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INTRODUCTION

Concern for the welfare of the hen during an induced molt has been expressed by animal activists groups, poultry scientists, and commercial poultrymen in recent years. Most commercial laying hen molting programs utilize some length of feed removal to initiate a molt. These practices have raised some questions and concerns by the general public and industry groups. The United Egg Producers (UEP) recently recommended that producers and university researchers should work together to develop alternative molting techniques that do not involve the use of feed removal to initiate a molt. In addition, McDonald's Corporation said they would require egg producers that supply their eggs (2.5% of total U.S. egg production) to no longer use feed withdrawal programs to initiate a molt (Anonymous, 2000a). This policy by McDonald's Corporation is now being enforced.

Currently, there are several researchers that are conducting studies that are evaluating the effect of molting commercial layers without the withdrawal of feed. One such study currently being done is by Don Bell at the University of California (Bell, 2001). In this study, three commercial egg farms were selected to compare their traditional molting program with one that did not require the removal of feed. The treatments consisted of: 1) hens fed 10 to 12 lbs. per 100 hens of a corn diet with dicalcium phosphate, limestone, and a vitamin-mineral pre-mix per day with no salt, and 2) feed withdrawn from hens for 6 to 13 days followed by feeding a molt diet. These treatments lasted for 28 days at which time all hens were fed a standard layer diet. Artificial lighting was reduced, then increased back to its original length at Day 28. The preliminary results of this study indicated that the first 4-wk mortality was higher in the no-feed treatment but total mortality was lower. Percent egg production during Weeks 2 to 4 were 0% for the no-feed method, but 1 to 7% in the no salt groups. In addition, the percent egg production was higher during Weeks 10 to 12 in the no feed groups. The results of this study indicated that molting hens using a feed removal method was superior to the no-salt continuous fed method, although, excellent results did occur on one farm with the no-salt method.

In addition to this study, we have conducted one experiment and are in the process of conducting another experiment in this area of research. The first study was sponsored by the California Egg Commission and the second ongoing study is being sponsored by the United Egg Producers. In the first study we wanted to evaluate the effect of several non-feed removal methods in comparison to a short feed removal period and a conventional feed removal period on long-term postmolt laying hen performance. For the second ongoing study, we are evaluating eight treatments including the use of wheat middlings, a corn diet, wheat middlings in combination with a corn diet, corn gluten feed, and distillers grain with solubles in comparison to a conventional 10-day feed withdrawal period. Thus, the purpose of both studies was to evaluate the effects of non-feed removal molting alternatives on long-term postmolt performance of laying hens.

MATERIALS AND METHODS

Experiment 1. In this experiment, Single Comb White Leghorn hens of the DeKalb White Strain (60 wk of age) were housed in a cage layer house of commercial design with water and feed provided for ad libitum consumption and exposed to a 17-h daily photoperiod prior to the start of the experiment. Prior to the initiation of the experiment, all hens were weighed and allocated to each treatment group according to equal body weights. Seven replicate groups of 12 hens each (4 adjacent raised wire cages, 30 x 46 cm, containing 3 hens per cage, i.e., 72 sq in per hen) were randomly assigned to each treatment.

A total of 336 hens were randomly assigned to four treatments, which consisted of birds fed a high corn molt diet or high wheat middlings molt diet and birds deprived of feed for 4 or 10 days. At the start of the experiment (Day 1), feed was withdrawn from the groups designated to be deprived of feed for 4 or 10 days. The birds in the other two treatments were fed their respective diets (1 or 2, Table 1). On Day 5, the 4-day feed withdrawn hens were given ad libitum access to the same corn molt diet as depicted in Table 1 (Diet 1). On Day 11, the 10-day feed withdrawn hens were fed the corn molt diet described in Table 1 (Diet 1). The hens deprived of feed for 4 or 10 days were fed the corn molt diet at a rate of 54 g per hen per day (12 lbs. per 100 birds per day) for the first two days following feed withdrawal to minimize overconsumption and crop impaction, and then were given ad libitum access to this diet for 22 or 16 days, respectively. These hens were then provided ad libitum access to the layer diet (Table 1). The hens that were not deprived of feed were fed ad libitum the corn or wheat middlings molt diets described in Table 1 (Diets 1 and 2) for 28 days, then fed the 16% protein layer diet (Table 1). The total length of the experiment was 44 weeks (four weeks for the molt period and 40 weeks for the postmolt lay period).

On Day 1 (the initiation of feed withdrawal or feeding molt diets), the daily photoperiod was decreased to 10 h. On Day 24 and 31, the daily photoperiod was increased to 12 and 13 h, respectively, then increased 15 min per week for the next four weeks. For the next six weeks, the photoperiod was increased 30 min per week until a photoperiod of 17 h was reached.

Performance data was measured for 44 weeks following the initiation of feeding the molt diet or feed withdrawal. Egg production and mortality were recorded daily. Egg weight, and egg specific gravity (using the flotation method with NaCl solutions varying in specific gravity from 1.056 to 1.096 in .004 increments), were measured on all eggs produced on 2 consecutive days each week for egg weight, and Weeks 6, 7, and 8 then monthly for egg specific gravity. Haugh units were measured from a one-day collection of six random eggs per replicate group monthly from Weeks 9 to 44. Egg mass was calculated for Weeks 6 to 44 using hen-day egg production and average egg weight. Feed consumption was measured weekly for the entire experiment and feed conversion was calculated for Weeks 6 to 44. Body weights of hens deprived of feed for 4 days were measured on Day 4, then all hens were weighed on Day 10 and 28. The economic implications of each treatment was evaluated by computing egg income minus feed costs.

Experiment 2. In this experiment 636 Single Comb White Leghorn hens of the DeKalb White Strain (69 weeks of age) were used. They were housed in the same facility as Experiment 1 and exposed to a 17-h daily photoperiod prior to the start of the experiment. Six replicate groups of 12 hens each (4 adjacent raised wire cages, 30 x 46 cm, containing 3 hens per cage, 72 sq. in. per hen) were randomly assigned to each treatment. Prior to the initiation of the experiment, all hens were weighed and allocated to each treatment group according to equal body weights.

 

At the start of the experiment (Day 1), feed was withdrawn from the groups designated to be deprived of feed for 10 days. The birds in the other six treatments were fed their respective diets immediately (corn diet, wheat middlings, corn gluten feed, corn distillers grains with solubles, Table 2). On Day 11, the 10-day feed withdrawn hens were fed a 16% protein corn-soybean meal molt or a 94% corn diet as in Experiment 1, then were given ad libitum access to this diet for 18 days (Table 2). The 16% protein molt diet is a very well balanced nutritional diet that will result in hens rapidly regaining their body weight and rapidly returning to egg production. The 10-day feed withdrawal and then feeding a 16% protein molt diet is a program used in many commercial operations. The hens that were not deprived of feed (Treatments 3-8) were fed ad libitum or free-choice their diets for 28 days. Hens on all treatments were fed a 16% protein layer diet after 28 days (Table 1). The total length of the experiment will last 44 weeks (four weeks for the molt period and 40 weeks for the postmolt lay period).

Thus, the eight dietary molt treatments were as follows:

1. Feed withdrawn for 10 days, then fed a 16% protein corn-soybean meal molt diet for 18 days
2. Feed withdrawn for 10 days, then fed a 94% corn diet for 18 days
3. Fed a 94% wheat middlings diet continuously for 28 days
4. Fed a 94% corn diet continuously for 28 days
5. Fed a 47.0% wheat middlings:47.0% corn diet continuously for 28 days (50:50)
6. Fed a 71% wheat middlings:23% corn diet continuously for 28 days (75:25)
7. Fed a 95% corn gluten feed diet continuously for 28 days
8. Fed a 95% corn distillers grain with solubles diet continuously for 28 days

On Day 1 (the initiation of feed withdrawl or feeding molt diets), the daily photoperiod was decreased to 10 h. On Day 24 and 31, the daily photoperiod was increased to 12 and 13 h respectively, then increased 15 min per week until 17 h per day is achieved.

Ovarian Regression. It is of interest to determine the degree of ovarian regression among treatments, particularly for the hens not deprived of feed compared to the 10-day feed withdrawn hens. Total or almost total ovarian regression is needed to obtain good long-term egg production and egg shell quality during the second production cycle. Therefore, an additional group of 12 hens (four adjacent cages containing hens hens per cage) were allocated to Treatments 1, 3, 4, 7, and 8 (n=60). To determine the regression in ovary and oviduct weights, three hens from each group were euthanized on Day 1, 10, 21 and 28. Ovary and oviduct weights were recorded and the data is presented as a percentage of body weight.

STATISTICAL ANALYSIS

All data were analyzed by analysis of variance procedures appropriate for a one-way completely randomized design with the Fisher's least significant difference test used to determine significant differences among treatment means (Steel and Torrie, 1980). For feed consumption during the molt period and postmolt lay period, data was recorded in g/hen/day, then extrapolated to lbs/100 hens/day. Thus, statistical comparisons were not included for these figures.

RESULTS AND DISCUSSION

Experiment 1. The decrease in daily hen-day egg production during the 28-day molt period is graphically shown in Figure 1 and the first 4 weeks is depicted in Table 3. Hens that were deprived of feed for 4 or 10 days went out of production by Day 5, and those fed the wheat middlings molt diet ceased egg production by Day 8. In contrast, hens which were fed the corn molt diet never went completely out of production, and were producing at a rate of 2.7% by Day 28 of the molt period. From Day 5 through 13, hens fed the corn molt diet produced significantly more eggs than those on the other three treatments. By Day 15, 12, and 23, hens fed the wheat middlings molt diet, deprived of feed for 4 or 10 days returned to egg production, respectively.

Table 4 depicts the initial, ending and final body weight loss and mortality during the molt period (Weeks 1 to 4). Hens that were deprived of feed for 4 or 10 days lost 11.1 and 22.0% body weight, respectively. Body weight loss at Day 28 was 10.2, 7.5, 8.6, and 8.0% for hens fed the corn and wheat middlings molt diet, or deprived of feed for 4 or 10 days then fed the corn molt diet, respectively. Mortality rate did not differ significantly between any treatment during the 28-day molt period.

In Table 5, the data representing the projected feed consumption converted to pounds per 100 hens per day reveals that those hens fed the wheat middlings molt diet consumed less feed during the first week than those fed the corn diet. After that, feed consumption for this treatment exceeded that for hens fed the corn diet during Weeks 2 to 4. Feed consumption for hens fed the wheat middlings molt diet was the highest of any treatment during Week 4. As might be expected, hens that were deprived of feed for 10 days consumed a high amount during Weeks 2 and 3. The reason that hens fed the wheat middlings molt diet consumed less feed than those fed the corn diet during Week 1 was probably because of the abrupt change to a low energy diet. The reason that hens fed the wheat middlings molt diet consumed more feed during Weeks 2 to 4 than those fed the corn molt diet is because of the low-energy and bulky nature of the wheat middlings molt diet. In addition, this indicated that this diet was quite palatable and not severely nutritionally imbalanced.

The return to egg production after the initiation of feeding the layer diet is graphically shown in Figure 2 and summarized in Tables 6 and 7. Postmolt egg production was generally higher for those hens fed the wheat middlings molt diet and 10-day feed removal treatments than for the corn and 4-day feed removal treatments. During Weeks 6 and 7 particularly, postmolt egg production was significantly higher for hens fed the wheat middlings molt diet than for hens fed the corn molt diet (Table 6 and Figure 2). Days to 50% egg production occurred first for the wheat middlings molt treatment with peak egg production being 90.7 and 89.6% for the 10-day feed removal and wheat middlings molt treatments. Postmolt hen-day egg production was significantly greater for hens deprived of feed for 10 days vs those fed the corn molt diet and deprived of feed for 4 days during Weeks 5 to 44 (Table 7). In addition, egg production was not different for hens fed the wheat middlings molt diet vs. those deprived of feed for 10-days and fed the corn diet. In addition, there were no differences in postmolt mortality between any of the treatments during Weeks 5 to 44 (data not shown). These results indicate that postmolt egg production of hens fed the wheat middlings molt diet equaled that for hens that were deprived of feed for 10 days.

Figure 3 shows the cumulative hen-housed eggs per hen for Weeks 5 to 44. This shows that hens that were deprived of feed for 10 days produced the most hen-housed eggs per hen up to 44 weeks (207), followed by 202 eggs per hen for hens fed the wheat middlings molt diet. Hens that were deprived of feed for 4 days and those fed the corn diet produced 180 and 171 eggs per hen, respectively.

The positive early postmolt egg production results noted with the wheat middlings molt diet treatment can be explained by the increase in layer feed consumption for that treatment during Weeks 5 and 6 (Table 8). After the hens were all fed the layer ration the significant differences between each treatment began to disappear as indicated by similar layer feed consumption for each treatment during Weeks 5 to 44 (Table 9).

Table 10 depicts the results for postmolt egg weight, case weight, egg mass, and feed conversion. These data show that no significant trends occurred for average egg weights. Postmolt egg mass and feed conversion was greater for hens fed the wheat middlings molt diet compared to those fed the corn molt diet and deprived of feed for 4 days then fed the corn molt diet. These results can be explained by the differences noted earlier for egg production and feed consumption.

Table 11 depicts the results for postmolt egg specific gravity. These data show that there were no significant effects of molt treatment on egg specific gravity towards the end of the postmolt production period.

Finally, Table 12 depicts the effect of the molt treatments on postmolt egg income minus feed costs for Weeks 1 to 44. Egg income minus feed costs were compared using the total number of eggs produced and total feed (molt plus layer) consumed for all hens in each treatment. The cost of each molt and the layer diets were calculated using appropriate feedstuff prices (Anonymous, 2000b). Egg income was based on a price of $.70 per dozen (Schrader, 2000). As noted in Table 12, the hens which were deprived of feed for 10 days had the highest egg income minus feed costs, with hens fed the wheat middlings molt diet producing the second highest profit.

Experiment 2. Figure 4 and Table 13 depicts the decrease in daily egg production during the 28-day molt period. Hens that were deprived of feed for 10 days reached 0% production by Day 6. Those hens that were fed the 16% protein molt diet returned to production by Day 23 of the molt period, while those fed the corn diet after the 10-day feed withdrawal period came back into production by Day 24 (1.4%). None of the other six treatments produced total cessation of lay, however, those hens fed the high wheat middlings molt diet reached a low of 2.8% on Day 12 and was at a 6.9% production by Day 28. Similar egg production trends were seen for hens fed the 75% wheat middlings/25% corn diet and those fed the corn gluten feed diet. The lowest daily production was .6% for hens fed the corn diet, but overall this treatment did not produce a dramatic reduction in egg production as much as the wheat middlings and corn gluten feed molt diets. Hens fed the corn distillers grain with solubles did not dramatically decrease in egg production compared to the other continuous fed diet treatments. Hens that were deprived of feed for 10 days reached 0% production during Week 2 and 3 and those fed the high wheat middlings diet reached 6.5% by Week 2.

Body weight loss and mortality during the molt period is depicted in Table 14. Hens that were deprived of feed for 10 days and fed the 16% protein molt diet or 8% protein corn diet lost 24.9 and 27.1% body weight, respectively. Hens that were continuously fed the corn, wheat middlings, corn-wheat middlings combinations, or corn gluten feed lost body weight in the range of 18.4 to 13.8%, with no significant weight loss between treatments at Day 28. However, hens continuously fed the corn distillers grain with solubles lost the least amount of body weight by Day 28 (9.8%). Mortality during the molt period was highest for hens fed the 50/50 wheat middlings/corn diet, however, mortality for this treatment was not different (P > .05) for hens fed the 75/25 wheat middlings/corn diet or those fed the corn gluten feed diet.

In Table 15, feed consumption during the molt period showed that hens continuously fed the wheat middlings molt diet consumed the least of any continuous fed diet group during the first week, then dramatically increased consumption of this diet the next three weeks. These data agree with that reported for Experiment 1. In addition, the feed consumption trend was nearly the same those hens continuously fed the corn gluten feed.

Table 16 and 17 depicts the data for ovary and oviduct weight. Both tables reveal that there was a trend for hens continuously fed the wheat middlings or corn gluten feed diets to exhibit ovary and oviduct weight regression. As might be expected, ovary and oviduct weight showed some regression in weight for hens deprived of feed for 10 days, then fed the 16% protein molt diet.

SUMMARY

In summary, the results of this study indicate that feeding a high wheat middlings diet, wheat middlings and corn combination diets, or a corn gluten feed molt diet to initiate a molt in commercial layers may be an effective alternative to traditional feed removal methods. The feeding of a high wheat middlings molt diet particularly in the first study, and the feeding of this diet or a corn gluten feed diet seemed effective in producing a cessation of lay and good comparable production performance compared to conventional feed withdrawal methods. In addition, the continuous feeding of a high wheat middlings molt diet to initiate a molt, did not negatively affect egg shell quality as measured by egg specific gravity in the latter stage of the postmolt egg production period. In conclusion, if the commercial egg industry is forced by animal welfare/rights pressures to move towards using molting programs which utilize a non-feed removal method, then feeding a wheat middlings, corn-wheat middlings combination, or corn gluten feed diet to induce a molt might be considered.

REFERENCES

Anonymous, 2000a. McDonald's targets the egg industry. Egg Industry. Vol. 105, No. 10, pp. 10-13.

Anonymous, 2000b. Feed ingredient market. Feedstuffs. Vol. 72, No. 26, July 2000.

Bell, D.D., 2001. Flock-Friendly Molting Methods - Alternatives to Feed Removal. Cornell Poultry Conference, Cornell, New York. June 20, 2001

Schrader, L.F., 2000. Schrader's egg price memo. United Voices Newsletter. United Egg Producers, November 20, 2000.

Steel, R.G.D., and J.H. Torrie, 1980. Principles and Procedures of Statistics: A Biometrical Approach. 2nd ed. McGaw-Hill Book Co., New York, NY.