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A Toe Deformity in the Progeny of Linoleic Acid Deficient Hens
BIOTIN REQUIREMENT or POULTS
about 50 meg. per kg. of diet lower than the male. ACKNOWLEDGEMENTS
Acknowledgement is gratefully extended to Hoffmann-La Roche Inc. and to the Utah Turkey Marketing Board for partial support of these investigations.
of incidence of leg weakness in developing turkeys. Poultry Sci. 48:222-230. McGinnis, J., and J. S. Carver, 1947. The effect of riboflavin and biotin in the prevention of dermatitis and perosis in turkey poults. Poultry Sci. 26: 364-371. National Academy of Sciences—National Research Council, 1966. Publication 1345. Nutrient Requirements of Poultry. Patrick, H., R. V. Boucher, R. A. Dutcher and H. C. Knandel, 1941. Biotin and prevention of dermatitis in turkey poults. Proc. Soc. Exptl. Biol. Med. 48: 456-458. Patrick, H., R. V. Boucher, R. A. Dutcher and H. C. Knandel, 1942. The nutritional significance of biotin in chick and poult nutrition. Poultry Sci. 21: 476. Richardson, C. E., and H. S. Wilgus, 1967. Biotin— a limiting factor in turkey rations? Feedstuffs, August 12, 52-54. Robblee, A. R., and D. R. Clandenin, 1953. The use of calcium pantothenate and biotin in practical poult starters. Poultry Sci. 32: 579-582. Slinger, S. J., and W. F. Pepper, 1954. The effect of antibiotics on the turkey poult's need for supplementary biotin and pantothenic acid. Poultry Sci. 33: 633-637.
A Toe Deformity in the Progeny of Linoleic Acid Deficient Hens HENRY MENGE
United States Department of Agriculture,1 Beltsville, Md. 20705 (Received for publication November 10, 1969)
D
URING the course of our investigations on the linoleic acid (18:2) requirement of the hen for reproduction, a malformation of the toes of newlyhatched chicks was observed. This deformity ascribed to a deficiency of 18:2 was first reported by Menge (1968a). The purpose of this paper is to present detailed observations on the percentage of incidence and the different classes of the severity of the toe abnormality. 1 Animal Husbandry Research Division, A.R.S. Beltsville, Md. 20705.
EXPERIMENTAL PROCEDURE
In the first experiment 18:2 deficient Leghorn hens were distributed into 7 groups of 28 hens each. The groups received a low-fat isolated soy protein diet described by Menge (1968b) supplemented with 18:2 1 as follows: zero 0.125. 0.25, 0.5, 1.0, 2.0, and 4% respectively. 1 Safflower oil supplied by the Procter and Gamble Co., Cincinnati, contained the following fatty acids as determined by gas liquid Chromatography (percentage of total): 14:0, 0.14; 16:0, 6.56; 18:0, 2.62; 18:1, 12.87; 18:2, 77.63; 18:3, 0.18.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
REFERENCES Cravens, W. W., E. E. Sebesta, T. G. Halpin and E. B. Hart, 1942. Effect of biotin on reproduction in the domestic fowl. Proc. Soc. Exptl. Biol. Med. 50:101-104. Griffith, M., R. J. Young and M. L. Scott, 1966. Influence of soybean meal on growth and phosphorus availability in turkey poults. Poultry Sci. 45: 189-199. Jensen, L. S., 1967. Biotin in practical turkey rations. Official Proceedings Second Annual Pacific Northwest Animal Nutrition Conference. Jensen, L. S., and R. Martinson, 1969. Requirement of turkey poults for biotin and effect of deficiency
553
554
H.
MENGE
TABLE 1.—Observations on the number of progeny exhibiting a toe deformity Group No.
Linoleic acid1
Chicks examined2
1 2 3 4 5 6 7
0.0 0.125 0.25 0.50 1.0 2.0 4.0
%
Number 28 1,025 1,400 1,582 1,714 1,902 2,176
Chicks with deformity Number 20 161 28 26 12 8 2
%
71.4 15.7 2.0 1.6 0.7 0.4 0.1
Limits of confidence3
%
51.3-86.8» 13.5-18.0 b 1.3- 2.7-= 1.0- 2.2"^ 0.3- l . l d e 0 . 1 - 0.7 ef 0.0- 0.2'
Hatching d a t a from this experiment were collected from 20 consecutive weekly hatches (Table 1). T h e second experiment comprised 12 groups of 15 hens each. Groups 1 through 11, deficient in 18:2, received the isolated soy protein diet supplemented with 18:2 as follows: zero, 0.125, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, and 6 % respectively. This experiment included a control group (group 12, Table 2) fed a practical-type grower and breeder ration (calculated to contain
approximately 1.2% 18:2). Hatching d a t a from this experiment were collected from 7 consecutive monthly hatches. T h e percentage of incidence of toe deformities observed in both experiments was calculated from the number of chicks hatched from each group (Tables 1 and 2). Arbit r a r y standards of the severity of the deformity were used in experiment 2 (Table 3). Five grades were used as follows: (1) One toe curled on one foot; (2) Two toes curled (one on each foot);
TABLE 2.—The number and percentage of newly-hatched chicks with a toe deformity Group No.
Linoleic acid1
No. chicks2 examined
1 2 3 4 5 6 7 8 9 10 11 12
0.0 0.125 0.25 0.5 0.75 1.0 1.5 2.0 3.0 4.0 6.0 Control 5
%
Number 04 177 328 341 354 397 439 505 538 514 511 585
Chicks with deformity Number 0 39 45 29 19 14 14 13 10 17 9 13
Limits of confidence3
%
%
22.0 13.7 8.5 5.4 3.5 3.2 2.6 1.9 3.3 1.7 2.2
15.9-28.9* 10.5-18.0» b 6.1-12.O^ 3 . 6 - &.3°* 2 . 2 - 5.9 de 2 . 0 - 5.3 d " 1.6- 4.4 d e 1.1- 3.4° 2.2- 5.3 d e 1.0- 3.3" 1.2- 3.8 d e
1 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets fed to linoleic acid deficient dams in groups 1 through 11. 2 Total number of chicks hatched from each group. 3 The lower and upper 95% confidence limits for the estimated percentage. Groups with the same letter in the superscript are not significantly different at the 5% level. 4 Zero hatch due to severe linoleic acid deficiency. 6 Practical-type breeder ration calculated to contain approximately 1.2% linoleic acid. Dams not deficient in linoleic acid.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
1 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets fed to linoleic acid deficient dams in groups 1 through 7. 2 Total number of chicks hatched from each group. 3 The lower and upper 95% confidence limits for the estimated percentage. Groups with the same letter in the superscript are not significantly different at the 5% level.
555
CHICK T O E DEFORMITY TABLE 3.—The occurrence of the toe abnormality by degree of severity Degree of severity 1 Group No.
Linoleic acid2
Chicks examined3
% 0.0 0.125 0.25 0.5 0.75 1.0 1.5 2.0 3.0 4.0 6.0 Control 5
0" 177 328 341 354 397 439 505 538 514 511 585
2
3
4
5
Chicks affected
Chicks affected
Chicks affected
Chicks affected
Chicks affected
% —
%
% —
% —
% —
4.0 6.0 3.5 2.8 1.5 3.0 1.3 1.5 2.5 1.6 1.3
7.9 2.7 2.1 0.3 1.0 0.0 1.0 0.0 0.6 0.0 0.3
4.0 1.8 1.4 1.1 0.3 0.0 0.2 0.4 0.0 0.0 0.3
2.3 1.2 1.2 0.8 0.5 0.0 0.0 0.0 0.0 0.0 0.0
3.4 1.2 0.3 0.3 0.3 0.2 0.0 0.0 0.2 0.2 0.2
1 Severity graded as follows: (1) one curled toe; (2) two curled toes (one on each foot); (3) all toes curled on one foot, other foot normal; (4) one toe curled on one foot with all toes on other foot curled; (5) all toes on each foot curled. 2 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets for linoleic acid deficient dams (groups 1 through 11). 3 Total number of chicks hatched in each group. 4 Zero hatch due to severe linoleic acid deficiency. 5 Practical-type breeder ration calculated to contain 1.2% linoleic acid. Dams not deficient in linoleic acid.
dietary 18:2 in group 7 (4%). Table 2 presents the results obtained in experiment 2. A larger and more efficient fat extractor than the one used in experiment 1 was employed in experiRESULTS AND DISCUSSION ment 2. The increased efficiency in the The data in Table 1 show the total num- extraction of fat from the feedstuffs used ber of chicks examined, the number and in experiment 2 resulted in a more severe the percentage of chicks affected with the 18:2 deficiency in the dams which was toe deformity in experiment 1. The per- reflected in zero percent hatchability in centage incidence of the deformity dimin- contrast to the 1.8% hatchability obished significantly in the progeny of served in experiment 1. The number and groups 1 through 3 with each increase in the percentage of chicks with toe abnorthe level of 18:2 (safflower oil) given the malities followed approximately the same dams. There was a decline in the per- pattern as that observed in experiment 1. centage of incidence of the toe deformity The addition of 18:2 to the diet of the in the remaining groups as the level of dams was, however, not as effective in 18:2 given the dams was increased. the reduction of the percentage incidence Further significant decreases in the num- of the toe deformity in this experiment ber of progeny with deformed toes, how- as it was in experiment 1. This difference ever, required an 8-fold increase in the may be ascribed to the reduced number level of dietary 18:2 (2% in group 6), of observations as compared with those in and an additional 4-fold increase of experiment 1. (3) All toes curled on one foot, other foot normal; (4) One toe curled on one foot with all toes on other foot curled; (5) All toes on each foot curled.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
1 2 3 4 5 6 7 8 9 10 11 12
1
556
H.
MENGE
T h e most severe of the curled toe abnormalities in which all toes on both feet of the newly-hatched chick are curled is identical with those t h a t appear in a riboflavin deficient growing chicken. T h e deficiency of 18:2 in the present study is, however, not complicated by a deficiency of this vitamin since the dams received
16 mg. riboflavin per kg. of diet. Riboflavin deficient embryos are dwarfed and edematous (Scott et ah, 1969) whereas those observed in the present study were normal in every respect except for t h e toe abnormality. SUMMARY A number of day-old progeny of 18:2deficient dams were observed with malformed toes. Increased levels of 18:2 (safflower oil) in the diet of the d a m resulted in a significant decrease in both incidence and the severity of the toe abnormality. Since this abnormality was also noted in progeny of dams receiving a complete practical t y p e diet and is observed infrequently in normal hatches, it appears t h a t the deficiency of 18:2 is not the only factor involved. I t is probable t h a t the genetic constitution of the d a m and progeny is also implicated. T h e deficiency of 18:2 m a y have possibly exerted a stress on some metabolic processes to permit a more frequent expression of the curled toe phenotype. ACKNOWLEDGMENT T h e author wishes to acknowledge the help of D r . Judson U. McGuire, Jr. of the Biometrical Services Staff, Agricultural Research Service, Beltsville, M a r y land 20705 REFERENCES Menge, H., 1968a. The linoleic acid requirement of the hen for reproduction. Poultry Sci. 47:1695. Menge, H., 1968b. Linoleic acid requirement of the hen for reproduction. J. Nutr. 95:578-582. Scott, M. L., M. C. Nesheim and R. J. Young, 1969. Nutrition of the Chicken. M. L. Scott and Associates, Ithaca, New York, pages 181-189.
S E P T E M B E R 3-9. 8 T H I N T I R N A T I O N A L C O N G R E S S O F , ROME, ITALY S E P T E M B E R 6-12. F O U R T E E N T H W O R L D ' S P O U L T R Y CONGRESS, M A D R I D , SPAIN
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
T h e occurrence of the toe deformity segregated into 5 degrees of severity and expressed in percentage of total number of progeny is shown in Table 3. I t is a p p a r e n t from these observations t h a t the larger percentages of the most severe cases of the toe deformity occur in the progeny of dams receiving the lowest level of 18:2. Although the toe abnormality occurs more frequently and with greater severity in the progeny of 18:2 deficient hens, the addition of 18:2 to the diet of the d a m does not preclude the occurrence of the abnormality. This shows t h a t the deficiency of 18:2 is not the only factor involved in the incidence of the toe deformity. Chicks hatched from dams fed a practical-type grower and breeder ration can be considered replete in all known required nutrients, including 18:2 (Table 2 and 3, group 12). Despite this fact, a relatively small number of chicks have hatched with some degree of the toe deformity. This phenomenon is apparently not uncommon for it appears routinely. Since both 18:2 and possibly the genetic constitution of the d a m and progeny are involved, the lack of 18:2 appears to exert a stress on some metabolic processes t h a t permits a more frequent expression of this phenotype.
about 50 meg. per kg. of diet lower than the male. ACKNOWLEDGEMENTS
Acknowledgement is gratefully extended to Hoffmann-La Roche Inc. and to the Utah Turkey Marketing Board for partial support of these investigations.
of incidence of leg weakness in developing turkeys. Poultry Sci. 48:222-230. McGinnis, J., and J. S. Carver, 1947. The effect of riboflavin and biotin in the prevention of dermatitis and perosis in turkey poults. Poultry Sci. 26: 364-371. National Academy of Sciences—National Research Council, 1966. Publication 1345. Nutrient Requirements of Poultry. Patrick, H., R. V. Boucher, R. A. Dutcher and H. C. Knandel, 1941. Biotin and prevention of dermatitis in turkey poults. Proc. Soc. Exptl. Biol. Med. 48: 456-458. Patrick, H., R. V. Boucher, R. A. Dutcher and H. C. Knandel, 1942. The nutritional significance of biotin in chick and poult nutrition. Poultry Sci. 21: 476. Richardson, C. E., and H. S. Wilgus, 1967. Biotin— a limiting factor in turkey rations? Feedstuffs, August 12, 52-54. Robblee, A. R., and D. R. Clandenin, 1953. The use of calcium pantothenate and biotin in practical poult starters. Poultry Sci. 32: 579-582. Slinger, S. J., and W. F. Pepper, 1954. The effect of antibiotics on the turkey poult's need for supplementary biotin and pantothenic acid. Poultry Sci. 33: 633-637.
A Toe Deformity in the Progeny of Linoleic Acid Deficient Hens HENRY MENGE
United States Department of Agriculture,1 Beltsville, Md. 20705 (Received for publication November 10, 1969)
D
URING the course of our investigations on the linoleic acid (18:2) requirement of the hen for reproduction, a malformation of the toes of newlyhatched chicks was observed. This deformity ascribed to a deficiency of 18:2 was first reported by Menge (1968a). The purpose of this paper is to present detailed observations on the percentage of incidence and the different classes of the severity of the toe abnormality. 1 Animal Husbandry Research Division, A.R.S. Beltsville, Md. 20705.
EXPERIMENTAL PROCEDURE
In the first experiment 18:2 deficient Leghorn hens were distributed into 7 groups of 28 hens each. The groups received a low-fat isolated soy protein diet described by Menge (1968b) supplemented with 18:2 1 as follows: zero 0.125. 0.25, 0.5, 1.0, 2.0, and 4% respectively. 1 Safflower oil supplied by the Procter and Gamble Co., Cincinnati, contained the following fatty acids as determined by gas liquid Chromatography (percentage of total): 14:0, 0.14; 16:0, 6.56; 18:0, 2.62; 18:1, 12.87; 18:2, 77.63; 18:3, 0.18.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
REFERENCES Cravens, W. W., E. E. Sebesta, T. G. Halpin and E. B. Hart, 1942. Effect of biotin on reproduction in the domestic fowl. Proc. Soc. Exptl. Biol. Med. 50:101-104. Griffith, M., R. J. Young and M. L. Scott, 1966. Influence of soybean meal on growth and phosphorus availability in turkey poults. Poultry Sci. 45: 189-199. Jensen, L. S., 1967. Biotin in practical turkey rations. Official Proceedings Second Annual Pacific Northwest Animal Nutrition Conference. Jensen, L. S., and R. Martinson, 1969. Requirement of turkey poults for biotin and effect of deficiency
553
554
H.
MENGE
TABLE 1.—Observations on the number of progeny exhibiting a toe deformity Group No.
Linoleic acid1
Chicks examined2
1 2 3 4 5 6 7
0.0 0.125 0.25 0.50 1.0 2.0 4.0
%
Number 28 1,025 1,400 1,582 1,714 1,902 2,176
Chicks with deformity Number 20 161 28 26 12 8 2
%
71.4 15.7 2.0 1.6 0.7 0.4 0.1
Limits of confidence3
%
51.3-86.8» 13.5-18.0 b 1.3- 2.7-= 1.0- 2.2"^ 0.3- l . l d e 0 . 1 - 0.7 ef 0.0- 0.2'
Hatching d a t a from this experiment were collected from 20 consecutive weekly hatches (Table 1). T h e second experiment comprised 12 groups of 15 hens each. Groups 1 through 11, deficient in 18:2, received the isolated soy protein diet supplemented with 18:2 as follows: zero, 0.125, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, and 6 % respectively. This experiment included a control group (group 12, Table 2) fed a practical-type grower and breeder ration (calculated to contain
approximately 1.2% 18:2). Hatching d a t a from this experiment were collected from 7 consecutive monthly hatches. T h e percentage of incidence of toe deformities observed in both experiments was calculated from the number of chicks hatched from each group (Tables 1 and 2). Arbit r a r y standards of the severity of the deformity were used in experiment 2 (Table 3). Five grades were used as follows: (1) One toe curled on one foot; (2) Two toes curled (one on each foot);
TABLE 2.—The number and percentage of newly-hatched chicks with a toe deformity Group No.
Linoleic acid1
No. chicks2 examined
1 2 3 4 5 6 7 8 9 10 11 12
0.0 0.125 0.25 0.5 0.75 1.0 1.5 2.0 3.0 4.0 6.0 Control 5
%
Number 04 177 328 341 354 397 439 505 538 514 511 585
Chicks with deformity Number 0 39 45 29 19 14 14 13 10 17 9 13
Limits of confidence3
%
%
22.0 13.7 8.5 5.4 3.5 3.2 2.6 1.9 3.3 1.7 2.2
15.9-28.9* 10.5-18.0» b 6.1-12.O^ 3 . 6 - &.3°* 2 . 2 - 5.9 de 2 . 0 - 5.3 d " 1.6- 4.4 d e 1.1- 3.4° 2.2- 5.3 d e 1.0- 3.3" 1.2- 3.8 d e
1 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets fed to linoleic acid deficient dams in groups 1 through 11. 2 Total number of chicks hatched from each group. 3 The lower and upper 95% confidence limits for the estimated percentage. Groups with the same letter in the superscript are not significantly different at the 5% level. 4 Zero hatch due to severe linoleic acid deficiency. 6 Practical-type breeder ration calculated to contain approximately 1.2% linoleic acid. Dams not deficient in linoleic acid.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
1 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets fed to linoleic acid deficient dams in groups 1 through 7. 2 Total number of chicks hatched from each group. 3 The lower and upper 95% confidence limits for the estimated percentage. Groups with the same letter in the superscript are not significantly different at the 5% level.
555
CHICK T O E DEFORMITY TABLE 3.—The occurrence of the toe abnormality by degree of severity Degree of severity 1 Group No.
Linoleic acid2
Chicks examined3
% 0.0 0.125 0.25 0.5 0.75 1.0 1.5 2.0 3.0 4.0 6.0 Control 5
0" 177 328 341 354 397 439 505 538 514 511 585
2
3
4
5
Chicks affected
Chicks affected
Chicks affected
Chicks affected
Chicks affected
% —
%
% —
% —
% —
4.0 6.0 3.5 2.8 1.5 3.0 1.3 1.5 2.5 1.6 1.3
7.9 2.7 2.1 0.3 1.0 0.0 1.0 0.0 0.6 0.0 0.3
4.0 1.8 1.4 1.1 0.3 0.0 0.2 0.4 0.0 0.0 0.3
2.3 1.2 1.2 0.8 0.5 0.0 0.0 0.0 0.0 0.0 0.0
3.4 1.2 0.3 0.3 0.3 0.2 0.0 0.0 0.2 0.2 0.2
1 Severity graded as follows: (1) one curled toe; (2) two curled toes (one on each foot); (3) all toes curled on one foot, other foot normal; (4) one toe curled on one foot with all toes on other foot curled; (5) all toes on each foot curled. 2 Linoleic acid supplied by safflower oil to supplement isolated soy protein diets for linoleic acid deficient dams (groups 1 through 11). 3 Total number of chicks hatched in each group. 4 Zero hatch due to severe linoleic acid deficiency. 5 Practical-type breeder ration calculated to contain 1.2% linoleic acid. Dams not deficient in linoleic acid.
dietary 18:2 in group 7 (4%). Table 2 presents the results obtained in experiment 2. A larger and more efficient fat extractor than the one used in experiment 1 was employed in experiRESULTS AND DISCUSSION ment 2. The increased efficiency in the The data in Table 1 show the total num- extraction of fat from the feedstuffs used ber of chicks examined, the number and in experiment 2 resulted in a more severe the percentage of chicks affected with the 18:2 deficiency in the dams which was toe deformity in experiment 1. The per- reflected in zero percent hatchability in centage incidence of the deformity dimin- contrast to the 1.8% hatchability obished significantly in the progeny of served in experiment 1. The number and groups 1 through 3 with each increase in the percentage of chicks with toe abnorthe level of 18:2 (safflower oil) given the malities followed approximately the same dams. There was a decline in the per- pattern as that observed in experiment 1. centage of incidence of the toe deformity The addition of 18:2 to the diet of the in the remaining groups as the level of dams was, however, not as effective in 18:2 given the dams was increased. the reduction of the percentage incidence Further significant decreases in the num- of the toe deformity in this experiment ber of progeny with deformed toes, how- as it was in experiment 1. This difference ever, required an 8-fold increase in the may be ascribed to the reduced number level of dietary 18:2 (2% in group 6), of observations as compared with those in and an additional 4-fold increase of experiment 1. (3) All toes curled on one foot, other foot normal; (4) One toe curled on one foot with all toes on other foot curled; (5) All toes on each foot curled.
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
1 2 3 4 5 6 7 8 9 10 11 12
1
556
H.
MENGE
T h e most severe of the curled toe abnormalities in which all toes on both feet of the newly-hatched chick are curled is identical with those t h a t appear in a riboflavin deficient growing chicken. T h e deficiency of 18:2 in the present study is, however, not complicated by a deficiency of this vitamin since the dams received
16 mg. riboflavin per kg. of diet. Riboflavin deficient embryos are dwarfed and edematous (Scott et ah, 1969) whereas those observed in the present study were normal in every respect except for t h e toe abnormality. SUMMARY A number of day-old progeny of 18:2deficient dams were observed with malformed toes. Increased levels of 18:2 (safflower oil) in the diet of the d a m resulted in a significant decrease in both incidence and the severity of the toe abnormality. Since this abnormality was also noted in progeny of dams receiving a complete practical t y p e diet and is observed infrequently in normal hatches, it appears t h a t the deficiency of 18:2 is not the only factor involved. I t is probable t h a t the genetic constitution of the d a m and progeny is also implicated. T h e deficiency of 18:2 m a y have possibly exerted a stress on some metabolic processes to permit a more frequent expression of the curled toe phenotype. ACKNOWLEDGMENT T h e author wishes to acknowledge the help of D r . Judson U. McGuire, Jr. of the Biometrical Services Staff, Agricultural Research Service, Beltsville, M a r y land 20705 REFERENCES Menge, H., 1968a. The linoleic acid requirement of the hen for reproduction. Poultry Sci. 47:1695. Menge, H., 1968b. Linoleic acid requirement of the hen for reproduction. J. Nutr. 95:578-582. Scott, M. L., M. C. Nesheim and R. J. Young, 1969. Nutrition of the Chicken. M. L. Scott and Associates, Ithaca, New York, pages 181-189.
S E P T E M B E R 3-9. 8 T H I N T I R N A T I O N A L C O N G R E S S O F , ROME, ITALY S E P T E M B E R 6-12. F O U R T E E N T H W O R L D ' S P O U L T R Y CONGRESS, M A D R I D , SPAIN
Downloaded from http://ps.oxfordjournals.org/ at Bibliotheque de l'Universite Laval on May 10, 2015
T h e occurrence of the toe deformity segregated into 5 degrees of severity and expressed in percentage of total number of progeny is shown in Table 3. I t is a p p a r e n t from these observations t h a t the larger percentages of the most severe cases of the toe deformity occur in the progeny of dams receiving the lowest level of 18:2. Although the toe abnormality occurs more frequently and with greater severity in the progeny of 18:2 deficient hens, the addition of 18:2 to the diet of the d a m does not preclude the occurrence of the abnormality. This shows t h a t the deficiency of 18:2 is not the only factor involved in the incidence of the toe deformity. Chicks hatched from dams fed a practical-type grower and breeder ration can be considered replete in all known required nutrients, including 18:2 (Table 2 and 3, group 12). Despite this fact, a relatively small number of chicks have hatched with some degree of the toe deformity. This phenomenon is apparently not uncommon for it appears routinely. Since both 18:2 and possibly the genetic constitution of the d a m and progeny are involved, the lack of 18:2 appears to exert a stress on some metabolic processes t h a t permits a more frequent expression of this phenotype.