Effect of different lysine levels on Arian broiler performances

Abstract

An experiment was conducted to evaluate the performance and carcass yield of Arian male broilers fed diets (starter and grower) with different levels of lysine requirements, high lysine (120% National Research Council, NRC), medium lysine (110% NRC), standard (100% NRC) and low lysine (90% NRC) in a completely randomized experimental design. All diets were isocaloric and isonitrogenous. In broilers receiving 120% of NRC Lysine, body weight in 42 d significantly increased by 248 g compared with standard lysine diet. Feeding broilers with high lysine diets (120% NRC) significantly increased feed intake and body weight gain (22–42 and 0–42 day of age) compared with standard group (P<0.05). Body weight was significantly difference in all of weeks of trail (P<0.05). Lysine levels had no effect on feed conversion ratio. This study showed that increasing lysine level (120% NRC) in diet significantly increased abdominal fat pad, gizzard and heart weight compared with standard group (P<0.05).The results of this study suggest that additional lysine at the level of 120% of NRC in starter and grower diets optimized body weight gain in Arian broiler, whereas reductions in lysine level reduced growth and live weight.

Key Words:

• Lysine
• Body weight
• Breast
• Carcass
• Arian Broiler.

Introduction

Lysine (Lys) is one of the most limiting amino acids in practical corn-soybean meal and sorghum-soybean meal diets for broilers. The level of dietary Lys needed in the grower and finisher period to optimize breast meat yield may be higher than that needed for optimal live performance traits (Kidd et al., 1997; Moran and Bilgili, 1990). Different recommended levels of dietary lysine have been determined across laboratories because numerous variations have existed among experiments (genetic strain, environmental temperature, feed ingredients, protein source and quality, and sex (Han and Baker, 1991; 1993; 1994). It has been shown that current NRC (1994) recommendations for lysine up to d 21 are too low for today’s commercial broiler (Vasquez and Pesti, 1997; Kidd and Fancher, 2001). The NRC dietary total lysine recommendation for starting broiler chicks from 0 to 21 days of age was 1.2% of the diet in the 1984 edition. In the 1994 edition the NRC lowered this recommendation to 1.1% of the diet. Genetic selection by primary breeding companies has resulted in vastly improved growth rate, feed conversion, and breast meat yield of broiler chickens compared with broilers of the previous decade (Havenstein et al., 2003a,^b; Dozier et al., 2008a,^b). As a result, modern broilers require higher dietary amino acid concentrations to optimize performance and breast meat yield compared with the broilers of past years (Kidd et al., 2004; Dozier et al., 2008b). Amino acids are critical for muscle development (Tesseraud et al., 1996) and Lysine (Lys) content in breast muscle is relatively higher than other AA (Munks et al., 1945). Dietary Lys inadequacy has been shown to reduce breast meat yield compared with other muscles (Tessseraud et al., 1996). Therefore, defining dietary AA needs for optimum growth and meat yield is of utmost importance. Lysine, one the key AA for protein synthesis and muscle deposition has also been demonstrated to be involved in the synthesis of cytokines, proliferation of lymphocytes and thus in the optimum functioning of immune system in response to infection. An inadequate supply of Lys would reduce antibody response and cell-mediated immunity in chickens (Geraert and Mercier, 2010). It is well known that protein and Lys and its interaction is considered as an important factor which affects performance and carcass quality of growing chicks and so, dietary requirement of protein is actually a requirement for the Lys contained in the protein.

The objective of the nutritionists has long been to optimize growth and tissue accretion by increasing nutrient density such as AA. The question remains about the potential benefits of AA beyond the protein synthesis for muscle developments. Essential amino acid recommendations for broilers by the NRC (1994) are largely based on experimentation conducted several decades ago. Therefore the objective of this study was to evaluate the four different lysine requirement levels, High Lysine (120% NRC), Medium Lysine (110% NRC), Standard (NRC) and Low Lysine (90% NRC) with same protein and energy requirements recommended by NRC (1994) effects on the Arian broiler performance and carcass composition.

Materials and methods

An experiment with Arian male broilers was conducted from 1 to 6 weeks of age. At day 1, 200 male chicks were placed in 20 floor pens (10 chicks per pen and 0.1 m² floor space/chick). Water and feed were also supplied ad libitum. The lighting regimen was continuous, with 24 hours of light daily in first three days and then was standard 23L:1D, until the end of trail.

The basic chemical composition of the feed was determined according to AOAC (2006). A completely randomized experimental design was used. The following treatments were applied.

1. Diet with High Lysine (H Lys) requirement level (120% NRC).

2. Diet with Medium Lysine (M Lys) requirement level (110% NRC).

3. Diet with Standard Lysine (S Lys) requirement level (100% NRC).

4. Diet with Low Lysine (L Lys) requirement level (90% NRC).

Feeds provided were in mash form and were milled with a 3 mm screen to obtain a similar particle size in all diets. Broiler starter diet formulated according to NRC (1994) recommendations to contain 22.5% CP and 3.040 kcal of ME/kg in starter diets and 19.5% CP and 3.170 kcal ME/kg in grower diets. Diets were formulated isoenergetic and isonitrogenic, based on corn and soybean meal (Table 1). Broiler weight gain, feed intake and feed conversion ratio were measured on a pen basis for the end of week. Prior to selection of birds for processing, feed and water were removed for 10 and 4 hr, respectively. At the end of the experimental period (42 days of age), In order to evaluate carcass quality four birds with body weights as close as possible to the average body weight of the experimental unit were slaughtered per repetition (20 birds/treatment). These birds were weighed, and stunned with a knife, bled for 1.5 min by severing the jugular vein, scalded in water for 1.5 min, and defeathered in a rotary picker for 1 min. Eviscerate were removed and discarded while abdominal fat weights were obtained. Carcasses were chilled in an aerated ice bath for 35 min. Carcass data included cold carcass (without head, feet and skin with bone), breast, thigh and liver weight (Hahn and Spindler, 2002). Breast, thigh and carcass yield (skinless with bone) was determined as the carcass weight in relation to body weight, and expressed as percentage of body weight (%).

Table 1 Composition of experimental diets in starter (0–21) and grower (22–42 d) period.

Period		Starter				Grower
Lysine requirement levels	120%	110%	100%	90%	120%	110%	100%	90%
Treatment	1	2	3	4	1	2	3	4
Ingredients, %
Corn, grain	54.01	55.01	55.39	57.32	64.97	65.87	67.60	66.78
Soybean meal 48%	37.00	36.21	36.01	33.94	28.93	28.10	27.01	27.14
Soybean oil	2.80	2.80	2.80	3.00	3.27	3.40	3.00	3.22
Fish meal	2.00	2.00	2.00	2.00	0.00	0.00	0.00	0.00
Oyster shells	1.88	1.88	1.88	1.88	1.50	1.50	1.40	1.80
Dical. phosphorus	1.00	1.00	1.00	1.00	0.23	0.23	0.23	0.20
Common salt	0.20	0.20	0.20	0.20	0.20	0.20	0.20	0.20
Vitamin premix°	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
Mineral premix°	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
DL-Methionine	0.11	0.10	0.10	0.10	0.20	0.10	0.06	0.11
L-Lysine HCl	0.50	0.30	0.12	0.05	0.20	0.10	0.00	0.05
Calculated nutrients contents
Metabolizable energy, Mcal/Kg	3.04	3.04	3.04	3.04	3.17	3.17	3.17	3.17
Protein, %	22.50	22.50	22.50	22.50	18.50	18.50	18.50	18.50
Ether extract, %	5.12	5.17	5.16	4.93	5.62	5.61	5.60	5.61
Linoleic acid, %	2.58	2.74	2.63	2.54	3.21	3.10	3.20	3.22
Calcium, %	4.62	4.45	4.43	4.52	4.34	4.39	4.39	4.30
Available phosphorus, %	0.89	0.96	0.95	0.97	0.86	0.83	0.83	0.84
Sodium, %	0.13	0.13	0.13	0.13	0.12	0.12	0.12	0.12
LYS, %	1.37	1.25	1.14	1.03	1.22	1.13	1.00	0.91
D LYS, %	1.22	1.11	1.01	0.92	1.08	0.97	0.87	0.79
MET, %	0.51	0.51	0.51	0.51	0.42	0.42	0.42	0.42

° Vitamin and mineral premix includes the following per kilogram of diet: vitamin A (vitamin A acetate), 4960 U; vitamin D (cholecalciferol), 1653 U; vitamin E (dl-α tocopherol acetate), 27 U; menadione (menadione sodium bisulfate complex), 0.99 mg; vitamin B12 (cyanocobalamin), 0.015 mg; folic acid, 0.8 mg; d-pantothenic acid (calcium pantothenate), 15 mg; riboflavin, 5.4 mg; niacin (niacinamide), 45 mg; thiamin mononitrate, 2.7 mg; d-biotin, 0.07 mg; pyridoxine hydrochloride, 5.3 mg; manganese (manganousoxide), 90 mg; zinc oxide, 83 mg; iron sulfate monohydrate, 121 mg; copper sulfate pentahydrate, 12 mg; iodine (calcium iodate), 0.5 mg; selenium (sodium selenite), 0.3 mg.

Data were analyzed by completely randomized design (GLM procedure, An ANOVA of SAS Inst., 2004) and where significance occurred, means were compared with the Duncan multiple range tests. Output data were expressed as means with SEM.

Results and discussion

The results of broiler performance in three periods of trail 0–21, 22–42 and 0–42 d are given in Table 2. Different levels of supplemental lysine had significantly effect on body weight gain in starter and grower and from 0 to 42 days of age (P<0.05). There was a significantly higher in body weight in broilers fed H Lys diet in all of weeks (Figure 1). Maximum weight gain occurred at 120% dietary lysine from 0 to 42 d (2183 g). These results indicated that the lysine requirement of Arian male broilers for maximum body weight gain was similar to those of values reported for other strains (Han and Baker, 1991; 1993) and higher than NRC, (1994) recommended. The results of previous experiments by Zaghari et al. (2002; 2007) indicated that the digestible lysine requirements of Arian male broilers to achieve maximum body weight gain in the starter period was 1.075 %, but in this study showed that this requirements were 1.22%. The lysine requirement for maximum performance of broiler chicks, for both sexes from 0 to 3 wk of age, is 1.209% of the diet for maximum body weight gain and 1.32% for feed efficiency (Vazquez and Pesti, 1997).

Table 2 Effects of lysine levels on broiler performance.

Lysine levels	Feed intake 0–21d, g	Feed intake 22–42 d,g	Feed intake 0–42 d,g	Gain 0–21 d	Gain 22–42 d	Gain 0–42 d	FCR 0–21d, g	FCR 22–42d, g	FCR 0–42d, g
120% NRC	1163^a	3263^a	4426^a	558^a	1625^a	2183^a	2.12	2.02	2.03
110% NRC	1031^b	3009^a^b	4040^b	551^a^b	1419^b	1970^b	1.88	2.13	2.06
NRC	1002^b	2871^b	3873^b	545^a^b	1390^b	1934^b	1.86	2.08	2.01
90% NRC	959^b	3003^a^b	3962^b	486^b	1394^b	1880^b	1.97	2.17	2.11
P-value	0.033	0.045	0.022	0.029	0.046	0.031	0.197	0.302	0.383
SEM	34.96	79.19	97.56	18.63	48.66	56.59	0.073	0.043	0.034

FCR, feed conversion rate.

a—c Means followed by different superscript are significantly different (P<0.05).

Figure 1 Effects of lysine levels on mean body weight. Means followed by different letters are significantly different (P<0.05).

Feed intake was significantly different in 2, 3 and 5 weeks, starter, grower and total experiment (Figure 2). Feed intake was significantly highest in broilers fed H Lys diet in starter and grower periods (P<0.05). At the end of experiment (42 day of age) feed intake was still higher for birds that consumed the H Lys diet during the starter and grower phase. In turn, BW was significantly highest in birds that received H Lys starter and grower diets (P<0.05). Body weight and feed intake were highest for birds consuming the H Lys starter diet (P<0.05), but feed conversions were similar when compared to the other lysine levels diets in starter and grower periods (P>0.05) (Figure 3). Furthermore, recent studies have shown an increase in performance when dietary lysine during the starter phase is higher than recommended (NRC, 1994) levels (Kidd et al., 1998; Kidd and Fancher, 2001). Such effects were observed for the Ross × Ross 508 male (Kidd and Fancher, 2001) and the Avian 34 × Avian male (Kidd et al., 1998).

Figure 2 Effects of lysine levels on feed intake. Means followed by different letters are significantly different (P<0.05).

Figure 3 Effects of lysine levels on feed conversion ratio. Means followed by different letters are significantly different (P<0.05).

Improvements in body weight gain, carcass, and breast percentage for birds fed the H Lys starter diet may have occurred in part due to a higher feed intake. H lysine treatment was highest body weight then need more energy than other treatments, resulted more feed intake. Higher feed intake results higher nutrient intake such as other essential AA and energy. If chicks consumed more feed, so more nutrients such as energy, essential amino acids, micro and macro minerals and vitamins would be absorbed.

This study showed that increasing Lys level in diet increased carcass and breast percentage, as shown in other researches (Gorman and Balnave 1995; Han and Baker, 1994; Kidd et al., 1998). Feeding H Lys diet throughout production optimizes breast meat yield (Kidd et al., 1998, Kerr et al., 1999), it may not always be economically justified. Postnatal protein accretion results from an increase in protein synthesis or a decrease in protein degradation. Diets containing low Lys can limit breast meat formation early in development by reducing protein accretion from protein synthesis and RNA content (Tesseraud et al., 1996). The results of carcass characteristics are given in Table 3. Dietary lysine requirements levels significantly influenced carcass and breast percentage (Table 3). Dietary lysine requirement levels had no influence thigh percentage.

Table 3 Effects of lysine levels on carcass characteristics.

Lysine levels	Carcass, %	Breast, %	Thigh, %	Abdominal fat, %	Liver, %	Gizzard, %	Heart, %
120% NRC	65.18^a	21.07^a	23.30	35.38^a	60.40^a	71.90^a	17.10^a
110% NRC	66.49^a	21.46^a	23.16	14.74^b	51.60^a^b	57.30^b	12.30^a^b
NRC	64.60	21.19^a	22.21	22.85^b	54.7^a	57.60^b	13.10^b
90% NRC	60.94^b	18.88^b	21.88	21.60^b	42.60^b	60.70^a^b	9.88^a^b
P-value	0.013	0.029	0.330	0.003	0.047	0.038	0.025
SEM	0.864	0.469	0.514	2.744	3.018	3.268	1.446

a—c Means followed by different superscript are significantly different (P<0.05).

The concentration of dietary Lys can significantly influence carcass and breast yield for two reasons. Breast meat contains a high concentration of Lys (Table 3) and represents a large portion of carcass meat. Breast muscle development is also affected by sex, age, breed and genetics strain (Moran and Bilgili, 1990; Gorman and Balnave, 1995; Han and Baker, 1991). Their studies have also shown that an additional Lys increase breast meat accretion.

Extensive studies with lysine, for example, have shown that maximal feed efficiency (gain/feed ratio) requires a higher dietary level of lysine than maximal body weight gain (Dozier et al., 2008a; Garcia et al., 2006). In this study showed that broiler fed H Lys level (1.37%) had significantly highest weight gain and feed intake (from 0 to 42 d) and no significantly different in feed efficiency (Table 2).

Han and Baker (1994) studied the lysine requirement of both sexes during the period from 3 to 6 wk of age. The requirement of lysine in a diet containing 20% CP for maximum weight gain was 0.99% for males and 0.91% for females; the requirement for optimum feed efficiency for males was 1.03% and for females is 0.99% lysine in the diet, however in current study Lys requirements for male broiler during the period from 3 to 6 wk of age was 1.22% (120% NRC) for maximum weight gain and feed intake. There was a significant increased in abdominal fat weight of H Lys level group. H Lys level resulted in higher abdominal fat deposition (P<0.01). In this study diets were formulated in the same amino acids (Isonitrogenic) and energy requirements (Isoenergetic) but different in lysine requirement levels. Therefore broilers fed H Lys diet intake more lysine than other treatments. This increase in abdominal fat weight is probably related to the imbalance ideal AA in diet (Rosebrough and Steele, 1985).

Low lysine level treatment in carcass percentage was significantly lower than other treatments (Table 3). This study showed the higher efficiency of these diets (M and H) as they allowed a better transformation of AA intake into tissue synthesis and accretion. This is possibly related to a higher AA availability to synthesize muscle. Diets formulated by H Lys level promoted a better conversion of AA into carcass and breast yield. This suggests that the excess of AA intake caused by the diet with H Lys but imbalanced was deposited as fat, It was also verified that the H Lys diet promoted better conversion of AA into carcass and breast percentage and significantly increased weight of liver, heart and gizzard (Table 3).

Genetic differences have been observed in breast meat yield, abdominal fat pad percentage, and other parts yields (Holsheimer and Veerkamp 1992; Smith et al., 1998). Leclercq (1998) stated that the required level of lysine is highest for minimizing abdominal fat pad percentage followed by maximizing breast meat yield and body weight gain. Feeding H Lys and AA dense diets to broilers increases breast meat yield (Dozier et al., 2007; Eits et al., 2003). Dietary AA responses influencing breast meat yield may be additive among AA (Kerr et al., 1999; De Leon, 2006) but other research found no interactions between Lys and Met (Si et al., 2004). Differences in dietary AA density responses among published research (Corzo et al., 2004, 2005; Kidd et al., 2004) may be related to strain sources. The response to dietary AA/CP density (Smith et al., 1998; Sterling et al., 2006) and dietary Lys (Han and Baker, 1991; Pesti et al., 1994) differs among strain sources. Strains exhibiting rapid muscle growth should have balanced high dietary AA needs for muscle accretion. Although in this study treatment No.1 (H Lys) was highest in body weight, feed intake and also abdominal fat, liver, heart and gizzard weights (Table 3). Improvements in gizzard, liver and heart weights for broilers fed the H Lys starter diet may have occurred in part due to a higher feed intake and body weight.

Conclusions

i) Feeding Arian male broilers high lysine density diets (120% NRC) significantly increased abdominal fat, gizzard and heart weight. ii) Feeding Arian broilers concentrations of dietary Lys above NRC recommendations (20%) in starter and grower diets increased body weight gain and feed intake, but no effect on feed conversion ratio. iii) Male Arian broilers fed the low Lysine diet had reduced growth, feed intake, carcass and breast percentage when compared with those fed additional (+10 and +20% NRC) Lysine diets. iv) Feeding male broilers medium lysine density diet (110% NRC) improved carcass percentage by 1.89% more than broilers fed standard lysine level diet.

Acknowledgments:

the authors would like to thank Islamic Azad University, Saveh Branch, for supporting this study.