7 14 31
Orthogonal contrasts Basal diet vs. others Dicalcium phosphate level linear Dicalcium phosphate level quadratic R R P - 1 3 level linear R R P - 2 level linear R R P - 1 vs. R R P - 2 Dical vs. RRP Total 1
Where w = number of experimental units per level of factor A.
2
Trt = Treatment.
3
RRP-1 First sample of raw rock phosphate; RRP-2 = second sample of raw rock phosphate.
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quality were determined as described previously. Before the experiment was terminated, hens were weighed and three birds from each replicate (12 hens/treatment) were selected at random and sacrificed by cervical dislocation. Right tibiae were excised and cleaned of adhering tissues. Percent ash was determined for the dry, fat-free' bones. Samples of tibia ash were then assayed for fluoride content using the Technicon autoanalyzer (Technicon Instrumentation Corporation, Ardsley, NY). Productive performance and egg quality data from each year were analyzed by the Statistical Analysis System (SAS) by Barr et al. (1979). The general linear models procedure for split plots (where strain was considered as complete randomized whole plot and the treatment as the split plot) are presented in Table 2. Orthogonal polynomial and least squares mean comparisons were performed.
1
2 3 4
5 6
7 8
Basal
DCP 3 DCP DCP
RRP-1 RRP-1
RRP-2 RRP-2
RRP
NS NS NS NS NS NS NS
71.8 a b 71.7 a b 70.2b 74.0 a
.5 .6
.5 .6
74.0 a 75.2 a 71.7 a b
69.6t>
.5 .6 .7
.4
% TP
NS NS NS NS NS
*** *
107* m a b 118 c 116 c 112abc 116 c 114 b 116bc
115 113 NS
73.0 71.6 NS 2
3.36 3.48 3.42 3.48
.570 .696
3.33 3.54 3.57
3.21
3.45 3.39
.560 .696
.555 .708 .812
.428
.632 .622
Daily consumption (g/her /day; TP 1 Ca
*+*
NS
** * • **
NS
***
NS
1.95c 1.88 b
1.89b 1.97c
1.81 a 1.90 b 1.97c
1.91 b
1.92 1.91 NS
(kg/doz)
DCP = Dicalcium phosphate, RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
NS = Nonsignificant.
TP = Total phosphorus.
***P<.005.
*'P<.01.
2.6 2.5
2.6 2.6
2.4 2.6 2.7
2.6
2.7 2.6
(kg
Feed/eggs
' ' ' ' Means followed by different superscripts within the same column are significantly different (P<.05).
*P<.05.
3
2
1
ji h r fl p
DCPDS.
Effect Basal vs. others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2
Diet
p Supplement
Strain A Strain B
(g/hen/ day)
Feed consumption
(%)
Hen-day egg production
TABLE 3. Effect of strain and phosphorus (P) source and level on performance of he
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7 8
RRP-2 RRP-2
,e
100 b
96a
10lb 100 b
48.7 c d 51.0 C
47.9 d 55.2°
* *** * ***
NS
** ***
NS
*** ** * ***
100b 104 c 103 c
57.6 a 56.4 a b 53.2t>c
** ***
96*
50.0 C
99 101 NS 2
51.1 53.9
.505 .600
.480 .600
.500 .624 .721
.384
.544 .555
TP1
3.03 3.00
2.88 3.00
3.00 3.12 3.09
2.88
2.97 3.03
Ca
Daily consumption (g/hen/day)
(kg/doz)
** *
NS
** ***
NS
***
NS
2.60 e 2.22 b
2.45 e 2.37 d
2.09 2.2lb 2.32 c d
a
2.29 c
2.34 2.30
DCP = Dicalcium phosphate, RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
NS = Nonsignificant.
***P<.005.
**P<.01.
hen
3.3 2.8
3.2 3.0
2.7 2.8 3.0
3.0
2.9 3.0
(kg
Feed/eggs
Means followed by different superscripts within the same column are significantly different (P<.05).
.5 .6
.5 .6
.5 .6 .7
.4
%TP
TP = Total phosphorus.
' ' '
c
*P<.05.
3
2
1
a
Effect Basal vs . others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2 DCP vs. R R P
5 6
RRP-1 RRP-1
DCP DCP
DCP
2 3 4
1
Basal
3
Diet
Supplement
Strain A Strain B
(g/hen/ day)
Feed consump-
<%)
Hen-day egg production
TABLE 4. Effect of strain and phosphorus (P) source and level on performance'of
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PHOSPHORUS AND EGG QUALITY
P-.
.6
Strain A Strain B -I .7
DIETARY TOTAL PHOSPHORUS, %
FIG. 1. Strain X diet interaction (P<.05) as to average hen-day egg production, second year. DCP= Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
plemented diet (#1) did not result in a significant decrease (.05
phorus did not result in a significant increase in egg production rate during either year (Tables 3 and 4). On the contrary, Diet 4, which contained .7% TP, was associated with a lower rate of egg production as compared with Diets 2 or 3, which contained .5 and .6% TP., respectively. A comparison of the two RRP as to the effect on egg production revealed that RRP-2 was significantly better (P<.05) than RRP-1 as a phosphorus source for force-molted hens. Such differences did not exist during the first year of production. The performance of hens fed the RRP diets indicate that RRP could be used successfully as a source of phosphorus for layers. These results agree with previous findings in our laboratory (Said et al., 1979) even though hens in the present study were housed in cages, whereas in the earlier study hens were maintained in floor pens. Feed Consumption. Data in Tables 3 and 4 show no significant differences between Strain A and B in feed consumption throughout the entire experiment. Hens receiving the unsupplemented diet (#1) consumed significantly less feed (P<.005) as compared to the average feed consumption of hens receiving diets supplemented with inorganic phosphorus. These results do not agree with the findings of Ademosun and Kalango (1973), who reported phosphorus levels did not affect feed intake of laying hens. However, Summers et al. (1976) reported that feed intake was depressed only when the available phosphorus (AP) was reduced to .15% (inorganic phosphorus). Our results support the finding of Summers et al. (1976) and Hurwitz and Bornstein (1963). However, our data disagree with the results of Hamilton and Sibbald (1977) who reported variation in dietary phosphorus levels had no significant effect on either feed consumption or feed efficiency. It should be noted, however, that the lowest phosphorus level used by Hamilton and Sibbald (1977) was .45% AP (.60% TP), which is certainly well above the minimum requirement. Birds fed diets supplemented with DCP consumed comparable amounts of feed as hens fed the RRP diets (Table 3) during the first year of production. However, a highly significant difference (P<.005) existed during the second year; birds that received the RRP diets consumed less feed than those fed the DCP diets. The higher egg production rate of hens receiving DCP and the possible accumulative
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_
2013
2014
SAID ET AL.
rates of production. Egg Shell Quality as Measured by Deformation. Data presented in Tables 3 and 4 show the effect of strain, level, and source of phosphorus on egg shell quality. No significant differences (.05
63 -1
58-
d
/
BASAL
.
strain A Strain B
57-
'.' tlh .4
r— .5
~i .6
1 .7
DIETARY TOTAL PHOSPHORUS, %
FIG. 2. Strain X diet interaction (P<.005) as to average egg weight, first year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
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effect of fluorine from RRP diets might explain these differences. Feed Conversion. When DCP was the source of supplemental phosphorus, both strains showed maximum efficiency of feed conversion with .5% TP. Increasing the phosphorus to .6 and .7% TP resulted in a linear increase in the amount of feed required to produce a dozen eggs (Tables 3 and 4). An opposite trend was found when RRP-2 was the source of phosphorus. This trend in feed conversion can be explained simply by the fact that hens fed .6% TP from RRP-2 (Diet 8 produced significantly more (P<.05) eggs as compared to hens receiving .5% TP from RRP-2 (Diet 7), although both groups consumed nearly comparable amounts of feed (Tables 3 and 4). No significant differences (,05
PHOSPHORUS AND EGG QUALITY
A... ^ - ^ . O
/
RRP-1
«s-
• - - O DCP
-—Strain B
BASAL
DIETARY TOTAL PHOSPHORUS,
FIG. 3. Strain X diet interaction (P<.005) as to average egg weight, second year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
units in eggs collected either from Strain A or B (Fig. 4). While in contrast, increasing the total phosphorus level from RRP-1 seemed to steadily lower the interior quality of eggs collected from either strain. There seems to be no apparent explanation for the dramatic differences in the interior quality of eggs collected from hens fed the two different RRP. One can only speculate that RRP-1 may have possibly contained certain trace elements such
as vanadium, which could have decreased albumin quality (Berg et al., 1963) and consequently decreased Haugh units. When the interior quality of eggs collected from hens receiving the basal diet was compared to the average Haugh units of eggs collected from all other treatments, no significant differences were found. Phosphorus from DCP, RRP-1, and RRP-2 showed significant linear effects as to Haugh unit values of eggs collected during the first and second year of production (Tables 3 and 4). A highly significant difference was found between RRP-1 and RRP-2 as to the effect on Haugh unit values during the 2 years of production. Although those hens fed the RRP diets produced eggs with significantly higher interior quality (P<.005) during the first year as compared with those fed the DCP, these differences seemed to diminish as the hens progressed in age (Table 4). Hamilton and Sibbald (1977) reported a highly significant effect of strain (P<.005) on Haugh unit values at different periods of their experiment. A less profound effect of strain on Haugh unit values was found in the present study (Tables 3 and 4) and favored Strain A over Strain B. Survival Rate. Percent survival data of hens given the various dietary treatments are presented in Table 5. All groups exhibited very high survival rates throughout the first and second years of production. The overall mortality during the force molt period (35 days) was 4.2%. This mortality was apparently not influenced by dietary phosphorus treatments
BASAL
"•--• —
•S'-
.4
T
~\— .6
Strain B
-I .7
DIETARY TOTAL PHOSPHORUS, I
FIG. 4. Strain X diet interaction (P<.01) as to interior quality of eggs (Haugh units), first year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
•4
.5
.6
DIETARY TOTAL PHOSPHORUS, %
FIG. 5. Strain X diet interaction (P<.005) as to interior quality of eggs (Haugh units), second year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1 and second (RRP-2) sample.
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.Strain A —
a
2015
99.4 98.3 98.2 99.1
+ 173 + 229 + 211 + 144
1 7 5 9 + 173 1795 + 176 1 7 5 4 ± 169 1740 ± 180
1586 ± 1 8 0 1566 ± 179
1543 ± 185 1596 ± 183
5 6
7 8
RRP-1 RRP-1
RRP-2 RRP-2
2
1
99.0 98.4 98.4
+ 184 + 240 + 222
1783 ± 155 1 8 3 9 ± 181 1823 ± 191
1599 + 2 0 1 1599 ± 194 1601 + 191
.5 .6 .7
TP = Total phosphorus; DCP = dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2)
Values are means ± standard deviations from the means.
.5 .6
.5 .6
99.3
+ 106
1 6 7 0 ± 143
1564 ± 192
.4
1
2 3 4
98.9 98.6
(%)
DCP DCP DCP
+ 245 + 132
(g) 1 8 9 8 ± 175 1643 ± 173
1653 ± 192 1511 ± 144
Survival after 1 yr
Basal
TP2
Diet
Supplemental
Strain A: Strain B:
Body weight change
Body weight after 1 y r
Initial body weight
TABLE 5. Average body weights, body weight changes, and survival during the first and seco
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PHOSPHORUS AND EGG QUALITY
Table 5. Dietary phosphorus level apparently affected body weight gain, because those hens receiving the basal diet (.4% TP) gained the least body weight at the end of first year. Increasing dietary phosphorus from DCP resulted in a steady increase in body weight with the maximum at .6% TP for both years. The same trend was evident when RRP-1 was the source of phosphorus. The reverse was true when RRP-2 was the source, as birds receiving .5% TP from RRP-2 gained a little more weight as compared to those receiving .6% TP from the same source. The different responses to dietary RRP may be related to the fluorine content or availability of these samples. The RRP-2 contained a slightly higher level of fluorine than RRP-1 (Table 1). Also, the two RRP could have
TABLE 6. Influence of strain and phosphorus source and level on percent bone ash and fluoride content of ash, (end of second year)
Bone ash
Strain A: Strain B; Supplemental P Basal DCP DCP DCP
Diet
TP
Fluoride in ash
(%)
(ppm)
58.76 58.17 NS
4648 4022
***
2
55.42 c ab
1702 d 1477 d 1552 d 1466 d
RRP-1 RRP-1
59.23 61.87 a 61.12 a 57 7 2 b c 58.13 b
5472 c 9219 a
RRP-2 RRP-2
57.15 b c 57.07 b c
6802 b 6990°
Probabilities of significance1
Effect Basal vs. others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2 DCP vs. RRP
** * NS NS NS NS NS
NS NS
***
NS
***
' ' ' ' Means followed by different superscripts within the same column are significantly different (P<.05). 1
NS = Nonsignificant.
2
TP = Total phosphorus; DCP = dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second ' (RRP-2) sample. *P<.05. ***P<.005.
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of the first year. No significant differences ( 0 5 < P < . 1 0 ) in survival were found among different dietary phosphorus levels or sources. Survival data presented in Table 5 for the second year reflect only mortality that occurred in the 280-day postmolt experimental period. Strain had no significant effect on the survival rate of hens. These findings were in agreement with those of Hamilton and Sibbald (1977). Body Weight Gain. The maximum average difference in the initial body weight among the various treatment groups (58 g) was quite small. The average initial body weight of Strain A was 152 g greater than for Strain B. The average body weights and changes in body weight at the end of the first and second years are shown in
2017
2018
SAID ET AL.
feed/hen per day during the first year of production, which is in total agreement with the National Research Council (1977) recommendation. However, when the RRP furnished the supplemental phosphorus, the level of phosphorus needed for optimum performance during the first year was .6% TP. During the second year, the optimum performance of hens was again reached when their diet contained .5% TP from DCP or .6% TP from the two RRP. However, the birds consumed less feed during the second year as compared to the first year. On the basis of actual phosphorus requirement in terms of mg/hen per day, our data indicate that the laying hen required about 550 mg of total phosphorus per day during the first year of production for optimum performance, whereas the requirement was about 500 mg TP per hen per day during the second year of production for optimum performance. Mean daily consumptions of TP and calcium in g/hen per day for hens receiving each treatment are presented in Tables 3 and 4. The data also clearly indicate that RRP were of lower biological availability as compared to DCP but could be used successfully in layer rations if slightly higher levels are fed. This was especially true for RRP-2. Consideration should be given to fluorine when higher levels of RRP are used. Strain of bird influenced egg weight during the first year of production (Table 3) and also egg weight, egg production rate, feed con-
.423 .43
.5
.6
DIETARY T O T A L PHOSPHORUS. %
FIG. 6. Dosage response curve for dicalcium phosphate illustrating the method of calculating biological availability of phosphorus from the RRP relative to DCP. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
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differed as to contents of other toxic trace elements. Bone Ash Percent. The influence of phosphorus level, source, and strain on the percent bone ash is shown by data presented in Table 6. When compared with the average values of hens fed the supplemented diets, birds that received the basal diet had a s i g n i f i c a n t l y lower (P<.005) percent bone ash, indicating the marginal TP level in this diet (#1). Increasing phosphorus in the diet resulted in a numerical increase in bone ash percent, but the increase was not significant (.05
PHOSPHORUS AND EGG QUALITY
REFERENCES Ademosun, A. A., and I. O. Kalango, 1973. Effect of calcium and phosphorus levels on the performance of layers in Nigeria. 1. Egg production eggshell quality, feed intake and body weight. Poultry Sci. 52:1383-1392. Anderson, J. O., J. S. Hurst, D. C. Strong, H. Nielsen, D. A. Greenwood, W. Robinson, J. L. Shupe, W. Binns, R. A. Bagley, and C. I. Draper, 1955. Effect of feeding various levels of sodium fluoride for growing turkeys. Poultry Sci. 34:1147— 1152. Arscott, G. H., P. Rachapaetaryakom, P. E. Bernier, and F. W. Adams, 1962. Influence of ascorbic acid, calcium, and phosphorus on specific gravity of eggs. Poultry Sci. 41:485-488. Barr, A. J., J. H. Goodnight, J. P. Sail, W. H. Blair, and D. M. Chilko, 1979. SAS User's Guide, 1979 ed. J. T. Helwig and K. A. Council, ed. SAS Inst., Inc., Raleigh, NC. Berg, L. R., G. E. Bearse, and L. H. Merrill, 1963. Vanadium toxicity in laying hens. Poultry Sci. 42.1407-1411. Bletner, J. K., and G. C. McGhee, 1975. The effect of phosphorus on egg specific gravity and other production parameters. Poultry Sci. 54:1736. (Abstr.) Charles, O. W., S. Duke, and B. Reddy, 1978. Effect of phosphorus source and level on laying hen performance under varying temperature conditions. Pages 74 to 87 in Proc. 1978 Georgia Nutr.
Conf. Edwards, H. M., Jr., and F. A. Suso, 1981. Phosphorus requirement of six strains of caged laying hens. Poultry Sci. 60:2346-2348. Francis, D. W., 1957. Strain differences in the incidence of cage layer fatigue. Poultry Sci. 36: 181-183. Guenter, W., 1980. Dietary phosphorus and laying hen performance. Poultry Sci. 59:1615. (Abstr.) Haman, K., P. H. Phillips, and J. G. Halpin, 1936.The distribution and storage of fluoride in the tissues of the laying hen. Poultry Sci. 15:154-157. Hamilton, R.M.G., and I. R. Sibbald, 1977. The effects of dietary phosphorus on productive performance and egg quality of ten strains of WhiteJLeghorns. Poultry Sci^56:1221-1228. Holder, D. P., 1981. Dietary phosphorus requirements of force-molted Leghorn hens. Poultry Sci. 60:433-437. Hurwitz, S., and S. Bornstein, 1963. The effect of calcium and phosphorus in the diet of laying hens on egg production and shell quality. Isr. J. Agric. Res. 13:147-154. Ingram, R. F., J. K. Bletner, and G. McGhee, 1976. The response of four strains of Single Comb White Leghorn layers to two levels of dietary phosphorus. Poultry Sci. 55:2077. (Abstr.) Mostert, G. C , and L. G. Swart, 1968. Ca and P in laying rations for hens. S. Afr. J. Agric. Sci. 11:687-695. National Research Council, 1977. Nutrient Requirements of Poultry. 7th rev. ed. Natl. Acad. Sci., Washington, DC. Said, N. W., M. L. Sunde, H. R. Bird, and J. W. Suttie, 1979. Raw rock phosphates as a phosphorus supplement for growing pullets and layers. Poultry Sci. 58:1557-1565. Salman, A. J., and J. McGinnis, 1968. Availability of phosphorus from plant origin for layers. Poultry Sci. 47:1712-1713. Saville, P. D., 1967. Water fluoridation: Effect on bone fragility and skeletal calcium content in the rat. J. Nutr. 91:353-357. Summers, J. D., R. Grandhi, and S. Leeson, 1976. Calcium and phosphorus requirements of laying hens. Poultry Sci. 55:402-412. Tennessee Random Sample Laying Test (16th), 1973. Univ. Tennessee, Knoxville, TN.
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version, and interior quality of the eggs during the second year of production (Table 4). Among the factors that should be considered in determining the hen's phosphorus requirement are: strain of bird, bioavailability and composition of the phosphorus source, and conditions of the experiment. These factors should be indicated and emphasized to clarify some of the controversy relating to the dietary phosphorus requirement of layers. Strain of bird, bioavailability of P sources, and experimental conditions were clearly specified in the present study.
2019
ABSTRACT An experiment was conducted to study the influence of dietary total phosphorus (TP) level and source on the performance of two strains of commercial layers for two consecutive production years (26 to 68 and 76 to 116 weeks of age, respectively). Diet 1 contained .4% TP; Diets 2, 3 and 4 contained .5, .6, and .7% TP with supplemental P from dicalcium phosphate (DCP); Diets 5 and 6 contained .5 and .6% TP, respectively, with supplemental P from a sample of raw rock phosphate (RRP-1); Diets 7 and 8 contained .5 and .6% TP, respectively, with supplemental P from a second sample of raw rock phosphate (RRP-2). Calcium level was 2.75% in all diets, and crushed oyster shell provided ad libitum to all birds increased the total calcium to about 3.00%. Diet 1 was inferior to the average of all supplemented diets relative to feed consumption rate (P<.005) and egg weight (P<.005) during the first year. Diet 1 was also inferior relative to egg production rate (P<.01), feed consumption rate (P<.005), and egg weight (P<.005) during the second year, whereas it was superior in shell quality (P<.05) during the first year. Increasing TP from DCP resulted in a significant linear increase in feed consumption (P<.05), feed conversion ratio, and Haugh units (P<.005). Increasing TP from DCP also resulted in a significant linear decrease in shell quality (P<.05) and significant linear and quadratic decreases in egg weight (P<.005) during the first year. During the second year, increasing TP from DCP resulted in a significant linear decrease in egg production rate (P<.005) and feed efficiency but significant linear (P<.01) and quadratic (P<.05) increases in feed consumption, and significant linear and quadratic increases (P<.005) in Haugh units. Hens receiving RRP diets responded differently during the first and second years. The DCP supported greater egg weight than the RRP during the second year and permitted better feed conversion during both years. Strain A produced larger eggs than Strain B regardless of treatment (P<.005). When egg production rate and most other response criteria were considered, .5% TP with DCP as the supplemental source gave the best results in both production years. A TP of .6% from RRP-2 gave similar results in both years. (Key words: phosphorus level, source, laying chickens, two strains) 1984 Poultry Science 63:2007-2019 INTRODUCTION The phosphorus requirement of laying hens is still a major concern in the poultry industry. This concern is primarily one of economics, since the cost of feed grade phosphate has greatly increased following the 1973 to 1974 energy crisis that led to a shortage of feed phosphate supplements. Nutritionists reacted to the problem of a feed phosphate shortage by attempting to
1 Published as Paper Number 7113, Journal Series, Nebraska Agricultural Experiment Station. 2 From a dissertation submitted by the senior author in partial fulfillment of requirements for the Ph.D. degree. 3 To whom correspondence should be addressed.
define more accurately minimum phosphorus requirements and by evaluating alternate and less expensive sources of phosphorus. However, when considering the phosphorus requirements of layers, one cannot ignore differences in availability among phosphorus sources and possible differences among various genetic strains as to minimum phosphorus requirement. Possible differences in the phosphorus requirement of hens or differences in the ability of birds to utilize phosphorus from different sources have been reported (Charles et al., 1978; Tennessee Random Sample Studies, 1973; Francis, 1957; Ingram et al., 1976). Few experiments have been conducted during the last 10 years as to the use of raw rock phosphate (RRP) as a supplement for
2007
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(Received for publication March 14, 1983)
2008
SAID ET AL.
MATERIALS AND METHODS
Nine hundred sixty White Leghorn-type hens 26 weeks of age were housed at the rate of 3 birds per cage measuring 45.7 x 30.5 cm. There were 480 birds from each of two commercial strains, DeKalb and Hisex, which were designated A and B, respectively. The experiment was conducted at the Arlington Poultry Research Farm, University of Wisconsin, Madison. The study was initiated October 14, 1977. Thirty hens of either strain were assigned randomly to 10 consecutive cages sharing a common feeder; this housing arrangement allowed 32 experimental units in total. Water was supplied ad libitum by a Hart cup in each cage of 3 birds. Eight dietary treatments were then randomly assigned to the 32 experimental units. A
treatment group consisted of four experimental units that included two replicates of each strain (a total of 120 birds). The experimental diets are presented in Table 1. The basal ration (Diet 1) was formulated to contain .4% TP. Diets 2, 3, and 4 were formulated to contain .5, .6 and .7% TP, respectively, using DCP to replace appropriate quantities of corn and limestone in the basal ration. Diets 5 and 6 were formulated to contain .5 and .6% TP, respectively, using raw rock phosphate (RRP-1). Diets 7 and 8 were formulated to contain .5 and .6% TP, respectively, using a second sample of raw rock phosphate (RRP-2). The two RRP used in Diets 5 through 8 replaced appropriate amounts of corn and ground limestone in the basal ration. Ingredient levels, calculated composition, and laboratory analysis of the eight diets are presented in Table 1. Fluorine content was found to be 3.60 and 3.67% in RRP-1 and RRP-2, respectively. All birds were weighed, beak-trimmed, treated with nicotine sulfate solution (applied to feathers around the vent), and vaccinated for fowl cholera prior to assignment to cages. The appropriate experimental diets were supplied ad libtum. Birds received 14 hr of light daily during both production years. Egg production was recorded daily for each replicate. The percent hen-day average egg production, mortality, and feed consumption were calculated for each replicate of 30 birds every 28 days. Feed efficiency was calculated and expressed in kilograms of feed consumed per dozen eggs produced. Eggs from 3 consecutive days of production within each month were collected from each replicate to obtain egg weight data. Shell quality was measured every 8 weeks beginning at 44 weeks of age and onward using the Marius apparatus under a stress of 500 g on the vertical axis. The same eggs were also used to determine interior quality by measuring the Haugh unit index. At 68 weeks of age, all hens were weighed and force-molted (details of the force-molting procedures have been described by Said et al., unpublished data). After the molt, hens were maintained in the same cages and continued on the same experimental diets for an additional experimental period of 40 weeks. Therefore, treatment effects during the first year could have been continued into the second year or 40 weeks. Data concerning feed consumption, feed efficiency, mortality, average percent hen-day egg production, interior quality, and shell
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chickens, possibly due to poor results in earlier studies. Many factors were apparently involved in the disappointing results with feeding highfluorine rock phosphates in the early studies. Animal feed formulas are now more complete and provide a better nutrient balance than in the 1940's. One specific difference in layer feeds has been the use of lower levels of supplemental phosphorus. For this reason it could be possible that high fluorine phosphate supplements might be safer to use now than in the past. This idea was tested by using different levels of RRP in starting, growing, and laying diets (Said et al, 1979). Results of this study clearly demonstrated that RRP (3.6% fluorine) at .6 and 1.2% could be used in such diets without any deterimental effects on performance of layers during the first and second years of production. Charles et al. (1978) reported that .7% total phosphorus (TP) including supplements of either dicalcium phosphate (DCP) or RRP appeared to provide adequate phosphorus for hens during five 28-day periods. They reported no significant differences in percent egg production, feed consumption rate, feed efficiency, or eggshell quality between hens fed the two different phosphorus sources. The experiment reported herein was conducted primarily to study the response of caged, White Leghorn-type hens to different levels and sources of phosphorus during the first and second years of production under commercial conditions. Two commercial strains of hens were involved in the study.
.404
.507
2.74
2.76 .602
2.75
14.98 2871
100.00
100.00
100.00
100.00
100.00
15.00 2880
.50 .50
.50 .50
.50 .50
.50 .50
270
.504
2.74
2.74 .70
15.03 2888
14.97 2864
.75
.50 .50
69.95 16.60 3.30 2.00 6.40
.95
5
.50
Diets
69.25 16.60 3.30 2.00 6.45 1.40
4
69.45 16.60 3.30 2.00 6.70
3
69.70 16.60 3.30 2.00 6.90
69.90 16.60 3.30 2.00 7.20
2
15.02 2886
1
2
6
1 Supplied the following per kilogram of diet: gallomycin, .022 g; vitamin A, 4000 IU; vitamin D 3 , 1000 ICU: riboflavi nine, .5 g. 2 Additional calcium was provided in the form of oyster shell to all birds (ad libitum) to make the total calcium about
Lab analysis: Total phosphorus, % Fluorine, ppm
Calculated composition: Crude protein, % Metabolizable energy, kcal/kg Calcium, %2
Ground yellow corn Soybean meal (44%) Dehydrated alfalfa (17%) Meat meal (50%) Limestone Dicalcium phosphate Raw rock phosphate-1 Raw rock phosphate-2 Iodized salt Vitamin-mineral premix 1 Total
Ingredients
TABLE 1. Composition of experimental diets and laboratory analyses
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SAID ET AL.
2010
RESULTS AND DISCUSSION Hen-Day Egg Production. The effects of strain, phosphorus source, and level on average percent hen-day production are presented in Tables 3 and 4. Figure 1 shows the strain X diet interaction relative to average hen-day egg production of hens during the second year. This
interaction was apparently due to both levels of dietary phosphorus and source. When DCP was the source of supplemental phosphorus, maximum production by either strain was reached when the diet contained .5% TP. In contrast, when either RRP-1 or RRP-2 was the source of supplemental phosphorus, maximum egg production by either strain occurred only when the diet contained .6% TP, indicating that phosphorus was less available to the hens from RRP as compared to DCP. Although no significant strain effect on average egg production was evident during the first year of production, differences occurred between the two strains during the second year (Tables 3 and 4). Those Strain A hens that received .5% TP from RRP-1 had higher henday egg production than hens receiving .5%TP from RRP-2. However, birds receiving .6% TP from RRP-1 had a much lower rate of egg production as compared with hens fed .6% TP from RRP-2 (Figure 1). At the same time, increasing dietary phosphorus from .5 to .6% TP from RRP-1 resulted in a slight increase in egg production of Strain A. In contrast, the inclusion of .1% more phosphorus from RRP-2 resulted in a dramatic increase in egg production rate. Orthogonal contrast comparisons showed that during the first year feeding the unsup-
TABLE 2. General linear models procedure, split-plot design (whole plot CRD)
Sources of variation
Formula
Degrees of freedom
Factor A "strain" (whole plot) error a replicate within strain Factor B "Trt" 2 Strain X Trt interaction error b Total
a-1 a(w-l)1 b-1 (a-D(b-l) by subtraction awb—1
1 2 7 7 14 31
Orthogonal contrasts Basal diet vs. others Dicalcium phosphate level linear Dicalcium phosphate level quadratic R R P - 1 3 level linear R R P - 2 level linear R R P - 1 vs. R R P - 2 Dical vs. RRP Total 1
Where w = number of experimental units per level of factor A.
2
Trt = Treatment.
3
RRP-1 First sample of raw rock phosphate; RRP-2 = second sample of raw rock phosphate.
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quality were determined as described previously. Before the experiment was terminated, hens were weighed and three birds from each replicate (12 hens/treatment) were selected at random and sacrificed by cervical dislocation. Right tibiae were excised and cleaned of adhering tissues. Percent ash was determined for the dry, fat-free' bones. Samples of tibia ash were then assayed for fluoride content using the Technicon autoanalyzer (Technicon Instrumentation Corporation, Ardsley, NY). Productive performance and egg quality data from each year were analyzed by the Statistical Analysis System (SAS) by Barr et al. (1979). The general linear models procedure for split plots (where strain was considered as complete randomized whole plot and the treatment as the split plot) are presented in Table 2. Orthogonal polynomial and least squares mean comparisons were performed.
1
2 3 4
5 6
7 8
Basal
DCP 3 DCP DCP
RRP-1 RRP-1
RRP-2 RRP-2
RRP
NS NS NS NS NS NS NS
71.8 a b 71.7 a b 70.2b 74.0 a
.5 .6
.5 .6
74.0 a 75.2 a 71.7 a b
69.6t>
.5 .6 .7
.4
% TP
NS NS NS NS NS
*** *
107* m a b 118 c 116 c 112abc 116 c 114 b 116bc
115 113 NS
73.0 71.6 NS 2
3.36 3.48 3.42 3.48
.570 .696
3.33 3.54 3.57
3.21
3.45 3.39
.560 .696
.555 .708 .812
.428
.632 .622
Daily consumption (g/her /day; TP 1 Ca
*+*
NS
** * • **
NS
***
NS
1.95c 1.88 b
1.89b 1.97c
1.81 a 1.90 b 1.97c
1.91 b
1.92 1.91 NS
(kg/doz)
DCP = Dicalcium phosphate, RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
NS = Nonsignificant.
TP = Total phosphorus.
***P<.005.
*'P<.01.
2.6 2.5
2.6 2.6
2.4 2.6 2.7
2.6
2.7 2.6
(kg
Feed/eggs
' ' ' ' Means followed by different superscripts within the same column are significantly different (P<.05).
*P<.05.
3
2
1
ji h r fl p
DCPDS.
Effect Basal vs. others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2
Diet
p Supplement
Strain A Strain B
(g/hen/ day)
Feed consumption
(%)
Hen-day egg production
TABLE 3. Effect of strain and phosphorus (P) source and level on performance of he
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7 8
RRP-2 RRP-2
,e
100 b
96a
10lb 100 b
48.7 c d 51.0 C
47.9 d 55.2°
* *** * ***
NS
** ***
NS
*** ** * ***
100b 104 c 103 c
57.6 a 56.4 a b 53.2t>c
** ***
96*
50.0 C
99 101 NS 2
51.1 53.9
.505 .600
.480 .600
.500 .624 .721
.384
.544 .555
TP1
3.03 3.00
2.88 3.00
3.00 3.12 3.09
2.88
2.97 3.03
Ca
Daily consumption (g/hen/day)
(kg/doz)
** *
NS
** ***
NS
***
NS
2.60 e 2.22 b
2.45 e 2.37 d
2.09 2.2lb 2.32 c d
a
2.29 c
2.34 2.30
DCP = Dicalcium phosphate, RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
NS = Nonsignificant.
***P<.005.
**P<.01.
hen
3.3 2.8
3.2 3.0
2.7 2.8 3.0
3.0
2.9 3.0
(kg
Feed/eggs
Means followed by different superscripts within the same column are significantly different (P<.05).
.5 .6
.5 .6
.5 .6 .7
.4
%TP
TP = Total phosphorus.
' ' '
c
*P<.05.
3
2
1
a
Effect Basal vs . others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2 DCP vs. R R P
5 6
RRP-1 RRP-1
DCP DCP
DCP
2 3 4
1
Basal
3
Diet
Supplement
Strain A Strain B
(g/hen/ day)
Feed consump-
<%)
Hen-day egg production
TABLE 4. Effect of strain and phosphorus (P) source and level on performance'of
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PHOSPHORUS AND EGG QUALITY
P-.
.6
Strain A Strain B -I .7
DIETARY TOTAL PHOSPHORUS, %
FIG. 1. Strain X diet interaction (P<.05) as to average hen-day egg production, second year. DCP= Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
plemented diet (#1) did not result in a significant decrease (.05
phorus did not result in a significant increase in egg production rate during either year (Tables 3 and 4). On the contrary, Diet 4, which contained .7% TP, was associated with a lower rate of egg production as compared with Diets 2 or 3, which contained .5 and .6% TP., respectively. A comparison of the two RRP as to the effect on egg production revealed that RRP-2 was significantly better (P<.05) than RRP-1 as a phosphorus source for force-molted hens. Such differences did not exist during the first year of production. The performance of hens fed the RRP diets indicate that RRP could be used successfully as a source of phosphorus for layers. These results agree with previous findings in our laboratory (Said et al., 1979) even though hens in the present study were housed in cages, whereas in the earlier study hens were maintained in floor pens. Feed Consumption. Data in Tables 3 and 4 show no significant differences between Strain A and B in feed consumption throughout the entire experiment. Hens receiving the unsupplemented diet (#1) consumed significantly less feed (P<.005) as compared to the average feed consumption of hens receiving diets supplemented with inorganic phosphorus. These results do not agree with the findings of Ademosun and Kalango (1973), who reported phosphorus levels did not affect feed intake of laying hens. However, Summers et al. (1976) reported that feed intake was depressed only when the available phosphorus (AP) was reduced to .15% (inorganic phosphorus). Our results support the finding of Summers et al. (1976) and Hurwitz and Bornstein (1963). However, our data disagree with the results of Hamilton and Sibbald (1977) who reported variation in dietary phosphorus levels had no significant effect on either feed consumption or feed efficiency. It should be noted, however, that the lowest phosphorus level used by Hamilton and Sibbald (1977) was .45% AP (.60% TP), which is certainly well above the minimum requirement. Birds fed diets supplemented with DCP consumed comparable amounts of feed as hens fed the RRP diets (Table 3) during the first year of production. However, a highly significant difference (P<.005) existed during the second year; birds that received the RRP diets consumed less feed than those fed the DCP diets. The higher egg production rate of hens receiving DCP and the possible accumulative
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_
2013
2014
SAID ET AL.
rates of production. Egg Shell Quality as Measured by Deformation. Data presented in Tables 3 and 4 show the effect of strain, level, and source of phosphorus on egg shell quality. No significant differences (.05
63 -1
58-
d
/
BASAL
.
strain A Strain B
57-
'.' tlh .4
r— .5
~i .6
1 .7
DIETARY TOTAL PHOSPHORUS, %
FIG. 2. Strain X diet interaction (P<.005) as to average egg weight, first year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
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effect of fluorine from RRP diets might explain these differences. Feed Conversion. When DCP was the source of supplemental phosphorus, both strains showed maximum efficiency of feed conversion with .5% TP. Increasing the phosphorus to .6 and .7% TP resulted in a linear increase in the amount of feed required to produce a dozen eggs (Tables 3 and 4). An opposite trend was found when RRP-2 was the source of phosphorus. This trend in feed conversion can be explained simply by the fact that hens fed .6% TP from RRP-2 (Diet 8 produced significantly more (P<.05) eggs as compared to hens receiving .5% TP from RRP-2 (Diet 7), although both groups consumed nearly comparable amounts of feed (Tables 3 and 4). No significant differences (,05
PHOSPHORUS AND EGG QUALITY
A... ^ - ^ . O
/
RRP-1
«s-
• - - O DCP
-—Strain B
BASAL
DIETARY TOTAL PHOSPHORUS,
FIG. 3. Strain X diet interaction (P<.005) as to average egg weight, second year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
units in eggs collected either from Strain A or B (Fig. 4). While in contrast, increasing the total phosphorus level from RRP-1 seemed to steadily lower the interior quality of eggs collected from either strain. There seems to be no apparent explanation for the dramatic differences in the interior quality of eggs collected from hens fed the two different RRP. One can only speculate that RRP-1 may have possibly contained certain trace elements such
as vanadium, which could have decreased albumin quality (Berg et al., 1963) and consequently decreased Haugh units. When the interior quality of eggs collected from hens receiving the basal diet was compared to the average Haugh units of eggs collected from all other treatments, no significant differences were found. Phosphorus from DCP, RRP-1, and RRP-2 showed significant linear effects as to Haugh unit values of eggs collected during the first and second year of production (Tables 3 and 4). A highly significant difference was found between RRP-1 and RRP-2 as to the effect on Haugh unit values during the 2 years of production. Although those hens fed the RRP diets produced eggs with significantly higher interior quality (P<.005) during the first year as compared with those fed the DCP, these differences seemed to diminish as the hens progressed in age (Table 4). Hamilton and Sibbald (1977) reported a highly significant effect of strain (P<.005) on Haugh unit values at different periods of their experiment. A less profound effect of strain on Haugh unit values was found in the present study (Tables 3 and 4) and favored Strain A over Strain B. Survival Rate. Percent survival data of hens given the various dietary treatments are presented in Table 5. All groups exhibited very high survival rates throughout the first and second years of production. The overall mortality during the force molt period (35 days) was 4.2%. This mortality was apparently not influenced by dietary phosphorus treatments
BASAL
"•--• —
•S'-
.4
T
~\— .6
Strain B
-I .7
DIETARY TOTAL PHOSPHORUS, I
FIG. 4. Strain X diet interaction (P<.01) as to interior quality of eggs (Haugh units), first year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
•4
.5
.6
DIETARY TOTAL PHOSPHORUS, %
FIG. 5. Strain X diet interaction (P<.005) as to interior quality of eggs (Haugh units), second year. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1 and second (RRP-2) sample.
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.Strain A —
a
2015
99.4 98.3 98.2 99.1
+ 173 + 229 + 211 + 144
1 7 5 9 + 173 1795 + 176 1 7 5 4 ± 169 1740 ± 180
1586 ± 1 8 0 1566 ± 179
1543 ± 185 1596 ± 183
5 6
7 8
RRP-1 RRP-1
RRP-2 RRP-2
2
1
99.0 98.4 98.4
+ 184 + 240 + 222
1783 ± 155 1 8 3 9 ± 181 1823 ± 191
1599 + 2 0 1 1599 ± 194 1601 + 191
.5 .6 .7
TP = Total phosphorus; DCP = dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2)
Values are means ± standard deviations from the means.
.5 .6
.5 .6
99.3
+ 106
1 6 7 0 ± 143
1564 ± 192
.4
1
2 3 4
98.9 98.6
(%)
DCP DCP DCP
+ 245 + 132
(g) 1 8 9 8 ± 175 1643 ± 173
1653 ± 192 1511 ± 144
Survival after 1 yr
Basal
TP2
Diet
Supplemental
Strain A: Strain B:
Body weight change
Body weight after 1 y r
Initial body weight
TABLE 5. Average body weights, body weight changes, and survival during the first and seco
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PHOSPHORUS AND EGG QUALITY
Table 5. Dietary phosphorus level apparently affected body weight gain, because those hens receiving the basal diet (.4% TP) gained the least body weight at the end of first year. Increasing dietary phosphorus from DCP resulted in a steady increase in body weight with the maximum at .6% TP for both years. The same trend was evident when RRP-1 was the source of phosphorus. The reverse was true when RRP-2 was the source, as birds receiving .5% TP from RRP-2 gained a little more weight as compared to those receiving .6% TP from the same source. The different responses to dietary RRP may be related to the fluorine content or availability of these samples. The RRP-2 contained a slightly higher level of fluorine than RRP-1 (Table 1). Also, the two RRP could have
TABLE 6. Influence of strain and phosphorus source and level on percent bone ash and fluoride content of ash, (end of second year)
Bone ash
Strain A: Strain B; Supplemental P Basal DCP DCP DCP
Diet
TP
Fluoride in ash
(%)
(ppm)
58.76 58.17 NS
4648 4022
***
2
55.42 c ab
1702 d 1477 d 1552 d 1466 d
RRP-1 RRP-1
59.23 61.87 a 61.12 a 57 7 2 b c 58.13 b
5472 c 9219 a
RRP-2 RRP-2
57.15 b c 57.07 b c
6802 b 6990°
Probabilities of significance1
Effect Basal vs. others P Level linear, DCP P Level quadratic, DCP P Level linear, RRP-1 P Level linear, RRP-2 RRP-1 vs. RRP-2 DCP vs. RRP
** * NS NS NS NS NS
NS NS
***
NS
***
' ' ' ' Means followed by different superscripts within the same column are significantly different (P<.05). 1
NS = Nonsignificant.
2
TP = Total phosphorus; DCP = dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second ' (RRP-2) sample. *P<.05. ***P<.005.
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of the first year. No significant differences ( 0 5 < P < . 1 0 ) in survival were found among different dietary phosphorus levels or sources. Survival data presented in Table 5 for the second year reflect only mortality that occurred in the 280-day postmolt experimental period. Strain had no significant effect on the survival rate of hens. These findings were in agreement with those of Hamilton and Sibbald (1977). Body Weight Gain. The maximum average difference in the initial body weight among the various treatment groups (58 g) was quite small. The average initial body weight of Strain A was 152 g greater than for Strain B. The average body weights and changes in body weight at the end of the first and second years are shown in
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SAID ET AL.
feed/hen per day during the first year of production, which is in total agreement with the National Research Council (1977) recommendation. However, when the RRP furnished the supplemental phosphorus, the level of phosphorus needed for optimum performance during the first year was .6% TP. During the second year, the optimum performance of hens was again reached when their diet contained .5% TP from DCP or .6% TP from the two RRP. However, the birds consumed less feed during the second year as compared to the first year. On the basis of actual phosphorus requirement in terms of mg/hen per day, our data indicate that the laying hen required about 550 mg of total phosphorus per day during the first year of production for optimum performance, whereas the requirement was about 500 mg TP per hen per day during the second year of production for optimum performance. Mean daily consumptions of TP and calcium in g/hen per day for hens receiving each treatment are presented in Tables 3 and 4. The data also clearly indicate that RRP were of lower biological availability as compared to DCP but could be used successfully in layer rations if slightly higher levels are fed. This was especially true for RRP-2. Consideration should be given to fluorine when higher levels of RRP are used. Strain of bird influenced egg weight during the first year of production (Table 3) and also egg weight, egg production rate, feed con-
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.5
.6
DIETARY T O T A L PHOSPHORUS. %
FIG. 6. Dosage response curve for dicalcium phosphate illustrating the method of calculating biological availability of phosphorus from the RRP relative to DCP. DCP = Dicalcium phosphate; RRP = raw rock phosphate, first (RRP-1) and second (RRP-2) sample.
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differed as to contents of other toxic trace elements. Bone Ash Percent. The influence of phosphorus level, source, and strain on the percent bone ash is shown by data presented in Table 6. When compared with the average values of hens fed the supplemented diets, birds that received the basal diet had a s i g n i f i c a n t l y lower (P<.005) percent bone ash, indicating the marginal TP level in this diet (#1). Increasing phosphorus in the diet resulted in a numerical increase in bone ash percent, but the increase was not significant (.05
PHOSPHORUS AND EGG QUALITY
REFERENCES Ademosun, A. A., and I. O. Kalango, 1973. Effect of calcium and phosphorus levels on the performance of layers in Nigeria. 1. Egg production eggshell quality, feed intake and body weight. Poultry Sci. 52:1383-1392. Anderson, J. O., J. S. Hurst, D. C. Strong, H. Nielsen, D. A. Greenwood, W. Robinson, J. L. Shupe, W. Binns, R. A. Bagley, and C. I. Draper, 1955. Effect of feeding various levels of sodium fluoride for growing turkeys. Poultry Sci. 34:1147— 1152. Arscott, G. H., P. Rachapaetaryakom, P. E. Bernier, and F. W. Adams, 1962. Influence of ascorbic acid, calcium, and phosphorus on specific gravity of eggs. Poultry Sci. 41:485-488. Barr, A. J., J. H. Goodnight, J. P. Sail, W. H. Blair, and D. M. Chilko, 1979. SAS User's Guide, 1979 ed. J. T. Helwig and K. A. Council, ed. SAS Inst., Inc., Raleigh, NC. Berg, L. R., G. E. Bearse, and L. H. Merrill, 1963. Vanadium toxicity in laying hens. Poultry Sci. 42.1407-1411. Bletner, J. K., and G. C. McGhee, 1975. The effect of phosphorus on egg specific gravity and other production parameters. Poultry Sci. 54:1736. (Abstr.) Charles, O. W., S. Duke, and B. Reddy, 1978. Effect of phosphorus source and level on laying hen performance under varying temperature conditions. Pages 74 to 87 in Proc. 1978 Georgia Nutr.
Conf. Edwards, H. M., Jr., and F. A. Suso, 1981. Phosphorus requirement of six strains of caged laying hens. Poultry Sci. 60:2346-2348. Francis, D. W., 1957. Strain differences in the incidence of cage layer fatigue. Poultry Sci. 36: 181-183. Guenter, W., 1980. Dietary phosphorus and laying hen performance. Poultry Sci. 59:1615. (Abstr.) Haman, K., P. H. Phillips, and J. G. Halpin, 1936.The distribution and storage of fluoride in the tissues of the laying hen. Poultry Sci. 15:154-157. Hamilton, R.M.G., and I. R. Sibbald, 1977. The effects of dietary phosphorus on productive performance and egg quality of ten strains of WhiteJLeghorns. Poultry Sci^56:1221-1228. Holder, D. P., 1981. Dietary phosphorus requirements of force-molted Leghorn hens. Poultry Sci. 60:433-437. Hurwitz, S., and S. Bornstein, 1963. The effect of calcium and phosphorus in the diet of laying hens on egg production and shell quality. Isr. J. Agric. Res. 13:147-154. Ingram, R. F., J. K. Bletner, and G. McGhee, 1976. The response of four strains of Single Comb White Leghorn layers to two levels of dietary phosphorus. Poultry Sci. 55:2077. (Abstr.) Mostert, G. C , and L. G. Swart, 1968. Ca and P in laying rations for hens. S. Afr. J. Agric. Sci. 11:687-695. National Research Council, 1977. Nutrient Requirements of Poultry. 7th rev. ed. Natl. Acad. Sci., Washington, DC. Said, N. W., M. L. Sunde, H. R. Bird, and J. W. Suttie, 1979. Raw rock phosphates as a phosphorus supplement for growing pullets and layers. Poultry Sci. 58:1557-1565. Salman, A. J., and J. McGinnis, 1968. Availability of phosphorus from plant origin for layers. Poultry Sci. 47:1712-1713. Saville, P. D., 1967. Water fluoridation: Effect on bone fragility and skeletal calcium content in the rat. J. Nutr. 91:353-357. Summers, J. D., R. Grandhi, and S. Leeson, 1976. Calcium and phosphorus requirements of laying hens. Poultry Sci. 55:402-412. Tennessee Random Sample Laying Test (16th), 1973. Univ. Tennessee, Knoxville, TN.
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version, and interior quality of the eggs during the second year of production (Table 4). Among the factors that should be considered in determining the hen's phosphorus requirement are: strain of bird, bioavailability and composition of the phosphorus source, and conditions of the experiment. These factors should be indicated and emphasized to clarify some of the controversy relating to the dietary phosphorus requirement of layers. Strain of bird, bioavailability of P sources, and experimental conditions were clearly specified in the present study.
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