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British Poultry Science Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/cbps20
Optimum threonine requirement of laying hens G. Huyghebaert
a b
& E. A. Butler
a b
a
Rijksstation voor Kleinveeteelt , Governmental Centre of Agricultural Research Gent , B. Van Gansberghelaan 92, Merelbeke, B 9220, Belgium b
Department of Agriculture , University of Reading , Early Gate, Reading, RG6 2AT, England Published online: 08 Nov 2007.
To cite this article: G. Huyghebaert & E. A. Butler (1991) Optimum threonine requirement of laying hens, British Poultry Science, 32:3, 575-582, DOI: 10.1080/00071669108417382 To link to this article: http://dx.doi.org/10.1080/00071669108417382
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions
British Poultry Science (1991) 32: 575-582
OPTIMUM THREONINE REQUIREMENT OF LAYING HENS G. HUYGHEBAERT AND E. A. BUTLER Rijksstation voor Kleinveeteelt, Governmental Centre of Agricultural Research Gent, B. Van Gansberghelaan 92, B 9220 Merelbeke, Belgium and Department of Agriculture, University of Reading, Early Gate, Reading RG6 2AT, England
Downloaded by [Universite Laval] at 07:51 02 October 2014
Received for publication 28th August 1990
Abstract 1. One experiment was conducted with medium weight laying hens to determine their threonine requirement between 28-38 weeks. 2. Two threonine-limiting diets of identical protein quality (summitdilution) were used and, by dilution, ten protein contents were produced supplying 2.7 to 5.4 g total threonine/kg diet. The diet with the lowest protein was also supplemented with synthetic L-threonine. Each diet was fed to 5 groups of 24 laying hens. 3. The daily threonine requirement of the individual laying hens was estimated by direct methods to be 8.7 mg/g egg output plus 43.49 mg/kg body weight for this experiment. Calculated optimum intakes of threonine for various ratios of costs of input to value of output are tabulated. For example, for a flock of medium weight laying hens producing an average of 50 g daily egg mass, the optimum threonine intake (mg/hen d) varied between 700 and 710 for cost ratios (k-values) varying between 0.002 and 0.001. INTRODUCTION
Estimates of the (optimum) threonine requirement for laying hens vary from 390 to 510 mg threonine/bird d (Adkins et al., 1958; ARC, 1975; Hurwitz and Bornstein, 1973; Smith, 1978; NRC, 1985). Much of the variation in estimating the protein and amino acid requirements of laying hens is caused by nutritional, environmental and genetic factors, as well as the variety of methods which are used to derive the "requirement" from a given set of data. These are only very limited experimental data on which to base the dietary threonine requirement for laying hens. The findings of Adkins et al. (1958) suggest that the laying hen requires about 4-2 g/k§ °f threonine in the diet. Threonine requirements have also been calculated indirectly from maintenance needs and egg formation. In this way Johnson and Fisher (1958), Moran et al. (1967), Hurwitz and Bornstein (1973) and Smith (1978) respectively proposed that a 1-8 kg hen, producing 45 g egg mass/d, requires 390, 440, 500 and 509 mg threonine/d. Finally, ARC (1975) and SCA (1983) recommend 400 mg 575
576
G. HUYGHEBAERT AND E. A. BUTLER
threonine/d for a 1-8 kg hen with a daily egg output of 50 g while the NRC (1985) recommends 440 mg threonine/d. This experiment was designed such that, when the concentration of the limiting amino acid (threonine) was varied, the concentrations of the other amino acids varied in proportion. This was accomplished using the dilution technique of Pilbrow and Morris (1974) where, in order to produce a range of diets with increasing concentrations of protein and a near-constant amino acid balance, a carefully formulated low-protein dilution mixture is used to dilute a high protein summit diet.
Downloaded by [Universite Laval] at 07:51 02 October 2014
MATERIALS AND METHODS
The experiment was conducted with a flock of 1320 layers between 28 and 38 weeks of age. The birds, which were medium-weight laying hens (ISA Brown), were housed 4 birds to a cage in a three-tier battery under a normal environment. In the experiment there were 55 groups of 24 laying hens, allowing 5 complete replications of the 11 treatments. The mash diets were fed ad libitum.
The required dietary range of threonine contents was obtained by formulating a "summit" mix calculated to contain 5-4 g threonine/kg and a "dilution" mix calculated to contain 2-7 g threonine/kg. The summit mix was designed to provide threonine (the most limiting amino acid) at 1-23 times and the other amino acids at not less than 1-6 times the assumed requirements (Table 1). The summit mix was also supplemented with non-essential amino acids in order to prevent a lack of non-essential nitrogen. The dilution mix was designed to provide threonine at 0'61 times and the other amino acids at not less than 0-80 times the assumed requirements. The two isoenergetic diets had similar amino acid profiles. Summit and dilution mixes were combined to produce a series of ten diets of differing threonine contents (see Table 3). The diet with the lowest protein content (90 g/kg) was supplemented with 0-8 g synthetic L-threonine per kg in an eleventh treatment to test whether threonine was the most limiting amino acid. This supplement of 0-8 g synthetic L-threonine per kg of diet was just sufficient to bring the dietary threonine to 0-8 of the assumed requirement (see Table 1). The results from this latter treatment were, however, not taken into account when analysing the responses. Both diets (Table 2) were analysed for total and for digestible amino acids using a bioassay described by Huyghebaert et al. (1979). Each mix of diet was analysed for total nitrogen, mainly to check the accuracy of mixing. The experiment consisted of a 6-week period of adaptation (or depletion) and a 4-week main period. During the main period, egg production, egg weight and food intake were recorded. Body weight was estimated at the start and the end of the main period by weighing birds from one-third of the laying flock. The results were analysed according to the Reading model (Pilbrow and Morris, 1974), thereby taking into account the mean performance and the variation of individuals about this mean. Moreover, all the results were statistically subjected to analysis of variance and Duncan's multiple range test (Snedecor and Cochran, 1980).
THREONINE REQUIREMENT OF LAYERS
577
TABLE 1
Calculated amino acid contents (g/kg) of the summit and dilution mixtures
Downloaded by [Universite Laval] at 07:51 02 October 2014
Isoleucine Leucine Lysine Methionine Methionine + cystine Phenylalanine Phenylalanine + tyrosine Threonine Tryptophan Valine Arginine Histidine
Assumed requirement 6-5 8-0 7-5 3-5 6-5 4-5 8-3 4-4 1-5 6-2 6-5 2-0
Summit mixture 10-4* 13-2 12-0* 7-5 10-4* 7-2* 13-3* 5-4** 2-4* 9-9* 10-4* 3-5
Dilution mixture 5-2* 6-4* 6-0* 3-4 5-2* 3-6* 6-7* 2-7** 1-2* 5-0* 5-2* 1-9
* Figures are minimum values specified in the computer matrix. ** Figures are maximum values specified in the computer matrix. R E S U L T S AND D I S C U S S I O N
Table 3 shows the principal average results measured from 6 to 10 weeks after introduction of the experimental diets. Daily egg mass was curvilinearly related to concentration of dietary protein. The response of egg mass to dietary protein concentration can be partitioned between egg number and egg weight. The pattern of response in egg weight to threonine dose was similar to that for rate of egg production. A higher dietary threonine content was (apparently) needed for maximum egg weight (diet 2: 5-1 g/kg) than for maximum egg number (diet 4: 4-5 g/kg). This difference in threonine requirement may, however, be biased by the higher LSD (Table 3) associated with rate of lay than with egg weight. It has been commonly thought that egg weight is a more sensitive response criterion than rate of lay for hens fed on a diet only slightly deficient in an amino acid. However, Morris and Gous (1988) have recently concluded that small increases in protein or amino acid close to the dietary optimum resulted in proportionally equal responses in both rate of lay and egg weight. Moreover, recent investigations by Jensen (1989) have shown that the effect of an amino acid deficiency depends on the particular amino acid. At lower amino acid inputs, it is clear that the rate of lay is more depressed than egg weight. Egg size does not fall below 0-85 of its maximum value until amino acid intake is well below 0*5 of the optimum value, whereas rate of lay is only 0-35 of its potential value when amino acid intake is reduced by 60%. These results confirm the findings of Morris and Gous (1988). Food intake was greatly (more than 35%) affected by dietary protein concentration. This finding contrasts with the results of a previous experiment (Huyghebaert et al., 1990) on the isoleucine requirement, where food intake was only slightly changed. There was some evidence (Table 3) of greater intakes of mildly deficient diets than of adequate diets, probably showing that the hens are attempting to compensate for lower amino acid intakes. This is in agreement with the findings of Morris and Wethli (1978) and Gous et al. (1987).
578
G. HUYGHEBAERT AND E. A. BUTLER TABLE 2
Downloaded by [Universite Laval] at 07:51 02 October 2014
Composition of the summit and dilution mixes Yellow maize Alfalfa (18% crude protein) Oats Tapioca rootmeal Wheat middlings Wheat Maize gluten meal (65%) Soyabean meal (44%) Animal fat Soyabean oil Dicalciumphosphate. H2O Limestone (hen sized/powder = 1/1) Sodium chloride L-isoleucine L-valine L-arginine L-tyrosine L-leucine L-lysine-HCl DL-methionine L-tryptophan L-glutamic acid Carophyl-red (premix) Carophyl-yellow (premix) , Vitamins and minerals* (premix) Chemical composition MEn, MJAg Crude protein, g/kg Lysine, g/kg Methionine 4- cystine Isoleucine, g/kg Threonine, g/kg total digestible (ADC, %)
Summit mix —
3-16 5-00 7-67 13-16 35-00 4-76 10-35 4-00 2-00 1-14 9-40 0-38 0-38 0-23 ' 0-19 0-07 —
0-66 0-43 0-07 1-00 0-002 0-002 1-00 100-054 11-70 166-0 12-0 10-4 10-4 5-4
4-3 (80)
Dilution mix 11-78 —
5-00 20-00 9-82 35-00 0-59 0-72 3-74 0-26 1-27 9-48 0-34 0-19 0-10 0-08 0-04 0-0035 0-37 0-19 0-03 —
0-002 0-002 1-00 100-0075 11-70 90-0 6-0 5-2 5-2
2-7 1-9 (70)
* (premix) supplements (mg/kg of diet: retinol, 405; cholecalciferol, 0-05; thiamine hydrochloride, 1-0; riboflavin, 5-4; D-calcium pantothenate, 13-5; pyridoxine hydrochloride, 1-1; cyanocobalamin, 00135; nicotinic acid, 40-0; I, 2-1; Co, 1-4; Fe, 65-0; Cu, 7-2; Mn, 86-0; Zn, 57-0; Mg, 114-0.
Because daily egg mass was more reduced than food intake, food conversion efficiency was adversely affected by suboptimal dietary protein. A progressive increasing loss in body weight was observed at lower dietary threonine concentrations (below 4 g/kg of diet). There were clear and significant (P
British Poultry Science Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/cbps20
Optimum threonine requirement of laying hens G. Huyghebaert
a b
& E. A. Butler
a b
a
Rijksstation voor Kleinveeteelt , Governmental Centre of Agricultural Research Gent , B. Van Gansberghelaan 92, Merelbeke, B 9220, Belgium b
Department of Agriculture , University of Reading , Early Gate, Reading, RG6 2AT, England Published online: 08 Nov 2007.
To cite this article: G. Huyghebaert & E. A. Butler (1991) Optimum threonine requirement of laying hens, British Poultry Science, 32:3, 575-582, DOI: 10.1080/00071669108417382 To link to this article: http://dx.doi.org/10.1080/00071669108417382
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions
British Poultry Science (1991) 32: 575-582
OPTIMUM THREONINE REQUIREMENT OF LAYING HENS G. HUYGHEBAERT AND E. A. BUTLER Rijksstation voor Kleinveeteelt, Governmental Centre of Agricultural Research Gent, B. Van Gansberghelaan 92, B 9220 Merelbeke, Belgium and Department of Agriculture, University of Reading, Early Gate, Reading RG6 2AT, England
Downloaded by [Universite Laval] at 07:51 02 October 2014
Received for publication 28th August 1990
Abstract 1. One experiment was conducted with medium weight laying hens to determine their threonine requirement between 28-38 weeks. 2. Two threonine-limiting diets of identical protein quality (summitdilution) were used and, by dilution, ten protein contents were produced supplying 2.7 to 5.4 g total threonine/kg diet. The diet with the lowest protein was also supplemented with synthetic L-threonine. Each diet was fed to 5 groups of 24 laying hens. 3. The daily threonine requirement of the individual laying hens was estimated by direct methods to be 8.7 mg/g egg output plus 43.49 mg/kg body weight for this experiment. Calculated optimum intakes of threonine for various ratios of costs of input to value of output are tabulated. For example, for a flock of medium weight laying hens producing an average of 50 g daily egg mass, the optimum threonine intake (mg/hen d) varied between 700 and 710 for cost ratios (k-values) varying between 0.002 and 0.001. INTRODUCTION
Estimates of the (optimum) threonine requirement for laying hens vary from 390 to 510 mg threonine/bird d (Adkins et al., 1958; ARC, 1975; Hurwitz and Bornstein, 1973; Smith, 1978; NRC, 1985). Much of the variation in estimating the protein and amino acid requirements of laying hens is caused by nutritional, environmental and genetic factors, as well as the variety of methods which are used to derive the "requirement" from a given set of data. These are only very limited experimental data on which to base the dietary threonine requirement for laying hens. The findings of Adkins et al. (1958) suggest that the laying hen requires about 4-2 g/k§ °f threonine in the diet. Threonine requirements have also been calculated indirectly from maintenance needs and egg formation. In this way Johnson and Fisher (1958), Moran et al. (1967), Hurwitz and Bornstein (1973) and Smith (1978) respectively proposed that a 1-8 kg hen, producing 45 g egg mass/d, requires 390, 440, 500 and 509 mg threonine/d. Finally, ARC (1975) and SCA (1983) recommend 400 mg 575
576
G. HUYGHEBAERT AND E. A. BUTLER
threonine/d for a 1-8 kg hen with a daily egg output of 50 g while the NRC (1985) recommends 440 mg threonine/d. This experiment was designed such that, when the concentration of the limiting amino acid (threonine) was varied, the concentrations of the other amino acids varied in proportion. This was accomplished using the dilution technique of Pilbrow and Morris (1974) where, in order to produce a range of diets with increasing concentrations of protein and a near-constant amino acid balance, a carefully formulated low-protein dilution mixture is used to dilute a high protein summit diet.
Downloaded by [Universite Laval] at 07:51 02 October 2014
MATERIALS AND METHODS
The experiment was conducted with a flock of 1320 layers between 28 and 38 weeks of age. The birds, which were medium-weight laying hens (ISA Brown), were housed 4 birds to a cage in a three-tier battery under a normal environment. In the experiment there were 55 groups of 24 laying hens, allowing 5 complete replications of the 11 treatments. The mash diets were fed ad libitum.
The required dietary range of threonine contents was obtained by formulating a "summit" mix calculated to contain 5-4 g threonine/kg and a "dilution" mix calculated to contain 2-7 g threonine/kg. The summit mix was designed to provide threonine (the most limiting amino acid) at 1-23 times and the other amino acids at not less than 1-6 times the assumed requirements (Table 1). The summit mix was also supplemented with non-essential amino acids in order to prevent a lack of non-essential nitrogen. The dilution mix was designed to provide threonine at 0'61 times and the other amino acids at not less than 0-80 times the assumed requirements. The two isoenergetic diets had similar amino acid profiles. Summit and dilution mixes were combined to produce a series of ten diets of differing threonine contents (see Table 3). The diet with the lowest protein content (90 g/kg) was supplemented with 0-8 g synthetic L-threonine per kg in an eleventh treatment to test whether threonine was the most limiting amino acid. This supplement of 0-8 g synthetic L-threonine per kg of diet was just sufficient to bring the dietary threonine to 0-8 of the assumed requirement (see Table 1). The results from this latter treatment were, however, not taken into account when analysing the responses. Both diets (Table 2) were analysed for total and for digestible amino acids using a bioassay described by Huyghebaert et al. (1979). Each mix of diet was analysed for total nitrogen, mainly to check the accuracy of mixing. The experiment consisted of a 6-week period of adaptation (or depletion) and a 4-week main period. During the main period, egg production, egg weight and food intake were recorded. Body weight was estimated at the start and the end of the main period by weighing birds from one-third of the laying flock. The results were analysed according to the Reading model (Pilbrow and Morris, 1974), thereby taking into account the mean performance and the variation of individuals about this mean. Moreover, all the results were statistically subjected to analysis of variance and Duncan's multiple range test (Snedecor and Cochran, 1980).
THREONINE REQUIREMENT OF LAYERS
577
TABLE 1
Calculated amino acid contents (g/kg) of the summit and dilution mixtures
Downloaded by [Universite Laval] at 07:51 02 October 2014
Isoleucine Leucine Lysine Methionine Methionine + cystine Phenylalanine Phenylalanine + tyrosine Threonine Tryptophan Valine Arginine Histidine
Assumed requirement 6-5 8-0 7-5 3-5 6-5 4-5 8-3 4-4 1-5 6-2 6-5 2-0
Summit mixture 10-4* 13-2 12-0* 7-5 10-4* 7-2* 13-3* 5-4** 2-4* 9-9* 10-4* 3-5
Dilution mixture 5-2* 6-4* 6-0* 3-4 5-2* 3-6* 6-7* 2-7** 1-2* 5-0* 5-2* 1-9
* Figures are minimum values specified in the computer matrix. ** Figures are maximum values specified in the computer matrix. R E S U L T S AND D I S C U S S I O N
Table 3 shows the principal average results measured from 6 to 10 weeks after introduction of the experimental diets. Daily egg mass was curvilinearly related to concentration of dietary protein. The response of egg mass to dietary protein concentration can be partitioned between egg number and egg weight. The pattern of response in egg weight to threonine dose was similar to that for rate of egg production. A higher dietary threonine content was (apparently) needed for maximum egg weight (diet 2: 5-1 g/kg) than for maximum egg number (diet 4: 4-5 g/kg). This difference in threonine requirement may, however, be biased by the higher LSD (Table 3) associated with rate of lay than with egg weight. It has been commonly thought that egg weight is a more sensitive response criterion than rate of lay for hens fed on a diet only slightly deficient in an amino acid. However, Morris and Gous (1988) have recently concluded that small increases in protein or amino acid close to the dietary optimum resulted in proportionally equal responses in both rate of lay and egg weight. Moreover, recent investigations by Jensen (1989) have shown that the effect of an amino acid deficiency depends on the particular amino acid. At lower amino acid inputs, it is clear that the rate of lay is more depressed than egg weight. Egg size does not fall below 0-85 of its maximum value until amino acid intake is well below 0*5 of the optimum value, whereas rate of lay is only 0-35 of its potential value when amino acid intake is reduced by 60%. These results confirm the findings of Morris and Gous (1988). Food intake was greatly (more than 35%) affected by dietary protein concentration. This finding contrasts with the results of a previous experiment (Huyghebaert et al., 1990) on the isoleucine requirement, where food intake was only slightly changed. There was some evidence (Table 3) of greater intakes of mildly deficient diets than of adequate diets, probably showing that the hens are attempting to compensate for lower amino acid intakes. This is in agreement with the findings of Morris and Wethli (1978) and Gous et al. (1987).
578
G. HUYGHEBAERT AND E. A. BUTLER TABLE 2
Downloaded by [Universite Laval] at 07:51 02 October 2014
Composition of the summit and dilution mixes Yellow maize Alfalfa (18% crude protein) Oats Tapioca rootmeal Wheat middlings Wheat Maize gluten meal (65%) Soyabean meal (44%) Animal fat Soyabean oil Dicalciumphosphate. H2O Limestone (hen sized/powder = 1/1) Sodium chloride L-isoleucine L-valine L-arginine L-tyrosine L-leucine L-lysine-HCl DL-methionine L-tryptophan L-glutamic acid Carophyl-red (premix) Carophyl-yellow (premix) , Vitamins and minerals* (premix) Chemical composition MEn, MJAg Crude protein, g/kg Lysine, g/kg Methionine 4- cystine Isoleucine, g/kg Threonine, g/kg total digestible (ADC, %)
Summit mix —
3-16 5-00 7-67 13-16 35-00 4-76 10-35 4-00 2-00 1-14 9-40 0-38 0-38 0-23 ' 0-19 0-07 —
0-66 0-43 0-07 1-00 0-002 0-002 1-00 100-054 11-70 166-0 12-0 10-4 10-4 5-4
4-3 (80)
Dilution mix 11-78 —
5-00 20-00 9-82 35-00 0-59 0-72 3-74 0-26 1-27 9-48 0-34 0-19 0-10 0-08 0-04 0-0035 0-37 0-19 0-03 —
0-002 0-002 1-00 100-0075 11-70 90-0 6-0 5-2 5-2
2-7 1-9 (70)
* (premix) supplements (mg/kg of diet: retinol, 405; cholecalciferol, 0-05; thiamine hydrochloride, 1-0; riboflavin, 5-4; D-calcium pantothenate, 13-5; pyridoxine hydrochloride, 1-1; cyanocobalamin, 00135; nicotinic acid, 40-0; I, 2-1; Co, 1-4; Fe, 65-0; Cu, 7-2; Mn, 86-0; Zn, 57-0; Mg, 114-0.
Because daily egg mass was more reduced than food intake, food conversion efficiency was adversely affected by suboptimal dietary protein. A progressive increasing loss in body weight was observed at lower dietary threonine concentrations (below 4 g/kg of diet). There were clear and significant (P
