21.loC AND 32.2"C1 REQUIREMENTS PREDICTING AMINO ACID FOR BROILERS DESCRIPTION

Transcription

1 PREDICTING AMINO ACID REQUIREMENTS - FOR BROILERS 21.loC AND 32.2"C1 AT MILAN HRUBY, MELVIN L HAMRE, and CRAIG N. COON2 Depatiment ofanimai Science, University of Minnesota, St. Paul, MN Phone: (612) FAX: (612) Primary Audience: Nutritionists, Researchers, Broiler Producers DESCRIPTION OF PROBLEM The accurate prediction of growth and amino acid requirements depends on the complexity and interactions of variables involved in the rearing of broilers [l]. Recently, mathematical equations, based on the results of a series of experiments involving different factors, have been used to predict growth, feed intake, and nutrient levels in diets. Equations or models serve as practical tools for commercial poultry enterprises to directly improve growth and nutrient requirement predictions and achieve the highest possible frnancial effect. Models for amino acid requirement predictions were first constructed for laying hens [2,3,4]. The Israeli researchers focused on the prediction of amino acid requirements for maintenance and feather and carcass growth of broilers [q. The researchers expressed the requirements in mg of amino acidkalorie of respective caloric intake. The authors also followed their amino acid requirement prediction work with field trials. Broilers had the same weight gain and feed efficiency as predicted by the NRC [6] even though lysine and protein levels in modelling diets were 30% and 20% lower, respectively, for 6- to 8-wk old broilers. Specifically, Hurwitz et al. [7l validated a model for the prediction of amino acid requirements, including changes in amino acid composition of the carcass by using new values 1 Published as Paper Number 22087, Scientific Journal Series, Minnesota Agricultural Experiment Station. 2 To whom correspondence should be addressed

2 396 AMINO ACID REQUIREMENTS from a modern amino acid analysis as well as a new set of values for maintenance requirements. The researchers concluded that the original model undercalculated the lysine requirements. The overall results indicated equal performance with model diets despite their considerably lower protein concentrations. Talpaz et al. [8] described a dynamic linear programming algorithm for the formulation of least-cost rations. They based their computations on a number of coefficients and calculations described earlier by Israeli coworkers. The growth pattern of broilers was, for example, described by using the Gompertz function. Emmans [9] stressed the importance of the non-linear Gompertz function for describing the potential growth. Several other papers from the Edinburgh School of Agriculture also focused on the modelling of growth and nutrition in poultry as well as in other species. Emmans and Oldham [lo] concluded that protein and lipid gain can be predicted if the genotype and rates of gain are described. Moreover, birds will need nutrient resources for growth and maintenance of it. The requirement for energy in a thermally neutral environment will be the sum of the separate requirements for maintenance and for the retention of protein and lipid. The requirement for protein will be the sum of the separate requirements for maintenance and the growth of protein [ll]. Fisher [12] calculated amino acid requirements using methods of the Edinburgh School of Agriculture published by Emmans and Fisher [l3]. The principles of the method are understandable and well described with potential problems arising in a feather growth prediction, amino acid retention coefficient estimation, and prediction of feed intake. In other modelling work, Clark et al. [14] determined the response of broilers to different levels of protein, expressing it for a flock. They used the idea of a classical laying hen Reading model by Fisher et al. [4]. Predicting the amino acid requirements for broilers under different temperature treatments was an objective of several research papers. The conclusions ranged from a recommendation to increase nutrient concentrations under high environmental temperature [15] to observations by Gous [16] that a bird would need in such a case to deaminate excess protein and thus produce additional heat. Then, the increase of nutrient level would not be beneficial since birds would try to reduce intake in order to maintain energy balance. The objectives of this experiment were 1) to predict the mature body protein weight of broilers using the Gompertz growth function, 2) to predict the amino acid requirements (g/mcal TMh) for a broiler at two environmental temperatures, and 3) to determine differences in the amino acid requirements based on sex and temperature treatments. MATERIALS AND METHODS The coefficients of the Gompertz growth function for total plucked and bled carcass protein weight were calculated from values obtained as described in the previous papers [17, 181. The form of the Gompertz function used was: BPW = Aexp(-exp(-k(t-t*))), where BPW stands for body protein weight, A is a maximum response (mature body protein weight), k is a growth constant, t is an age in weeks, and t* is time at point of inflection (highest growth rate). For simplicity only weekly values up to 10 wk of age and thereafter every three weeks up to 19 wk of age from six male and female broilers reared under 21.1"C and 32.2'22, respectively, were considered for calculations. Broilers were reared in twelve wood shaving-littered pens in groups of fifty birds (separated by sex) in two environmentally controlled rooms. Weights of the body fat, water, and ash were fitted by using estimated algorithms to bod protein weight (P {k@: Fat = 1.538*P1.1d Water = 3.259*P0. 3; Ash = 0.239*~.8d. The weight of feathers was fitted by using the equations and proposed adjustments of Fisher [12]. The ideal protein and the effective energy requirements for maintenance were calculated using the equation of Brody [19]. The protein requirements were estimated for maintenance at kg/unit [20], where unit stands for Pm0.73*u (Pm = mature body protein weight and u = maturing coefficient), for growth at 1.33 kg protein/kg protein retained and 0.0 kg for fattening of ideal protein. The coefficient of 1.15 kg protein/kg protein retained was employed for day 1 to day 14 to cope better with improved protein efficiency in the first growth period of the broiler. The effective energy requirements were estimated for maintenance

3 HRUBY et al. Research Report 397 at 1.63 MJ/unit [20], where unit stands for PmoOn*u (Pm = mature body protein weight and u = maturing coefficient), for protein retention as 60.3 MJkg [l3], and 56 MJAtg [u)] for lipid retention. The analyses of muscle and feather protein together with an estimate of amino acid levels for maintenance published by Emmans and Fisher [l3] were employed for amino acid requirement calculations. The grams of amino acids calculated from daily ideal protein requirements of broilers were divided by the TME, [21] of total daily feed intake and the amino acid requirements published as such. Thus, the amino acid requirements are presented here as dynamic or day-by-day requirements. RESULTS AND DISCUSSION The estimated genetic growth variables using coefficients of the Gompertz function were lower for females compared to males and lower for broilers under the high temperature treatment (Table 1). The estimated mature protein weight of male broilers reared at 32.2"C was 24.5% less (819 g) compared to male broilers from the 21.1"C treatment (1085 g). The mature protein weight of female broilers from 32.2"C was 35.9% less (508 g) compared to female broilers from the 21.1"C treatment (792 g). The high environmental temperature also decreased the growth rate constant of broilers. The amount of time when the growth rate of protein was maximum (POI) decreased because of the higher environmental temperature (Table 1). The findings suggest that when the estimation of genetic growth variables is a research ob- PARAMETER Maximum responsea Rate constantb Time at POIc RW MALE jective, the introduced environmental temperature can considerably affect such estimations. The fitted weights of chicken body components and feathers by age were obtained using data from the Gompertz function for protein growth, the published algorithms for lipid, ash, and water growth, and the equations and adjustments by Fisher [12] to describe the feather growth (Figure 1). A lipid:protein ratio at maturity (LPm) was estimated to be This lipidprotein ratio is the most likely to be influenced by exogenous factors such as temperature and diet. Emmans [20] stated that this ratio depends on whether a "balanced feed is used. In the current experiment, the free-choice feeding was used based on the hypothesis that a bud is able to choose a "balanced diet" when two diets markedly different in protein level are offered. The lipidprotein ratio estimated for male broilers reared under 21.1"C in the current research is higher than that of the ratio estimated by Fisher [12]. The different strains, feeds, and other factors introduced in both experiments may have produced the different lipid:proteinratio. The estimated coefficients for computation of water and ash in the body from body protein growth agree with Fisher's work and also with findings of Gous [22]. Lower effective energy requirements were observed for broilers at the 32.2"C treatment compared to a 21.1"C treatment (Figure 2). The lower energy requirement for broilers under the high temperature treatment was likely due to a lower growth rate compared to broilers from the 21.1"C treatment. Similar results can TEMPERATURE FEMALE 21.1OC 32.2OC 21.1OC 32.2OC 1085kT2 819k k72 508k ~ k k m-r k k k k

4 ~ 398 AMINO ACID REQUIREMENTS Bled c~c~-fitted *Fat +protein *Feathers +Ash +Water,/' 0 FIGURE 1. FWed body composition of male broilers. The quantity of mature weight components related to mature protein weight are: Pm kg; Fm Pm0."; Ashm Pm; Waterm Pm (Pm = protein at maturity, LPm = 1ipid:protein ratio at maturity, Fm = feather weight at maturity, Ashm = ash weight at maturity, Waterm = water weight at maturity). be observed for ideal protein requirements (Figure 3). Again the broilers under the higher temperature treatment had a lower protein requirement compared to the broilers from thermoneutral temperature treatment. T ie for reaching the highest effective energy requirements (kcavbid/day) on the curve was at 9 wk of age for female broilers at 32.2"C and at 10 wk of age for alj the other treatments (Figure 2). The ideal protein requirements (g/bud/day) were highest at 9 and 8 wk of age for broilers reared at 21.1"C and 32.2"C, respectively (Figure 3). The high environmental temperature of 32.2"C shortens the time for reaching maximum levels for protein requirements which are lower compared to requirements from broilers under the thermoneutral temperature of 21.1"C. Only lysine, TSM, tryptophan, and threonine requirements were chosen for graphical description and comparison with NRC [23]. Table 2 presents all the estimated amino acid requirement values on a weekly basis for male broilers reared under 21.1"C. Predicted amino acid requirements (glmcal) were similar for lysine, TSAA, tryptophan, and threonine compared to NRC [23] (Figure 4). In a previously published paper by Hruby et al. [24], the TME, values were changed into AMEn and c 700~ s E 200 &i. +Male2 tmale32.2c 4 Female32.2C AGE (wk) FIGURE 2. The effective energy requirement for broilers amino acid requirements reported as ratio of amino acid intake (g/day):amen intake. The dynamic amino acid requirement predictions could possibly be more beneficial than step-by-step predictions of amino acid requirements published by NRC. By adjusting the levels of amino acids in diets on day-by-day basis, broiler producers can achieve an economical effect due to a decrease in overfeeding of amino acids. f WMale32.2C I/ 4Female32.2C % FIGURE 3. The ideal protein required for broilers

5 Research Report HRUBYetal. 399 TABLE 2. The prediction of digestible amino acid requirements for male broilers (g/mcal TMEn) - 5 m t LYS FIGURE 4. Comparison of digestible amino acid requirements for broilers Furthermore, there can be an ecological benefit due to optimizing nitrogen output in excreta and thus decreasing a chance of nitrogen pollution. A very high requirement was predicted with the model for broilers from 1 day to 2 wk of age compared to NRC values. Due to yolk utilization during the first week of chick rearing, the amino acid and energy needs can be difficult to calculate. Additionally, the higher room heat during first days can decrease the requirements for energy intake as well [5]. The predicted amiuo acid requirements for female broilers were lower for the observed amino acids (except threonine) compared to requirements for male broilers (Figure 5). High temperature did not significantly change requirements of d o acids for broilers based on g amino

6 400 JAPR AMINO ACID REQUIREMENTS acid/mcal of energy in a diet (Figure 6). Research reports have indicated that the amino acid requirements should increase with increasing environmental temperature [l5, w] because of an expected lower feed intake. Sinurat and Balnave [26], however, reported broilers fed a diet with lower amino acidme ratio showed an improved performance at higher environmental temperatures. The results from the current study also do not support increasing protein and amino acids levels in the diets to compensate for lower feed intake for broilers at high environmental temperatures. 5 1% +Lysine -F $TSAA-F WTHR-F ttry-f +LYS-M +TSAA-M AGE ( Wk) FIGURE 5. The comparison of digestible amino acid requirements for female (F) and male (M) broilers 3. Hurwib, s. and s. Bornstein, 19n. The protein and amino acid requirements of laying hens: Suggested models for calculation. Poultry Si Fisher, C., T.R Morris, and RC. Jennings, A model for the description and prediction of the response #Lysine 32 2C +TSAA 32.2C hthr-32.2c *TRY LYS-21.1C 4TSAA C XTHR C 0,I 0 5. HUIUI(Z, S., D. Sklan, and I. Bartov, New formal ap roaches to the determination of ene amino acicfrequirements of chickens. Poultry Sci. vg! National Research Council, Nutrient Reuirements of Poultry. 6th Rev. Edition. Natl. Acad. Sci., %ashington, DC. 7. H d t q S., I. Plavnik, I. Bartov, and S. Bornstein, 1980.Theaminoacid requirements ofchicks: Experimen T % E Y 0.5 ' FIGURE 6. Comparison of digestible amino acid requirements for male broilers reared at 32.2% or 21.1% CONCLUSIONS AND APPLICATIONS 1. Predicted amino acid requirements in g/mcal TMEn were similar for lysine, TSAA, tryptophan, and threonine when compared to NRC recommendations. 2. Modelling techniques for the prediction of amino acid requirements allow daily requirement prediction, compared to step-by-step prediction by periods as published by NRC. 3. Amino acid requirements (g/mcal) for female broilers were si&icantly lower than those for male broilers. Separate rearing by sex with different diets offered to each group would be an acceptable method for dealing with amino acid requirements by sex. 4. There were no significant differences in predicted amino acid requirements (g/mcal) for broilers reared under 32.2"C compared to broilers reared at 21.1"C. REFERENCES AND NOTES 1. Black, J.L, The evolution of animal growth of layin hens to amino acid intake. Br. Poultry Sci. models. Paees 1-7 in: Proc. of Intl. Modelline Seminar. I 14:46d34. I Wageningez, The Netherlands. 2. Bverlv. T.C Feed and Other Costs of Producing Markei Eggs: Bull. A-1, Maryland Agric. Ekp. Sta., Beltsville, MD.

7 Research Report HRUBYetaI. 401 tal validation of model-calculated requirements. Poultry Sci Talpnz, H., J.R De La Tom, P.J.H. Sharpe, and S. Hluwi(z, Dynamic optimization model for feeding of broilers. Agric. Systems 20: Emmans, G.C., A model of the gmwth and feed intake of &-fed animals, particularlypoultry. Pages in: Com uters in Animal Production. Occasional Pub. No.!, Br. SOC. of Anim. Prod., Edinburgh, Scotland. 10. Emmans, C.C. and J.D. Oldham, Modelling h and nutrition in different species. Pa es ell el ling of Livestock Production Systems. 8. Komer and J.A.M. van Arendonk, eds. Dordrecht, The Netherlands. 11. Emmans, G.C., Problems in modelling the growth of poultry. Pages 1-21 in: Proc. Georgia Nutr. Conf., Atlanta, GA. 12. Fisher, C.,1987. Formal methods of calculating amino acid requirements of growingpoultry. Proc. Avian Forum, Fayetteville, AK. 13. E~m~ma~iss, G.C. and C. Fisher, Problems in nutritional theory. Pa es 9-38 in: Nutritional Re uirements and Nutritionahheory. C. Fisher and K. N.'8oorman, eds. Buttenvorths, London, England. 14. Clark, FA, RM. Goq and T.R Morris, Response of broiler chickens to well-balance protein mixture. Br. Poultly Sci %. 15. Combs, G.F., Feed ingredient composition and amino acid standards for broilers. Pa in: Proc. Maryland Nutr. Conf., College Park, E. 16. Gous, RM., The response of broilers, laying hens and broiler breeders to dietary amino acids. Pages 1-32 in: Pm. 25th Georgia Nutr. Conf., Atlanta, GA. 17. Hruby, M., M.L Hamre, nod C.N. Coon, Free-Choice Feeding and Three Temperature Treatments. J. Appl. Poultry Res Hruby, M., M.L Hamre, and C.N. Coon, Non-linear and linear functions in body protein growth. Submitted to J. Appl. PoultIy Res. 19. Brody, S., Bioenergetics and Growth. Reinhold, New York, NY. 20. Emmens, C.C., Growth, body composition and feed intake. Pages in: Proc. 28th Br. Poultry Breeders Round Table, Edinburgh, Scotland. 21. The metabolizable ene of diets was calculated using the method of Sibbald for Th4b calculation with 40-hr fast prior to intubation. 22. Gous, RM., Future research goals in broiler nutrition identified means of computer simulation modelling. Pa 1-3 in: Proc. Arkansas Nutr. Conf., Little Rock, A!? 23. National Research Councll, Nutrient Reuirements of Poult 9th Rev. Edition. Natl. Acad. %ress,washington, DF: 24. Hruby, M, M.L Hamre, and C.N. Coon, Growth modelling as a tool for redicting amino acid requirements of broilers. J. Appl. {out try Res Thomas, O.P., M. Fmn, and C.B. Tamplin, Broiler nutrition update. Pages in: Proc. Magand Nutr. Conf., College Park, MD. 26. Sinoral, A.P. and D. Balnave, Free-choice feeding of broilers at high temperatures. Br. Poultry Sci Sibbald, M.O., The T.M.E. system of feed evaluation: Methodology, feed composition data, and bibliopphy. Tech. Bull E, Animal Research Contribution Anim. Res. Ctr., Agriculture Canada, Ottawa, ON, Canada. ACKNOWLEDGEMENT This work was supported in part by Gold'n Plump Poultry, Inc., St. Cloud, MN.