- Email: [email protected]
Motor ability and self-selection of an analgesic drug by fast-growing chickens
©2011 Poultry Science Association, Inc.
Motor ability and self-selection of an analgesic drug by fast-growing chickens P. B. Siegel,*1 S. J. Gustin,† and M. N. Katanbaf‡ *Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg 24061; †Cobb-Vantress Inc., Siloam Springs, AR 72761; and ‡Cobb-Vantress Inc., Monticello, KY 42633
SUMMARY Breeding programs designed for broiler production have resulted in a chicken that, when fully fed, grows rapidly and has a body conformation that enhances yield at market weight. Compared with chickens bred for high egg production, the motor ability of broilers has been compromised and is of increasing concern in broiler breeding and production. Broilers with intermediate gait scores of 2, 3, and 4 were provided choices among diets containing different doses of a nonsteroidal anti-inflammatory drug (carprofen). Broilers with no identifiable gait abnormality (score of 1) or unable to walk (score of 5) were excluded from the study. The hypothesis that broilers with higher gait scores, if experiencing pain, would prefer diets with higher doses of carprofen was rejected because no differences were observed in feed consumption among treatment groups. Although males and females responded similarly, there was an interaction of sex with left-right preference for feeder location. Key words: broiler, carprofen, choice feeding, gait 2011 J. Appl. Poult. Res. 20:249–252 doi:10.3382/japr.2009-00118
DESCRIPTION OF PROBLEM During the past 60+ yr, the dual-purpose chicken has been replaced by stocks bred specifically for the production of eggs or meat. These programs have contributed to distinct differences in the body types of egg and meat stocks. For broilers, changes in conformation, early growth rate, FE, and yield have been dramatic [1, 2]. These changes have influenced their motor ability and have generated considerable research interest that has taken several forms, with emphasis including anatomical factors [3–5], tibia dyschondroplasia and husbandry [6–10], pain [11–14], large field studies 1
Corresponding author: [email protected]
[15], and comprehensive reviews and discussion [16, 17]. That chickens, including broilers, can self-select feed to satisfy nutrient requirements is well documented from choice-feeding experiments [18–21]. Choice feeding was used to compare preferences by “lame” and “sound” broilers for diets containing the analgesic drug carprofen [14], with the assumption being that individuals experiencing pain should prefer diets containing the carprofen to a placebo. In this paper, we describe experiments designed to compare feed intake of fast-growing, high-yield broilers that differ in motor ability when fed diets with and without the analgesic drug carprofen.
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
Primary Audience: Behaviorists, Breeders, Production Managers, Veterinarians
JAPR: Research Report
250
MATERIALS AND METHODS Experiment 1
Experiment 2 The experimental protocol for this experiment was based on the results from experiment 1. Added to the main effects in experiment 1 were individuals with gait scores of 2, 3, and 4 [23]. The objective was to compare %ADFI among broilers with intermediate gait scores. Thus, of the 36 males and 36 females selected,
RESULTS AND DISCUSSION Experiment 1 A significant difference was observed in %ADFI among carprofen doses. The %ADFI for the 0-mg dose (1.97 ± 0.07) was intermediate and was not different from the 34.3 mg/kg of feed (2.11 ± 0.07) and the 102.9 mg/kg of feed (1.88 ± 0.07), which differed. Sex × laterality was the only significant interaction. This interaction occurred because although females had no left-right preference in %ADFI (2.00 ± 0.08 for left vs. 1.96 ± 0.07 for right), males had a significant preference for the left compared with the right feeder (2.25 ± 0.07 vs. 1.73 ± 0.07). Experiment 2 Analysis of variance of %ADFI for this experiment is presented in Table 1. None of the 14 higher order interactions and only 1 (sex × laterality) of the 10 first-order interactions was significant. The interaction was because although males showed no left-right preference (3.90 ± 0.15 for left vs. 4.14 ± 0.21 for right), females had a significant preference for the left compared with the right feeder (3.97 ± 0.13 vs. 3.52 ± 0.14). Means and SE for the other main effects (day, gait score, and carprofen dose) are summarized in Table 2. Fluctuation was observed among days, with %ADFI being less for d 3 than for d 2 and 4, which did not differ. For gait score, a trend was observed, with higher values for score 2 than 4 and the values for 3 being intermediate. Because intake was expressed relative to BW, those broilers with the lower gait score had a higher relative food intake. No differences were observed in %ADFI among carprofen dosages. We can conclude, based on the lack of a carprofen dose × gait score interaction, that
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
This experiment was designed to ascertain if training was necessary for broilers to discriminate among varying dosages of the nonsteroidal anti-inflammatory drug carprofen [22] in their feed. The main effects were dosage of carprofen (0, 34.3, or 102.9 mg/kg of feed), sex (male, female), and laterality (left, right). At 35 d of age, broilers from a large sex-intermingled flock reared on wood shavings, with feed and water available ad libitum, were individually weighed and gait scored (scores from 1 to 5) [23]. The scores used were a slight modification [9] of those described by Kestin et al. [3]. From broilers with a score of 3, we randomly selected 36 males and 36 females for transfer to preassigned individual cages [24]. Each cage was equipped with 2 feeders that contained feed at all times. The assignment of carprofen dosages was at random in a manner such that all combinations were available. To balance for laterality, the feed with the lowest dosage was on the left side for half the cages and on the right side for the other half. The basal diet [25] was a broiler finisher in pellet form. Carprofen [14, 22] at each dosage was mixed with 100 mL of distilled water and sprayed on the feed. For the 0-mg level, only 100 mL of water was sprayed on the feed. Feed consumption from each feeder was recorded daily on d 36, 37, and 38 (considered the training period). Individual BW were obtained again on d 39 and 43, with ADFI recorded for d 39 to 43. Because of variations in BW among individuals, the trait analyzed was ADFI corrected for BW (%ADFI). Data were analyzed using a split-plot design [26], with significance considered at P < 0.05.
12 males and 12 females had gait scores of 2, 3, or 4. Consistent with experiment 1, broilers at 35 d of age were weighed, gait scored, and transferred to preassigned cages. Their %ADFI was measured for d 37, 38, and 39 (i.e., d 2, 3, and 4 after caging). Data were analyzed using a split-plot design [26], with significance considered at P < 0.05.
Siegel et al.: MOTOR ABILITY OF BROILERS Table 1. Analysis of variance for %ADFI,1 experiment 2 df
Mean squares × 10−4
Sex (S) Gait (G) Feed type (FT) Day (D) Laterality (L) S×G S × FT S×D S×L G × FT G×D G×L FT × D FT × L D×L S × G × FT S×F×D S×D×L S×G×D S×G×L G × FT × D G × FT × L FT × D × L S × G × FT × D S × G × FT × L S×G×D×L S × FT × D × L G × FT × D × L S × G × FT × D × L
1 2 2 2 1 2 2 2 1 4 4 2 4 2 2 4 4 2 4 2 8 4 4 8 6 8 4 8 8
1.14 11.19** 0.05 11.14** 0.81 1.38 5.34 2.34 12.37** 1.13 0.76 1.61 1.74 2.01 2.89 0.81 0.73 5.36 0.15 1.73 1.06 3.67 1.37 1.72 1.82 2.59 0.22 1.73 1.88
1
%ADFI = ADFI corrected for BW. Sex (male, female), gait (score 2, 3, 4), feed type (carprofen dose of 0, 34.3, 102.9), day (2, 3, 4), and laterality (left, right). **P < 0.01. 2
among these treatment groups, no self-selection occurred for the feed containing the nonsteroidal anti-inflammatory analgesic.
Table 2. Means and SE for %ADFI1 by day, gait, and carprofen dose Item Day1 2 3 4 Gait score2 2 3 4 Carprofen dose, mg/kg of feed 0 34.3 102.9
4.05 ± 0.13a 3.56 ± 0.09b 4.04 ± 0.12a 4.17 ± 0.12a 3.86 ± 0.11ab 3.61 ± 0.12b 3.91 ± 0.13a 3.90 ± 0.11a 3.84 ± 0.12a
a,b
Means within a treatment with the same superscript are not different (P < 0.05). 1 %ADFI = ADFI corrected for BW. %ADFI was measured on d 2, 3, and 4 after caging. 2 See [23] for detailed descriptions.
population studied, individuals with intermediate gait scores did not exhibit a preference for a veterinary compound routinely prescribed for animals with joint pain. Although these results may appear inconsistent with results in which this was observed [12, 14, 17], it may be due in part to the testing procedures (traverse an obstacle course [12], feed color [14], vertical force [17]), underlying pathology, differences in activity levels of the broilers, or a combination of these factors, which could have altered the need to self-select the analgesic because of pain.
CONCLUSIONS AND APPLICATIONS
General We suggest, based on the lack of a preference among diets for chickens with gait scores of 2, 3, or 4, that although their motor ability may have been considered phenotypically compromised, it was not sufficient to elicit a preference for diets containing carprofen at these levels. Moreover, we did not measure a progression of gait scores over time. Pain is a vague term that is defined as “a state of physical or mental lack of well-being or physical or mental uneasiness that ranges from mild discomfort or dull distress to acute, often unbearable agony” [27]. For the
Mean ± SE
1. Individual broilers differed in their motor ability. Those with gait scores of 2, 3, and 4 did not exhibit a preference for an analgesic at the dosages used, suggesting that although abnormalities may have been identified, they were not sufficient for those chickens to prefer a diet containing an analgesic compound. 2. When given choices among diets, chickens exhibited laterality in dietary selection. The direction (left vs. right) was not necessarily predictable. Thus, laterality should be included in the experimental design of choice-feeding experiments. 3. Because no differences were observed among the intermediate gait scores, con-
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
Source of variation2
251
JAPR: Research Report
252 sideration should be given to reducing the classifications used in measuring the motor ability of meat-type poultry.
REFERENCES AND NOTES
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
1. Havenstein, G. B., P. R. Ferket, and M. A. Qureshi. 2003. Growth, liveability, and feed conversion of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poult. Sci. 82:1500–1508. 2. Emmerson, D. A., N. B. Anthony, K. E. Nester, and Y. M. Saif. 1991. Genetic association of selection for increased leg muscle and increased shank diameter with body composition and walking ability. Poult. Sci. 70:739–745. 3. Kestin, S. C., T. G. Knowles, A. E. Tinch, and N. G. Gregory. 1992. Prevalence of leg weakness in broiler chickens and its relationship with genotype. Vet. Rec. 131:190– 194. 4. Skinner-Noble, D. O., and R. G. Teeter. 2009. An examination of anatomic, physiologic, and metabolic factors associated with well-being of broilers differing in field gait score. Poult. Sci. 88:2–9. 5. Weeks, C. A., T. D. Danbury, H. C. Davies, P. Hunt, and S. C. Kestin. 2000. The behavior of broiler chickens and its modification by lameness. Appl. Anim. Behav. Sci. 67:111–125. 6. Sørensen, P., G. Su, and S. C. Kestin. 2000. Effects of age and stocking density on leg weakness in broiler chickens. Poult. Sci. 79:864–870. 7. Su, G., P. Sorenson, and S. C. Kestin. 1999. Meal feeding is more effective than early feed restriction at reducing the prevalence of leg weakness in broiler chickens. Poult. Sci. 78:949–955. 8. Sanotra, G. S., L. G. Lawson, and K. S. Vertergaard. 2001. Influence of stocking density on tonic immobility, lameness and tibial dyschondroplasia in broilers. J. Appl. Anim. Welf. Sci. 12:677–683. 9. Garner, J. P., C. Falcone, P. Wakenell, M. Martin, and J. A. Mench. 2002. Reliability and validity of a modified gait scoring system and its use in accessing tibial dyschondroplasia in broilers. Br. Poult. Sci. 43:355–363. 10. Blatchford, R. A., K. C. Klasing, H. L. Shivaprusad, P. S. Wakenell, G. S. Archer, and J. A. Mench. 2009. The effect of light intensity on the behavior, eye and leg health, and immune function of broiler chickens. Poult. Sci. 88:20–28. 11. Weary, D. M., L. Niel, C. F. Flower, and D. Fraser. 2006. Identifying and preventing pain in animals. Appl. Anim. Behav. Sci. 100:64–76. 12. McGeown, D., T. C. Danbury, A. E. Waterman-Pearson, and S. C. Kestin. 1999. Effect of carprofen on lameness in broiler chickens. Vet. Rec. 144:668–671. 13. Hocking, P. M., R. Bernard, and M. H. Maxwell. 1999. Assessment of pain during locomotion and the welfare of adult male turkeys with destructive cartilage loss of the hip joint. Br. Poult. Sci. 40:30–34.
14. Danbury, T. C., C. A. Weeks, J. P. Chambers, A. E. Waterman-Pearson, and S. C. Kestin. 2000. Self-selection of the analgesic drug carprofen by lame broiler chickens. Vet. Rec. 146:307–311. 15. Knowles, T. G., S. C. Kestin, S. M. Haslam, S. N. Brown, L. E. Green, A Butterworth, S. J. Pope, D. Pfeiffer, and C. J. Nicol. 2008. Leg disorders in broiler chickens: Prevalence, risk factors, and prevention. PLoS One 3:e1545. doi:10/1371/journal.pone.0001545. 16. Manning, L., S. C. Chadd, and R. N. Baines. 2007. Key health and welfare indicators for broiler performance. World’s Poult. Sci. J. 63:43–62. 17. Naas, I. A., I. C. L. A. Paz, M. S. Barache, G. Menezos, L. G. F. Bueno, I. C. L. Almeida, and D. T. Moura. 2009. Impact of lameness on broiler well-being. J. Appl. Poult. Res. 18:432–439. 18. Siegel, P. B., M. Picard, I. Nir, E. A. Dunnington, M. H. A. Willemson, and P. E. V. Williams. 1997. Responses of meat-type chickens to choice feeding of diets differing in protein and energy from hatch to market weight. Poult. Sci. 76:1183–1192. 19. Rose, S. P., and I. Kyriazakis. 1991. Diet selection in pigs and poultry. Proc. Nutr. Soc. 50:87–98. 20. Noble, D. O., M. L. Picard, E. A. Dunnington, G. Uzu, A. S. Larsen, and P. B. Siegel. 1993. Food intake adjustments of chicks: Short term reactions of genetic stocks to deficiencies in lysine, methionine or tryptophan. Br. Poult. Sci. 34:725–735. 21. Picard, M. L., G. Uzu, E. A. Dunnington, and P. B. Siegel. 1993. Food intake adjustments of chicks: Short term reactions to deficiencies in lysine, methionine and tryptophan. Br. Poult. Sci. 34:737–746. 22. Carprofen (Rimadyl, injectable, manufactured by Pfizer Animal Health, New York, NY) is a nonsteroidal antiinflammatory drug commonly used in veterinary practice to provide relief of joint pain by reducing inflammation by inhibiting production of cyclooxygenase-2 and other sources of inflammatory prostaglandins. 23. Gait scores: 1 = no identifiable abnormality; 2 = identifiable abnormality that has little impact on overall function; 3 = identifiable abnormality that impairs function; 4 = severe impairment of function, but still capable of walking; 5 = unable to walk. 24. Cages were 50.8 cm wide, 50.8 cm deep, and 61.0 cm high with plastic slatted floors. 25. Basal diet contained 19% CP and 3,208 kcal of ME/ kg of feed. 26. SAS Institute. 2003. Statistical Analysis Software Version 9.3.1. SAS Inst. Inc., Cary, NC, for split plot design. Sources of variation are shown in Table 1 for experiment 2. The analysis for experiment 1 is the same except that gait and interactions involving it were not sources of variation. Multiple means were compared by Duncan’s multiple range test. 27. Merriam-Webster. 1961. Webster’s 3rd New International Dictionary—Unabridged. G. & C. Merriam Co., Chicago, IL.
Motor ability and self-selection of an analgesic drug by fast-growing chickens P. B. Siegel,*1 S. J. Gustin,† and M. N. Katanbaf‡ *Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg 24061; †Cobb-Vantress Inc., Siloam Springs, AR 72761; and ‡Cobb-Vantress Inc., Monticello, KY 42633
SUMMARY Breeding programs designed for broiler production have resulted in a chicken that, when fully fed, grows rapidly and has a body conformation that enhances yield at market weight. Compared with chickens bred for high egg production, the motor ability of broilers has been compromised and is of increasing concern in broiler breeding and production. Broilers with intermediate gait scores of 2, 3, and 4 were provided choices among diets containing different doses of a nonsteroidal anti-inflammatory drug (carprofen). Broilers with no identifiable gait abnormality (score of 1) or unable to walk (score of 5) were excluded from the study. The hypothesis that broilers with higher gait scores, if experiencing pain, would prefer diets with higher doses of carprofen was rejected because no differences were observed in feed consumption among treatment groups. Although males and females responded similarly, there was an interaction of sex with left-right preference for feeder location. Key words: broiler, carprofen, choice feeding, gait 2011 J. Appl. Poult. Res. 20:249–252 doi:10.3382/japr.2009-00118
DESCRIPTION OF PROBLEM During the past 60+ yr, the dual-purpose chicken has been replaced by stocks bred specifically for the production of eggs or meat. These programs have contributed to distinct differences in the body types of egg and meat stocks. For broilers, changes in conformation, early growth rate, FE, and yield have been dramatic [1, 2]. These changes have influenced their motor ability and have generated considerable research interest that has taken several forms, with emphasis including anatomical factors [3–5], tibia dyschondroplasia and husbandry [6–10], pain [11–14], large field studies 1
Corresponding author: [email protected]
[15], and comprehensive reviews and discussion [16, 17]. That chickens, including broilers, can self-select feed to satisfy nutrient requirements is well documented from choice-feeding experiments [18–21]. Choice feeding was used to compare preferences by “lame” and “sound” broilers for diets containing the analgesic drug carprofen [14], with the assumption being that individuals experiencing pain should prefer diets containing the carprofen to a placebo. In this paper, we describe experiments designed to compare feed intake of fast-growing, high-yield broilers that differ in motor ability when fed diets with and without the analgesic drug carprofen.
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
Primary Audience: Behaviorists, Breeders, Production Managers, Veterinarians
JAPR: Research Report
250
MATERIALS AND METHODS Experiment 1
Experiment 2 The experimental protocol for this experiment was based on the results from experiment 1. Added to the main effects in experiment 1 were individuals with gait scores of 2, 3, and 4 [23]. The objective was to compare %ADFI among broilers with intermediate gait scores. Thus, of the 36 males and 36 females selected,
RESULTS AND DISCUSSION Experiment 1 A significant difference was observed in %ADFI among carprofen doses. The %ADFI for the 0-mg dose (1.97 ± 0.07) was intermediate and was not different from the 34.3 mg/kg of feed (2.11 ± 0.07) and the 102.9 mg/kg of feed (1.88 ± 0.07), which differed. Sex × laterality was the only significant interaction. This interaction occurred because although females had no left-right preference in %ADFI (2.00 ± 0.08 for left vs. 1.96 ± 0.07 for right), males had a significant preference for the left compared with the right feeder (2.25 ± 0.07 vs. 1.73 ± 0.07). Experiment 2 Analysis of variance of %ADFI for this experiment is presented in Table 1. None of the 14 higher order interactions and only 1 (sex × laterality) of the 10 first-order interactions was significant. The interaction was because although males showed no left-right preference (3.90 ± 0.15 for left vs. 4.14 ± 0.21 for right), females had a significant preference for the left compared with the right feeder (3.97 ± 0.13 vs. 3.52 ± 0.14). Means and SE for the other main effects (day, gait score, and carprofen dose) are summarized in Table 2. Fluctuation was observed among days, with %ADFI being less for d 3 than for d 2 and 4, which did not differ. For gait score, a trend was observed, with higher values for score 2 than 4 and the values for 3 being intermediate. Because intake was expressed relative to BW, those broilers with the lower gait score had a higher relative food intake. No differences were observed in %ADFI among carprofen dosages. We can conclude, based on the lack of a carprofen dose × gait score interaction, that
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
This experiment was designed to ascertain if training was necessary for broilers to discriminate among varying dosages of the nonsteroidal anti-inflammatory drug carprofen [22] in their feed. The main effects were dosage of carprofen (0, 34.3, or 102.9 mg/kg of feed), sex (male, female), and laterality (left, right). At 35 d of age, broilers from a large sex-intermingled flock reared on wood shavings, with feed and water available ad libitum, were individually weighed and gait scored (scores from 1 to 5) [23]. The scores used were a slight modification [9] of those described by Kestin et al. [3]. From broilers with a score of 3, we randomly selected 36 males and 36 females for transfer to preassigned individual cages [24]. Each cage was equipped with 2 feeders that contained feed at all times. The assignment of carprofen dosages was at random in a manner such that all combinations were available. To balance for laterality, the feed with the lowest dosage was on the left side for half the cages and on the right side for the other half. The basal diet [25] was a broiler finisher in pellet form. Carprofen [14, 22] at each dosage was mixed with 100 mL of distilled water and sprayed on the feed. For the 0-mg level, only 100 mL of water was sprayed on the feed. Feed consumption from each feeder was recorded daily on d 36, 37, and 38 (considered the training period). Individual BW were obtained again on d 39 and 43, with ADFI recorded for d 39 to 43. Because of variations in BW among individuals, the trait analyzed was ADFI corrected for BW (%ADFI). Data were analyzed using a split-plot design [26], with significance considered at P < 0.05.
12 males and 12 females had gait scores of 2, 3, or 4. Consistent with experiment 1, broilers at 35 d of age were weighed, gait scored, and transferred to preassigned cages. Their %ADFI was measured for d 37, 38, and 39 (i.e., d 2, 3, and 4 after caging). Data were analyzed using a split-plot design [26], with significance considered at P < 0.05.
Siegel et al.: MOTOR ABILITY OF BROILERS Table 1. Analysis of variance for %ADFI,1 experiment 2 df
Mean squares × 10−4
Sex (S) Gait (G) Feed type (FT) Day (D) Laterality (L) S×G S × FT S×D S×L G × FT G×D G×L FT × D FT × L D×L S × G × FT S×F×D S×D×L S×G×D S×G×L G × FT × D G × FT × L FT × D × L S × G × FT × D S × G × FT × L S×G×D×L S × FT × D × L G × FT × D × L S × G × FT × D × L
1 2 2 2 1 2 2 2 1 4 4 2 4 2 2 4 4 2 4 2 8 4 4 8 6 8 4 8 8
1.14 11.19** 0.05 11.14** 0.81 1.38 5.34 2.34 12.37** 1.13 0.76 1.61 1.74 2.01 2.89 0.81 0.73 5.36 0.15 1.73 1.06 3.67 1.37 1.72 1.82 2.59 0.22 1.73 1.88
1
%ADFI = ADFI corrected for BW. Sex (male, female), gait (score 2, 3, 4), feed type (carprofen dose of 0, 34.3, 102.9), day (2, 3, 4), and laterality (left, right). **P < 0.01. 2
among these treatment groups, no self-selection occurred for the feed containing the nonsteroidal anti-inflammatory analgesic.
Table 2. Means and SE for %ADFI1 by day, gait, and carprofen dose Item Day1 2 3 4 Gait score2 2 3 4 Carprofen dose, mg/kg of feed 0 34.3 102.9
4.05 ± 0.13a 3.56 ± 0.09b 4.04 ± 0.12a 4.17 ± 0.12a 3.86 ± 0.11ab 3.61 ± 0.12b 3.91 ± 0.13a 3.90 ± 0.11a 3.84 ± 0.12a
a,b
Means within a treatment with the same superscript are not different (P < 0.05). 1 %ADFI = ADFI corrected for BW. %ADFI was measured on d 2, 3, and 4 after caging. 2 See [23] for detailed descriptions.
population studied, individuals with intermediate gait scores did not exhibit a preference for a veterinary compound routinely prescribed for animals with joint pain. Although these results may appear inconsistent with results in which this was observed [12, 14, 17], it may be due in part to the testing procedures (traverse an obstacle course [12], feed color [14], vertical force [17]), underlying pathology, differences in activity levels of the broilers, or a combination of these factors, which could have altered the need to self-select the analgesic because of pain.
CONCLUSIONS AND APPLICATIONS
General We suggest, based on the lack of a preference among diets for chickens with gait scores of 2, 3, or 4, that although their motor ability may have been considered phenotypically compromised, it was not sufficient to elicit a preference for diets containing carprofen at these levels. Moreover, we did not measure a progression of gait scores over time. Pain is a vague term that is defined as “a state of physical or mental lack of well-being or physical or mental uneasiness that ranges from mild discomfort or dull distress to acute, often unbearable agony” [27]. For the
Mean ± SE
1. Individual broilers differed in their motor ability. Those with gait scores of 2, 3, and 4 did not exhibit a preference for an analgesic at the dosages used, suggesting that although abnormalities may have been identified, they were not sufficient for those chickens to prefer a diet containing an analgesic compound. 2. When given choices among diets, chickens exhibited laterality in dietary selection. The direction (left vs. right) was not necessarily predictable. Thus, laterality should be included in the experimental design of choice-feeding experiments. 3. Because no differences were observed among the intermediate gait scores, con-
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
Source of variation2
251
JAPR: Research Report
252 sideration should be given to reducing the classifications used in measuring the motor ability of meat-type poultry.
REFERENCES AND NOTES
Downloaded from http://japr.oxfordjournals.org/ at Georgian Court University on April 6, 2015
1. Havenstein, G. B., P. R. Ferket, and M. A. Qureshi. 2003. Growth, liveability, and feed conversion of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poult. Sci. 82:1500–1508. 2. Emmerson, D. A., N. B. Anthony, K. E. Nester, and Y. M. Saif. 1991. Genetic association of selection for increased leg muscle and increased shank diameter with body composition and walking ability. Poult. Sci. 70:739–745. 3. Kestin, S. C., T. G. Knowles, A. E. Tinch, and N. G. Gregory. 1992. Prevalence of leg weakness in broiler chickens and its relationship with genotype. Vet. Rec. 131:190– 194. 4. Skinner-Noble, D. O., and R. G. Teeter. 2009. An examination of anatomic, physiologic, and metabolic factors associated with well-being of broilers differing in field gait score. Poult. Sci. 88:2–9. 5. Weeks, C. A., T. D. Danbury, H. C. Davies, P. Hunt, and S. C. Kestin. 2000. The behavior of broiler chickens and its modification by lameness. Appl. Anim. Behav. Sci. 67:111–125. 6. Sørensen, P., G. Su, and S. C. Kestin. 2000. Effects of age and stocking density on leg weakness in broiler chickens. Poult. Sci. 79:864–870. 7. Su, G., P. Sorenson, and S. C. Kestin. 1999. Meal feeding is more effective than early feed restriction at reducing the prevalence of leg weakness in broiler chickens. Poult. Sci. 78:949–955. 8. Sanotra, G. S., L. G. Lawson, and K. S. Vertergaard. 2001. Influence of stocking density on tonic immobility, lameness and tibial dyschondroplasia in broilers. J. Appl. Anim. Welf. Sci. 12:677–683. 9. Garner, J. P., C. Falcone, P. Wakenell, M. Martin, and J. A. Mench. 2002. Reliability and validity of a modified gait scoring system and its use in accessing tibial dyschondroplasia in broilers. Br. Poult. Sci. 43:355–363. 10. Blatchford, R. A., K. C. Klasing, H. L. Shivaprusad, P. S. Wakenell, G. S. Archer, and J. A. Mench. 2009. The effect of light intensity on the behavior, eye and leg health, and immune function of broiler chickens. Poult. Sci. 88:20–28. 11. Weary, D. M., L. Niel, C. F. Flower, and D. Fraser. 2006. Identifying and preventing pain in animals. Appl. Anim. Behav. Sci. 100:64–76. 12. McGeown, D., T. C. Danbury, A. E. Waterman-Pearson, and S. C. Kestin. 1999. Effect of carprofen on lameness in broiler chickens. Vet. Rec. 144:668–671. 13. Hocking, P. M., R. Bernard, and M. H. Maxwell. 1999. Assessment of pain during locomotion and the welfare of adult male turkeys with destructive cartilage loss of the hip joint. Br. Poult. Sci. 40:30–34.
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