J. Appl. Poult. Res.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J APPL POULT RES 2008. 17:432-439. doi:10.3382/japr.2007-00085
© 2008 Poultry Science Association
This Article
Right arrow Summary Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gunawardana, P.
Right arrow Articles by Bryant, M. M.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Gunawardana, P.
Right arrow Articles by Bryant, M. M.

Research Reports

Effect of Energy and Protein on Performance, Egg Components, Egg Solids, Egg Quality, and Profits in Molted Hy-Line W-36 Hens

P. Gunawardana, D. A. Roland, Sr.1 and M. M. Bryant

Department of Poultry Science, Auburn University, Auburn, AL 36849

1 Corresponding author: roland1{at}auburn.edu


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
An experiment was conducted to determine the influence of dietary energy on performance, egg composition, egg solids, egg quality, and profits of Hy-Line W-36 hens fed different protein levels. The experiment was designed as a 4 x 3 factorial arrangement with 4 added dietary energy levels (0, 79, 158, and 238 kcal of ME/kg) and 3 protein levels (14.89, 16.06, and 17.38%). The basal diets of 17.38, 16.06, and 14.89% protein contained 2,751, 2,784, and 2,815 kcal of ME/kg, respectively. This study lasted 12 wk. Molted Hy-Line W-36 hens (n = 1,440) in phase 1 (70 wk of age) were randomly divided into 12 treatments (8 replicates of 15 hens per treatment). Protein had a significant effect on egg production, egg mass, feed intake, feed conversion, egg weight, percentage of egg shell components, yolk color, and yolk and albumen weight. As dietary energy increased from 0 to 238 kcal of ME/kg by addition of poultry oil, feed intake linearly decreased. Increasing dietary energy also significantly increased BW and egg yolk color. As dietary energy increased, percentage yolk solids increased at the 2 greater dietary protein levels, whereas egg-specific gravity linearly decreased at the 17.38% protein level. Increasing dietary energy and protein significantly improved feed conversion. Increasing protein intake significantly increased albumen and yolk weight but had no influence on yolk, albumen, or whole egg solids. Because feed ingredient and egg prices vary, there can be no fixed ideal dietary energy level for optimal profits during molt phase 1 (70 to 81 wk).

Key Words: protein • dietary energy • hen


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Dietary energy and protein represent approximately 85% of total feed cost. At present, there are wide ranges of dietary energy (2,685 to 3,100 kcal of ME/kg) and protein levels (14.5 to 19%) being used by the egg industry during molt phase 1 [1]. Numerous investigations have focused on methods of influencing egg weight through diet manipulation during various production phases. Increasing levels of protein [2–4], fat [1, 5–7], methionine [5], lysine [8], and linoleic acid [9, 10] have resulted in improvements in egg weight. However, there are inconsistent results on the effect of supplemental fat or dietary energy on egg weight. Some research [11, 12] indicated that addition of supplemental fat increased egg weight. In contrast, other research [13] reported that added fat had no effect on egg weight.

Regulating dietary energy may be the most effective dietary method to manipulate feed intake of laying hens. Earlier studies [1, 6, 14] reported that increasing dietary energy decreased feed intake and improved feed efficiency. Dietary energy level can be easily manipulated with supplemental fat, but some poultry producers do not use fat because of inadequate storing and mixing facilities [11].

Yolk color has a considerable influence on egg marketing. The study of factors affecting the intensity of yolk color is therefore of economic significance for egg producers. The color of yolk depends on the fat soluble carotenoids in dietary fats. Experimental evidence concerning the effect of added fat on yolk color is contradictory. Sullivan and Holleman [15] and Madiedo and Sunde [16] reported that added dietary fat had no effect on egg yolk color; however, Mackay et al. [17] and Stevans et al. [18] reported supplemental fat had a significant effect on egg yolk color.

The liquid egg and breaker egg industry have grown during the last 10 yr. However, there are very few studies in which the effects of the dietary energy and protein on egg composition and egg solids of Hy-Line W-36 hens have been studied. With sharp increases in energy cost, it is important to have a better understanding of how to maximize the use of dietary energy at different protein levels to optimize performance and yield especially for the egg breaker industry. Therefore, the objective of this study was to determine the effect of dietary energy on performance, egg components, egg solids, and profits at different protein levels in Hy-Line W-36 hens during molt phase 1 (from 70 to 81 wk).


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
This study was a 4 x 3 factorial arrangement with 4 added dietary energy levels (0, 79, 158, and 238 kcal of ME/kg) and 3 dietary protein levels (14.89, 16.06, and 17.38%). Ingredients and nutrient composition of experimental diets are shown in Table 1Go. In this experiment, 1,440 Hy-Line W-36 hens [19] just out of molt (70 wk old) were randomly divided into 12 combinations of energy and protein (8 replicates of 15 hens per treatment). Hens were housed 3 per cage in a 40.6 x 45.7 cm cage. Each treatment replicate consisted of 5 adjoining cages. Replicates were equally distributed into upper and lower cage levels to minimize cage level effect. All hens were housed in an environmentally controlled house with temperature maintained as close to 26°C as possible. The house had controlled ventilation and lighting (16L:8D). All hens were supplied with feed and water ad libitum. Animal housing and handling procedures during experimentation were in accordance with guidelines of Auburn University’s Institutional Animal Care and Use Committee. Feed consumption was recorded weekly for calculation of average daily feed consumption. Egg production was recorded daily, and egg weight and specific gravity were recorded once every 2 wk. Egg weight and egg specific gravity were measured using all eggs produced during 2 consecutive days. Egg specific gravity was determined using 9 gradient saline solutions varying in specific gravity from 1.060 to 1.100 in 0.005-unit increments [20]. Mortality was determined daily, and feed consumption was adjusted accordingly. Body weight was obtained by weighing 3 hens per treatment replicate at the end of the experiment. Egg mass (g of egg/hen per day) and feed conversion (g of feed/g of egg) were calculated from egg production, egg weight, and feed consumption.


View this table:
[in this window]
[in a new window]

  		Table 1. Ingredients and nutrient content of the experimental diets
 
Egg components were measured using 3 randomly selected eggs from each replicate at the middle and end of the experiment. Eggs were weighed and broken. The yolks were separated from the albumen. Before yolk weight was determined, the chalaza was removed by forceps. Each yolk was rolled on a blotting paper towel to remove adhering albumen. The shells were cleaned of any adhering albumen and dried for 5 d. Albumen weight was calculated by subtracting the weight of yolk and shell from the whole egg weight.

Three eggs from each treatment replicate were randomly collected at the middle and at the end of the experiment for measuring solids. The yolk and albumen were mixed, and 5 to 6 g of homogenate was pipetted into an aluminum dish with weight recorded to 0.001 g. The sample was dried in an oven for 24 h at 40.5°C [21] and then weighed. Three eggs randomly selected from each treatment replicate were used to analyze the yolk and albumen solids. After yolk was separated from albumen, 3 yolks and albumen per treatment replicate were mixed separately. The procedure for analyzing albumen and yolk solid was the same as the procedure for whole egg solid content. Yolk color and Haugh units were measured (3 eggs from each treatment replicate) at the middle and at the end of the experiment using an egg multitester EMT-5200 [22]. Haugh units were calculated from the records of albumen height and egg weight using the formula: HU = 100 log10 (H – 1.7 W0.37 + 7.56), where HU = Haugh unit, H = height of the albumen (mm), and W = egg weight (g).

Data were analyzed by ANOVA using PROC MIXED of the Statistical Analysis System [23] for a randomized complete block with factorial arrangement of treatments. The factorial arrangement consisted of 4 dietary energy levels and 3 protein levels. Dietary energy and protein were fixed, whereas blocks (location of cages) were random. The following model was used to analyze the data:


Formula

where Yijk = individual observation, µ = overall mean, {alpha}i = dietary energy effect, βj = protein effect, ({alpha}β)ij = interaction between dietary energy and protein, Pk = effect of block, and {varepsilon}ijk = error component. If differences in treatment means were detected by ANOVA, Duncan’s multiple range test was applied to separate means. Contrast statements were utilized to test for linear or quadratic dietary energy effects. A significance level of P ≤ 0.05 was used.


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
There was a significant effect of dietary protein and energy on feed intake (Table 2Go). As added dietary energy increased, feed intake decreased from 96.9 to 94.9 g/hen per day, which resulted in a 2.1% decrease in feed intake. Results of feed intake vs. dietary energy in this study are in agreement with that of Wu et al. [7], Sohail et al. [11], Grobas et al. [1], and Parsons et al. [2]. Increasing dietary protein increased feed intake from 93.2 to 98.8 g/hen per day, resulting in a 6.01% increase of feed intake (Table 2Go). This result was consistent with that of Parsons et al. [2] who reported that increasing CP from 18 to 20% increased feed intake from 104 to 107 g/bird per day and Wu et al. [14] who indicated that, with the increase of dietary protein from 13.99 to 16%, feed intake increased from 102.9 to 105.6 g/hen per day.


View this table:
[in this window]
[in a new window]

  		Table 2. Effect of protein and dietary energy on performance of Hy-Line W-36 hens during molt phase 1 (70 to 81 wk of age)
 
Increasing dietary protein intake from 13.8 to 17.1 g/hen per day increased egg production from 65.2 to 71.7% (Table 2Go). Similarly, Liu et al. [24] and Wu et al. [7] reported that increasing dietary protein improved egg production. Zou et al. [25] reported that increasing dietary protein intake from 15.3 to 16.3 g/hen per day increased egg production by 3.2%. Keshavarz [5] indicated that with an increase of dietary protein intake from 17.4 to 21.4 g/hen per day, egg production increased by 1.9%. However, there was no significant effect of dietary energy on egg production; this result was consistent with that of Harms et al. [6], Wu et al. [7, 14], Parsons et al. [2], Sell et al. [26], and Sohail et al. [11], who reported that egg production was not influenced by supplemental fat.

There was a significant interaction between dietary energy and protein on egg specific gravity (Table 2Go). When added dietary energy increased from 0 to 238 kcal/kg of egg, specific gravity linearly decreased at the 17.38% protein level but not at the other 2 protein levels. This may be related to reduce feed (Ca) intake with increased supplemented fat. There was a significant linear effect of added dietary energy but not dietary protein on BW (Table 2Go). The effect of protein on BW was in agreement with Sohail et al. [11], Grobas et al. [1], and Keshavarz and Nakajima [3], who reported no significant effect of increasing dietary protein levels on BW.

As dietary protein and energy levels increased, feed conversion improved significantly because egg weight and production increased significantly with increased dietary protein and feed intake decreased significantly with increased dietary energy. This result was in agreement with that of Liu et al. [24] and Wu et al. [7, 14], who reported increasing dietary protein and energy improved feed conversion.

Increasing dietary protein intake from 13.8 to 17.1 g/hen per day increased egg mass 5.75 g/hen per day and egg weight by 2.38 g, respectively (Table 2Go). The mechanism by which protein improves egg size is well understood [2, 3, 27, 28]. In this study dietary energy had no influence on egg weight. However, conflicting results arise concerning the influence of supplemental energy on egg weight. De Groote [29], Harms et al. [6], and Wu et al. [14] reported that egg weight increased as dietary energy increased. Leeson [4] also indicated that energy intake had no effect on egg size. Furthermore, Keshavarz [5] reported that young hens respond better to added fat than old hens. The effect of dietary protein on egg weight in this study was consistent with Parsons et al. [2], Keshavarz [5], Leeson [4], Wu et al. [14], and Sohail et al. [11], who reported egg weight of hens fed greater protein was greater than of the hens fed diets containing less protein. The increased egg weight was due to increased albumen and yolk weight (Table 3Go). Shafer et al. [30] also indicated that increasing amino acid (lysine and TSAA) intake had a significant effect on albumen weight.


View this table:
[in this window]
[in a new window]

  		Table 3. Effect of protein and dietary energy on egg components, egg solids, and albumen, yolk, and shell weights of Hy-Line W-36 hens during molt phase 1 (70 to 81 wk of age)
 
Increasing dietary protein significantly decreased percentage egg shell (Table 3Go). This was due to a significant increase of egg weight as protein level increased. As dietary protein increased, albumen and yolk weight significantly increased (Table 3Go). As dietary energy increased, percentage yolk solids significantly increased at the greater dietary protein levels (16.06 and 17.38%) but not at the least (Table 3Go). These results were in agreement with that of Wu et al. [14] and Liu et al. [31]. Furthermore, Prochaska et al. [32] and Novak et al. [33] reported that increasing TSSA and lysine intake per hen daily had a significant influence on albumen weight. These results could be important tools for influencing profits of the breaker, liquid, and powdered egg industries.

Dietary protein and energy had a significant effect on egg yolk color. Increasing dietary energy significantly increased egg yolk color, whereas increasing dietary protein significantly decreased egg yolk color (Table 4Go). These results suggest a strong relationship between added dietary fat, protein, and egg yolk color. Xanthophil is the major colorant responsible for the egg yolk color and is highly fat soluble [34–36]. Because xanthophylls are fat soluble, with the increase of dietary fat, more xanthophylls may be deposited in the egg yolk as pigments. These results agree with those reported by Morihiro et al. [37], Masahiro et al. [38], and Abu Serewa [36]. Increasing dietary protein decreased egg yolk color due to less corn in the diet. This result was in agreement with the results reported by Karunajeewa [39].


View this table:
[in this window]
[in a new window]

  		Table 4. Effect of protein and dietary energy on nutrient intake and egg quality of Hy-Line W-36 hens during molt phase 1 (70 to 81 wk of age)
 
The economic feeding and management program developed by Roland et al. [40, 41] was used to calculate profits at different dietary energy and protein levels at different poultry oil prices. As protein levels increased, profits increased at all dietary energy levels, regardless of poultry oil prices (Table 5Go). Maximum profits were obtained at the greatest dietary protein level (17.38%) and greatest added energy level (258 kcal of ME/kg) with low oil price. With high oil prices, greatest profits were obtained at the least dietary energy and greatest protein level. Because feed ingredient and egg prices vary, there can be no fixed ideal dietary energy level for optimal profits during phase 1 (70 to 81 wk).


View this table:
[in this window]
[in a new window]

  		Table 5. Influence of dietary energy and protein on profits1,2 at different poultry oil prices from 70 to 81 wk of age
 

   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 
  1. Increasing dietary energy by addition of poultry oil had no significant effect on egg production, egg weight, and percentage egg components. However increasing dietary energy had a significant effect on feed intake, egg specific gravity, feed conversion, BW, and yolk color. Increasing dietary energy significantly increased yolk solids at the 2 greater levels of protein but not at the lesser level. This could prove useful to the breaker egg industry.
  2. Increasing dietary protein significantly increased feed consumption, egg production, egg weight, egg mass, and albumen and yolk weight. However, increasing dietary protein significantly decreased egg specific gravity, yolk color, and percentage shell. Feed conversion improved with increased dietary protein.
  3. An ideal dietary energy level for optimal performance could not be determined for laying hens during molt phase 1 (from 70 to 81 wk of age).
  4. There can be no fixed ideal dietary energy level for optimal profits during molt phase 1 because of varying feed ingredient and egg prices.


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. Grobas, S., J. Mendez, C. De. Blas, and G. G. Mateos. 1999. Laying hen productivity as affected by energy, supplemental fat, and linoleic acid concentration of the diet. Poult. Sci. 78:1542–1551.[Abstract/Free Full Text]
  2. Parsons, C. M., K. W. Koelkebeck, Y. Zhang, X. Wang, and R. W. Leeper. 1993. Effect of dietary protein and added fat levels on performance of young laying hens. J. Appl. Poult. Res. 2:214–220.[Abstract/Free Full Text]
  3. Keshavarz, K., and S. Nakajima. 1995. The effect of dietary manipulations of energy, protein, and fat during the growing and laying periods on early egg weight and egg components. Poult. Sci. 74:50–62.[Web of Science][Medline]
  4. Leeson, S. 1989. Energy intake and layer performance. Pages 72–79 in Proc. Calif. Nutr. Conf. Calif. Grain Feed Assoc., Fresno, CA.
  5. Keshavarz, K. 1995. Further investigations on the effect of dietary manipulations of nutrients on early egg weight. Poult. Sci. 74:62–74.[Web of Science][Medline]
  6. Harms, R. H., G. B. Russell, and D. R. Sloan. 2000. Performance of four strains of commercial layers with major changes in dietary energy. J. Appl. Poult. Res. 9:535–541.[Abstract/Free Full Text]
  7. Wu, G., M. M. Bryant, R. A. Voitle, and D. A. Roland Sr. 2005. Effect of dietary energy on performance and egg composition of Bovans White and Dekalb White hens during phase 1. Poult. Sci. 84:1610–1615.[Abstract/Free Full Text]
  8. Zimmerman, R. A. 1997. Management of egg size through precise nutrient delivery. J. Appl. Poult. Res. 6:478–482.[Abstract/Free Full Text]
  9. Jensen, L. S., J. B. Allred, R. E. Fry, and J. McGinnis. 1958. Evidence for an unidentified factor necessary for maximum egg weight in chickens. J. Nutr. 65:219–233.[Abstract/Free Full Text]
  10. Smith, W. K., and J. Pourezza. 1989. Supplemental lipids and sulphur amino acid utilization in laying hens. Br. Poult. Sci. 30:977–978. (Abstr.)
  11. Sohail, S. S., M. M. Bryant, and D. A. Roland Sr. 2003. Influence of dietary fat on economic returns of commercial Leghorns. J. Appl. Poult. Res. 12:356–361.[Abstract/Free Full Text]
  12. Bohnsack, C. R., R. H. Harms, W. D. Merkel, and G. B. Russell. 2002. Performance of commercial layers when fed diets with four levels of corn oil or poultry fat. J. Appl. Poult. Res. 11:68–76.[Abstract/Free Full Text]
  13. Summers, J. D., and S. Leeson. 1993. Influence of diets varying in nutrient density on the development and reproductive performance of White Leghorn pullets. Poult. Sci. 72:1500–1509.[Web of Science]
  14. Wu, G., M. M. Bryant, R. A. Voitle, and D. A. Roland Sr. 2005. Performance comparison and nutritional requirement of five commercial layer strain in phase four. Int. J. Poult. Sci. 4:182–186.
  15. Sullivan, T. W., and K. A. Holleman. 1962. Effect of alfalfa meal and other dietary components on egg yolk color. Poult. Sci. 41:1474–1478.[Web of Science]
  16. Madiedo, G., and M. L. Sunde. 1964. The effect of algae dried Lake Weed, alfalfa and ethoxyquin on yolk color. Poult. Sci. 43:1056–1060.[Web of Science]
  17. Mackay, E., G. J. Mountney, and E. C. Naber. 1963. Yolk color resulting from different levels of paprika extract in the ration. Poult. Sci. 42:32–36.[Web of Science]
  18. Stevans, J., C. Payne, and D. Lewis. 1964. Transmission of pigment from the diet to the egg. Anim. Prod. 6:257–262.
  19. Hy-Line International, West Des Moines, IA.
  20. Holder, D. P., and M. V. Bradford. 1979. Relationship of specific gravity of chicken eggs to number of cracked eggs and percent shell. Poult. Sci. 58:250–251.[Web of Science]
  21. AOAC. 1990. Official Methods of Analysis. 15th ed. Assoc. Anal. Chem., Washington, DC.
  22. Egg multi-tester EMT-5200, Robotmation Co. Ltd., Tokyo, Japan.
  23. SAS institute. 2000. SAS/STAT User’s Guide. SAS Institute Inc., Cary, NC.
  24. Liu, Z., G. Wu, M. M. Bryant, and D. A. Roland Sr. 2005. Influence of added synthetic lysine in low-protein diets with the methionine plus cystine to lysine ratio maintained at 0.75. J. Appl. Poult. Res. 14:174–182.[Abstract/Free Full Text]
  25. Zou, S. G., and Y. Z. Wu. 2005. Effect of supplemental fat on performance of laying hens. Int. J. Poult. Sci. 4:998–1000.
  26. Sell, J. L., R. Angel, and F. Escribano. 1987. Influence of supplemental fat on weight of eggs and yolks during early egg production. Poult. Sci. 66:1807–1812.[Web of Science][Medline]
  27. Scheideler, S. E., and G. W. Froning. 1996. The combined influence of dietary flaxseed variety, level, form, and storage condition on egg production and composition among vitamin E-supplemented hens. Poult. Sci. 75:1221–1226.[Web of Science][Medline]
  28. Scheideler, S. E., D. Jaroni, and G. W. Froning. 1998. Strain and age effects on egg composition from hens fed diets rich in n-3 fatty acids. Poult. Sci. 77:192–196.[Abstract/Free Full Text]
  29. De Groote, G. 1972. A marginal income and cost analysis of the effect of nutrient density on the performance of white Leghorn hens in battery cages. Br. Poult. Sci. 13:503–520.[CrossRef][Web of Science]
  30. Shafer, D. J., J. B. Carey, J. F. Prochaska, and A. R. Sams. 1998. Dietary methionine intake effects on egg component yield, composition, functionality and texture profile analysis. Poult. Sci. 77:1056–1062.[Abstract/Free Full Text]
  31. Sjollema, B., and W. F. Donath. 1940. The vitamin A, carotene and xanthophyll content of the yolk of hens’ eggs. J. Biol. Chem. 77:736–748.
  32. Palmer, L. S. 1915. Xanthophyl, the principal natural yellow pigment of the egg yolk, body fat and blood serum of hen. The physiological relation of the pigment to the xanthophyll of plants. J. Biol. Chem. 77:261–279.
  33. Abu Serewa, S. 1976. Effects of source and level of fat in the hen’s diet on the deposition of dietary oxycarotenoids in egg yolks. Aust. J. Exp. Agric. 16:204–208.[CrossRef]
  34. Morihiro, K., M. Yamazaki, H. Murakami, and M. Tsuro. 2001. Effect of dietary fat source on β-carotene content in egg yolk and egg yolk color. Jpn. Poult. Sci. 38:160–166.
  35. Masahiro, T., M. Yamazaki, H. Murakami, and S. Ishikawa. 1999. Effect of dietary fat on carotene content in egg yolk and egg yolk color. Jpn. Poult. Sci. 36:329–335.
  36. Karunajeewa, H. 1972. Effect of protein and energy levels on laying performance of strains of different body weights. Aust. J. Exp. Agric. 12:385–391.[CrossRef]
  37. Liu, Z., G. Wu, M. M. Bryant, and D. A. Roland Sr. 2004. Influence of added synthetic lysine for first phase second cycle commercial Leghorns with the methionine+cystine/lysine ratio maintained at 0.75. Int. J. Poult. Sci. 3:220–227.
  38. Prochaska, J. F., J. B. Carey, and D. J. Shafer. 1996. The effect of L-lysine intake on egg component yield and composition in laying hens. Poult. Sci. 75:1268–1277.[Web of Science][Medline]
  39. Novak, C., H. Yakout, and S. Scheideler. 2004. The combined effect of dietary lysine and total sulfur amino acid level on egg production parameters and egg components in Dekalb Delta laying hens. Poult. Sci. 83:977–984.[Abstract/Free Full Text]
  40. Roland, D. A. Sr, M. M. Bryant, J. X. Zhang, D. A. Roland Jr, S. K. Rao, and J. Self. 1998. Econometric feeding and management 1. Maximizing profits in Hy-Line W-36 hens by optimizing total amino acid intake and environmental temperature. J. Appl. Poult. Res. 7:403–411.[Abstract/Free Full Text]
  41. Roland, D. A., Sr., M. M. Bryant, J. X. Zhang, D. A. Roland Jr., and J. Self. 2000. Econometric feeding and management of commercial Leghorns: Optimizing profits using new technology. Pages 463–472 in Egg Nutrition and Biotechnology. J. S. Sim, S. Nakai, and W. Guenter, ed. CAB Int., Wallingford, UK.




This Article
Right arrow Summary Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gunawardana, P.
Right arrow Articles by Bryant, M. M.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Gunawardana, P.
Right arrow Articles by Bryant, M. M.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS