- Email: [email protected]
Research Note: Effects of Floor Space Allowance and Group Size on Fear Response of White Leghorns1
Research Note: Effects of Floor Space Allowance and Group Size on Fear Response of White Leghorns1 K. LEE and C. W. MOSS Department of Agriculture, University of Arkansas, Pine Bluff, Arkansas 71601 (Received for publication November 16, 1988)
1989 Poultry Science 68:1024-1026 INTRODUCTION
Recently, a number of behavioral studies on the fear-related response of birds in different group sizes and floor space allowances have been conducted. Hunt and McMillan (1985) and Okpokho et al. (1987) reported that birds in a larger group size were more nervous than birds in a smaller group size, but Cunningham and Ostrander (1982) reported that increasing group size did not affect fear response of the bird. Kujiyat and Craig (1983) reported that increasing group size increased the latency of induced tonic immobility (TI), which was used as a criterion of fearfulness. However, Craig et al. (1986) did not find increased duration of induced TI with decreased floor space among birds in larger group sizes. Most of the experiments in the literature dealing with fear-related response used caged layers. In many of the experiments, group size was altered without holding the floor space allowance per bird constant, which resulted in a combined effect of group size and floor space allowance on fearfulness. Therefore, this study was conducted to determine the separate effect of floor space allowance (Experiments 1 and 3) and that of group size (Experiments 2
'Research supported by CSRS Evans-Allen PL 95-113, Section 1445, ARK01172.
and 3) as well as the combined effect of the two variables (Experiment 3) on fear response of birds housed in floor pens. MATERIALS AND METHODS
General Procedure. Three experiments were conducted with Single Comb White Leghorn pullets for a period of 32 wk each. At 20 wk of age, all birds were weighed, leg banded, and placed into litter-floor pens of two different sizes (4.95 and 6.80 m 2 ). Efforts were made to keep the feeder, waterer, and nest spaces as uniform as possible on a per-bird basis. To determine fear response of the bird, approximately 21 and 15% of the birds in each replicate (pen) of each treatment in Experiments 1 and 3, respectively, were randomly marked at 20 wk of age for a TI test. The percentage figures for Treatments 1 and 2 in Experiment 2 were 22 and 25, respectively. In Experiment 2, 50 and 36 birds per pen for Treatments 1 and 2, respectively, were housed at a floor space allowance of .14 m2/bird. The TI test, as a measure of fearfulness, was conducted at 21 and 52 wk of age for Experiments 1 and 2. In Experiment 3, TI was measured only at 52 wk of age. Latency to the first head movement was also determined when conducting the TI test. Status of the eye
1024
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
ABSTRACT Three experiments were conducted in litter-floor pens to study fear response of White Leghorn layers as affected by floor space allowance and group size. In Experiment 1, 37 birds were housed at a floor space allowance of. 18 or. 13 m2/bird. In Experiment 2,50 or 36 birds were housed at a constant floor space allowance of. 14 m2/bird. The following treatments were used in Experiment 3:51 or 37 birds per pen at. 13 m2/bird; and 37 birds per pen at .19 m2/bir& The study period was from 20 to 52 wk of age in each experiment. Duration of the induced tonic immobility, measured at 52 wk of age, was used as a criterion of fearfulness. Decreasing floor space allowance per bird or increasing group size per pen had no significant effect on fearfulness. Also, the effects of floor space allowance and group size on fear response were not additive under the conditions of this study. (Key words: floor space, group size, floor rearing, fearfulness, tonic immobility)
RESEARCH NOTE
00 ^- ON CN
C\ ON
-H -H -H -H -H -H -H
in en oo 1-1 f »n m V) *0 NO ON 1-" OO *-H ON -H +4 -H -H -H -H 44 c5 ON O ON en -^ v> w> -
S
I NO NO
s
f
oo m
-«t '•t en en
ON
8 ~ CN —
w
oo IX -H
CS
closure (open or closed) was recorded in Experiments 1 and 2 only. The TI test was conducted by placing the bird on her back with the head hanging over the edge of a U-shaped, bare wood "cradle" with a base as shown by Craig et al. (1984). Duration of the TI was recorded as the period between the time the bird became immobile and when it stood up. Latency to the first head movement was recorded as the period between the time the bird became immobile and when the first movement of its head was made. The TI was induced according to the method described by Craig et al. (1984). In order to maintain the original floor space allowance per bird and keep the number of birds per pen constant, all dead birds were immediately replaced with birds from the same hatch. >Vhen birds marked for the TI test died, replacement birds were not subjected to the TI test. Replacement birds had been subjected to the same feeding and management conditions as those birds in experimental groups. All data, except for the eye closure, were analyzed using either the Student's t test (Experiments 1 and 2) or a one-way ANOVA (Experiment 3) by procedures in the Statistical Analysis System (SAS, 1985). Standard errors of the means were calculated using the PROC MEANS procedure of SAS. Eye closure data were analyzed by the chi-square test (Gill, 1978). Data on TI and latency to the first head movement were transformed to logarithm prior to analyses. Experiment 1. There were four replicates in each of the two treatments. Two hundred and ninety-six pullets were randomly placed into four large (Treatment 1) and four small (Treatment 2) floor pens. The number of birds in each pen, regardless of the size of pen, was 37. Floor space allowances per bird were .18 and .13 m^ for birds in Treatments 1 and 2, respectively. Experiment 2. There were three replicates in each of the two treatments. Two hundred and fifty-eight pullets were distributed into six pens of two different sizes in such a way that each of the three large pens for Treatment 1 contained 50 birds, and each of the three small pens for Treatment 2 contained 36 birds. Floor space allowance was .14 m^/bird in each treatment. Experiment 3. There were three replicates in each of the three treatments. In Treatment 1, there were 37 birds in a small pen at .13 m 2
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
-H -H -H -H
1025
1026
LEE AND MOSS TABLE 2. Correlation coefficients of fear-related criteria measured at 52 weeks of age and floor space allowance and group size Experiment
Variables correlated
1 (n = 64)
2 (n = 58)
3 (n = 55)
.04 .25
-.03 -.13 .16 .15
2
Floor space/bird (m ) and duration of induced tonic immobility (logio s) -.18 Floor space/bird (m 2 ) and latency to first head movement (logio s) -.08 Group size/pen (n) and duration of induced tonic immobility (logio s) s Group size/pen (n) and latency to first head movement (logio ) 'None of the correlation coefficients were significant (P>.05).
allowance or group size in a floor pen had no significant effect on fearfulness of the bird and that the effects of floor space allowance and group size on fear response were not additive under the conditions of this study.
RESULTS AND DISCUSSION
Neither floor space allowance (Experiment 1) nor group size (Experiment 2) significantly influenced fear response of the bird as measured by the duration of induced TI at 52 wk of age (Table 1). Also, decreasing floor space allowance with increasing group size (Experiment 3, Treatments 2 vs. 3) had no significant effect on fear response. This is in agreement with the result obtained by Craig et al. (1986). The study by Craig et al„ however, was conducted with caged layers. Latency to the first head movement was not significantly affected by floor space allowance, group size, or combination of the two. Correlation coefficient analyses (Table 2) also showed that neither the duration of induced TI nor the latency to the first head movement was significantly correlated with floor space allowance or group size. Most of the test birds in Experiments 1 and 2 closed their eyes (momentary eye closure included) during the test periods. The present study revealed that floor space
REFERENCES Craig, J. V„ S. K. Kujiyat, and A. D. Dayton, 1984. Tonic immobility responses of White Leghorn hens affected by induction techniques and genetic stock differences. Poultry Sci. 63:1-10. Craig, J. V., J. Vargas, and G. A. Milliken, 1986. Fearful and associated responses of White Leghorn hens: Effects of cage environments and genetic stocks. Poultry Sci. 65:2199-2207. Cunningham, D. L., and C. E. Ostrander, 1982. The effects of strain and cage shape and density on performance and fearfulness of White Leghorn layers. Poultry Sci. 61:239-243. Gill, J. L., 1978. Design and Analysis of Experiments in the Animal and Medical Sciences. Volume 1. Iowa State Univ. Press, Ames, IA. Hunt, E. C , and I. McMillan, 1985. The effect of bird density and space on the parameters of egg production and profitability. Poultry Sci. 64(Suppl. 1):24. (Abstr.) Kujiyat, S. K„ and J. V. Craig, 1983. Duration of tonic immobility affected by housing environment in White Leghorn hens. Poultry Sci. 62:2280-2282. Okpokho, N. A., J. V. Craig, and G. A. Milliken, 1987. Density and group size effects on caged hens of two genetic stocks differing in escape and avoidance behavior. Poultry Sci. 66:1905-1910. SAS, 1985. SAS/STAT™ Guide for Personal Computers. Version 6 ed. SAS Inst. Inc., Cary, NC.
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
floor space/bird. In Treatment 2, there were 51 birds in a large pen at .13 m^/bird. In Treatment 3, there were 37 birds in a large pen at .19 m2/bird.
1989 Poultry Science 68:1024-1026 INTRODUCTION
Recently, a number of behavioral studies on the fear-related response of birds in different group sizes and floor space allowances have been conducted. Hunt and McMillan (1985) and Okpokho et al. (1987) reported that birds in a larger group size were more nervous than birds in a smaller group size, but Cunningham and Ostrander (1982) reported that increasing group size did not affect fear response of the bird. Kujiyat and Craig (1983) reported that increasing group size increased the latency of induced tonic immobility (TI), which was used as a criterion of fearfulness. However, Craig et al. (1986) did not find increased duration of induced TI with decreased floor space among birds in larger group sizes. Most of the experiments in the literature dealing with fear-related response used caged layers. In many of the experiments, group size was altered without holding the floor space allowance per bird constant, which resulted in a combined effect of group size and floor space allowance on fearfulness. Therefore, this study was conducted to determine the separate effect of floor space allowance (Experiments 1 and 3) and that of group size (Experiments 2
'Research supported by CSRS Evans-Allen PL 95-113, Section 1445, ARK01172.
and 3) as well as the combined effect of the two variables (Experiment 3) on fear response of birds housed in floor pens. MATERIALS AND METHODS
General Procedure. Three experiments were conducted with Single Comb White Leghorn pullets for a period of 32 wk each. At 20 wk of age, all birds were weighed, leg banded, and placed into litter-floor pens of two different sizes (4.95 and 6.80 m 2 ). Efforts were made to keep the feeder, waterer, and nest spaces as uniform as possible on a per-bird basis. To determine fear response of the bird, approximately 21 and 15% of the birds in each replicate (pen) of each treatment in Experiments 1 and 3, respectively, were randomly marked at 20 wk of age for a TI test. The percentage figures for Treatments 1 and 2 in Experiment 2 were 22 and 25, respectively. In Experiment 2, 50 and 36 birds per pen for Treatments 1 and 2, respectively, were housed at a floor space allowance of .14 m2/bird. The TI test, as a measure of fearfulness, was conducted at 21 and 52 wk of age for Experiments 1 and 2. In Experiment 3, TI was measured only at 52 wk of age. Latency to the first head movement was also determined when conducting the TI test. Status of the eye
1024
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
ABSTRACT Three experiments were conducted in litter-floor pens to study fear response of White Leghorn layers as affected by floor space allowance and group size. In Experiment 1, 37 birds were housed at a floor space allowance of. 18 or. 13 m2/bird. In Experiment 2,50 or 36 birds were housed at a constant floor space allowance of. 14 m2/bird. The following treatments were used in Experiment 3:51 or 37 birds per pen at. 13 m2/bird; and 37 birds per pen at .19 m2/bir& The study period was from 20 to 52 wk of age in each experiment. Duration of the induced tonic immobility, measured at 52 wk of age, was used as a criterion of fearfulness. Decreasing floor space allowance per bird or increasing group size per pen had no significant effect on fearfulness. Also, the effects of floor space allowance and group size on fear response were not additive under the conditions of this study. (Key words: floor space, group size, floor rearing, fearfulness, tonic immobility)
RESEARCH NOTE
00 ^- ON CN
C\ ON
-H -H -H -H -H -H -H
in en oo 1-1 f »n m V) *0 NO ON 1-" OO *-H ON -H +4 -H -H -H -H 44
S
I NO NO
s
f
oo m
-«t '•t en en
ON
8 ~ CN —
w
oo IX -H
CS
closure (open or closed) was recorded in Experiments 1 and 2 only. The TI test was conducted by placing the bird on her back with the head hanging over the edge of a U-shaped, bare wood "cradle" with a base as shown by Craig et al. (1984). Duration of the TI was recorded as the period between the time the bird became immobile and when it stood up. Latency to the first head movement was recorded as the period between the time the bird became immobile and when the first movement of its head was made. The TI was induced according to the method described by Craig et al. (1984). In order to maintain the original floor space allowance per bird and keep the number of birds per pen constant, all dead birds were immediately replaced with birds from the same hatch. >Vhen birds marked for the TI test died, replacement birds were not subjected to the TI test. Replacement birds had been subjected to the same feeding and management conditions as those birds in experimental groups. All data, except for the eye closure, were analyzed using either the Student's t test (Experiments 1 and 2) or a one-way ANOVA (Experiment 3) by procedures in the Statistical Analysis System (SAS, 1985). Standard errors of the means were calculated using the PROC MEANS procedure of SAS. Eye closure data were analyzed by the chi-square test (Gill, 1978). Data on TI and latency to the first head movement were transformed to logarithm prior to analyses. Experiment 1. There were four replicates in each of the two treatments. Two hundred and ninety-six pullets were randomly placed into four large (Treatment 1) and four small (Treatment 2) floor pens. The number of birds in each pen, regardless of the size of pen, was 37. Floor space allowances per bird were .18 and .13 m^ for birds in Treatments 1 and 2, respectively. Experiment 2. There were three replicates in each of the two treatments. Two hundred and fifty-eight pullets were distributed into six pens of two different sizes in such a way that each of the three large pens for Treatment 1 contained 50 birds, and each of the three small pens for Treatment 2 contained 36 birds. Floor space allowance was .14 m^/bird in each treatment. Experiment 3. There were three replicates in each of the three treatments. In Treatment 1, there were 37 birds in a small pen at .13 m 2
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
-H -H -H -H
1025
1026
LEE AND MOSS TABLE 2. Correlation coefficients of fear-related criteria measured at 52 weeks of age and floor space allowance and group size Experiment
Variables correlated
1 (n = 64)
2 (n = 58)
3 (n = 55)
.04 .25
-.03 -.13 .16 .15
2
Floor space/bird (m ) and duration of induced tonic immobility (logio s) -.18 Floor space/bird (m 2 ) and latency to first head movement (logio s) -.08 Group size/pen (n) and duration of induced tonic immobility (logio s) s Group size/pen (n) and latency to first head movement (logio ) 'None of the correlation coefficients were significant (P>.05).
allowance or group size in a floor pen had no significant effect on fearfulness of the bird and that the effects of floor space allowance and group size on fear response were not additive under the conditions of this study.
RESULTS AND DISCUSSION
Neither floor space allowance (Experiment 1) nor group size (Experiment 2) significantly influenced fear response of the bird as measured by the duration of induced TI at 52 wk of age (Table 1). Also, decreasing floor space allowance with increasing group size (Experiment 3, Treatments 2 vs. 3) had no significant effect on fear response. This is in agreement with the result obtained by Craig et al. (1986). The study by Craig et al„ however, was conducted with caged layers. Latency to the first head movement was not significantly affected by floor space allowance, group size, or combination of the two. Correlation coefficient analyses (Table 2) also showed that neither the duration of induced TI nor the latency to the first head movement was significantly correlated with floor space allowance or group size. Most of the test birds in Experiments 1 and 2 closed their eyes (momentary eye closure included) during the test periods. The present study revealed that floor space
REFERENCES Craig, J. V„ S. K. Kujiyat, and A. D. Dayton, 1984. Tonic immobility responses of White Leghorn hens affected by induction techniques and genetic stock differences. Poultry Sci. 63:1-10. Craig, J. V., J. Vargas, and G. A. Milliken, 1986. Fearful and associated responses of White Leghorn hens: Effects of cage environments and genetic stocks. Poultry Sci. 65:2199-2207. Cunningham, D. L., and C. E. Ostrander, 1982. The effects of strain and cage shape and density on performance and fearfulness of White Leghorn layers. Poultry Sci. 61:239-243. Gill, J. L., 1978. Design and Analysis of Experiments in the Animal and Medical Sciences. Volume 1. Iowa State Univ. Press, Ames, IA. Hunt, E. C , and I. McMillan, 1985. The effect of bird density and space on the parameters of egg production and profitability. Poultry Sci. 64(Suppl. 1):24. (Abstr.) Kujiyat, S. K„ and J. V. Craig, 1983. Duration of tonic immobility affected by housing environment in White Leghorn hens. Poultry Sci. 62:2280-2282. Okpokho, N. A., J. V. Craig, and G. A. Milliken, 1987. Density and group size effects on caged hens of two genetic stocks differing in escape and avoidance behavior. Poultry Sci. 66:1905-1910. SAS, 1985. SAS/STAT™ Guide for Personal Computers. Version 6 ed. SAS Inst. Inc., Cary, NC.
Downloaded from http://ps.oxfordjournals.org/ at GWU on April 28, 2015
floor space/bird. In Treatment 2, there were 51 birds in a large pen at .13 m^/bird. In Treatment 3, there were 37 birds in a large pen at .19 m2/bird.