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Effects of Temporary Feed Deprivation on Performance of Yearling Hens
Effects of Temporary Feed Deprivation on Performance of Yearling Hens P. C. LOWE and V. A. GARWOOD
US Department ofAgriculture, Agricultural Research Service, Purdue University, West Lafayette, Indiana 47907 (Received for publication March 23, 1982)
1982 Poultry Science 61:2157-2160 INTRODUCTION Temporary declines in the rate of lay have always been the concern of the egg producer. Causes are many including nutritional stress, diseases and parasites, environmental extremes, and deprivation of feed and water. Of major concern to the poultryman is the effect of temporary feed deprivation on egg production; they need to know whether any decline in production is temporary or permanent and whether recovery time is long or short. Swanson and Bell (1974) studied this problem when they compared feed withholding periods of 8, 10, and 12 days in yearling Leghorn hens and reported that postrecovery egg production tended to be higher for longer withholding periods. Bell (1967) reported field observations indicating that feed deprivation for 10 days resulted in higher postrecovery egg production than that of the continuously fed birds. Likewise, Safi and Miller (1969) found that adult birds on feed withdrawal returned to levels of production equal to controls in 28 days after resumption of full feed. The objectives of this study were to assess the effects of specific periods of short-term feed deprivation on egg production in yearling hens and to refine estimates of recovery time in terms of a return to normal egg production. Treatment effects on some traits correlated with egg production were also observed. MATERIALS AND METHODS Eight hundred White Leghorn hens 72 weeks
old were randomly selected from the NCR White Leghorn randombred population maintained at the North Central Regional Poultry Breeding Laboratory. Hens were then moved from floor pens to laying cages in August, 1980, and held on full feed for 1 week prior to the start of the experiment. Birds were placed 2 per cage in 400 cages of size 20 X 40 cm with 100 cages assigned to each of four treatments and with each cage defined as an experimental unit. Birds were fed a commercial laying ration prior to and immediately after the feed withholding periods. The lighting schedule remained a constant 14 hr of light a day before and during the experiment. Treatments were designated as 0 (control), 2, 4, and 6, indicative of the number of days birds were deprived of feed during the 1st week of the 25-week experiment. Egg production per cage was recorded for 3 consecutive days each week whereas mortality, egg and body weights, and egg specific gravity (based upon Archimede's principle) were measured at predetermined times during the experiment. Data within each weekly period were analyzed by one-way analysis of variance and differences among treatment means were tested for statistical significance by the StudentNewman-Kuels multiple range test (Steel and Torrie, 1960). The influence of units of time upon units of egg production was examined by the technique of linear regression. All tests for statistical significance were interpreted at the 5% probability level.
2157
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
ABSTRACT Four treatment groups each of 200 hens 72 weeks old were randomly selected from a randombred white Leghorn population. Treatment groups were deprived of feed for 0 (control), 2, 4, and 6 days during the 1st week of the 25-week experiment. Hens in Treatments 2, 4, and 6 had an immediate temporary decline in egg production, but their normal rate of lay was resumed after week 5 of the experiment. Losses in egg production during fasting and recovery were compensated for by higher rates of lay during the last 15 weeks of the experiment. Body and egg weights and mortality were unaffected by treatments; however, egg specific gravity was adversely affected at week 10 in treatments where egg production continued during feed deprivation. (Key words: feed deprivation, egg production, yearling hens)
LOWE AND GARWOOD
2158 RESULTS AND DISCUSSION
The effects of treatments on egg production, when it was measured as the cumulative average number of eggs by weeks for experimental units, are shown in Table 2. As a consequence of the treatments, cumulative averages at week 4 varied according to length of fast and all were significantly different from all others. One approximation of the time required for return to normal accumulated egg production after a specific fasting period is provided by the week of the experiment in which a given treatment level became statistically equal to that of the control. By this measure the normal average was regained in weeks 5, 9, and 13 for Treatments 2, 4, and 6, respectively. Perhaps a more practical measure of fasting recovery time would be provided for the egg producer by the period of time required for the cumulative
TABLE 1. Average hen-housed rate of lay for experimental units in weeks 1 to 5 by treatments Treatments (days of feed restriction) Week
0
2
4
1 2 3 4 5
51.4 47.6 47.3C 58.6C 55.9
50.4 48.5 34.2b 50.0 b 60.3
51.4 36.4 b 1.8a 43.4 a 58.8
' ' Row entries with different superscripts are statistically different (P<.05).
TABLE 2. Average cumulative number of eggs per experimental unit by weeks and treatment levels Treatment levels (days of feed restriction) Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
0
2
4
3.1 6.0 8.8
3.0 6.0 8.0
12.4d 15.8 18.8 21.9 24.8 28.0 30.7 33.8 36.7 39.9 43.0 46.4 49.7 52.7 55.9 59.1 62.2 65.6 68.7 71.0 73.3 75.4
11.1= 14.7 17.8 21.2 24.6 27.7 30.7 33.8 37.0 40.4 43.6 47.0 50.5 53.7 56.9 59.8 62.9 66.0 69.1 71.5 73.6 75.8
6 3.1 5.3
5.4b 8.0b 11.6b 14.8 b 18.2 b 21.4 b 25.0 28.7 32.0 35.3 39.1 43.0 47.1 50.9 54.5 57.9 61.2 64.7 68.3 71.7 74.3 77.0 79.7
2.4a 2.8a 2.8a 5.3a 8.5a 11.4a 14.4a 17.2a 20.8a 24.3a 28.1a 32.2a 36.1 40.5 44.7 48.9 52.7 56.5 60.0 64.1 68.0 71.9 75.0 78.5 81.2
' ' ' Row entries with different superscripts are statistically different (P<.05).
average number of eggs to equal or exceed (in absolute value) that of the control treatment. These values were reached in weeks 10, 14, and 17 for the three feed deprivation treatments of 2, 4, and 6 days. These relationships are shown graphically by the regression lines in Figure 1. Treatment 6 in Figure 1 is the only curve displaying significant curvilinearity. All deprivation groups exceeded controls in cumulative average numbers of eggs after week 17 (Table 2), but those differences among treatment means were not statistically significant. Although treatment means after week 17 did not reach the predetermined level of statistical significance, it is important to note that a trend developed toward larger differences in favor of the treatments with longer periods of feed deprivation. The probability of true differences among treatment means at week 25, a difference in favor of Treatments 4 and 6, was about .80 in this study. These differences are certainly of economic significance and indicate
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
The effects of treatments on hen-housed rate of lay during the initial part (first 5 weeks) of the experiment are shown in Table 1. Note that week 1 of the experiment is the week of feed withdrawal and that week 2 is the first week following feed withdrawal and so on. Moving the birds from floor pens to cages in hot weather apparently resulted in a temporary drop in rate of lay as reflected in the performance of Treatment 0. Although the stress from moving the birds is confounded with treatment effects, the contrasts between and among treatments remain valid as the control treatment (0) adequately measures environmental effects independently of treatment effects. Birds in Treatments 4 and 6, reflecting the severity of treatments, declined sharply in production during weeks 2 and 3 as compared to birds in Treatments 0 and 2.
FEED DEPRIVATION IN YEARLING HENS
/6 C.Z—CONTROL AMD TRERTnENT 2 4—TREATMENT 4 6—TRERTHENT 6
/y/*"2
64o §53o K is ts42UJ
> £3lJ O
9-
1
18 13 16 WEEKS OF ESG PRODUCTION
FIG. 1. Regression lines associating weeks and average accumulated number of eggs in four treatments.
that yearling hens of a light breed, when given enough time, are able to compensate for a temporary decline in egg production due to temporary feed deprivation. The suggestion is strong, therefore, that temporary egg production loss from feed deprivation results in a later surge of production more than enough to offset the earlier loss. The study reported here is not an attempt to evaluate standard force molting procedures but is concerned with the effects of temporary fasting periods in laying flocks. However, a close resemblance to results from force molting does appear from this study and the results parallel those of some reports. For example,
Nesbeth et al. (1976) reported that force molted birds had higher postmolt egg production than did controls. Rate of lay, a measure of production independent of mortality, peaked during the 4th month of the experiment (Table 3) at 76% for Treatment 6 and declined during the 5 th and 6th months. The peak rate of lay reported here occurred about 1 month later than that reported by Len et al. (1964); however, their study included heavy breeds and crosses as well as light breeds. The peak rate observed in the current study agrees well with that of Wilson et al. (1969) who reported a postmolt peak rate of lay of 75% for 1 month. Treatments had no effect on egg or body weights at 10 weeks after feed deprivation or on egg weight 20 weeks afterwards (Table 4). Mortality was not significantly different among treatments, varying from 10 to 11%. Eggshell strength as estimated by specific gravity mea-
TABLE 3. Percent hen-day rate of lay for experimental units by month and treatment Treatments Month
0
2
4
6
Avg.
1 2 3 4 5 6
52.8 53.4 52.1C 58.4 60.0 46.7
49.2 55.2 55.0 b c 60.4 55.3 46.5
38.9 b 57.1 60.6 b 67.6 62.0 52.3
28.9 D 54.0 69.6 a 76.0 a 70.1a 61.7
42.1 54.9 59.6 65.9 62.1 52.0
a ' 'cRow entries with different superscripts are statistically different (P<.05).
TABLE 4. Means for experimental units by treatments for traits associated with egg production Treatments Trait
Week
0
2
4
6
Egg weight (g) Body weight (kg) Specific gravity Egg weight (g) Specific gravity Mortality (%)
10 10 10 20 20
62.9 1.65 1.076 a 65.1 1.073 a 11.0
64.0 1.70 1.072 66.1 1.075 a b 11.0
63.7 1.72 1.070 65.6 1.075 ab 10.5
63.7 1.67 1.075 a 65.0 1.077 b 10.0
Row entries differing in superscripts are statistically different (P<.05).
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
20-
2159
2160
LOWE AND GARWOOD
REFERENCES Bell, D. D., 1967. Poultry scratch. Univ. California Agric. Circ. 425C. 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. Nesbeth, W. G., C. R. Douglas, and R. H. Harms, 1976. The potential use of dietary salt deficiency for the force resisting of laying hens. Poultry Sci. 55:2375-2379. Safi, L. M., and B. F. Miller, 1969. Inducing and controlling reproductive pauses in laying hens. Poultry Sci. 48:1865. (Abstr.) Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill, New York. Swanson, M. H., and D. D. Bell, 1974. Force molting of chickens. II. Methods. Univ. California Agric. Ext. Leaflet 2650. Wilson, H. R., J. S. Moore, A. W. O'Steen, J. L. Fry, and R. H. Harms, 1969. Forced molting of laying hens. Florida Agric. Exp. Sta. Bull. 728.
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
sured at 10 weeks after feed deprivation, was significantly higher for T r e a t m e n t s 0 and 6 t h a n for 2 and 4. A l t h o u g h these differences are statistically significant, their biological importance is minimal. T h e length of time necessary for recovery in laying hens t e m p o r a r i l y deprived of feed m a y be estimated b y various measures of egg prod u c t i o n , each leading to a s o m e w h a t different conclusion. T h e interval for r e s u m p t i o n of n o r m a l rate of lay is 4 t o 8 weeks in hens deprived of feed long enough t o cause cessation of lay. Recovery t o t h e e x t e n t of restoring, in a statistical sense, t h e n o r m a l a c c u m u l a t e d n u m b e r of eggs requires 5 to 13 weeks, d e p e n d ing on t h e length of t i m e w i t h o u t feed, and 1 0 t o 17 weeks in t e r m s of absolute n u m b e r s of eggs.
US Department ofAgriculture, Agricultural Research Service, Purdue University, West Lafayette, Indiana 47907 (Received for publication March 23, 1982)
1982 Poultry Science 61:2157-2160 INTRODUCTION Temporary declines in the rate of lay have always been the concern of the egg producer. Causes are many including nutritional stress, diseases and parasites, environmental extremes, and deprivation of feed and water. Of major concern to the poultryman is the effect of temporary feed deprivation on egg production; they need to know whether any decline in production is temporary or permanent and whether recovery time is long or short. Swanson and Bell (1974) studied this problem when they compared feed withholding periods of 8, 10, and 12 days in yearling Leghorn hens and reported that postrecovery egg production tended to be higher for longer withholding periods. Bell (1967) reported field observations indicating that feed deprivation for 10 days resulted in higher postrecovery egg production than that of the continuously fed birds. Likewise, Safi and Miller (1969) found that adult birds on feed withdrawal returned to levels of production equal to controls in 28 days after resumption of full feed. The objectives of this study were to assess the effects of specific periods of short-term feed deprivation on egg production in yearling hens and to refine estimates of recovery time in terms of a return to normal egg production. Treatment effects on some traits correlated with egg production were also observed. MATERIALS AND METHODS Eight hundred White Leghorn hens 72 weeks
old were randomly selected from the NCR White Leghorn randombred population maintained at the North Central Regional Poultry Breeding Laboratory. Hens were then moved from floor pens to laying cages in August, 1980, and held on full feed for 1 week prior to the start of the experiment. Birds were placed 2 per cage in 400 cages of size 20 X 40 cm with 100 cages assigned to each of four treatments and with each cage defined as an experimental unit. Birds were fed a commercial laying ration prior to and immediately after the feed withholding periods. The lighting schedule remained a constant 14 hr of light a day before and during the experiment. Treatments were designated as 0 (control), 2, 4, and 6, indicative of the number of days birds were deprived of feed during the 1st week of the 25-week experiment. Egg production per cage was recorded for 3 consecutive days each week whereas mortality, egg and body weights, and egg specific gravity (based upon Archimede's principle) were measured at predetermined times during the experiment. Data within each weekly period were analyzed by one-way analysis of variance and differences among treatment means were tested for statistical significance by the StudentNewman-Kuels multiple range test (Steel and Torrie, 1960). The influence of units of time upon units of egg production was examined by the technique of linear regression. All tests for statistical significance were interpreted at the 5% probability level.
2157
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
ABSTRACT Four treatment groups each of 200 hens 72 weeks old were randomly selected from a randombred white Leghorn population. Treatment groups were deprived of feed for 0 (control), 2, 4, and 6 days during the 1st week of the 25-week experiment. Hens in Treatments 2, 4, and 6 had an immediate temporary decline in egg production, but their normal rate of lay was resumed after week 5 of the experiment. Losses in egg production during fasting and recovery were compensated for by higher rates of lay during the last 15 weeks of the experiment. Body and egg weights and mortality were unaffected by treatments; however, egg specific gravity was adversely affected at week 10 in treatments where egg production continued during feed deprivation. (Key words: feed deprivation, egg production, yearling hens)
LOWE AND GARWOOD
2158 RESULTS AND DISCUSSION
The effects of treatments on egg production, when it was measured as the cumulative average number of eggs by weeks for experimental units, are shown in Table 2. As a consequence of the treatments, cumulative averages at week 4 varied according to length of fast and all were significantly different from all others. One approximation of the time required for return to normal accumulated egg production after a specific fasting period is provided by the week of the experiment in which a given treatment level became statistically equal to that of the control. By this measure the normal average was regained in weeks 5, 9, and 13 for Treatments 2, 4, and 6, respectively. Perhaps a more practical measure of fasting recovery time would be provided for the egg producer by the period of time required for the cumulative
TABLE 1. Average hen-housed rate of lay for experimental units in weeks 1 to 5 by treatments Treatments (days of feed restriction) Week
0
2
4
1 2 3 4 5
51.4 47.6 47.3C 58.6C 55.9
50.4 48.5 34.2b 50.0 b 60.3
51.4 36.4 b 1.8a 43.4 a 58.8
' ' Row entries with different superscripts are statistically different (P<.05).
TABLE 2. Average cumulative number of eggs per experimental unit by weeks and treatment levels Treatment levels (days of feed restriction) Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
0
2
4
3.1 6.0 8.8
3.0 6.0 8.0
12.4d 15.8 18.8 21.9 24.8 28.0 30.7 33.8 36.7 39.9 43.0 46.4 49.7 52.7 55.9 59.1 62.2 65.6 68.7 71.0 73.3 75.4
11.1= 14.7 17.8 21.2 24.6 27.7 30.7 33.8 37.0 40.4 43.6 47.0 50.5 53.7 56.9 59.8 62.9 66.0 69.1 71.5 73.6 75.8
6 3.1 5.3
5.4b 8.0b 11.6b 14.8 b 18.2 b 21.4 b 25.0 28.7 32.0 35.3 39.1 43.0 47.1 50.9 54.5 57.9 61.2 64.7 68.3 71.7 74.3 77.0 79.7
2.4a 2.8a 2.8a 5.3a 8.5a 11.4a 14.4a 17.2a 20.8a 24.3a 28.1a 32.2a 36.1 40.5 44.7 48.9 52.7 56.5 60.0 64.1 68.0 71.9 75.0 78.5 81.2
' ' ' Row entries with different superscripts are statistically different (P<.05).
average number of eggs to equal or exceed (in absolute value) that of the control treatment. These values were reached in weeks 10, 14, and 17 for the three feed deprivation treatments of 2, 4, and 6 days. These relationships are shown graphically by the regression lines in Figure 1. Treatment 6 in Figure 1 is the only curve displaying significant curvilinearity. All deprivation groups exceeded controls in cumulative average numbers of eggs after week 17 (Table 2), but those differences among treatment means were not statistically significant. Although treatment means after week 17 did not reach the predetermined level of statistical significance, it is important to note that a trend developed toward larger differences in favor of the treatments with longer periods of feed deprivation. The probability of true differences among treatment means at week 25, a difference in favor of Treatments 4 and 6, was about .80 in this study. These differences are certainly of economic significance and indicate
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
The effects of treatments on hen-housed rate of lay during the initial part (first 5 weeks) of the experiment are shown in Table 1. Note that week 1 of the experiment is the week of feed withdrawal and that week 2 is the first week following feed withdrawal and so on. Moving the birds from floor pens to cages in hot weather apparently resulted in a temporary drop in rate of lay as reflected in the performance of Treatment 0. Although the stress from moving the birds is confounded with treatment effects, the contrasts between and among treatments remain valid as the control treatment (0) adequately measures environmental effects independently of treatment effects. Birds in Treatments 4 and 6, reflecting the severity of treatments, declined sharply in production during weeks 2 and 3 as compared to birds in Treatments 0 and 2.
FEED DEPRIVATION IN YEARLING HENS
/6 C.Z—CONTROL AMD TRERTnENT 2 4—TREATMENT 4 6—TRERTHENT 6
/y/*"2
64o §53o K is ts42UJ
> £3lJ O
9-
1
18 13 16 WEEKS OF ESG PRODUCTION
FIG. 1. Regression lines associating weeks and average accumulated number of eggs in four treatments.
that yearling hens of a light breed, when given enough time, are able to compensate for a temporary decline in egg production due to temporary feed deprivation. The suggestion is strong, therefore, that temporary egg production loss from feed deprivation results in a later surge of production more than enough to offset the earlier loss. The study reported here is not an attempt to evaluate standard force molting procedures but is concerned with the effects of temporary fasting periods in laying flocks. However, a close resemblance to results from force molting does appear from this study and the results parallel those of some reports. For example,
Nesbeth et al. (1976) reported that force molted birds had higher postmolt egg production than did controls. Rate of lay, a measure of production independent of mortality, peaked during the 4th month of the experiment (Table 3) at 76% for Treatment 6 and declined during the 5 th and 6th months. The peak rate of lay reported here occurred about 1 month later than that reported by Len et al. (1964); however, their study included heavy breeds and crosses as well as light breeds. The peak rate observed in the current study agrees well with that of Wilson et al. (1969) who reported a postmolt peak rate of lay of 75% for 1 month. Treatments had no effect on egg or body weights at 10 weeks after feed deprivation or on egg weight 20 weeks afterwards (Table 4). Mortality was not significantly different among treatments, varying from 10 to 11%. Eggshell strength as estimated by specific gravity mea-
TABLE 3. Percent hen-day rate of lay for experimental units by month and treatment Treatments Month
0
2
4
6
Avg.
1 2 3 4 5 6
52.8 53.4 52.1C 58.4 60.0 46.7
49.2 55.2 55.0 b c 60.4 55.3 46.5
38.9 b 57.1 60.6 b 67.6 62.0 52.3
28.9 D 54.0 69.6 a 76.0 a 70.1a 61.7
42.1 54.9 59.6 65.9 62.1 52.0
a ' 'cRow entries with different superscripts are statistically different (P<.05).
TABLE 4. Means for experimental units by treatments for traits associated with egg production Treatments Trait
Week
0
2
4
6
Egg weight (g) Body weight (kg) Specific gravity Egg weight (g) Specific gravity Mortality (%)
10 10 10 20 20
62.9 1.65 1.076 a 65.1 1.073 a 11.0
64.0 1.70 1.072 66.1 1.075 a b 11.0
63.7 1.72 1.070 65.6 1.075 ab 10.5
63.7 1.67 1.075 a 65.0 1.077 b 10.0
Row entries differing in superscripts are statistically different (P<.05).
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
20-
2159
2160
LOWE AND GARWOOD
REFERENCES Bell, D. D., 1967. Poultry scratch. Univ. California Agric. Circ. 425C. 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. Nesbeth, W. G., C. R. Douglas, and R. H. Harms, 1976. The potential use of dietary salt deficiency for the force resisting of laying hens. Poultry Sci. 55:2375-2379. Safi, L. M., and B. F. Miller, 1969. Inducing and controlling reproductive pauses in laying hens. Poultry Sci. 48:1865. (Abstr.) Steel, R.G.D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill, New York. Swanson, M. H., and D. D. Bell, 1974. Force molting of chickens. II. Methods. Univ. California Agric. Ext. Leaflet 2650. Wilson, H. R., J. S. Moore, A. W. O'Steen, J. L. Fry, and R. H. Harms, 1969. Forced molting of laying hens. Florida Agric. Exp. Sta. Bull. 728.
Downloaded from http://ps.oxfordjournals.org/ at California Institute of Technology on June 19, 2015
sured at 10 weeks after feed deprivation, was significantly higher for T r e a t m e n t s 0 and 6 t h a n for 2 and 4. A l t h o u g h these differences are statistically significant, their biological importance is minimal. T h e length of time necessary for recovery in laying hens t e m p o r a r i l y deprived of feed m a y be estimated b y various measures of egg prod u c t i o n , each leading to a s o m e w h a t different conclusion. T h e interval for r e s u m p t i o n of n o r m a l rate of lay is 4 t o 8 weeks in hens deprived of feed long enough t o cause cessation of lay. Recovery t o t h e e x t e n t of restoring, in a statistical sense, t h e n o r m a l a c c u m u l a t e d n u m b e r of eggs requires 5 to 13 weeks, d e p e n d ing on t h e length of t i m e w i t h o u t feed, and 1 0 t o 17 weeks in t e r m s of absolute n u m b e r s of eggs.