Comparative performance of commercial broilers fed Herbomethione® as a replacement for DL-methionine in diet

Abstract

To compare the effects of Herbomethione® and DL-methionine on growth, carcass characteristics, biochemical parameters and antibody profile, a total of 144, day-old (Vencobb) broiler chicks were equally and randomly assigned to three diets for 6 weeks. The diets included Corn–Soyabean meal-based control diet supplemented either with synthetic methionine (DL-M) or two herbal sources of methionine: HM-6 and HM-7. The birds were divided into three dietary treatments of 48 birds each and each treatment group was replicated three times with 16 birds per replicate. Both the herbal methionine supplements were procured from Indian Herbs Research and Supply Co. Ltd, Saharnpur, India. DL-M significantly produced a higher growth rate than HM-6 and HM-7 treated groups and had a slightly better efficiency of feed, protein and energy utilization. The source of methionine did not influence the carcass yield and organoleptic properties of the meat. HM-7 resulted in a higher antibody titre against NDV with a higher level of total protein and circulatory immune complex in the sera. The lipid content in the liver was higher in both HM-6 and HM-7 groups than DL-M. HM-6 and HM-7 were, respectively, 91.9 and 92.3% bio-efficient for growth relative to DL-M (100%). Under the conditions of this study, it was concluded that Herbomethione® (both HM-6 and HM-7) was not an effective alternate for DL-methionine to sustain a fast growth rate in commercial broiler chicks.

Keywords:

• broiler
• methionine
• Herbomethione®
• growth
• bio-efficacy

Introduction

Methionine is an essential amino acid needed for healthy and productive poultry. It is considered to be the first limiting amino acid in corn–soyabean-based poultry diet, followed by lysine and arginine (Baker 1989; NRC 1994; Cheeke 1999). Its shortage in poultry diet constrains the bird's growth, reduces feed efficiency and in extreme cases causes nutritional deficiency. Methionine supplementation can alter the immune response and is beneficial in reducing the immunologic stress (Tsiagbe et al. 1987a; Klasing & Barnes 1988). Methionine is metabolically linked with cystine and choline and is necessary for producing keratins used in feather growth. Reduced feathering has been reportedly linked to the lack of methionine and cystine (NRC 1994). The bovine spongiform encephalomyelitis and salmonella infection crisis in European countries, have led to the demand for poultry fed exclusively on vegetable diets, which, unfortunately, are methionine deficient. In this scenario, the formulation of diets needs attention to the issues such as the availability and source of methionine.

DL-methionine supplementation in poultry feeds is a common practice in cereal and vegetable protein-based diets, but its synthesis involves the use of highly toxic and hazardous chemicals such as hydrogen cyanide, ammonia and mercaptaldehyde (NOSB 2001). Baker (1991) reported that DL-methionine is metabolized to highly toxic methylthio-propionate when fed to birds and results in reduced feed intake, lower growth rate and depressed feed conversion.

Synthetic methionine will be considered among the prohibited substances in organic farming after October 2008 (Anonymous 1999; NOSB 2001).

The use of natural and organic protein sources in animal feeding is therefore stressed. But organic feedstuffs cannot meet the bird's requirements particularly to sustain high growth rate in broiler until the methionine level is raised through dietary supplementation. So keeping these problems in view, the effectiveness of Herbomethione® claimed to be the herbal source of methionine by the suppliers M/s Indian Herbs Res. and Supply Co. Ltd, Saharanpur, U.P., and was tested as an alternate for synthetic DL-methionine in broiler chicks.

Materials and methods

Chicks, treatments and management

Vaccinated 1-d-old sexed commercial (Vencobb) broiler chicks (n=144) were randomly allocated to nine groups with 16 nos. each and equal sex ratio and placed in individual floor pens. The chicks were protected against New Castle and Infectious Bursal Diseases by routine vaccination. The corn–soyabean meal-based diets (BIS 1992) supplemented with DL-methionine (DL-M), Herbomethione® (HM-6 and HM-7), were randomly offered to three groups each thus forming triplicate groups for each treatment. The chicks were fed a starter diet (2800 kcal ME /kg, 22% CP) for first 3 weeks, and the broiler finisher diet (2927 kcal ME /kg, 20.07% CP) for the following 3 weeks (Table 1). Feed and fresh water were made available ad libitum all the times. The feeds were analysed for crude protein content as per AOAC International (2000) methods.

Table 1. Composition of starter and finisher basal diets (g/kg).

Ingredient	Starter diet	Finisher diet
Maize	520	582
Soyabean meal	395	335
Rice polish	50
Dicalcium phosphate	20	16
Lime stone powder	10	12
Salt	5	5
DL-methionine^a (T0)	1.3	1.1
Additives^b	+	+
Composition
CP (%)	22.00	20.07
ME(Kcal/kg)	2800	2927

^a DL-M of basal ration (T₀) was replaced by HM-6 and HM-7 in T₁ and T₂ treatment diets, respectively. All other ingredients were the same.

^b Provided per kg diet: Vitamin A, 6000IU;Vitamin B₂, 6mg; Vitamin D₃, 600IU;Vitamin K, 1 mg; Vitamin B₁₂, 0.015mg; Thiamine, 5mg; Riboflavin, 6mg; Pantothenic acid, 15mg; Nicotinic acid, 40mg; Biotin, 0.2mg; Folic acid, 1.0mg; Ferrous sulphate, 120mg; Cupric sulphate, 12 mg; Potassium iodide, 1mg; Manganous sulphate, 90mg; Zinc sulphate, 60mg; Liver tonic (Superliv™), 250mg; Toxin binder (Ultrasil™), 1000mg; Lincomycin (Unimix™), 250mg; VitaminC, 100mg; Salinomycin, 500mg; Choline Chloride, 1400mg.

Herbomethione®

The Herbomethione® (HM-6 and HM-7) were supplied by M/s Indian Herbs Research and Supply Co. Ltd. Saharnpur, India. It contains methionine in a readily digestible composition in conjugated dipeptide and oligopeptide form and methionine conjugates along with enzymes like methionine synthase etc. required for conversion of methionine to S-adenosyl methionine (SAM) and then protein synthesis. Aspartate, cysteine and serine naturally present in herbal methionine facilitate regular synthesis of methionine as per physiological needs of birds and animals. Herbomethione containing amino acid intermediates and precursors of methionine maintains sustained synthesis, bioavailability and functioning. The basic ingredients in HM-6 and HM-7 are the same with some difference in their proportions and concentrations.

Growth performance

Live weight and feed intake per pen basis were recorded for the calculation of weight gain and feed conversion ratio (feed/gain), energy efficiency ratio (energy intake/gain in live weight), and protein efficiency ratio (gain in live weight/protein intake) during each week period.

Immune response, biochemical evaluation, carcass yield and organoleptic characteristics

At week 4, four birds were randomly selected from each dietary treatment. Blood sample (5–10 ml) collected by cardiac puncture, was allowed to clot at room temperature.

The serum thus collected was used to estimate various biochemical parameters like total protein (Lowry et al. 1951), albumin, circulatory immune complexes (Creighton et al. 1973) and total immunoglobulins (Oser 1965). Antibodies specific for New Castle Disease Virus (NDV) were detected in sera of chicks by means of haemaggultination inhibition (HI) test (OIE 2001). Antibodies specific for Infectious Bursal Disease (IBD) vaccination were detected by qualitative agar gel precipitation test (AGPT). At week 6 of experiment, four birds (two males and two females) were randomly selected from each treatment and were sacrificed to compare the carcass characteristics using the standard procedures (Ricard & Rouvier 1967). The liver samples were collected and stored at −20°C until used for chemical analysis. Extraction of liver lipid was done by using the method as described by Folch et al. (1957). The sensory evaluation of meat samples was done by the method of Keeton (1983). Six breast meat samples of equal dimension from each treatment were collected for sensory evaluation.

Statistical analysis

The collected data was subjected to statistical analysis using Software Package for Social Sciences (SPSS Version 16.0) available in the Central library, Guru Angad Dev Veterinary and Animal Sciences, Ludhiana. The recorded data were subjected to one-way analysis of variance (Snedecor & Cochran 1980) with methionine source as the main effect. Comparison among means was made by Duncan‘s multiple range test (Duncan 1955) with significance level of P≤0.05.

Results and discussion

Growth performance

DL-M supplementation produced significantly higher body weight and weight gain with more feed consumption than HM-6 andHM-7 (Table 2). Similar trend was also observed for weight gain among birds supplemented with both types of herbal methionine. The FCR and EER were narrower and PER was higher with DL-M than HM-6 and HM-7 but with non-significant difference. The HM-6 and HM-7 were found only 91.9 and 92.3% bio-efficient, respectively, for weight gain in relation to DL-M (100%).

Table 2. Effect of DL-M, HM-6 and HM-7 on growth performance parameters and comparative efficacy.

	Treatments
Parameter	DL-M	HM-6	HM-7	SEM
Growth performance
Body weight, kg	2.20^a±0.023	2.03^b±0.025	2.03^b±0.029	0.05
Weight gain, kg	2.16^a±0.023	1.98^b±0.025	1.99^b±0.029	0.05
Feed intake, kg	4.13±0.09	4.00±0.09	3.84±0.05	0.07
FCR	1.91±0.02	2.01±0.03	1.93±0.06	0.03
PER	2.73±0.02	2.58±0.03	2.66±0.02	0.04
EER	5.61±0.06	5.91±0.09	5.65±0.02	0.08
Bio-efficacy for weight gain,%	100	91.9	92.3	2.64

Note: Means not sharing superscript, column wise, differ significantly (P≤0.05).

Carcass yield and organoleptic properties

Carcass yield and premier cut-up parts (Table 3) indicated no significant difference in evisceration yield, breast%, and leg% resulting from all the treatments.

Table 3. Effect of DL-M, HM-6 andHM-7 on the carcass and organoleptic properties.

	Treatments
Parameter	DL-M	HM-6	HM-7	SEM
Carcass characteristics
Evisceration rate,%	62.63±1.56	59.76±0.18	59.98±1.02	0.75
Breast,%	29.93±0.22	27.32±0.19	25.06±1.64	1.15
Leg,%	32.69±1.0	30.44 ±1.08	31.86±1.62	0.36
Organoleptic properties
Colour^a	6.42±0.26	6.29±0.22	6.33±0.26	0.03
Flavour^a	6.33±0.14	6.08±0.19	6.17±0.27	0.06
Juiciness^a	6.17±0.32	6.00±0.29	6.08±0.35	0.04
Tenderness^a	6.25±0.22	6.00±0.21	6.25±0.22	0.07
Overall acceptability^a	6.29±0.18	6.13±0.16	6.18±0.19	0.04

^a Score on 8 point scale.

The data on the organoleptic properties of breast meat (Table 3) indicated no significant difference in the colour score among different treatments. The flavour score was non-significantly higher in DL-M than both the HM-6 and HM-7. The juiciness score ranged from 6.00 in HM-6 to 6.17 in DL-M and again the difference in juiciness score among all the treatments was non-significant. The tenderness score ranged from 6.00 in HM-6 to 6.25 in DL-M and HM-7, but there was no significant difference among the treatment groups. The overall acceptability score for breast meat among the treatments ranged from 6.13 in HM-6 to 6.29 in DL-M. The difference in the overall acceptability score among all the treatments was non-significant.

Immune response and biochemical profile

Antibody titre (Table 4) in the sera samples of all the three groups ranged from 1.67 to 2.33. The birds treated with HM-7 showed higher titre than the other two groups. The level of albumin and immunoglobulin (Ig) in sera of HM-7 birds was almost similar to DL-M-fed birds, while, HM-6-supplemented birds had a slightly lower level of serum albumin, and Ig, the difference was, however, non-significant (P≤0.05) among all the treatments. The level of total protein in sera of DL-M- and HM-7-supplemented birds had a significantly higher value as compared to HM-6. The circulatory immune complexes (CIC) level in the serum was significantly (P≤0.05) higher in sera of HM-7 than DL-M- and HM-6-fed birds.

Table 4. Effect of DL-M, HM-6 and HM-7 on immune response and biochemical parameters.

	Treatments
Parameter	DL-M	HM-6	HM-7	SEM
Immune response
Haemagglutination titre against NDV, Log 2	1.667^b±0.272	1.667 ^b±0.544	2.333 ^a±0.272	0.22
Precipitation IBD	+	+	+	.....
Biochemical parameters
Albumin, g/dL	1.80±0.62	1.76±0.05	1.80 ±0.22	0.01
Total protein, g/dL	3.93 ^a±0.05	3.73 ^b±0.29	3.90^a±0.11	0.06
Circulatory immune complex, g/dL	1.74^c±0.30	1.85^b±0.27	1.96^a ±0.31	0.06
Immunoglobulins, g/dL	1.85±0.20	1.79±0.23	1.85±0.26	0.02
Liver lipids,%	4.54^c±0.07	4.82^a±0.03	4.75^b±0.02	0.08

Note: Mean values bearing different superscripts in a row differ significantly (P<0.05).

Liver lipids

The content of lipids in the liver tissue (Table 4) in DL-M was significantly lower than those of the HM-6 and HM-7 groups. The HM-7 further had a significantly lower content of lipids in the liver than HM-6.

There is either no or little relevant literature available in which synthetic and herbal sources of methionine were compared in poultry birds so far. Since the introduction of methionine hydroxy analogue (MHA), DL-methionine has been evaluated and compared for its efficacy with respect to growth and carcass yield in poultry birds.

As the herbal methionine contained natural methionine-rich plant materials, it might contain abundance of L-methionine. The L-isomer of methionine is present in natural sources of methionine (Ribeiro et al. 2005). D-methionine must be converted into L-form in order to be nutritionally active, and the conversion efficiency has been reported as 90% (Baker 1994). Since only L-isomers of methionine are used for protein synthesis, and the transport system for absorption has much lower affinity for the D-isomer than the L-isomer (Lerner & Taylor 1967), a better performance of birds fed the latter was expected. In the present study, the DL-M was a better source of methionine than HM-6 and HM-7 particularly, during the earlier growth period of 1–3 weeks of age as far as the weight gain, FCR, PER and EER were concerned (Figures 1–4). But during 4–6 weeks of age, the DL-M and HM-7 were equally effective for growth rate while HM-6 as well as HM-7 both were as effective for FCR, PER and EER as the DL-M. This difference in the performance parameters during the two phases of growth indicated that, as the age advanced, the broiler chicks established a mechanism for the effective use of methionine from the herbal sources. The weight gain was 12.4 and 17.2% lower, respectively, with HM-6 and HM-7 supplementation than DL-M during first 3 weeks of age. However, this difference narrowed down to 6.3 and 3.2%, respectively, for HM-6 and HM-7 compared to DL-M during 4–6 weeks of age, with no significant difference in FCR, PER and EER. For the overall growth period of 6 weeks, the HM-6 and HM-7 had 8.1 and 7.7% lower growth rate than DL-M, respectively, but had similar FCR, PER and EER to that with DL-M. Thus, the HM-6 and HM-7 were 87.4 and 82.8%; 93.7 and 96.8%; 91.9 and 92.3% bio-efficient for growth as compared to DL-M during 1–3, 4–6 and 1–6 weeks of age of broiler chicks, respectively. So, both HM-6 and HM-7 offer a good alternate particularly during 4–6 weeks of growth period. This confirms the findings by Demir et al. (2003) as they also reported that the natural feed additives may be used effectively as a herbal growth promoters for broilers. Little variations in the growth performance, FCR and EER of broilers with different sources and forms of methionine have also been reported in earlier studies (Baker & Boebel 1980; Elkin & Hester 1983; Garcia & Llaurado 1997; Garcia et al. 2000; Venegas et al. 2004; Bunchasak & Keawarun 2006). Nevertheless, Waldroup et al. (1981) did not observe difference between HMB 2-hydroxy-4- methyl-thio-butanoic acid), DL-M and L-methionine. Gou et al. (2000) have demonstrated that herbs and herbal sources of methionine have a positive effect on broiler growth performance. Ribeiro et al. (2005) reported that there is no influence of both the sources of methionine on carcass assessments, when the negative control (No methionine supplementation) treatment was compared to the other treatments (DL-M, L-Meth, HMB). He also observed that birds supplemented with HMB in the thermo neutral environment (25°C) had higher leg weight than those fed with DLM. In the present study also, there were non-significant differences for various carcass characteristics like carcass yield, breast% and leg%. Hassan et al. (2003) reported that methionine supplementation alone or along with feed additive supplements significantly improved the values of serum total protein, albumin and globulin. Ali and Mayah (2006) also concluded that better immune response could be obtained with adequate supplementation of methionine which had been identified to be in marginal quantities in poultry feed. Since the birds attained the age of 6 weeks, when bursa of fabricius started regressing, the diet might play role in the antibody genesis. Higher antibody titre in HM-7-fed birds might be due to the reason that the herbal preparations were good stimulant of immune response.

Figure 1. Average weight gain at 3 and 6 weeks of age.

Figure 2. FCR at 3 and 6 weeks of age.

Figure 3. PER at 3 and 6 weeks of age.

Figure 4. EER at 3 and 6 weeks of age.

The overall titres in all the three treatments were suggestive of the fact that the synthetic preparations might be responsible for the generation of some inhibitory components, which might interfere with the immunoglobulin production. However, as the herbal products or preparations had lower toxicity for the host system and adequate absorption, they may have better capability to reach the target organ without much degradation by the host enzymes (Shukla et al. 2002). Borrel et al. (2000) also reported an increase in antibody titres by the use of herbal preparations in broilers. Nageshwara et al. (2003) reported the immunomodulatory effect of plant extracts in birds. Ansari et al. (2012) also indicated that phytogenic feed additives like Azardirachta indica have beneficial effects on the hematological, serum biochemical and immunity constituents thus on the overall growth and carcass performance of broiler chicks. Rehman et al. (2012) revealed no toxic effect of the feed supplemented with indigenously produced crude form of l-lysine with equal bioavailability, safety and efficacy in comparison to purified crystalline l-lysine (HCl) on broiler chicks. Increase in antibody titres, related to supplemental methionine was also reported by Tsiagbe et al. (1987a). The lipid content in liver was significantly higher in HM-6 than HM-7 and DL-M-fed groups. Bunchasak and Keawarun (2006) however, found no significant effect of methionine source on the chemical composition of the liver. However, these workers compared different sources of methionine (DL-methionine and DL-methionine hydroxyl analogue free acid) than those used in the present study.

The results of this study indicated that less weight gain was achieved with supplementation of Herbomethione®, but was found to be more effective in immunomodulatory functions, as it resulted in higher antibody titres against NDV and IBD vaccinations, and produced a significantly higher level of circulatory immune complexes (CIC) in sera along with similar content of albumin and immunoglobulin compared to DL-M. Thus, it is concluded that further studies are required for its recommendations as a good alternative to replace DL-methionine in broiler diet, especially, under the organic poultry production programmes.