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Effect of Different Levels of Dietary Sorbic Acid on General Performance and Incidence of Leg Abnormalities of Commercial Broilers Reared to Roaster Weight1
Effect of Different Levels of Dietary Sorbic Acid on General Performance and Incidence of Leg Abnormalities of Commercial Broilers Reared to Roaster Weight1 H. W. HULAN and F. G. PROUDFOOT Research Station, Agriculture Canada, Kentville, Nova Scotia, Canada B4N 1J5
ABSTRACT Two thousand male, day-old Hubbard chicks were housed in 20 pens (13.5 m 2 ) to evaluate the effects on performance and leg abnormalities of feeding 0, 200, 400, and 600 g/ton dietary sorbic acid during the starter, grower, and finisher periods. These levels of dietary sorbic acid had no significant effect on live body weight, feed conversion, mortality, or the incidence of leg abnormalities of these chicken broilers reared to roaster weight. (Key words: sorbic acid, roasters, leg abnormalities) 1984 Poultry Science 63:1800-1802 INTRODUCTION
Although the commercial rearing of broiler genotypes to marketable roaster weight (3.2 kg) is a comparatively new farm enterprise, the production and consumer demand for such a bird continues to increase. A major factor preventing the roaster industry from reaching its full potential is the high incidence of mortality resulting primarily from leg weakness problems. Studies conducted in this laboratory over the last 5 years have demonstrated that the incidence of mortality and leg weakness differs among commercial broiler genotypes reared to roaster weight and that the incidence of leg abnormalities appears to be related to the rate of growth andlevel of dietary protein (Hulan et al., 19jOJ^More recently, Hulan and Proudfoot (1981) reported on the development of a low protein_jiietary regimen suitable for the commercial production oTToasters that reduces'the incidence of mortality alid_visual leg abnormalities from the_usual 12 to 14%_to 2.5 to 5.5%. Subsequently, it was demonstrated that this low protein dietary regimen is not genotype specific (Hulan et al, 1982) and that dietary energy per se has little effect on the incidence of mortality and leg abnormalities of broiler genotypes reared to roaster weight (Hulan and Proudfoot, 1982). Although the development of the low protein regimen has led to a substantial and
1
Contribution No. 1809.
significant reduction in mortality and incidence of leg abnormalities assessed on a visual basis (Hulan and Proudfoot, 1981), a more detailed postmortem examination indicated that the incidence of specific leg abnormalities in roasters remains high (Hulan and Proudfoot, 1982). Harri&_gf al. (1980^ reported that the addition of .04% of a special form of dietary sorbic acid~to the diet reduced the incidence of twisted leg from 19.9 to 9.9% for broilers grown on new litter and from^5^2 to 10.2% for those grown on built-up litter. They also reported. _..th.at.__spraying built-up litter with potassium sorbate significantly reduced the incidence of twisted leg from 20.8 to 11.6% but that a combinations? dietary sorbic acid and litter_ sj)ray_„.„sjiowecl_ no additional benefit over either treatment^ used alone. They concluded that the addition of sorbic acid to the diet or treatment of litter with potassium sorbate was effective in reducing the incidence of leg problems in broilers. In view of this conclusion, it was decided to investigate the effect of different levels of dietary sorbic acid on the general performance and incidence of leg abnoramlities of commercial broilers reared to roaster weight on new litter.
MATERIALS AND METHODS
A total of 2000 male day-old Hubbard chicks were randomized into 20 pens (100 per pen), each with a floor area of 13.54 m 2 (146 ft 2 ). Four cylindrical-type feeders and one bell-shaped waterer were provided in each pen.
1800
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
(Received for publication December 1, 1983)
SORBIC ACID AND LEG ABNORMALITIES IN ROASTERS
killed were included in the mortality data. After slaughter, 125 birds from each dietary regimen were returned to the laboratory with feet and legs intact. The condition of the leg bones and joints was determined by examining closely the tarsometatarsus, then opening and sagittally cutting both joints of the tibiotarsus and femur, and by removing the muscle tissue from the tibiotarsus and femur and carefully examining the bones. An analysis of variance (Snedecor and Cochran, 1980) was conducted on pen means. Percent mortality was transformed to angles for the analysis. RESULTS AND DISCUSSION Because there were no significant treatment effects on mortality, live body weights, or feed conversion observed at 21 or 49 days, only the final results (70 days) are presented in Table 1. As indicated (Table 1), feeding of up to 600 g/ton of dietary sorbic acid had no significant effect on live body weights of the roaster chicken. This observation is in agreement with that of Suwathep et al. (1981), who found no significant difference in the body weight of broilers fed diets containing 250 g/ton sorbic acid compared with broilers fed a control diet containing no sorbic acid. The body weight response observed in this study is contrary to the observations of Dilworth et al. (1979), who reported a significant improvement in the growth rate of broiler chickens fed 400 g/ton sorbic acid compared to broiler chickens fed a diet without sorbic acid. Feeding of sorbic acid had no significant effect on feed conversion.
TABLE 1. Effect of feeding different levels of sorbic acid during the starter, grower, and finisher periods on general performance and incidence of leg abnormalities of roaster chicken at slaughter (70 days of age) Treatment/ (g/ton)
mortality 1
Final live weight (g)
0 200 400 600 SEM
17.3 15.1 17.6 15.8 1.58
3341 3423 3389 3348 32.2
1 2
Leg abnormalities 1 ' 2 conversion
TL
AJ
TD
Total
2.38 2.33 2.34 2.34 .020
24.1 25.6 25.9 24.5 2.48
9.6 10.4 2.6 2.5 3.29
32.7 32.2 29.3 32.3 2.84
56.2 62.8 57.9 53.9 3.72
Arc sin angle.
TL = Twisted leg; AJ = arthritic joint; TD = tibial dyschondroplasia; Total = total leg abnormalities, including slipped tendons, twisted legs, hemorrhagic joints, arthritic joints, enlarged hocks, tibial dyschondroplasia, erosion of femoral head, and femoral head necrosis.
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
Initial hover temperature was set at 35 C and reduced 3 C per week until a temperature of 23 C was obtained. All stock were started on continuous lighting with a light intensity of 30 lx, which was gradually reduced so that at 21 days the birds were receiving a light intensity of 5 lx from incandescent bulbs. The 24-hr daylength was continued throughout the experiment. The low protein dietary regimen developed previously for roasters (Hulan and Proudfoot, 1981) was used. Percent protein and kilocalories metabolizable energy per kilogram were, respectively, 16 and 3000 for starter, 20 and 3100 for grower, and 16 and 3200 for finisher diets. Sorbic acid (manufactured and sold by Monsanto Co. under the registered trademark "Aflaban") was incorporated into each starter, grower, and finisher diet via the vitamin-mineral premix at 0, 200, 400, or 600 g/ton. The four treatments were each assigned and fed to five pens of birds in a completely randomized design. Starters were fed as crumbles from 1 to 21 days of age, while growers and finishers were fed as pellets from 22 to 49 and from 50 to 70 days of age, respectively. Traits measured were percentage mortality and live weight at 21, 49, and 70 days. Feed consumption was recorded and feed conversion calculated as the unit weight of feed per unit live weight up to 21, 49, and 70 days. Postmortem examinations were performed on all birds that died; the cause of death and condition of the legs were determined. Furthermore, any bird unable to reach feed and water because of leg problems was killed and the condition of both legs determined. Birds so
1801
1802
HULAN AND PROUDFOOT body weights, mortality, feed conversion, or incidence of leg abnormalities. ACKNOWLEDGMENT To K. B. McRae for advice and assistance freely given on experimental design, statistical analyses, and for processing the data.
REFERENCES Arafa, A. S., R. D. Miles, R. H. Harms, T. C. Chen, B. C. Dilworth, E. J. Day, G. L. Romoser, V. G. DiFate, and K. J. Shaver, 1979. Fungistatic compounds in broiler production. 4. Microbiological and physical characteristics of litter. Poultry Sci. 58:1462-1468. Charles, O. W., and S. Duke, 1980. The response of broiler chicks to graded levels of Sorbic acid in combination with two coccidiostats. Poultry Sci. 59:1591. (Abstr.) Dilworth, B. C , T. C. Chen, E. J. Day, R. D. Miles, A. S. Arafa, R. H. Harms, G. L. Romoser, V. G. DiFate, and K. J. Shaver, 1979. Fungistatic compounds in broiler production. 1. Effect on rate of gain and feed utilization. Poultry Sci. 58:1445-1450. Harris, G. C , Jr., R. Sellers, J. Benson, M. Musbah, V. Scogin, and P. W. Waldroup, 1980. Influence of dietary sorbic acid and litter treatment with potassium sorbate on "twisted leg" problem of broilers. Poultry Sci. 59:1564. (Abstr.) Hulan, H. W., and F. G. Proudfoot, 1981. The effect of different dietary protein levels in a three stage diet system on general performance of chickens reared to roaster weight. Poultry Sci. 60:172— 178. Hulan, H. W., and F. G. Proudfoot, 1982. The effect of different dietary energy regimens on the performance of two commercial chicken broiler genotypes reared to roaster weight. Poultry Sci. 61:510-515. Hulan, H. W., F. G. Proudfoot, and D. Ramey, 1982. The performance of male broiler genotypes reared to roaster weight and females reared to broiler weight on a low protein dietary regimen. Poultry Sci. 61:434-437. Hulan, H. W., F. G. Proudfoot, D. Ramey, and K. B. McRae, 1980. Influence of genotype and diet on general performance and incidence of leg abnormalities of commercial broilers reared to roaster weight. Poultry Sci. 59:748-757. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 8th ed. Iowa State Press, Ames, IA. Suwathep, M., C. R. Parkhurst, and F. M. McCorkle, 1981. Efficacy of sorbic acid as a fungistatic compound in low and high moisture broiler diets. Poultry Sci. 60:1741-1742. (Abstr.)
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
This observation is in partial agreement with that of Charles and Duke (1980), who reported only a numerical improvement in feed conversion (utilization) of broiler chickens fed diets containing 200 or 800 g/ton sorbic acid compared with a control diet without sorbic acid. Dilworth et al. (1979) and Suwathep et al. (1981) reported a significant improvement in feed conversion when broiler chickens were fed 250 or 400 g/ton sorbic acid, respectively, compared with a control diet without sorbic acid. In the study reported here, mortality was not significantly affected by either level of dietary sorbic acid tested. The incidence of twisted legs was not significantly affected from feeding up to 600 g/ton sorbic acid to these roaster chickens. This observation is contrary to that of Harris et al. (1980), who reported that feeding a level of 400 g/ton sorbic acid to broiler chickens grown on new litter significantly reduced the incidence of "twisted leg" from 19.9 to 9.9% and from 25.2 to 10.2% in broilers grown on built-up litter. The incidence of arthritis infection of thehock joint appeared to be reduced (not statistically significant) by feeding the higher levels (400 or 600 g/ton) sorbic acid. Arthritis infection of the hock joint is associated in the field with damp and/or wet litter conditions. Interestingly, Arafa et al. (1979) reported that feeding 400 g/ton sorbic acid resulted in dryer litter with better physical conditions. They, however, did not report what effect, if any, such treatment had on leg problems in general and more specifically what effect the treatment had on arthritis infection of the hock joint. The incidence of tibial dyschondroplasia was not significantly affected by addition of sorbic acid fed nor was the incidence of total leg abnormalities affected by dietary treatment. There were no significant trends in the incidence of hemorrhagic joint, enlarged hocks, erosion of femoral head, femoral head necrosis, or slipped tendons among dietary treatments. To conclude, the inclusion of 0, 200, 400, or 600 g/ton sorbic acid in the starter, grower, and finisher diets fed to broiler chickens reared to roaster weight, had no significant effect on live
ABSTRACT Two thousand male, day-old Hubbard chicks were housed in 20 pens (13.5 m 2 ) to evaluate the effects on performance and leg abnormalities of feeding 0, 200, 400, and 600 g/ton dietary sorbic acid during the starter, grower, and finisher periods. These levels of dietary sorbic acid had no significant effect on live body weight, feed conversion, mortality, or the incidence of leg abnormalities of these chicken broilers reared to roaster weight. (Key words: sorbic acid, roasters, leg abnormalities) 1984 Poultry Science 63:1800-1802 INTRODUCTION
Although the commercial rearing of broiler genotypes to marketable roaster weight (3.2 kg) is a comparatively new farm enterprise, the production and consumer demand for such a bird continues to increase. A major factor preventing the roaster industry from reaching its full potential is the high incidence of mortality resulting primarily from leg weakness problems. Studies conducted in this laboratory over the last 5 years have demonstrated that the incidence of mortality and leg weakness differs among commercial broiler genotypes reared to roaster weight and that the incidence of leg abnormalities appears to be related to the rate of growth andlevel of dietary protein (Hulan et al., 19jOJ^More recently, Hulan and Proudfoot (1981) reported on the development of a low protein_jiietary regimen suitable for the commercial production oTToasters that reduces'the incidence of mortality alid_visual leg abnormalities from the_usual 12 to 14%_to 2.5 to 5.5%. Subsequently, it was demonstrated that this low protein dietary regimen is not genotype specific (Hulan et al, 1982) and that dietary energy per se has little effect on the incidence of mortality and leg abnormalities of broiler genotypes reared to roaster weight (Hulan and Proudfoot, 1982). Although the development of the low protein regimen has led to a substantial and
1
Contribution No. 1809.
significant reduction in mortality and incidence of leg abnormalities assessed on a visual basis (Hulan and Proudfoot, 1981), a more detailed postmortem examination indicated that the incidence of specific leg abnormalities in roasters remains high (Hulan and Proudfoot, 1982). Harri&_gf al. (1980^ reported that the addition of .04% of a special form of dietary sorbic acid~to the diet reduced the incidence of twisted leg from 19.9 to 9.9% for broilers grown on new litter and from^5^2 to 10.2% for those grown on built-up litter. They also reported. _..th.at.__spraying built-up litter with potassium sorbate significantly reduced the incidence of twisted leg from 20.8 to 11.6% but that a combinations? dietary sorbic acid and litter_ sj)ray_„.„sjiowecl_ no additional benefit over either treatment^ used alone. They concluded that the addition of sorbic acid to the diet or treatment of litter with potassium sorbate was effective in reducing the incidence of leg problems in broilers. In view of this conclusion, it was decided to investigate the effect of different levels of dietary sorbic acid on the general performance and incidence of leg abnoramlities of commercial broilers reared to roaster weight on new litter.
MATERIALS AND METHODS
A total of 2000 male day-old Hubbard chicks were randomized into 20 pens (100 per pen), each with a floor area of 13.54 m 2 (146 ft 2 ). Four cylindrical-type feeders and one bell-shaped waterer were provided in each pen.
1800
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
(Received for publication December 1, 1983)
SORBIC ACID AND LEG ABNORMALITIES IN ROASTERS
killed were included in the mortality data. After slaughter, 125 birds from each dietary regimen were returned to the laboratory with feet and legs intact. The condition of the leg bones and joints was determined by examining closely the tarsometatarsus, then opening and sagittally cutting both joints of the tibiotarsus and femur, and by removing the muscle tissue from the tibiotarsus and femur and carefully examining the bones. An analysis of variance (Snedecor and Cochran, 1980) was conducted on pen means. Percent mortality was transformed to angles for the analysis. RESULTS AND DISCUSSION Because there were no significant treatment effects on mortality, live body weights, or feed conversion observed at 21 or 49 days, only the final results (70 days) are presented in Table 1. As indicated (Table 1), feeding of up to 600 g/ton of dietary sorbic acid had no significant effect on live body weights of the roaster chicken. This observation is in agreement with that of Suwathep et al. (1981), who found no significant difference in the body weight of broilers fed diets containing 250 g/ton sorbic acid compared with broilers fed a control diet containing no sorbic acid. The body weight response observed in this study is contrary to the observations of Dilworth et al. (1979), who reported a significant improvement in the growth rate of broiler chickens fed 400 g/ton sorbic acid compared to broiler chickens fed a diet without sorbic acid. Feeding of sorbic acid had no significant effect on feed conversion.
TABLE 1. Effect of feeding different levels of sorbic acid during the starter, grower, and finisher periods on general performance and incidence of leg abnormalities of roaster chicken at slaughter (70 days of age) Treatment/ (g/ton)
mortality 1
Final live weight (g)
0 200 400 600 SEM
17.3 15.1 17.6 15.8 1.58
3341 3423 3389 3348 32.2
1 2
Leg abnormalities 1 ' 2 conversion
TL
AJ
TD
Total
2.38 2.33 2.34 2.34 .020
24.1 25.6 25.9 24.5 2.48
9.6 10.4 2.6 2.5 3.29
32.7 32.2 29.3 32.3 2.84
56.2 62.8 57.9 53.9 3.72
Arc sin angle.
TL = Twisted leg; AJ = arthritic joint; TD = tibial dyschondroplasia; Total = total leg abnormalities, including slipped tendons, twisted legs, hemorrhagic joints, arthritic joints, enlarged hocks, tibial dyschondroplasia, erosion of femoral head, and femoral head necrosis.
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
Initial hover temperature was set at 35 C and reduced 3 C per week until a temperature of 23 C was obtained. All stock were started on continuous lighting with a light intensity of 30 lx, which was gradually reduced so that at 21 days the birds were receiving a light intensity of 5 lx from incandescent bulbs. The 24-hr daylength was continued throughout the experiment. The low protein dietary regimen developed previously for roasters (Hulan and Proudfoot, 1981) was used. Percent protein and kilocalories metabolizable energy per kilogram were, respectively, 16 and 3000 for starter, 20 and 3100 for grower, and 16 and 3200 for finisher diets. Sorbic acid (manufactured and sold by Monsanto Co. under the registered trademark "Aflaban") was incorporated into each starter, grower, and finisher diet via the vitamin-mineral premix at 0, 200, 400, or 600 g/ton. The four treatments were each assigned and fed to five pens of birds in a completely randomized design. Starters were fed as crumbles from 1 to 21 days of age, while growers and finishers were fed as pellets from 22 to 49 and from 50 to 70 days of age, respectively. Traits measured were percentage mortality and live weight at 21, 49, and 70 days. Feed consumption was recorded and feed conversion calculated as the unit weight of feed per unit live weight up to 21, 49, and 70 days. Postmortem examinations were performed on all birds that died; the cause of death and condition of the legs were determined. Furthermore, any bird unable to reach feed and water because of leg problems was killed and the condition of both legs determined. Birds so
1801
1802
HULAN AND PROUDFOOT body weights, mortality, feed conversion, or incidence of leg abnormalities. ACKNOWLEDGMENT To K. B. McRae for advice and assistance freely given on experimental design, statistical analyses, and for processing the data.
REFERENCES Arafa, A. S., R. D. Miles, R. H. Harms, T. C. Chen, B. C. Dilworth, E. J. Day, G. L. Romoser, V. G. DiFate, and K. J. Shaver, 1979. Fungistatic compounds in broiler production. 4. Microbiological and physical characteristics of litter. Poultry Sci. 58:1462-1468. Charles, O. W., and S. Duke, 1980. The response of broiler chicks to graded levels of Sorbic acid in combination with two coccidiostats. Poultry Sci. 59:1591. (Abstr.) Dilworth, B. C , T. C. Chen, E. J. Day, R. D. Miles, A. S. Arafa, R. H. Harms, G. L. Romoser, V. G. DiFate, and K. J. Shaver, 1979. Fungistatic compounds in broiler production. 1. Effect on rate of gain and feed utilization. Poultry Sci. 58:1445-1450. Harris, G. C , Jr., R. Sellers, J. Benson, M. Musbah, V. Scogin, and P. W. Waldroup, 1980. Influence of dietary sorbic acid and litter treatment with potassium sorbate on "twisted leg" problem of broilers. Poultry Sci. 59:1564. (Abstr.) Hulan, H. W., and F. G. Proudfoot, 1981. The effect of different dietary protein levels in a three stage diet system on general performance of chickens reared to roaster weight. Poultry Sci. 60:172— 178. Hulan, H. W., and F. G. Proudfoot, 1982. The effect of different dietary energy regimens on the performance of two commercial chicken broiler genotypes reared to roaster weight. Poultry Sci. 61:510-515. Hulan, H. W., F. G. Proudfoot, and D. Ramey, 1982. The performance of male broiler genotypes reared to roaster weight and females reared to broiler weight on a low protein dietary regimen. Poultry Sci. 61:434-437. Hulan, H. W., F. G. Proudfoot, D. Ramey, and K. B. McRae, 1980. Influence of genotype and diet on general performance and incidence of leg abnormalities of commercial broilers reared to roaster weight. Poultry Sci. 59:748-757. Snedecor, G. W., and W. G. Cochran, 1980. Statistical Methods. 8th ed. Iowa State Press, Ames, IA. Suwathep, M., C. R. Parkhurst, and F. M. McCorkle, 1981. Efficacy of sorbic acid as a fungistatic compound in low and high moisture broiler diets. Poultry Sci. 60:1741-1742. (Abstr.)
Downloaded from http://ps.oxfordjournals.org/ at National Institute of Education Library, Serials Unit on April 24, 2015
This observation is in partial agreement with that of Charles and Duke (1980), who reported only a numerical improvement in feed conversion (utilization) of broiler chickens fed diets containing 200 or 800 g/ton sorbic acid compared with a control diet without sorbic acid. Dilworth et al. (1979) and Suwathep et al. (1981) reported a significant improvement in feed conversion when broiler chickens were fed 250 or 400 g/ton sorbic acid, respectively, compared with a control diet without sorbic acid. In the study reported here, mortality was not significantly affected by either level of dietary sorbic acid tested. The incidence of twisted legs was not significantly affected from feeding up to 600 g/ton sorbic acid to these roaster chickens. This observation is contrary to that of Harris et al. (1980), who reported that feeding a level of 400 g/ton sorbic acid to broiler chickens grown on new litter significantly reduced the incidence of "twisted leg" from 19.9 to 9.9% and from 25.2 to 10.2% in broilers grown on built-up litter. The incidence of arthritis infection of thehock joint appeared to be reduced (not statistically significant) by feeding the higher levels (400 or 600 g/ton) sorbic acid. Arthritis infection of the hock joint is associated in the field with damp and/or wet litter conditions. Interestingly, Arafa et al. (1979) reported that feeding 400 g/ton sorbic acid resulted in dryer litter with better physical conditions. They, however, did not report what effect, if any, such treatment had on leg problems in general and more specifically what effect the treatment had on arthritis infection of the hock joint. The incidence of tibial dyschondroplasia was not significantly affected by addition of sorbic acid fed nor was the incidence of total leg abnormalities affected by dietary treatment. There were no significant trends in the incidence of hemorrhagic joint, enlarged hocks, erosion of femoral head, femoral head necrosis, or slipped tendons among dietary treatments. To conclude, the inclusion of 0, 200, 400, or 600 g/ton sorbic acid in the starter, grower, and finisher diets fed to broiler chickens reared to roaster weight, had no significant effect on live