- Email: [email protected]
Effect of Lighting Program and Nutrition on Reproductive Performance of Molted Single Comb White Leghorn Hens1,2
ENVIRONMENT AND HEALTH Effect of Lighting Program and Nutrition on Reproductive Performance of Molted Single Comb White Leghorn Hens 1 ' 2 D. K. ANDREWS Department of Animal Sciences, Washington State University, Western Washington Research and Extension Center, Puyallup, Washington 98371-4998 W. D. BERRY and J. BRAKE Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication September 26, 1986) ABSTRACT Two adjoining rooms in a light-tight, fan-ventilated, insulated house were used for a study involving 320 Single Comb White Leghorn hens, 60 wk of age, placed two per cage. These hens were subjected to an induced molt which compared two lighting programs, two molt rations, two levels of total sulfur amino acids (TSAA), and two levels of ascorbic acid (AA) in a factorial arrangement. There were four treatments. Treatment 1 compared the Washington lighting program (WSU), consisting of an 8-h light photoperiod for 28 days beginning 7 days before fast with the North Carolina program (NCSU), consisting of a 24-h light photoperiod for 7 days prior to fast followed by 12 h light/day for 21 days. After 28 days, light duration was increased to 16 h/day in stages for both programs. Treatment 2 consisted of feeding cracked corn (CC) or 16% protein molt ration (MR) for 2 weeks; Treatment 3, feeding of 14% layer mash with either .60% or .65% TSAA; and Treatment 4, addition of either 0 or 50 ppm AA to the 14% layer mash. After molting, egg production was increased in the NCSU lighting program and .65% TSAA treatments. Feed conversion was improved by the NCSU lighting treatment. Deaths were fewer in diets with 50 ppm AA. Egg weight, specific gravity, and shell weight were not affected by any treatment. A significant light x molt diet interaction occurred due to better performance of MR birds compared with CC birds in the NCSU lighting program, whereas on the WSU lighting program, CC produced better performance. These data indicated that combining features of various molt programs may not produce optimum results. (Key words: induced molt, lighting program, molt diet, total sulfur amino acids, layer diet, ascorbic acid) 1987 Poultry Science 66:1298-1305 INTRODUCTION
Molting White Leghorn hens for a second laying cycle has been historically used as an economic alternative by Washington and Oregon poultrymen for over 50 years (Knowlton, 1936; Frasier, 1948). Early methods were adapted to small flocks of floor birds: water and feed were removed for short periods and feed was limited for various lengths of time with
'Washington State University Scientific Paper Number 7455 and Research Project Number 0643, Washington State University, College of Agriculture and Home Economics, Western Washington Research and Extension Center, Puyallup, WA 98371-4998. Paper Number 10698 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. 2 A portion of these data were presented at the 74th Annual Meeting of the Poultry Science Association, Inc., July 30, 1985, Ames, IA. Research was conducted while the senior author was on sabbatical leave at North Carolina State University. The use of trade names in this paper does not constitute endorsement of products mentioned nor criticism of simlar products not mentioned.
varying results. Hansen (1966) incorporated light restriction during the molt. As poultry housing and management have improved, molting methodology has become more refined. Fasting continues to be an essential component of most induced molting programs. Mrosovsky and Sherry (1980) reported that birds undergoing natural molt often reject feed for prolonged periods. They further postulate that weight loss is a natural physiological phenomenon having survival value. This is in keeping with reports of Zeelen (1975), Lee (1982), and Zimmermann et al. (1985) indicating improved livability is associated with induced molting. It is suggested that molting has a role in health maintenance. The desired body weight reduction through continuous fasting appears to be approximately 30%. This figure is based upon observations by Swanson and Bell (1974) who determined that body weight losses during fast were directly related to the time birds were without feed. They noted that egg production rates were higher with
1298
LIGHT, NUTRITION, AND MOLT PERFORMANCE
each additional four days of feed removal. Carter and Ward (1981) reported better postmolt production from birds deprived of feed until body weight loss of 30% was achieved than from birds limited-fed to a similar weight. They also concluded that to reduce body weight loss beyond 30% prolonged the period of recuperation to where overall egg production financial returns were reduced. Baker et al. (1981, 1983) observed a positive correlation between postmolt performance and increasing body weight loss of hens shedding up to 31 % of their original premolt body weight. This improvement was associated with improved egg shell quality and numbers of eggs laid. Baker etal. (1983) stated that weight reductions of approximately 27 to 31% produced optimum postmolt performance. Prior to this, Brake and Thaxton (1979) found that 25% of total body weight loss was directly attributable to regression of the liver, ovary, and oviduct. They further stated that both regression and subsequent redevelopment of these organs were related to improved postmolt performance. A molt diet is a postfast, prelay diet used following the period of fasting until egg production recommences, at which time a layer ration is again provided. Simple low-protein molt diets have been favored by the west coast poultry industry as an inexpensive, effective method of controlling weight loss. Brake etal. (1979) were among the first to compare a fortified ground corn ration with a balanced pullet grower ration during the molt phase.They reported an improvement in production of 5 eggs per hen for the pullet grower molt ration. Harms (1983) compared molting diets of 8.6 and 16.2% protein. Results indicated hens on the higher protein diet laid significantly more eggs during the early portion of the laying period. Hens on the lower protein diet ate less feed and laid significantly smaller eggs. Hansen (1960, 1961) reported that compared with natural day length (16 h or more in June and July), restriction of light to 8 h/day for 2 wk before starting the molting procedure and during the molting and resting period resulted in a more complete molt, earlier cessation of egg production, virtually no egg production during the resting period, and increased egg production following the return to lay. Hansen (1966, 1969) further declared that continuing light reduction kept hens out of production, although they were returned to feed. Brake and Thaxton (1982) also demonstrated that decreased photoperiods during the molting period hasten the
1299
induction of molting and reduce mortality during the molt. However, Brake and Carey (1983) suggested increasing the daylength to 24 h light for one week prior to initiation of fasting, followed by a reduction to only 12 h light during the fast. This was intended to sensitize the photoreceptors to accept less stringent photoperiod reduction as nonstimulatory and allow a longer eating period for nutrient assimilation during postfast feeding. Ascorbic acid (AA) has been reported to improve shell thickness in 13% protein diets (Thornton, 1960). In cockerels, AA improved livability during heat stress (Pardue and Thaxton, 1982). The objective of this study was to compare the effects of lighting program, molt diet, postmolt layer total sulfur amino acids (TSAA), and postmolt layer AA on subsequent egg production. A factorial arrangement of treatments was used. MATERIALS AND METHODS
Three hundred-twenty Dekalb XL, Single Comb Leghorn hens, 60 wk of age, plus extras, were obtained from a commercial source. These birds, at 80% production, were placed two per cage, five cages per replicate in an insulated, fan-ventilated, light-tight building. The building was divided in half with a light-proof partition which allowed air movement between the two sections. Both sections shared a common air inlet and the fan ventilation was managed so that the environment of the two sections was the same. The experiment began May 29 and terminated February 4. The basic experimental design was a 2 x 2 x 2 x 2 factorial with treatments of lighting program, molt diet, TSAA, and AA. The sequence of lighting program and different diets is depicted schematically in Figure 1. Hens were maintained on 16 h of light and a 17% protein laying ration for 2 wk prior to the start of the experiment. This interval allowed for substitution from extra birds to more nearly equate body weight and egg production across replicates. On Day 1, daylength was increased to 24 h/day for 1 wk in the North Carolina State University (NCSU) lighting program room, and reduced to 8 h/day for 4 wk in the Washington State University (WSU) lighting program room. On Day 8 feed was removed from all birds and 24-h light was decreased to 12 h per day for 3 wk in the NCSU program. On Day 29, the 12-h light
1300
ANDREWS ET AL.
24 20
8
a
17% LAYER FAST MOLT 14% LAYER
4 6 8 10 TIME (Wk)
FIG. I. Schematic representation of time course of treatments. Dotted line is the North Carolina State University (NCSU) lighting program and solid line is the Washington State University (WSU) lighting program. During the molt period either a molt ration or cracked corn was fed. The 14% layer contained .60% or .65% total sulfur amino acids and 0 or 50 ppm ascorbic acid in a 2 X 2 arrangement.
NCSU treatment was increased to 14 h light for a 4-wk period. The 8-h light WSU treatment was increased to 10 h/day for 2 wk, then raised to 13 h light/day. At the start of the 8th wk, both NCSU and WSU lighting program treatments were increased to 15 h of light/day for a period of 4 wk, then increased to 16 light/day for the duration of the experiment. All birds had water available ad libitum throughout the experiment. The light source was provided by four ceilingmounted, 60-watt incandescent bulbs per room. Light intensity was measured by a Gossen Panlux electronic light meter (Kling Photo Company, P.O. Box 1060, Woodside, NY 11377) at nine sites at feed-trough level per room. Intensity varied from 24 to 47 lx/site. Across replicates within each room, intensity varied from 30 to 39 lx. Rooms averaged 34 lx each. Following a body weight loss of approximately 30%, which required a 14-day fast, two molt diets were fed. A limited nutrient ration of cracked corn (CC) was compared with a balanced molt ration (MR) containing 16% protein, 2.5% calcium, .64% phosphorus, and extra methionine (Table 1). Birds were on these diets for 2 wk until 5% production occurred, at which time a 14% protein, corn-soy, layer ration containing 3.5% calcium and .6% phosphorus was started. This ration was further divided into
treatments with .60% and .65% TSAA with and without 50 ppm AA. The 14% protein level was chosen to provide an adequate, but limiting. nutritional plane against which TSAA effects could be judged. Ascorbic acid, coated to insure stability (Roche Chemical Company, Nutley, NJ), was added to evaluate possible effects on stress. Individual bird weights from four identified birds in each replicate were taken on Days 1, 21, 35, 56, and every subsequent 28 days throughout the experiment. Feed consumption, egg weight of five randomly selected eggs per replicate, egg specific gravity, and egg shell weight were recorded for each period. Egg production was summarized by week as well as by period. Results were subjected to analysis of variance using the Statistical Analysis System Institute, Inc. (1982) general linear models procedure. RESULTS
Initial average body weights of treatments at time of feed withdrawal were uniform (1,686 ± 12 g) as were final body weights at 36 wk (1,674 ± 15 g). Weight reduction at end of fasting was 31 to 32% per treatment.The only significant difference observed in body weights occurred at 35 days in hens on MR and CC diets (data not shown), due to the rapid return of body weight of MR birds relative to the slow recovery of CC birds. Effects of lighting treatment, molt diet, TSAA, and A A are summarized in Table 2. Hens in the NCSU lighting program exhibited significantly (P=£.05) higher egg production (hen-day and eggs per hen housed) and feed efficiency when compared to hens in the WSU lighting program. Molt diet had no significant effect on egg production. Feeding layer ration with additional TSAA (.65%) produced a significant difference (P«£.05) in hen-day production (Table 2). This was due to an additional daily intake of 47 mg TSAA comprised of methionine as feed consumption did not differ and consequently consumption of other nutrients did not differ. The presence of AA at 50 ppm in the layer ration was effective (P=s.05) in reducing mortality. There were no significant treatment effects on any of the egg quality measurements studied. There was a significant interaction between lighting program and molt diet. This interaction, shown in Table 3, indicates that in this experiment. the combination of the NCSU lighting program and the MR diet significantly improved
2,600
.322 .273 .595 .729 .151
.61
13.9 3.52
1.7 5.0 2.7 .3 .05 .05 .05
73.2 17.0
0 ppm AA1
.60% TSAA'
-
13.9 3.52 .61 .322 .273 .595 .729 .151 2,600
1.7 5.0 2.7 .3 .05 .05 .05 .023
73.2 17.0
(%)
-
50 ppm AA
The trace mineral premix provided the following quantities per kilogram of diet: 150 mgMn; 100 mg Zn; 50 mg F
TSAA = Total sulfur amino acids; AA = ascorbic acid.
2,775
.355 .301 .656 .856 .183
2.5 .64
15.8
2.0 .3 .06 .05 .05
3.15
1.7
63.7 18.5 10.5
Molt
4
Layer ration was analyzed and found to contain 13.9% crude protein.
3 The vitamin premix provided the following quantities per kilogram of diet: 13,200 IV vitamin A; 6,600 IU vi 17.6 mg riboflavin; 66 mg niacin; 22 mg d-pantothenic acid; 2.2 mg pyridoxine; 2.2 mg thiamine; 22 Mg d-biotin; 4 mg
2
1
Ground corn Soybean meal (48%) Alfalfa Defluorinated phosphate Limestone Pullet oyster shell NaCl DL-Methionine Minerals2 Vitamins3 Ascorbic acid Calculated analysis Protein 4 Calcium Phosphorus (total) Methionine Cystine TSAA Lysine Tryptophan Metabolizable energy, kcal/kg
Ingredients
TABLE 1. Composition of experimental diets (% of diet)
63.9* 156.7* 1.6b 6.9* 62.67* 1.0816* 5.57*
Hen-day production, % Eggs/hen housed, no. Feed/dozen, kg Mortality, % Egg weight, g Specific gravity Shell weight, g
MR 61.8* 152.5* 1.7* 5.6* 63.04* 1.081?!* 5.64*
WSU
58.9 b 145.7 b 1.8* 3.1* 62.73* 1.0827* 5.66* 61.0* 149.9* 1.6* 4.4* 62.36* 1.0825* 5.60*
CC
Molt diet 2
60.2* 148.4* 1.7* 5.0* 62.49* 1.0824* 5.61*
.60%
Layer
4
3
2
AA = Ascorbic acid in layer rations.
TSAA = Total sulfur amino acids in layer rations (.60% and .65% levels of added methionine and cystine).
MR = Fortified molt mash 2 wk postfast;CC = cracked corn 2 wk postfast.
1 NCSU = North Carolina State University increased lighting premolt to 24 h/day for 1 wk, then 12 h for 3 wk, 14 der of treatment. WSU = Washington State University decreased lighting premolt to 8 h/day for 1 wk, continued at 8 h for 2 wk, 15 h for 4 wk, and 16 h/day for remainder of treatment.
*' Means for treatments within main effects with different superscripts differ significantly (P<.05).
NCSU
Variable
Lighting program 1
TABLE 2. Effect of lighting program, molt diet, postmolt layer ration, total sulfur amino on cumulative egg production, feed efficiency, and mortality
LIGHT, NUTRITION, AND MOLT PERFORMANCE
1303
TABLE 3. The effect of lighting program and molt diet on egg production, feed efficiency, and mortality Light:ing program 2 Variable
Molt diet1
Hen-day production, %3
MR CC X
66.3 61.6 63.9 a
57.3 60.4 58.8 b
61.8 a 61.0 a
Egg per hen housed 3
MR CC X
162.3 151.1 156.7 a
142.7 148.8 145.7 b
152.5 a 149.9 a
Feed per dozen eggs, kg
MR CC X
1.55 1.60 1.58 b
1.82 1.67 1.75 a
1.68a 1.64a
Mortality, 5
MR CC X
8.8 5.0 6.9 a
2.5 3.8 3.1 a
5.6 a 4.4 a
NCSU
WSU
X
a ' b Means for main effects which possess different superscripts differ significantly (P<.05). 1
MR = Molt ration; CC = cracked corn.
2
NCSU = North Carolina State University; WSU = Washington State University; see Figure 1 for details of lighting programs. 3
Significant lighting program X molt diet interaction (P<.05).
(Pss.05) egg production over the combination of the WSU lighting program and the CC diet. Birds on the NCSU lighting program and MR diet laid 66.3 vs. 61.6% or 11 eggs more per hen than similarly lighted hens fed CC. Conversely, the WSU lighting program caused hens to lay at a higher rate on the CC diet than they did with MR, 60.4 vs. 57.3%, an improvement
of 6 eggs/hen. Table 4 shows the early egg per hen housed production of the NCSU and WSU lighting programs combined with the MR and CC diets. The WSU lighting program and CC yielded essentially zero eggs through the 8th wk, whereas the NCSU lighting program plus MR gave 8 eggs/hen. Production losses occurring at this time were never recaptured.
TABLE 4. Interaction of lighting program1 and molt diet2 during onset of production postmolt on eggs per hen housed NCSU Weeks
CC
WSU MR
CC
MR
(no.) 5 6 7 8 9 10 5 to 8 5 to 10
.00 .04 1.25 2.95 3.67 4.69
.01 1.91 2.80 3.39 4.06 5.10
.00 .00 .05 .07 2.40 3.77
.04 .70 .49 1.01 2.11 4.07
4.24 12.60
8.11 17.26
.12 6.92
2.22 8.39
'NCSU = North Carolina State University; WSU = Washington State University; see Figure 1 for details of lighting programs. 2
MR = Molt ration; CC = cracked corn.
ANDREWS ET AL.
1304 DISCUSSION
Brake and Carey (1983) previously suggested that increasing daylength to 24 h for 1 wk prior to inducing molt further stimulated, or sensitized, the photoreceptor system of the chicken to accept less stringent hours of light reduction during the molt in open housing. This, plus the 12-h resting period daylength through the 21 days after the initiation of fasting, was intended to accomplish the twofold purpose of gaining a few eggs prior to fasting, as well as a longer eating period for nutrient assimilation during postfast feeding. In this experiment, where both the NCSU and WSU premolt lighting programs were applied for only 1 wk, results of premolt egg production were nearly identical (7.62 to 7.45 eggs/hen housed). The effect of the NCSU lighting program manifested itself 6 to 10 wk later with an increase of 7.2 more eggs/hen housed. This higher production rate continued throughout the 36-wk trial. Egg production, on a hen-day basis, was improved by the .65 TSAA treatment. This was due to an earlier peak and sustained production. This can be attributed to availability of appropriate precursors (TSAA) in adequate quantities to allow for completion of feather growth and initiation of egg production simultaneously. Reduced mortality, due to the addition of 50 ppm AA to the laying diet, was consistent with previous reports that AA could function as an antistress agent (Pardue and Thaxton, 1982) during hot weather. The nonsignificant increase observed in eggs per hen housed was consistent with the results of Thornton (1960) wherein production was increased on a low protein layer ration by the addition of AA. In this experiment, the beneficial effects of AA were observed from the 7th through 16th wk, that is, through the months of July, August, and September, when ambient temperatures ranged between 21 and 35 C. Although there were no significant effects due to molt diet, there were significant interactions of lighting program with molt diet for both hen-day and hen housed egg production. This interaction is shown in Table 4, which demonstrates effectively the value of the NCSU lighting program and MR diet on reproductive rejuvenation manifested in enhanced onset of production during the 5th through 10th weeks. Not until the 11th week was egg production equalled by the WSU lighting program or CC treatments. Part of this delay was predictable because the WSU lighting program did not reach a stimula-
tory duration of 13 h/day until Day 42, whereas the NCSU treatment was never below 12 h light/ day. By the end of the 10th week the extremes were 17.3 eggs for the NCSU-MR combination vs. 6.9 eggs for the WSU-CC combination. A comparison by diet of final egg numbers shows them to be MR, 152.5; and CC, 149.9 eggs. Separation of data reveals that the NCSU-CC diet combination, while only 5 eggs below the NCSU-MR combination at 10 wk, finished 11 eggs lower at 36 wk (151.1 vs. 162.3 eggs). A review of the ninth period egg records indicates that the lower producing treatments were not improving. Only the NCSU-MR combination sustained 70% weekly production throughout the final period. A possible explanation of why the WSU-MR combination did so poorly in egg production may be related to three factors: 1) a significant increase in body weight on the 35th day. They had the only statistically aberrant weight increase noted. 2) Their WSU-MR egg production increase started in the 5th wk, increased in the 6th, faltered in the 7th and 9th wk, whereas all other treatments were consistently increasing. 3) The WSU-MR hens were struggling to produce for 4 wk, whereas the WSU-CC group was dormant until the 9th wk, when it increased abruptly to 34% production. Evidence that the abrupt weight increase without light stimulation is detrimental is provided by their later consistently poorest weekly showing in egg production. Beginning in the 11th wk, WSU-MR hens were lowest in 23 of the remaining 25 wk. Their peak of 80% for 1 wk compares to NCSU-MR and WSU-CC combinations sustaining 80% or better for 13 wk and NCSU-CC combination for 4 wk. They did not suffer higher than average mortality. The poor results of this aspect of this trial may explain problems experienced by the poultry industry when they have implemented improvisations on existing recommended molting procedures. The poorer egg production from the NCSU-CC combination also implies that added light without increased nutrition is not adequate for maximum results. A comparison of egg weights taken during the first week of the experiment (initiation of lighting programs) reveals little difference between those and egg weights taken at 4-wk intervals thereafter. Specific gravity and shell weight exhibited the normal improvement and gradual decline as expected of molted flocks (Swanson and Bell, 1971). There were no differences between treatments.
LIGHT, NUTRITION, AND MOLT PERFORMANCE
This study used hens which laid at a rate as high as 80%, on hen-day basis, both before and after the induced molt. A similar result was also reported by Roland and Brake (1982) for their highest producing hens, with average and low producing hens performing similarly, both before and after an induced molt. This suggests that the data of this study should be broadly applicable to commercial situations. ACKNOWLEDGMENTS
The authors thank Grace Brockman, Susan Creech, and Robert Hunter for excellent technical assistance. REFERENCES Baker, ML, J. Brake, and G. R. McDaniel, 1981. Total body lipid and uterine lipid changes during a forced molt of caged layers. Poultry Sci. 60:1593. (Abstr.) Baker, M., J. Brake, and G. R. McDaniel, 1983. The relationship between body weight loss during an induced molt and postmolt egg production, egg weight, and shell quality in caged layers. Poultry Sci. 62:409-413. Brake, J. T., and J. B. Carey, 1983. Induced molting of commercial layers. North Carolina Agricultural Extension Service Poultry Science and Technical Guide No. 10. NC Agric. Ext. Serv., Raleigh, NC. Brake, J., and P. Thaxton, 1979. Physiological changes in caged layers during a forced molt. 2. Gross changes in organs. Poultry Sci. 58:707-716. Brake, J., and P. Thaxton, 1982. Comparative effect of photoperiod modification and/or fasting with a short period without water on physiological and performance parameters associated with molt in SCWL hens. Poultry Sci. 61:1423. (Abstr.) Brake, J., P. Thaxton, J. D. Garlich, and D. H. Sherwood, 1979. Comparison of fortified ground corn and pullet grower feeding regimes during a forced molt on subsequent layer performance. Poultry Sci. 58:785-790. Carter, T. A., and J. B. Ward, 1981. Limited and full feeding of layers during the non-laying period of a molting cycle. Poultry Sci. 60:1635. (Abstr.) Frasier, F., 1948. How force molting works. Poult. Tribune 54; No. 5:10. Hansen, R. S., 1960. The force molting of laying chickens.
1305
Pages 72-83 in: Washington State University Poultry Council Proceedings. July, 1960. Project No. 1303. Wash. State Univ., Puyallup, WA. Hansen, R. S., 1961. The force molting of laying chickens. Pages 67-70 in: Washington State University Poultry Council Proceedings. June 1961. Project No. 1303. Wash. State Univ., Puyallup, WA. Hansen, R. S., 1966. Reducing light to facilitate the induced rest (forced molt). Poultry Sci. 45:1089. (Abstr.) Hansen, R. S., 1969. The biology: how, what, when and why of recycling. Proc. Ohio Market Egg Day Program. Ohio State Univ., Columbus, OH. Harms, R. H., 1983. Influence of protein level in the resting diet upon performance of force-rested hens. Poultry Sci. 62:273-276. Knowlton, F. L., 1936. Force molting of white leghorn hens. Circ. No. 119. Oregon State College, Corvallis, OR. Lee, K., 1982. Effects of forced molt period on postmolt performance of Leghorn hens. Poultry Sci. 61:1594— 1598. Mrosovsky, N., and D. F. Sherry, 1980. Animal anorexias. Science 207:837-842. Pardue, S. L., and J. P. Thaxton, 1982. Enhanced livability and improved immunological responsiveness in ascorbic acid-supplemented cockerels during acute heat stress. Poultry Sci. 61:1522. (Abstr.) Roland, D. A.,Sr., and J. Brake, 1982. Influence of premolt production on postmolt performance with explanation for improvement in egg production due to force molting. Poultry Sci. 61:2473-2481. Statistical Analysis System Institute, Inc., 1982. SAS User's Guide: Statistics. 1982 ed. SAS Institute, Inc., Cary, NC. Swanson, M. H.,andD. D. Bell, 1971. Field tests of forced molting practices and performance in commercial egg production flocks. Proc. 14th World's Poultry Sci. Cong. 3:87-97. Swanson, M. H., and D. D. Bell, 1974. Force Molting of Chickens. II. Methods. University of California Leaflet 2650. Univ. of Calif., Davis, CA. Thornton, P. A., 1960. The influence of dietary protein level on the response of S.C. White Leghorns to supplementary ascorbic acid. Poultry Sci. 39:1072-1076. Zeelen, H.H.M., 1975. Technical and economic results from forced molting of laying hens. World's Poult. Sci. J. 31:57-67. Zimmermann, N. G., D. K. Andrews, and J. McGinnis, 1985. Comparison of twelve induced-molt procedures. Poultry Sci. 64(Suppl. 1):204. (Abstr.)
Molting White Leghorn hens for a second laying cycle has been historically used as an economic alternative by Washington and Oregon poultrymen for over 50 years (Knowlton, 1936; Frasier, 1948). Early methods were adapted to small flocks of floor birds: water and feed were removed for short periods and feed was limited for various lengths of time with
'Washington State University Scientific Paper Number 7455 and Research Project Number 0643, Washington State University, College of Agriculture and Home Economics, Western Washington Research and Extension Center, Puyallup, WA 98371-4998. Paper Number 10698 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. 2 A portion of these data were presented at the 74th Annual Meeting of the Poultry Science Association, Inc., July 30, 1985, Ames, IA. Research was conducted while the senior author was on sabbatical leave at North Carolina State University. The use of trade names in this paper does not constitute endorsement of products mentioned nor criticism of simlar products not mentioned.
varying results. Hansen (1966) incorporated light restriction during the molt. As poultry housing and management have improved, molting methodology has become more refined. Fasting continues to be an essential component of most induced molting programs. Mrosovsky and Sherry (1980) reported that birds undergoing natural molt often reject feed for prolonged periods. They further postulate that weight loss is a natural physiological phenomenon having survival value. This is in keeping with reports of Zeelen (1975), Lee (1982), and Zimmermann et al. (1985) indicating improved livability is associated with induced molting. It is suggested that molting has a role in health maintenance. The desired body weight reduction through continuous fasting appears to be approximately 30%. This figure is based upon observations by Swanson and Bell (1974) who determined that body weight losses during fast were directly related to the time birds were without feed. They noted that egg production rates were higher with
1298
LIGHT, NUTRITION, AND MOLT PERFORMANCE
each additional four days of feed removal. Carter and Ward (1981) reported better postmolt production from birds deprived of feed until body weight loss of 30% was achieved than from birds limited-fed to a similar weight. They also concluded that to reduce body weight loss beyond 30% prolonged the period of recuperation to where overall egg production financial returns were reduced. Baker et al. (1981, 1983) observed a positive correlation between postmolt performance and increasing body weight loss of hens shedding up to 31 % of their original premolt body weight. This improvement was associated with improved egg shell quality and numbers of eggs laid. Baker etal. (1983) stated that weight reductions of approximately 27 to 31% produced optimum postmolt performance. Prior to this, Brake and Thaxton (1979) found that 25% of total body weight loss was directly attributable to regression of the liver, ovary, and oviduct. They further stated that both regression and subsequent redevelopment of these organs were related to improved postmolt performance. A molt diet is a postfast, prelay diet used following the period of fasting until egg production recommences, at which time a layer ration is again provided. Simple low-protein molt diets have been favored by the west coast poultry industry as an inexpensive, effective method of controlling weight loss. Brake etal. (1979) were among the first to compare a fortified ground corn ration with a balanced pullet grower ration during the molt phase.They reported an improvement in production of 5 eggs per hen for the pullet grower molt ration. Harms (1983) compared molting diets of 8.6 and 16.2% protein. Results indicated hens on the higher protein diet laid significantly more eggs during the early portion of the laying period. Hens on the lower protein diet ate less feed and laid significantly smaller eggs. Hansen (1960, 1961) reported that compared with natural day length (16 h or more in June and July), restriction of light to 8 h/day for 2 wk before starting the molting procedure and during the molting and resting period resulted in a more complete molt, earlier cessation of egg production, virtually no egg production during the resting period, and increased egg production following the return to lay. Hansen (1966, 1969) further declared that continuing light reduction kept hens out of production, although they were returned to feed. Brake and Thaxton (1982) also demonstrated that decreased photoperiods during the molting period hasten the
1299
induction of molting and reduce mortality during the molt. However, Brake and Carey (1983) suggested increasing the daylength to 24 h light for one week prior to initiation of fasting, followed by a reduction to only 12 h light during the fast. This was intended to sensitize the photoreceptors to accept less stringent photoperiod reduction as nonstimulatory and allow a longer eating period for nutrient assimilation during postfast feeding. Ascorbic acid (AA) has been reported to improve shell thickness in 13% protein diets (Thornton, 1960). In cockerels, AA improved livability during heat stress (Pardue and Thaxton, 1982). The objective of this study was to compare the effects of lighting program, molt diet, postmolt layer total sulfur amino acids (TSAA), and postmolt layer AA on subsequent egg production. A factorial arrangement of treatments was used. MATERIALS AND METHODS
Three hundred-twenty Dekalb XL, Single Comb Leghorn hens, 60 wk of age, plus extras, were obtained from a commercial source. These birds, at 80% production, were placed two per cage, five cages per replicate in an insulated, fan-ventilated, light-tight building. The building was divided in half with a light-proof partition which allowed air movement between the two sections. Both sections shared a common air inlet and the fan ventilation was managed so that the environment of the two sections was the same. The experiment began May 29 and terminated February 4. The basic experimental design was a 2 x 2 x 2 x 2 factorial with treatments of lighting program, molt diet, TSAA, and AA. The sequence of lighting program and different diets is depicted schematically in Figure 1. Hens were maintained on 16 h of light and a 17% protein laying ration for 2 wk prior to the start of the experiment. This interval allowed for substitution from extra birds to more nearly equate body weight and egg production across replicates. On Day 1, daylength was increased to 24 h/day for 1 wk in the North Carolina State University (NCSU) lighting program room, and reduced to 8 h/day for 4 wk in the Washington State University (WSU) lighting program room. On Day 8 feed was removed from all birds and 24-h light was decreased to 12 h per day for 3 wk in the NCSU program. On Day 29, the 12-h light
1300
ANDREWS ET AL.
24 20
8
a
17% LAYER FAST MOLT 14% LAYER
4 6 8 10 TIME (Wk)
FIG. I. Schematic representation of time course of treatments. Dotted line is the North Carolina State University (NCSU) lighting program and solid line is the Washington State University (WSU) lighting program. During the molt period either a molt ration or cracked corn was fed. The 14% layer contained .60% or .65% total sulfur amino acids and 0 or 50 ppm ascorbic acid in a 2 X 2 arrangement.
NCSU treatment was increased to 14 h light for a 4-wk period. The 8-h light WSU treatment was increased to 10 h/day for 2 wk, then raised to 13 h light/day. At the start of the 8th wk, both NCSU and WSU lighting program treatments were increased to 15 h of light/day for a period of 4 wk, then increased to 16 light/day for the duration of the experiment. All birds had water available ad libitum throughout the experiment. The light source was provided by four ceilingmounted, 60-watt incandescent bulbs per room. Light intensity was measured by a Gossen Panlux electronic light meter (Kling Photo Company, P.O. Box 1060, Woodside, NY 11377) at nine sites at feed-trough level per room. Intensity varied from 24 to 47 lx/site. Across replicates within each room, intensity varied from 30 to 39 lx. Rooms averaged 34 lx each. Following a body weight loss of approximately 30%, which required a 14-day fast, two molt diets were fed. A limited nutrient ration of cracked corn (CC) was compared with a balanced molt ration (MR) containing 16% protein, 2.5% calcium, .64% phosphorus, and extra methionine (Table 1). Birds were on these diets for 2 wk until 5% production occurred, at which time a 14% protein, corn-soy, layer ration containing 3.5% calcium and .6% phosphorus was started. This ration was further divided into
treatments with .60% and .65% TSAA with and without 50 ppm AA. The 14% protein level was chosen to provide an adequate, but limiting. nutritional plane against which TSAA effects could be judged. Ascorbic acid, coated to insure stability (Roche Chemical Company, Nutley, NJ), was added to evaluate possible effects on stress. Individual bird weights from four identified birds in each replicate were taken on Days 1, 21, 35, 56, and every subsequent 28 days throughout the experiment. Feed consumption, egg weight of five randomly selected eggs per replicate, egg specific gravity, and egg shell weight were recorded for each period. Egg production was summarized by week as well as by period. Results were subjected to analysis of variance using the Statistical Analysis System Institute, Inc. (1982) general linear models procedure. RESULTS
Initial average body weights of treatments at time of feed withdrawal were uniform (1,686 ± 12 g) as were final body weights at 36 wk (1,674 ± 15 g). Weight reduction at end of fasting was 31 to 32% per treatment.The only significant difference observed in body weights occurred at 35 days in hens on MR and CC diets (data not shown), due to the rapid return of body weight of MR birds relative to the slow recovery of CC birds. Effects of lighting treatment, molt diet, TSAA, and A A are summarized in Table 2. Hens in the NCSU lighting program exhibited significantly (P=£.05) higher egg production (hen-day and eggs per hen housed) and feed efficiency when compared to hens in the WSU lighting program. Molt diet had no significant effect on egg production. Feeding layer ration with additional TSAA (.65%) produced a significant difference (P«£.05) in hen-day production (Table 2). This was due to an additional daily intake of 47 mg TSAA comprised of methionine as feed consumption did not differ and consequently consumption of other nutrients did not differ. The presence of AA at 50 ppm in the layer ration was effective (P=s.05) in reducing mortality. There were no significant treatment effects on any of the egg quality measurements studied. There was a significant interaction between lighting program and molt diet. This interaction, shown in Table 3, indicates that in this experiment. the combination of the NCSU lighting program and the MR diet significantly improved
2,600
.322 .273 .595 .729 .151
.61
13.9 3.52
1.7 5.0 2.7 .3 .05 .05 .05
73.2 17.0
0 ppm AA1
.60% TSAA'
-
13.9 3.52 .61 .322 .273 .595 .729 .151 2,600
1.7 5.0 2.7 .3 .05 .05 .05 .023
73.2 17.0
(%)
-
50 ppm AA
The trace mineral premix provided the following quantities per kilogram of diet: 150 mgMn; 100 mg Zn; 50 mg F
TSAA = Total sulfur amino acids; AA = ascorbic acid.
2,775
.355 .301 .656 .856 .183
2.5 .64
15.8
2.0 .3 .06 .05 .05
3.15
1.7
63.7 18.5 10.5
Molt
4
Layer ration was analyzed and found to contain 13.9% crude protein.
3 The vitamin premix provided the following quantities per kilogram of diet: 13,200 IV vitamin A; 6,600 IU vi 17.6 mg riboflavin; 66 mg niacin; 22 mg d-pantothenic acid; 2.2 mg pyridoxine; 2.2 mg thiamine; 22 Mg d-biotin; 4 mg
2
1
Ground corn Soybean meal (48%) Alfalfa Defluorinated phosphate Limestone Pullet oyster shell NaCl DL-Methionine Minerals2 Vitamins3 Ascorbic acid Calculated analysis Protein 4 Calcium Phosphorus (total) Methionine Cystine TSAA Lysine Tryptophan Metabolizable energy, kcal/kg
Ingredients
TABLE 1. Composition of experimental diets (% of diet)
63.9* 156.7* 1.6b 6.9* 62.67* 1.0816* 5.57*
Hen-day production, % Eggs/hen housed, no. Feed/dozen, kg Mortality, % Egg weight, g Specific gravity Shell weight, g
MR 61.8* 152.5* 1.7* 5.6* 63.04* 1.081?!* 5.64*
WSU
58.9 b 145.7 b 1.8* 3.1* 62.73* 1.0827* 5.66* 61.0* 149.9* 1.6* 4.4* 62.36* 1.0825* 5.60*
CC
Molt diet 2
60.2* 148.4* 1.7* 5.0* 62.49* 1.0824* 5.61*
.60%
Layer
4
3
2
AA = Ascorbic acid in layer rations.
TSAA = Total sulfur amino acids in layer rations (.60% and .65% levels of added methionine and cystine).
MR = Fortified molt mash 2 wk postfast;CC = cracked corn 2 wk postfast.
1 NCSU = North Carolina State University increased lighting premolt to 24 h/day for 1 wk, then 12 h for 3 wk, 14 der of treatment. WSU = Washington State University decreased lighting premolt to 8 h/day for 1 wk, continued at 8 h for 2 wk, 15 h for 4 wk, and 16 h/day for remainder of treatment.
*' Means for treatments within main effects with different superscripts differ significantly (P<.05).
NCSU
Variable
Lighting program 1
TABLE 2. Effect of lighting program, molt diet, postmolt layer ration, total sulfur amino on cumulative egg production, feed efficiency, and mortality
LIGHT, NUTRITION, AND MOLT PERFORMANCE
1303
TABLE 3. The effect of lighting program and molt diet on egg production, feed efficiency, and mortality Light:ing program 2 Variable
Molt diet1
Hen-day production, %3
MR CC X
66.3 61.6 63.9 a
57.3 60.4 58.8 b
61.8 a 61.0 a
Egg per hen housed 3
MR CC X
162.3 151.1 156.7 a
142.7 148.8 145.7 b
152.5 a 149.9 a
Feed per dozen eggs, kg
MR CC X
1.55 1.60 1.58 b
1.82 1.67 1.75 a
1.68a 1.64a
Mortality, 5
MR CC X
8.8 5.0 6.9 a
2.5 3.8 3.1 a
5.6 a 4.4 a
NCSU
WSU
X
a ' b Means for main effects which possess different superscripts differ significantly (P<.05). 1
MR = Molt ration; CC = cracked corn.
2
NCSU = North Carolina State University; WSU = Washington State University; see Figure 1 for details of lighting programs. 3
Significant lighting program X molt diet interaction (P<.05).
(Pss.05) egg production over the combination of the WSU lighting program and the CC diet. Birds on the NCSU lighting program and MR diet laid 66.3 vs. 61.6% or 11 eggs more per hen than similarly lighted hens fed CC. Conversely, the WSU lighting program caused hens to lay at a higher rate on the CC diet than they did with MR, 60.4 vs. 57.3%, an improvement
of 6 eggs/hen. Table 4 shows the early egg per hen housed production of the NCSU and WSU lighting programs combined with the MR and CC diets. The WSU lighting program and CC yielded essentially zero eggs through the 8th wk, whereas the NCSU lighting program plus MR gave 8 eggs/hen. Production losses occurring at this time were never recaptured.
TABLE 4. Interaction of lighting program1 and molt diet2 during onset of production postmolt on eggs per hen housed NCSU Weeks
CC
WSU MR
CC
MR
(no.) 5 6 7 8 9 10 5 to 8 5 to 10
.00 .04 1.25 2.95 3.67 4.69
.01 1.91 2.80 3.39 4.06 5.10
.00 .00 .05 .07 2.40 3.77
.04 .70 .49 1.01 2.11 4.07
4.24 12.60
8.11 17.26
.12 6.92
2.22 8.39
'NCSU = North Carolina State University; WSU = Washington State University; see Figure 1 for details of lighting programs. 2
MR = Molt ration; CC = cracked corn.
ANDREWS ET AL.
1304 DISCUSSION
Brake and Carey (1983) previously suggested that increasing daylength to 24 h for 1 wk prior to inducing molt further stimulated, or sensitized, the photoreceptor system of the chicken to accept less stringent hours of light reduction during the molt in open housing. This, plus the 12-h resting period daylength through the 21 days after the initiation of fasting, was intended to accomplish the twofold purpose of gaining a few eggs prior to fasting, as well as a longer eating period for nutrient assimilation during postfast feeding. In this experiment, where both the NCSU and WSU premolt lighting programs were applied for only 1 wk, results of premolt egg production were nearly identical (7.62 to 7.45 eggs/hen housed). The effect of the NCSU lighting program manifested itself 6 to 10 wk later with an increase of 7.2 more eggs/hen housed. This higher production rate continued throughout the 36-wk trial. Egg production, on a hen-day basis, was improved by the .65 TSAA treatment. This was due to an earlier peak and sustained production. This can be attributed to availability of appropriate precursors (TSAA) in adequate quantities to allow for completion of feather growth and initiation of egg production simultaneously. Reduced mortality, due to the addition of 50 ppm AA to the laying diet, was consistent with previous reports that AA could function as an antistress agent (Pardue and Thaxton, 1982) during hot weather. The nonsignificant increase observed in eggs per hen housed was consistent with the results of Thornton (1960) wherein production was increased on a low protein layer ration by the addition of AA. In this experiment, the beneficial effects of AA were observed from the 7th through 16th wk, that is, through the months of July, August, and September, when ambient temperatures ranged between 21 and 35 C. Although there were no significant effects due to molt diet, there were significant interactions of lighting program with molt diet for both hen-day and hen housed egg production. This interaction is shown in Table 4, which demonstrates effectively the value of the NCSU lighting program and MR diet on reproductive rejuvenation manifested in enhanced onset of production during the 5th through 10th weeks. Not until the 11th week was egg production equalled by the WSU lighting program or CC treatments. Part of this delay was predictable because the WSU lighting program did not reach a stimula-
tory duration of 13 h/day until Day 42, whereas the NCSU treatment was never below 12 h light/ day. By the end of the 10th week the extremes were 17.3 eggs for the NCSU-MR combination vs. 6.9 eggs for the WSU-CC combination. A comparison by diet of final egg numbers shows them to be MR, 152.5; and CC, 149.9 eggs. Separation of data reveals that the NCSU-CC diet combination, while only 5 eggs below the NCSU-MR combination at 10 wk, finished 11 eggs lower at 36 wk (151.1 vs. 162.3 eggs). A review of the ninth period egg records indicates that the lower producing treatments were not improving. Only the NCSU-MR combination sustained 70% weekly production throughout the final period. A possible explanation of why the WSU-MR combination did so poorly in egg production may be related to three factors: 1) a significant increase in body weight on the 35th day. They had the only statistically aberrant weight increase noted. 2) Their WSU-MR egg production increase started in the 5th wk, increased in the 6th, faltered in the 7th and 9th wk, whereas all other treatments were consistently increasing. 3) The WSU-MR hens were struggling to produce for 4 wk, whereas the WSU-CC group was dormant until the 9th wk, when it increased abruptly to 34% production. Evidence that the abrupt weight increase without light stimulation is detrimental is provided by their later consistently poorest weekly showing in egg production. Beginning in the 11th wk, WSU-MR hens were lowest in 23 of the remaining 25 wk. Their peak of 80% for 1 wk compares to NCSU-MR and WSU-CC combinations sustaining 80% or better for 13 wk and NCSU-CC combination for 4 wk. They did not suffer higher than average mortality. The poor results of this aspect of this trial may explain problems experienced by the poultry industry when they have implemented improvisations on existing recommended molting procedures. The poorer egg production from the NCSU-CC combination also implies that added light without increased nutrition is not adequate for maximum results. A comparison of egg weights taken during the first week of the experiment (initiation of lighting programs) reveals little difference between those and egg weights taken at 4-wk intervals thereafter. Specific gravity and shell weight exhibited the normal improvement and gradual decline as expected of molted flocks (Swanson and Bell, 1971). There were no differences between treatments.
LIGHT, NUTRITION, AND MOLT PERFORMANCE
This study used hens which laid at a rate as high as 80%, on hen-day basis, both before and after the induced molt. A similar result was also reported by Roland and Brake (1982) for their highest producing hens, with average and low producing hens performing similarly, both before and after an induced molt. This suggests that the data of this study should be broadly applicable to commercial situations. ACKNOWLEDGMENTS
The authors thank Grace Brockman, Susan Creech, and Robert Hunter for excellent technical assistance. REFERENCES Baker, ML, J. Brake, and G. R. McDaniel, 1981. Total body lipid and uterine lipid changes during a forced molt of caged layers. Poultry Sci. 60:1593. (Abstr.) Baker, M., J. Brake, and G. R. McDaniel, 1983. The relationship between body weight loss during an induced molt and postmolt egg production, egg weight, and shell quality in caged layers. Poultry Sci. 62:409-413. Brake, J. T., and J. B. Carey, 1983. Induced molting of commercial layers. North Carolina Agricultural Extension Service Poultry Science and Technical Guide No. 10. NC Agric. Ext. Serv., Raleigh, NC. Brake, J., and P. Thaxton, 1979. Physiological changes in caged layers during a forced molt. 2. Gross changes in organs. Poultry Sci. 58:707-716. Brake, J., and P. Thaxton, 1982. Comparative effect of photoperiod modification and/or fasting with a short period without water on physiological and performance parameters associated with molt in SCWL hens. Poultry Sci. 61:1423. (Abstr.) Brake, J., P. Thaxton, J. D. Garlich, and D. H. Sherwood, 1979. Comparison of fortified ground corn and pullet grower feeding regimes during a forced molt on subsequent layer performance. Poultry Sci. 58:785-790. Carter, T. A., and J. B. Ward, 1981. Limited and full feeding of layers during the non-laying period of a molting cycle. Poultry Sci. 60:1635. (Abstr.) Frasier, F., 1948. How force molting works. Poult. Tribune 54; No. 5:10. Hansen, R. S., 1960. The force molting of laying chickens.
1305
Pages 72-83 in: Washington State University Poultry Council Proceedings. July, 1960. Project No. 1303. Wash. State Univ., Puyallup, WA. Hansen, R. S., 1961. The force molting of laying chickens. Pages 67-70 in: Washington State University Poultry Council Proceedings. June 1961. Project No. 1303. Wash. State Univ., Puyallup, WA. Hansen, R. S., 1966. Reducing light to facilitate the induced rest (forced molt). Poultry Sci. 45:1089. (Abstr.) Hansen, R. S., 1969. The biology: how, what, when and why of recycling. Proc. Ohio Market Egg Day Program. Ohio State Univ., Columbus, OH. Harms, R. H., 1983. Influence of protein level in the resting diet upon performance of force-rested hens. Poultry Sci. 62:273-276. Knowlton, F. L., 1936. Force molting of white leghorn hens. Circ. No. 119. Oregon State College, Corvallis, OR. Lee, K., 1982. Effects of forced molt period on postmolt performance of Leghorn hens. Poultry Sci. 61:1594— 1598. Mrosovsky, N., and D. F. Sherry, 1980. Animal anorexias. Science 207:837-842. Pardue, S. L., and J. P. Thaxton, 1982. Enhanced livability and improved immunological responsiveness in ascorbic acid-supplemented cockerels during acute heat stress. Poultry Sci. 61:1522. (Abstr.) Roland, D. A.,Sr., and J. Brake, 1982. Influence of premolt production on postmolt performance with explanation for improvement in egg production due to force molting. Poultry Sci. 61:2473-2481. Statistical Analysis System Institute, Inc., 1982. SAS User's Guide: Statistics. 1982 ed. SAS Institute, Inc., Cary, NC. Swanson, M. H.,andD. D. Bell, 1971. Field tests of forced molting practices and performance in commercial egg production flocks. Proc. 14th World's Poultry Sci. Cong. 3:87-97. Swanson, M. H., and D. D. Bell, 1974. Force Molting of Chickens. II. Methods. University of California Leaflet 2650. Univ. of Calif., Davis, CA. Thornton, P. A., 1960. The influence of dietary protein level on the response of S.C. White Leghorns to supplementary ascorbic acid. Poultry Sci. 39:1072-1076. Zeelen, H.H.M., 1975. Technical and economic results from forced molting of laying hens. World's Poult. Sci. J. 31:57-67. Zimmermann, N. G., D. K. Andrews, and J. McGinnis, 1985. Comparison of twelve induced-molt procedures. Poultry Sci. 64(Suppl. 1):204. (Abstr.)