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Riboflavin Requirement of Broiler Chicks Fed a Corn-Soybean Diet1
Riboflavin Requirement of Broiler Chicks Fed a Corn-Soybean Diet 1 N. RUIZ2 and R. H. HARMS3 Department of Poultry Science, University of Florida, Gainesville, Florida 32611 (Received for publication March 23, 1987)
1988 Poultry Science 67:794-799 INTRODUCTION
The role of riboflavin in poultry nutrition was studied intensively by several groups of researchers from the beginning of the 1930's to tbe mid-1940's. Therefore, by the time the first revision of the Recommended Nutrient Allowances for Poultry (National Research Council, NBC, 1946) was published, the riboflavin allowance of 3.5 mg/kg of feed for chickens from 0 to 8 wk of age was already established. When the National Research Council decided to change from allowances to requirements in 1954 (Heuser, 1955), a minimum requirement of approximately 2.9 mg of riboflavin/kg diet was suggested. However, since publication of the fifth edition of the Nutrient Requrements of Poultry (Titus and Fritz, 1971), the minimum requirement suggested has been 3.6 mg riboflavin/kg feed, which essentially reflects the requirement reported by Heuser et al. (1938), Bethke and Record (1942), Bolton (1944; 1947), and Bird et al. (1946). Considering the faster growth rate of today's broiler strains in compari-
Florida Agricultural Experiment Station Journal Series Number 8010. 2 Present address: Cargill, Nutrena Feed Division, P. O. Box 5614, Minneapolis, MN 55440. 3 To whom correspondence should be addressed. 794
son with that of the strains of 30 or 40 years ago, it was deemed of interest to re-evaluate the riboflavin requirement of broiler chicks from 1 to 21 days ofage using a corn-soybean meal diet. MATERIALS AND METHODS
Two experiments were conducted using a total of 768 day-old broiler chicks. In each experiment 384 birds were assigned to the six dietary treatments of 0, .9, 2.0, 2.8, 3.6, and 4.4 mg of supplemental riboflavin/kg basal diet. Eight replicates of eight birds/pen (four female and four male chicks) were used per treatment. In the first experiment Cobb X Arbor Acres birds were used, whereas in the second experiment birds were of the Cobb x Cobb cross. Both flocks of broiler breeders were fed a level of riboflavin that exceeded the NRC (1984) recommendation. The corn-soybean meal basal diet was formulated to contain 22% CP (Table 1). The vitamin premix was formulated to be devoid of riboflavin. The CP (percentage N X 6.25), moisture, and ether extract contents of the basal diets were determined according to the methods of the Association of Official Analytical Chemists (AOAC, 1984). Riboflavin contents of the basal diets were analyzed by a commercial laboratory (Hazelton Laboratories America, Inc., Chemical & BioMedical Sciences Division, Madison, WI) by the microbiological method according
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
ABSTRACT Two 21 -day battery experiments were conducted with day-old broiler chicks fed a corn-soybean meal diet to re-evaluate the riboflavin requirement for optimum performance. In each experiment a total of 384 birds was assigned to six dietary treatments and given 0, 0.9, 2.0, 2.8, 3.6, or 4.4 mg of supplemental riboflavin/kg of feed. The corn-soybean meal diet was formulated to contain 22% CP and 3,200 kcal of ME/kg of feed. The analyzed riboflavin content of the unsupplemented diet was 2.6 mg/kg. A severe leg paralysis (inability to walk and to move one or both legs) was first observed between 10 to 12 days of age in birds receiving no supplemental riboflavin. Besides leg paralysis, high mortality and poor growth were the main signs of riboflavin deficiency observed. A minimum requirement for growth of 3.6 mg of riboflavin/ kg of feed was determined using the broken-line technique. However, in order to prevent signs of leg paralysis, the minimum requirement of 4.6 mg riboflavin/kg of feed was suggested. Based on the maximum feed intake (834 g) observed for birds to reach maximum body weight (593 g) at 21 days of age, a minimum intake of approximately 6.5 ^g riboflavin/g body weight was needed for maximum performance. (Key words: riboflavin, broiler chick, requirements, corn-soybean diet)
RIBOFLAVIN REQUIREMENTS OF CHICKS TABLE 1. Composition of basal diet Component
Percent
Ingredients Yellow corn Soybean meal ( 4 8 % CP) Animal fat Limestone Dicalcium p h o s p h a t e (22.0% Ca; 18.5% P) Salt Microingredientsl DL-Methionine
1.75 .40 .50 .22
Calculated^
CP, % 22.0 Moisture, % Ether e x t r a c t , % 7.9 Sulfur a m i n o acids, % .93 Riboflavin, mg/kg 1.6 3,200 ME, kcal/kg
Analyzed^ 21.8 10.8 7.8 2.6
1 Supplied per kilogram of diet: 6,600 IU vitamin A; 2,200 ICU vitamin D3; 2.2 mg menadione dimethylpyrimidinol bisulfite; 39.6 mg niacin; 13.2 mg pantothenic acid; 499 mg choline chloride; 22 Mg vitamin B12; 125 mg ethoxyquin; 60 mg manganese; 50 mg iron; 6 mg copper; .198 mg cobalt; 1.1 mg iodine; 35 mg zinc.
Birds were housed for 21 days in Petersime battery brooders (Petersime Incubator Co., Gettysburg, OH) with raised wire floors. A 24-h constant fluorescent light schedule was maintained in the battery room. Feed and water were offered ad libitum. At the termination of each experiment, male and female chicks were weighed on a per pen basis. In Experiment 1 each bird was visually evaluated for leg disorders . Feed consumption was determined by pen. In order to fit the broken-line linear model, the following procedure was followed: first, an ANOVA for the linear regression (SAS, 1985) was determined on the experimental data; i.e., body weights at 21 days, feed conversion, and feed intake were plotted against mg of supplemental riboflavin in the diet. Second, a family of linear-plateau models as described by Anderson and Nelson (1975) was fitted to the data. The model with the minimum residual sum of squares was chosen as the most adequate brokenline model. The minumum requrement for growth was estimated as the intersection of the ascending line and the plateau. RESULTS AND DISCUSSION
2
National Research Council (1984) table values were used for calculated analysis. 3
Average values of four determinations (two for each basal diet), except for riboflavin, which was determined on a single sample per basal diet.
to AOAC (1984). Crystalline riboflavin was used as the riboflavin supplement (reagent grade, 96% purity, Fisher Scientific Company, Chemical Manufacturing Division, Fair Lawn, NJ).
As the treatment X experiment interactions for body weight and feed intake data were not significant (P = .94 and P = .18, respectively), the data from both experiments were combined (Table 2). Using the broken-line technique (Figure 1) to determine the minimum requirement for riboflavin of broiler chicks from 1 to 21 days of age, it was found that the relationship between body weight, y (grams), and riboflavin level, x (milligrams per kilogram), can be expressed as: y = 272.88 4- 307.64 x
TABLE 2. Performance of broiler chicks fed various levels of supplemental riboflavin from 1 to 21 days of age in a corn-soybean meal diet1 Supplemental riboflavin
Body weight
(mg/kg)
(g)
0
273 550 592 588 605 585
.9 2.0 2.8 3.6 4.4
± ± ± ± ± +
9.7 12.1 12.4 11.3 8.5 12.2
Feed intake
Feed conversion
Leg paralysis incidence 2
(g/bird)
(g feed/g weight)
(%)
485 794 839 828 842 825
1.80 1.45 1.42 1.40 1.39 1.42
100.0 15.9 7.8 0 0 0
± 15.3 ± 8.8 ± 12.3 ± 13.0 ± 9.1 ± 9.4
± ± ± ± ± ±
.06 .03 .02 .01 .02 .02
1
Combined data of Experiments 1 and 2; means and SEM, 16 pens/treatment.
2
Measured in the first experiment only (64 birds/treatment).
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
Analysis
54.56 36.00 5.50 1.07
795
796
RUIZ AND HARMS
age. Mortality at the zero level of riboflavin supplementation was 18.7%. Incidence of leg paralysis decreased considerably by addition of .9 and 2.0 mg riboflavin/kg basal diet. Not only the number of birds exhibiting leg problems decreased with increasing levels of riboflavin supplementation, but also the severity of the disorder. The term ' 'curled-toe paralysis" has not been used here to describe the leg paralysis observed in these experiments because the descriptions given by Norris et al. (1930, 1931) and Bethke et al. (1931), which subsequently were called by Stokstad and Manning (1938) "curled-toe paralysis," did not match the type of leg paralysis that was predominantly observed. At the zero level of riboflavin supplementation, leg paralysis was very severe and involved 100% of the birds, as already mentioned. No "curledtoe paralysis" was observed. When .9 mg supplemental riboflavin was added to the basal diet, there was a substantial decrease in the number of birds with leg problems. Only at this level of riboflavin supplemen-
ts
Z.O
2.5
3.0
3.5
t.O
4.5
S U P P l E I E I t U I I I O F L M M I IIC/KG
FIGURE 1. Broken-line model applied to the relationship between supplemental dietary riboflavin and body weight at 21 days of age. Ascending portion, y = 272.88 + 307.64 x. Plus sign = predicted equation; square = mean value. Bars = SEM.
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
where supplemental riboflavin was less than 2.0 mg/kg feed. The coefficient of determination value is defined here as: R2 = [TSS(S + H)-SSE(S + H)]/ TSS(S + H) where TSS = total sum of squares, SSE = sum of squares for error, and the letters S and H = the sloping and horizontal portions of the curve, respectively. The R2 for the brokenline model was .79. The intersection between the sloping line and the plateau was at 1.0 mg supplemental riboflavin/kg of diet. As the analyzed riboflavin content of the basal diets was 2.6 mg/kg (Table 1), the minimum riboflavin requirement for growth of broiler chicks to 21 days of age was estimated to be 3.6 mg/kg feed. Feed intake increased and feed conversion improved until a level of 2.0 mg supplemental riboflavin/kg feed was reached. The minimum requirement of 3.6 mg riboflavin/kg feed as determined by the broken-line technique is identical to the minimum requirement currently suggested by NRC (1984). This suggested requirement has remained almost unmodified since 1946 (NRC, 1946) after the work of several researchers. Norris et al. (1936) reported that chicks needed approximately 2.9 mg of riboflavin/kg feed in order to attain normal weight at 8 wk of age. Bethke and Record (1942) suggested a minimum of 2.5 mg/kg for growth but more than 3.0 mg riboflavin/kg feed for complete protection against leg paralysis (curled toe paralysis). Bird et al. (1946) indicated that 2.75 to 3.25 mg riboflavin/kg feed was adequate for growth and even less was needed for complete prevention of leg paralysis (curled toe paralysis). Although White Leghorn chicks were used by most of the aforementioned authors, Bolton (1944) determined the riboflavin requirement of the White Wyandotte chick and reported that 3.0 mg riboflavin/kg feed was the minimum requirement for optimum growth to 6 wk of age, and 3.6 mg for the prevention of leg paralysis (curled toe paralysis). The signs of deficiency observed when the corn-soybean meal diet without supplemental riboflavin was fed to broiler chicks from 1 to 21 days of age were severe leg paralysis (inability to walk, and inability to move one or both legs) as illustrated in Figure 2, high mortality, and poor growth. In the first experiment in which quantification of incidence of leg paralysis was carried out, 100% of the surviving birds were paralyzed at 21 days when no riboflavin was added to the basal diet. However, leg paralysis was first observed between 10 to 12 days of
RIBOFLAVIN REQUIREMENTS OF CHICKS
797
A RIBOFLAVIN
>*is
•m • # >
B RIBOFLAVIN
r; *!W^. ^
$
FIGURE 2. Riboflavin deficiency in broiler chicks at 21 days of age. A, the bird at left was fed a corn-soybean meal diet without supplemental riboflavin. This chicks exhibited the predominant type of paralysis observed at the zero level of riboflavin supplementation. The bird at right was fed the same basal diet, but adequate in riboflavin. Both birds were females. B, same as A, but male chicks.
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
1
798
RUIZ AND HARMS
imately 1 mg of riboflavin/kg feed; therefore, a total of 3.6 mg/kg feed is adequate for maximum growth. It is possible that the requirement may be slightly higher in the event that the response curve is curvilinear near the point of maximum growth. However, as already mentioned, at 2.0 mg supplemental riboflavin only a slight leg weakness was observed in five birds out of 64. At this level also, feed intake was maximized and feed efficiency was improved. Consequently, it is suggested that at least 4.6 mg of riboflavin/kg feed are needed for maximum growth and prevention of leg paralysis in broiler chicks from 1 to 21 days of age. As the average feed intake per bird (total feed intake during the 21-day experimental period) maximized at 834 g, and the body weight plateau was 593 g, a minimum intake of approximately 6.5 |xg riboflavin/g body weight was needed for maximum performance. ACKNOWLEDGMENTS
Appreciation is expressed to Ramon C. Littell and Steve B. Linda for their assistance in the statistical analysis. REFERENCES Anderson, R. L., and L. A. Nelson, 1975. A family of models involving intersecting straight lines and concomitant experimental designs useful in evaluating response to fertilizer nutrients. Biometrics 31:303-318. Association of Official Analytical Chemists, 1984. Official Methods of Analysis. 14th ed. Association of Official Analytical Chemists, Arlington, VA. Bethke, R. M., and P. R. Record, 1942. The relation of riboflavin to growth and curled-toe paralysis in chicks. Poultry Sci. 21:147-154. Bethke, R. M., P. R. Record, and D. C. Kennard, 1931. A type of nutritional leg paralysis affecting chicks. Poultry Sci. 10:355-368. Bird, F. H., V. S. Asmundson, F. H. Kratzer, and S. Lepkovsky, 1946. The comparative requirements of chicks and turkey poults for riboflavin. Poultry Sci. 25:47-51. Bolton, W., 1944. The riboflavin requirement of the White Wyandotte chick. J. Agric. Sci. 34:198-206. Bolton, W., 1947. The riboflavin requirement of the White Wyandotte chick. II. Pure crystalline riboflavin as the vitamin supplement. J. Agric. Sci. 37: 316-322. Gries, C. L., and M. L. Scott, 1972. The pathology of thiamin, riboflavin, pantothenic acid and niacin deficiencies in the chick. J. Nutr. 102:1269-1286. Heuser, G. F., 1955. Feeding Poultry, 2nd ed. John Wiley and Sons, Inc., New York, NY. Heuser, G. F., H. S. Wilgus, and L. C. Norris, 1938. The quantitative vitamin-G requirement of chicks. Poultry Sci. 17:105-108. Johnson, W. D., 1976. A study of the pathogenesis of the peripheral neuropathy associated with riboflavin deficiency in the chicken. Diss. Abstr. 378:1136-1137.
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
tation did the predominant paralysis observed appear similar to the curled-toe description. Birds rested on their hocks, with their toes curled. Movement was difficult; however, they were able to reach feed and water. But in quantitative terms 15.9% of the birds receiving .9 mg of supplemental riboflavin were exhibiting leg paralysis. At 2.0 mg of supplemental riboflavin/kg feed (4.6 mg total riboflavin/kg feed) only five birds out of 64 (7.8%) displayed a slight leg difficulty, which was characterized by slight shaking of the legs for a few seconds when standing up. No birds showed signs of curled-toe paralysis. The leg paralysis described above has been reported by Wyatt et al. (1973), who conducted several experiments with broiler chicks of three different strains with the objective of defining the signs of riboflavin deficiency. These authors indicated that curled-toe paralysis was not the predominant sign of riboflavin deficiency in broiler chicks. Johnson (1976) indicated that partial or complete paralysis was observed in chicks fed a diet containing 1.65 mg riboflavin/ kg diet, between 12 to 20 days of age, and Jortner et al. (1985), working with a diet containing 1.8 mg riboflavin/kg feed, found that broiler chicks showed neurological signs as early as 7 days of age that included weakness, paralysis, and on occasion curled toes. Although Gries and Scott (1972) reported 20% mortality of birds fed a basal diet containing .3 mg of riboflavin/kg diet, these authors did not observe paralysis in the surviving birds. Gries and Scott (1972) did not observe the enlargement of the sciatic nerve in severely riboflavin deficient birds as described by Phillips and Engel (1938). However, Jortner et al. (1985) reported that the sciatic nerve of riboflavin-deficient birds had a demyelinating neuropathy at 15 days of age. It is hypothesized that the severe paralysis observed is related to the growth rate of the modern broiler chicken. The latter grows faster than the White Leghorn and crossbred chicks of approximately 50 and 40 yr ago. As a faster growth rate is proportionally correlated the greater feed intake, it appears that the riboflavin requirement, expressed as concentration of the diet, remains almost the same as 40 yr ago. However, beacuse feed efficiency is much higher today, the deficiency of riboflavin is much more critical and becomes more severe than before. It is clear from the broken-line model that growth maximized with the addition of approx-
RIBOFLAVIN REQUIREMENTS OF CHICKS
Heiman, and G. F. Heuser, 1936. The vitamin-G requirement of poultry. Cornell Univ. Agric. Exp. Sta. Bull. 660. Ithaca, NY. Phillips, P. H., and R. W. Engel, 1938. The histopathology of neuromalacia and "curled-toe" paralysis in the chick fed low riboflavin diets. J. Nutr. 16:451-463. SAS, 1985. SAS User's Guide: Statistics. SAS Institute Inc., Cary, NC. Stokstad, E.L.R., and P.D.V. Manning, 1938. The effect of riboflavin on the incidence of curled toe paralysis in chicks. J. Nutr. 16:279-283. Titus, H. W., and J. C. Fritz, 1971. The Scientific Feeding of Chickens. 5th ed. The Interstate Printers and Publishers, Inc., Danville, EL. Wyatt, R. D., H. T. Ting, W. E. Donaldson, and P. B. Hamilton, 1973. A new description of riboflavin deficiency syndrome in chickens. Poultry Sci. 52:237244.
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
(Abstr.) Jortner, B. S., J. A. Cherry, andM. Ehrich, 1985. Peripheral neuropathy of dietary riboflavin deficiency in chickens. J. Neuropathol. & Exp. Neurol. 43:342. (Abstr.) National Research Council, 1947. Recommended nutrient allowances for poultry. Mimeographed release. Pages 1300-1305 in: Poultry Nutrition. W. R. Ewing, ed. 3rd ed. South Pasadena, CA. National Research Council, 1984. Nutrient Requirements of Poultry, 8th ed. Natl. Acad. Press, Washington, DC. Norris, L. C , G. F. Heuser, and H. S. Wilgus, Jr., 1930. Is the chief value of milk for feeding poultry due to the presence of a new vitamin? Poultry Sci. 9:133-140. Norris, L. C , G. F. Heuser, and H. S. Wilgus, Jr., 1931. The occurence in chicks of a paralysis of nutritive origin. Poultry Sci. 10:93-97. Norris, L. C , H. S. Wilgus, Jr., A. T. Ringrose, V.
799
1988 Poultry Science 67:794-799 INTRODUCTION
The role of riboflavin in poultry nutrition was studied intensively by several groups of researchers from the beginning of the 1930's to tbe mid-1940's. Therefore, by the time the first revision of the Recommended Nutrient Allowances for Poultry (National Research Council, NBC, 1946) was published, the riboflavin allowance of 3.5 mg/kg of feed for chickens from 0 to 8 wk of age was already established. When the National Research Council decided to change from allowances to requirements in 1954 (Heuser, 1955), a minimum requirement of approximately 2.9 mg of riboflavin/kg diet was suggested. However, since publication of the fifth edition of the Nutrient Requrements of Poultry (Titus and Fritz, 1971), the minimum requirement suggested has been 3.6 mg riboflavin/kg feed, which essentially reflects the requirement reported by Heuser et al. (1938), Bethke and Record (1942), Bolton (1944; 1947), and Bird et al. (1946). Considering the faster growth rate of today's broiler strains in compari-
Florida Agricultural Experiment Station Journal Series Number 8010. 2 Present address: Cargill, Nutrena Feed Division, P. O. Box 5614, Minneapolis, MN 55440. 3 To whom correspondence should be addressed. 794
son with that of the strains of 30 or 40 years ago, it was deemed of interest to re-evaluate the riboflavin requirement of broiler chicks from 1 to 21 days ofage using a corn-soybean meal diet. MATERIALS AND METHODS
Two experiments were conducted using a total of 768 day-old broiler chicks. In each experiment 384 birds were assigned to the six dietary treatments of 0, .9, 2.0, 2.8, 3.6, and 4.4 mg of supplemental riboflavin/kg basal diet. Eight replicates of eight birds/pen (four female and four male chicks) were used per treatment. In the first experiment Cobb X Arbor Acres birds were used, whereas in the second experiment birds were of the Cobb x Cobb cross. Both flocks of broiler breeders were fed a level of riboflavin that exceeded the NRC (1984) recommendation. The corn-soybean meal basal diet was formulated to contain 22% CP (Table 1). The vitamin premix was formulated to be devoid of riboflavin. The CP (percentage N X 6.25), moisture, and ether extract contents of the basal diets were determined according to the methods of the Association of Official Analytical Chemists (AOAC, 1984). Riboflavin contents of the basal diets were analyzed by a commercial laboratory (Hazelton Laboratories America, Inc., Chemical & BioMedical Sciences Division, Madison, WI) by the microbiological method according
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
ABSTRACT Two 21 -day battery experiments were conducted with day-old broiler chicks fed a corn-soybean meal diet to re-evaluate the riboflavin requirement for optimum performance. In each experiment a total of 384 birds was assigned to six dietary treatments and given 0, 0.9, 2.0, 2.8, 3.6, or 4.4 mg of supplemental riboflavin/kg of feed. The corn-soybean meal diet was formulated to contain 22% CP and 3,200 kcal of ME/kg of feed. The analyzed riboflavin content of the unsupplemented diet was 2.6 mg/kg. A severe leg paralysis (inability to walk and to move one or both legs) was first observed between 10 to 12 days of age in birds receiving no supplemental riboflavin. Besides leg paralysis, high mortality and poor growth were the main signs of riboflavin deficiency observed. A minimum requirement for growth of 3.6 mg of riboflavin/ kg of feed was determined using the broken-line technique. However, in order to prevent signs of leg paralysis, the minimum requirement of 4.6 mg riboflavin/kg of feed was suggested. Based on the maximum feed intake (834 g) observed for birds to reach maximum body weight (593 g) at 21 days of age, a minimum intake of approximately 6.5 ^g riboflavin/g body weight was needed for maximum performance. (Key words: riboflavin, broiler chick, requirements, corn-soybean diet)
RIBOFLAVIN REQUIREMENTS OF CHICKS TABLE 1. Composition of basal diet Component
Percent
Ingredients Yellow corn Soybean meal ( 4 8 % CP) Animal fat Limestone Dicalcium p h o s p h a t e (22.0% Ca; 18.5% P) Salt Microingredientsl DL-Methionine
1.75 .40 .50 .22
Calculated^
CP, % 22.0 Moisture, % Ether e x t r a c t , % 7.9 Sulfur a m i n o acids, % .93 Riboflavin, mg/kg 1.6 3,200 ME, kcal/kg
Analyzed^ 21.8 10.8 7.8 2.6
1 Supplied per kilogram of diet: 6,600 IU vitamin A; 2,200 ICU vitamin D3; 2.2 mg menadione dimethylpyrimidinol bisulfite; 39.6 mg niacin; 13.2 mg pantothenic acid; 499 mg choline chloride; 22 Mg vitamin B12; 125 mg ethoxyquin; 60 mg manganese; 50 mg iron; 6 mg copper; .198 mg cobalt; 1.1 mg iodine; 35 mg zinc.
Birds were housed for 21 days in Petersime battery brooders (Petersime Incubator Co., Gettysburg, OH) with raised wire floors. A 24-h constant fluorescent light schedule was maintained in the battery room. Feed and water were offered ad libitum. At the termination of each experiment, male and female chicks were weighed on a per pen basis. In Experiment 1 each bird was visually evaluated for leg disorders . Feed consumption was determined by pen. In order to fit the broken-line linear model, the following procedure was followed: first, an ANOVA for the linear regression (SAS, 1985) was determined on the experimental data; i.e., body weights at 21 days, feed conversion, and feed intake were plotted against mg of supplemental riboflavin in the diet. Second, a family of linear-plateau models as described by Anderson and Nelson (1975) was fitted to the data. The model with the minimum residual sum of squares was chosen as the most adequate brokenline model. The minumum requrement for growth was estimated as the intersection of the ascending line and the plateau. RESULTS AND DISCUSSION
2
National Research Council (1984) table values were used for calculated analysis. 3
Average values of four determinations (two for each basal diet), except for riboflavin, which was determined on a single sample per basal diet.
to AOAC (1984). Crystalline riboflavin was used as the riboflavin supplement (reagent grade, 96% purity, Fisher Scientific Company, Chemical Manufacturing Division, Fair Lawn, NJ).
As the treatment X experiment interactions for body weight and feed intake data were not significant (P = .94 and P = .18, respectively), the data from both experiments were combined (Table 2). Using the broken-line technique (Figure 1) to determine the minimum requirement for riboflavin of broiler chicks from 1 to 21 days of age, it was found that the relationship between body weight, y (grams), and riboflavin level, x (milligrams per kilogram), can be expressed as: y = 272.88 4- 307.64 x
TABLE 2. Performance of broiler chicks fed various levels of supplemental riboflavin from 1 to 21 days of age in a corn-soybean meal diet1 Supplemental riboflavin
Body weight
(mg/kg)
(g)
0
273 550 592 588 605 585
.9 2.0 2.8 3.6 4.4
± ± ± ± ± +
9.7 12.1 12.4 11.3 8.5 12.2
Feed intake
Feed conversion
Leg paralysis incidence 2
(g/bird)
(g feed/g weight)
(%)
485 794 839 828 842 825
1.80 1.45 1.42 1.40 1.39 1.42
100.0 15.9 7.8 0 0 0
± 15.3 ± 8.8 ± 12.3 ± 13.0 ± 9.1 ± 9.4
± ± ± ± ± ±
.06 .03 .02 .01 .02 .02
1
Combined data of Experiments 1 and 2; means and SEM, 16 pens/treatment.
2
Measured in the first experiment only (64 birds/treatment).
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
Analysis
54.56 36.00 5.50 1.07
795
796
RUIZ AND HARMS
age. Mortality at the zero level of riboflavin supplementation was 18.7%. Incidence of leg paralysis decreased considerably by addition of .9 and 2.0 mg riboflavin/kg basal diet. Not only the number of birds exhibiting leg problems decreased with increasing levels of riboflavin supplementation, but also the severity of the disorder. The term ' 'curled-toe paralysis" has not been used here to describe the leg paralysis observed in these experiments because the descriptions given by Norris et al. (1930, 1931) and Bethke et al. (1931), which subsequently were called by Stokstad and Manning (1938) "curled-toe paralysis," did not match the type of leg paralysis that was predominantly observed. At the zero level of riboflavin supplementation, leg paralysis was very severe and involved 100% of the birds, as already mentioned. No "curledtoe paralysis" was observed. When .9 mg supplemental riboflavin was added to the basal diet, there was a substantial decrease in the number of birds with leg problems. Only at this level of riboflavin supplemen-
ts
Z.O
2.5
3.0
3.5
t.O
4.5
S U P P l E I E I t U I I I O F L M M I IIC/KG
FIGURE 1. Broken-line model applied to the relationship between supplemental dietary riboflavin and body weight at 21 days of age. Ascending portion, y = 272.88 + 307.64 x. Plus sign = predicted equation; square = mean value. Bars = SEM.
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on November 15, 2014
where supplemental riboflavin was less than 2.0 mg/kg feed. The coefficient of determination value is defined here as: R2 = [TSS(S + H)-SSE(S + H)]/ TSS(S + H) where TSS = total sum of squares, SSE = sum of squares for error, and the letters S and H = the sloping and horizontal portions of the curve, respectively. The R2 for the brokenline model was .79. The intersection between the sloping line and the plateau was at 1.0 mg supplemental riboflavin/kg of diet. As the analyzed riboflavin content of the basal diets was 2.6 mg/kg (Table 1), the minimum riboflavin requirement for growth of broiler chicks to 21 days of age was estimated to be 3.6 mg/kg feed. Feed intake increased and feed conversion improved until a level of 2.0 mg supplemental riboflavin/kg feed was reached. The minimum requirement of 3.6 mg riboflavin/kg feed as determined by the broken-line technique is identical to the minimum requirement currently suggested by NRC (1984). This suggested requirement has remained almost unmodified since 1946 (NRC, 1946) after the work of several researchers. Norris et al. (1936) reported that chicks needed approximately 2.9 mg of riboflavin/kg feed in order to attain normal weight at 8 wk of age. Bethke and Record (1942) suggested a minimum of 2.5 mg/kg for growth but more than 3.0 mg riboflavin/kg feed for complete protection against leg paralysis (curled toe paralysis). Bird et al. (1946) indicated that 2.75 to 3.25 mg riboflavin/kg feed was adequate for growth and even less was needed for complete prevention of leg paralysis (curled toe paralysis). Although White Leghorn chicks were used by most of the aforementioned authors, Bolton (1944) determined the riboflavin requirement of the White Wyandotte chick and reported that 3.0 mg riboflavin/kg feed was the minimum requirement for optimum growth to 6 wk of age, and 3.6 mg for the prevention of leg paralysis (curled toe paralysis). The signs of deficiency observed when the corn-soybean meal diet without supplemental riboflavin was fed to broiler chicks from 1 to 21 days of age were severe leg paralysis (inability to walk, and inability to move one or both legs) as illustrated in Figure 2, high mortality, and poor growth. In the first experiment in which quantification of incidence of leg paralysis was carried out, 100% of the surviving birds were paralyzed at 21 days when no riboflavin was added to the basal diet. However, leg paralysis was first observed between 10 to 12 days of
RIBOFLAVIN REQUIREMENTS OF CHICKS
797
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FIGURE 2. Riboflavin deficiency in broiler chicks at 21 days of age. A, the bird at left was fed a corn-soybean meal diet without supplemental riboflavin. This chicks exhibited the predominant type of paralysis observed at the zero level of riboflavin supplementation. The bird at right was fed the same basal diet, but adequate in riboflavin. Both birds were females. B, same as A, but male chicks.
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RUIZ AND HARMS
imately 1 mg of riboflavin/kg feed; therefore, a total of 3.6 mg/kg feed is adequate for maximum growth. It is possible that the requirement may be slightly higher in the event that the response curve is curvilinear near the point of maximum growth. However, as already mentioned, at 2.0 mg supplemental riboflavin only a slight leg weakness was observed in five birds out of 64. At this level also, feed intake was maximized and feed efficiency was improved. Consequently, it is suggested that at least 4.6 mg of riboflavin/kg feed are needed for maximum growth and prevention of leg paralysis in broiler chicks from 1 to 21 days of age. As the average feed intake per bird (total feed intake during the 21-day experimental period) maximized at 834 g, and the body weight plateau was 593 g, a minimum intake of approximately 6.5 |xg riboflavin/g body weight was needed for maximum performance. ACKNOWLEDGMENTS
Appreciation is expressed to Ramon C. Littell and Steve B. Linda for their assistance in the statistical analysis. REFERENCES Anderson, R. L., and L. A. Nelson, 1975. A family of models involving intersecting straight lines and concomitant experimental designs useful in evaluating response to fertilizer nutrients. Biometrics 31:303-318. Association of Official Analytical Chemists, 1984. Official Methods of Analysis. 14th ed. Association of Official Analytical Chemists, Arlington, VA. Bethke, R. M., and P. R. Record, 1942. The relation of riboflavin to growth and curled-toe paralysis in chicks. Poultry Sci. 21:147-154. Bethke, R. M., P. R. Record, and D. C. Kennard, 1931. A type of nutritional leg paralysis affecting chicks. Poultry Sci. 10:355-368. Bird, F. H., V. S. Asmundson, F. H. Kratzer, and S. Lepkovsky, 1946. The comparative requirements of chicks and turkey poults for riboflavin. Poultry Sci. 25:47-51. Bolton, W., 1944. The riboflavin requirement of the White Wyandotte chick. J. Agric. Sci. 34:198-206. Bolton, W., 1947. The riboflavin requirement of the White Wyandotte chick. II. Pure crystalline riboflavin as the vitamin supplement. J. Agric. Sci. 37: 316-322. Gries, C. L., and M. L. Scott, 1972. The pathology of thiamin, riboflavin, pantothenic acid and niacin deficiencies in the chick. J. Nutr. 102:1269-1286. Heuser, G. F., 1955. Feeding Poultry, 2nd ed. John Wiley and Sons, Inc., New York, NY. Heuser, G. F., H. S. Wilgus, and L. C. Norris, 1938. The quantitative vitamin-G requirement of chicks. Poultry Sci. 17:105-108. Johnson, W. D., 1976. A study of the pathogenesis of the peripheral neuropathy associated with riboflavin deficiency in the chicken. Diss. Abstr. 378:1136-1137.
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tation did the predominant paralysis observed appear similar to the curled-toe description. Birds rested on their hocks, with their toes curled. Movement was difficult; however, they were able to reach feed and water. But in quantitative terms 15.9% of the birds receiving .9 mg of supplemental riboflavin were exhibiting leg paralysis. At 2.0 mg of supplemental riboflavin/kg feed (4.6 mg total riboflavin/kg feed) only five birds out of 64 (7.8%) displayed a slight leg difficulty, which was characterized by slight shaking of the legs for a few seconds when standing up. No birds showed signs of curled-toe paralysis. The leg paralysis described above has been reported by Wyatt et al. (1973), who conducted several experiments with broiler chicks of three different strains with the objective of defining the signs of riboflavin deficiency. These authors indicated that curled-toe paralysis was not the predominant sign of riboflavin deficiency in broiler chicks. Johnson (1976) indicated that partial or complete paralysis was observed in chicks fed a diet containing 1.65 mg riboflavin/ kg diet, between 12 to 20 days of age, and Jortner et al. (1985), working with a diet containing 1.8 mg riboflavin/kg feed, found that broiler chicks showed neurological signs as early as 7 days of age that included weakness, paralysis, and on occasion curled toes. Although Gries and Scott (1972) reported 20% mortality of birds fed a basal diet containing .3 mg of riboflavin/kg diet, these authors did not observe paralysis in the surviving birds. Gries and Scott (1972) did not observe the enlargement of the sciatic nerve in severely riboflavin deficient birds as described by Phillips and Engel (1938). However, Jortner et al. (1985) reported that the sciatic nerve of riboflavin-deficient birds had a demyelinating neuropathy at 15 days of age. It is hypothesized that the severe paralysis observed is related to the growth rate of the modern broiler chicken. The latter grows faster than the White Leghorn and crossbred chicks of approximately 50 and 40 yr ago. As a faster growth rate is proportionally correlated the greater feed intake, it appears that the riboflavin requirement, expressed as concentration of the diet, remains almost the same as 40 yr ago. However, beacuse feed efficiency is much higher today, the deficiency of riboflavin is much more critical and becomes more severe than before. It is clear from the broken-line model that growth maximized with the addition of approx-
RIBOFLAVIN REQUIREMENTS OF CHICKS
Heiman, and G. F. Heuser, 1936. The vitamin-G requirement of poultry. Cornell Univ. Agric. Exp. Sta. Bull. 660. Ithaca, NY. Phillips, P. H., and R. W. Engel, 1938. The histopathology of neuromalacia and "curled-toe" paralysis in the chick fed low riboflavin diets. J. Nutr. 16:451-463. SAS, 1985. SAS User's Guide: Statistics. SAS Institute Inc., Cary, NC. Stokstad, E.L.R., and P.D.V. Manning, 1938. The effect of riboflavin on the incidence of curled toe paralysis in chicks. J. Nutr. 16:279-283. Titus, H. W., and J. C. Fritz, 1971. The Scientific Feeding of Chickens. 5th ed. The Interstate Printers and Publishers, Inc., Danville, EL. Wyatt, R. D., H. T. Ting, W. E. Donaldson, and P. B. Hamilton, 1973. A new description of riboflavin deficiency syndrome in chickens. Poultry Sci. 52:237244.
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(Abstr.) Jortner, B. S., J. A. Cherry, andM. Ehrich, 1985. Peripheral neuropathy of dietary riboflavin deficiency in chickens. J. Neuropathol. & Exp. Neurol. 43:342. (Abstr.) National Research Council, 1947. Recommended nutrient allowances for poultry. Mimeographed release. Pages 1300-1305 in: Poultry Nutrition. W. R. Ewing, ed. 3rd ed. South Pasadena, CA. National Research Council, 1984. Nutrient Requirements of Poultry, 8th ed. Natl. Acad. Press, Washington, DC. Norris, L. C , G. F. Heuser, and H. S. Wilgus, Jr., 1930. Is the chief value of milk for feeding poultry due to the presence of a new vitamin? Poultry Sci. 9:133-140. Norris, L. C , G. F. Heuser, and H. S. Wilgus, Jr., 1931. The occurence in chicks of a paralysis of nutritive origin. Poultry Sci. 10:93-97. Norris, L. C , H. S. Wilgus, Jr., A. T. Ringrose, V.
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