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The Potential Use of Dietary Salt Deficiency for the Force Resting of Laying Hens1
The Potential Use of Dietary Salt Deficiency for the Force Resting of Laying Hens l W.
G.
NESBETH, C. R. DOUGLAS AND R.
H.
HARMS
Department of Poultry Science, Florida Agricultural Experiment Station, Gainesville, Florida 32611 (Received for publication March 19, 1976)
POULTRY SCIENCE 55: 2375-2379,
INTRODUCTION
C
ONDITIONS of the egg industry sometimes cause the producer to use his hens for more than one year of production. Various techniques have been used to cause old laying hens to cease production and allow them a period of rest and rejuvenation. Wilson et al. (1969) evaluated several molting methods and recommended the removal of feed for seven days and water for the first three days. They suggested that the hens be placed on a 9.7% protein diet for 28 days and then returned to control diet. Adams (1955, 1956), Himeno and Tanabe (1957) and Shaffner (1955) effected force molting by administering progesterone to laying hens. Arrington et al. (1967) and Perdomo et al. (1966) found that high dietary iodine caused a cessation of production. Hansen (1960) compared several molting methods including feed and water restriction, progesterone administration with
1. Florida Agr. Exp. Sta. Journal Series No. 9002.
2375
1976
and without feed restriction and the addition of 0.15% of 2-acetyl-amino-t-nitrothiazol (enheptin-A) to the diet. All of the above results indicated increased shell thickness and improved albumen quality. Other investigators (Berg and Bearse, 1947; Snyder and Orr, 1960) also reported improvement in egg shell and interior quality following the molt. Nevertheless, Len et al. (1964) showed that the improvement in shell thickness and Haugh unit scores of eggs laid in the post-molt period were only temporary. Bell (1967) and Bundle (1974) also determined the economics of various molting methods and reported that most of these systems gave comparable results regardless of the method used for molting. The restriction of calcium intake has been shown to be effective in causing a resting phase in laying hens (Douglas et al., 1972; Blair and Gilbert, 1973; and Martin et al, 1973). That low dietary salt can also effect a pause in egg production was demonstrated by Whitehead and Shannon (1974) and Nesbeth et al. (1976).
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ABSTRACT Two experiments using a total of 240 laying hens housed in individual cages were conducted to evaluate dietary salt deficiency as a potential tool for the force resting of laying hens. The control group of hens received the corn-soy diet with 0.25% added salt. Another group of hens received a basal corn-soy diet with no added salt for six weeks then was returned to the control diet. The third group was subjected to the force molting technique recommended by Wilson et al. (1969). The drinking water, given ad libitum, and the basal diet contained 26 p.p.m. and 270 p.p.m. sodium, respectively. Hen weight, feed consumption, egg production, egg weight and egg specific gravity were recorded throughout each experiment. Feed consumption and body weight of hens receiving the low salt diet (Treatment 2) or forced molted (Treatment 3) decreased significantly and egg production ceased during the molt period. The reproductive organs of hens fed the low salt diet regressed to about 25% of the original size. When hens were returned to control feed, recovery was complete with significant increases in egg weight and egg specific gravity for hens on treatment two. Egg production was significantly higher for both the hens which received low salt and those force molted, compared to the control birds during the post molt period. The results of the experiments indicated that dietary salt deficiency is effective for the force resting of laying hens.
2376
W. G. NESBETH, C. R. DOUGLAS AND R. H. HARMS
TABLE 1.—Composition of diets Control
Yellow corn meal Soybean meal (50% protein) Alfalfa meal (20% protein) Ground limestone (38% Ca.) Dicalcium phosphate (18.5% P, 24% Ca.) Iodized salt Micro-ingredient mix'
69.28
69.53
19.00
19.00
2.50
2.50
6.22
6.22
2.25 0.25 0.50
2.25
Low salt
(%)
— 0.50
'Supplied per kg. of diet: 6,600 I.U. Vit. A; 2,200 I.C.U. vit. D 3 ; 2.2 mg. menadione dimethylpyrimidinol bisulfite (MPB); 4.4 mg. riboflavin; 13.2 mg. pantothenic acid; 39.6 mg. niacin; 499.4 mg. choline chloride; 22 meg. vit. B 12 ; 125 mg. ethoxyquin; 60 mg. manganese; 50 mg. iron; 6 mg. copper; 198 meg. cobalt; 1.1 mg. iodine; 35 mg. zinc. The studies reported herein were conducted to evaluate the potential of dietary salt deficiency for the force resting of laying hens. EXPERIMENTAL PROCEDURE Experiment 1. A total of 120, 68-week-old laying hens (Babcock B-300) in individual cages were randomly divided into three experimental groups. The experiment was conducted during the months of February to
The hens were weighed individually at the start of the experiment, at 42 days and at the end of the experiment. Feed intake was measured daily for the first 28 days of the experiment as well as the first seven days following the return of groups two and three to the control diet and then every 28 days. Weight and specific gravity of eggs were determined on all eggs laid on two days per week. At weekly intervals one to three hens on the low salt diet were sacrificed for observation of the reproductive organs. The drinking water, and the experimental diets were given ad libitum. The sodium content of water and basal diet were determined by atomic absorption spectrophotometry and contained 26 p.p.m. and 270 p.p.m., respectively.
TABLE 2.—Feed intake and body weights of hens on three treatments1 Body weights (g.) Feed intake ( g./hen/day)
Weeks of experiment
M2
PM 3
6
9
30
Control Low salt Molt
102.3 63.5 70.0
(Experiment 1) 97.8 1564.7a 97.1 1287.0c 98.1 1414.5b
1580.0a 1326.9b 1352.0b
1597.6a 1596.6a 1567.0a
1531.2a 1521.7a 1516.6a
Control Low salt Molt
98.9 56.5 62.9
(Experiment 2) 93.6 1604.2a 95.6 1207.7b 94.5 1176.4b
1652.2a 1190.3c 1312.9b
1535.2a 1485.1a 1504.2a
1502.7ab 1466.5b 1540.7a
Treatn tient
3
'Means without common letters in the same column are significantly different (P < .05). = Molt (6 weeks). PM = Post Molt (24 weeks). 2 M 3
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Ingredients
September. One group of hens served as control, and was fed a corn-soy laying diet (Table 1) containing 0.25% added salt. A second group of hens received the basal corn-soy diet containing 270 p.p.m. sodium with no added salt for a period of 42 days (molt period). The hens in treatment group three were subjected to the molting procedure recommended by Wilson et al. (1969). This treatment was started seven days after hens in group two were placed on the low salt diet so that all hens could be returned to control diet simultaneously. At 42 days all hens were placed on the control diet.
2377
SALT DEFICIENCY AND FORCE RESTING
Experiment 2, The procedure used in this experiment was similar to that used in Experiment 1. It was conducted during the period of October to May, and no hens were sacrificed. RESULTS AND DISCUSSION
TABLE 3.—Ovary and oviduct weights of hens fed a diet containing no added salt % of body weight Weeks of experiment Organ Ovary Oviduct 1
PE 1
2
3
4
6
3.61 3.26
0.43 2.00
0.47 1.15
0.27 1.00
0.43 1.13
PE = Pre-Experiment. TABLE 4.-—Egg
production, egg weight and egg specific gravity of hens on three treatments'
Egg production (%i hen-day) M2
PM 3
Control Low salt Molt Control Low salt Molt
Treatment
Egg speciifie gravity
PM
M
PM
64.9 12.8 12.6
(Experiment 1) 63.8a 63.4a 72.1b 63.4a 71.4b 63.8a
60.0a 62.7b 60.7a
1.080a 1.080a 1.077a
1.073a 1.078b 1.073a
62.1 11.9 12.1
(Experiment 2) 51.4a 61.4a 61.2b 61.6a 57.5b 62.8b
61.3a 65.4b 62.7a
1.075a 1.076a 1.076a
1.076a 1.086c 1.081b
1 Means without common letters 2 M = Molt (6 weeks). 3 PM = Post Molt (24 weeks). 4
PE = Pre-Experiment.
Egg weight (g.) PE 4
in the same column are significantly different (P < .05).
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A marked reduction in feed intake occurred within the first 24 hours with hens fed the low salt diet. After 10 days, feed intake had decreased to 40% of the controls. The hens receiving the low salt diet during the six-week molt period consumed 63.5 and 56.5 grams per hen per day in Experiment 1 and 2, respectively (Table 2). This was a considerable reduction when compared to the controls and was slightly lower consumption than the hens molted on the procedure as outlined by Wilson et al. (1969). When the hens were returned to the diet containing salt, feed intake increased immediately, and during the post-molt period no significant differences between treatments could be detected.
After the hens had been receiving the low salt diet for three weeks, they had lost approximately 20% of their body weight (Table 2). Within three weeks (9th week of experiment) after returning the hens to the diet containing salt, they had regained body weight equal to controls. At the end of the experiment, there were no significant differences among body weights of hens on either of the three treatments. There was a slight reduction in body weight of all hens during the experimental period which possibly was due to the high environmental temperature. Hens fed the low dietary salt had a reduction in ovary and oviduct weights (Table 3). However, after the hens had been receiving the low dietary salt for 42 days, some hens still had ovaries and oviducts similar in weight to those of control hens. These ovaries had large follicles which were apparently mature and near the stage of ovulation. Egg production was reduced to less than 3% after the hens had been receiving the
2378
W. G. NESBETH, C. R. DOUGLAS AND R. H. HARMS
There was no significant difference in specific gravity of eggs among the three treatments during the molt period (Table 4). However, specific gravity of eggs from hens force rested by feeding the low dietary salt was significantly higher in both experiments than eggs from either the control group or hens force molted by the conventional method. Force molting the hens with a conventional method resulted in significantly improving egg specific gravity in Experiment 2, however, there was no beneficial affects in Experiment 1. In both experiments, some of the hens fed the low salt diet started to molt by the 13th day; however, most of the birds ceased production and did not molt. All hens appeared normal throughout the experiment and there was no excessive mortality on any of the treatments. The data in this paper indicate that hens can be fed a diet containing low salt which will result in a cessation of egg production.
This finding agrees with previous reports by Whitehead and Shannon (1974) and Nesbeth et al. (1976). It would appear that this method of force resting would be preferred over previously recommended methods of force resting. The use of low dietary salt could initiate a pause in egg production and would be preferred over feeding a low dietary calcium, since feeding the low dietary salt does not result in a depletion of calcium from the skeleton. The feeding of the low dietary salt resulted in egg production equal to that of hens molted by the method suggested by Wilson et al. (1969) and egg shell quality was better with hens rested on this program. Hens fed the low dietary salt did not appear to be under any stress; therefore, this method could be adapted for use in commercial egg production without any apparent problems. When low dietary levels of salt are used for force resting of hens, attention should be given to the dietary sodium level as well as the level of sodium in the drinking water. In this experiment, the diet and drinking water contained 270 and 26 p.p.m. of sodium, respectively. REFERENCES Adams, J. L., 1955. Progesterone-induced unseasonable molt in Single Comb White Leghorn pullets. Poultry Sci. 34: 702-707. Adams, J. L., 1956. A comparison of different methods of progesterone administration to the fowl in affecting egg production and molt. Poultry Sci. 35: 323326. Arrington, L. R., R. Santa-Cruz, R. H. Harms and H. R. Wilson, 1967. Effects of excess dietary iodine upon pullets and hens. J. Nutr. 92: 325-330. Bell, D., 1967. Characteristics of force-molted flocks. Feedstuffs, 39(26):21. Berg, L. R., and G. E. Bearse, 1947. Changes in egg quality from force molting White Leghorn yearling hens. Poultry Sci. 26: 414-418. Blair, R., and A. B. Gilbert, 1973. The influence of supplemental phosphorus in a low-calcium diet designed to induce a resting phase in laying hens. Br. Poultry Sci. 14: 131-135. Bundle, E., 1974. Extent of future molting depends on many factors. Feedstuffs, 46(46): 18, 20.
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low salt diet for three weeks. However, some of the birds continued to lay a few eggs during the molt period. This resulted in egg production being reduced to approximately 12% during the molt period (Table 4). The hens force molted according to the procedure of Wilson et al. (1969) had a rate of lay comparable to that of birds on low salt during the six weeks molt period. The hens on the low salt treatment began to increase in egg production after they had been returned to the diet containing salt for 12 days. Egg production was significantly increased during the post-molt period by both resting procedures. There was no significant difference between the two methods of resting. Eggs were significantly heavier during the post-molt period when hens were force rested by feeding the low dietary salt (Table 4). There was no significant difference in egg weights between the control hens and hens force molted according to the procedure of Wilson et al. (1969).
2379
SALT DEFICIENCY AND FORCE RESTING
1976. Response of laying hens to a low salt diet. Poultry Sci. 55: 000-000. Perdomo, J. T., R. H. Harms and L. R. Arrington, 1966. Effect of dietary iodine upon egg production, fertility and hatchability. Proc. Soc. Exp. Biol. Med. 122: 758-760. Shaffner, C. S., 1955. Progesterone induced molt. Poultry Sci. 34: 840-842. Snyder, E. S., and H. L. Orr, 1960. The effect of length of lay, holding temperature, holding time and forced molting on egg quality. Poultry Sci. 39: 1297. Whitehead, C. C , and D. W. F. Shannon, 1974. The control of egg production using a low sodium diet. Br. Poultry Sci. 15: 429-434. Wilson, H. R., J. S. Moore, A. W. O'Steen, J. L. Fry and R. H. Harms, 1969. Force molting of laying hens. Florida Exp. Sta. Bui. 728.
The Arginine Requirement of the 4-7 Week Old Broilerl J. W.
KESSLER AND O.
P. THOMAS
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication March 22, 1976)
ABSTRACT Two floor pen studies were conducted to determine the minimum arginine level needed to support maximum weight gain and optimum feed conversion during the 4-7 week period of growth for both males and females. Floor feather counts were used as an additional criteria for determining the arginine requirement. The basal diets were calculated to contain 0.74 and 0.80% arginine based on the analyzed values for corn, corn gluten meal, skimmilk and soybean meal. Regression equations were calculated from the data obtained for the males only. Based on the regression equations, the calculated requirement for maximum weight gain, optimum feed conversion, and floor feathers is 1.09, 1.10, and 1.13% arginine, respectively. When expressed as a function of energy, these requirements would be 0.329, 0.332, and 0.341% arginine per megacalorie of metabolizable energy per kg. of diet, respectively. The differences in rate of gain data for the females were non-significant, indicating the requirement of the females to be less than the males. The female requirement, based on floor feathers, would appear to be 0.98% dietary arginine. POULTRY SCIENCE 55: 2379-2382,
INTRODUCTION
R
E S E A R C H data indicating the arginine requirement of the 4 - 7 week old broiler could not b e f o u n d in t h e literature. C o m b s (1970) r e c o m m e n d s an amino acid-metabolizable energy ratio of 0.77 for arginine in broiler rations during the 5-8 week period
1. Scientific Article No. A2198 Contribution No. 5176 of the Maryland Agricultural Experiment Station (Department of Poultry Science).
1976
of growth. This ratio relates to m o d e r a t e environmental t e m p e r a t u r e conditions and should be increased by 5 to 10% for s u m m e r feeding conditions w h e r e hot weather is e x p e c t e d . T h e National A c a d e m y of Sciences (1971) lists the arginine requirement of t h e broiler for the 0-6 w e e k period of growth t o be 1.40% of the diet and 1.20% for the 6-9 week period. T h o m a s et al. (1975) revised t h e tables published by C o m b s (1970). H o w e v e r , the revisions m a d e did not c h a n g e the r e c o m m e n d e d value for arginine during
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 23, 2015
Douglas, C. R., R. H. Harms and H. R. Wilson, 1972. The use of extremely low dietary calcium to alter the production pattern of laying hens. Poultry Sci. 51:2015-2020. Hansen, R. S., 1960. The effect of methods of force molting on reproductive performance of chickens. Poultry Sci. 39: 1257. Himeno, K., and Y. Tanabe, 1957. Mechanism of molting in the hen. Poultry Sci. 36: 835-842. Len, R. E., H. Abplanalp and E. A. Johnson, 1964. Second year production of force molted hens in the California random sample test. Poultry Sci. 43: 638-646. Martin, G. A., T. B. Morris, M. H. Gahle and D. G. Harwood, 1973. Force molting by limiting calcium intake. Poultry Sci. 52: 2058. Nesbeth, W. G., C. R. Douglas and R. H. Harms,
G.
NESBETH, C. R. DOUGLAS AND R.
H.
HARMS
Department of Poultry Science, Florida Agricultural Experiment Station, Gainesville, Florida 32611 (Received for publication March 19, 1976)
POULTRY SCIENCE 55: 2375-2379,
INTRODUCTION
C
ONDITIONS of the egg industry sometimes cause the producer to use his hens for more than one year of production. Various techniques have been used to cause old laying hens to cease production and allow them a period of rest and rejuvenation. Wilson et al. (1969) evaluated several molting methods and recommended the removal of feed for seven days and water for the first three days. They suggested that the hens be placed on a 9.7% protein diet for 28 days and then returned to control diet. Adams (1955, 1956), Himeno and Tanabe (1957) and Shaffner (1955) effected force molting by administering progesterone to laying hens. Arrington et al. (1967) and Perdomo et al. (1966) found that high dietary iodine caused a cessation of production. Hansen (1960) compared several molting methods including feed and water restriction, progesterone administration with
1. Florida Agr. Exp. Sta. Journal Series No. 9002.
2375
1976
and without feed restriction and the addition of 0.15% of 2-acetyl-amino-t-nitrothiazol (enheptin-A) to the diet. All of the above results indicated increased shell thickness and improved albumen quality. Other investigators (Berg and Bearse, 1947; Snyder and Orr, 1960) also reported improvement in egg shell and interior quality following the molt. Nevertheless, Len et al. (1964) showed that the improvement in shell thickness and Haugh unit scores of eggs laid in the post-molt period were only temporary. Bell (1967) and Bundle (1974) also determined the economics of various molting methods and reported that most of these systems gave comparable results regardless of the method used for molting. The restriction of calcium intake has been shown to be effective in causing a resting phase in laying hens (Douglas et al., 1972; Blair and Gilbert, 1973; and Martin et al, 1973). That low dietary salt can also effect a pause in egg production was demonstrated by Whitehead and Shannon (1974) and Nesbeth et al. (1976).
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on April 23, 2015
ABSTRACT Two experiments using a total of 240 laying hens housed in individual cages were conducted to evaluate dietary salt deficiency as a potential tool for the force resting of laying hens. The control group of hens received the corn-soy diet with 0.25% added salt. Another group of hens received a basal corn-soy diet with no added salt for six weeks then was returned to the control diet. The third group was subjected to the force molting technique recommended by Wilson et al. (1969). The drinking water, given ad libitum, and the basal diet contained 26 p.p.m. and 270 p.p.m. sodium, respectively. Hen weight, feed consumption, egg production, egg weight and egg specific gravity were recorded throughout each experiment. Feed consumption and body weight of hens receiving the low salt diet (Treatment 2) or forced molted (Treatment 3) decreased significantly and egg production ceased during the molt period. The reproductive organs of hens fed the low salt diet regressed to about 25% of the original size. When hens were returned to control feed, recovery was complete with significant increases in egg weight and egg specific gravity for hens on treatment two. Egg production was significantly higher for both the hens which received low salt and those force molted, compared to the control birds during the post molt period. The results of the experiments indicated that dietary salt deficiency is effective for the force resting of laying hens.
2376
W. G. NESBETH, C. R. DOUGLAS AND R. H. HARMS
TABLE 1.—Composition of diets Control
Yellow corn meal Soybean meal (50% protein) Alfalfa meal (20% protein) Ground limestone (38% Ca.) Dicalcium phosphate (18.5% P, 24% Ca.) Iodized salt Micro-ingredient mix'
69.28
69.53
19.00
19.00
2.50
2.50
6.22
6.22
2.25 0.25 0.50
2.25
Low salt
(%)
— 0.50
'Supplied per kg. of diet: 6,600 I.U. Vit. A; 2,200 I.C.U. vit. D 3 ; 2.2 mg. menadione dimethylpyrimidinol bisulfite (MPB); 4.4 mg. riboflavin; 13.2 mg. pantothenic acid; 39.6 mg. niacin; 499.4 mg. choline chloride; 22 meg. vit. B 12 ; 125 mg. ethoxyquin; 60 mg. manganese; 50 mg. iron; 6 mg. copper; 198 meg. cobalt; 1.1 mg. iodine; 35 mg. zinc. The studies reported herein were conducted to evaluate the potential of dietary salt deficiency for the force resting of laying hens. EXPERIMENTAL PROCEDURE Experiment 1. A total of 120, 68-week-old laying hens (Babcock B-300) in individual cages were randomly divided into three experimental groups. The experiment was conducted during the months of February to
The hens were weighed individually at the start of the experiment, at 42 days and at the end of the experiment. Feed intake was measured daily for the first 28 days of the experiment as well as the first seven days following the return of groups two and three to the control diet and then every 28 days. Weight and specific gravity of eggs were determined on all eggs laid on two days per week. At weekly intervals one to three hens on the low salt diet were sacrificed for observation of the reproductive organs. The drinking water, and the experimental diets were given ad libitum. The sodium content of water and basal diet were determined by atomic absorption spectrophotometry and contained 26 p.p.m. and 270 p.p.m., respectively.
TABLE 2.—Feed intake and body weights of hens on three treatments1 Body weights (g.) Feed intake ( g./hen/day)
Weeks of experiment
M2
PM 3
6
9
30
Control Low salt Molt
102.3 63.5 70.0
(Experiment 1) 97.8 1564.7a 97.1 1287.0c 98.1 1414.5b
1580.0a 1326.9b 1352.0b
1597.6a 1596.6a 1567.0a
1531.2a 1521.7a 1516.6a
Control Low salt Molt
98.9 56.5 62.9
(Experiment 2) 93.6 1604.2a 95.6 1207.7b 94.5 1176.4b
1652.2a 1190.3c 1312.9b
1535.2a 1485.1a 1504.2a
1502.7ab 1466.5b 1540.7a
Treatn tient
3
'Means without common letters in the same column are significantly different (P < .05). = Molt (6 weeks). PM = Post Molt (24 weeks). 2 M 3
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Ingredients
September. One group of hens served as control, and was fed a corn-soy laying diet (Table 1) containing 0.25% added salt. A second group of hens received the basal corn-soy diet containing 270 p.p.m. sodium with no added salt for a period of 42 days (molt period). The hens in treatment group three were subjected to the molting procedure recommended by Wilson et al. (1969). This treatment was started seven days after hens in group two were placed on the low salt diet so that all hens could be returned to control diet simultaneously. At 42 days all hens were placed on the control diet.
2377
SALT DEFICIENCY AND FORCE RESTING
Experiment 2, The procedure used in this experiment was similar to that used in Experiment 1. It was conducted during the period of October to May, and no hens were sacrificed. RESULTS AND DISCUSSION
TABLE 3.—Ovary and oviduct weights of hens fed a diet containing no added salt % of body weight Weeks of experiment Organ Ovary Oviduct 1
PE 1
2
3
4
6
3.61 3.26
0.43 2.00
0.47 1.15
0.27 1.00
0.43 1.13
PE = Pre-Experiment. TABLE 4.-—Egg
production, egg weight and egg specific gravity of hens on three treatments'
Egg production (%i hen-day) M2
PM 3
Control Low salt Molt Control Low salt Molt
Treatment
Egg speciifie gravity
PM
M
PM
64.9 12.8 12.6
(Experiment 1) 63.8a 63.4a 72.1b 63.4a 71.4b 63.8a
60.0a 62.7b 60.7a
1.080a 1.080a 1.077a
1.073a 1.078b 1.073a
62.1 11.9 12.1
(Experiment 2) 51.4a 61.4a 61.2b 61.6a 57.5b 62.8b
61.3a 65.4b 62.7a
1.075a 1.076a 1.076a
1.076a 1.086c 1.081b
1 Means without common letters 2 M = Molt (6 weeks). 3 PM = Post Molt (24 weeks). 4
PE = Pre-Experiment.
Egg weight (g.) PE 4
in the same column are significantly different (P < .05).
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A marked reduction in feed intake occurred within the first 24 hours with hens fed the low salt diet. After 10 days, feed intake had decreased to 40% of the controls. The hens receiving the low salt diet during the six-week molt period consumed 63.5 and 56.5 grams per hen per day in Experiment 1 and 2, respectively (Table 2). This was a considerable reduction when compared to the controls and was slightly lower consumption than the hens molted on the procedure as outlined by Wilson et al. (1969). When the hens were returned to the diet containing salt, feed intake increased immediately, and during the post-molt period no significant differences between treatments could be detected.
After the hens had been receiving the low salt diet for three weeks, they had lost approximately 20% of their body weight (Table 2). Within three weeks (9th week of experiment) after returning the hens to the diet containing salt, they had regained body weight equal to controls. At the end of the experiment, there were no significant differences among body weights of hens on either of the three treatments. There was a slight reduction in body weight of all hens during the experimental period which possibly was due to the high environmental temperature. Hens fed the low dietary salt had a reduction in ovary and oviduct weights (Table 3). However, after the hens had been receiving the low dietary salt for 42 days, some hens still had ovaries and oviducts similar in weight to those of control hens. These ovaries had large follicles which were apparently mature and near the stage of ovulation. Egg production was reduced to less than 3% after the hens had been receiving the
2378
W. G. NESBETH, C. R. DOUGLAS AND R. H. HARMS
There was no significant difference in specific gravity of eggs among the three treatments during the molt period (Table 4). However, specific gravity of eggs from hens force rested by feeding the low dietary salt was significantly higher in both experiments than eggs from either the control group or hens force molted by the conventional method. Force molting the hens with a conventional method resulted in significantly improving egg specific gravity in Experiment 2, however, there was no beneficial affects in Experiment 1. In both experiments, some of the hens fed the low salt diet started to molt by the 13th day; however, most of the birds ceased production and did not molt. All hens appeared normal throughout the experiment and there was no excessive mortality on any of the treatments. The data in this paper indicate that hens can be fed a diet containing low salt which will result in a cessation of egg production.
This finding agrees with previous reports by Whitehead and Shannon (1974) and Nesbeth et al. (1976). It would appear that this method of force resting would be preferred over previously recommended methods of force resting. The use of low dietary salt could initiate a pause in egg production and would be preferred over feeding a low dietary calcium, since feeding the low dietary salt does not result in a depletion of calcium from the skeleton. The feeding of the low dietary salt resulted in egg production equal to that of hens molted by the method suggested by Wilson et al. (1969) and egg shell quality was better with hens rested on this program. Hens fed the low dietary salt did not appear to be under any stress; therefore, this method could be adapted for use in commercial egg production without any apparent problems. When low dietary levels of salt are used for force resting of hens, attention should be given to the dietary sodium level as well as the level of sodium in the drinking water. In this experiment, the diet and drinking water contained 270 and 26 p.p.m. of sodium, respectively. REFERENCES Adams, J. L., 1955. Progesterone-induced unseasonable molt in Single Comb White Leghorn pullets. Poultry Sci. 34: 702-707. Adams, J. L., 1956. A comparison of different methods of progesterone administration to the fowl in affecting egg production and molt. Poultry Sci. 35: 323326. Arrington, L. R., R. Santa-Cruz, R. H. Harms and H. R. Wilson, 1967. Effects of excess dietary iodine upon pullets and hens. J. Nutr. 92: 325-330. Bell, D., 1967. Characteristics of force-molted flocks. Feedstuffs, 39(26):21. Berg, L. R., and G. E. Bearse, 1947. Changes in egg quality from force molting White Leghorn yearling hens. Poultry Sci. 26: 414-418. Blair, R., and A. B. Gilbert, 1973. The influence of supplemental phosphorus in a low-calcium diet designed to induce a resting phase in laying hens. Br. Poultry Sci. 14: 131-135. Bundle, E., 1974. Extent of future molting depends on many factors. Feedstuffs, 46(46): 18, 20.
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low salt diet for three weeks. However, some of the birds continued to lay a few eggs during the molt period. This resulted in egg production being reduced to approximately 12% during the molt period (Table 4). The hens force molted according to the procedure of Wilson et al. (1969) had a rate of lay comparable to that of birds on low salt during the six weeks molt period. The hens on the low salt treatment began to increase in egg production after they had been returned to the diet containing salt for 12 days. Egg production was significantly increased during the post-molt period by both resting procedures. There was no significant difference between the two methods of resting. Eggs were significantly heavier during the post-molt period when hens were force rested by feeding the low dietary salt (Table 4). There was no significant difference in egg weights between the control hens and hens force molted according to the procedure of Wilson et al. (1969).
2379
SALT DEFICIENCY AND FORCE RESTING
1976. Response of laying hens to a low salt diet. Poultry Sci. 55: 000-000. Perdomo, J. T., R. H. Harms and L. R. Arrington, 1966. Effect of dietary iodine upon egg production, fertility and hatchability. Proc. Soc. Exp. Biol. Med. 122: 758-760. Shaffner, C. S., 1955. Progesterone induced molt. Poultry Sci. 34: 840-842. Snyder, E. S., and H. L. Orr, 1960. The effect of length of lay, holding temperature, holding time and forced molting on egg quality. Poultry Sci. 39: 1297. Whitehead, C. C , and D. W. F. Shannon, 1974. The control of egg production using a low sodium diet. Br. Poultry Sci. 15: 429-434. Wilson, H. R., J. S. Moore, A. W. O'Steen, J. L. Fry and R. H. Harms, 1969. Force molting of laying hens. Florida Exp. Sta. Bui. 728.
The Arginine Requirement of the 4-7 Week Old Broilerl J. W.
KESSLER AND O.
P. THOMAS
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication March 22, 1976)
ABSTRACT Two floor pen studies were conducted to determine the minimum arginine level needed to support maximum weight gain and optimum feed conversion during the 4-7 week period of growth for both males and females. Floor feather counts were used as an additional criteria for determining the arginine requirement. The basal diets were calculated to contain 0.74 and 0.80% arginine based on the analyzed values for corn, corn gluten meal, skimmilk and soybean meal. Regression equations were calculated from the data obtained for the males only. Based on the regression equations, the calculated requirement for maximum weight gain, optimum feed conversion, and floor feathers is 1.09, 1.10, and 1.13% arginine, respectively. When expressed as a function of energy, these requirements would be 0.329, 0.332, and 0.341% arginine per megacalorie of metabolizable energy per kg. of diet, respectively. The differences in rate of gain data for the females were non-significant, indicating the requirement of the females to be less than the males. The female requirement, based on floor feathers, would appear to be 0.98% dietary arginine. POULTRY SCIENCE 55: 2379-2382,
INTRODUCTION
R
E S E A R C H data indicating the arginine requirement of the 4 - 7 week old broiler could not b e f o u n d in t h e literature. C o m b s (1970) r e c o m m e n d s an amino acid-metabolizable energy ratio of 0.77 for arginine in broiler rations during the 5-8 week period
1. Scientific Article No. A2198 Contribution No. 5176 of the Maryland Agricultural Experiment Station (Department of Poultry Science).
1976
of growth. This ratio relates to m o d e r a t e environmental t e m p e r a t u r e conditions and should be increased by 5 to 10% for s u m m e r feeding conditions w h e r e hot weather is e x p e c t e d . T h e National A c a d e m y of Sciences (1971) lists the arginine requirement of t h e broiler for the 0-6 w e e k period of growth t o be 1.40% of the diet and 1.20% for the 6-9 week period. T h o m a s et al. (1975) revised t h e tables published by C o m b s (1970). H o w e v e r , the revisions m a d e did not c h a n g e the r e c o m m e n d e d value for arginine during
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Douglas, C. R., R. H. Harms and H. R. Wilson, 1972. The use of extremely low dietary calcium to alter the production pattern of laying hens. Poultry Sci. 51:2015-2020. Hansen, R. S., 1960. The effect of methods of force molting on reproductive performance of chickens. Poultry Sci. 39: 1257. Himeno, K., and Y. Tanabe, 1957. Mechanism of molting in the hen. Poultry Sci. 36: 835-842. Len, R. E., H. Abplanalp and E. A. Johnson, 1964. Second year production of force molted hens in the California random sample test. Poultry Sci. 43: 638-646. Martin, G. A., T. B. Morris, M. H. Gahle and D. G. Harwood, 1973. Force molting by limiting calcium intake. Poultry Sci. 52: 2058. Nesbeth, W. G., C. R. Douglas and R. H. Harms,