Threonine Responses in Commercial Broilers at 30 to 42 Days

61997 Applied Poultry Science, Inc

THREONINE RESPONSES IN COMMERCIAL BROILERS AT 30 TO 42 DAYS M. T.KIDD' and B. J. KERR Nutri-Quest, Inc., 1400 Elbridge Payne Road, Chesterjield MO 63017 Phone: (314) 537-4057 FAX: (314) 532-1710

Primary Audience: Nutritionists, Researchers

The threonine requirement of young chicks has been studied extensively [l,2,3,4, 5, 6, 7, 81. This requirement remains subject to debate, however, because variation exists in such aspects of experimental procedures as crude protein, dietary energy, dietary lysine, chick age, and environmental conditions. Moreover, few studies have addressed the threonine requirement for growing broilers beyond 3 wk of age. Urn [3] conducted experiments using a variety of threonine-deficient basal diets (cordsoybean meal vs. cordsoybeadpeanut meal; wheathoybean meal vs. wheat/soy1

To whom correspondence should be addressed

to 42-day-old broilers was estimated to be 0.68% of diet. Penz et af. [9] also evaluated threonine requirements for broilers from 21 to 42 days of age using a threonine-deficient basal diet composed of wheat, corn gluten meal, soybean meal, and meat and bone meal. The threonine requirements for gain and feed conversion were 0.66% and 0.68% of diet, respectively. Thomas et af. [lo] evaluated the 35 to 49 day threonine requirement in a diet containing peanut meal and crystalline amino acids and reported that the threonine requirement did not exceed 0.56% of diet. Kharlakian et aI. [ll]evaluated the threonine requirement

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beadpeanut meal). The threonine requireDESCRIPTION OF PROBLEM ment for feed conversion and growth for 21-

Research Report KIDD and KERR

42 days of age. Treatments consisted of seven graded levels of threonine (0.55 to 0.85% of diet) and a corn and soybean meal control. Aliquots of threonine in 0.05% increments were added using crystalline L-threonine at the expense of washed builder’s sand. All diets contained the coccidiostat salinomycin. During linear programming crystalline amino acids were included so that the threoninedeficient diets provided all other amino acids at 110% or more of NRC-recommendedlevels [13]. Sodium bicarbonate was also used as a buffer so that the electrolyte balances of threonine-deficient diets would not result in acidosis. Broilers were weighed on a pen basis at 30 and 42 days of age. Weight gain, feed consumption, and feed conversion (adjusted for mortality) were measured for the 30 to 42 day period. Mortality was recorded throughout the experiment. Eight broilers per pen were randomly chosen for processing at 42 days of age. Broilers had free access to water prior to transportation to the pilot processing plant, but feed was withdrawn 8 hr prior to transportation. Broilers were weighed and then processed. After processing, hot carcass weight and abdominal fat pad were recorded. Carcasses were chilled on ice at 0°C for 15 hr and then allowed to drip prior to obtaining a chill weight. Fillets, tenders, and thighs (bone in and skin on) were dissected and weighed. Data were analyzed using General Linear Models of SAS [14]. Pen was the experimental unit for all parameters. Repeated t-test was used to separate means (PS.05). Linear and quadratic regression models generated from General Linear Models of SAS [14] were used for graded levels of threonine when significant effects were found.

MATERIALS AND METHODS A threonine-deficient basal diet composed of corn, peanut meal, grain sorghum, and soybean meal and a corn and soybean meal control diet were formulated using linear programming (Table 1). All proteincontributing ingredients were analyzed for amino acids and crude protein prior to formulation to ensure conformity to total amino acid specifications. After formulation, each basal diet was analyzed for all amino acids and crude protein to compare actual and calculated values. One hundred twenty Ross x Ross male broilers were allocated to each of 56 floor pens containing two bell waterers, three tube feeders, and new (built up) pine shavings. Each pen measured 3.66 x 3.05 m. Broilers were reared in a closed-sided house with thermostatically controlled heating and ventilation fans. House temperature for the 30 to 42 day period was 21°C. Broilers consumed feed and water ad libitum and received continuous incandescent lighting. From 18 to 30 days of age all broilers received a common basal diet meeting or exceeding all nutrient requirements established by the NRC (1994); treatment diets were administered from 30 to

RESULTS AND DISCUSSION Experimental diets and the control diet were analyzed for all amino acids and crude protein. Because analyzed amino acid values were in close agreement with calculated values, only calculated amino acid values are shown (Table 1). The experimental basal diet containing 0.55% total dietary threonine was clearly deficient in threonine, as body weight gain and feed:gain responses indicate (Table 2). The threonine-supplemented sorghum, peanut meal, corn, and poultry meal basal diets

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for 35- to 49-day-old broilers by feeding a cor4peanut meal diet. The threonine requirements for gain and feed conversion of males and feed conversion of females were 0.57% and 0.55% of diet, respectively. However, performance of both male and female broilers in the study of Kharlakian et al. [ll] fed the cor4peanut meal basal diets was below that obtained with the cordsoybean meal control diet containing 0.70% dietary threonine. Very recently Webel et al. [121 estimated total threonine requirements for broilers of 0.70% and 0.60% of diet for the 21 to 42 and 42 to 56 day periods, respectively. In addition, these authors stated that the threonine requirement for 21- to 56-day-old chicks should be expressed as 70% of the chicks’ lysine requirement. Threonine requirement studies for broilers conducted beyond 21 days of age suggest that the NRC [13] 21 to 42 and 42 to 56 day requirements of 0.74% and 0.68% of diet, respectively, are too high. The objective of this experiment was to evaluate threonine responses from 30 to 42 days of age on growth, feed conversion, and carcass traits.

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TABLE 1. ComDosition of threoninedeficientand control basal diets fed from 30 to 42 days of age

1.10

1.10

Threonine

0.55

0.76

Glycine + Serine

1.67

1.96

Arginine

1.59

1.36

Valine

0.90

0.95

Tryptophan

0.20

0.211

Isoleucine

0.80

0.80

Calcium

1.01

0.89

Available phosphorus

0.35

0.35

Electrolyte balance (mE!q/kg)D

188

163

%itamin premix rovided per k of diet: vitamin A (source unspecified), 11,894 IU; cholecalciferol (D-activate( animal sterol), 2,3bIU; vitamin (source uns ecified), 7.9 IU; niacin, 27.8 m antothenic acid, 17.2 mg; riboflavin 6.6 mg; thiamine, 1.32 mg; pyidoxine, 1.3! mg; menadione, 0.72 mg; !%c acid, 0.70 mg; biotin, 0.12 mg cyanocobalamin, 0.01 mg; selenium, 0.12 mg.

fi

‘Mineral remix rovided per kg of diet: manganese, 146 mg; zinc, 120 mg; iron, 48 mg; copper, 4.8 mg; iodine 2.9 mg; caiium, 2% mg. DElectrolyte balance = Dietary sodium

+ Potassium - Chloride in mE!q/kg

of diet.

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Lysine

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KIDD and KERR TABLE 2. Gain and feed:gain ratio of 30- to 42-day-old male broilers as affected by graded levels of L-threonine

DIETARY THREONINE 0.55 0.60

0.65

9Ma"

2.03ab

0.70

951ab

2.02ab

0.75

959a

10.80

Control (0.76% Thr)

I

932a" 920' 10

SEM

Probability value

925"

I

0.001

1.99a

I I

1 I I

2.06k 2HibC

I I

2.1Od 0.02 0.001

a-e

Means with no common superscripts in a column differ significantly ( P < .Ol).

yielded performance equal to or better than that obtained with the corn and soybean meal control containing 0.76% dietary threonine. Increasing dietary threonine from 0.60% to 0.65% resulted in a 7% increase in body weight gain (P~.001).Similarly, the feedgain response improved by 10 points as threonine

TABLE 3. Carcass traits of 30- to 42-dayold male broilers as affected by graded levels of L-threonine

BAbdominal fat expressed as a percentage of hot carcass without fat, neck, and giblets. 'Chilled breast meat includes deboned skinless and boneless major and minor breast muscle. DChilled thighs are bone in and skin on. a 4

Means with no common superscripts in a column differ significantly (P < .OS).

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10.85

I I

increased from 0.60% to 0.65% of diet ( P I .001). Threonine levels in excess of 0.65% of diet yielded no statistically significant beneficial effects for the variables weight gain and feed:gain. These results suggest that the NRC [13] 21 to 42 day threonine requirement of 0.74% of diet may be too high. However, we anticipated that gain and feed:gain would be optimized with a lower level of threonine than the NRC [13] requirement because we evaluated our responses in 30- to 42-day-old birds. Using birds 21 to 30 days of age would yield much higher values than those obtained in the current study. Past research suggests that the threonine requirement for feed:gain may be higher than that for gain in growing broilers [9]. However, this experiment suggeststhat the feed:gain requirement of growing broilers does not exceed that of gain, in agreement with recent findings of Webel et al. [12]. Carcass traits as affected by graded levels of threonine are presented in Table 3. Carcass responses of broilers fed the threoninesupplemented sorghum, peanut meal, corn, and poultry meal basal diets were equal to or better than those obtained with the corn and soybean meal control diet containing 0.76% dietary threonine. Live weight at

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366

creasing dietary threonine. However, total breast yield and total grams of breast meat produced increased linearly with threonine with a negative quadratic term. The threonine requirement estimate from calculating 95% of the asymptote for gain and feed:gain was 0.70% of diet. However, the threonine requirement for grams of breast meat and total breast yield was 0.78 and0.76% of diet, respectively, based on 95% of the asymptote. These results suggest that suboptimal levels of dietary threonine in broilers have profound effects on edible meat, in addition to limiting performance criteria. This experiment evaluated performance and carcass responses in male broilers as affected by graded levels of dietary L-threonine. Carcass traits were influenced by dietary threonine; regression equations may be useful in estimating the amount of saleable meat that a given level of dietary threonine will yield. Knowing the optimal level of dietary threonine required to maximize breast meat yield is important because threonine’s degree of dietary limitation may decrease breast yield responses from dietary lysine and/or methionine.

TABLE 4. Regression equations estimated from aliquots of L-threonine from 0.55 to 0.85% of diet in 30-to 42-day-old male broilers

Thighs(g)

I 291.68 + 1 2 . 2 8 0

I

0.44

I

3.6

I

0.001

I

0.058

I

-

*General linear model probability values were not significant (P1.05) for the variables percentage abdominal fat or thigh yield. %=Percentage total dietary threonine; to predict the performance or carcass trait response, insert the total percentage dietary threonine and perform the appropriate mathematical calculations.

‘R2 = Multiple coefficient of determination;CV = Coefficient of variation. DTotal dietary threonine requirement estimates (% of diet) represent 95% of the asymptote.

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42 days in broilers selected for processing (56 broilerdtreatrnent group) corresponds to results from 30 to 42 day weight gain. In general, results obtained from carcass traits are variable. For example, statistically optimal responses from threonine on carcass yield, percentage abdominal fat, and percentage total breast meat yield occurred at 0.65%, 0.60%, and 0.75% dietary threonine, respectively. Total deboned breast meat and deboned thigh meat were optimized by addition of threonine up to 0.70% of diet (PS.001).The amount of threonine required to optimize breast meat yield (0.75% of diet) was higher than that required to optimize other carcass traits, gain, or feedgain. Table 4 summarizes the results of regression analyses of performance and carcass variables as affected by graded levels of L-threonine. Body weight gain increased linearly with threonine with a negative quadratic term. Feed:gain decreased linearlywith threonine with a positive quadratic term. These results suggest that graded levels of dietary threonine increase gain at a decreasing rate and decrease feedgain at a decreasing rate. Carcass yield increased linearly with in-

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KIDD and KERR

CONCLUSIONS AND APPLICATIONS 1. The levels of dietary threonine that optimized gain, feed:gain, and breast meat yield were 0.65,0.65, and 0.75% of diet, respectively. 2. The minimum value for threonine in linear programming may vary depending upon the most economical production function (gain and feed conversion or breast meat yield).

REFERENCES AND NOTES 8. Holsheimer, J.P., P.F.G. Vereijken, and J.B. Schulte, 1994. Response of broiler chicks to threoninesup lemented diets to 4 weeks of age. Br. Poultry Sci. 35:&-562.

2. Thomas, O.P., AI. Zuckerman, M. Farran, and C.B. Tamplin, 1986. U dated amino acid re uirements of broilers. Pages 79-89in: Proc. Maryland dutr. Conf., Baltimore, MD.

9. P e w AM., Jr., G.L Colnago, and LS. Jensen, 1991. Threonine requirement of broiler chickens from 3 to 6 wk of age. Poultry Sci. 7O(Suppl.1):93.

3. Uzu, G., 1986.Threonine Requirement for Broilers. AEC Information Poultry 252. RhBne Poulenc Animal Nutrition, 03600 Commentry, France.

10. Thomas, O.P., T.A. Shellem, M. Sprague, and H.G. Kharlakian, 1995. Amino acid requirements during the withdrawal period. Pages 71-75 in: Proc. Maryland Nutr. Conf., Baltimore, MD.

4. Thomas, O.P., M. Farran, C.B. Tamplin, and AI. Zuckerman, 1987. Broiler Starter Studies: I. The threonine requirements of male and female broiler chicks. 11. The body composition of males fed varying levels of protein and energy. Page 38-42 in: Proc. Maryland Nutr. Conf., Baltimore, MD.

11. Kharlakian, H.K., T.A. Shellem, O.P. Thomas, and C.K. Baer, 1996. Lysine, methionine, and threonine requirements in broilers during the withdrawal period. Pa es 53-63 in: Proc. Maryland. Nutr. Conf., Baltimore, M%.

5. Robbins, K.R, 1987.Threonine requirement of the broiler chick as affected by protein level and source. Poultry Sci. 66:1531-1534.

12. Webel, D.M., S.R Fernandeq C.M. Parsons, and D.H. Baker, 1996. Digestible threonine requirement of broiler chickens during the period three to six and six to eight weeks posthatching. Poultry Sci. 751253-1257.

6. Smith, N.K., Jr. and P.W. Waldroup, 1988.Investigations of threonine requirements of broiler chicks fed diets based on grain sorghum and soybean meal. Poultry Sci. 67108-112.

13. National Research Council, 1994. Nutrient Requirements of Poultry. 9th Rev. Edition. Natl. Acad. Press, Washington, DC.

7. Rangel-Lugo, M., C.-L Su, and RE Auslic, 1994. Threonine requirement and threonine imbalance in broiler chickens. Poultry Sci. 73:670-681.

14. SAS Institute, 1985. SAS/STAT Guide for Personal Computers. Version 6 Edition. SAS Institute, Inc., Cary, NC.

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1. Thomas, O.P., P.V. Twining, Jr., EH. Bossard, J.L Nicholson, and M. Rubin, 1979. Broiler chick studies with threonine and lysine. Pages4448 in: Proc. Maryland Nutr. Conf., Baltimore, MD.