Ken W. Koelkebeck
Patrick E. Biggs
Carl M. Parsons
Department of Animal Sciences
University of Illinois
Urbana, IL, U.S.A.
Introduction
Induced molting of hens is a practice used by most commercial egg producers to extend the productive life of their hens. Typically, molting has been achieved by fasting hens for 10 days or more. This method has come under attack from animal rights groups who have pressured commercial egg producers and lawmakers to stop using induced molting programs that involve feed withdrawal. A number of studies have been conducted in an attempt to develop effective methods to molt hens without the use of feed withdrawal. Low-sodium diets (Nesbeth et al., 1976; Ross and Herrick, 1981; Whitehead and Shannon, 1974; Scheidler et al., 2002) and high Zn diets (Berry and Brake, 1987; McCormick and Cunningham, 1987) are two methods that have been researched extensively. However, neither of these alternative methods has been widely practiced in the industry. Zimmerman et al. (1987) studied the use of 10 and 15% guar meal in molt diets and obtained results that were favorable as an alternative to fasting. Keshavarz and Quimby (2002) evaluated the use of a diet containing grape pomace with added thyroxine and a high corn diet with or without thyroxine as alternatives to fasting. All of these treatments were found to be effective for induced molting.
In addition to the Scheideler et al. (2002) report, Scheideler and Beck (2002) published guidelines for using a non-fasting molt program. Their recommendation includes using a low energy high fiber type of ration which is also low in sodium. The recommended diets are essentially a corn, soybean meal, wheat middlings diet with no added salt. The energy levels range from 1233 to 1250 kcal/lb having .08 and .04% sodium.
Bell (2001) reported on a field experiment in which three commercial egg farms were selected to compare their traditional feed withdrawal molting program with one that did not include the removal of feed. The treatments consisted of: 1) hens fed a corn diet with supplemental minerals and vitamins but no salt, and 2) feed withdrawn from hens for 6 to 13 days followed by feeding a typical molt diet. These treatments lasted for 28 days after which time all hens were fed a standard layer diet. The results of this study indicated that molting hens using a feed removal method was superior to the no-salt continuous fed method, but excellent results did occur on one farm with the no-salt method.
We reported on results of several studies using non-feed withdrawal treatments (Koelkebeck et al. 2001; 2002). For the second study we evaluated eight treatments including the use of wheat middlings, a corn diet, wheat middlings in combination with corn, corn gluten feed, and distillers grain with solubles in comparison to a conventional 10-day feed withdrawal period. The complete postmolt production results are presented herein. In addition, partial results of another study in which we are further evaluating the efficacy of wheat middlings and to also examine raw and pelleted soybean hulls, alfalfa meal, corn and wheat middlings and raw soybean hulls combinations, and wheat middlings and rice hulls combination are reported herein [Funding for the research reported herein was provided by the United Egg Producers (UEP), Ridley Feed Ingredients, Inc., and the Midwest Poultry Consortium].
Materials and methods
Experiment 1
In this experiment 636 Single Comb White Leghorn hens of the DeKalb White Strain (69 weeks of age) were used. They were housed in a cage layer house of commercial design with water and feed provided ad libitum 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. 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.
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 1. On Day 11, the 10-day feed withdrawn hens were fed a 16% protein corn-soybean meal molt or a 94% corn diet, and then were given ad libitum access to this diet for 18 days (Table 1).
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 were fed ad libitum or free choice their diets for 28 days (Table 1). Hens on all treatments were fed a 16% protein layer diet after 28 days. The total length of the experiment lasted for 44 weeks (four weeks for the molt period and 40 weeks for the postmolt lay period).
Thus, the eight dietary molt treatments were:
- hens fed a 94% corn diet,
- hens fed a 94% wheat middlings diet,
- hens fed a 47.0% wheat middlings and 47% corn diet (50:50),
- hens fed a 71% wheat middlings and 23% corn diet (75:25),
- hens fed a 95% corn gluten feed diet,
- hens fed a 95% corn distillers grain with solubles diet,
- hens deprived of feed for 10 days, then fed a 16% protein corn-soybean meal molt diet, and
- hens deprived of feed for 10 days, then fed a 94% corn diet.
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 until 17 h per day was achieved.
Ovarian Regression
It was 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 three 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.
Egg Production and Stress
Performance data was measured for 44 weeks following the initiation of feeding the molt diets 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. 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 efficiency was calculated for Weeks 6 to 44. In addition, general physiological stress was determined by counting blood leukocytes and calculating the heterophil:lymphocyte ratio as described by McKee and Harrison (1995). An elevated ratio should indicate increased stress. Blood samples were obtained from the wing vein from one hen per replicate on Day 0, 10, and 28.
Statistical Analyses
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.
Experiment 2In this experiment, 576 Single Comb White Leghorn hens of the Hy-Line W-36 strain (67 weeks of age) were used. They were housed in the same facility as in Experiment 1, arranged and allotted per treatment in the same manner. The experimental molt diets are depicted in Table 2. The eight dietary molt treatments were:
- hens fed a 94% wheat middlings diet,
- hens fed a 95% raw soybean hulls diet,
- hens fed a 95% pelleted soybean hulls diet,
- hens fed a 98% alfalfa meal diet,
- hens fed a 47% raw soybean hulls diet and 47% corn diet,
- hens fed a 47% raw soybean hulls and 47% wheat middlings diet,
- hens fed a 47% wheat middlings and 47% rice hulls diet, and
- hens deprived of feed for 10 days, then fed a 16% protein corn-soybean meal diet.
The protocol for feeding the molt diets and withdrawing feed from the conventional molt treatment followed the same procedure as in Experiment 1. However, the hens fed the raw and pelleted soybean hulls diets and the alfalfa meal diet were switched to the 16% corn-soybean meal diet on Day 14 due to greater than anticipated body weight loss. All other diets were fed for 28 days, and then hens were fed a corn-soybean meal layer diet (Table 2). Egg production performance data were measured as previously described for Experiment 1. Physiological stress measurements were taken, but are not reported here. One week prior to the start of the experiment, the daily photoperiod was reduced to 10 h per day from 17 h. On Day 25 and 32, the photoperiod was increased to 12 and 13 h, respectively, and then increased 15 min per week until a 17 h daily photoperiod was achieved. The data reported herein is the four-week molt period and 20 weeks of the postmolt period.
Results and discussion
Experiment 1
Figure 1 and Table 3 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 71% wheat middlings / 23% (75/25) 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 4. 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 47:47% wheat middlings/corn diet, however, mortality for this treatment was not different (P > .05) for hens fed the 71:23% wheat middlings/corn diet or those fed the corn gluten feed diet.
Figure 2, Table 5, and Figure 3 shows the return to egg production from Weeks 5 to 44 following the molt period. The hens that were without feed for 10 days, then fed a corn-soybean diet had the highest egg production from Weeks 32 to 44, while those fed the 71:23% wheat middlings/corn diet had slightly lower egg production. Hens that were continuously fed the wheat middlings and corn gluten feed molt diets produced at a faster rate during Weeks 5 to 12 than those fed the corn diet continuously. It took hens that were fed the corn distillers grains with solubles the least number of days to reach 50% production (38; Table 5), whereas, hens that were deprived of feed for 10 days then fed the 8% protein corn diet reached 50% production in the most number of days (56; Table 5). The reason as to why the hens fed the distillers grains reached 50% production the least number of days is because they only reached a low of 30% production during the molt period. The hens fed the 71:23% wheat middlings:corn diet achieved the highest peak egg production. For overall egg production during the postmolt period (Weeks 5 to 44), those hens restricted feed for 10 days, then fed the 16% corn-soybean diet produced at the highest rate (71.5%) and those fed the 47:47% wheat middlings/corn diet produced at the lowest rate (61.5%). For Weeks 1 to 44, the hens fed the 71:23% wheat middlings:corn diet produced the greatest (65.8%). Figure 6 shows the cumulative hen-housed eggs per hen from Weeks 1 to 44. The greatest number of eggs produced per hen occurred for those hens feed restricted for 10 days, then fed the 16% corn-soybean meal diet (199.7), while hens fed the 47:47% wheat middlings:corn diet laid the least number of eggs per hen (174.4). Those fed the wheat middlings and 71:23% wheat middlings corn combination produced nearly as many eggs per hen (193.9) as the conventional molted hens.
In Table 6, 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.
In Table 7, layer feed consumption for Weeks 6 to 44 ranged from 24.6 to 25.7 lbs. of feed per 100 hens per day for all treatments. The best feed efficiency occurred for hens deprived of feed for 10 days, then fed the 16% protein corn-soybean meal diet (4.2 lbs./doz. eggs), with the poorest feed efficiency noted for hens continuously fed the 47:47% wheat middlings/corn diet (4.7 lbs./doz. eggs).
The data for egg weight, case weights, egg mass, and egg specific gravity is depicted in Tables 8 and 9. These data show that minor differences did occur. The heaviest eggs produced were from those hens fed the corn gluten feed diet. Table 9 shows that at the end of the postmolt production period there were no significant differences in egg specific gravity.
Table 10 depicts the economic comparisons between treatments for egg income minus feed costs for Weeks 1 to 44. These results indicate that the most profitable molting program occurred for those hens that had feed withdrawn for 10 days, and then fed the 16% corn-soybean meal molt diet. The next best profitable program was the one where hens were continuously fed the 71:23% wheat middlings:corn molt diet.
Tables 11 and 12 depict 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.
The effect of molting methods on blood heterophil:lymphocyte ratios is depicted in Table 13. These data indicate that there were no clear cut differences noted, however, hens fed the wheat middlings molt diet demonstrated a lower ratio on Day 10 than those hens on the other treatments.
Experiment 2
Figure 4 and Table 14 depicts the daily and weekly egg production during the 28-day molt period. As expected, the hens that were withheld feed for 10 days went out of production at a fast rate and stopped laying eggs by Day 5. Hens that were fed the pelleted and raw soy hulls, alfalfa meal, and raw soy hulls/wheat middlings combination went out of production nearly as fast as the feed withheld hens. Hens that were fed the wheat middlings, raw soy hulls/corn, and wheat middlings/rice hulls combination diets exhibited a slower drop in egg production. The hens fed the wheat middlings diet continued to lay at less than a 5% rate throughout the molt period compared to those feed withdrawn for 10 days and those fed the other diets which laid at a 1.5% down to 0%. These data are similar to the results obtained in Experiment 1 for the feeding of wheat middlings and the 10-day feed withdrawal treatments.
In Table 15, the initial body weight, 13- and 28-day body weights, and mortality is shown. Hens that were fed the raw soy hulls, pelleted soy hulls, and alfalfa meal for the first 14 days of the 28-day molt period lost considerable body weight (Table 15). This was due to the hens consuming very little feed in the first two weeks of the molt period which ranged from 15 to 47 g/hen/day (data not shown). It was consequently decided to feed these hens the 16% protein layer diet, so that extreme mortality would not occur. The hens fed the raw soy hulls/corn/wheat middlings diets and the wheat middlings/rice hulls diets lost 24 to 27% body weight by Day 28. A slight increase in mortality also occurred (Table 15).
Figure 5 shows that those hens fed the pelleted soy hulls, raw soy hulls/corn, and wheat middlings/rice hulls diets came back into egg production at a slower rate during Weeks 5 to 8 of the 20-week postmolt period. After Week 10, egg production was similar for all treatments. Hens that had feed withdrawn for 10 days reached 50% production the earliest (38 days, Table 16). Peak hen-day egg production ranged from 84 to 89% for all treatments and occurred during Weeks 10 and 11, except for hens fed the raw soy hulls/corn and raw soy hulls/wheat middlings diets which peaked during Weeks 13 and 14, respectively. Average egg production during Weeks 1 to 20 was significantly greater for hens fed the wheat middlings and alfalfa meal diets compared to the other treatments (Table 16). Again, these data are similar to the first study in the return to egg production. As far as cumulative hen-housed eggs per hen, the hens fed the alfalfa meal has laid the most up to 20 weeks (86.7 eggs per hen), with those hens fed the wheat middlings diet producing slightly less (85.7 eggs per hen) (Figure 6).
Feed consumption, feed efficiency, egg weights, and egg mass is depicted in Tables 17 and 18. During the Weeks 5 to 20 postmolt production period, hens fed the alfalfa meal, wheat middlings, and raw soy hulls diets exhibited the best feed efficiency (Table 17). The data obtained for egg weight, case weights, and egg mass indicate that hens deprived of feed for 10 days produced the heaviest eggs, but hens fed the wheat middlings diet produced the greatest egg mass (Table 18). In this experiment, egg specific gravity is being monitored, but no differences have been apparent to date (data not shown).
Finally, Table 19 depicts an economic comparison of the profit per hen-housed. These data reveal that hens fed the alfalfa meal and wheat middlings diet have produced the most profit during the first 20 weeks of the experiment. It remains to be seen whether this trend will continue to hold for the 20 more weeks of the experiment.
Conclusions and take home message
In summary, the studies reported on herein, add to the growing body of knowledge of using non-feed withdrawal molting programs. Whether it is a program which utilizes a no-salt added diet or alternative feed ingredients in a molt diet, acceptable postmolt performance may be achieved. In our work reported on here, the use of a wheat middlings diet, wheat middlings/corn combination diet, corn gluten feed diet, or other diets such as soy hulls and alfalfa meal may provide acceptable results. If the egg industry is forced to adopt molting programs which do not utilize feed withdrawal and alternative feed ingredients are used for a non-feed withdrawal molting program, then acceptable programs may be one which use feed ingredients that are low in energy, readily available, and low in cost. These programs would provide for acceptable postmolt performance, although, probably slightly lower than a conventional feed withdrawal molting program.
Acknowledgments
The authors wish to thank the United Egg Producers, Ridley Feed Ingredients, Inc., and the Midwest Poultry Consortium for their financial support of this research. We also wish to thank Robert Leeper, Chet Utterback, Steve Heffernan, Pam Utterback, Mike Persia, Janet Snow and Carlos Martinez.
References
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From Proceedings of the "Midwest Poultry Federation Convention", St. Paul, Minnesota, U.S.A.
