EDUCATION AND PRODUCTION

EDUCATION AND PRODUCTION Effects of Floor Versus Cage Rearing and Feeder Space on Growth, Long Bone Development, and Duration of Tonic Immobility in Single Comb White Leghorn Pullets 1 ' 2 K. E. ANDERSON 3 Department of Poultry Science, North Carolina State University, Box 7608, Raleigh, North Carolina 27695-7608 A. W. ADAMS Department of Animal Sciences and Industry, Kansas State University, Manhattan, Kansas 66506 ABSTRACT The effects of feeder space on growth of commercial layer pullets reared in cages or floor pens were examined by allocating 1-d-old chicks to either cages (14 chicks) or floor (119 chicks). Feeder spaces were 5.4,4.0, and 2.7 cm per pullet and were held constant throughout the growing period, resulting in a 2 x 3 factorial arrangement. Measurements of pullet body weight, feed consumption, skeletal development, and fearfulness were taken through the rearing period to 18 wk. Pullets allowed 5.4 cm of feeder space were heavier (P <.001) (1,329 g at 18 wk of age) than birds allowed either 4.0 or 2.7 cm of feeder space (1,289 and 1,272 g, respectively). Floor-reared pullets weighed significantly more at 12, 16, and 18 wk of age than cage-reared pullets. Feed consumption was not affected by the feeder space, but the floor-reared birds consumed more (P <.001) feed than those in cages (61.2 vs 52.8 g per pullet per d). Mortality, skeletal development, and bone strength were not affected by either feeder space or floor vs cage rearing. Floor-reared pullets had longer (P <.05) duration of tonic immobility (TI) than those reared in cages (519.7 and 471.4 s, respectively, as measured at 18 wk). Feeder space per pullet had no effect on the duration of TI of the pullets. Cage and floor rearing environments are comparable for rearing pullets provided feeder space is not restricted to such an extent as to inhibit BW. (Key words: pullet, flooring, feeder space, bone strength, tonic immobility) INTRODUCTION The egg industry has progressed from floor pens to cages for growing replace- Received for publication November 22, 1993. Accepted for publication March 3, 1994. 1 The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service or Kansas Agricultural Experiment Station of the product named or criticism of similar ones not mentioned. Contribution Number 94-203-J, from the Kansas Agricultural Experiment Station, Manhattan, KS 66506. 3 To whom correspondence should be addressed. 958 1994 Poultry Science 73:958-964 ment layer pullets. The differences between the pullets' growth in these two environments were examined by Rowland and Harms (1970) and Deaton et ah (1985). These studies evaluated development of skeletal and digestive organs and found that floor-reared pullets had stronger tibias, greater percentage ash, and heavier digestive organs than cage-reared pullets. These observations were attributed to the difference in activity levels and movement capabilities and the fact that the birds in floor pens had access to the litter or waste as a mineral and fiber source. Stockland and Blaylock (1974) and Jin and Craig

REARING ENVIRONMENT EFFECTS ON LEGHORN PULLETS 959 (1988) determined that cage-reared pullets were heavier (P <.001) than floor-reared birds at 5, 11, and 19 wk of age. Broilers (Reece et al, 1971), layer pullets (Deaton et al, 1985), and turkeys (Anderson et al, 1979) were significantly heavier at market age when raised in cages. The weight difference was attributed to the lower activity and smaller floor space for the cage-reared birds (Anderson et al, 1979). In the United States, brooding and rearing of commercial layer pullets in cages is the most prevalent method in the poultry industry because of the reduced housing and equipment costs per pullet. However, with the use of cages, the effects on growth and skeletal development of the pullets must be monitored to counteract possible negative environmental factors (Anderson and Adams, 1992). Highdensity rearing environments for replacement layer pullets were shown by Anderson and Adams (1992) to result in a significant reduction in body weight at 18 wk of age. The weight depression was found to be related to feeder space rather than density alone. In addition, Bell (1969) and Davami et al. (1987) showed significantly reduced pullet body weights at 18 wk of age when feeder space was reduced. Duration of tonic immobility (TI) has been shown to be a good criterion for measuring the fearfulness response in birds. Okpokho and Craig (1987) found that neither cage nor floor rearing influenced the fearfulness of 23-wk-old pullets as measured by TI. Kujiyat et al. (1983) found no differences between the TI of hens at 47 and 55 wk of age for 1- and 5-hen cages or 15-hen floor pens. However, hens from 17-hen colony cages had significantly longer duration of TI, suggesting that the population within the enclosure contributes to TI duration. The objectives of this study were to elucidate the effects of cage vs floor rearing and rearing feeder space on growth, feed consumption, skeletal development, and fearfulness of pullets. 4 Instron Corp., Canton, MA 02021. MATERIALS AND METHODS A commercial strain (Babcock B-300) of White Leghorn chicks was purchased from a local hatchery in the fall. The chicks were wing-banded and assigned randomly to either litter-covered floor pens (119 chicks per pen) or double-deck, brooder or grower cages (14 chicks per cage). Both pens and cages were located in the same curtain-sided, naturally ventilated, brooding-rearing house. The floor areas per bird (density) were 744 cm 2 per pullet in the floor pens and 304 cm 2 per pullet in cages. These densities were selected to represent those used in commercial facilities, but they exceeded recommended densities (Consortium, 1988; Anderson and Adams, 1992). Feeder space was provided by tube feeders in the floor pens and feed troughs in the cages. Total feeder space was held at 2.7, 4.0, or 5.4 cm per bird in cages and floor pens by constructing covers for the trough and tube feeders. Surplus chicks were distributed among cages and floor pens with environments similar to the treatments. Mortalities were recorded daily for cages and floor pens, and dead birds were replaced by birds from similar environments in order to maintain populations and densities. Chicks were provided ad libitum access to the standard Kansas State University step-down protein dietary regimen consisting of a 21% CP, 2,823 kcal ME/kg starter diet fed from 0 through 6 wk, a 18% CP, 2,864 kcal ME/kg grower diet fed from 7 to 12 wk, and a 16% CP, 3,000 kcal ME/kg developer diet fed from 13 through 18 wk. Residual feed weighback and pullet body weights were determined every 4 wk and at the end of the rearing period. At 18 wk of age, eight pullets from each treatment combination were selected randomly by wing-band number and killed by cervical dislocation. The right tibia was excised for further analysis. The tibias were handled according to the procedure outlined by Crenshaw et al. (1981). The bones were cleaned of excess tissues, and the peak breaking force was determined using an Instron Model 1122. 4 The bones were supported by two fulcrum points (27 mm apart), and force was applied midshaft at a constant rate of (300 mm/min) to all bones. The peak force was recorded automatically by a 500-kg electronic load

960 ANDERSON AND ADAMS cell set for reading at 10% of capacity. After breaking, the bones were dried for 24 h at 100 C and extracted with dimethylether for 36 h in a Soxhlet extractor. The bones were ashed at 600 C for 12 h, until reduced to mineral form. After cooling, bone ash was measured by weight (Association of Official Analytical Chemists, 1984). The effects of the floor type and feeder space on fearfulness levels of the pullets were assessed using the TI technique outlined by Craig et al. (1984). The latency until righting time (i.e., stand up) from induced TI at 18 wk of age was used as the indicator of fearfulness. The procedure utilized a Y-shaped cradle with a base covered with a piece of black velvet. The pullet was placed in the cradle on her back with her head hanging over the edge. The pullet was restrained for 15-s period, then the observer's hand was removed. If the pullet remained immobile for 10-s, TI was considered induced and the duration time of TI was recorded. Testing was completed on a random sample of 16 pullets from each environment prior to movement to the laying house. A randomized block design 2x3 factorial arrangement of floor or cage rearing and feeder space was used. Data were analyzed with the floor pen or the cage as the experimental unit, using the General Linear Models (GLM) procedure of SAS software (SAS Institute, 1985) to allow for unequal sample sizes. Mortality percentages were transformed to arc sine percentage prior to analysis. The righting times were recorded in seconds and, before analysis, were converted to log 10 seconds. Means detected to be significantly different by GLM were separated using Duncan's (1955) multiple range test (SAS Institute, 1985). RESULTS AND DISCUSSION In this experiment, no significant interactions between the main effects of floor or cage rearing and feeder space per bird occurred. Body weights were heavier for floor-reared pullets throughout the rearing period, reaching significance at 12 wk of age and persisting through the growth period to 18 wk of age (Table 1). These results agree with the work done by Rowland and Harms (1970), who also n 4) 1 a. g i S.a 4! I w +i 15 u o I -H +1 o cs CS 00 oo i< -H +1 +1 -H o\ < in m +1 +1 ^O CO 32 -H +1 Si +1 -H S3 in vo ^ 1 I f-h -H -H cs oo vo in is'

REARING ENVIRONMENT EFFECTS ON LEGHORN PULLETS 961 found that pullets reared in floor pens were heavier. Bond et al. (1989) found similar results in floor-reared birds, which were heavier than birds reared in cages. They related the heavier weights to temperature differences in the rearing environments. In their experiment, the environmental temperatures were lower for the floor-reared birds, which stimulated increased feed consumption. During the season of the year in which our trial was begun, the ambient temperatures were approximately 5.5 C lower for the floorreared birds than for the cage-reared pullets due to the air stratification in the room. This resulted in similar increases in feed consumption with significantly higher feed intake overall for the floor- vs cage-reared birds of (61.2 and 52.8 g per bird per d). Mortality was not different for floor- and cage-reared pullets. The heavier body weights did not affect long bone development in the pullets (Table 2). This disagrees with the findings of Bond et al. (1989), who determined that floor-reared birds had significantly longer leg bones than cage-reared birds. The breaking strength and percentage ash of the tibias from the floor- or cage-reared pullets were not different. This is contrary to results of Rowland et al. (1968, 1971), Rowland and Harms (1970), and Reece et al. (1971). The differences between those studies and our study may have been the dietary levels of Ca and P. The four previous studies used diets with P levels between.6 and.7% compared with the.73% P levels used in our study. Also, floor-reared birds, having access to the waste in litter, could have consumed additional P over cage-reared birds. Anderson et al. (1979) showed that, in turkeys, bone mineralization increased and the percentage of bone breakage frequency decreased as P levels increased to.71% of the diet. The P levels in excess of.73% in the rearing diets in our study allowed adequate P intake for floor- and cage-reared birds. Mineralization was not affected by either floor or cage rearing environments in this experiment, similar to the results reported by Bond et al. (1989). Floor-reared pullets took significantly longer times to recover from induced Tl (righting time) at 18 wk of age than cagereared pullets (Table 2). This is contrary to the findings of Jones and Faure (1981), who reported that caged hens had significantly longer TI times than hens kept on the floor. Okpokho and Craig (1987) reported no differences in TI for 23-wk-old pullets raised in cages or floor pens. The confounding of population and density may have contributed to the differences shown herein; however, the differences in density in the floor pens and feeder spaces may have contributed to the greater TI duration in the floor-reared pullets in this study. Kujiyat et al. (1983) found that 47- and 55-wk-old hens in colony cages had significantly longer TI duration than hens in floor pens and attributed to increased fearfulness. The floor-reared pullets in our study had the ability to move away from the caretakers and did not have the same interaction that occurred with the caged pullets. In addition, the density in the floor pens was only 33% of that used by Kujiyat et al. (1983). This could have potentiated longer righting times in the pullets from the floor environment in our study. TABLE 2. Effect (x ± SE) of floor vs cage rearing on bone length, tibia strength, tibia ash, tonic immobility, and small intestine weight in Single Comb White Leghorn pullets Rearing system Floor Cage Femur length length (mm) 84.9 ±.65 119.2 ±.49 84.9 ±.63 120.4 ±.89 breaking strength (kg/cm*) 25.3 ± 4.05 25.5 ± 3.81 ash (%) 55.2 ± 1.38 51.9 ± 2.15 Tonic immobility 1 (s) 519.7 ± 53.07* 471.8 ± 75.53 Small intestine (g) 20.7 ±.71* 18.3 ±.66 iobserved at 18 wk of age. Values indicate seconds required for birds to right itself (stand up). *P <.05 between rearing systems.

962 ANDERSON AND ADAMS Pullets reared in floor pens on litter had significantly (P <.05) heavier small intestine weights than those reared in cages (Table 2). This could be attributed to the fact that pullets in the floor pens consumed litter material, resulting in increased fiber intake and increased intestinal length (Deaton et al, 1985). Mortality was not affected by the feeder space allocations. Feeder space had no effect on body weight until the pullets reached 12 wk of age (Table 3). Then pullets reared on 2.7 cm of feeder space per bird showed significant reductions in body weight compared with those reared at 4.0 or 5.4 cm per pullet (23 and 25 g, respectively). The pullets reared on feeder space of 2.7 cm per pullet remained lighter at 16 wk of age, and, by 18 wk, birds in both the 2.7- and 4.0-cm treatment groups were significantly lighter than birds in the 5.4-cm group. Lighter pullet weights found here correspond with results reported by Bell (1969) and Davami et al. (1987). However, the birds used by those researchers and hens used by Robinson (1979) showed depressed feed intake as feeder space was reduced. The pullets in the present study did not have depressed feed consumption, precluding reduced feed intake as a possible cause of body weight differences. The body weight differences may have been related to the increased activity levels of the pullets in cages with the restricted feeder space. Though not measured on an index, we observed that movement among the pullets with restricted feeder space was markedly higher, resulting in increased consumption of energy and use of nutrients consumed to support the increased activity instead of growth. This was supported by the increased (P >.05) latency of TI (tearfulness) shown by the pullets reared with feeder space of 2.7 and 4.0 cm per pullet vs those reared with 5.4 cm per pullet (Table 4). Bone length, breaking strength, bone ash, and small intestine weight were not affected by feeder space (Table 4). g o Ml S ft f I a W CA +1 UH! U vd eo od +1 +1 +1 00 ON "3* in co <-H CN CM CD in K ON +1 +1 +1 ^- in N oo H +1 +1 oo d\ ( 383 H -H -H firini H -H -H!2SS +1 +1 -H - t< -^ in 3 +1 +1 +1 5" vo er> m ' ON ON in w The results from this study indicated that feeder space is one of the limiting factors in any confinement pullet-rearing environment, in addition to density, waterer space, and population. Brooder- XI 6 IN o * -s- H»* in

REARING ENVIRONMENT EFFECTS ON LEGHORN PULLETS 963 TABLE 4. Effect (x ± SE) of feeder space on bone length, tibia strength, tibia ash, tonic immobility, and small intestine weight in Single Comb White Leghorn pullets Feeder Femur breaking Tonic Small space length length strength ash immobility 1 intestine (cm) (mm) (kg/cm*) (%) (s) (g) 2.7 85.4 ±.97 118.8 ±.87 26.6 ± 4.61 53.9 ± 3.22 507.1 ± 74.05 19.86 ±.85 4.0 85.3 ±.74 120.5 ±.73 24.1 ± 5.16 50.7 ± 1.22 528.3 ± 92.45 18.85 ±.91 5A 84.1 ±.57 120.0 ± 1.03 25.5 ± 4.78 56.0 ± 1.68 451.7 ± 72.84 19.83 ±.94 1 Observed at 18 wk of age. Values indicate seconds required for birds to right itself (stand up). grower cages used in the growing of pullets for the layer industry should not be overpopulated, because of the adverse pressure put on the bird to access the feed trough. The ability of pullets to reach their optimum growth may be restricted if feeder space falls below 4.0 cm per bird. If carried to the extreme, such restriction could affect flock uniformity and reduce subsequent production. The duration of TI was higher (P <.05) than in floor-reared pullets than in cagereared pullets. As a measure of fearfulness in pullets, TI indicated that cage-rearing is an acceptable alternative to floor-rearing, as long as feeder space is adequate. Even though body weights at 18 wk were lower for cage-reared pullets, frame size and skeletal strength were not affected. Therefore, they should be ready to move to the production facility at that age. REFERENCES Association of Official Analytical Chemists, 1984. Official Methods of Analysis. 14th ed. Association of Official Analytical Chemists, Washington, DC. Anderson, K. E., and A. W. Adams, 1992. Effects of rearing density and feeder and waterer spaces on the productivity and fearful behavior of layers. Poultry Sci. 71:53-58. Anderson, J. O., R. E. Warnick, and N. Nakhata, 1979. Effect of cage and floor rearing; dietary calcium, phosphorus, fluoride, and energy levels; and temperature on growing turkey performance, the incidence of broken bones and bone weight, and ash. Poultry Sci. 58:1175-1182. Bell, D., 1969. Crowding in cage rearing affects pullet weights. Poult. Trib. (Jan.):18, 19, 28. Bond, P. L., T. W. Sullivan, J. H. Douglas, L. Robeson, and J. Baier, 1989. Influence of age and sex on bone development of broilers. Poultry Sci. 68(Suppl. l):15.(abstr.) Consortium, 1988. Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. Consortium for Developing a Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. Association Headquarters, Champaign, IL 61820. 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. Crenshaw, T. D., E. R Peo, Jr., A. J. Lewis, B. D. Moser, and D. Olsen, 1981. Influence of age, sex and calcium and phosphorus levels on the mechanical properties of various bones in swine. J. Anim. Sci. 52:1319-1329. Davami, A., M. J. Wineland, W. T. Jones, R. L. Ilardi, and R A. Peterson, 1987. Effects of population size, floor space and feeder space upon productive performance, external appearance and plasma corticosterone concentration of laying hens. Poultry Sci. 66:251-557. Deaton, J. W., S. L. Branton, B. D. Lott, and J. D. Brake, 1985. Noted difference in the digestive system in cage and floor-reared commercial egg-type pullets. Poultry Sci. 64:1035-1037. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1-42. Jin, L., and J. V. Craig, 1988. Some effects of cage and floor rearing on commercial white leghorn pullets during growth and the first year of egg production. Poultry Sci. 67:1400-1406. Jones, R. B., and J. M. Faure, 1981. Tonic immobility ("righting time") in laying hens housed in cages and pens. Appl. Anim. Ethol. 7:369-372. Kujiyat, S. K., J. V. Craig, and A. D. Dayton, 1983. Duration of tonic immobility affected by housing environment in white leghorn hens. Poultry Sci. 62:2280-2282. Okpokho, N. A., and J. V. Craig, 1987. Fear-related behavior of hens in cages: Effects of rearing environment, age, and habituation. Poultry Sci. 66:376-377. Reece, F. N., J. W. Deaton, J. D. May, and K. N. May, 1971. Cage versus floor rearing of broiler chickens. Poultry Sci. 50:1786-1790. Robinson, D., 1979. Effects of cage shape, colony size, floor area and cannibalism preventatives on laying performance. Br. Poult. Sci. 20:345-356. Rowland, L. O., Jr., B. L. Damron, E. Ross, and R. H.

964 ANDERSON AND ADAMS Harms, 1971. Comparisons of bone characteristics between floor and battery grown broilers. Poultry Sci. 50:1121-1124. Rowland, L. O., Jr., and R. H. Harms, 1970. The effect of wire pens and cages on bone characteristics of laying hens. Poultry Sci. 49:1223-1225. Rowland, L. O, Jr., H. R. Wilson, J. L. Fry, and R. H. Harms, 1968. A comparison of bone strength of caged and floor layers and roosters. Poultry Sci. 47:2013-2015. SAS Institute, 1985. SAS User's Guide: StatisHcs. Version 5 Edition. SAS Institute Inc., Cary, NC. Stockland, W. L., and L. G. Blaylock, 1974. The influence of ration protein level on the performance of floor reared and cage reared replacement pullets. Poultry Sci. 53:790-800.