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Comparison of Two Nesting Materials for Broiler Breeders1,2
Comparison of Two Nesting Materials for Broiler Breeders1'2 j . BRAKE
Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication April 22, 1985)
INTRODUCTION A number of nesting materials have been used for the production of eggs. The preference of the hen for these various materials has been found to vary significantly. White Leghorn and New Hampshire pullets were found to prefer wood shavings to rice hulls, almond shells, silica pellets, and Douglas fir bark cork (Hansen et al, 1948). Siegel and Howes (1959) found differing preferences with White Rock pullets for wood shavings, calcined clay, hay, and sugar cane materials but doubted that this would make any appreciable difference in performance if the entire pen was provided with only one material. Their work indicated that proper maintenance of the nest material affected performance to a greater degree than the material. The incidence of floor eggs has also been found to be affected by nest material ranging from 2% for wood shavings to 10% for corn cobs (Daly et al, 1964). Furthermore, strains are known to vary in nest-site selection (Appleby et al, 1983, 1984) which might affect preference for various nesting materials. Astroturf®, an alternate artificial nest pad material, has been developed for use in broiler breeders for both conventional and automatic
'Paper No. 9851 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. 2 Trade names in this publication do not imply endorsement of the products mentioned nor criticism of similar products not mentioned.
nests. The preference for this material by broiler breeder hens, when compared to wood shavings, has not been determined. More importantly, the effect of these nest materials on performance has not been investigated. The objective of the present study was to determine the relative preference for and performance of broiler breeders exposed to either wood shavings or nest pads. An additional objective of this study was to investigate factors which might modify these effects. MATERIALS AND METHODS Trial 1. Broiler breeders (Arbor Acres X Arbor Acres) were grown according to breeder recommendations for fall-hatched birds. The birds were housed in a 2/3-slat breeder house at 18 weeks of age. Details of the experimental facility and management have been previously described (Brake et al, 1984). The male and female broiler breeders were assigned at random to 16 replicate pens with 60 females and 6 males/pen. Egg production was initiated at 25 weeks of age. Each pen was equipped with a 12-hole galvanized metal nest box. Half of the individual nests in each box was supplied with pine shavings and half were supplied with Astroturf® artificial nest pads (Monsanto Co., St. Louis, MO). The pads were partially covered with shavings to mimic commercial practices during the initial 4 weeks of the study. The arrangement of nest material was alternated such that all nest positions, with respect to position relative to slats and level in the box,
2263
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
ABSTRACT The performance of broiler breeders, when exposed to either shavings or artificial nest pads and factors affecting nest preference, were studied in four trials. When given a choice, hens preferred shavings to nest pads but eggs laid on nest pads exhibited reduced contamination. When exposed to either material exclusively, hens laid fewer floor eggs and exhibited increased hatch of fertile eggs (percent) in the presence of nest pads. Painting galvanized nests flat black reduced preference regardless of nest material. Placing the artificial nest pad over a concave rather than flat bottom in the nest increased preference. (Key words.- nest material, broiler breeders, hatchability, behavior) 1985 Poultry Science 64:2263-2266
2264
BRAKE
data was subjected to arcsin transformation prior to analysis. Statements of statistical significance were based on P<.05. As egg production was presumed to be similar in all pens and comparable among pens at various ages, week of production was omitted as a factor (Hurnik et al, 1973). RESULTS The fertility of eggs laid on either nest material in Trial 1 did not differ (Table 1). Hatch of fertile eggs and classes of embryonic mortality did not differ significantly. However, hatch of fertile eggs and early deads approached significance (P<.10). A significant reduction in contamination in eggs laid on nest pads was observed (Table 1). There was a significant difference in preference due to nest material. When not given a choice of nest material (Trial 2), broiler breeders did not differ in egg production or feed conversion (Table 2). Egg weight, egg specific gravity, shell weight and percent shell did not differ (data not shown). However, significantly fewer floor eggs were produced in pens supplied with nest pads as the sole nesting material (Table 2). Fertility did not differ between pens supplied exclusively with either nest material, but eggs from pens with nest pads exhibited significantly increased hatch of fertile eggs, and decreased late dead and pipped eggs (Table 2). Hens exhibited a preference for the unpainted nest (Table 3) when given a choice of either an unpainted galvanized metal nest or a
TABLE 1. Effect of nest material on fertility and hatchability of broiler hatching eggs (Trial 1) Nest material Parameter
Nest pad
Fertility, % Hatch of fertile eggs, % Early dead, % Late dead, % Pipped, % Contaminated, % Average eggs laid/nest/
95.1 ± 91.2 ± 3.7 ± 3.2 ± 1.4+ .6± 12.7 ±
.5a' .4a .3a .3a .2a .lb .3b
' Means which possess different differ significantly (P<.05).
Shavings 96.1 90.2 4.3 3.5 1.5 1.2 18.3
± ± ± ± ± + ±
.4a 5a 3a 3a 2a la 3a
superscripts
1 Mean ± SE for 3600 total eggs collected from 8 replicate pens per mean over the entire trial.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
were represented equally. This arrangement was designed to negate positional effects (Hurnik et al, 1973). The number of eggs laid in each individual nest during 29, 33, 37, 4 1 , 45, 49, 5 3, 57, 61, and 65 weeks of age were recorded and collected separately. These eggs were sorted according to nest material on an individual pen basis. Forty-five eggs from each nest material type from each pen were set in a Jamesway 252B incubator (Butler Manufacturing, Ft. Atkinson, WI). Floor eggs were not set. Hatchability was determined, and all unhatched eggs were examined macroscopically to measure fertility, stage of embryonic mortality, and incidence of contamination. Trial 2. Broiler breeders (Hubbard X Hubbard) were grown according to breeder recommendations for fall-hatched birds. The birds were housed in a 2/3-slat breeder house at 20 weeks of age. Birds per pen and details of housing were identical to those of Trial 1. Egg production was initiated at 27 weeks of age. Four pens were equipped with nest pads as the sole nesting material, and four pens were equipped with pine shavings as the sole nesting material. Nest pads were covered with shavings at the initiation of the study. The number of nest-laid eggs and eggs laid on the floor and slats were determined every 4 weeks as in Trial 1. Fertility and hatchability was determined as in Trial 1. Trial 3. An additional two pens from the flock (Trial 2) were equipped with shavings and two pens were equipped with nest pads. Half of the individual nests were painted black and the remaining nests were left as unpainted galvanized metal. The nests were painted on an alternate basis such that all positions were represented equally for all treatments. Eggs laid per nest were determined as in Trial 1. Trial 4. An additional two pens from the flock (Trial 2) were equipped solely with nest pads. Half of the individual nests possessed a flat bottom as normally found, and the bottom of the remaining nests were modified to provide raised sides to form a concave bottom onto which the nest pad was fitted. The nests were again arranged such that all positions were represented equally for nest bottom type. Eggs laid per nest were determined as in Trial 1. Statistical Analysis. Data were subjected to either two-way or one-way analysis of variance with differences among means partitioned by Duncan's new multiple range test where appropriate (SAS Institute, 1982). Percentage
BROILER BREEDER NESTING MATERIALS TABLE 2. Effect of nest material on broiler breeder egg production characteristics* and fertility and hatchability2 (Trial 2) Nest material Parameter
Nest pad 148.01 3.94 6.94 95.46 93.40 4.24 1.54 .49 .56
± 4.22 ± ,14a ± 1.21° ± 1.02 a ± .83a
145.74 3.97 10.01 95.98 91.21
.60a .35b .17b .22a
4.11 2.94 1.39 .63
' Means which possess differ significantly (P<.05).
different
a
± 1.31 ± .05a + 1.23a ± .88a ± .78° .69a .40a ,42a .21a
± ± ± ±
superscripts
1 Mean ± SE for 4 replicate pens for 37 weeks of production. 2 Mean + SE for 1800 total eggs collected from 4 replicate pens per mean over the entire trial.
nest painted flat black. The interaction of nest color and nest material was significant. The shape of the bottom of the nest into which the nest pad was placed also significantly affected the preference. Hens laid more eggs in nests which had concave bottoms than nests which had flat bottoms (Table 4). DISCUSSION Egg laid on nest pads exhibited significantly increased hatchability in Trial 2 and a numerical increase (P<.10) in Trial 1. This was due to
TABLE 3. Effect of nest material and color of nest on nesting characteristics of broiler breeders (Trial 3) Color of nest Nest material
Flat black
Nest pad 16.84 ± . 7 6 ' Shavings 18.37 t .86 X 17.61b
Nest bottom
Eggs laid/nest/week
Flat Concave
17.33 ± . 8 1 b ' 20.90 ± 1.03 a
' Means which possess differ significantly (P<.05).
different
Shavings a
± ± ± ±
TABLE 4. Effect of shape of nest bottom supplied with nest pads on nesting characteristics of broiler breeders (Trial 4)
Unpainted (metal gray) 19.18 ± . 6 4 2 0 . 6 3 ± .88 19.90a
' Means which possess differ significantly (P<.05).
different
X 18.01a 19.50a
superscripts
1 Mean ± SE number of eggs laid per nest per week in each nest of a 12-hole nest box.
superscripts
'Mean ± SE number of eggs laid per nest per week in each nest of a 12-hole nest box.
a significant reduction in late dead and pipped eggs in Trial 2. A similar pattern was not observed in Trial 1 where a significant decrease in contaminated and a numerical decrease (P<.10) in early dead eggs was observed. This was probably due to inherent differences between the two flocks. When given a choice, hens in Trial 1 preferred shavings as a nesting material. However, when allowed to lay in pens equipped with either shavings or nest pads, broiler breeders laid significantly fewer floor eggs with nest pads in the nests. This was not attributable to lower egg production. These effects may be due to reduced broodiness in the pens equipped with nest pads. This would reduce nest setting time and provide more space for laying. This may also explain the differences in embryonic mortality. Similar results have been observed in turkeys (Christensen, personal communication). There has been a common perception among poultry producers that hens do not lay well on artificial nest pads. The data of Trial 1 supports this hypothesis. However, the data of Trial 2 argues against this hypothesis. Therefore, the examination of factors which may promote nesting on nest pads could prove beneficial. Hens preferred unpainted galvanized nests rather than nests painted flat black regardless of the nesting material. Hurnik et al. (1973) found a preference for unpainted galvanized nests when compared to nests painted blue, green, yellow, or red. The general perception that hens prefer dark areas in which to lay has not been supported in other studies as well (Appleby et al, 1984). Wood-Gush and Murphy (1970) also reported that Brown Leghorns exhibited no preference for dark nests unless they had previous experience with such. Most nests which employ nest pads possess a
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
Eggs/hen housed F e e d / d o z e n , kg Floor eggs, % Fertility, % Hatch of fertile eggs, % Early dead, % Late dead, % Pipped, % Contaminated, %
2265
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BRAKE
ACKNOWLEDGMENTS
Appreciation is expressed to Monsanto Company, St. Louis, MO for providing the Astroturf® and other financial assistance. The excellent supervision of animal care, data collection for the preference studies, and incubation procedures by James Parsons and statistical assistance of Susan Creech are appreciated.
REFERENCES Appleby, M. C , H. E. McRae, I.J.H. Duncan, and A. Bisazza, 1984. Choice of social conditions by laying hens. Br. Poult. Sci. 25:111-117. Appleby, M. C , H. E. McRae, and B. E. Pietz, 1983. The effect of light on the choice of nests by domestic hens. Appl. Animal Eth. 11:249—254. Brake, J., J. F. Ort, T. A. Carter, and W. R. Campbell, 1984. Effect of the insect growth regulator CGA-72662 (Larvadex®) on broiler breeder production, hatchability, and subsequent chick performance. Poultry Sci. 63:910—916. Daly, D. W., Jr., D. H. Sherwood, and T. B. Morris, 1964. Influence of various nesting materials on number of floor eggs and cracks. Poultry Sci. 43:1311. (Abstr.) Hansen, R. S., G. E. Bearse, and L. R. Berg, 1948. Bird preference for and comparative egg soilage on various nesting materials. Poultry Sci. 27:666. (Abstr.) Hurnik, J. F., F. N. Jerome, B. S. Reinhart, and J. D. Summers, 1973. Colour as a stimulus for the choice of the nesting site by laying hens. Br. Poult. Sci. 1 4 : 1 - 8 . SAS Institute, 1982. SAS User's Guide: Basics. Inst. Cary, NC. Siegel, P. B., and C. E. Howes, 1959. A comparison of various poultry nesting materials. Poultry Sci. 38:1247. (Abstr.) Wood-Gush, D.G.M., 1971. The Behavior of the Domestic Fowl. Heinemann Educational Books, Ltd., London, England. Wood-Gush, D.G.M., and L. B. Murphy, 1970. Some factors affecting the choice of nests by the hen. Br. Poult. Sci. 11:415-417.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
flat bottom. However, it has been reported that the domestic fowl gathers nesting material around her sides when laying and often throws shavings onto her back (Wood-Gush, 1971). The concave nests of Trial 4 were intended to mimic this nest-building effect. The presence of a depression around the hen may account for the preference of concave over flat nest bottoms. These data demonstrate that preferences exhibited by broiler breeder hens when given a choice do not necessarily manifest themselves when a choice is not available. Factors such as nest color and shape also affect nest preference. Nesting remains a complex problem which requires further investigation to successfully automate egg collection in broiler breeders.
Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27695-7608 (Received for publication April 22, 1985)
INTRODUCTION A number of nesting materials have been used for the production of eggs. The preference of the hen for these various materials has been found to vary significantly. White Leghorn and New Hampshire pullets were found to prefer wood shavings to rice hulls, almond shells, silica pellets, and Douglas fir bark cork (Hansen et al, 1948). Siegel and Howes (1959) found differing preferences with White Rock pullets for wood shavings, calcined clay, hay, and sugar cane materials but doubted that this would make any appreciable difference in performance if the entire pen was provided with only one material. Their work indicated that proper maintenance of the nest material affected performance to a greater degree than the material. The incidence of floor eggs has also been found to be affected by nest material ranging from 2% for wood shavings to 10% for corn cobs (Daly et al, 1964). Furthermore, strains are known to vary in nest-site selection (Appleby et al, 1983, 1984) which might affect preference for various nesting materials. Astroturf®, an alternate artificial nest pad material, has been developed for use in broiler breeders for both conventional and automatic
'Paper No. 9851 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. 2 Trade names in this publication do not imply endorsement of the products mentioned nor criticism of similar products not mentioned.
nests. The preference for this material by broiler breeder hens, when compared to wood shavings, has not been determined. More importantly, the effect of these nest materials on performance has not been investigated. The objective of the present study was to determine the relative preference for and performance of broiler breeders exposed to either wood shavings or nest pads. An additional objective of this study was to investigate factors which might modify these effects. MATERIALS AND METHODS Trial 1. Broiler breeders (Arbor Acres X Arbor Acres) were grown according to breeder recommendations for fall-hatched birds. The birds were housed in a 2/3-slat breeder house at 18 weeks of age. Details of the experimental facility and management have been previously described (Brake et al, 1984). The male and female broiler breeders were assigned at random to 16 replicate pens with 60 females and 6 males/pen. Egg production was initiated at 25 weeks of age. Each pen was equipped with a 12-hole galvanized metal nest box. Half of the individual nests in each box was supplied with pine shavings and half were supplied with Astroturf® artificial nest pads (Monsanto Co., St. Louis, MO). The pads were partially covered with shavings to mimic commercial practices during the initial 4 weeks of the study. The arrangement of nest material was alternated such that all nest positions, with respect to position relative to slats and level in the box,
2263
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
ABSTRACT The performance of broiler breeders, when exposed to either shavings or artificial nest pads and factors affecting nest preference, were studied in four trials. When given a choice, hens preferred shavings to nest pads but eggs laid on nest pads exhibited reduced contamination. When exposed to either material exclusively, hens laid fewer floor eggs and exhibited increased hatch of fertile eggs (percent) in the presence of nest pads. Painting galvanized nests flat black reduced preference regardless of nest material. Placing the artificial nest pad over a concave rather than flat bottom in the nest increased preference. (Key words.- nest material, broiler breeders, hatchability, behavior) 1985 Poultry Science 64:2263-2266
2264
BRAKE
data was subjected to arcsin transformation prior to analysis. Statements of statistical significance were based on P<.05. As egg production was presumed to be similar in all pens and comparable among pens at various ages, week of production was omitted as a factor (Hurnik et al, 1973). RESULTS The fertility of eggs laid on either nest material in Trial 1 did not differ (Table 1). Hatch of fertile eggs and classes of embryonic mortality did not differ significantly. However, hatch of fertile eggs and early deads approached significance (P<.10). A significant reduction in contamination in eggs laid on nest pads was observed (Table 1). There was a significant difference in preference due to nest material. When not given a choice of nest material (Trial 2), broiler breeders did not differ in egg production or feed conversion (Table 2). Egg weight, egg specific gravity, shell weight and percent shell did not differ (data not shown). However, significantly fewer floor eggs were produced in pens supplied with nest pads as the sole nesting material (Table 2). Fertility did not differ between pens supplied exclusively with either nest material, but eggs from pens with nest pads exhibited significantly increased hatch of fertile eggs, and decreased late dead and pipped eggs (Table 2). Hens exhibited a preference for the unpainted nest (Table 3) when given a choice of either an unpainted galvanized metal nest or a
TABLE 1. Effect of nest material on fertility and hatchability of broiler hatching eggs (Trial 1) Nest material Parameter
Nest pad
Fertility, % Hatch of fertile eggs, % Early dead, % Late dead, % Pipped, % Contaminated, % Average eggs laid/nest/
95.1 ± 91.2 ± 3.7 ± 3.2 ± 1.4+ .6± 12.7 ±
.5a' .4a .3a .3a .2a .lb .3b
' Means which possess different differ significantly (P<.05).
Shavings 96.1 90.2 4.3 3.5 1.5 1.2 18.3
± ± ± ± ± + ±
.4a 5a 3a 3a 2a la 3a
superscripts
1 Mean ± SE for 3600 total eggs collected from 8 replicate pens per mean over the entire trial.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
were represented equally. This arrangement was designed to negate positional effects (Hurnik et al, 1973). The number of eggs laid in each individual nest during 29, 33, 37, 4 1 , 45, 49, 5 3, 57, 61, and 65 weeks of age were recorded and collected separately. These eggs were sorted according to nest material on an individual pen basis. Forty-five eggs from each nest material type from each pen were set in a Jamesway 252B incubator (Butler Manufacturing, Ft. Atkinson, WI). Floor eggs were not set. Hatchability was determined, and all unhatched eggs were examined macroscopically to measure fertility, stage of embryonic mortality, and incidence of contamination. Trial 2. Broiler breeders (Hubbard X Hubbard) were grown according to breeder recommendations for fall-hatched birds. The birds were housed in a 2/3-slat breeder house at 20 weeks of age. Birds per pen and details of housing were identical to those of Trial 1. Egg production was initiated at 27 weeks of age. Four pens were equipped with nest pads as the sole nesting material, and four pens were equipped with pine shavings as the sole nesting material. Nest pads were covered with shavings at the initiation of the study. The number of nest-laid eggs and eggs laid on the floor and slats were determined every 4 weeks as in Trial 1. Fertility and hatchability was determined as in Trial 1. Trial 3. An additional two pens from the flock (Trial 2) were equipped with shavings and two pens were equipped with nest pads. Half of the individual nests were painted black and the remaining nests were left as unpainted galvanized metal. The nests were painted on an alternate basis such that all positions were represented equally for all treatments. Eggs laid per nest were determined as in Trial 1. Trial 4. An additional two pens from the flock (Trial 2) were equipped solely with nest pads. Half of the individual nests possessed a flat bottom as normally found, and the bottom of the remaining nests were modified to provide raised sides to form a concave bottom onto which the nest pad was fitted. The nests were again arranged such that all positions were represented equally for nest bottom type. Eggs laid per nest were determined as in Trial 1. Statistical Analysis. Data were subjected to either two-way or one-way analysis of variance with differences among means partitioned by Duncan's new multiple range test where appropriate (SAS Institute, 1982). Percentage
BROILER BREEDER NESTING MATERIALS TABLE 2. Effect of nest material on broiler breeder egg production characteristics* and fertility and hatchability2 (Trial 2) Nest material Parameter
Nest pad 148.01 3.94 6.94 95.46 93.40 4.24 1.54 .49 .56
± 4.22 ± ,14a ± 1.21° ± 1.02 a ± .83a
145.74 3.97 10.01 95.98 91.21
.60a .35b .17b .22a
4.11 2.94 1.39 .63
' Means which possess differ significantly (P<.05).
different
a
± 1.31 ± .05a + 1.23a ± .88a ± .78° .69a .40a ,42a .21a
± ± ± ±
superscripts
1 Mean ± SE for 4 replicate pens for 37 weeks of production. 2 Mean + SE for 1800 total eggs collected from 4 replicate pens per mean over the entire trial.
nest painted flat black. The interaction of nest color and nest material was significant. The shape of the bottom of the nest into which the nest pad was placed also significantly affected the preference. Hens laid more eggs in nests which had concave bottoms than nests which had flat bottoms (Table 4). DISCUSSION Egg laid on nest pads exhibited significantly increased hatchability in Trial 2 and a numerical increase (P<.10) in Trial 1. This was due to
TABLE 3. Effect of nest material and color of nest on nesting characteristics of broiler breeders (Trial 3) Color of nest Nest material
Flat black
Nest pad 16.84 ± . 7 6 ' Shavings 18.37 t .86 X 17.61b
Nest bottom
Eggs laid/nest/week
Flat Concave
17.33 ± . 8 1 b ' 20.90 ± 1.03 a
' Means which possess differ significantly (P<.05).
different
Shavings a
± ± ± ±
TABLE 4. Effect of shape of nest bottom supplied with nest pads on nesting characteristics of broiler breeders (Trial 4)
Unpainted (metal gray) 19.18 ± . 6 4 2 0 . 6 3 ± .88 19.90a
' Means which possess differ significantly (P<.05).
different
X 18.01a 19.50a
superscripts
1 Mean ± SE number of eggs laid per nest per week in each nest of a 12-hole nest box.
superscripts
'Mean ± SE number of eggs laid per nest per week in each nest of a 12-hole nest box.
a significant reduction in late dead and pipped eggs in Trial 2. A similar pattern was not observed in Trial 1 where a significant decrease in contaminated and a numerical decrease (P<.10) in early dead eggs was observed. This was probably due to inherent differences between the two flocks. When given a choice, hens in Trial 1 preferred shavings as a nesting material. However, when allowed to lay in pens equipped with either shavings or nest pads, broiler breeders laid significantly fewer floor eggs with nest pads in the nests. This was not attributable to lower egg production. These effects may be due to reduced broodiness in the pens equipped with nest pads. This would reduce nest setting time and provide more space for laying. This may also explain the differences in embryonic mortality. Similar results have been observed in turkeys (Christensen, personal communication). There has been a common perception among poultry producers that hens do not lay well on artificial nest pads. The data of Trial 1 supports this hypothesis. However, the data of Trial 2 argues against this hypothesis. Therefore, the examination of factors which may promote nesting on nest pads could prove beneficial. Hens preferred unpainted galvanized nests rather than nests painted flat black regardless of the nesting material. Hurnik et al. (1973) found a preference for unpainted galvanized nests when compared to nests painted blue, green, yellow, or red. The general perception that hens prefer dark areas in which to lay has not been supported in other studies as well (Appleby et al, 1984). Wood-Gush and Murphy (1970) also reported that Brown Leghorns exhibited no preference for dark nests unless they had previous experience with such. Most nests which employ nest pads possess a
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
Eggs/hen housed F e e d / d o z e n , kg Floor eggs, % Fertility, % Hatch of fertile eggs, % Early dead, % Late dead, % Pipped, % Contaminated, %
2265
2266
BRAKE
ACKNOWLEDGMENTS
Appreciation is expressed to Monsanto Company, St. Louis, MO for providing the Astroturf® and other financial assistance. The excellent supervision of animal care, data collection for the preference studies, and incubation procedures by James Parsons and statistical assistance of Susan Creech are appreciated.
REFERENCES Appleby, M. C , H. E. McRae, I.J.H. Duncan, and A. Bisazza, 1984. Choice of social conditions by laying hens. Br. Poult. Sci. 25:111-117. Appleby, M. C , H. E. McRae, and B. E. Pietz, 1983. The effect of light on the choice of nests by domestic hens. Appl. Animal Eth. 11:249—254. Brake, J., J. F. Ort, T. A. Carter, and W. R. Campbell, 1984. Effect of the insect growth regulator CGA-72662 (Larvadex®) on broiler breeder production, hatchability, and subsequent chick performance. Poultry Sci. 63:910—916. Daly, D. W., Jr., D. H. Sherwood, and T. B. Morris, 1964. Influence of various nesting materials on number of floor eggs and cracks. Poultry Sci. 43:1311. (Abstr.) Hansen, R. S., G. E. Bearse, and L. R. Berg, 1948. Bird preference for and comparative egg soilage on various nesting materials. Poultry Sci. 27:666. (Abstr.) Hurnik, J. F., F. N. Jerome, B. S. Reinhart, and J. D. Summers, 1973. Colour as a stimulus for the choice of the nesting site by laying hens. Br. Poult. Sci. 1 4 : 1 - 8 . SAS Institute, 1982. SAS User's Guide: Basics. Inst. Cary, NC. Siegel, P. B., and C. E. Howes, 1959. A comparison of various poultry nesting materials. Poultry Sci. 38:1247. (Abstr.) Wood-Gush, D.G.M., 1971. The Behavior of the Domestic Fowl. Heinemann Educational Books, Ltd., London, England. Wood-Gush, D.G.M., and L. B. Murphy, 1970. Some factors affecting the choice of nests by the hen. Br. Poult. Sci. 11:415-417.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
flat bottom. However, it has been reported that the domestic fowl gathers nesting material around her sides when laying and often throws shavings onto her back (Wood-Gush, 1971). The concave nests of Trial 4 were intended to mimic this nest-building effect. The presence of a depression around the hen may account for the preference of concave over flat nest bottoms. These data demonstrate that preferences exhibited by broiler breeder hens when given a choice do not necessarily manifest themselves when a choice is not available. Factors such as nest color and shape also affect nest preference. Nesting remains a complex problem which requires further investigation to successfully automate egg collection in broiler breeders.