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Infected Feather Follicles in Cage Reared Broilers1
1194
G . ROGERSON AND E . P . SlNGSEN
magnesium administration. Invest. Urol. 2: 7-10. Prien, E. L., 1949. Studies in urolithiasis: II Relationships between pathogenesis, structure and composition of calculi. J. Urol. 61: 821-836. Rimland, B., 1973. High dosage levels of certain vitamins in the treatment of children with severe mental disorder. In: Orthomolecular Psychiatry— Treatment of Schizophrenia, edited by D. Hawkins and L. Pauling, W. H. Freeman &Co., San Francisco. pg. 522. Rinehart, K. E., W. R. Featherston and J. C. Rogler, 1969. Influence of dietary potassium on chick growth, food consumption and blood and tissue composition. Poultry Sci. 48: 320-325. Rogerson, G., and E. P. Singsen, 1976. Effects of magnesium and high dietary intakes of pyridoxine on the chick. Poultry Sci. Snedecor, G. W., and W. H. Cochran, 1971. Statistical Methods, The Iowa State University Press, Ames, Iowa, pp. 271-273 and 381-418. Snell, E. E., and S. J. Dimari, 1970. Schiff base intermediates in enzyme catalysis. In: The Enzymes, VII, edited by P. D. Boyer, Academic Press, New York, pp. 335-370.
Infected Feather Follicles in Cage Reared Broilersl R. C. BAYER, F . V. M U I R , C. B . CHAWAN AND T. A. BRYAN
Department of Animal and Veterinary Sciences, University of Maine, Orono, Maine 04473 (Received for publication August 7. 1975)
ABSTRACT A high incidence of feather follicle infection was observed in broilers reared in cages with wood slat floors. The incidence of feather follicle infection was significantly higher for males than for females within cage-reared broilers at 59 days of age. Male broilers at 50 days of age had a significantly lower incidence of the feather follicle condition than hatch mates at 59 days of age. Intact feather follicles were removed from freshly killed cage-reared birds and prepared for scanning electron microscopy (SEM). Examination of infected follicles revealed surface detail about the lesions. Removal of the encrustations covering the infected follicles revealed numerous cocci type bacteria at the base of the follicle. Infected and non-infected follicles were also examined by conventional histological techniques. Gram positive cocci were observed at the base of the infected follicles. POULTRY SCIENCE 55: 1194-1200, 1976
INTRODUCTION
A
CONSIDERABLE amount of labor could be saved by rearing broilers in cages which could be moved directly to
1. Presented in part at the 63rd annual meeting of the Poultry Science Association.
processing plants. Such "grow-trans" cages have been developed for broiler rearing (Muir et ai, 1970; Lloyd et ai, 1970). A problem that developed in cage-reared birds was feather follicle infection and inflammation (Lloyd, 1971; Lloyd et al., 1971; Andrews et ai, 1975). The present study was designed to investigate the influence of age at process-
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
activities of pyridoxine-deficient male rats. J. Nutr. 65: 547-559. Hochberg, M., D. Melnick and B. L. Oser, 1944. Chemical determination of pyridoxine in biological materials and pharmaceutical products. The multiple nature of vitamin B-6. J. Biol. Chem. 155: 119-128. Hsu, J. M., R. L. Davis and B. F. Chow, 1958. Electrolyte imbalance in vitamin B-6 deficient rats. J. Biol. Chem. 230: 889-895. Krebs, E. G., and E. H. Fischer, 1964. Phosphorylase and related enzymes of glycogen metabolism. Vitamins and Hormones, 22: 399-410. Lehninger, A. L., 1970. Biochemistry, the Molecular Basis of Cell Structure and Function, Worth Publishers, Inc., N.Y. pg. 329. Lyon, J. B., Jr., J. A. Bain and H. L. Williams, 1962. The distribution of vitamin B-6 in the tissues of two inbred strains of mice fed complete and vitamin B-6 deficient rations. J. Biol. Chem. 237: 1989-1991. McCormick, D. B., M. E. Gregory and E. E. Snell, 1961. Pyridoxal phosphokinases, I: Assay, distribution, purification and properties. J. Biol. Chem. 236: 2076-2084. Moore, C. A., and G. E. Bunce, 1964. Reduction in frequency of renal calculus formation by oral
INFECTED FEATHER FOLLICLES
ing on the feather follicle problems and to describe the feather follicle lesion with light and scanning electron microscopy. PROCEDURE
RESULTS The incidence of swollen feather follicle and average body weight as influenced by growing environment and processing age are presented in Table 1. Preliminary analysis of the data indicated no strain influence associated with the incidence of swollen feather follicles, therefore the data from the two strains were combined. Lloyd era/. (1971) and Andrews et al. (1975) reported a strain effect on the incidence of swollen feather follicles. It can be seen from Table 1 that the feather follicle problem was characteristic of cage-grown broilers and not of floor-reared broilers. Considering the cage-reared birds, there was a significant sex influence on incidence of swollen feather follicles at 59 days of age. Average body weight of the floorreared broilers was significantly greater than cage-reared birds at 50 days of age. This was true for both sexes. There was no significant rearing environment influence on body weight of the birds processed at 59 days of age. A normal feather follicle with intact feather is shown in Figure 1. The infected feather follicle has an encrusted lamellar surface as seen in Figure 2. There is no feather protruding from the infected follicle. Removal of the encrustation from the infected follicle reveals crater-like appearance of the follicle (Figure 3). Figure 4 shows the base of an infected follicle at a higher magnification showing a dense population of coccoid parti-
TABLE 1.—Incidence of swollen feather follicles and average body weight as influenced by growing environment and processing age Processing age 50 days Males Females 59 days Males Females
Swollen feather follicles (%) Floor Cages'
Body weight 2 Cages
Floor
33.3a 20.0a
0.0 0.0
1749.6a 1381.8a
1878.3b 1602.8b
68.8a 23.1b
0.0 0.0
2233.3a 1850.7a
2272.1a 1866.1a
1. Means within processing age with different letters are significantly different, (p < 0.05). 2. Body weight within sexes at 50 and 59 days with different letters are significantly different. (p < 0.05).
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
Hubard x Hubbard and Cobb x Cobb chicks were reared in a battery brooder until they were 14 days old. At two weeks of age one group of birds was transferred to growtrans cages with wood slatted floors. An additional group of chickens was reared in a floor pen as a control. The birds were reared to 50 or 59 days of age at which time they were processed by commercial broiler processor and the incidence of feather follicle infection was examined. An additional experiment was conducted to study the characteristics of the infected follicles. Birds were reared in grow-trans cages until feather follicles became infected. Birds with infected feather follicles and control birds with normal feather follicles were sacrificed. Infected and uninfected follicles were prepared for conventional histology. Paraffin sections were cut to 6 (x. thickness and stained with hematoxylin and eosin or with a gram stain. Infected and uninfected follicles were also fixed in glutaraldehyde, post-fixed in osmium tetroxide, vacuum dried using the procedure of Bayer et al. (1974), mounted on aluminum stubs and examined with a Cambridge Stereoscan S-4 scanning electron microscope.
1195
1196
R. C. BAYER, F. V.
MUIR, C.
B. CHAWAN AND T.
A.
BRYAN
i, FIG. 1. Scanning electron micrograph of normal intact feather follicle with protruding feather indicated with arrows. The line represents 111.1 microns.
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
r^y ^
INFECTED FEATHER FOLLICLES
1197
cles. A gram-positive reaction was observed with the cocci when conventional histology and a gram stain was used. DISCUSSION There was a more pronounced incidence of swollen or infected feather follicles in male broilers than in the female broilers. This incidence of swollen feather follicles could be the result of either an increase in the age of the broilers, increased body weight or a combination of these two factors. The inflammation resulting in swollen follicles is probably associated with the grampositive cocci bacteria seen with SEM and
light microscopy to be lining the infected follicles. These bacteria are harbored readily on the rough porous boards that made up the flooring of the grow-trans cages tested. With increasing age and the associated weight, the bird's breast has increased contact with the floor allowing irritation of the tissue and innoculation with bacteria. The strains of birds studied were similar in size and weight making them equally susceptible to breast irritation and associated feather follicle infection. A softer floor causes a much lower incidence of feather follicle problems (Lloyd et al., 1970). There is probably less irritation to breast tissues with the softer material.
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 2. Scanning electron micrograph of encrustation on infected feather follicle. The line represents 500 microns.
1198
R. C.
BAYER, F . V.
Mum,
C. B . CHAWAN AND T. A.
BRYAN
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 3. Scanning electron micrograph of infected feather follicle with encrustation removed. The line represents 454.6 microns.
INFECTED FEATHER FOLLICLES
1199
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 4. Scanning electron micrograph of cocci at the base of infected follicle. Line represents 1.8 microns.
1200
R.
C.
BAYER, F . V.
Mum,
C. B . CHAWAN AND T.
REFERENCES Andrews, L. D., G. S. Nelson, G. C. Harris, Jr. and T. L. Goodwin, 1975. Performance of five strains of broilers in a four-tier cage system with plastic mat floors. Poultry Sci. 54: 54-58. Bayer, R. C , F. H. Bird, S. D. Musgrave and C. B. Chawan, 1974. A simple method of preparation of gastrointestinal tract tissues for scanning electron microscopy. J. Ani. Sci. 38: 354-356. Lloyd, R. W., 1971. Incidence of feather follicle infection of broilers grown in plastic coops as influenced by breed or strain. Proc. Tenth Annual
A.
BRYAN
Broiler Housing Seminar, 10: 13-18. Lloyd, R. W., G. W. Chaloupka and W. C. Kraus, 1971. Incidence of feather follicle infection of broilers grown in plastic coops as influenced by breed or strain. Poultry Sci. 50: 1598. Lloyd, R. W., G. W. Chaloupka and E. W. Walpole, 1970. Plastic coop system of producing broilers. Poultry Sci. 49: 1407. Muir, F. V., H. C. Whelden and C. W. Kittridge, 1970-71. A gro-trans cage for broilers. Research in the Life Sciences, a Quarterly Report of the Maine Agricultural Experiment Station 18: 6-9.
P. V. TWINING, J R . , 2 O.
P. THOMAS AND E.
H.
BOSSARD
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication August 18, 1975)
ABSTRACT Two studies were conducted in floor pen facilities to evaluate broiler diets containing various protein and amino acid levels. In Study #1 at 48 and 56 and at 49 and 59 days of age in Study #2, the number of body and flight feathers onthe litter in two separate 0.37 sq. meter areas located in the same place in each pen was recorded. In Study #1 Hubbard x Hubbard broiler crosses were employed. There were very few body feathers on the litter at 48 or 56 days of age. At 56 days the birds that had been on a high protein finisher ration had significantly (P < 0.05) more unconsumed feathers on the floor than those birds which had received the low protein finisher diet. In Study #2 both Hubbard x Hubbard and Cobb x Cobb broiler crosses were used. The birds receiving the high protein diets consistantly had more feathers on the litter than those birds receiving the low protein diets. There were significantly (P < 0.01) more feathers on the litter in the pens containing the Cobb x Cobb birds as compared to the pens containing the Hubbard x Hubbard broiler crosses. POULTRY SCIENCE 55: 1200-1207, 1976
INTRODUCTION HE normal criteria for evaluating the adequacy of practical broiler diets with different nutrient levels are to measure the relative growth and feed efficiency between broilers receiving these diets. From time to time, other criteria such as NPU, biological value and digestibility are used. Gordon and Sizer (1955) also used degree of feathering as another criterion for evaluating the effects
T
1. Scientific Article No. A2139, Contribution No. 5103 of the Maryland Agricultural Experiment Station, Department of Poultry Science. 2. Present Address: Paul Twining Associates, Route 3, Box 354A, Princess Anne, Maryland 21853.
of adding sodium sulfate to the diet. They utilized a subjective scoring system of 0-4 to measure the degree of feathering in the birds. Combs (1956) also used feathering of the birds as an additional parameter for evaluating the effects of varying the C/P ratio on the performance of broilers during the starting and finishing periods. The birds were rated according to the percent of normally feathered birds within each treatment. In a study where the protein level of the diets was held constant and the energy level varied, Turk et al. (1961) observed that birds fed the two highest energy level diets were eating their feathers as fast as they were molted; whereas other pens were covered
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
The Number of Feathers on the Litter; Another Criterion for Evaluating the Adequacy of Broiler Diets'
G . ROGERSON AND E . P . SlNGSEN
magnesium administration. Invest. Urol. 2: 7-10. Prien, E. L., 1949. Studies in urolithiasis: II Relationships between pathogenesis, structure and composition of calculi. J. Urol. 61: 821-836. Rimland, B., 1973. High dosage levels of certain vitamins in the treatment of children with severe mental disorder. In: Orthomolecular Psychiatry— Treatment of Schizophrenia, edited by D. Hawkins and L. Pauling, W. H. Freeman &Co., San Francisco. pg. 522. Rinehart, K. E., W. R. Featherston and J. C. Rogler, 1969. Influence of dietary potassium on chick growth, food consumption and blood and tissue composition. Poultry Sci. 48: 320-325. Rogerson, G., and E. P. Singsen, 1976. Effects of magnesium and high dietary intakes of pyridoxine on the chick. Poultry Sci. Snedecor, G. W., and W. H. Cochran, 1971. Statistical Methods, The Iowa State University Press, Ames, Iowa, pp. 271-273 and 381-418. Snell, E. E., and S. J. Dimari, 1970. Schiff base intermediates in enzyme catalysis. In: The Enzymes, VII, edited by P. D. Boyer, Academic Press, New York, pp. 335-370.
Infected Feather Follicles in Cage Reared Broilersl R. C. BAYER, F . V. M U I R , C. B . CHAWAN AND T. A. BRYAN
Department of Animal and Veterinary Sciences, University of Maine, Orono, Maine 04473 (Received for publication August 7. 1975)
ABSTRACT A high incidence of feather follicle infection was observed in broilers reared in cages with wood slat floors. The incidence of feather follicle infection was significantly higher for males than for females within cage-reared broilers at 59 days of age. Male broilers at 50 days of age had a significantly lower incidence of the feather follicle condition than hatch mates at 59 days of age. Intact feather follicles were removed from freshly killed cage-reared birds and prepared for scanning electron microscopy (SEM). Examination of infected follicles revealed surface detail about the lesions. Removal of the encrustations covering the infected follicles revealed numerous cocci type bacteria at the base of the follicle. Infected and non-infected follicles were also examined by conventional histological techniques. Gram positive cocci were observed at the base of the infected follicles. POULTRY SCIENCE 55: 1194-1200, 1976
INTRODUCTION
A
CONSIDERABLE amount of labor could be saved by rearing broilers in cages which could be moved directly to
1. Presented in part at the 63rd annual meeting of the Poultry Science Association.
processing plants. Such "grow-trans" cages have been developed for broiler rearing (Muir et ai, 1970; Lloyd et ai, 1970). A problem that developed in cage-reared birds was feather follicle infection and inflammation (Lloyd, 1971; Lloyd et al., 1971; Andrews et ai, 1975). The present study was designed to investigate the influence of age at process-
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
activities of pyridoxine-deficient male rats. J. Nutr. 65: 547-559. Hochberg, M., D. Melnick and B. L. Oser, 1944. Chemical determination of pyridoxine in biological materials and pharmaceutical products. The multiple nature of vitamin B-6. J. Biol. Chem. 155: 119-128. Hsu, J. M., R. L. Davis and B. F. Chow, 1958. Electrolyte imbalance in vitamin B-6 deficient rats. J. Biol. Chem. 230: 889-895. Krebs, E. G., and E. H. Fischer, 1964. Phosphorylase and related enzymes of glycogen metabolism. Vitamins and Hormones, 22: 399-410. Lehninger, A. L., 1970. Biochemistry, the Molecular Basis of Cell Structure and Function, Worth Publishers, Inc., N.Y. pg. 329. Lyon, J. B., Jr., J. A. Bain and H. L. Williams, 1962. The distribution of vitamin B-6 in the tissues of two inbred strains of mice fed complete and vitamin B-6 deficient rations. J. Biol. Chem. 237: 1989-1991. McCormick, D. B., M. E. Gregory and E. E. Snell, 1961. Pyridoxal phosphokinases, I: Assay, distribution, purification and properties. J. Biol. Chem. 236: 2076-2084. Moore, C. A., and G. E. Bunce, 1964. Reduction in frequency of renal calculus formation by oral
INFECTED FEATHER FOLLICLES
ing on the feather follicle problems and to describe the feather follicle lesion with light and scanning electron microscopy. PROCEDURE
RESULTS The incidence of swollen feather follicle and average body weight as influenced by growing environment and processing age are presented in Table 1. Preliminary analysis of the data indicated no strain influence associated with the incidence of swollen feather follicles, therefore the data from the two strains were combined. Lloyd era/. (1971) and Andrews et al. (1975) reported a strain effect on the incidence of swollen feather follicles. It can be seen from Table 1 that the feather follicle problem was characteristic of cage-grown broilers and not of floor-reared broilers. Considering the cage-reared birds, there was a significant sex influence on incidence of swollen feather follicles at 59 days of age. Average body weight of the floorreared broilers was significantly greater than cage-reared birds at 50 days of age. This was true for both sexes. There was no significant rearing environment influence on body weight of the birds processed at 59 days of age. A normal feather follicle with intact feather is shown in Figure 1. The infected feather follicle has an encrusted lamellar surface as seen in Figure 2. There is no feather protruding from the infected follicle. Removal of the encrustation from the infected follicle reveals crater-like appearance of the follicle (Figure 3). Figure 4 shows the base of an infected follicle at a higher magnification showing a dense population of coccoid parti-
TABLE 1.—Incidence of swollen feather follicles and average body weight as influenced by growing environment and processing age Processing age 50 days Males Females 59 days Males Females
Swollen feather follicles (%) Floor Cages'
Body weight 2 Cages
Floor
33.3a 20.0a
0.0 0.0
1749.6a 1381.8a
1878.3b 1602.8b
68.8a 23.1b
0.0 0.0
2233.3a 1850.7a
2272.1a 1866.1a
1. Means within processing age with different letters are significantly different, (p < 0.05). 2. Body weight within sexes at 50 and 59 days with different letters are significantly different. (p < 0.05).
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
Hubard x Hubbard and Cobb x Cobb chicks were reared in a battery brooder until they were 14 days old. At two weeks of age one group of birds was transferred to growtrans cages with wood slatted floors. An additional group of chickens was reared in a floor pen as a control. The birds were reared to 50 or 59 days of age at which time they were processed by commercial broiler processor and the incidence of feather follicle infection was examined. An additional experiment was conducted to study the characteristics of the infected follicles. Birds were reared in grow-trans cages until feather follicles became infected. Birds with infected feather follicles and control birds with normal feather follicles were sacrificed. Infected and uninfected follicles were prepared for conventional histology. Paraffin sections were cut to 6 (x. thickness and stained with hematoxylin and eosin or with a gram stain. Infected and uninfected follicles were also fixed in glutaraldehyde, post-fixed in osmium tetroxide, vacuum dried using the procedure of Bayer et al. (1974), mounted on aluminum stubs and examined with a Cambridge Stereoscan S-4 scanning electron microscope.
1195
1196
R. C. BAYER, F. V.
MUIR, C.
B. CHAWAN AND T.
A.
BRYAN
i, FIG. 1. Scanning electron micrograph of normal intact feather follicle with protruding feather indicated with arrows. The line represents 111.1 microns.
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
r^y ^
INFECTED FEATHER FOLLICLES
1197
cles. A gram-positive reaction was observed with the cocci when conventional histology and a gram stain was used. DISCUSSION There was a more pronounced incidence of swollen or infected feather follicles in male broilers than in the female broilers. This incidence of swollen feather follicles could be the result of either an increase in the age of the broilers, increased body weight or a combination of these two factors. The inflammation resulting in swollen follicles is probably associated with the grampositive cocci bacteria seen with SEM and
light microscopy to be lining the infected follicles. These bacteria are harbored readily on the rough porous boards that made up the flooring of the grow-trans cages tested. With increasing age and the associated weight, the bird's breast has increased contact with the floor allowing irritation of the tissue and innoculation with bacteria. The strains of birds studied were similar in size and weight making them equally susceptible to breast irritation and associated feather follicle infection. A softer floor causes a much lower incidence of feather follicle problems (Lloyd et al., 1970). There is probably less irritation to breast tissues with the softer material.
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 2. Scanning electron micrograph of encrustation on infected feather follicle. The line represents 500 microns.
1198
R. C.
BAYER, F . V.
Mum,
C. B . CHAWAN AND T. A.
BRYAN
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 3. Scanning electron micrograph of infected feather follicle with encrustation removed. The line represents 454.6 microns.
INFECTED FEATHER FOLLICLES
1199
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
FIG. 4. Scanning electron micrograph of cocci at the base of infected follicle. Line represents 1.8 microns.
1200
R.
C.
BAYER, F . V.
Mum,
C. B . CHAWAN AND T.
REFERENCES Andrews, L. D., G. S. Nelson, G. C. Harris, Jr. and T. L. Goodwin, 1975. Performance of five strains of broilers in a four-tier cage system with plastic mat floors. Poultry Sci. 54: 54-58. Bayer, R. C , F. H. Bird, S. D. Musgrave and C. B. Chawan, 1974. A simple method of preparation of gastrointestinal tract tissues for scanning electron microscopy. J. Ani. Sci. 38: 354-356. Lloyd, R. W., 1971. Incidence of feather follicle infection of broilers grown in plastic coops as influenced by breed or strain. Proc. Tenth Annual
A.
BRYAN
Broiler Housing Seminar, 10: 13-18. Lloyd, R. W., G. W. Chaloupka and W. C. Kraus, 1971. Incidence of feather follicle infection of broilers grown in plastic coops as influenced by breed or strain. Poultry Sci. 50: 1598. Lloyd, R. W., G. W. Chaloupka and E. W. Walpole, 1970. Plastic coop system of producing broilers. Poultry Sci. 49: 1407. Muir, F. V., H. C. Whelden and C. W. Kittridge, 1970-71. A gro-trans cage for broilers. Research in the Life Sciences, a Quarterly Report of the Maine Agricultural Experiment Station 18: 6-9.
P. V. TWINING, J R . , 2 O.
P. THOMAS AND E.
H.
BOSSARD
Department of Poultry Science, University of Maryland, College Park, Maryland 20742 (Received for publication August 18, 1975)
ABSTRACT Two studies were conducted in floor pen facilities to evaluate broiler diets containing various protein and amino acid levels. In Study #1 at 48 and 56 and at 49 and 59 days of age in Study #2, the number of body and flight feathers onthe litter in two separate 0.37 sq. meter areas located in the same place in each pen was recorded. In Study #1 Hubbard x Hubbard broiler crosses were employed. There were very few body feathers on the litter at 48 or 56 days of age. At 56 days the birds that had been on a high protein finisher ration had significantly (P < 0.05) more unconsumed feathers on the floor than those birds which had received the low protein finisher diet. In Study #2 both Hubbard x Hubbard and Cobb x Cobb broiler crosses were used. The birds receiving the high protein diets consistantly had more feathers on the litter than those birds receiving the low protein diets. There were significantly (P < 0.01) more feathers on the litter in the pens containing the Cobb x Cobb birds as compared to the pens containing the Hubbard x Hubbard broiler crosses. POULTRY SCIENCE 55: 1200-1207, 1976
INTRODUCTION HE normal criteria for evaluating the adequacy of practical broiler diets with different nutrient levels are to measure the relative growth and feed efficiency between broilers receiving these diets. From time to time, other criteria such as NPU, biological value and digestibility are used. Gordon and Sizer (1955) also used degree of feathering as another criterion for evaluating the effects
T
1. Scientific Article No. A2139, Contribution No. 5103 of the Maryland Agricultural Experiment Station, Department of Poultry Science. 2. Present Address: Paul Twining Associates, Route 3, Box 354A, Princess Anne, Maryland 21853.
of adding sodium sulfate to the diet. They utilized a subjective scoring system of 0-4 to measure the degree of feathering in the birds. Combs (1956) also used feathering of the birds as an additional parameter for evaluating the effects of varying the C/P ratio on the performance of broilers during the starting and finishing periods. The birds were rated according to the percent of normally feathered birds within each treatment. In a study where the protein level of the diets was held constant and the energy level varied, Turk et al. (1961) observed that birds fed the two highest energy level diets were eating their feathers as fast as they were molted; whereas other pens were covered
Downloaded from http://ps.oxfordjournals.org/ at NERL on April 12, 2015
The Number of Feathers on the Litter; Another Criterion for Evaluating the Adequacy of Broiler Diets'