Mini ReviewAbstract
Nine genetic groups of native chickens of Nigeria were generated from a 3 x 3 diallel mating involving the normal feathered (NF), frizzle feathered (FF) and naked neck (Na) local birds. A total of 97, 75 and 73 straight bred chicks were hatched for the respective genetic groups. Correspondingly, 132,151 and 153 chicks resulted from various crosses (normal and reciprocal) of the parental birds. Body weights were taken at hatch and subsequently at 4, 8, 12, 16 and 20 weeks of age. Heterosis were calculated and general combining ability (GCA) were computed based on the pedigree of the birds. Body weight varied significantly (p<0.05) among the genetic groups at the various ages of measurement. Crossbreeding improved body weight in the crossbred over the parental genotypes. Heterosis for body weight at 20 weeks of age were positive and ranged from 1.93 in the Na birds to 12.18 in the NF birds. General combining ability (GCA) were 1058.97, 1044.01 and 1123.04 in the NF, FF and Na genotypes respectively. Consequently, variability was least in the Na genetic group signifying a higher selection pressure on these birds in the savanna region of Nigeria. The FF birds had a good hybrid ability and a greater gene variation for BW than the NF and Na genotypes. The study noted that that using the Na males against the FF females will give a greater advantage for body weight at 20 weeks of age in the savanna region of Nigeria. It is therefore recommended that Na males be crossed with FF females in developing table birds for this region from the available local stock.
Keywords:Normal Feather; Frizzle Feather Naked Neck; Heterosis; Diallel Crossing; Body Weight
Mini Review
Despite the role of the Nigerian local chicken in stabilizing
the rural households and contributing its quota to meeting the
protein need of both urban, and peri-urban dwellers, they have
been rated to be poor in terms of meat and egg output. This has
been attributed to the poor genetic base or genetic handicap of
these birds. Researchers have consistently pointed to selection and
cross breeding as plausible ways of circumventing this handicap
and improving the productivity of the local birds. The underlying
assumption here is that cross breeding leads to highbrid vigour
(heterosis) in the F1 while selection increases the frequencies of
the desirable genes in the population. Theoretically, hybrid vigor is
inversely proportional to the extent of genetic similarities between
parental populations [1] and it is expected to be proportional to
the extent of heterozygocity of crosses [2]. It has been reported
that crossbreeding results in alteration of the genetic variance and
allows combining the valuable traits of parent lines in their progeny
[3]. These authors further reported that an objective evaluation of
the value of a given strain and its exact place in combinations is
performed on the basis of diallel cross experiments. A diallel cross
gives the possible set of combinations between different genotypes.
The combining ability analyses help to identify desirable
combiners that may be utilized to exploit heterosis [4]. Gardner et
al. [5] referred to the general combining ability (GCA) as the average
performance of a line, strain or genotype in hybrid combinations
with other lines. The variation in GCA is attributable to additive
genetic variance. Many reports showed that GCA and therefore additive variations were generally more important than dominance
in determining body weight at different ages [4,6-8]. It is common
knowledge in animal breeding that the phenotypic value of an
animal is the sum of its genetic makeup and the environmental
effect. While many researchers have reported on the performance
of the Nigerian local chickens in hybrid combinations elsewhere,
there is a dearth of information on this performance in the savanna
region of Nigeria. The current study is therefore designed to
provide baseline information on the GCA of three genetic groups
of the Nigerian local chickens in the savanna ecology with the aim
of identifying desirable combiners for choice of meat type chickens
in this region.
Materials and Methods
The experiment was carried in Makurdi – Nigeria. Makuirdi is located within the savanna region of the country. The experimental birds were generated from a controlled breeding population of parent stock involving three genetic groups of Nigeria local chickens in a diallel mating arrangement as shown in (Table 1). The parent stock were sourced from local markets within and around Makurdi. They were kept for an adaptation period of four weeks. Birds with signs of ill health were isolated and treated. All birds were vaccinated against the common endemic diseases in the region. At the end of the adaptation period, the birds were distributed randomly into breeding pens with a mating ratio of 1:10 male to female respectively. Eggs were collected and identified according to sire lines, incubated and hatched artificially using the electric incubator. The day-old chicks were properly identified by colour marking, using indelible dyes and brooded under standard conditions on deep litter for eight weeks. Compounded chick and grower mash containing 18% crude protein and 2800Kcal/kg metabolizable energy, and 15% crude protein and 2670Kcal/kg metabolizable energy were feed ad libitum during the brooding and rearing phases respectively. There was no restriction to water intake throughout the experimental period. Routine vaccination was carried out as recommended for the environment. Progressive increase in body weight in the genetic group was evaluated 4-weekly to 20 weeks of age of the birds using a digital weigh scale. Daily weight gain was calculated using the procedure described by Msofffe et al. [9].
Table 1: Diallel mating arrangement for generating of experimental (F1) birds.
Note; a = normal feathered genotype, b = frizzle feathered genotype, c = naked neck genotype
Purebred crosses (diagonal) = 1, 1; 2, 2 and 3, 3
Main crosses (above diagonal) = 1, 2; 1, 3 and 2, 3
Reciprocal crosses (below diagonal) = 2, 1; 3, 1; and 3, 2
Dailygrowthrate=W2−W1/N
Where: W1 is the initial weight.
W2 is the final weight.
N is the number of days (between W2 and W1).
Statistical Analysis
The general linear model procedure of SAS [10] statistical analysis software was used to evaluate the effect of genetic group on body weight gain. Paired comparison was carried out using the Duncan’s multiple range test [11]. The model used was used:
Yij= μ+ai+eij
Where
Yij = individual observation
μ = Overall group mean
ai = fixed effect of ith genetic group
eij = Residual error.
Heterosis for body weight in the genetic groups was computed
as described by Fairll [12].
Heterosis (%) = {AB − 1/2 (AA+ BB)}×100
Where:
AB = phenotypic value of the F1 crossbred (hybrid)
AA = phenotypic value of the F1 parent (male)
BB = phenotypic value of the F1 parent (female)
The general combining ability (GCA) for body weight in the
genetic groups was calculated using [13] procedure
Results and Discussion
The least square means of body weight from 4 to 20 weeks of age is presented in (Table 2). Body weights varied significantly between the genetic groups from the 4th to the 20th week of age. Results of crossbreeding revealed that the introgression of the frizzling gene into the Na genotype significantly p< 0.05) improved body weight at 4 weeks of age in the cross bred genotype over the individual parental genotypes. Similarly, crossbreeding the NF with the FF and Na genotypes resulted in significant (p <0.05) improvement in body weight at 4 weeks of age in the respective crosses over the parental straight bred genotypes. At 12 weeks of age and subsequently, the naked neck genotype showed a significantly (p<0.05) higher body weight when compared to its contemporaries. This is suggestive that full plumage cover and the associated stressing factors characteristic of the tropical environment could have set in between the 8th and 12th week of age. The naked neck birds tend to cope better with this challenge than the other two genotypes of the native chickens of the savanna region of Nigeria. In all the genetic groups, cross breeding resulted in significant (p<0.05) improvement in body weight over the straight bred genotypes.
Table 1: Least square means + sem of body weight (g) at various ages of the genetic groups.
Note: a,b,c…Least square means in the same column with different superscripts differ significantly (P < 0.05). NF (a) = Normal
feathered, FF (b) = Frizzle feathered genotype, Na (c) = Naked neck genotype
Purebred crosses (F1 genotypes) = aa, ab, bb, and cc
Main crosses (F1 genotypes) = ab; ac and bc
Reciprocal crosses (F1 genotypes) = ba; ca; and cb
(Table 3) presents the percent heterosis for body weight at hatch and 20 weeks of age in the genetic groups. Heterosis were positive and ranged from 2.13 to 12.19 per cent. The low heterosis for body weight in the F1 crosses involving the Na genotype may be a further confirmation of less genetic variability between the genetic groups and a dominating role of non-additive genes in the expression of this trait. General combining ability (GCA) was computed in the genetic groups (Table 4) at 20 weeks of age using the diallel analysis. Twenty weeks of age is selected as the baseline for the calculation of GCA because the birds approach sexual maturity at this age and therefore may not be marketed below this age. GCA was lower (1044.01) in the FF genotype than in the NF (1058.97) and naked neck (1123.24) birds. It can therefore be inferred that the FF genotype has a good hybrid ability and a greater gene variation for BW than the NF and Na genotypes. Consequently, the FF genotype has a comparative inferior performance as an individual whole (not in hybrid combination) for body weight than the other two genetic groups at 20 weeks of age. Selection pressure was higher in the Na birds in the savanna region of Nigeria leading to a comparative higher GCA and reduced variation than in the other genotypes. The consequence of this, is that there is a greater potential for improvement in body weight in the FF birds than in the NF and Na birds. Therefore, using the Na males against the FF females will give a greater advantage for body weight at 20 weeks of age in the savanna region of Nigeria. It is therefore recommended that Na males be crossed with FF females in developing table birds for this region from the available local stock.
Table 3: Heterosis for body weights at hatch and 20 weeks of age in the genetic groups.
Note: NF = Normal feathered, FF = Frizzle feathered genotype, Na = Naked neck genotype
Table 4: General combining ability (GCA) for body weights at various ages in the genetic groups.
NF-Normal feathered genotype. FF- Frizzle feathered genotype. Na- Naked neck genotype
References
- Willham RL, Pollak E (1985) Theory of heterosis. J Dairy Sci 68(9): 2411-2417.
- Sheridan AK (1981) Crossing breeding and heterosis. Anim. Breed Abstr 49 (3): 131 -141.
- Lalev MN, Mincheva M, Oblakova P, Hristakieva I Ivanova (2014) Estimation of heterosis, direct and maternal additive effects from crossbreeding experiment involving two White plymouth rock lines of chickens. Biotechnology in Animal Husbandry 30(1): 103-114.
- Mekki Dafaalla M, Yousif Ibrahimm A, Abdel Rahman MK, Wang JY, Musa HH (2005) Growth performance of indigenous x exotic crosses of chicken and evaluation of general and specific combining ability under Sudan condition. Int J Poult Sci 4(7): 468-471.
- Gardner CO, Eberhadt SA (1991) Sex-limited and maternal effect on growth in chickens. Poultry science 70(4): 709-718.
- Kim SC, SB Chung, DS Sul (1977) Study of an estimate of genetic combining ability of Leghorn strain crosses Can. J Anim Sci 67: 663-680.
- Singh BP, JS Kari, DS Dhir, PK Trehan (1983) Comparison of some physical carcass characteristics in pure and cross bred broilers ind. Vet J 60: 646-649.
- Adebambo AO, Ikeobi CON, Ozoje MO, Oduguwa OO, Adebambo Olufunmilayo AI (2011) Combining Abilities of Growth Traits Among Pureand Crossbred Meat Type Chickens Arch. Zootec 60(232): 953-963.
- Msoffe PLM, MMA Mtambo, UM Minga, JE Olsen, HR Juul Madsen, et al. (2004) Productivity and reproductive performance of the free-range local domestic fowl ecotypes in Tanzania Livestock Research for Rural Development 16(9): 2004.
- SAS (2008) User Guide: Statistics Release 9.2. - Statistical Analysis System Institute, Inc, Cary, North Caroline.
- Duncan DB (1955) Multiple range and multiple f test. Biometrics 11(1): 1-42.
- Fairfull RW (1990) Poultry Breeding and Genetics. Heterosis. In: Crawford RD (eds.) Elsevier, Amsterdam pp. 913-933.
- Griffing B (1956) Concept of general and specific combining ability in relation to diallel cross. Aust J Anim Sci 58 (4): 863-493.
