Effect of Genetic Groups and Gender on Body Weight and Different Morphometric Traits in Poultry Birds

India's chicken population grew by 16.81%, hitting a huge 851.81 million in 2019. Furthermore, backyard chicken experienced amazing growth, with a staggering 45.78% rise, reaching a total population of 317.07 million by 2019 (BAHS, 2022). There is a clear trend toward fragmented and small-scale poultry farming, which is shown by the rise in backyard chickens. In comparison, the commercial poultry sector saw a more moderate growth rate of 4.5%. Even though it grew at a slower rate, the number of commercial chickens hit a huge 534.74 million by 2019. This shows how important large-scale poultry operations are for meeting the growing demand for poultry products. These numbers show that India’s poultry industry is strong and flexible. They also show that the industry is growing in many different ways, from small backyard operations to bigger, more commercial poultry businesses.
       
Growth in poultry birds is a systematic process of developmental changes which involves protein deposition as well as increase in size and length of morphometric parts. Morphometric variations in traits could be important yardsticks of information in designing selection and genetic improvement programs for poultry birds, which primarily depends on the variations within and between breeds or populations. Moreover, body weight and body morphometric in chickens have been used in differentiating native from exotic as well as commercial breeds and in establishing phenotypic correlations among various genetic groups (Yakubu et al., 2009).
       
Body weight and morphometric traits have significant contribution to slaughter yield in poultry (Wolanski et al., 2006; Willemsen et al., 2008). Several studies have reported positive effect of these traits on marketable carcass weight (Mukhtar et al., 2013; Patbandha et al., 2017). Shank length has been reported to be significantly influencing the growth performance of poultry birds (Msoffe et al., 2001; Wolanski et al., 2006; Willemsen et al., 2008). Slow growing coloured birds (particularly indigenous breeds) have great demand due to their better meat quality in terms of appearance, less fat and taste as well as better performance in tropical climate (Jiang et al., 2007). There is need to study the effect of genetic groups and gender on morphometric traits and body weights in chickens as very scanty information is available especially in India.

The present investigation was carried out at Poultry Research Farm overseen by the Directorate of Livestock Farms, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana.  Three genetic groups of chickens i.e. Kadaknath, Rhode Island Red (RIR) and one native chicken germplasm (Punjab Brown) maintained under the AICRP on Poultry Breeding Project were included in the study. The healthy chicks were regenerated from the University hatchery and wing banding was done in the chicks for identification and data collection. Standard feeding and management practices were followed. Ad libitum feeding was done at chick stage with clean drinking water followed by restricted feeding through growing and laying stages of the birds. Every group is isolated in consistent feeding and uniform environmental circumstances. All the birds were vaccinated as per standard vaccination schedule covering important diseases viz. Marek¢s, Ranikhet/New Castle Disease (F₁, R2B and Lasota strains), Infectious Bursal Disease and fowl pox. Deworming was practiced every three months of age for prevention of parasitic infestations.
       
The data was collected on bodyweight and morphometric characteristics (300 birds; 100 from each breed and equally distributed among male and female). The study¢s data set covered the age span of 0 days to 26 weeks taken during the year 2023. Information on body weight (BW) was collected fortnightly intervals (hatch, 2^nd, 4^th, ……26^th week). Phenotypic data on different morphometric traits viz. body length (measured from tip of beak to tip of tail excluding feathers); shank length (The distance between the hock joint and the metatarsal pad on the tarsal-metatarsus); shank width, beak length (from widest point closer to the base of the beak to the end of beak); comb length (beak to the end of the combs); keel length (The sternum’s length i.e. distance between the vertices of the sternum); wing length (The distance between the tips of the phalanges and the shoulder joint) and breast girth (circumference of the breast around the deepest part of the breast) were measured as per guidelines of FAO (2012) and recorded biweekly from 12^th,14^th,…..upto 26^th weeks of age.
 
Statistical analysis
 
The following mathematical model was used for determining the effect of genetic groups and sex using IBM-SPSS 24.0 statistical package (IBM Corp, 2016):
   
Where:
m: The grand mean.
Y_ijk: The observations (of morphometric traits and body weight) on the k^th bird belonging to genetic group i (=1 to 3) and sex j (=1 to 2).
G_i and S_j: Fixed effects of genetic group and sex, respectively.
e_ijk: The error term assumed to be normally distributed (NID), assuming N~(0, 1).

Least squares means along with their standard errors for different non-genetic factors affecting body weight (gm) and various morphometric traits (cm) at different ages in RIR, Kadaknath and Punjab brown poultry birds are presented in Table 1 and Table 2.
 

 

 
Effect of genetic groups
 
Significantly higher (p≤0.01) body weight at different ages during 0 day to 26^th week of age was observed in Punjab Brown poultry birds in comparison to other studied genetic groups. This could be attributed to better adaptability of Punjab Brown birds to local climatic conditions as compared to other two breeds and continuous evaluation and improvement through selection being carried out at the farm. In the morphometric traits, body length (BL) was significantly higher (p≤0.01) in Punjab Brown from 12 to 18 week of age, after that RIR birds shows higher value of BL from 20 to 26^th week of age. However, Weimer et al., (2020) reported that slow growing (SG) broilers had better body length than conventional (CONV) strain (P<0.0005) as well as different other strain×stocking density combinations (P=0.03). Shank length (SL) measurement was significantly higher (p≤0.01) in RIR poultry birds at all age groups except at 12^th week of age which was higher in Punjab Brown birds. Similar findings were reported by Fayeye et al., (2014) who found significant differences (P<0.05) in shank length and body length values between the Isa Brown and Ilorin ecotype birds. Shank width (SW) was significantly higher (p≤0.01) in Punjab Brown in initial weeks (12^th week to 16^th week of age). In subsequent ages, RIR birds showed higher measurement for SW. Similar findings were reported by Shafiq et al., (2022); Ahmad et al., (2019); Oleforuh-Okoleh et al., (2017) and Liyanage et al., (2015) who observed significant difference (P<0.05) in shank width between different poultry genotypes. The measurement for beak length (BKL) was significantly higher (p≤0.01) at all age groups in Punjab Brown poultry birds. Our findings were supported by Tyasi et al., (2021) who found Hy-line layers having better (p<0.05) keel length, shank circumference and beak length as compared to Potchefstroom Koekoek birds. Comb length (CL) was significantly higher (p≤0.01) in RIR birds for all age groups (14^th to 26^th week) except 12^th week CL was higher in Punjab Brown birds. For keel length (KL), wing length (WL) and body girth (BG); Punjab Brown birds showed significantly higher (p≤0.01) values at all different age groups from 12^th to 26^th week of age.
       
Pathak et al., (2015) studied two chicken breeds (Aseel and Kadaknath) from 0 day to 7^th week of age and found significantly (P<0.05) higher body weight in Aseel than Kadaknath in all age groups. However, in the present study Kadaknath poultry birds had significantly lower body weight in comparison to RIR and Punjab Brown birds in different age groups. Ahmad et al., (2019) analyzed morphometric traits of three chicken genotypes: Naked Neck and two crossbreeds (Rhode Island Red×Naked Neck=RNN, Black Australorp×Naked Neck=BNN). RNN had significantly (P=0.0009) higher body weight (1491.12±64.10 g) and keel length (10.66±0.15 cm). Pawankar et al., (2022) found that Giriraja birds showed significantly higher (p<0.01) biweekly body weight gain up to 16th weeks of age followed by Black Astrolorp and Kadaknath birds. However, in our study native (Punjab Brown) birds had significantly higher body weight in comparison to RIR and Kadaknath. Shafiq et al., (2022) examined the morphometric traits of four naked neck chicken phenotypes at 8 weeks of age. They found significant (P<0.05) differences in keel length and shank circumference among different phenotypes. However, no significant difference was observed for body length and shank length among the different phenotypes. In our study, Punjab Brown birds had significantly higher values for different studied morphometric traits except shank length, width and comb length which had higher values in RIR poultry birds. Fadare (2014) found significant differences (P<0.05) in KL at 12 weeks of age among Naked Neck, Frizzled Feathered and Normal Feathered Crosses with Exotic Giriraja Chickens.
 
Effect of gender
 
Male birds had significant (p≤0.01) higher body weight as compared to female birds from 4^th to 26^th week of age. Significant (p≤0.05) difference was observed in day old chicks which could be due to difference in egg weight of different breeds; whereas the difference was non-significant at 2^nd week of age which may be due to poultry birds of different genetic groups taking some time to express their full genetic potential. Male chickens consistently exhibit significantly (p≤0.01) higher body lengths(BL),Shank length (SL), shank width (SW), beak length (BKL), comb length (CL), keel  Length (KL), wing length (WL) than females across all age groups except body girth (BG) which was non-significantly at 26^th week of the age and female had better average of 26^th week BG which may be due to birds reaching the age of egg production at that age.
       
Fayeye et al., (2014) studied equal no of male and female of Isa brown and llorin-ecotype chicken and found male chicken had significantly higher (p<0.05) matured body weight than female birds. Fadare (2014) studied naked neck, Frizzled Feathered and Normal Feathered Crosses with Exotic Giriraja Chickens and observed males have significantly (p<0.01) higher body weight, breast girth and keel length values compared to female birds at 12 week of age. In agreement to our findings, Desha et al., (2016) studied indigenous chicken under village condition of Bangladesh from 1^st week to 15^th week of age and found body weight was significantly (p<0.05) higher in male birds compared to female across all age groups.  Melesse et al., (2021) studied adult indigenous chickens of both sexes and observed male  had significantly (p<0.005) higher values for  Live weight (LW),body length (BL),keel length (KL) and wing length WL than female. Usman et al., (2021) studied two genotypes RNN (Rhode Island Red×Naked Neck) and BNN (Black Australorp×Naked Neck) obtained by two self-crosses (RNN×RNN = RR and BNN×BNN = BB) and two reciprocal crosses (RNN×BNN = RB and BNN×RNN=BR) RB and BR, males showed higher (p<0.01) drumstick length and drumstick circumference for both RB and BR genotypes compared to females of both genotype. Our study also certifies that males had higher values for body weight and morphometric traits in different age groups.

We conclude that Punjab Brown poultry birds had significantly higher (p≤0.01) body weight in different ages in comparison to Rhode Island Red (RIR) and Kadaknath poultry birds. For most of the morphometric traits also native poultry birds had higher values. So, it can be propagated further as a preferred indigenous breed for meat production particularly in the local climatic conditions.

There is no conflict of interest.