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The Effect on Postmolt Performance of Different Crude Protein and Energy Levels During a Full-Fed Molt Procedure

Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg 24061

Correspondence: ¹ Corresponding author: plrus{at}vt.edu

	SUMMARY

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 
There is a need to evaluate the different dietary levels of CP and ME needed by the hen and the time sequence during the molt period to feed these levels to simulate a molt similar to that of nature by utilizing full feeding molting procedures. This study was undertaken to determine that nutritional sequence information. The 4-d feed withdrawal molt procedure being used commercially was used to compare the effects of the 3 procedures studied. Very low levels of CP and ME (9.72% CP and 1,103 kcal or 9.72% CP and 1,433 kcal) were fed for 2, 3, and 4 wk to mimic the levels of nutrients consumed by hens during the first 4 wk of the 4-d molt procedure. The equivalent of zero egg production (0.3%) was achieved during wk 2, 3, and 4 of the study (postmolt initiation). The hens achieved 50% production during wk 7 postmolt and peak production, 6 to 8 points below the first cycle, occurred during wk 11 of the study. Body weight reduction ranged from 20 to 29%. The lowest energy level fed for 4 wk was not a desirable molting procedure. Full-fed molting procedures resulted in a significant but acceptable increase in cost of feed over the 4-d procedure.

Key Words: induced molt • energy and protein • low nutrient • egg production

	DESCRIPTION OF PROBLEM

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 
Past molting procedures have utilized some period of feed withdrawal to be effective. This was done to induce a complete cessation of lay to create some period of rest and time for tissue rejuvenation. The flock performance in the resulting postmolt laying cycle was usually determined by the length of the rest period as well as the various levels of nutrition supplied by the molting process used.

There has been concern expressed in recent years about the physical welfare of the hen during a molt. Even though a bird going through a natural molt will reject feed for an extended period as reported by Mrosovsky and Sherry [1], there is concern centering upon whether it is harmful to initiate a molt before the bird is physiologically ready. Studies have been carried out to determine effective, yet simple, methods of molting hens that do not require feed deprivation. The current American Veterinary Medical Association’s Policy Statement and Guidelines [2] on induced molting states, in part: "Acceptable (molting) practices include reduction of photoperiod ‘day length’ and dietary restrictions that result in cessation of egg production, but water should not be withdrawn. Intermittent feeding of diets of low nutrient density is recommended rather than total feed withdrawal. The AMVA encourages ongoing research into the effect of various methods of induced molting on the performance and well-being of laying chickens."

The United Egg Producers (UEP) original position statement for induced molting in 2002 [3] stated that "Producers and researchers are encouraged to work together to develop alternatives to feed withdrawal for molting." After the development of nonfeed withdrawal molting, 2 of the 2006 UEP guidelines that became effective January 1, 2006 [4], state that "1) Only non-feed withdrawal molt methods will be permitted after January 1, 2006, and 2) The hens should be able to consume nutritionally adequate and palatable feed suitable for a non-producing hen." Limited availability of food is one of the factors triggering seasonal fasting of wild avian species, resulting in a temporary condition of anorexia according to Anderson and Jones [5]. The same phenomenon occurs when molting with periods of complete feed withdrawal.

Ruszler and Minear [6] showed in 1997 that a low-energy-high-fiber molt diet full fed to hens after a 4-d feed withdrawal induced a molt that was as equally effective as other commercial molts using longer periods of feed withdrawal. Following that, Minear [7] fed low-energy-high-fiber diets to commercial flocks with no period of feed withdrawal and found that it would induce a molt. However, this method did not accomplish a complete cessation of lay resulting in less-than-optimal postmolt performance. Results similar to Minear were reported by Biggs and others in 2003 [8] and again in 2004 [9], which also showed that not all treatments achieved zero production. These trials were partial answers to the alternatives requested by UEP in 2002. Further studies by Ruszler et al. in 2004 [10] and followed up by Ruszler and Novak in 2005 [11] showed that hens full fed a molt diet of 9.5% CP and 1,430 kcal/kg with no period of feed withdrawal did achieve zero egg production from 1 to 2 wk. The earlier studies had used higher levels of CP and ME, which may have been the reason they were not as successful. Donaldson et al. [12] successfully molted hens and also achieved zero production by full feeding various amounts of alfalfa.

Ruszler and Novak [13] recently reported feeding 2 diets with 9.7% CP and either 1,100 or 1,430 kcal of ME plus a third standard molt diet (14% CP and 2,750 kcal of ME) every day but at alternating a.m. and p.m. times. The amount of feed consumed in 4 h was fed twice in each 48-h period so that the feedings alternated between 16 and 32 h apart. This allowed for daily feeding while creating a type of anorexic period similar to that of the natural process. All 3 treatments produced completely successful molts with no egg production for up to 3 wk.

Although the previous studies showed that hens could be successfully molted without feed withdrawal, the results of the various productive parameters were somewhat inconsistent. It appears that this may be due to differing amounts of energy and CP being fed during the molt period, because each of these studies produced a molt by using various levels of different ingredients. These differences resulted in differing amounts of protein and energy offered to the hens during the molt resting period. The purpose of this study was an attempt to determine how much protein and energy is needed and when it is needed during the molt period to achieve optimal postmolt performance.

	MATERIALS AND METHODS

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 
Four strains of Leghorn hens at 66 wk of age were housed 3 per cage (464 cm²/hen) for a period of 24 wk in a light- and temperature-controlled facility. Hens utilized in the present trial were previously used to measure the effects of early beak trimming and to compare housing 3 and 4 hens per cage. The extra hen removed from the 4 bird cages was placed in another study if it was not needed to replace mortality in the 3-bird cages. A 2-wk acclimation period was provided before initiation of the molt. Each strain or diet treatment was replicated (pen) 16 times for a total of 288 hens per strain and 192 hens per treatment. The strains used were Bovans [14], Lohmann [15], Hy-Line W-98 [16], and Hy-Line W-36 [17]. They were fed either a low-energy (LO) 9.72% CP and 1,103 kcal/kg (500 kcal/lb) molt diet, a high-energy (HI) 9.72% CP and 1,433 kcal/kg (650 kcal/lb) molt diet, an intermediate (IM) energy and protein 11.86% CP and 2,105 kcal/kg (957 kcal/lb) molt diet, a standard (ST) 14% CP and 2,778 kcal/kg (1,263 kcal/lb) molt diet, a transition (TR) energy and protein 16.5% CP and 2,760 kcal/kg (1,255 kcal/lb) molt diet, and a commercial (CM) 17% CP and 2,845 kcal/kg (1,293 kcal/lb) layer diet (Table 1). The HI and LO diets were designed to simulate the anorexic state of molting birds described by Mrosovsky and Sherry [1]. The high fiber with low ME and CP allows full feeding with enough nutrients to maintain homeostasis without supporting egg production. The 6 dietary molt treatments were designed to determine the level of protein and energy needed and the periods of time they are needed during the initiation, resting, and recovery periods of the molt. Molt treatments (TRT) U and V were fed the LO and HI diets, respectively, for 2 wk (Table 2). That was followed by the IM, ST, and TR diets each for 2 wk. The W and X molt treatments were fed the LO and HI diets, respectively, for 3 wk, followed by the ST diet for 2 wk and the TR diet for 3 wk. Molt treatments Y and Z received the LO and HI diets for 4 wk, respectively, followed by the ST diet for 1 wk and the TR diet for 3 wk.

All diets were provided ad libitum. The layer diet (CM) was fed starting on d 56 of the molt. Water was provided ad libitum via nipple drinkers. Day length was reduced from 16 h per d to 11 h, commencing 2 wk before the initiation of the molt through d 32 of the molt. This allowed for the 5-h reduction in lighting needed to achieve the maximum reproductive response to day length reduction [18]. Day length was increased by 1 h on d 33 and 38, 0.5 h on d 43, and every fifth day thereafter until a 16-h d was restored at d 68 postmolt. Egg production and mortality were recorded daily. All hens were weighed initially and again at 4, 8, 12, and 24 wk of the trial. Twenty-five percent of the hens having BW closest to the mean in each treatment were designated as sample weight hens. Their BW was measured initially and weekly for the first 8 wk. Feed intake was measured weekly from wk 2 through 8 and every 4 wk thereafter. Orthogonal contrasts were established to evaluate the effect of time on different molting procedures. Data were analyzed using the GLM procedure [19]. Means found to be significantly different from each other were identified using Duncan’s multiple range test [20]. An arc sine procedure was applied to egg production data.

This trial was designed to study the energy and protein required by the hen during the rest and recovery period of the molt and how the results of these requirements affect the hen in the lay cycle. The effect of these variables occurred during the first 8 wk of the trial. To emphasize the particular week(s) when and to what extent these effects occurred, the tables consist of 2 parts, with the first 8 wk shown separately followed by all 6 periods of the trial to illustrate the total performance picture.

	RESULTS AND DISCUSSION

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 
Treatments
The diets contained different combinations of soybean hulls and wheat middlings that totaled from 70 to 80% of the diet. Some commercial operations may not be able to handle that level of these ingredients either in the mill or passage through the feeding system. It must be noted that full-fed molt diets must be fed in the form of mash to achieve an effective molt. Feeding it in the form of pellets or crumbles will cause overconsumption of the diet, which will defeat the low level of nutrient intake needed for a successful full-fed molt protocol [7]. Feed withdrawal periods have ranged from 14 to 16 d as recommended by Brake and Carey in 1983 [21] to 6 d by Ruszler in 1984 [18]. Ruszler [22] reduced the period to 4 d in 1996, which was followed by a 28-d period of increasing feed levels going from 25% of the maintenance needs of the hen up to 90% of its full production requirements. This more closely follows the natural pattern of feed intake for developing pullets than does full feeding after 14 d of total feed withdrawal [14, 15, 16, 17].

Feed Intake.
It appears that the high fiber content of the HI and LO ME diets initially suppressed feed intake during wk 1 and 2 (Table 3) when compared with wk 3 for TRT W and X or wk 3 and 4 for TRT Y and Z. Intake increased as the hens adapted to the feed over time as shown by TRT W and X or Y and Z. There was about a 50% increase in feed intake in these 4 treatments after the first 2 wk once the hens adapted to a molt diet that was less dense than their previous layer diet. There may have been a more gradual increase in feed intake during wk 2 over wk 1 which cannot be numerically determined, because the first feed measurement taken was at the end of wk 2. However, the suppression created by the LO ME diets containing more fibrous ingredients than the HI ME diets was significantly apparent during the first 2 wk. Biggs et al. [9] reported a 2-fold increase between wk 1 and 3 while feeding low-energy molt diets based on wheat middlings or corn gluten meal. They attributed it to either palatability or energy density. The suppression in this study may have also been due to palatability, because more of the HI diet was consumed during the first 2 wk (P 0.05) and feed intake was usually highest numerically each wk for diets with the higher levels of protein and energy. Feed intake during wk 3, 4, 6, and 7 of the trial was significantly different for the treatments. Feed intake for hens in TRT Y and Z appeared to be compensatory during wk 6 and 7. Hens in TRT Y and Z consumed less feed (P 0.05) cumulatively during the first 4 wk than hens on TRT U and V or W and X (50.3 vs. 54.7 or 56.1) but significantly more (101.7 vs. 97.5 and 99.2) during the second 4 wk of the trial. Because there was no period of feed withdrawal, there was no spike in feed consumption during wk 5 or 6 as is usually found with feed withdrawal molt programs when the hens return to full feed. Total feed intake was not significantly different at 8 wk or through 24 wk. Any productive performance differences after 8 wk appear to be due to the differences in ingredient intake during the first 7 wk of the molt.

CP.
The level of CP fed in work previously reported has been determined by dietary or ingredient levels used. No work has reported on the level needed to initiate a molt, maintain a proper rest period, or return to normal egg production postmolt. The length of the various periods of feed withdrawal was the primary method for generating a molt, which tended to preclude any need for knowledge about CP or ME levels, because feed withdrawal initiated the molt. Ruszler [23] reported in 1986 that 1.3 lb (590 g) of CP was needed to attain 50% egg production postmolt. Additionally, he reported that hens molted with a short fast (6 d) consumed 2.4 lb (1,089 g) of CP, whereas hens molted with a long fast (12 to 14 d) consumed 2.8 lb (1,270 g) of CP to reach peak production. Nonfasted molt programs may yield different values.

The consumption of CP in this study tended to follow that of feed intake. However, the significant differences between treatments are more clearly defined (Table 4). The initial HI ME treatments consumed significantly more CP than the LO treatments during the first 2 wk as a result of their increased feed intake. The same was generally true for the remainder of the trial. Hens in TRT Y and Z consumed significantly less CP (P 0.05) than hens in TRT U and V or W and X during the first 4-wk period (137 vs. 172 or 179 g of CP/bird) but consumed significantly more (465 vs. 427 or 454 g of CP/bird) during the second period. Total CP intake at 8 wk for hens in TRT W and X was 632 g/bird per week, which was significantly greater than hens in TRT U and V or Y and Z consuming 597 or 602 g/bird per week, respectively (Table 4). This difference was sustained, but not significantly, throughout the trial. The 4-d feed-restricted hens consumed a similar level of CP by 8 wk but 108 g of CP/ bird less CP at 24 wk than the full-fed molted hens. A mean of 562 g of CP/bird was consumed by the full-fed molted hens to achieve 50% production compared with the 4-d molted hens (620 g/bird). The 4-d molted hens needed 44 g/bird more than the full-fed hens to reach peak production (Table 4).

During the first 4 wk while on the HI and LO diets, hens fed the LO diets consumed significantly less ME than hens on the HI diets (Table 5) as a result of decreased feed intake (Table 3). However, once hens were fed diets with a higher nutrient density, those previously on the LO diet tended to eat more feed, resulting in a short period of a numeric increase in ME intake for each treatment. This may be considered somewhat compensatory, except it was not great enough in value or duration to affect the energy levels at 8 wk. By 8 wk, the total energy levels consumed by hens fed the LO diets (TRT W or Y) were lower (P 0.05) than those on the HI diets (TRT X or Z). The total energy consumed by TRT U was numerically lower than TRT V by 8 wk (Table 5). However, the differences observed at 8 wk had disappeared by 24 wk. The data indicate that a mean of 9,438 and 16,695 kcal of ME/hen is needed to achieve 50% and peak production, respectively, for the full-fed molt treatments studied. Both of these values are considerably less than the 10,836 kcal of ME and 17,565 kcal of ME per hen, respectively, consumed by hens on the 4-d molt, as reported previously. This is because hens on the 4-d molt procedure were consuming diets containing 1,260 kcal/lb (2,772 kcal/kg) for the first 5 wk and 1,272 kcal/lb (2,800 kcal/kg) thereafter. This may indicate that the 4-d molted hens consumed more energy than needed to achieve 50% production. However, if one compares only those treatments (U, V, W, X, and Z) that produced a similar number of eggs as the 4-d molt treatment, the mean level of energy for those 5 treatments is 16,739 kcal/lb at peak production, which is closer to the amount of energy consumed by the 4-d molted hens. A similar comparison involving TRT U and V or W and X appears in the total energy at 8 wk. The opposite response occurred with CP at the time when 50% production was reached. This leads to a potential conclusion that the proper level of ME during the first 8 wk of a molt is more critical in achieving an effective and profitable molt than is the level of CP. It is also possible that the levels of CP fed in this study were sufficient for body maintenance, and the times that it was fed coincided with the needs of the hens during the rest period and regeneration of tissues for egg production.

Mortality.
The level of mortality was not a factor in this study. Only 29 hens died or 2.5% over the 6 periods with 11 hens or 0.95% during the first period, 7 hens or 0.61% during periods 2 and 3 of the trial, and 11 hens or 0.95% during periods 4, 5, and 6. The numbers were randomly spread over the 6 treatments and 4 strains.

Economics.
The ingredient cost of feed was less (P 0.05) for hens in TRT Y and Z than in TRT U and V or W and X during the first period (Table 8). This is a reflection of the differences in nutrient density of the initial diets being fed. However, the ingredient cost of feed for hens in TRT Y and Z was higher than U and V or W and X (P 0.05) during the second period. This was due to the hens in TRT Y and Z eating as much as 4 g/bird more than the other hens in addition to the increased cost of ingredients during the second period. They apparently attempted to compensate for the limited amount of nutrients received in the first period. This allowed TRT U and V to show a lower cumulative ingredient cost (P 0.05) through periods 1 and 2 than TRT W and X.

Feed Intake.
The Hy-Line W-36 strain of hens consumed more feed (P 0.05) than the other strains during the first 2 wk (3 to 8 g/bird per d; Table 10). However, by wk 4, the Hy-Line W-36 hens were consuming 4 to 7 g/bird per day less than the other strains. This significant difference was probably due to the genetic trait of the strain of normally only eating about 100 g/bird per day, except during the postmolt, when it may consume up to 115 g/bird per day [17]. Although the Hy-Line W-36 hens did consume this higher level of intake during the fourth period, they did not maintain it. The TR layer diet in period 2 did not have enough energy per kilogram of feed to satisfy the dietary needs [20] of the Hy-Line W-36 hens, and they were not able to compensate for it later. They continued to consume 7 g/bird per day (P 0.05) less than the Lohmann and Bovans strains during periods 3 through 6. During that period, the Hy-Line W-98 strain consumed 3 g/bird per day more feed (P 0.05) than the Lohmann and Bovans strains. The performance of all strains was consistent with information found in the breeder management guides [17, 18, 19, 20].

BW.
Body weight changes were similar across all strains. Initial BW for Bovans, Hy-Line W-98, Lohmann, and Hy-Line W-36 were 1,700, 1,919, 1,737, and 1,678 g/bird, respectively. They lost 23.2, 25.8, 25.2, and 21.2% BW, respectively, by wk 4 and returned to 1,809, 2,032, 1,842, and 1,814 g/bird at 24 wk.

Economics.
The ingredient costs per hen based on the level of feed intake are listed in Table 11. Although the Hy-Line W-36 hens produced the fewest total eggs, they were efficient converters of nutrients into eggs. They were positioned third behind Bovans and Lohmann in cost per dozen eggs at 24 wk even though they laid the fewest eggs. Commercial flocks are usually profitable for at least 6 mo postmolt. If the present study had been carried out for 3 more additional periods to make the comparison with a commercial flock, the increased level of ME intake of the Hy-Line W-36 hens may have allowed their feed cost per dozen as well as total eggs/hen housed to no longer be significantly different from the others at that time.

	CONCLUSIONS AND APPLICATIONS

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 

1. The level of ME appears to have a stronger effect on productive performance than CP.
   
2. Between 540 and 576 g of CP per hen are needed to achieve 50% production, and 1,114 to 1,122 g are necessary to reach peak production for full-fed molted hens.
   
3. Between 9,294 and 9,823 kcal of ME per hen are needed to achieve 50% production, and 16,328 to 17,015 kcal are needed to reach peak production for full-fed molted hens.
   
4. A diet of 1,103 kcal/kg of fed for 4 wk is detrimental to overall productive performance.
   
5. Although TRT U (low energy, intermediate, standard, and transitional molt diets) had the lowest ingredient cost/dozen, TRT W (low energy, standard, and transitional molt diets) may be preferred because it had 1 less change in diets.
   
6. This study showed an increase of $0.01/dozen in ingredient costs for full-fed molting compared with a 4-d feed withdrawal.
   
7. The difference in ingredient cost per dozen between the most and least expensive treatments in this study would result in $2,124 savings in a flock of 120,000 hens.
   

	ACKNOWLEDGMENTS

 
We thank Brenda Caldwell, secretary, for technical assistance and Barbara Self, laboratory technician, for statistical and technical assistance (both in the Animal and Poultry Science Department, Virginia Tech).

	REFERENCES AND NOTES

TOP SUMMARY DESCRIPTION OF PROBLEM MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS AND APPLICATIONS REFERENCES AND NOTES

 

1. Mrosovsky, N., and D. F. Sherry. 1980. Animal anorexias. Science 207:837–842.[Abstract/Free Full Text]
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3. United Egg Producers. 2002. Molting. Pages 8–9 in Animal Husbandry Guidelines. United Egg Producers, Alpharetta, GA.
4. United Egg Producers. 2006. Molting. Pages 9–10 in Animal Husbandry Guidelines. United Egg Producers, Alpharetta, GA.
5. Anderson, K. E., and D. R. Jones. 2000. Review on the Theological, Philosophical and Physiological Effects of Fasting Across Species. California Egg Comm., Upland.
6. Ruszler, P. L., and L. R. Minear. 1997. Comparison of induced molts using periods of four vs. ten days feed withdrawal. Poult. Sci. 76(Suppl. 1):104. (Abstr.)
7. Minear, L. R. 1999. Southern States Res., Richmond, VA. Personal communication.
8. Biggs, P. E., M. W. Douglas, K. W. Koelkebeck, and C. M. Parsons. 2003. Evaluation of nonfeed removal methods for molting programs. Poult. Sci. 82:749–753.[Abstract/Free Full Text]
9. Biggs, P. E., M. E. Persia, K. W. Koelkebeck, and C. M. Parsons. 2004. Further evaluation of nonfeed removal methods for molting programs. Poult. Sci. 83:745–752.[Abstract/Free Full Text]
10. Ruszler, P. L., C. F. Honaker, L. R. Minear, and C. L. Novak. 2004. Comparison of four commercial molt programs with and without feed restriction procedures. Page 15 in Abstr. Southern Poult. Sci. Soc. US Poult. Egg Assoc., Atlanta, GA.
11. Ruszler, P. L., and C. L. Novak. 200521e. Determining protein and energy levels needed for full fed molting procedures. Poult. Sci. 84(Suppl. 1):80. (Abstr.)
12. Donalson, L. M., W. K. Kim, C. L. Woodward, P. Herrera, L. F. Kubena, D. J. Nisbet, and S. C. Ricke. 2005. Utilizing different ratios of alfalfa and layer ration for molt induction and performance in commercial laying hens. Poult. Sci. 84:362–369.[Abstract/Free Full Text]
13. Ruszler, P. L., and C. L. Novak. 2006. Feeding hens during alternating a.m. and p.m. time blocks to induce zero egg production during the molt. J. Appl. Poult. Res. 15:525–530.[Abstract/Free Full Text]
14. Bovans. 1991. Bovans White Management Guide. Centurion Poult. Inc., Bogart, GA.
15. Lohmann. 2002. Lohmann LSL-LITE Layer Management Guide. Lohmann Tierzucht Inc., Sycamore, IL.
16. Hy-Line International. 2001. Hy-Line Variety W-98 Commercial Management Guide 2001–2003. Hy-Line. Int., West Des Moines, IA.
17. Hy-Line International. 2000. Hy-Line Variety W-36 Commercial Management Guide 2000–2001. Hy-Line. Int., West Des Moines, IA.
18. Ruszler, P. L. 1984. The keys to successful force molting. Virginia Coop. Ext. Serv. Publ. 408–026 (revised), Blacksburg.
19. SAS Institute. 2001. SAS User’s Guide: Statistics. Version 8 ed. SAS Inst. Inc., Cary, NC.
20. Duncan, D. B. 1955. Multiple range and multiple F tests. Biometrics 11:1–42.[Medline]
21. 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. North Carolina Agric. Extension Serv., Raleigh.
22. Ruszler, P. L. 1996. The keys to successful induced molting of Leghorn-type hens. Virginia Coop. Ext. Serv. Publ. 408-026 (revised). Blacksburg.
23. Ruszler, P. L. 1986. Comparison of certain methods for induced molting of layers. Pages 17–33 in Proc. Maryland Nutr. Conf., Baltimore. Univ. Maryland, College Park.
24. Fontana, E. A., P. L. Ruszler, W. L. Beane, and V. Magar. 1991. The effect of two feed withdrawal and two corticosterone supplementation programs on overall performance, body weight, and reproductive organ weights of force-rested layers. Poult. Sci. 70(Suppl. 1):159. (Abstr.)
25. Ruszler, P. L., C. F. Honaker, and C. L. Novak. 2004. The comparison of two full fed molt programs with two commercial restricted fed molt programs. Page 15 in Abstr. Southern Poult. Sci. Soc. US Poult. Egg. Assoc., Atlanta, GA.

This Article Summary Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Novak, C. Articles by Ruszler, P. Search for Related Content PubMed Articles by Novak, C. Articles by Ruszler, P.