Beak Trimming Effects on Beak Length and Feed Usage for Growth and Egg Production1'2 J. V. CRAIG,3'4 J. A. CRAIG,5 and G. A. MILLIKEN6 Departments of Animal Sciences and Industry and Statistics, Kansas State University, Manhattan, Kansas 66506
1992 Poultry Science 71:1830-1841
ticosteroid levels were lower and adrenal and thyroid gland weights were lighter for Neurophysiological and behavioral ob- beak-trimmed hens than for hens with servations provide indirect evidence that intact beaks, thereby suggesting that those beak trimming of pullets causes pain, with trimmed beaks were under less which apparently persists for weeks or stress. The argument in favor of beak even months (Breward and Gentle, 1985; trirruning has been that, if properly done, Duncan et ah, 1989; Craig and Lee, 1990; beak trirnming provides insurance against Gentle et al, 1990; Lee and Craig, 1990, feather and cannibalistic pecking, which 1991). Therefore, it is surprising that are otherwise likely to occur among hens Eskland (1981) found that plasma cor- kept for egg production (Consortium, 1988). Recent studies suggest that at least one stock of White Leghorns does not require Received for publication May 11, 1992. beak trimming (Craig and Lee, 1990; Accepted for publication July 20, 1992. Contribution Number 92-565-J, Kansas Agricul- Craig, 1992b), and Gentle (1986) reported tural Experiment Station, Manhattan, Kansas 66506. that a commercial breeder of brown egg 2 This investigation is part of the Kansas contribu- layers recommended that customers tion to the NC-168 Regional Poultry Project. should not beak trim birds of their stock. department of Animal Sciences and Industry. 4 To whom correspondence should be addressed. Other recent studies report evidence that kin selection among intact hens of stocks sVolunteer. susceptible to heavy losses from cannibaldepartment of Statistics. INTRODUCTION
1830
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
ABSTRACT Two experiments were conducted to compare beak treatment effects on pullets of three genetic stocks. Within each stock, equal numbers were assigned to three treatments: no beak trimming (IN), beak trimming once (IX), and beak trimming twice (2X). Beak treatment, genetic stock, and age effects along with interactions among main effects were examined for productionassociated traits during rearing and brief periods of early egg production. Beaks of IX and 2X pullets remained shorter than those of IN pullets through final measurements at 36 and 32 wk of age in Experiments 1 and 2, respectively. However, differences in beak length decreased as age increased. Upper beaks of 2X pullets remained shorter than those of IX pullets, but lower beaks of IX and 2X pullets did not differ by 20 wk in Experiment 2. Weight gains, feed usage, and efficiency of growth were affected by beak treatments. Beak trimming reduced gains, feed eaten, feed wasted, and total feed used, and 2X pullets used their feed more efficiently for weight gain and egg production. A general decrease occurred in differences among beak treatments for weight gains, feed eaten, feed wasted, and efficiency of gains with increasing age during rearing. Nevertheless, significant differences in feed consumed, feed wasted, and efficiency of feed used for egg production indicated an economic advantage in favor of beak trimming. (Key words: beak trimming, genetic stocks, feed usage, growth, egg production)
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
THy-Line International, Dallas Center, IA 50063. H&N International, Redmond, WA 98052.
8
MATERIALS AND METHODS Three genetic stocks were used: HyLine® W-36 (W36),7 Hy-Line® W-77 (W77),7 and Strain N. The W36 and W77 hatching eggs were obtained directly from the breeder. The N hatching eggs were produced at the authors' station by mating together randomly chosen males and females from H&N Nick Chick®8 foundation stock following two generations of relaxed selection. Ages of W36 and W77 parental stocks were unknown, but hatching eggs were obtained from different flocks and it is likely that hatchery flock hens of the three stocks differed in age as well as other unidentified variables. Indirect evidence (size of hatching eggs) suggests that older hens of W36 than of W77 were used and that N hens were the youngest of the three stocks. Approximately 2,100 eggs of each stock were set simultaneously in the same incubator. At hatching, chicks were wingbanded, sexed, cockerels were disposed of humanely, and pullets were vaccinated for Marek's disease. Subsequent vaccinations and rations used were the same as those indicated by Okpokho et al. (1987). Feed was always provided in the form of mash. Rearing Period Experiment 1. Experimental pullets were placed in the second through fourth decks of four, six-deck, battery brooders having two cages on each deck. The top decks contained excess chicks. Within each battery brooder, 15 experimental chicks of the same stock occupied each of the two cages of a single, randomly selected deck. Thus, 30 chicks of each stock were used in each of four battery brooders so that a total of 360 chicks was involved. Compartments were 68.6 cm wide by 99.1 cm long, including a heated brooding area of 30.5 by 68.6 cm. A. few pullets that died or lost their wing bands during the first 9 days were replaced by pullets of the same stock from cages containing excess chicks. A single feed trough was present in each compartment against the side of the cage and outside the brooding area. The feed trough was 3.5 cm wide, 5 cm high, and 66 cm long. A 1-cm-wide horizontal lip was
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
ism resulted in highly significant decreases in beak-inflicted injuries (Kuo et ah, 1991; Craig, 1992a). Beak trimming effects on growth rate and feed intake vary from study to study (Gentle, 1986; Cunningham, 1992). Although the causes cannot be known, it seems that differences among studies, including such variables as age when beaks were trimmed, type of cut, severity of trimming, and temperature of the cauterizing blade may have been involved. Nevertheless, in most experiments, feed intake and growth were reduced for at least a brief period after trimming, and then those effects diminished gradually (Cunningham, 1992). Lower feed usage by beak-trimmed birds may be associated with causative factors of a physiological nature (Gentle, 1986). Comparisons of behavior of intact and beak-trimmed birds and casual observations of the amount of feed apparently displaced from feeders suggest that intact hens have greater wastage than beaktrimmed hens (Lee and Reid, 1977; HarterDennis and Pescatore, 1986; Blokhuis et al, 1987; Lee and Craig, 1990). Apparently, feed wastage has not been measured with reference to beak trimming, and feed intake and feed wastage (if it occurred) relative to beak treatment have been confounded in studies carried out to date. In the experiments reported here, a major objective was to compare pullets whose beaks were not trimmed with other pullets whose beaks were trimmed either once or twice. Three genetic stocks were used to determine whether beak trimming by stock interactions were involved. The effects of beak treatment were estimated in terms of regrowth of beaks, feed intake, feed wastage, growth prior to egg production, egg production over 2-wk periods before pullets were 1 yr old, and the efficiency of feed usage for growth and egg production.
1831
1832
CRAIG ET AL.
on the side attached to the cage; and 66 cm long. The trough side next to the cage was vertical, and there was a 1-cm-wide lip angling inward and upward at the top of the outer edge. Cages were in a light-controlled room having a heater with a thermostatic control. Room lights were controlled automatically and were set to a 24-h photoperiod during the first 2 wk. Beginning at that time, the photoperiod was reduced 2 h daily until lights were on for the 12-h period from 0700 to 1900 h. During 4-day periods when feed intake and wastage were measured, an attempt was made to minimize feed wastage, without restricting feed intake, by keeping feed troughs between one-third and onefourth full at all times. To achieve this, feed was leveled and added at regular intervals three or four times per day as required. Even when troughs were only one-fourth full, pullets did not appear to strike their beaks against bottoms of troughs. During feed measurement periods, metal pans beneath cages were covered with paper and pulled out to extend 15 cm beyond the outer edge of feeder troughs to catch any feed spilling over the edge. Paper covers were replaced daily, and feed mat had been spilled was separated from excreta and weighed. Pullets tended to rake feed inwards, and feeding occurred primarily on the side of the feeder attached to the cage. Spillage that occurred was usually towards the interior and most wasted feed fell through the wire floor just inside the cage onto the collecting pan below. Phase 1 body weight and feed usage data were obtained over 4-day periods beginning immediately after beak trirriming (IN versus IX) at 9 days of age (Week 1) and measurements were repeated three times at biweekly intervals designated as Week 3, Week 5, and Week 7, until pullets were 55 days old. Similar measurements were obtained during Phase 2, beginning after the second trimming of beaks to produce the 2X beak treatment at 65 days of age (Week 9). Measurements during Phase 2 were repeated at 3-wk intervals and are designated as Week 12 and Week 15. Measurements were made on upper 9 Lyon Electric Co. Super Debeaker®, Lyon Electric beaks only when pullets were 13 days old. Both beaks were measured at 37 days Co., Inc., Chula Vista, CA 92010.
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
turned inward to minimize wastage of feed. Prior to beak trimming and during intervals between feeding trials, the feed trough was filled to near capacity. A single trough of the same dimensions containing water was also present and was placed against the opposite side of the compartment from the feeder. At 9 days of age, beaks of pullets in one of the two adjacent compartments on each deck were trimmed using an electric cauterizing debeaker.9 Fifty-six percent of the upper beak and slightly less of the lower beak were removed. Pullets that had their beaks trimmed were designated IX; those whose beaks were left intact were designated IN. All chicks were handled at 9 days, whether beaks were trimmed or not. At 32 days of age, pullets were moved to cages in four, four-deck, rearing batteries having three cages per deck. Experimental chicks were placed in the top, second, and third decks, and excess chicks in bottom deck cages. An empty cage separated IN and IX pullets of the same stock on each deck. At 55 days, after chicks were weighed, group size was reduced to seven per cage by random selection based on previously designated wing band numbers. Excess IN chicks and a single IX chick were removed from each deck, and the remaining 14 IX pullets were subdivided into two groups of 7 each. All three groups of the same strain were then moved to different cages but remained on the same deck in each battery. At 65 days, IX pullets in one cage of each deck and battery had their beaks retrimmed so as to shorten them to one-third the length of the beaks of IN pullets (these were designated as 2X pullets). After this procedure there were 28 chicks per genetic stockbeak treatment combination (four replicates of seven chicks each). All experimental pullets were weighed and returned to their cages at 65 days. Rearing cages measured 68.6 by 68.6 cm and had feeding and watering troughs hung on their front and rear sides, respectively. Troughs were 8 and 10 cm wide at the bottom and top, respectively; 7 cm deep
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
1833
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
during Phase 1 and at 65, 86, and 117 days appeared to adapt well to the floor pens. during Phase 2 of the rearing period. Upper When 32 wk old, seven pullets from each beaks were measured from the anterior end floor pen were placed in experimental cages of the nostril to the tip and lower beaks from each of the three rows of pens, and from a point directly under the anterior end each row of cages contained a single cage of of the nostril to the tip. each treatment combination. Empty cages Experiment 2. In Experiment 2, pullets were between occupied ones, so that acof the three genetic stocks were reared curate records of feed consumption could intermingled in 305 by 488 cm floor pens be obtained. Birds could not reach feed with 40 of each stock present in each of 15 between experimental cages. After a pens (120 pullets per pen). Floor area, 4-wk adjustment period, during which feeder space, and nipple waterers per pullet pullets dying or not doing well were were at or just above the minimums replaced, the number of pullets per cage recommended by the Guide for the Care and was reduced to six. Cages were 61 cm wide Use of Agricultural Animals in Agricultural by 45.7 cm deep and feed was available Research and Teaching (Consortium, 1988). from troughs along the aisle. Each pullet The house was curtain-sided so that natural had 465 cm2 floor area and 10.2 cm feeder light was present along with artificial lights. space. Water was supplied by two nipple Lights were on constantly for the first 2 waterers per cage. days. After that, the artificial light phoWhen pullets were 36 wk of age, beak toperiod was 21 h and 20 min during the 1st length and body weight data were obwk and was decreased by 20 min/wk until tained. From 36 to 38 wk, a rearing-cage pullets of the three stocks were placed in feeder trough was placed inside the regular layer-house cages at 16 wk of age. and larger feed trough. The inner trough At 10 days, all pullets in 10 of the 15 pens had feed leveled and added at regular had approximately two-thirds of their up- intervals, so that it was kept one-half to oneper beak and slightly less of the lower beak third full. Essentially all feed displaced removed using the same technique and from the smaller troughs appeared to be equipment as for the cage-reared pullets of caught in the larger trough. That feed was Experiment 1. At 9 wk, pullets in five of then returned to the inner trough so that these pens had their beaks retrimmed to feed intake could be measured accurately. shorten them to about one-third the length Records also were kept daily over the of beaks of IN pullets. Pullets in all pens 14-day period for number and weight of (including intact pullets) were inventoried eggs by cages. at 10 days and at 9 wk when beaks were Experiment 2. At 16 wk, pullets reared trimmed in some pens. in floor pens were separated by genetic Beak lengths and body weights were stock and beak treatment, and groups of six recorded for about 30% of all chicks in each were placed in 50.8 cm wide by 45.7 cm pen by measuring and weighing a sample deep layer cages. Feed was available along of chicks having wing-band numbers end- the aisle, and pullets had access to two ing in 0,5, and 9. Those data were obtained nipple waterers shared with adjoining at 38 days in five IN and five IX pens during cages on each side. Therefore, each pullet Phase 1 and for all pens at 66 and 117 days had 387 cm2 of floor area and 8.5 cm of during Phase 2 of the growing period. feeder space. Each genetic stock-beak treatment combination was assigned randomly to 3 cages in each of eight rows of cages (24 Adolescent-Early Adult Period cages per treatment combination). Beak Experiment 1. The W36 and W77 pullets length and body weight data were obtained were moved at 17 wk of age to small floor when pullets were 20 and 32 wk old by pens in a layer house. Pullets within a pen removing and weighing a single randomly were all of the same stock-beak treatment selected pullet from each experimental group, and each of three rows of pens cage. contained one pen each of the six treatment At 312 days (44 wk of age), all pullets groups. No measurements were taken be- from cages in which death had occurred tween 17 and 32 wk, but the pullets earlier and all pullets that were not needed
1834
CRAIG ET AL.
TABLE 1. Effects of beak treatment1 on beak lengths during rearing, late adolescent, and early adult periods in Experiments 1 and 2
Age (days)
(wk)
13 37 65 86 117 255
5 9 12 16 36
Uppe:r beak treatment IX 2X
IN
IN
Lower beak treatment IX
2X
7.7 10.0 11.9 13.2 14.1
6.2 9.9 11.2 12.9
(mm'l Experiment 1 8.22 12.9 16.5 17.9 18.6 19.2
»* ** *•
** »» 44
3.6 6.8 9.0 10.4 10.9 12.0
44 44 44 44
11.02 14.0 14.9 15.1 16.1
44 44 44 44 44
** ** ** **
44 44 7.2 7.6 10.7 5 12.5 38 44 44 44 9 15.9 8.8 5.3 10.8 ** 6.3 66 13.6 44 44 44 16 18.4 10.4 6.8 13.4 ** 11.1 117 15.7 44 44 44 20 18.7 10.7 8.3 13.3 NS 12.6 145 15.1 44 44 44 32 19.5 11.6 9.9 13.6 NS 14.0 226 15.7 *IN = no trimming; beaks were intact; IX = beaks trimmed once: about 56 and 67% of the upper and slightly less of the lower beak removed at 9 and 10 days of age in Experiments 1 and 2; 2X = beaks trimmed twice: second beak trimming of a sample of IX pullets at 9 wk to shorten beak length to one-third that of IN pullets at that age. 2 Upper beaks were measured from the anterior end of the nostril to the tip and lower beaks from a point directly under the anterior end of the nostril to the tip. **P £ .01 between beak lengths in adjacent columns.
for feed usage data collection were removed from four of the eight rows of cages. Alternate cages were then filled in those four rows, so that pullets in three cages per row represented each of the following genetic stock-beak treatment combinations: W36-IN, W36-2X, W77-IN, and W77-2X. Thus, there were 12 cages for each combination. Pullets retained for further study were weighed as they were transferred to their new cage locations. Further information on feed usage was obtained over a 14-day period when pullets were 46 to 48 wk old. Rearing-cage feed troughs were placed inside the regular and larger feed troughs and procedures and measures of feed intake and egg production were obtained in the same manner as with Experiment 1 pullets. In addition, information on feed wastage only was collected during an additional 3-day period, following the 14-day test, by collecting and weighing all feed spilling into the larger trough.
among means of treatment groups. Data points consisted of cage means, and a randomized complete block analysis for single measures or for repeated measures was carried out, as was appropriate. Each phase of the rearing period was analyzed separately in Experiment 1, and analyses were carried out within age periods when beak treatment by age interactions were found. Analysis within age periods was used exclusively in Experiment 2. When significant differences among means were indicated within ages, least significant differences were calculated and applied to determine which pairs of means differed. RESULTS AND DISCUSSION
Beak length measurements for the three beak treatments are presented in Table 1. Data were pooled over stocks because stock by beak treatment interactions were absent. Both upper and lower beaks in IX pullets remained shorter than those of IN pullets throughout the study in both Statistical Analysis experiments. However, relative differences All data were subjected to analysis of decreased over time. Initially, IX pullets in variance to test for significant differences Experiment 1 had upper beaks about 44%
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
5.4 7.1 7.5 8.7 Experiment 2 -
1835
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
TABLE 2. Effects of beak treatment1 on body weights during rearing, late adolescent, and early adult periods in Experiments 1 and 2 Age (days)
IN
2X
IX
(wk)
(g) Experiment 1
3 5 7 9 12 15 36
38 66 117 145 226 312
5 9 16 20 32 44
110 250 »* 447 »» 660 ** 843 ** 1,095 1,241 » 1,627 NS Experiment 2 372 733 NS 1,207 NS 1,547 NS 1,608 1,742
99 235 422 633 823 1,080 1,231 1,579
NS
357 720 1,184 1,506 1,548
NS NS
735 1,021 1,199 1,550
1,138 1,4842 1,5422 1,6492
X IN = no trimming; beaks were intact; IX = beaks trimmed once: about 56% and 67% of the upper and slightly less of the lower beak removed at 9 and 10 days of age in Experiments 1 and 2; 2X = beaks trimmed twice: second beak trimming of a sample of IX pullets at 9 wk to shorten beak length to one-third that of IN pullets at that age. 2 P < .05 for difference between IN and 2X. *P < .05 between body weights in adjacent columns. **P < .01 between body weights in adjacent columns.
as long as those of IN pullets, but by 36 when compared with IN pullets (Table 1). wk they were 63% as long. In Experiment The 2X pullets' beaks were also consis2, measurements of upper beak lengths on tently shorter than those of IX pullets in a sample of chicks (data not shown), taken Experiment 1, but lower beaks of 2X at 10 days, indicated that IX chicks' beaks pullets did not differ significantly in were 33% as long as those of IN chicks. By length from those of IX pullets at 20 or 32 32 wk, IX chicks' upper beaks averaged wk of age in Experiment 2. Although 2X 59% as long as those of IN pullets. pullets' beaks continued to remain shorter Numerous authors have noted regrowth than those of both IN and IX pullets (with of trimmed beaks (Gentle, 1986; Cunnin- the exceptions for 2X and IX lower beaks gham, 1992), and Kuo et al. (1991) argued, noted above) throughout both experion the basis of different studies carried out ments, the relative difference also deat the authors' station, that the kind of cut creased with increasing age. may affect regrowth; V-shaped cuts (as Body weights were obtained beginning viewed from the side) appeared to have soon after beak trirruning was carried out more lasting effects than vertical cuts or and periodically through the young adult "block" debeaking. Commercial breeders phase (Table 2). As with beak lengths, data commonly recommend beak trimming of were pooled over genetic stocks because young egg-strain pullets at least once (Hy- of absence of detectable beak treatment by Line International, 1990a) and a second genetic stock interactions. Differences trimming is frequently recommended also were present between IX and IN pullets (Hy-Line International, 1990b, H&N Inter- initially in both experiments but dinational, 1992). minished gradually over the rearing Pullets whose beaks were trimmed period. Thus, IX pullets of Experiment 1, twice (2X) also had shorter upper and which were only 90% as heavy 4 days lower beak lengths throughout the study after beak trimming, were 99% as heavy at
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
13 27 41 55 69 86 111 255
1836
CRAIG ET Ah.
TABLE 3. Effects of beak treatment, genetic stock, and age on daily weight gain and feed usage from 9 days to 8 wk of age (Phase 1) in Experiment 1
Comparison
Daily gain
Feed efficiency1
FeedI usage, daily Eaten
Wasted
Total
Eaten
-(g)
-
(g=g)
12.7a 11.7b
37.9' 35.3b
1.0* .2b
39.0a 35.6b
2.9* 2.9*
2.9a 2.9*
12.2a 12.5" 11.8"
36.6* 36.7* 36.7a
.5 a 1.0* .4a
37.1b 37.6a 37.1b
2.9a 2.8a 3.0a
2.9* 2.9* 3.0*
6.3-1 10.6= 16.5* 15.4b
13.8
1992 Poultry Science 71:1830-1841
ticosteroid levels were lower and adrenal and thyroid gland weights were lighter for Neurophysiological and behavioral ob- beak-trimmed hens than for hens with servations provide indirect evidence that intact beaks, thereby suggesting that those beak trimming of pullets causes pain, with trimmed beaks were under less which apparently persists for weeks or stress. The argument in favor of beak even months (Breward and Gentle, 1985; trirruning has been that, if properly done, Duncan et ah, 1989; Craig and Lee, 1990; beak trirnming provides insurance against Gentle et al, 1990; Lee and Craig, 1990, feather and cannibalistic pecking, which 1991). Therefore, it is surprising that are otherwise likely to occur among hens Eskland (1981) found that plasma cor- kept for egg production (Consortium, 1988). Recent studies suggest that at least one stock of White Leghorns does not require Received for publication May 11, 1992. beak trimming (Craig and Lee, 1990; Accepted for publication July 20, 1992. Contribution Number 92-565-J, Kansas Agricul- Craig, 1992b), and Gentle (1986) reported tural Experiment Station, Manhattan, Kansas 66506. that a commercial breeder of brown egg 2 This investigation is part of the Kansas contribu- layers recommended that customers tion to the NC-168 Regional Poultry Project. should not beak trim birds of their stock. department of Animal Sciences and Industry. 4 To whom correspondence should be addressed. Other recent studies report evidence that kin selection among intact hens of stocks sVolunteer. susceptible to heavy losses from cannibaldepartment of Statistics. INTRODUCTION
1830
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
ABSTRACT Two experiments were conducted to compare beak treatment effects on pullets of three genetic stocks. Within each stock, equal numbers were assigned to three treatments: no beak trimming (IN), beak trimming once (IX), and beak trimming twice (2X). Beak treatment, genetic stock, and age effects along with interactions among main effects were examined for productionassociated traits during rearing and brief periods of early egg production. Beaks of IX and 2X pullets remained shorter than those of IN pullets through final measurements at 36 and 32 wk of age in Experiments 1 and 2, respectively. However, differences in beak length decreased as age increased. Upper beaks of 2X pullets remained shorter than those of IX pullets, but lower beaks of IX and 2X pullets did not differ by 20 wk in Experiment 2. Weight gains, feed usage, and efficiency of growth were affected by beak treatments. Beak trimming reduced gains, feed eaten, feed wasted, and total feed used, and 2X pullets used their feed more efficiently for weight gain and egg production. A general decrease occurred in differences among beak treatments for weight gains, feed eaten, feed wasted, and efficiency of gains with increasing age during rearing. Nevertheless, significant differences in feed consumed, feed wasted, and efficiency of feed used for egg production indicated an economic advantage in favor of beak trimming. (Key words: beak trimming, genetic stocks, feed usage, growth, egg production)
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
THy-Line International, Dallas Center, IA 50063. H&N International, Redmond, WA 98052.
8
MATERIALS AND METHODS Three genetic stocks were used: HyLine® W-36 (W36),7 Hy-Line® W-77 (W77),7 and Strain N. The W36 and W77 hatching eggs were obtained directly from the breeder. The N hatching eggs were produced at the authors' station by mating together randomly chosen males and females from H&N Nick Chick®8 foundation stock following two generations of relaxed selection. Ages of W36 and W77 parental stocks were unknown, but hatching eggs were obtained from different flocks and it is likely that hatchery flock hens of the three stocks differed in age as well as other unidentified variables. Indirect evidence (size of hatching eggs) suggests that older hens of W36 than of W77 were used and that N hens were the youngest of the three stocks. Approximately 2,100 eggs of each stock were set simultaneously in the same incubator. At hatching, chicks were wingbanded, sexed, cockerels were disposed of humanely, and pullets were vaccinated for Marek's disease. Subsequent vaccinations and rations used were the same as those indicated by Okpokho et al. (1987). Feed was always provided in the form of mash. Rearing Period Experiment 1. Experimental pullets were placed in the second through fourth decks of four, six-deck, battery brooders having two cages on each deck. The top decks contained excess chicks. Within each battery brooder, 15 experimental chicks of the same stock occupied each of the two cages of a single, randomly selected deck. Thus, 30 chicks of each stock were used in each of four battery brooders so that a total of 360 chicks was involved. Compartments were 68.6 cm wide by 99.1 cm long, including a heated brooding area of 30.5 by 68.6 cm. A. few pullets that died or lost their wing bands during the first 9 days were replaced by pullets of the same stock from cages containing excess chicks. A single feed trough was present in each compartment against the side of the cage and outside the brooding area. The feed trough was 3.5 cm wide, 5 cm high, and 66 cm long. A 1-cm-wide horizontal lip was
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
ism resulted in highly significant decreases in beak-inflicted injuries (Kuo et ah, 1991; Craig, 1992a). Beak trimming effects on growth rate and feed intake vary from study to study (Gentle, 1986; Cunningham, 1992). Although the causes cannot be known, it seems that differences among studies, including such variables as age when beaks were trimmed, type of cut, severity of trimming, and temperature of the cauterizing blade may have been involved. Nevertheless, in most experiments, feed intake and growth were reduced for at least a brief period after trimming, and then those effects diminished gradually (Cunningham, 1992). Lower feed usage by beak-trimmed birds may be associated with causative factors of a physiological nature (Gentle, 1986). Comparisons of behavior of intact and beak-trimmed birds and casual observations of the amount of feed apparently displaced from feeders suggest that intact hens have greater wastage than beaktrimmed hens (Lee and Reid, 1977; HarterDennis and Pescatore, 1986; Blokhuis et al, 1987; Lee and Craig, 1990). Apparently, feed wastage has not been measured with reference to beak trimming, and feed intake and feed wastage (if it occurred) relative to beak treatment have been confounded in studies carried out to date. In the experiments reported here, a major objective was to compare pullets whose beaks were not trimmed with other pullets whose beaks were trimmed either once or twice. Three genetic stocks were used to determine whether beak trimming by stock interactions were involved. The effects of beak treatment were estimated in terms of regrowth of beaks, feed intake, feed wastage, growth prior to egg production, egg production over 2-wk periods before pullets were 1 yr old, and the efficiency of feed usage for growth and egg production.
1831
1832
CRAIG ET AL.
on the side attached to the cage; and 66 cm long. The trough side next to the cage was vertical, and there was a 1-cm-wide lip angling inward and upward at the top of the outer edge. Cages were in a light-controlled room having a heater with a thermostatic control. Room lights were controlled automatically and were set to a 24-h photoperiod during the first 2 wk. Beginning at that time, the photoperiod was reduced 2 h daily until lights were on for the 12-h period from 0700 to 1900 h. During 4-day periods when feed intake and wastage were measured, an attempt was made to minimize feed wastage, without restricting feed intake, by keeping feed troughs between one-third and onefourth full at all times. To achieve this, feed was leveled and added at regular intervals three or four times per day as required. Even when troughs were only one-fourth full, pullets did not appear to strike their beaks against bottoms of troughs. During feed measurement periods, metal pans beneath cages were covered with paper and pulled out to extend 15 cm beyond the outer edge of feeder troughs to catch any feed spilling over the edge. Paper covers were replaced daily, and feed mat had been spilled was separated from excreta and weighed. Pullets tended to rake feed inwards, and feeding occurred primarily on the side of the feeder attached to the cage. Spillage that occurred was usually towards the interior and most wasted feed fell through the wire floor just inside the cage onto the collecting pan below. Phase 1 body weight and feed usage data were obtained over 4-day periods beginning immediately after beak trirriming (IN versus IX) at 9 days of age (Week 1) and measurements were repeated three times at biweekly intervals designated as Week 3, Week 5, and Week 7, until pullets were 55 days old. Similar measurements were obtained during Phase 2, beginning after the second trimming of beaks to produce the 2X beak treatment at 65 days of age (Week 9). Measurements during Phase 2 were repeated at 3-wk intervals and are designated as Week 12 and Week 15. Measurements were made on upper 9 Lyon Electric Co. Super Debeaker®, Lyon Electric beaks only when pullets were 13 days old. Both beaks were measured at 37 days Co., Inc., Chula Vista, CA 92010.
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
turned inward to minimize wastage of feed. Prior to beak trimming and during intervals between feeding trials, the feed trough was filled to near capacity. A single trough of the same dimensions containing water was also present and was placed against the opposite side of the compartment from the feeder. At 9 days of age, beaks of pullets in one of the two adjacent compartments on each deck were trimmed using an electric cauterizing debeaker.9 Fifty-six percent of the upper beak and slightly less of the lower beak were removed. Pullets that had their beaks trimmed were designated IX; those whose beaks were left intact were designated IN. All chicks were handled at 9 days, whether beaks were trimmed or not. At 32 days of age, pullets were moved to cages in four, four-deck, rearing batteries having three cages per deck. Experimental chicks were placed in the top, second, and third decks, and excess chicks in bottom deck cages. An empty cage separated IN and IX pullets of the same stock on each deck. At 55 days, after chicks were weighed, group size was reduced to seven per cage by random selection based on previously designated wing band numbers. Excess IN chicks and a single IX chick were removed from each deck, and the remaining 14 IX pullets were subdivided into two groups of 7 each. All three groups of the same strain were then moved to different cages but remained on the same deck in each battery. At 65 days, IX pullets in one cage of each deck and battery had their beaks retrimmed so as to shorten them to one-third the length of the beaks of IN pullets (these were designated as 2X pullets). After this procedure there were 28 chicks per genetic stockbeak treatment combination (four replicates of seven chicks each). All experimental pullets were weighed and returned to their cages at 65 days. Rearing cages measured 68.6 by 68.6 cm and had feeding and watering troughs hung on their front and rear sides, respectively. Troughs were 8 and 10 cm wide at the bottom and top, respectively; 7 cm deep
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
1833
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
during Phase 1 and at 65, 86, and 117 days appeared to adapt well to the floor pens. during Phase 2 of the rearing period. Upper When 32 wk old, seven pullets from each beaks were measured from the anterior end floor pen were placed in experimental cages of the nostril to the tip and lower beaks from each of the three rows of pens, and from a point directly under the anterior end each row of cages contained a single cage of of the nostril to the tip. each treatment combination. Empty cages Experiment 2. In Experiment 2, pullets were between occupied ones, so that acof the three genetic stocks were reared curate records of feed consumption could intermingled in 305 by 488 cm floor pens be obtained. Birds could not reach feed with 40 of each stock present in each of 15 between experimental cages. After a pens (120 pullets per pen). Floor area, 4-wk adjustment period, during which feeder space, and nipple waterers per pullet pullets dying or not doing well were were at or just above the minimums replaced, the number of pullets per cage recommended by the Guide for the Care and was reduced to six. Cages were 61 cm wide Use of Agricultural Animals in Agricultural by 45.7 cm deep and feed was available Research and Teaching (Consortium, 1988). from troughs along the aisle. Each pullet The house was curtain-sided so that natural had 465 cm2 floor area and 10.2 cm feeder light was present along with artificial lights. space. Water was supplied by two nipple Lights were on constantly for the first 2 waterers per cage. days. After that, the artificial light phoWhen pullets were 36 wk of age, beak toperiod was 21 h and 20 min during the 1st length and body weight data were obwk and was decreased by 20 min/wk until tained. From 36 to 38 wk, a rearing-cage pullets of the three stocks were placed in feeder trough was placed inside the regular layer-house cages at 16 wk of age. and larger feed trough. The inner trough At 10 days, all pullets in 10 of the 15 pens had feed leveled and added at regular had approximately two-thirds of their up- intervals, so that it was kept one-half to oneper beak and slightly less of the lower beak third full. Essentially all feed displaced removed using the same technique and from the smaller troughs appeared to be equipment as for the cage-reared pullets of caught in the larger trough. That feed was Experiment 1. At 9 wk, pullets in five of then returned to the inner trough so that these pens had their beaks retrimmed to feed intake could be measured accurately. shorten them to about one-third the length Records also were kept daily over the of beaks of IN pullets. Pullets in all pens 14-day period for number and weight of (including intact pullets) were inventoried eggs by cages. at 10 days and at 9 wk when beaks were Experiment 2. At 16 wk, pullets reared trimmed in some pens. in floor pens were separated by genetic Beak lengths and body weights were stock and beak treatment, and groups of six recorded for about 30% of all chicks in each were placed in 50.8 cm wide by 45.7 cm pen by measuring and weighing a sample deep layer cages. Feed was available along of chicks having wing-band numbers end- the aisle, and pullets had access to two ing in 0,5, and 9. Those data were obtained nipple waterers shared with adjoining at 38 days in five IN and five IX pens during cages on each side. Therefore, each pullet Phase 1 and for all pens at 66 and 117 days had 387 cm2 of floor area and 8.5 cm of during Phase 2 of the growing period. feeder space. Each genetic stock-beak treatment combination was assigned randomly to 3 cages in each of eight rows of cages (24 Adolescent-Early Adult Period cages per treatment combination). Beak Experiment 1. The W36 and W77 pullets length and body weight data were obtained were moved at 17 wk of age to small floor when pullets were 20 and 32 wk old by pens in a layer house. Pullets within a pen removing and weighing a single randomly were all of the same stock-beak treatment selected pullet from each experimental group, and each of three rows of pens cage. contained one pen each of the six treatment At 312 days (44 wk of age), all pullets groups. No measurements were taken be- from cages in which death had occurred tween 17 and 32 wk, but the pullets earlier and all pullets that were not needed
1834
CRAIG ET AL.
TABLE 1. Effects of beak treatment1 on beak lengths during rearing, late adolescent, and early adult periods in Experiments 1 and 2
Age (days)
(wk)
13 37 65 86 117 255
5 9 12 16 36
Uppe:r beak treatment IX 2X
IN
IN
Lower beak treatment IX
2X
7.7 10.0 11.9 13.2 14.1
6.2 9.9 11.2 12.9
(mm'l Experiment 1 8.22 12.9 16.5 17.9 18.6 19.2
»* ** *•
** »» 44
3.6 6.8 9.0 10.4 10.9 12.0
44 44 44 44
11.02 14.0 14.9 15.1 16.1
44 44 44 44 44
** ** ** **
44 44 7.2 7.6 10.7 5 12.5 38 44 44 44 9 15.9 8.8 5.3 10.8 ** 6.3 66 13.6 44 44 44 16 18.4 10.4 6.8 13.4 ** 11.1 117 15.7 44 44 44 20 18.7 10.7 8.3 13.3 NS 12.6 145 15.1 44 44 44 32 19.5 11.6 9.9 13.6 NS 14.0 226 15.7 *IN = no trimming; beaks were intact; IX = beaks trimmed once: about 56 and 67% of the upper and slightly less of the lower beak removed at 9 and 10 days of age in Experiments 1 and 2; 2X = beaks trimmed twice: second beak trimming of a sample of IX pullets at 9 wk to shorten beak length to one-third that of IN pullets at that age. 2 Upper beaks were measured from the anterior end of the nostril to the tip and lower beaks from a point directly under the anterior end of the nostril to the tip. **P £ .01 between beak lengths in adjacent columns.
for feed usage data collection were removed from four of the eight rows of cages. Alternate cages were then filled in those four rows, so that pullets in three cages per row represented each of the following genetic stock-beak treatment combinations: W36-IN, W36-2X, W77-IN, and W77-2X. Thus, there were 12 cages for each combination. Pullets retained for further study were weighed as they were transferred to their new cage locations. Further information on feed usage was obtained over a 14-day period when pullets were 46 to 48 wk old. Rearing-cage feed troughs were placed inside the regular and larger feed troughs and procedures and measures of feed intake and egg production were obtained in the same manner as with Experiment 1 pullets. In addition, information on feed wastage only was collected during an additional 3-day period, following the 14-day test, by collecting and weighing all feed spilling into the larger trough.
among means of treatment groups. Data points consisted of cage means, and a randomized complete block analysis for single measures or for repeated measures was carried out, as was appropriate. Each phase of the rearing period was analyzed separately in Experiment 1, and analyses were carried out within age periods when beak treatment by age interactions were found. Analysis within age periods was used exclusively in Experiment 2. When significant differences among means were indicated within ages, least significant differences were calculated and applied to determine which pairs of means differed. RESULTS AND DISCUSSION
Beak length measurements for the three beak treatments are presented in Table 1. Data were pooled over stocks because stock by beak treatment interactions were absent. Both upper and lower beaks in IX pullets remained shorter than those of IN pullets throughout the study in both Statistical Analysis experiments. However, relative differences All data were subjected to analysis of decreased over time. Initially, IX pullets in variance to test for significant differences Experiment 1 had upper beaks about 44%
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
5.4 7.1 7.5 8.7 Experiment 2 -
1835
FEED USAGE OF INTACT AND BEAK-TRIMMED PULLETS
TABLE 2. Effects of beak treatment1 on body weights during rearing, late adolescent, and early adult periods in Experiments 1 and 2 Age (days)
IN
2X
IX
(wk)
(g) Experiment 1
3 5 7 9 12 15 36
38 66 117 145 226 312
5 9 16 20 32 44
110 250 »* 447 »» 660 ** 843 ** 1,095 1,241 » 1,627 NS Experiment 2 372 733 NS 1,207 NS 1,547 NS 1,608 1,742
99 235 422 633 823 1,080 1,231 1,579
NS
357 720 1,184 1,506 1,548
NS NS
735 1,021 1,199 1,550
1,138 1,4842 1,5422 1,6492
X IN = no trimming; beaks were intact; IX = beaks trimmed once: about 56% and 67% of the upper and slightly less of the lower beak removed at 9 and 10 days of age in Experiments 1 and 2; 2X = beaks trimmed twice: second beak trimming of a sample of IX pullets at 9 wk to shorten beak length to one-third that of IN pullets at that age. 2 P < .05 for difference between IN and 2X. *P < .05 between body weights in adjacent columns. **P < .01 between body weights in adjacent columns.
as long as those of IN pullets, but by 36 when compared with IN pullets (Table 1). wk they were 63% as long. In Experiment The 2X pullets' beaks were also consis2, measurements of upper beak lengths on tently shorter than those of IX pullets in a sample of chicks (data not shown), taken Experiment 1, but lower beaks of 2X at 10 days, indicated that IX chicks' beaks pullets did not differ significantly in were 33% as long as those of IN chicks. By length from those of IX pullets at 20 or 32 32 wk, IX chicks' upper beaks averaged wk of age in Experiment 2. Although 2X 59% as long as those of IN pullets. pullets' beaks continued to remain shorter Numerous authors have noted regrowth than those of both IN and IX pullets (with of trimmed beaks (Gentle, 1986; Cunnin- the exceptions for 2X and IX lower beaks gham, 1992), and Kuo et al. (1991) argued, noted above) throughout both experion the basis of different studies carried out ments, the relative difference also deat the authors' station, that the kind of cut creased with increasing age. may affect regrowth; V-shaped cuts (as Body weights were obtained beginning viewed from the side) appeared to have soon after beak trirruning was carried out more lasting effects than vertical cuts or and periodically through the young adult "block" debeaking. Commercial breeders phase (Table 2). As with beak lengths, data commonly recommend beak trimming of were pooled over genetic stocks because young egg-strain pullets at least once (Hy- of absence of detectable beak treatment by Line International, 1990a) and a second genetic stock interactions. Differences trimming is frequently recommended also were present between IX and IN pullets (Hy-Line International, 1990b, H&N Inter- initially in both experiments but dinational, 1992). minished gradually over the rearing Pullets whose beaks were trimmed period. Thus, IX pullets of Experiment 1, twice (2X) also had shorter upper and which were only 90% as heavy 4 days lower beak lengths throughout the study after beak trimming, were 99% as heavy at
Downloaded from http://ps.oxfordjournals.org/ at Pennsylvania State University on May 24, 2015
13 27 41 55 69 86 111 255
1836
CRAIG ET Ah.
TABLE 3. Effects of beak treatment, genetic stock, and age on daily weight gain and feed usage from 9 days to 8 wk of age (Phase 1) in Experiment 1
Comparison
Daily gain
Feed efficiency1
FeedI usage, daily Eaten
Wasted
Total
Eaten
-(g)
-
(g=g)
12.7a 11.7b
37.9' 35.3b
1.0* .2b
39.0a 35.6b
2.9* 2.9*
2.9a 2.9*
12.2a 12.5" 11.8"
36.6* 36.7* 36.7a
.5 a 1.0* .4a
37.1b 37.6a 37.1b
2.9a 2.8a 3.0a
2.9* 2.9* 3.0*
6.3-1 10.6= 16.5* 15.4b
13.8
