Spray Sanitizing Hatching Eggs

Shell surface contamination of the hatching egg is inevitable in the breeder house environment. Normally, hatching eggs are not immediately set in the incubators upon lay but are one to ten days old before being set. During hatching egg storage there will be multiplication of any bacteria already on the shell surface (see Table 1). The greater the number of bacteria on the eggs, the greater the chance of those bacteria invading the interior of the egg. Table 1. Effect of Egg Storage upon Shell Surface Contamination Day 1 of Storage Day 7 of Storage Day 14 of Storage Number of Bacteria/Egg 154,446 254,228 310,444 The goal of the breeder house manager is to use good management strategies to minimize shell contamination. These strategies include such practices as: Keeping nests clean. Keeping storage facilities clean. Collecting eggs frequently. Maintaining proper temperature and humidity in the egg room. In addition to good management practices, procedures for sanitizing shell surfaces can prevent microbial invasion if used properly. One method used extensively in the past was fumigating hatching eggs with formaldehyde gas after collection. An alternative to fumigation is spraying the shell surface with an egg shell sanitizer. Numerous sanitizers on the market have proven useful, but, to be effective, the sanitizer must be used correctly. Proper Selection and Dilution The use of an effective sanitizer is essential to minimize contamination of the shell surface. Different classes of sanitizers (Quaternary Ammonium, Phenolics, Peroxides, etc.) kill microbes in different ways. Therefore, to assure effective control, the specific procedures for each sanitizer must be followed meticulously. Some classes of sanitizers are more effective than others when used in adverse environmental conditions like poor water quality. A sanitizer used on the egg must be effective at controlling microbial populations yet not toxic to the developing embryo. The entire sanitizer formulation should be examined to assure that none of the other compounds in the formulation can have an negative effect. Even compounds which are normally used as a hatching egg spray can be toxic if they are used at a concentration greater than the manufacturer recommendation. Sanitizers have been evaluated for optimal dilution, and using a concentration above the recommendation could potentially harm the embryo. Care must also be exercised not to use a compound which can deter the movement of oxygen to the embryo through the shell. Correct Application Immediate application of the sanitizer as soon as the eggs are collected is of utmost importance. Failure to apply the sanitizer in a timely manner will allow bacteria an opportunity to enter the shell through the pores and reside in the shell membranes. There the bacteria will not be exposed to the sanitizer and can then cause contamination of the egg's interior. To kill as many organisms as possible all spray sanitizers need to be applied in a manner which will thoroughly wet the shell surface. If the spray is applied insufficiently on the egg shell surface it may not reach some organisms, or possibly only injure some which can usually recover if the proper conditions exist (see Table 2). Table 2. Total Bacteria Colonies on Shell Surface for Non-treated Controls and Eggs with Inadequate and Adequate Coverage of Sanitizer Non-Sanitized Controls Misting with Sanitation (Inadequate) Thorough Coverage with Sanitizer (Adequate) 121,263 colonies/egg 43,830 colonies/egg 331 colonies/egg Chemical egg sanitizers possess physical properties similar to those of household cleaners and disinfectants. For this reason, extreme care should be taken not to spill or splash the sanitizer in the eyes, on skin or on clothing. Implications of Improper Sanitizing Proper selection and use of a sanitizer is essential to good spray sanitation management and can prevent additional problems in the hatchery. Since most incubators have greater than a 40,000 egg capacity, thousands of eggs and chicks could become contaminated if an infected egg explodes, breaks or becomes cracked inside the incubator. The proper practice of good management strategies will prevent microbial outbreaks and aid in the production of quality chicks.

Essentials of a Hatching Egg Quality
Assurance Program

A Hatching Egg Quality Assurance Program (QAP) will be cost effective in preventing a loss of hatch for long periods of time and will help to maintain the quality of the chick placed in the field. A Hatching Egg QAP prerequisite is communication and the feeling of shared responsibility between the hatchery, breeder service, and broiler service.

The objective of a Hatching Egg QAP are to promote chick quality and to help the operation maintain optimal chick yield from the breeder house. A Hatching Egg QAP will require:

• The collection of data for evaluation of the conditions to which eggs are subjected.
• The utilization of the data to improve and maintain optimal conditions in the hatchery and to develop a profile of efficiency for each breeder flock.
• The routine administration of the program elements.
• Communication among the individuals involved.

Factors evaluated to obtain data are:

At the hatchery

• Inspection for cleanliness and sanitation, monitored by microbial plating.
• Vaccine mixing and handling with special emphasis on factors leading to heavy bacterial loads in chicks.
• Egg quality from the farm.
• Egg breakout.

At the farm

• Inspection of egg handling and storage conditions

At the Hatchery

The Hatching Egg QAP will be performed at different times and at different frequencies. Evaluation of cleanliness and sanitation should be performed only after clean-up has occurred. This will indicate the effectiveness of the current sanitation program. Try to work the inspection around the work schedule of hatchery personnel, beginning the inspection where the least activity is taking place. The inspection should be similar to the following.

Egg Room

In the egg room, the first items to check are the room temperature and humidity levels. The record of these measurements for the past several weeks should be reviewed. The room should be checked for general cleanliness in the following areas: walls, ceiling, floor, vents, ducts, fans, cabinets and shelves, filters, doors, and light fixtures. Findings should be recorded on a check list. Find five empty farm racks that the hatchery is returning to the breeder farms and check for cleanliness. Make a written record of the collected information.

Monitoring of bacterial contamination in the egg room should be routinely conducted with air plates or a mechanical air sampler. The monitoring of shell contamination is not necessary unless there is a severe contamination problem which requires quantifying to aid in problem solving. Total shell washes as described by Gentry and Quarles would aid tremendously in quantitatively following improvement in egg handling practices. All eggs have shell surface contamination unless they have been thoroughly sanitized. To roll an egg on an agar plate will not provide a meaningful value of bacterial contamination, and the use of egg washes as a routine procedure is time consuming.

A regular program of grading eggs which includes observations on the incidence of cracked, dirty, stained, and upside down eggs is helpful as is a record of egg age. If there appears to be a problem with excessive debris on the eggs or egg racks entering the hatchery, it may be helpful to have a compressed air hose handy to blow off the debris before bringing the racks into the egg room. If cracks become a problem, the source of the cracks may be determined by candling a sample of three hundred eggs on the farm and again at arrival in the hatchery. Hairline cracks in a flock greater than 45 weeks old can pose a problem.

Checking the internal egg temperature upon arrival of eggs at the hatchery may be advisable periodically, especially during the warmer months when pre-incubation is more likely to occur. However, during the cooler months the monitoring of internal egg temperature may not be critical.

Specific gravity determination on eggs arriving at the hatchery may be performed if a shell problem becomes apparent and there is a need to determine the effectiveness of the corrective action. Performing routine specific gravity measurements may have limited value if other egg quality checks which are less time consuming are being performed regularly.

Setter Hall

In the setter hall check for cleanliness in the following areas: doors, lighting, floors, ceilings, vents, ducts, air filters, and walls. Select two areas in the hall and monitor microbial contamination using air plates or a mechanical air sampler.

Check the setters visually for cleanliness in the following areas: floors, walls, ceilings, fans, fan boards, racks thermometers, doors, nozzles, exhaust ports, vents, ducts, tops, and control panels. The machines should be evaluated for microbial contamination in a minimum of five setters in each hall. Enter each one while leaving the machine running and use an air plate or mechanical sampler to monitor microbial contamination of the air in the center of each machine. Make sure all fans and alarms are on when you enter so that the incubator's environment is not disturbed. Check that the turners, humidifier nozzles, and the aerosol sanitizer nozzle are working properly.

Hatcher Halls

In the hatcher halls check for cleanliness in the following areas: doors, lighting, floors, ceilings, vents, ducts, air filters, and walls. Select two areas in the hall and evaluate for microbial contamination with air plates or a mechanical air sampler. The air samples should be taken before transfer is made, selecting a minimum of five hatchers per hall. As a follow-up, check on hatcher sanitation. Test five areas inside a hatcher using Rodac plates or swabs. Any of the following areas may be tested: walls, ceilings, doors, fan boards, fan guards, fan blades, nozzles, air intake ducts. To conclude the hatcher inspection, five hatching trays should be examined for cleanliness and dryness. Trays should also be checked for microbial contamination using Rodac plates or swabs.

It is important that the individuals who record wet and dry bulb temperatures communicate abnormal readings directly to the manager. Failure to communicate abnormal readings may result in lower chick quality or reduced hatch.

Chick Room

After being cleaned and disinfected the chick room is inspected in the following areas: walls, ceilings, floors, vents, ducts, fans, cabinets, shelves, filters, doors, and lighting fixtures. Microbial contamination is checked using surface swab or Rodac plate samples. Two samples should be taken from the chick belt, the Chick Go-Round and one sample should be taken from each chick slide. A sample from the sexing table is collected in hatcheries where applicable. Microbial contamination should be monitored in the air from two locations, the chick processing area and the chick holding area.

Vaccine Room

Examine the vaccine room for cleanliness in the following areas: walls, ceilings, floors, doors, vents, ducts, cabinets, shelves, filters, and lighting fixtures. Collect one air sample for microbial contamination monitoring in this room. With a sterile syringe, pull 0.5 cc diluent per bottle from three bottles mixed for the next day's usage and plate for microbial contamination.

Monthly records for vaccination misses per 1000, beaktrimming error percentage and vaccine dosage checks should be examined. Observe vaccine mixing and handling and check the following:

• Amount of time needed to thaw vaccine.
• Number of ampules thawed at one time.
• Temperature of thawing H₂O.
• Vials and tops rinsed with diluent.
• Length of time to use vaccine mixture.
• Use of protective gloves and face shield when handling vaccine.
• Small cups placed over aspirator bottles while in use (where applicable).
• Cleanliness of Marek's injectors.
• Frequency of vaccine bottle change (where applicable).
• Frequency of tubing changes.

Maintain a written record of this information.

Use a sterile syringe to collect 0.5 cc of Marek's vaccine mix per bottle from 3 bottles prior to use in the chick room and plate for monitoring microbial contamination. Collect Marek's vaccine samples from 50% of machines on an open system and 25% on a closed system. Have one dose of vaccine per machine injected onto a plate. Collect Beak-O-Vac samples (if used) from 10% of machines in the same manner. To monitor the spray cabinet, place a sterile plate in a chick box and activate the spray.

Tray Wash Room

Examine the tray wash room in the following areas for cleanliness: walls, ceilings, floors, vents, ducts, fans, filters, doors, and lighting fixtures. The access hallways should also be evaluated during the inspection for general cleanliness in these areas: walls, ceilings, floors, vents, ducts, fans, filters, doors, lighting and fixtures.

Chemical Storage Area

Check the Chemical Storage Area to evaluate for safety and proper handling. Containers should be properly labeled and evidence of spillage should be checked. Safety equipment such as goggles, gloves and rubber aprons should be readily available.

Chick Bus

Evaluate the Chick Bus for overall cleanliness and record observations. Areas evaluated should be floors, fans, wells, air vents, and windows.

Roof of the Hatchery

On the roof of the hatchery, check the evaporative coolers, making sure that pads and H₂O are clean, and that the pads are unobstructed by mineral deposits. Evidence of disinfectant present should be evaluated in coolers (foam). Record observations on a checklist.

Egg Breakout Program

It is critical that an egg breakout program be performed on a regular basis. Each flock should be examined by residue breakout at least once per month. If the situation warrants, fresh egg or candling breakouts may be performed. It is also important that the data collected from the breakouts be placed in a format that can be easily retrieved and the individual flock history can be referenced over time and compared to performance standards. The breakouts are time-consuming and are usually the first thing deferred when time is limited. However, breakouts are necessary to prevent deterioration of flock performance. A critical item often overlooked when performing breakouts is the number of eggs missing between the number set and the number in the hatching tray. It is extremely important that the chicks be counted out of each tray from which the residue is being examined to determine the true hatch of the tray. Failure to do so may skew the hatch assessment from the sample and cause you to look in an erroneous direction when problem solving. Additional information which should be obtained on hatch days is an assessment of the time of hatch, the duration and evenness of hatching time for the various flocks as well as chick quality factors.

Inspection for the proper operation of setters and hatchers should be made once per month or when in suspect of malfunction. A quality thermometer should be used to check the accuracy of the machine thermometers. Proper environmental settings in the rooms and operation of the hatchery ventilation system must be constantly monitored.

Discussion between the hatchery manager, assistant manager, and any other supervisory personnel of any problem areas found during the inspection is critical.

At the Farm

It is advisable that all farm egg rooms have a set of guidelines for cleanliness and standard operation. The egg room environment and breeder house nesting conditions should be inspected on a regular basis and a written record maintained.

Communication

A Quality Assurance Program is only as good as the effort that is put into maintaining it on a regular basis. There must be a commitment from all individuals involved to make it succeed. Regular Quality Assurance Meetings (1 or 2 per month) between the hatchery manager, breeder manager, and broiler service manager are a must. The meetings at times may include all or some of the breeder and service personnel. At these meetings, problems with breeder and broiler flock performance should be discussed to supplement the information gathered at the hatchery as well as chick necropsy records from the diagnostic lab, chick delivery records, and broiler house chick mortality records. These meetings must be entered into with the idea of cooperation and problem-solving; the meeting is not to be a forum to point blame in anyone's direction.

Induced Molting as a Management Tool
	Because of increasing economic pressures, the commercial egg industry must make maximum use of its resources. High interest costs and the need to lower production costs have led many enterprises to use induced molting programs. An induced molt causes all of the hens in a flock to go out of production for a period of time. During this time regression and rejuvenation of the reproductive tract occurs, accompanied by the loss and replacement of feathers. After a molt, the hen's production rate usually peaks slightly below the previous peak rate, and egg quality is improved.
	Molting and Egg Size
	For the egg marketer, induced molting offers a means of matching the egg supply with market conditions. Molted flocks produce a higher proportion of larger eggs than do first-cycle flocks (see Table 1). Periods when high prices or premiums are paid for the larger eggs (usually during the summer) favor molted flocks. Periods when the price spread between medium and large eggs is small (usually in the winter and spring) favor production from pullet flocks. Regardless of the time of year, if flock placements and molting schedules can be adjusted to take advantage of anticipated market conditions, molted flocks can produce greater returns per hen than single-cycle flocks.
	Hen Depreciation
	An even greater benefit of induced molting is that it reduces hen cost per dozen eggs because it lengthens the productive life of the hen. On the average, the cost of a pullet is spread over 20 dozen eggs, and a replacement flock is purchased annually. A molting program allows the pullet cost to be spread over an average of about 31 dozen eggs, and replacement flocks are purchased less often; typically, three times in five years. This difference may reduce egg production cost by more than 4 cents per dozen if pullet costs are high. When pullet prices are low, this savings may fall below 3 cents per dozen.
	Feed Efficiency
	As always, you can't get something for nothing. In the case of induced molting, a major disadvantage is that it leads to poorer feed efficiency. The amount that feed efficiency will drop depends on several factors, including strain, season, equipment and housing type, nutrition, and whether the molting technique is applied properly. If you calculate feed efficiency for a first-cycle flock by including the feed needed to grow a pullet and for the molted flock by including the molt feeds, then you will find that the molted flock will have a better overall feed efficiency. If, however, you calculate feed efficiency from 50 percent production for first-cycle and for molted flocks, you will find that the molted flocks have a poorer feed efficiency.
	Molting from the Producer's Viewpoint
	The decision whether or not to molt seldom rests with the contract egg producer. A successful molting program requires close cooperation between the production and marketing segments of the firm. At no point is this more important than at the laying house. A variety of induced molting methods are used today. Induced Molting of Commercial Layers outlines the most successful molting techniques available. Regardless of the prescribed methods and careful management of the hens and facilities.
	What to Expect from a Molting Program
	When you embark on an induced molting program you should be prepared for a number of changes. The most noticeable effect will be a reduction in the total number of eggs sold. You should expect an average of about 7 percent fewer eggs from molted flocks than from single-cycle flocks. For example, over a five-year period, five single-cycle flocks of 35,000 hens will produce about 3.5 million dozen eggs. Over the same period, three molted flocks of 35,000 hens will produce about 3.27 million dozen eggs, a difference of 230,000 dozen. This difference will obviously result in lower egg income unless specific arrangements are made to offset it. Another noticeable change involves egg quality (see Table 1). A reduction in grade-out is normal and requires the cooperation of the egg packer if the molting program is to be successful. What this means to the producer is that equipment maintenance, adjustment, and operation are even more critical with a molted flock than with a single-cycle flock to insure maximum egg yield. For example, a reduction in Grade A yield of 0.87 percent from a 35,000-hen flock can reduce income by over $280 per year. Thus, little differences can cost money, and daily attention to operating details is very important.
	Table 1. Typical Egg Sizes for Molted and Single-Cycle Flocks Percentage of Eggs Size or Quality Weight (oz. per dozen) Single-Cycle Flocks Molted Flocks Extra large over 27 30 39 Large 24 to 27 41 43 Medium 21 to 24 17 12 Small 18 to 21 8 5 Peewee under 18 4 1 Grade A -- 93 91 Checked and cracked -- 3 4
	A variety of adjustment methods have been used to offset the potential reduction in income. These include providing a cash payment to the producer during the time when the birds are out of production, increasing the contract price for eggs from the second laying cycle or decreasing the penalty for undergrade eggs. To the egg producer, a major advantage of induced molting is the reduction in time that the house is not producing income. Because flocks are replaced less frequently, the laying house will be empty less often, which can help smooth out the egg producer's cash flow. In summary, induced molting offers distinct economic advantages to the commercial egg industry. A molting program must be a team effort to be successful. Before deciding to initiate a molting program, carefully consider all costs and benefits. If your operation, facilities, labor, or management capabilities will not permit you to follow prescribed molting procedures strictly, you should consider other methods of reducing your production  Induced Molting of Commercial Layers Induced molting can be an effective management tool, enabling you to match egg production with demand and reduce bird cost per dozen eggs. Through an induced molt, the productive life of a flock can be extended to an age of 105 weeks. You can adjust the timing of a molt as part of a total profit plan that maximizes egg production over the life span of the hens and matches periods of highest egg production to periods of highest egg prices. The decision to molt a flock should be based on sound management principles and a thorough analysis of your management practices and economic situation. Refer to Induced Molting as a Management Tool, for a detailed discussion of molting program economics. The purpose of an induced molting program is to rejuvenate the reproductive system of the hen. For complete rejuvenation and optimum postmolt performance, the reproductive tract must experience complete regression - that is, egg production must completely stop. Complete regression results in the flock being totally out of production for 14 to 17 days. Because weight loss is closely associated with reproductive tract regression, body weight is closely monitored throughout a molt. The following factors, which are essential to a successful induced molt, are addressed in this guide: Age of the Flock Nutrition Lighting Flock History House and Equipment Design Season of the Year Variations Among Strains The procedures described for a successful six-week molt have been used extensively by the commercial layer industry. Much of the information in this guide is based on practical experience coupled with continuing research. Be sure to follow the recommendations closely. Deviating from the program can produce less than satisfactory results. The age of the flock has a profound influence on the success of an induced molt. Attempts to molt a flock less than 57 weeks old will be hampered by the hen's resistance to ceasing production. Some of the hens will likely not experience an adequate regression and rejuvenation of the reproductive tract. On the other hand, if the flock is more than 67 weeks old, the potential for restoring shell quality is greatly diminished, and the overall economic advantage of an induced molt is considerably reduced. The second laying cycle of the flock should end at 100 to 105 weeks of age. An induced molting program consists of three phases: (1) a premolt period, (2) a period of fasting and weight loss, and (3) a return to production after the fast. Premolt Phase Body Weight Sampling The success of a molt depends on accurate body weight sampling. The premolt weight of the hens is one of the most important pieces of information in the entire program. Do not cut corners in sampling the flock for body weight. One week before withdrawing feed, weigh all the birds in a cage at several locations throughout the house. Select sample cages from all decks, rows, and areas in the house. Mark these cages so that you can weigh the same birds for subsequent body weight samples. Targeting Body Weight Loss The amount of weight loss necessary for complete regression of the reproductive tract depends on the premolt weight of the hens. Table 1 indicates target weight loss for various premolt weight ranges. Many factors affect the method for achieving these goals. Read the fasting and weight-loss section of this guide closely. Table 1. Weight-Loss Targets Premolt Weight (pounds) Target Weight Loss (percent) Up to 3.6 30 3.6 to 3.8 33 Over 3.8 35   Lighting Program To cause the birds to stop laying abruptly, they should be "conditioned" by exposing them to constant light (24 hours per day) for seven days before withdrawing feed. The hens will then experience the maximum decrease in day length at the time of feed withdrawal. Premolt Calcium The addition of supplemental calcium to the feed during the final two days before the feed is removed improves the shell quality of the final eggs laid before production ceases. Adding 100 to 200 pounds of oyster shell per ton in addition to normal ingredients produces the best results. Alternately, oyster shell can be top-dressed in the house at the rate of 5 pounds per hundred hens. Fasting and Body Weight-Loss Phase Monitoring Weight Loss Weight loss must be closely monitored in the fasting phase and compared to the target body weight established in the premolt phase. Weigh all the hens in the same cages as were sampled during the premolt period. Measure body weights on the seventh and ninth day after feed withdrawal, and calculate the average weight loss per day. From this estimated rate of weight loss you can predict when the birds will achieve the target weight loss. Weigh the hens in the sample cages every other day until two cays before they are predicted to reach their target weight loss. Then weigh the sample birds every day. Seasonal Influences on Weight Loss A cool environment causes birds to lose weight more quickly. If weight loss occurs too rapidly, regression of the reproductive tract will not be complete. If a flock achieves the target weight loss before the twelfth day after feed withdrawal, the temperature within the house has been too low. In subsequent molts, steps should be taken to keep the temperature somewhat higher. For the flock that has lost weight too rapidly, begin limited feeding as soon as the target weight loss has occurred. Offer 15 pounds of Molt 1 feed (to be discussed later) per hundred hens per day until the twelfth day after feed withdrawal, at which time full feeding can resume. This procedure will maintain body weight and allow full regression of the reproductive system. Under normal circumstances this limited feeding is not required; it is described here only for situations when weight loss has been too rapid because of low house temperatures (less than 72F) or high air velocities (greater than 500 feet per minute). High house temperatures retard weight loss. If the target weight loss has not occurred by the eighteenth day after feed withdrawal, limited feeding should begin. Offer the birds 10 pounds of Molt 1 feed per hundred hens per day. Continue to monitor weight loss as described above. Housing and Equipment Influences on Weight Loss Many factors related to housing and equipment may cause poor uniformity in body weight. They include temperature differences and other ventilation problems, feed equipment problems, or localized problems with parasites or diseases. It is important to be aware of these factors. Within a house there may be zones that repeatedly produce birds with heavier or lighter weights. For example, hens in cages at different levels may consistently have considerably different weights. In such cases, hens in each cage level can be sampled for weight separately and a target weight loss established for each level. Those hens reaching the target weight loss first may be offered 15 pounds of feed per hundred hens per day to hold their weight constant until all hens have achieved the target weight loss. In other situations where it is not possible to feed the hens of differing weights separately, steps should be taken to eliminate the conditions that produce the nonuniformity. If the weight of birds in the flock is highly variable and an attempt is made to molt them as a single unit, the results may be less than satisfactory. Strain Influences on Weight Loss The North Carolina Layer Performance and Management Tests have shown that the rate of weight loss during a fast varies considerably with strain. Provided that the minimums discussed earlier are considered, strains should be allowed to lose weight at their own relative rate. The rate of weight loss has little or no influence on subsequent performance. Comparisons between strains without regard to these facts are not valid. Livability During Feed Withdrawal Livability should be more than 98 percent through the fasting period. There will be a notable decrease in livability as the flock approaches the target weight loss. Flock History and Livability If the flock has experienced some sort of challenge (such as disease, exposure to mycotoxins, or environmental stress) that has significantly affected egg production or livability in the first cycle, livability during the fasting period may decrease below 98 percent. The extent of the decrease depends on the nature and severity of the challenge and how long the flock has had to recover from the challenge. Before initiating a molt, examine the production records for the flock If there was a notable challenge during the last 8 to 10 weeks of the first cycle of the flock, expect livability during the molt to be lower than normal. If this challenge was severe and very recent, it might be wise not to molt the flock. Lighting Program Appropriate management of the lighting program for the flock is critical during the fasting and weight loss phase. The fundamental requirement is to provide constant or decreasing day length for 21 days after feed withdrawal. The best way to accomplish this depends on the house type and season. The following recommendations for closed housing assume absolute light control. If your house is not completely light tight, use the open housing recommendations. The lighting programs outlined in Table 2 begin on the day of feed withdrawal. In many parts of the United States the natural day length will far exceed the minimum day lengths suggested in Table 2. In midsummer, 30-minute increases in day length on days 21, 24, and 28 will result in extremely long day lengths after the molt. Make certain that the hens experience at least a 15-minute increase in day length on these days. Maximum day length does not need to exceed 16 hours for adequate stimulation. Table 2. Lighting Schedule For Open Houses Days after Feed Withdrawal For Closed Houses (Light Tight) Molts Starting June1-Nov. 30 Molts Starting Dec. 1-May 31 0-20 12 hour 12 hours or natural day length* on day of feed withdrawal, whichever is longer. Use natural day length* on 21st day or 12 hours, whichever is longer. 21 13 hours Increase day length by 30 to 60 minutes to total at least 13 hours. 24 13.5 hours Increase day length by 30 minutes if the increase on Day 21 was less than 60 minutes, to total at least 13.5 hours. 28 14 hours Increase day length by 30 minutes to total at least 14 hours. 35 Resume normal lighting program. Day length should be at least equal to that before the molt, totaling at least 15 hours. *Natural day length begins 30 minutes before sunrise and ends 30 minutes after sunset. Return to Production When the target weight loss has been achieved, the flock must be closely managed as feeding resumes and production begins. Returning the Fasted Flock to Feed Hens that have been fasted must never be returned immediately to full feed. For the first two days offer only 10 pounds of feed per hundred hens to prevent severe crop impaction. After this adjustment period, the hens should be given full feed. Nutrition During the Recovery Period Before the onset of production, the hens must be fed diets that promote rejuvenation of the reproductive tract and maximize feather growth. Two diets are recommended to meet these requirements. The exact formulation of these diets depends on availability of feedstuffs and feed prices. The recommended minimum levels of key nutrients are shown in Table 3. Table 3. Minimum Nutrient Levels of Recovery Diets Nutrient Molt 1 Diet Molt 2 Diet Crude protein 16% 17.5% Metabolizable energy 1,275 kcal/lb 1,300 kcal/lb Total sulfur amino acids 0.65% 0.70% Lysine 0.80% 0.95% Calcium 2.0% 3.75% Available phosphorus 0.4% 0.4% The Molt 1 diet should be fed from the time the flock is returned to feed until egg production reaches the 5 percent level. The Molt 2 diet should be fed from 5 percent to 50 percent production. When 50 percent production is reached the diet should provide daily intakes of 290 kcal of metabolizable energy, 610 mg total sulfur amino acids, 735 mg lysine, 3.8 g calcium, and 400 mg available phosphorus. These levels of nutrients should continue until peak production is reached. The flock should then resume the standard nutritional program used in the first production cycle. Housing Effects The difference in rearing and laying environments between open and closed housing produces fundamental physiological differences in birds. These differences cannot be explained solely by differences in light intensity. High air velocities resulting in "wind chill" contribute to this effect. One result is that flocks in closed housing return to production more slowly after molting than those in open housing. However, there is no corresponding difference in second-cycle productivity. Excellent performance can be attained with either type of housing. Care should be taken not to compare the performance of flocks housed in dramatically different environments without regard for the effects of those environments. Second-Cycle Performance The success of an induced molt is measured by the performance of the flock during the second laying cycle. No exact standards exist for second-cycle production. Field experience and recent North Carolina Layer Performance and Management Tests have produced general goals for molted layer performance. It is most accurate to express second-cycle performance in reference to the first-cycle production of the flock. Generally, molted flocks will lay 60 fewer eggs per hen housed, have a hen-day egg production rate 15 percent lower, and peak 10 percent below first-cycle performance. An example of these differences is presented in Table 4. Table 4. Typical Egg Production Rates for the First & Second Cycle of a Molted Flock Production Parameter First Cycle (20-62 weeks) Second Cycle (63-105 weeks) Eggs per hen housed 222 162 Hen-day production 78% 63% Peak production 90% 80%   Summary Throughout an induced molt it is essential to remember the underlying objective of the process. Maximum regression and rejuvenation of the reproductive tract will occur when the induced molting procedures described in this guide are conscientiously applied. Remember these important steps: Premolting Phase Assure proper body weight sampling. Establish proper body weight loss goal. Begin constant lighting seven days before withdrawing feed. Consider providing supplemental calcium. Fasting and Weight-Loss Phase Monitor weight loss very accurately. Be cognizant of other influences, such as housing and equipment, strain effects, and flock history. Use the proper lighting program. Return to Production Phase Never return birds to full feed immediately. Feed appropriate nutrient levels. Be aware of potential housing effects. Know what to expect during the second cycle.