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The Effect of Early Protein Restriction (Zero to Eight Weeks) on Skeletal Development in Turkey Toms from Two to Eighteen Weeks1
The Effect of Early Protein Restriction (Zero to Eight Weeks) on Skeletal Development in Turkey Toms from Two to Eighteen Weeks1 K. A. TURNER2 and M. S. LILBURN3 Department of Poultry Science, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691-4096
1992 Poultry Science 71:1680-1686
INTRODUCTION Leg-associated problems are of increasing concern to the turkey industry. Turkey breeders have improved the growth potential and body conformation of commercial toms, but these improvements have not necessarily affected all carcass parts proportionately. Lilburn and Nestor (1991) reported that at 12 and 16 wk, toms from a randombred line (RBC2) were approximately 30% lighter than toms from
Received for publication February 14, 1992. Accepted for publication June 5, 1992. Salaries and research support provided by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University. Manuscript Number 37-92. 2 Current address: Animal Science Department, Iowa State University, Ames, IA 50011. 3 To whom correspondence should be addressed.
a growth-selected subline (F line), but there were rninimal differences in tibia and femur length. At 16 wk, however, the defatted tibiae were 23% heavier in F line toms as compared with those of toms from the RBC2 line (Nestor et at, 1988). In studies with humans and rats, highprotein diets have been shown to influence calcium metabolism by increasing glomerular filtration and decreasing renal tubule reabsorption (Bell et ah, 1975; Chu et al., 1975; Kerstetter and Allen, 1990). Increased calcium excretion associated with high-protein diets will increase bone matrix turnover and hamper normal bone formation in rats (Weiss et al., 1981). Lowprotein diets have also been associated with osteoporosis and other skeletal abnormalities in rats (El-Maraghi et al., 1965). In commercial broilers and turkeys, manipulation of dietary protein and amino acids has also been studied with
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ABSTRACT Turkey toms were fed protein- and lysine-deficient diets or protein- and lysine-adequate diets from 0 to 4 and 5 to 8 wk and similar diets from 9 to 18 wk. Beginning at 2 wk of age and at approximate 2-wk intervals thereafter, the length and width of the right tibia were measured in nine toms per treatment. The length and width of the femur were measured beginning at 8 wk. Three tibiae that were close to the average length for each age and treatment were selected for ashing. The top 25% (epiphyseal) and middle 10% (diaphyseal) segments from each of these bones were fat-extracted prior to ashing. Mean length of the tibia continued to increase throughout tine experiment whereas tibia width reached a plateau at 16 wk. Femur length also continued to increase throughout the study whereas there were no significant changes in femur width after 16 wk. Compared with the control diet, the diet deficient in protein and lysine resulted in a significant decrease in tibia and femur width at all ages. There were no dietary effects on tibia length at 16 and 18 wk, however. There were no significant dietary effects on femur length after 14 wk. There were significant age effects but no significant dietary effects on epiphyseal or diaphyseal bone ash. Epiphyseal bone ash increased from 41 to 54% over the course of the study whereas diaphyseal bone ash increased only from 59 to 64%. (Key words: turkey, tibia, length, width, bone ash)
SKELETAL GROWTH IN TURKEY TOMS
kitchener, ON, N2B 3E9, Canada.
tein levels were at 70% or less of the NRC (1984) requirements. These authors cited the report by Stevens and Salmon (1988) and suggested that the higher protein diets may have had adverse effects on bone mineralization, although no bone ash data were presented. Toms fed the protein-restricted diets did not catch up to those fed the control diet from 1 to 6 wk, and carcass traits were likewise still negatively affected at 20 wk. There is little data in the literature on age and treatment effects on skeletal growth in commercial turkeys. Walser et al. (1982) reported on tibia and femur growth (length) from 8 to 39 wk in five commercial turkey strains relative to the development of tibial dyschondroplasia. Hester et al. (1986) and Klingensmith et al. (1986) reported tibia length, width, and ash data from toms and hens exposed to different lighting treatments. Both sets of data, however, were collected during the latter stages of growth. The data of Nestor et al. (1988) suggests that large differences in BW are associated with changes in appositional (diaphyseal) bone growth with no effects on linear (epiphyseal) bone growth. This observation warranted a closer look at these specific anatomical regions of the growing bone. The objectives of the current study, therefore, were to characterize gross changes in the length, width, and ash of long bones during the standard growing period for commercial toms and to study the relationship between an early period of protein deficiency and skeletal development throughout the growing period. MATERIALS AND METHODS Hatching and Brooding
Commercial hatching eggs were purchased from Hybrid Inc.4 At hatch, the poults were sexed and wing-banded. There were approximately 550 toms at the start of the study. From 0 to 2 wk, the toms were brooded in six floor pens. The toms in half the pens (n = 3) were fed either a control (C) or protein-deficient (PD) starter diet. At 2 wk, the toms in each dietary treatment were distributed randomly over an additional six
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
respect to the effect on leg-associated disorders. Low-protein starter diets have been used to decrease early growth and minimize leg problems in broilers grown to heavy roaster weights (Hulan et al, 1980; Hulan and Proudfoot, 1981). Summers et al. (1984) reported that high levels of dietary protein might have a negative effect on leg problems in broiler chickens and there appeared to be an interaction with calcium level. Skinner et al. (1991) reported that diets low in amino acids (80 or 90% of the levels recommended by Thomas et al, 1986) increased bone ash compared with diets containing higher levels of amino acids (100 and 110% of the levels recommended by Thomas et al, 1986). The effects were more pronounced in diets containing .5% compared with 1.0% calcium. Tibia length was significantly decreased only in the 80% amino acid diet, and there were no treatment effects on tibia width. Stevens and Salmon (1988) reported that diets containing 34 or 39% dietary protein significantly increased the incidence of leg disorders in turkeys by 2 wk of age and this continued through 18 wk. There was also a significant decrease in bone ash associated with the higher protein diets. These levels of protein, however, are far in excess of National Research Council (NRC, 1984) requirements or levels commonly used by commercial nutritionists. Small strains of turkeys have been reported to undergo compensatory growth after early growth restriction and reach the same BW as conventionally reared toms (Aukland and Morris, 1971; Aukland, 1972; Moran, 1981). Ferket and Sell (1989) fed low-protein diets during the initial stages of growth (1 to 6 wk) followed by standard diets from 7 to 18 wk. Their objective was to decrease the incidence of leg-associated problems in growing toms and to study the growth characteristics of toms during the catch-up period from 7 to 18 wk. Toms fed the lowprotein diets did have a lower incidence of leg weakness at 20 wk, but the only significant differences occurred when pro-
1681
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TURNER AND LILBURN
pens so that each diet was fed subsequently to a total of nine replicate pens. From 2 to 18 wk, the floor space in each pen was approximately .3 m 2 per torn.
These sections were cut from each bone with a small table saw. The three epiphyseal sections and the three diaphyseal sections corresponding to a treatment and age were subsequently fat extracted prior to ashing.
Experimental Diets
Bone Measurements Beginning at 2 wk of age and at 14- to 16-day intervals thereafter, nine toms from each dietary treatment were chosen randomly for carcass and bone measurements. At 2 wk, this represented three randomly selected toms from each replicate pen. At all subsequent ages, one torn per replicate pen was selected randomly. There were no preselection criteria (i.e., mean BW for treatment or pen) used prior to the random sampling of toms from each pen and all selected toms had no visible leg abnormalities. Each torn was weighed, killed by cervical dislocation, and the right tibia (drum) was dissected from the carcass. Much of the adhering tissue was removed at the time of dissection, but each tibia was subsequently immersed in boiling water for 15 min to complete tissue removal. From 8 through 18 wk, the femur (thigh) was also removed for length and width measurements. The length and, at the calculated midpoint, the width of each bone was measured. Three bones per treatment that had the average length for that age and treatment were selected for ashing. An epiphyseal section (top 25%) and a diaphyseal section (middle 10%) of each bone were determined from length measurements.
Statistical Analysis The data were analyzed using the General Linear Models procedure of SAS® software (SAS Institute, 1985). The main effects tested for each variable were age, diet, and the interaction of diet and age. The 5% level of probability was considered significant. RESULTS The PD diet significantly decreased BW by 2 wk of age (Figure 1). These differences were evident for the duration of the study. The PD diet significantly decreased tibia length from 4 through 12 wk compared with the C diet (Figure 2). There were no significant diet effects at 14,16, or 18 wk. Increases in tibia length with age were significant throughout the study. Tibia width was also significantly reduced by the PD diet beginning at 2 wk, and the dietary effects were significant for the remainder of the study (Figure 3). There was no further increase in tibia width after 16 wk. There were no diet effects on femur length after 14 wk, whereas femur length continued to increase throughout the study (Figure 4). Femur width was significantly decreased by the PD dietary treatment throughout the study whereas there were no significant age effects after 14 wk (Figure 5). There were no significant diet effects on tibia epiphyseal or diaphyseal ash (Figures 6 and 7). There were significant increases in percentage ash with age in both bone segments, although the increases in the epiphyseal segment (from approximately 41 to 42% at 2 wk to 54% at 18 wk) were far greater than the diaphyseal segments, which increased from 59% at 2 wk to 64% at 18 wk. DISCUSSION The toms fed the PD diet had significantly reduced BW at young ages and
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From 0 to 4 wk, toms were fed each of two diets. The C diet was formulated to NRC (1984) specifications for protein and essential amino acids (Table 1). An isocaloric, lower protein starter diet (PD) was formulated to 90% of the NRC (1984) recommended protein level and 80% of the NRC (1984) recommended lysine level. From 5 to 8 wk, the PD diet was formulated to the NRC (1984) recommended protein level but only 95% of the NRC (1984) recommended lysine level. From 9 to 18 wk, both groups were fed diets formulated to the NRC (1984) protein and amino acid specifications.
.35 1.05 1.20 .20
.40 1.00 1.40
.10 .10 2.00
29.3 28.6 2,817 1.65 1.06
6.00
6.00
2,809 1.31 1.07
25.6
2.00
5.00
50.20 34.00
40.00 5.00
44.00
Control
25.7 24.7 2,897 1.53 .93
21 22 2 1
1
25.5 24.6 2,895 1.22 .93
.05
.05 .40 2.00
1
2
.30 .50 .50
.30 .50 .50
2
30
61
8 to 12 w
2.00
8.00
7.50
53.15 28.00
(—1
IO/.\
Age
7.75
. . .
7.50
53.00 28.00
Control
4 to 8 wk PD
2
*PD = protein-deficient diet. The premix contains (in kilograms per 100 kg of diet): ground com, 54.0; amprolium (25%), 2.5; selenium premix (200 m (60%), 6.00; vitamin premix, 25.00; trace mineral premix, 5.00. 3 The vitamin premix contributed the following per kilogram of diet: vitamin A, 8,745 IU; cholecalciferol, 3,745 ICU; vitam 2.91 mg; thiamine HCl, 2.2 mg; riboflavin, 6.6 mg; niacin, 99 mg; pantothenic acid, 15.4 mg; folic acid, 1.2 mg; pyridoxin ethoxyquin, 113.5 mg. 4 The trace mineral premix contributed the following per kilogram of diet zinc oxide (72% Zn), 147 mg; manganous oxid mg; ferrous sulfate monohydrate (31% Fe), 72 mg; and potassium iodide, 1.5 mg.
Ground corn Soybean meal (44% CP) Soybean meal (49% CP) Meat plus bone meal (50% CP) Fishmeal, menhaden Corn gluten meal Wheat middlings Animal-vegetable fat Salt Ground limestone Dicalcium phosphate Defluorinated phosphate DL-methionine L-lysine Premix2A4 Dietary analysis Crude protein Calculated Analyzed ME, kcal/kg Lysine TSAA
Ingredients and analysis
0 to 4 wk PD
TABLE 1. The composition of experimental diets1
ded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
1684
TURNER AND LLBURN control
a
~ontro
Def~c~ent
Defrc~ent
Age lwkl
never caught up with those toms fed the C diet. This confirms the previous report of Ferket and Sell (1989). The results of Ferket and Sell (1989) and those from the present study are not consistent, however, with those of Oju et al. (1988a,b). Oju et al. (1988a,b) reported that protein restriction from 0 to 6 wk did not significantly affect BW in toms and hens after 16 wk (P < .088) and 17 wk (P < .408), respectively. One factor contributing to the discrepancy between experimental results is overall growth rate, which was less in the study gy Oju et al. (1988a,b) compared with thk present results and those of Ferket and Sell (1989). This required less "catching up" by the hens and toms fed the restricted diets. The tibia length and tibia width data support the conclusion of Lilburn and Nestor (1991) that linear (length) and appositional (width) bone development are differentially regulated. Results from that study and a previous report by Nestor et al. (1988) showed that slow- and fast-growing turkeys have similar bone lengths at 16 wk, but defatted bone weight is increased almost 25% in the fastgrowing strain. In the present study, the PD treatment decreased BW and tibia width 25 and 22%, respectively, at 4 wk compared with C toms, whereas tibia length was only decreased 11%. By 14 wk
FIGURE 2. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on tibia length in commercial toms. There were significant age effects on tibia length throughout the experiment. Asterisks indicate that the deficient diet resulted in a significant decrease in tibia length (P 1.05) from 4 to 12 wk.
of age, BW of PD toms was 14% less than that of C toms, whereas tibia width was only 5% less and no difference was observed for tibia length. The lesser effect that protein deficiency had on skeletal development compared with BW would increase relative skeletal support in toms fed the PD diets. This has been suggested by Nestor et al. (1988) as one mechanism by which alterations in skeletal growth might decrease the incidence of leg weakness in heavy toms. These results, together with those of Lilburn and Nestor (1991),
Def8cnent
~onlrol
20 r
,
1
f,
8
li)
12
l4
16
18
Age lwk)
FIGURE 3. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on tibia width in commercial toms. Asterisks indicate that the deficient diet significantly decreased tibia width (P 2 .05) at all ages. There were no age effects after 16 wk.
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
FIGURE 1. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on body weight in commercial toms. Asterisks indicate that the deficient diet resulted in a significant decrease in BW (P I.05) at all ages compared with a control diet formulated to National Research Council (1984) protein and amino acid specifications.
Age lwkl
SKELETAL GROWTH IN TURKEY TOMS control
- Control
~ e r ~ ~ , o ? t
.----
Deftctent
I
A g e (wkl
Age (wkl
FIGURE 6. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on epiphyseal bone ash in commercial toms. There were no significant dietary protein effects ( P t .05).
toms fed lower protein diets, as suggested by Stevens and Salmon (1988) and Ferket also suggest that knowledge of the growth and Sell (1989). The Stevens and Salmon and development of the diaphyseal bone (1988) study was based on experimental segment may provide more insight into diets that contained protein levels far in those factors contributing to leg weakness excess of NRC (1984) recommendations. in poultry than information on linear or Extreme caution is always needed when extrapolating the results from this type of whole bone growth. The lack of any significant diet effects study to more practical situations. The on tibia epiphyseal or diaphyseal ash starting diets in the Stevens and Salmon demonstrates that impaired bone minerali- (1988) study also contained a substantial zation is not contributing to the decreased quantity of supplemental dietary fat and incidence of leg weakness observed in the bones were ashed without prior fat extraction. The protein effects on bone ash at 2 wk were minimal (P < .I), so the best
control
Def~c~ent
- Control
-
B
10
12
in
16
..---
LOW Prolean
ie
Age lwki
FIGURE 5. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on femur width in commercial toms. Asterisks indicate that the deficient diet significantly decreased femur width ( P < .05) at all ages. There were no significant age effects after 16 wk.
FIGURE 7. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on diaphyseal bone ash in growing toms. There were no significant dietary protein effects ( P t .05).
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
FIGURE 4. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on femur length in commercial toms. Asterisks indicate that the deficient diet reduced femur length ( P < .05) at 8 to 14 wk but there were no significant diet effects on femur length ( P t .05) at 16 and 18 wk of age. There were significant age effects ( P < .05) throughout the study.
1686
TURNER AND LILBURN
conclusion from the report of Stevens and Salmon (1988) is that NRC (1984) recommendations for protein and calcium are adequate for maximal growth and bone ash. REFERENCES
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
Aukland, J. N., 1972. Compensatory growth in turkeys: Practical implications and limitations. World's Poult. Sci. J. 28:291-300. Aukland, J. N., and T. R. Morris, 1971. Compensatory growth after undernutrition in market turkeys: Effect of low protein feeding and realimentation on body composition. Br. Poult. Sci. 12:137-150. Bell, R. R., D. T. Engleman, T. L. Sie, and H. H. Draper, 1975. Effect of a high protein intake on calcium metabolism in the rat. J. Nutr. 105: 475-483. Chu, J. Y., M. D. Margen, and F. S. Costa, 1975. Studies in calcium metabolism. II. Effects of low calcium and variable protein intake on human calcium metabolism. Am. J. Clin. Nutr. 28: 1028-1035. El-Maraghi, N.R.H., B. S. Piatt, and R.J.C. Stewart, 1965. The effect of the interaction of dietary protein and calcium on the growth and maintenance of the bones of young, adult, and aged rats. Br. J. Nutr. 19:491-509. Ferket, P. R., and J. L. Sell, 1989. Effect of severity of early protein restriction on large turkey toms. 1. Performance characteristics and leg weakness. Poultry Sci. 68:676-686. Hester, P. Y., I. C. Peng, R. L. Adams, E. J. Furumoto, J. E. Larsen, P. M. Klingensmith, O. A. Pike, and W. J. Stadelman, 1986. Comparison of two lighting regimens and drinker cleaning programmes on the performance and incidence of leg abnormalities in turkey males. Br. Poult. Sci. 27:63-73. 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., F. G. Proudfoot, D. Ramey, and K. B. McRae, 1980. Influence of genotype and diet on general performance of chickens reared to roaster weight. Poultry Sci. 59:748-757. Kerstetter, J. E., and L. H. Allen, 1990. Dietary protein increases urinary calcium. J. Nutr. 120:134-136. Klingensmith, P. M , P. Y. Hester, R. G. Elkin, and C. R. Ward, 1986. Relationship of high intensity step-up lighting to bone ash and growth plate
closure of the tarso-metatarsus in turkeys. Br. Poult. Sci. 27:487-492. Lilburn, M. S., and K. E. Nestor, 1991. Body weight and carcass development in different lines of turkeys. Poultry Sci. 70:2223-2231. Moran, E. T., Jr., 1981. Early protein nutrition, compensatory growth, and carcass quality of broiler-type torn turkeys. Poultry Sci. 60: 401-106. National Research Council, 1984. Nutrient Requirements of Poultry. 8th rev. ed. National Academy Press, Washington, DC. Nestor, K. E., W. L. Bacon, G. B. Havenstein, Y. M. Saif, and P. A. Renner, 1988. Carcass traits of turkeys from lines selected for increased growth rate or increased shank width. Poultry Sci. 67: 1660-1667. Oju, E. M , P. E. Waibel, and S. L. Noll, 1988a. Early protein undernutrition and subsequent realimentation in turkeys. 1. Effect on performance and body composition. Poultry Sci. 67: 1750-1759. q u , E. M , P. E. Waibel, and S. L. Noll, 1988b. Early protein undernutrition and subsequent realimentation in turkeys. 2. Effect on weights and proportions of organs and tissues. Poultry Sci. 67:1760-1769. SAS Institute, 1985. SAS® User's Guide: Statistics. Version 5 Edition. SAS Institute Inc., Cary, NC. Skinner, J. T., J. N. Beasley, and P. W. Waldroup, 1991. Effects of dietary amino acid levels on bone development in broiler chickens. Poultry Sci. 70:941-946. Stevens, V. I., and R. E. Salmon, 1988. Effects of dietary protein on leg disorders in turkeys. Nutr. Rep. Int. 38:915-925. Summers, J. D., H. Shen, S. Leeson, and R. J. Julian, 1984. Influence of vitamin deficiency and level of dietary protein on the incidence of leg problems in broiler chicks. Poultry Sci. 63: 1115-1119. Thomas, O. P., A. I. Zuckerman, M. Farran, and C. B. Tamplin, 1986. Updated amino acid requirements of broilers. Pages 79-85 in: Proceedings of the Maryland Nutrition Conference, University of Maryland, College Park, MD. Walser, M. M., F. L. Cherms, and H. E. Dziuk, 1982. Osseous development and tibial dyschondroplasia in five lines of turkeys. Avian Dis. 26: 265-272. Weiss, R. E., A. Gorn, S. Dux, and M. E. Nimni, 1981. Influence of high protein diets on cartilage and bone formation in rats. J. Nutr. 111:804-816.
1992 Poultry Science 71:1680-1686
INTRODUCTION Leg-associated problems are of increasing concern to the turkey industry. Turkey breeders have improved the growth potential and body conformation of commercial toms, but these improvements have not necessarily affected all carcass parts proportionately. Lilburn and Nestor (1991) reported that at 12 and 16 wk, toms from a randombred line (RBC2) were approximately 30% lighter than toms from
Received for publication February 14, 1992. Accepted for publication June 5, 1992. Salaries and research support provided by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University. Manuscript Number 37-92. 2 Current address: Animal Science Department, Iowa State University, Ames, IA 50011. 3 To whom correspondence should be addressed.
a growth-selected subline (F line), but there were rninimal differences in tibia and femur length. At 16 wk, however, the defatted tibiae were 23% heavier in F line toms as compared with those of toms from the RBC2 line (Nestor et at, 1988). In studies with humans and rats, highprotein diets have been shown to influence calcium metabolism by increasing glomerular filtration and decreasing renal tubule reabsorption (Bell et ah, 1975; Chu et al., 1975; Kerstetter and Allen, 1990). Increased calcium excretion associated with high-protein diets will increase bone matrix turnover and hamper normal bone formation in rats (Weiss et al., 1981). Lowprotein diets have also been associated with osteoporosis and other skeletal abnormalities in rats (El-Maraghi et al., 1965). In commercial broilers and turkeys, manipulation of dietary protein and amino acids has also been studied with
1680
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
ABSTRACT Turkey toms were fed protein- and lysine-deficient diets or protein- and lysine-adequate diets from 0 to 4 and 5 to 8 wk and similar diets from 9 to 18 wk. Beginning at 2 wk of age and at approximate 2-wk intervals thereafter, the length and width of the right tibia were measured in nine toms per treatment. The length and width of the femur were measured beginning at 8 wk. Three tibiae that were close to the average length for each age and treatment were selected for ashing. The top 25% (epiphyseal) and middle 10% (diaphyseal) segments from each of these bones were fat-extracted prior to ashing. Mean length of the tibia continued to increase throughout tine experiment whereas tibia width reached a plateau at 16 wk. Femur length also continued to increase throughout the study whereas there were no significant changes in femur width after 16 wk. Compared with the control diet, the diet deficient in protein and lysine resulted in a significant decrease in tibia and femur width at all ages. There were no dietary effects on tibia length at 16 and 18 wk, however. There were no significant dietary effects on femur length after 14 wk. There were significant age effects but no significant dietary effects on epiphyseal or diaphyseal bone ash. Epiphyseal bone ash increased from 41 to 54% over the course of the study whereas diaphyseal bone ash increased only from 59 to 64%. (Key words: turkey, tibia, length, width, bone ash)
SKELETAL GROWTH IN TURKEY TOMS
kitchener, ON, N2B 3E9, Canada.
tein levels were at 70% or less of the NRC (1984) requirements. These authors cited the report by Stevens and Salmon (1988) and suggested that the higher protein diets may have had adverse effects on bone mineralization, although no bone ash data were presented. Toms fed the protein-restricted diets did not catch up to those fed the control diet from 1 to 6 wk, and carcass traits were likewise still negatively affected at 20 wk. There is little data in the literature on age and treatment effects on skeletal growth in commercial turkeys. Walser et al. (1982) reported on tibia and femur growth (length) from 8 to 39 wk in five commercial turkey strains relative to the development of tibial dyschondroplasia. Hester et al. (1986) and Klingensmith et al. (1986) reported tibia length, width, and ash data from toms and hens exposed to different lighting treatments. Both sets of data, however, were collected during the latter stages of growth. The data of Nestor et al. (1988) suggests that large differences in BW are associated with changes in appositional (diaphyseal) bone growth with no effects on linear (epiphyseal) bone growth. This observation warranted a closer look at these specific anatomical regions of the growing bone. The objectives of the current study, therefore, were to characterize gross changes in the length, width, and ash of long bones during the standard growing period for commercial toms and to study the relationship between an early period of protein deficiency and skeletal development throughout the growing period. MATERIALS AND METHODS Hatching and Brooding
Commercial hatching eggs were purchased from Hybrid Inc.4 At hatch, the poults were sexed and wing-banded. There were approximately 550 toms at the start of the study. From 0 to 2 wk, the toms were brooded in six floor pens. The toms in half the pens (n = 3) were fed either a control (C) or protein-deficient (PD) starter diet. At 2 wk, the toms in each dietary treatment were distributed randomly over an additional six
Downloaded from http://ps.oxfordjournals.org/ at University of Manitoba on June 10, 2015
respect to the effect on leg-associated disorders. Low-protein starter diets have been used to decrease early growth and minimize leg problems in broilers grown to heavy roaster weights (Hulan et al, 1980; Hulan and Proudfoot, 1981). Summers et al. (1984) reported that high levels of dietary protein might have a negative effect on leg problems in broiler chickens and there appeared to be an interaction with calcium level. Skinner et al. (1991) reported that diets low in amino acids (80 or 90% of the levels recommended by Thomas et al, 1986) increased bone ash compared with diets containing higher levels of amino acids (100 and 110% of the levels recommended by Thomas et al, 1986). The effects were more pronounced in diets containing .5% compared with 1.0% calcium. Tibia length was significantly decreased only in the 80% amino acid diet, and there were no treatment effects on tibia width. Stevens and Salmon (1988) reported that diets containing 34 or 39% dietary protein significantly increased the incidence of leg disorders in turkeys by 2 wk of age and this continued through 18 wk. There was also a significant decrease in bone ash associated with the higher protein diets. These levels of protein, however, are far in excess of National Research Council (NRC, 1984) requirements or levels commonly used by commercial nutritionists. Small strains of turkeys have been reported to undergo compensatory growth after early growth restriction and reach the same BW as conventionally reared toms (Aukland and Morris, 1971; Aukland, 1972; Moran, 1981). Ferket and Sell (1989) fed low-protein diets during the initial stages of growth (1 to 6 wk) followed by standard diets from 7 to 18 wk. Their objective was to decrease the incidence of leg-associated problems in growing toms and to study the growth characteristics of toms during the catch-up period from 7 to 18 wk. Toms fed the lowprotein diets did have a lower incidence of leg weakness at 20 wk, but the only significant differences occurred when pro-
1681
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TURNER AND LILBURN
pens so that each diet was fed subsequently to a total of nine replicate pens. From 2 to 18 wk, the floor space in each pen was approximately .3 m 2 per torn.
These sections were cut from each bone with a small table saw. The three epiphyseal sections and the three diaphyseal sections corresponding to a treatment and age were subsequently fat extracted prior to ashing.
Experimental Diets
Bone Measurements Beginning at 2 wk of age and at 14- to 16-day intervals thereafter, nine toms from each dietary treatment were chosen randomly for carcass and bone measurements. At 2 wk, this represented three randomly selected toms from each replicate pen. At all subsequent ages, one torn per replicate pen was selected randomly. There were no preselection criteria (i.e., mean BW for treatment or pen) used prior to the random sampling of toms from each pen and all selected toms had no visible leg abnormalities. Each torn was weighed, killed by cervical dislocation, and the right tibia (drum) was dissected from the carcass. Much of the adhering tissue was removed at the time of dissection, but each tibia was subsequently immersed in boiling water for 15 min to complete tissue removal. From 8 through 18 wk, the femur (thigh) was also removed for length and width measurements. The length and, at the calculated midpoint, the width of each bone was measured. Three bones per treatment that had the average length for that age and treatment were selected for ashing. An epiphyseal section (top 25%) and a diaphyseal section (middle 10%) of each bone were determined from length measurements.
Statistical Analysis The data were analyzed using the General Linear Models procedure of SAS® software (SAS Institute, 1985). The main effects tested for each variable were age, diet, and the interaction of diet and age. The 5% level of probability was considered significant. RESULTS The PD diet significantly decreased BW by 2 wk of age (Figure 1). These differences were evident for the duration of the study. The PD diet significantly decreased tibia length from 4 through 12 wk compared with the C diet (Figure 2). There were no significant diet effects at 14,16, or 18 wk. Increases in tibia length with age were significant throughout the study. Tibia width was also significantly reduced by the PD diet beginning at 2 wk, and the dietary effects were significant for the remainder of the study (Figure 3). There was no further increase in tibia width after 16 wk. There were no diet effects on femur length after 14 wk, whereas femur length continued to increase throughout the study (Figure 4). Femur width was significantly decreased by the PD dietary treatment throughout the study whereas there were no significant age effects after 14 wk (Figure 5). There were no significant diet effects on tibia epiphyseal or diaphyseal ash (Figures 6 and 7). There were significant increases in percentage ash with age in both bone segments, although the increases in the epiphyseal segment (from approximately 41 to 42% at 2 wk to 54% at 18 wk) were far greater than the diaphyseal segments, which increased from 59% at 2 wk to 64% at 18 wk. DISCUSSION The toms fed the PD diet had significantly reduced BW at young ages and
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From 0 to 4 wk, toms were fed each of two diets. The C diet was formulated to NRC (1984) specifications for protein and essential amino acids (Table 1). An isocaloric, lower protein starter diet (PD) was formulated to 90% of the NRC (1984) recommended protein level and 80% of the NRC (1984) recommended lysine level. From 5 to 8 wk, the PD diet was formulated to the NRC (1984) recommended protein level but only 95% of the NRC (1984) recommended lysine level. From 9 to 18 wk, both groups were fed diets formulated to the NRC (1984) protein and amino acid specifications.
.35 1.05 1.20 .20
.40 1.00 1.40
.10 .10 2.00
29.3 28.6 2,817 1.65 1.06
6.00
6.00
2,809 1.31 1.07
25.6
2.00
5.00
50.20 34.00
40.00 5.00
44.00
Control
25.7 24.7 2,897 1.53 .93
21 22 2 1
1
25.5 24.6 2,895 1.22 .93
.05
.05 .40 2.00
1
2
.30 .50 .50
.30 .50 .50
2
30
61
8 to 12 w
2.00
8.00
7.50
53.15 28.00
(—1
IO/.\
Age
7.75
. . .
7.50
53.00 28.00
Control
4 to 8 wk PD
2
*PD = protein-deficient diet. The premix contains (in kilograms per 100 kg of diet): ground com, 54.0; amprolium (25%), 2.5; selenium premix (200 m (60%), 6.00; vitamin premix, 25.00; trace mineral premix, 5.00. 3 The vitamin premix contributed the following per kilogram of diet: vitamin A, 8,745 IU; cholecalciferol, 3,745 ICU; vitam 2.91 mg; thiamine HCl, 2.2 mg; riboflavin, 6.6 mg; niacin, 99 mg; pantothenic acid, 15.4 mg; folic acid, 1.2 mg; pyridoxin ethoxyquin, 113.5 mg. 4 The trace mineral premix contributed the following per kilogram of diet zinc oxide (72% Zn), 147 mg; manganous oxid mg; ferrous sulfate monohydrate (31% Fe), 72 mg; and potassium iodide, 1.5 mg.
Ground corn Soybean meal (44% CP) Soybean meal (49% CP) Meat plus bone meal (50% CP) Fishmeal, menhaden Corn gluten meal Wheat middlings Animal-vegetable fat Salt Ground limestone Dicalcium phosphate Defluorinated phosphate DL-methionine L-lysine Premix2A4 Dietary analysis Crude protein Calculated Analyzed ME, kcal/kg Lysine TSAA
Ingredients and analysis
0 to 4 wk PD
TABLE 1. The composition of experimental diets1
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1684
TURNER AND LLBURN control
a
~ontro
Def~c~ent
Defrc~ent
Age lwkl
never caught up with those toms fed the C diet. This confirms the previous report of Ferket and Sell (1989). The results of Ferket and Sell (1989) and those from the present study are not consistent, however, with those of Oju et al. (1988a,b). Oju et al. (1988a,b) reported that protein restriction from 0 to 6 wk did not significantly affect BW in toms and hens after 16 wk (P < .088) and 17 wk (P < .408), respectively. One factor contributing to the discrepancy between experimental results is overall growth rate, which was less in the study gy Oju et al. (1988a,b) compared with thk present results and those of Ferket and Sell (1989). This required less "catching up" by the hens and toms fed the restricted diets. The tibia length and tibia width data support the conclusion of Lilburn and Nestor (1991) that linear (length) and appositional (width) bone development are differentially regulated. Results from that study and a previous report by Nestor et al. (1988) showed that slow- and fast-growing turkeys have similar bone lengths at 16 wk, but defatted bone weight is increased almost 25% in the fastgrowing strain. In the present study, the PD treatment decreased BW and tibia width 25 and 22%, respectively, at 4 wk compared with C toms, whereas tibia length was only decreased 11%. By 14 wk
FIGURE 2. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on tibia length in commercial toms. There were significant age effects on tibia length throughout the experiment. Asterisks indicate that the deficient diet resulted in a significant decrease in tibia length (P 1.05) from 4 to 12 wk.
of age, BW of PD toms was 14% less than that of C toms, whereas tibia width was only 5% less and no difference was observed for tibia length. The lesser effect that protein deficiency had on skeletal development compared with BW would increase relative skeletal support in toms fed the PD diets. This has been suggested by Nestor et al. (1988) as one mechanism by which alterations in skeletal growth might decrease the incidence of leg weakness in heavy toms. These results, together with those of Lilburn and Nestor (1991),
Def8cnent
~onlrol
20 r
,
1
f,
8
li)
12
l4
16
18
Age lwk)
FIGURE 3. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on tibia width in commercial toms. Asterisks indicate that the deficient diet significantly decreased tibia width (P 2 .05) at all ages. There were no age effects after 16 wk.
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FIGURE 1. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on body weight in commercial toms. Asterisks indicate that the deficient diet resulted in a significant decrease in BW (P I.05) at all ages compared with a control diet formulated to National Research Council (1984) protein and amino acid specifications.
Age lwkl
SKELETAL GROWTH IN TURKEY TOMS control
- Control
~ e r ~ ~ , o ? t
.----
Deftctent
I
A g e (wkl
Age (wkl
FIGURE 6. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on epiphyseal bone ash in commercial toms. There were no significant dietary protein effects ( P t .05).
toms fed lower protein diets, as suggested by Stevens and Salmon (1988) and Ferket also suggest that knowledge of the growth and Sell (1989). The Stevens and Salmon and development of the diaphyseal bone (1988) study was based on experimental segment may provide more insight into diets that contained protein levels far in those factors contributing to leg weakness excess of NRC (1984) recommendations. in poultry than information on linear or Extreme caution is always needed when extrapolating the results from this type of whole bone growth. The lack of any significant diet effects study to more practical situations. The on tibia epiphyseal or diaphyseal ash starting diets in the Stevens and Salmon demonstrates that impaired bone minerali- (1988) study also contained a substantial zation is not contributing to the decreased quantity of supplemental dietary fat and incidence of leg weakness observed in the bones were ashed without prior fat extraction. The protein effects on bone ash at 2 wk were minimal (P < .I), so the best
control
Def~c~ent
- Control
-
B
10
12
in
16
..---
LOW Prolean
ie
Age lwki
FIGURE 5. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on femur width in commercial toms. Asterisks indicate that the deficient diet significantly decreased femur width ( P < .05) at all ages. There were no significant age effects after 16 wk.
FIGURE 7. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on diaphyseal bone ash in growing toms. There were no significant dietary protein effects ( P t .05).
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FIGURE 4. The effect of a protein- and lysinedeficient diet from 0 to 8 wk on femur length in commercial toms. Asterisks indicate that the deficient diet reduced femur length ( P < .05) at 8 to 14 wk but there were no significant diet effects on femur length ( P t .05) at 16 and 18 wk of age. There were significant age effects ( P < .05) throughout the study.
1686
TURNER AND LILBURN
conclusion from the report of Stevens and Salmon (1988) is that NRC (1984) recommendations for protein and calcium are adequate for maximal growth and bone ash. REFERENCES
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Aukland, J. N., 1972. Compensatory growth in turkeys: Practical implications and limitations. World's Poult. Sci. J. 28:291-300. Aukland, J. N., and T. R. Morris, 1971. Compensatory growth after undernutrition in market turkeys: Effect of low protein feeding and realimentation on body composition. Br. Poult. Sci. 12:137-150. Bell, R. R., D. T. Engleman, T. L. Sie, and H. H. Draper, 1975. Effect of a high protein intake on calcium metabolism in the rat. J. Nutr. 105: 475-483. Chu, J. Y., M. D. Margen, and F. S. Costa, 1975. Studies in calcium metabolism. II. Effects of low calcium and variable protein intake on human calcium metabolism. Am. J. Clin. Nutr. 28: 1028-1035. El-Maraghi, N.R.H., B. S. Piatt, and R.J.C. Stewart, 1965. The effect of the interaction of dietary protein and calcium on the growth and maintenance of the bones of young, adult, and aged rats. Br. J. Nutr. 19:491-509. Ferket, P. R., and J. L. Sell, 1989. Effect of severity of early protein restriction on large turkey toms. 1. Performance characteristics and leg weakness. Poultry Sci. 68:676-686. Hester, P. Y., I. C. Peng, R. L. Adams, E. J. Furumoto, J. E. Larsen, P. M. Klingensmith, O. A. Pike, and W. J. Stadelman, 1986. Comparison of two lighting regimens and drinker cleaning programmes on the performance and incidence of leg abnormalities in turkey males. Br. Poult. Sci. 27:63-73. 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., F. G. Proudfoot, D. Ramey, and K. B. McRae, 1980. Influence of genotype and diet on general performance of chickens reared to roaster weight. Poultry Sci. 59:748-757. Kerstetter, J. E., and L. H. Allen, 1990. Dietary protein increases urinary calcium. J. Nutr. 120:134-136. Klingensmith, P. M , P. Y. Hester, R. G. Elkin, and C. R. Ward, 1986. Relationship of high intensity step-up lighting to bone ash and growth plate
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