Egg quality traits in chicken varieties developed for backyard poultry farming in India

M Niranjan, R P Sharma, U Rajkumar, R N Chatterjee, B L N Reddy and T K Battacharya

Project Directorate on Poultry, Rajendranagar, Hyderabad 500 030, India
niranjan_matam@yahoo.com

Abstract

The performance of egg quality traits of four chicken varieties i.e. Cross 1 (C₁), Cross 2 (C₂), Vanaraja (C₃) and Gramapriya (C₄) were evaluated to assess the effect of genetic group and age on important egg quality traits in the present study.

The analysis of the data on 1844 eggs revealed that the genetic group had significant effect (P<0.01) on all the traits studied at different ages. Significant higher egg weights were observed in Vanaraja and C₁ cross.  The shape indices ranged from 76.18 ± 0.14 in Vanaraja to 78.33 ± 0.06 in Gramapriya. The Haugh unit scores were between 74.64 ± 0.40 and 79.42 ± 0.30 indicating the superior albumin quality in rural varieties. The yolk weights were higher in Vanaraja and Gramapriya, the proven varieties for backyard farming.  The yolk indices ranged from 0.44 ± 0.003 to 0.46 ± 0.003 among the rural varieties. The shell thickness was significantly influenced by genetic groups, it varied between 0.394 in Gramapriya to 0.401 mm in C₁ cross. The breaking strength was significantly higher (41.79 ± 0.32) in Gramapriya. The better egg quality parameters in the rural varieties is a positive sign to withstand the handling damages in rural areas as the birds are maintained under free range system.

Key words: egg quality, Haugh unit, shell thickness, yolk index

Introduction

Backyard poultry farming is gaining wider importance and acceptance among the rural people as source of income generation and supplementary livelihood activity. The egg and meat quality are the most important factors for popularization of the backyard farming. Project Directorate on Poultry (PDP) has developed the varieties that are suitable for rural areas for backyard farming similar to the traditional poultry keeping in the villages. The rural varieties are popular and well accepted by the small landless farmers across the country.  The dual purpose variety, Vanaraja and egg type variety, Gramapriya developed by PDP are highly popular among the rural people of India as one of the income generating activity especially for the rural women. The evaluation of external and internal quality of the egg is essential as consumers prefer better quality eggs. Stadelman (1977) described egg quality as the characteristics of an egg that affect its acceptability to the consumers. Many factors influence the egg quality i.e., breed/ strain/ variety, temperature, relative humidity, rearing practices and season (Sauter et al 1954; Washburn 1990). The success of poultry farming largely depends on the total number of good quality eggs produced especially in layers and dual purpose birds. Though lot of work has been carried out on egg quality traits, the information on varieties developed and being popularized for backyard farming in rural and tribal areas are limited. The present study was aimed at assessing the effect of genetic group and age on egg quality traits in rural varieties developed for backyard farming.

Materials and methods 

The data on egg quality traits collected form four rural varieties (crosses) developed for backyard poultry at PDP, Rajendranagar, Hyderabad is used for present study. The four varieties namely, Cross1, a cross of broiler pure line 1 and a tinted egg layer; Cross 2,  a cross between broiler pure line 2 and a tinted egg layer, Vanaraja and Gramapriya. C₁ and C₂ crosses are to be released soon; hence the details of parentage were not given.

A total of 1844 eggs were collected from the above four genetic groups at different ages i.e. 24, 28, 32, 36 and 40 weeks and various external and internal egg quality traits were studied. The external characters like egg weight, length, width and breaking strength were measured. Thereafter the eggs were broken and the internal traits like yolk weight, colour, height, albumin weight were recorded using standard procedure. Egg weight, Haugh unit, albumin height and yolk colour were measured using egg quality tester (EMT 5200, Japan). Breaking strength was measured by universal testing machine (Shimadzu, Japan). All the parameters were estimated using standard procedures.

The data were analyzed as per standard methods (Snedecor and Cochran 1994). The effect of genetic group and age on the different egg quality traits was studied. The individual means among genetic groups and at different ages were tested by DMRT for their significance.

Results and discussions 

The findings are presented and discussed according to the genetic group for overall period, at 24 weeks, 32 weeks and 40 weeks of age. The analysis of variance revealed that the genetic group had significant effect (P<0.01) at different ages on all fifteen traits studied.

Egg weight

The effect of genetic group on egg weight was significant (P<0.01) at all ages. Vanaraja and C₁ cross had higher egg weights than other genetic groups (Table 1).

Since egg weight is highly heritable trait the differences among the crosses might be expected among genetically different rural varieties. The average egg weight ranged from 50.94 ± 0.35 g (Gramapriya) to 52.97 ± 0.28g (Vanaraja) in different genetic groups. During the early production (24 weeks), C₁ and  C₂ recorded significantly (P<0.01) higher egg weights than Vanaraja and Gramapriya (Table 2).

At 32 weeks of age C₁ cross had higher egg weights (P<0.01) and at 40 weeks of age, C₁ and Vanaraja performed significantly better than the other two crosses (Table 3).

In general the egg weight of desi (indigenous) birds is low compared to exotic layers or broilers, but the egg weight in rural crosses studied was as good as the exotic varieties/ strains as observed in the present study. This might be due to utilization of exotic germplasm for the development of these rural varieties (Sharma et al 2006). Egg weight variations in different genetic groups were reported by many authors (Washburn 1990; Padhi et al 1998; Chatterjee et al 2007a). The egg weights at 64 weeks in White Leghorn control line were comparable to the rural varieties studied (Chatterjee et al 2007a). Similar egg weights were observed in White Nicobari fowl (52.45 ±1.72) whereas lower in Brown, Black Nicobari and higher in Naked neck and White Leghorn (Padhi et al 1998). Parmar et al (2006) and Singh et al (2000) observed lower egg weights 40.87 to 45.41g in Kadaknath and 41g in Aseel from India under field conditions. Mathivanam and Selvaraj (2003) reported higher egg weight (60.23g) in IWH as compared to the varieties in the present study. The egg weights gradually increased as age increases showing the positive correlation between egg weights and age.

Shape index

Shape index is the ratio of the width to length of the egg. The average shape index values recorded ranged from 76.18 ± 0.14 in Vanaraja to 78.13 ±0.19 in C₁ cross. The genetic group had significant (P<0.01) effect on the shape index, egg length and egg width at all ages (Tables 1 to 4). The shape index of C₁ cross was significantly (P<0.01) higher than the other three crosses at 24 weeks of age (Table 2). At 40 weeks of age C1 cross had significantly higher (78.88) and Vanaraja had significantly lower (75.67) shape indices (Table 3).

The shape indices of C₁ cross and Gramapriya had no significant difference. Lower shape indices of 74.35 and 75.52 were reported by Parmar et al (2006) in Kadaknath and Shakuntaladevi and Reddy (2004) in White Leghorn layers, respectively. Chatterjee et al (2006) observed higher shape index, 80.76±1.32 for IWK and lower indices for IWI (73.77±3.08) and  IWH (72.67±7.56) strains of White Leghorn. Similar shape indices were observed among some of the indigenous poultry breed of Andaman (Chatterjee et al 2007a). Padhi et al (1998) reported lower shape indices in White, Brown, Black Nicobari birds, Naked neck and White Leghorn compared to the crosses studied in the present study.

Haugh unit

Haugh unit is the measure of albumin quality which determines the quality of the egg. The average Haugh unit ranged form 74.64 ± 0.40 (Gramapriya) to 79.42 ± 0.30 (Vanaraja) among the genetic groups (Table 1). Genetic group had significant (P <0.01) effect on the Haugh unit (P<0.01) at all ages. At 24 weeks of age Haugh unit scores were significantly (P<0.01) higher in C₁ and Vanaraja than the other two crosses (Table 2). C₂ and Vanaraja performed significantly better than the other crosses at 32 weeks of age (Table 4). At 40 weeks C₁ had better Haugh unit scores compared to other crosses (Table 3). Similar Haugh unit values of 75.15 (Nicobari) and 73.16 (Naked neck) were reported by Padhi et al (1998). Parmar et al (2006) observed wide range of Haugh unit value for Kadaknath birds starting form 62.58 to 90.00 from India under field conditions and the Haugh unit values in the present study are with in the range. Chatterjee et al (2006) also reported lower Haugh unit values, 59.62 to 71.62 form the White Leghorn strains. The higher Haugh unit values indicated the superior quality of the albumin in rural varieties studied. The presence of exotic inheritance in rural varieties might be the reason for higher Haugh unit score in the present study.

Albumin weight

The albumin weight varied from 28.61 ± 0.27g to 31.13 ± 0.18g in rural crosses. The albumin weight differed significantly (P<0.01) among the genetic groups except in C₂ cross and Vanaraja which were similar statistically. Albumin weights at 24 weeks of age were significantly (P<0.01) higher in C₁, C₂ and Vanaraja varieties (Table 2). At 32 weeks, C₁and C₂ crosses had significantly better albumin weights than Vanaraja and Gramapriya (Table 4), whereas at 40 weeks C₁ cross had significantly (P<0.01) higher albumin weights than the other 3 crosses (Table 3). Parmar et al (2006) reported 20.74g in Kadaknath birds which was significantly lower than the present findings. Lower albumin weights (23.46 to 26.67g) than the present study were recorded by Chatterjee et al (2007a) in indigenous fowls of Andaman.  The rural varieties studied were the crosses of synthetic and improved chicken varieties which might be the reason for the better albumin weights.

Yolk index

Yolk index values were significantly influenced by the genetic groups (P<0.01) at all ages. The yolk indices ranged from 0.44 ± 0.003 (C₂ cross) to 0.46±0.03 (C₁ cross) across the genetic groups (Table 1). The yolk indices among C₂ cross and Vanaraja were similar without any significant variation. The yolk indices were significantly higher in Vanaraja at 24 weeks of age, C₁ and C₂ crosses at 32 weeks of age and Gramapriya at 40 weeks of age respectively.  Similar yolk indices 0.41±0.01 to 0.45±0.01 in Nicobari varieties of Andaman were observed by Padhi et al (1998). Chatterjee et al (2007a) reported lower yolk indices among six breeds of indigenous chicken of Andamans than the present rural varieties. Parmar et al (2006) also observed lower yolk index (0.37) for Kadaknath birds.  

Yolk weight

Yolk weight in the crosses varied from 16.17 ± 0.14g in C₂ cross  to 17.42 ± 0.14 g in Vanaraja which differed significantly in all the varieties studied (P<0.01) at different ages.  Yolk weight at 24 weeks of age were significantly higher (P<0.01) in Gramapriya birds (Table 2), at 32 weeks of age C₁ cross had significantly higher yolk weight (Table 4) and at 40 weeks C₁, C₂ cross and Vanaraja had significantly better yolk weights than Gramapriya (Table 3). A lower estimate of yolk weight (15.18g) was observed in Kadaknath (Parmer et al 2006) than the present study. Chatterjee et al (2007a) reported higher yolk weights in Naked Neck, Barred Desi and Frizzle Fowl and lower yolk weights in Brown and black Nicobari breeds of Andaman than the present rural crosses.  Similar yolk weights in reciprocal crosses of ILI 80 and Brown Nicobari crosses were observed by Chatterjee et al (2007b). The yolk percentage in different rural varieties were 31.27, 31.26, 32.88 and 33.06 in C₁cross, C₂ cross, Vanaraja and Gramapriya crosses respectively. Vanaraja and Gramapriya, proven varieties for backyard farming had higher yolk percentage. The rural varieties studied were the crosses of improved chicken varieties which might be the reason for the better yolk weights observed in the present study.

Yolk colour

Yolk colour was significantly (P<0.01) effected by rural crosses. The colour values varied between 7.49± 0.04 in C₂ cross and 8.01 ± 0.05 in Vanaraja. (Table1). Yolk colour estimates were significantly (P<0.01) higher in Gramapriya at 24 weeks of age, in Vanaraja at 32 weeks of age and in C₁ cross at 40 weeks of age respectively.

Shell thickness

The shell thickness varied significantly (P<0.01) among different genetic groups. Gramapriya and C₂ had similar shell thickness without any significant variation. The shell thickness was more in C₁ (0.401mm) and less in Gramapriya (0.394mm). The shell of C₁ cross was significantly (P<0.01) thicker than the other three crosses at 24 weeks of age (Table 2). Vanaraja birds had better shell thickness at 32 weeks of age (Table 4) whereas; C₁ and C₂ crosses were significantly higher shell thickness than the other two crosses (Table 3).

The mean shell thickness of 0.31mm in Kadaknath (Parmar et al 2006) and 0.33 in Nicobari, 0.31 in Naked neck and White Leghorn (Padhi et al 1998) were less than thickness observed in the present study. The higher shell thickness in the birds developed for backyard poultry was a better indicator for their suitability for rural/ backyard/free range farming. Wani et al (2007) reported lower shell thickness (0.32mm) for Vanaraja birds than the present study. Non significant variation in shell thickness between reciprocal crosses of ILI 80 and Brown Nicobari was observed by Chatterjee et al (2007b)

Shell weight

Shell weight significantly (P<0.01) affected by genetic groups at 24, 32 and 40 weeks of age (Table 2-4).  The shell weight for the overall data did not show any significant variation. The shell weight ranged from 5.24 in C₂ to 5.28 g in Vanaraja (Table 1). Shell weights were significantly higher in C₁ and C₂ cross at 24 weeks; C₁, C₂ and Vanaraja at 32 weeks and 40 weeks, respectively.  Non-significant differences were observed in Nicobari, Naked Neck and White Leghorn breeds for shell weight (Padhi et al 1998). Chatterjee et al (2007a) also reported the non significant breed difference in shell weight for six indigenous chicken breeds from Andamans.

Breaking strength    

Breaking strength is the ability of egg shell to withstand externally applied force. The strength depends on the type of material and organic components of the shell. The breaking strength ranged from 37.45 ± 0.34 Neutons (Vanaraja) to 41.79 ± 0.32 Neutons (Gramapriya) with significant difference in strength (Table 1). The C₁ cross and Vanaraja had different shell breaking strengths but statistically  not significant. Gramapriya recorded significantly (P<0.01) higher breaking strength at 24, 32, and 40 weeks of, a desirable character for an established rural chicken variety. Chatterjee et al (2006) reported lower breaking strengths (25.17 ± 0.11 to 31.07 ± 0.8) than the present study in White Leghorn strains.

Conclusions

• The study indicated that there was significant effect of genetic group on different egg quality traits.

• The performance of egg quality traits in rural varieties evaluated was comparable to the developed varieties.

• Some egg quality traits (i.e., shell weight, shell thickness and breaking strength) were better in the eggs of these rural varieties than that of exotic layers.  

• These egg quality characteristics of rural crosses are desirable to with stand the handling pressures under free range farming in rural and tribal villages of India.

References           

Chatterjee R N, Rai R B, Kundu A, Senani S and Sundar J 2007a Egg quality traits in indigenous breeds of chicken of Andaman; Indian Veterinary Journal 84 (2): 206-208

Chatterjee R N, Rai R B,  Pramanik S C, Sundar J, Senani S and Kundu A 2007b Comparative growth, production, egg and carcass traits of different crosses of Brown Nicobari with White Leghorn under intensive and extensive management systems in Andamans, India; Livestock research for Rural Development 19(12). http://www.lrrd.org/lrrd19/12/chat19193.htm

Chatterjee R N, Sharma R P, Niranjan M, Reddy B L N and Mishra A 2006 Genetic studies on egg quality traits in different White Leghorn populations; Indian Journal of Animal Genetics and Breeding 27(1,2): 51-54

Mathivanan R and Selvaraj P 2003 Influence of dietary chromium on egg production and quality parameters in layers; Indian Journal of Poultry Science 38:51-53

Padhi M K, Rai R B, Senani S and Saha S K 1998 Assessment of egg quality characteristics in White Leghorn layers; Indian Journal of Poultry Science 33: 113-115

Parmar S N S, Thakur M S, Tomar S S and Pillai P V A 2006 Evaluation of egg quality traits in indigenous Kadaknath breed of poultry; Livestock research for Rural Development 18(9). http://www.lrrd.org/lrrd18/9/parm18132.htm

Sakunthaladevi K and Reddy P M 2004 Effect of strain on physical egg quality characteristics in White Leghorn layers; Indian Journal of Poultry Science 39: 190-192

Sauter E A, Homs J V, Stadelman W J and Melaren B A 1954 Seasonal variation in quality of eggs measured by physical and functional properties; Poultry Science 33: 519-524

Sharma R P, Chatterjee R N and Niranjan M 2006 Poultry production under backyard system: Improvement approaches. In: National symposium on conservation and improvement of animal genetic resources under low input system; Challenges and strategies, NBAGR, Karnal. PP 72-77

Singh V, Gupta R K, Singh M and Gurung B S 2000 Reproduction and production performance of Aseel an indigenous breed of chicken; Indian Journal of Poultry Science 35: 200-204

Snedecor G W and Cochran W G 1994 Statistical methods; Affliated East-West Press and Iowa State University Press. 8^th edition.

Stadelman W J 1977 Quality identification of shell eggs; In egg science and technology; 2^nd edition, AVI Publishing Company Inc. Westport, Connecticut.

Wani S A, Malik A H, Bhat G A, Khan A A, Salahuddin Mir, Pal M A and Sofi A H 2007 In. Seminar on Backyard poultry farming for women empowerment and nutritional security cum Scientists – Poultry Farmers Meet, Organized by Sher-e-Kashmir University of  Agricultural Sciences and Technology of Kashmir, Srinagar

Washburn K W 1990 Genetic variation in egg composition. In: Poultry Breeding and Genetics pp 781-804. Crawford R D (Ed.), Elsevier Science Publisher, B V, Amsterdam, The Netherlands.

Received 18 August 2008; Accepted 29 August 2008; Published 5 December 2008

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