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Sequential Effects of Restricted Feeding and Force-Molting on Laying Hen Performance
600
GAVORA, SPENCER, HARE AND MORSE
rescuable virus. J. Nat. Cane. Inst. 57: 865-872. Witter, R. L., 1976. Natural mechanisms of controlling
lymphotropic herpesvirus infection (Marek's disease) in the chicken. Cancer Research, 36: 681-687.
Sequential Effects of Restricted Feeding and Force-Molting on Laying Hen Performance J. D. SUMMERS AND S. LEESON
Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N/G 2W1 (Received for publication August 12. 1976)
ABSTRACT Laying birds were fed diets containing 15 or 17% crude protein either ad libitum, restricted to 100 g./bird/day or time-limit fed for 4 hours each day (8.00-10.00 and 14.30-16.30). Dietary protein level had no significantly (P s 0.05) effect on performance, while the full fed birds consumed significantly (P s 0.01) more feed, produced a greater number of heavier eggs and gained more body weight than restricted or time-limit fed birds. All birds were fed a 15 or 17% crude protein diet ad libitum, following a force-molting program induced by removal of feed and water for a specified time. Pre-molt feeding regime had no significant (P s 0.05) effect on mortality, or on the rate of cessation of egg production or return to 50% egg production during the molting period. During the post-molt laying cycle, birds that had previously been restricted or time-limit fed, showed significant (P < 0.05) increases in egg size and body weight gain compared with those birds fed ad-libitum during the first laying cycle. Dietary protein level had no significant (P s 0.05) effect on production parameters during the post-molt period. Egg shell deformation and Haugh unit measurements were not significantly (P < 0.05) improved during the post-molt as compared with the pre-molt laying period. POULTRY SCIENCE 56: 600-604, 1977
INTRODUCTION
R
ESTRICTED feeding methods and force-molting procedures have received considerable attention in recent years as a means of reducing the cost of egg production. Since laying birds "overconsume" feed during the laying cycle, various methods for restricting daily nutrient intake have been proposed (Snetsinger and Zimmerman, 1974; Auckland and Wilson, 1975; Leeson and Summers, 1976; Balnave, 1976), while the economic and productive advantages of forced-molting, or the induction of a pause in lay subsequent to a second or third laying cycle have been well documented (Wilson et al., 1967; Polin and Wolford, 1972; Blair and Gilbert, 1973; Hurwitz et al., 1975; Gilbert and Blair 1975). There is little information available however on the effect of restricted feeding on the response of laying birds to a forced-molt. The following experiment was therefore designed to study the effect of restricted or
limit feeding regimes on the productive performance of force-molted birds. MATERIALS AND METHODS White Leghorn cross-strain pullets were housed at 18 weeks of age, with 2 birds per 25.5 cm cage. Each experimental replicate consisted of 8 cages equipped with a common feed trough. All birds were fed a commercial pullet growing diet till 21 weeks of age, at which time a 17% crude protein commercial laying diet was introduced and fed up to 26 weeks of age. At this time 6 experimental treatments were each randomly allotted to 4 replicate groups of 16 birds. These treatments consisted of two isocaloric diets providing 15 or 17% crude protein (Table 1) being fed either ad libitum, restricted fed to 100 g. / bird /day or being limit fed for 4 hours each day (8.00-10.00 and 14.3016.30). All birds were subjected to a 14 hour light period (5.00-19.00). Feed consumption was recorded for each
RESTRICTED FEEDING AND FORCE-MOLTING TABLE 1.—Percentage composition of
experimental diets Ingredient Ground yellow corn Soybean meal (49% protein) Tallow (stabilized) Ground limestone Calcium phosphate (20%P) Iodized salt (0.015% KI) Vitamin mix 1 Mineral mix2 Alpha floe Total Calculated analysis Crude protein (%) Metabolizable energy (kcal./kg.) Crude fat (%) Crude fiber (%) Calcium (%) Available phosphorus (%) Methionine (%) Cystine (%) Lysine (%) Arginine (%) Tryptophan (%) Threonine (%)
15%
i7%~
70.50 18.25 0.50 7.25 2.00 0.25 0.50 0.25 0.50
65.50 23.25 1.00 7.25 2.00 0.25 0.50 0.25
100.00
100.00
15.2
17.3
2852 3.3 2.8 3.2 0.5 0.27 0.22 0.73 0.94 0.20 0.65
2852 3.6 2.3 3.2 0.5 0.29 0.25 0.88 1.10 0.23 0.73
—
'Added per kg. diet: vitamin A, 8,000 I.U.; vitamin D 3 , 1600 I.U.; vitamin E, 11 I.U.; riboflavin, 7 mg.; pantothenic acid, 7 mg.; vitamin B 12 , 8 (jLg.; niacin, 20 mg.; choline, 900 mg.; vitamin K, 1.5 mg.; folic acid, 1.5 mg.; biotin, 0.25 mg.; santoquin, 125 mg. 2 Added per kg. diet: manganese, 55 mg.; zinc, 50 mg.; copper, 5 mg.; iron, 30 mg.
replicate group of birds during 8, 28 day periods, whilst egg weight, egg shell deformation, albumen height and Haugh unit measurements were ascertained from all eggs collected during the last 3 days of each period. At the end of the first laying cycle, birds were force-molted by removing feed and water for 3 days followed by a further 7 days in which only water was offered. Two replicate groups of 16 birds from each of the six original treatments were then offered the original diets providing 15 or 17% crude protein (Table 1). At this time, and during
601
the second laying cycle, all birds were offered feed ad libitum. Some 49 days after initiation of the forcedmolt, when egg production had reached 50%, measurement of production parameters similar to those detailed in the first laying cycle were started. RESULTS AND DISCUSSION During the first laying cycle, dietary protein level had no significant (P s 0.05) effect on any of the production parameters measured (Table 2). Feeding method however influenced all parameters except egg shell quality measurements (Table 2). Thus full-fed birds consumed more feed and produced a greater number of eggs which were of larger size (P •& 0.01) than birds on the restricted (100 g./bird/d.) or time-limit (4 hours/day) feeding regimes (Table 2). Time-limit fed birds consumed more feed and exhibited a higher rate of egg production than restricted fed birds, although these differences were not statistically significant (P s 0.05). The result of time limit versus control fed birds in terms of feed intake, egg production and egg weight are in agreement with the results of Polin and Wolford (1972). Body weight gain was also influenced by feeding method, where full fed birds constantly gained more weight during the first laying cycle, than restricted or time limit fed birds (Table 2). Weight gains for the restricted and time-limit fed birds was significantly (P < 0.01) different only at the end of the 4th period of lay (16 weeks), where time-limit fed birds exhibited a lower body weight gain (Table 2). During the forced-molt period, dietary protein level again had no significant (P < 0.05) effect on egg production or ad libitum feed intake (Table 3). It is possible that very low protein diets, as supplied by cereals alone, may extend the time that birds are put of lay (Wilson et a/., 1967). Pre-molt feeding regime also had no effect on egg production or feed
602
J. D. SUMMERS AND S. LEESON
TABLE 2.—Performance of White Leghorn pullets during the pre-molt laying cycle, as the mean of 8, 28 day periods
Treatment A. Protein level 15% protein 17% protein B. Feeding regime Full fed Restricted Limit fed A x B, Protein X feeding regime
(%)
Daily teed intake per bird (g.)
NS
Egg weight (g.)
Egg shell deformation ((xm.)
Albumen height (mm.)
Haugh units
4 wks.
16 wks.
30 wks.
NS
NS
NS
NS
NS
NS
NS
NS
77.2
103.6
59.2
24.3
6.1
76.0
369
422
526
77.4
102.8
59.7
25.2
6.1
76.1
394
431
532
**
**
** 60.8b
NS 75.9
**
110.9b
NS 6.1
**
79.6b
NS 24.1
* 408b
490b
626b
75.5a 76.8a
96.6a 102.0a
58.6a 58.9a
24.9 25.2
6.1 6.0
76.3 75.9
369a 368a
423a 365c
502a 459a
NS
NS
NS
NS
NS
NS
NS
NS
NS
Egg production
Body weight gaini (gm.)
*P<0.05, **P<0.01. NS = Non-significant. a Means bearing different small letters are significantly different at the level of probability shown. intake during the molting period, and rates of cessation and return, to 50% egg production were similar for all groups. Within 5 days of initiating the molting program, all birds had stopped laying (Table 3). During the second, post-molt, laying cycle, dietary protein level had no significant (P s 0.05) effect on any of the parameters measured (Table 4). Premolt feeding regime however had a significant effect on egg production and body weight gain. Although restricted and time limit-fed birds consumed similar quantities of feed as compared with full-fed birds, these former groups produced significantly (P s 0.05) more eggs (Table 4). The pre-molt restricted and time-limit fed birds also exhibited a greater weight gain in
the second laying cycle, this difference however being significant (P s 0.05) only for the time-limit-fed versus full fed birds (Table 4). Mortality throughout the entire experiment was not significantly (P < 0.5) affected by any of the dietary treatments, although there was an indication of increased mortality with the restricted fed group (Table 5). Mortality during the molting period was low for all groups of birds (Table 5) suggesting the molting procedure was not too severe. Egg weight increased significantly (P < 0.05) by almost 8 grams during the pre-molt period, while Haugh unit measurement showed a significant (P < 0.05) decrease and shell deformation a non-significant (P < 0.05)
TABLE 3.—Egg production and feed intake of White Leghorn pullets during the molting period Percentage egg production Dietary protein (%)
1
2
15 17
72.9a 64.3b
56.4 57.9
Days after initiation of molt 3 4 5 34.4 30.9
6.0 7.3
3.3 0.5
6-15
49
Average daily feed intake/ bird (g.) 11-49 days
0 0
53.7 49.5
105.4 106.0
603
RESTRICTED FEEDING AND FORCE-MOLTING
TABLE 4.—Performance of White Leghorn pullets fed ad libitum during the post-molt laying cycle, as the mean of 9, 28 day periods Daily feed intake per bird (g.) NS 102.8 103.2
Egg weight (g-) NS 64.5 64.5
61.9b 68.4a 66.6a
*
NS 100.7 105.6 102.8
NS 64.9 64.2 64.1
NS 25.3 25.1 25.9
NS
NS
NS
NS
Egg production Treatment A. Protein level 15% protein 17% protein B. Pre-molt feeding regime Full fed Restricted Limit fed A x B, Protein x feeding regime
(%) NS 66.1 65.2
Egg shell deforAlbumen mation height (ixm.) (mm.) NS NS 25.1 5.2 25.8 5.4
Hough units NS 67.8 68.9
Body weight gain (g.) NS 172 189
NS 5.3 5.2 5.4
NS 68.1 67.8 69.1
145b 173ab 222a
NS
NS
NS
*
*P==0.05. NS = Non-significant. "Means bearing different small letters are significantly different at the level of probability shown. TABLE 5.—Mortality (numbers of birds) Dietary protein 1 (%) Pre-molt feeding regime 1 Full-fed Restricted Limit-fed Total
Pre-molt 4 5 2
15 Molt 1 2 0
17 Post-molt
Pre-molt
Molt
Post-molt
Total
2 5 3
3 3 2
1 2 0
2 3 4
13 20 11
20
24
1
64 birds were started for each of the 6 experimental treatments.
decrease during this period (Table 6). Increase in egg weight was much smaller during the post-molt periods (Table 6). One of the advantages often suggested for a period of force-molting, is subsequent improvement in egg quality. Thus Hurwitz et al. (1975) described an improvement in shell weight per unit of surface area following a forced molting program, while Summers and Leeson (1976) showed an improvement in both shell deformation and albumen quality measurements immediately following a pause in lay induced by water deprivation. Whilst there was an indication that shell deformation values were improved immediately following the molt, subsequent values showed a gradual deterioration, and by the end of the post-molt period values were higher than at any other time during the experiment (Table 6). None of these shell deformation values were signif-
icantly (P £ 0.05) different however. Similarly, internal egg quality as assessed by Haugh unit measurement was not significantly (P < 0.05) improved during the post-molt period (Table 6). Wilson et al. (1967) similarly showed no improvement in albumen quality as a result of force-molting, and that shell thickness was increased in only 1 of 3 experiments. TABLE 6.—Effect of age of bird and force-molting on egg quality measurements
Pre-molt Period 1 Pre-molt Period 8 Post-molt Period 1 Post-molt Period 9
Av. egg weight (g.) 54.8a 62.5b 64.0c 65.2d
Egg shell deformation dun-) 23.3a 24.8a 23.9a 25.5a
Haugh units 84.5c 76.1b 76.8b 71.5a
a Means within each column bearing different small letters are significantly different (P < 0.05).
604
J. D . SUMMERS AND S. LEESON
T h e present study suggests that a marked saving in feed intake, with concomitant decrease in body weight gain can b e achieved either by manually restricting the quantity of feed presented t o the bird, or by limiting the time that birds h a v e access to the feed. Such a practice often results in reduced egg weight (Table 2), unless dietary changes are made in an a t t e m p t to counteract this effect (Snetsinger a n d Z i m m e r m a n , 1974). With any feeding program that limits feed intake, the results obtained are usually a direct reflection of absolute nutrient intake. H e n c e the results from a study such as this, must be interpreted in terms of nutrient intake rather than dietary composition. T h e p r e s e n t results also d e m o n s t r a t e that birds that have been restricted or limit fed are more suited in terms of egg production to a second laying cycle following a forcedmolt. ACKNOWLEDGEMENTS T h e authors acknowledge t h e
financial
support of the Ontario Ministry of Agriculture and Food in conduct of this work. REFERENCES Auckland, J. N., and S. B. Wilson, 1975. Effects
of restricting the amounts of medium or low-energy diets fed to laying hens in different colony sizes. Br. Poultry Sci. 16: 453-459. Balnave, D. 1976. The effect of low-protein grower diets on the subsequent response of pullets to quantitative food restriction during lay. Br. Poultry Sci. 17: 145-150. 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. Poult. Sci. 14: 131-135. Gilbert, A. B., and R. Blair, 1975. A comparison of the effects of two low calcium diets on egg production in the domestic fowl. Br. Poultry Sci. 16: 547-552. Hurwitz, S., S. Bornstein and Y. Lev, 1975. Some responses of laying hens to induced arrest of egg production. Poultry Sci. 54: 415-422. Leeson, S., and J. D. Summers, 1976. Voluntary feed intake restriction by the laying fowl. Proc. 1976 Univ. Guelph Nutr. Conf. 84-90. Polin, D., and J. H. Wolford, 1972. The effect of meal-eating on egg production and body weight of White Leghorn chickens. Poultry Sci. 51: 1109-1118. Snetsinger, D. C , and R. A. Zimmerman, 1974. In: Energy Requirements of Poultry. Ed. T. R. Morris and B. M. Freeman. Br. Poultry Sci., Ltd. Edinburgh: 185-199. Summers, J. D., and S. Leeson, 1976. Effect of water deprivation on egg production and egg quality. Poultry Sci. 55: 441-444. Wilson, H. R., J. L. Fry, R. H. Harms and L. R. Arrington, 1967. Performance of hens molted by various methods. Poultry Sci. 46: 1406-1412.
NEWS AND NOTES (Continued from page 589) F.D.A. NOTES Friends of Dr. J. C. Fritz will be glad to learn that he is slowly recovering from a foot bone infection, a possible sequela of his heart surgery several months ago. This condition developed after he returned to work in the Nutritional Sciences Branch. AMERICAN EGG BOARD The National Egg Board established by the Egg Research and Promotion Order became the American Egg Board beginning July 9, 1976, according to John Wallace, Chairman.
The use of the name, staff, offices, and assets of the American Egg Board were transferred to the National Egg Board as part of an agreement between the two groups. The main office of the new American Egg Board will remain at 205 Touhy Ave., Park Ridge, Illinois 60068. The telephone number also will be the same: 312/696-1390. A 25-minute presentation describing the new American Egg Board is now available for egg industry meetings. It explains AEB's programs for advertising, consumer education, and research. It also highlights
(Continued on page 614)
GAVORA, SPENCER, HARE AND MORSE
rescuable virus. J. Nat. Cane. Inst. 57: 865-872. Witter, R. L., 1976. Natural mechanisms of controlling
lymphotropic herpesvirus infection (Marek's disease) in the chicken. Cancer Research, 36: 681-687.
Sequential Effects of Restricted Feeding and Force-Molting on Laying Hen Performance J. D. SUMMERS AND S. LEESON
Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N/G 2W1 (Received for publication August 12. 1976)
ABSTRACT Laying birds were fed diets containing 15 or 17% crude protein either ad libitum, restricted to 100 g./bird/day or time-limit fed for 4 hours each day (8.00-10.00 and 14.30-16.30). Dietary protein level had no significantly (P s 0.05) effect on performance, while the full fed birds consumed significantly (P s 0.01) more feed, produced a greater number of heavier eggs and gained more body weight than restricted or time-limit fed birds. All birds were fed a 15 or 17% crude protein diet ad libitum, following a force-molting program induced by removal of feed and water for a specified time. Pre-molt feeding regime had no significant (P s 0.05) effect on mortality, or on the rate of cessation of egg production or return to 50% egg production during the molting period. During the post-molt laying cycle, birds that had previously been restricted or time-limit fed, showed significant (P < 0.05) increases in egg size and body weight gain compared with those birds fed ad-libitum during the first laying cycle. Dietary protein level had no significant (P s 0.05) effect on production parameters during the post-molt period. Egg shell deformation and Haugh unit measurements were not significantly (P < 0.05) improved during the post-molt as compared with the pre-molt laying period. POULTRY SCIENCE 56: 600-604, 1977
INTRODUCTION
R
ESTRICTED feeding methods and force-molting procedures have received considerable attention in recent years as a means of reducing the cost of egg production. Since laying birds "overconsume" feed during the laying cycle, various methods for restricting daily nutrient intake have been proposed (Snetsinger and Zimmerman, 1974; Auckland and Wilson, 1975; Leeson and Summers, 1976; Balnave, 1976), while the economic and productive advantages of forced-molting, or the induction of a pause in lay subsequent to a second or third laying cycle have been well documented (Wilson et al., 1967; Polin and Wolford, 1972; Blair and Gilbert, 1973; Hurwitz et al., 1975; Gilbert and Blair 1975). There is little information available however on the effect of restricted feeding on the response of laying birds to a forced-molt. The following experiment was therefore designed to study the effect of restricted or
limit feeding regimes on the productive performance of force-molted birds. MATERIALS AND METHODS White Leghorn cross-strain pullets were housed at 18 weeks of age, with 2 birds per 25.5 cm cage. Each experimental replicate consisted of 8 cages equipped with a common feed trough. All birds were fed a commercial pullet growing diet till 21 weeks of age, at which time a 17% crude protein commercial laying diet was introduced and fed up to 26 weeks of age. At this time 6 experimental treatments were each randomly allotted to 4 replicate groups of 16 birds. These treatments consisted of two isocaloric diets providing 15 or 17% crude protein (Table 1) being fed either ad libitum, restricted fed to 100 g. / bird /day or being limit fed for 4 hours each day (8.00-10.00 and 14.3016.30). All birds were subjected to a 14 hour light period (5.00-19.00). Feed consumption was recorded for each
RESTRICTED FEEDING AND FORCE-MOLTING TABLE 1.—Percentage composition of
experimental diets Ingredient Ground yellow corn Soybean meal (49% protein) Tallow (stabilized) Ground limestone Calcium phosphate (20%P) Iodized salt (0.015% KI) Vitamin mix 1 Mineral mix2 Alpha floe Total Calculated analysis Crude protein (%) Metabolizable energy (kcal./kg.) Crude fat (%) Crude fiber (%) Calcium (%) Available phosphorus (%) Methionine (%) Cystine (%) Lysine (%) Arginine (%) Tryptophan (%) Threonine (%)
15%
i7%~
70.50 18.25 0.50 7.25 2.00 0.25 0.50 0.25 0.50
65.50 23.25 1.00 7.25 2.00 0.25 0.50 0.25
100.00
100.00
15.2
17.3
2852 3.3 2.8 3.2 0.5 0.27 0.22 0.73 0.94 0.20 0.65
2852 3.6 2.3 3.2 0.5 0.29 0.25 0.88 1.10 0.23 0.73
—
'Added per kg. diet: vitamin A, 8,000 I.U.; vitamin D 3 , 1600 I.U.; vitamin E, 11 I.U.; riboflavin, 7 mg.; pantothenic acid, 7 mg.; vitamin B 12 , 8 (jLg.; niacin, 20 mg.; choline, 900 mg.; vitamin K, 1.5 mg.; folic acid, 1.5 mg.; biotin, 0.25 mg.; santoquin, 125 mg. 2 Added per kg. diet: manganese, 55 mg.; zinc, 50 mg.; copper, 5 mg.; iron, 30 mg.
replicate group of birds during 8, 28 day periods, whilst egg weight, egg shell deformation, albumen height and Haugh unit measurements were ascertained from all eggs collected during the last 3 days of each period. At the end of the first laying cycle, birds were force-molted by removing feed and water for 3 days followed by a further 7 days in which only water was offered. Two replicate groups of 16 birds from each of the six original treatments were then offered the original diets providing 15 or 17% crude protein (Table 1). At this time, and during
601
the second laying cycle, all birds were offered feed ad libitum. Some 49 days after initiation of the forcedmolt, when egg production had reached 50%, measurement of production parameters similar to those detailed in the first laying cycle were started. RESULTS AND DISCUSSION During the first laying cycle, dietary protein level had no significant (P s 0.05) effect on any of the production parameters measured (Table 2). Feeding method however influenced all parameters except egg shell quality measurements (Table 2). Thus full-fed birds consumed more feed and produced a greater number of eggs which were of larger size (P •& 0.01) than birds on the restricted (100 g./bird/d.) or time-limit (4 hours/day) feeding regimes (Table 2). Time-limit fed birds consumed more feed and exhibited a higher rate of egg production than restricted fed birds, although these differences were not statistically significant (P s 0.05). The result of time limit versus control fed birds in terms of feed intake, egg production and egg weight are in agreement with the results of Polin and Wolford (1972). Body weight gain was also influenced by feeding method, where full fed birds constantly gained more weight during the first laying cycle, than restricted or time limit fed birds (Table 2). Weight gains for the restricted and time-limit fed birds was significantly (P < 0.01) different only at the end of the 4th period of lay (16 weeks), where time-limit fed birds exhibited a lower body weight gain (Table 2). During the forced-molt period, dietary protein level again had no significant (P < 0.05) effect on egg production or ad libitum feed intake (Table 3). It is possible that very low protein diets, as supplied by cereals alone, may extend the time that birds are put of lay (Wilson et a/., 1967). Pre-molt feeding regime also had no effect on egg production or feed
602
J. D. SUMMERS AND S. LEESON
TABLE 2.—Performance of White Leghorn pullets during the pre-molt laying cycle, as the mean of 8, 28 day periods
Treatment A. Protein level 15% protein 17% protein B. Feeding regime Full fed Restricted Limit fed A x B, Protein X feeding regime
(%)
Daily teed intake per bird (g.)
NS
Egg weight (g.)
Egg shell deformation ((xm.)
Albumen height (mm.)
Haugh units
4 wks.
16 wks.
30 wks.
NS
NS
NS
NS
NS
NS
NS
NS
77.2
103.6
59.2
24.3
6.1
76.0
369
422
526
77.4
102.8
59.7
25.2
6.1
76.1
394
431
532
**
**
** 60.8b
NS 75.9
**
110.9b
NS 6.1
**
79.6b
NS 24.1
* 408b
490b
626b
75.5a 76.8a
96.6a 102.0a
58.6a 58.9a
24.9 25.2
6.1 6.0
76.3 75.9
369a 368a
423a 365c
502a 459a
NS
NS
NS
NS
NS
NS
NS
NS
NS
Egg production
Body weight gaini (gm.)
*P<0.05, **P<0.01. NS = Non-significant. a Means bearing different small letters are significantly different at the level of probability shown. intake during the molting period, and rates of cessation and return, to 50% egg production were similar for all groups. Within 5 days of initiating the molting program, all birds had stopped laying (Table 3). During the second, post-molt, laying cycle, dietary protein level had no significant (P s 0.05) effect on any of the parameters measured (Table 4). Premolt feeding regime however had a significant effect on egg production and body weight gain. Although restricted and time limit-fed birds consumed similar quantities of feed as compared with full-fed birds, these former groups produced significantly (P s 0.05) more eggs (Table 4). The pre-molt restricted and time-limit fed birds also exhibited a greater weight gain in
the second laying cycle, this difference however being significant (P s 0.05) only for the time-limit-fed versus full fed birds (Table 4). Mortality throughout the entire experiment was not significantly (P < 0.5) affected by any of the dietary treatments, although there was an indication of increased mortality with the restricted fed group (Table 5). Mortality during the molting period was low for all groups of birds (Table 5) suggesting the molting procedure was not too severe. Egg weight increased significantly (P < 0.05) by almost 8 grams during the pre-molt period, while Haugh unit measurement showed a significant (P < 0.05) decrease and shell deformation a non-significant (P < 0.05)
TABLE 3.—Egg production and feed intake of White Leghorn pullets during the molting period Percentage egg production Dietary protein (%)
1
2
15 17
72.9a 64.3b
56.4 57.9
Days after initiation of molt 3 4 5 34.4 30.9
6.0 7.3
3.3 0.5
6-15
49
Average daily feed intake/ bird (g.) 11-49 days
0 0
53.7 49.5
105.4 106.0
603
RESTRICTED FEEDING AND FORCE-MOLTING
TABLE 4.—Performance of White Leghorn pullets fed ad libitum during the post-molt laying cycle, as the mean of 9, 28 day periods Daily feed intake per bird (g.) NS 102.8 103.2
Egg weight (g-) NS 64.5 64.5
61.9b 68.4a 66.6a
*
NS 100.7 105.6 102.8
NS 64.9 64.2 64.1
NS 25.3 25.1 25.9
NS
NS
NS
NS
Egg production Treatment A. Protein level 15% protein 17% protein B. Pre-molt feeding regime Full fed Restricted Limit fed A x B, Protein x feeding regime
(%) NS 66.1 65.2
Egg shell deforAlbumen mation height (ixm.) (mm.) NS NS 25.1 5.2 25.8 5.4
Hough units NS 67.8 68.9
Body weight gain (g.) NS 172 189
NS 5.3 5.2 5.4
NS 68.1 67.8 69.1
145b 173ab 222a
NS
NS
NS
*
*P==0.05. NS = Non-significant. "Means bearing different small letters are significantly different at the level of probability shown. TABLE 5.—Mortality (numbers of birds) Dietary protein 1 (%) Pre-molt feeding regime 1 Full-fed Restricted Limit-fed Total
Pre-molt 4 5 2
15 Molt 1 2 0
17 Post-molt
Pre-molt
Molt
Post-molt
Total
2 5 3
3 3 2
1 2 0
2 3 4
13 20 11
20
24
1
64 birds were started for each of the 6 experimental treatments.
decrease during this period (Table 6). Increase in egg weight was much smaller during the post-molt periods (Table 6). One of the advantages often suggested for a period of force-molting, is subsequent improvement in egg quality. Thus Hurwitz et al. (1975) described an improvement in shell weight per unit of surface area following a forced molting program, while Summers and Leeson (1976) showed an improvement in both shell deformation and albumen quality measurements immediately following a pause in lay induced by water deprivation. Whilst there was an indication that shell deformation values were improved immediately following the molt, subsequent values showed a gradual deterioration, and by the end of the post-molt period values were higher than at any other time during the experiment (Table 6). None of these shell deformation values were signif-
icantly (P £ 0.05) different however. Similarly, internal egg quality as assessed by Haugh unit measurement was not significantly (P < 0.05) improved during the post-molt period (Table 6). Wilson et al. (1967) similarly showed no improvement in albumen quality as a result of force-molting, and that shell thickness was increased in only 1 of 3 experiments. TABLE 6.—Effect of age of bird and force-molting on egg quality measurements
Pre-molt Period 1 Pre-molt Period 8 Post-molt Period 1 Post-molt Period 9
Av. egg weight (g.) 54.8a 62.5b 64.0c 65.2d
Egg shell deformation dun-) 23.3a 24.8a 23.9a 25.5a
Haugh units 84.5c 76.1b 76.8b 71.5a
a Means within each column bearing different small letters are significantly different (P < 0.05).
604
J. D . SUMMERS AND S. LEESON
T h e present study suggests that a marked saving in feed intake, with concomitant decrease in body weight gain can b e achieved either by manually restricting the quantity of feed presented t o the bird, or by limiting the time that birds h a v e access to the feed. Such a practice often results in reduced egg weight (Table 2), unless dietary changes are made in an a t t e m p t to counteract this effect (Snetsinger a n d Z i m m e r m a n , 1974). With any feeding program that limits feed intake, the results obtained are usually a direct reflection of absolute nutrient intake. H e n c e the results from a study such as this, must be interpreted in terms of nutrient intake rather than dietary composition. T h e p r e s e n t results also d e m o n s t r a t e that birds that have been restricted or limit fed are more suited in terms of egg production to a second laying cycle following a forcedmolt. ACKNOWLEDGEMENTS T h e authors acknowledge t h e
financial
support of the Ontario Ministry of Agriculture and Food in conduct of this work. REFERENCES Auckland, J. N., and S. B. Wilson, 1975. Effects
of restricting the amounts of medium or low-energy diets fed to laying hens in different colony sizes. Br. Poultry Sci. 16: 453-459. Balnave, D. 1976. The effect of low-protein grower diets on the subsequent response of pullets to quantitative food restriction during lay. Br. Poultry Sci. 17: 145-150. 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. Poult. Sci. 14: 131-135. Gilbert, A. B., and R. Blair, 1975. A comparison of the effects of two low calcium diets on egg production in the domestic fowl. Br. Poultry Sci. 16: 547-552. Hurwitz, S., S. Bornstein and Y. Lev, 1975. Some responses of laying hens to induced arrest of egg production. Poultry Sci. 54: 415-422. Leeson, S., and J. D. Summers, 1976. Voluntary feed intake restriction by the laying fowl. Proc. 1976 Univ. Guelph Nutr. Conf. 84-90. Polin, D., and J. H. Wolford, 1972. The effect of meal-eating on egg production and body weight of White Leghorn chickens. Poultry Sci. 51: 1109-1118. Snetsinger, D. C , and R. A. Zimmerman, 1974. In: Energy Requirements of Poultry. Ed. T. R. Morris and B. M. Freeman. Br. Poultry Sci., Ltd. Edinburgh: 185-199. Summers, J. D., and S. Leeson, 1976. Effect of water deprivation on egg production and egg quality. Poultry Sci. 55: 441-444. Wilson, H. R., J. L. Fry, R. H. Harms and L. R. Arrington, 1967. Performance of hens molted by various methods. Poultry Sci. 46: 1406-1412.
NEWS AND NOTES (Continued from page 589) F.D.A. NOTES Friends of Dr. J. C. Fritz will be glad to learn that he is slowly recovering from a foot bone infection, a possible sequela of his heart surgery several months ago. This condition developed after he returned to work in the Nutritional Sciences Branch. AMERICAN EGG BOARD The National Egg Board established by the Egg Research and Promotion Order became the American Egg Board beginning July 9, 1976, according to John Wallace, Chairman.
The use of the name, staff, offices, and assets of the American Egg Board were transferred to the National Egg Board as part of an agreement between the two groups. The main office of the new American Egg Board will remain at 205 Touhy Ave., Park Ridge, Illinois 60068. The telephone number also will be the same: 312/696-1390. A 25-minute presentation describing the new American Egg Board is now available for egg industry meetings. It explains AEB's programs for advertising, consumer education, and research. It also highlights
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