Effect of crossing two selected lines for early and lately age at sexual maturity on some growth and carcass traits in Japanese quail

Document Type : Original Article

Authors

1 Department of Animal Production, Faculty of Agriculture, Al-Azhar University, Nasr City, Egypt.

2 Department of Animal Production, Faculty of Agriculture, Al-Azhar University, Nasr City, Egypt

Abstract

A crossbreeding experiment was carried out using two selected lines of Japanese quail,( Early and Lately age at Sexual Maturity) (EASM&LASM lines were established for early and lately age at sexual maturity). A total number of 1310 crossbred birds of quail produced from two mating groups among three hatches were used for the present study to estimate direct heterosis, direct additive and maternal effects on the following traits: growth traits: body weight recorded at 0, 2, 4, 6 weeks of age (BW0, BW2, BW4, BW6) and average daily gain between the different growth period studied 0 - 2, 2 - 4, 4 - 6, 0 - 6 weeks of age (ADG0-2, ADG2-4, ADG4-6, ADG0-6).Carcass traits: Slaughter weight, meat, bone, giblets and dressing percentages (SW, M%, B%, G%, D%).
The results obtained can be summarized as follow:Crossing sires of EASM with LASM dams had the highest body weights and body weight gains recorded from hatch to 6 weeks of age followed by reciprocal crossing between sires of LASM with EASM dams., Highly significant positive direct heterosis effect for most body weights recorded at different ages was observed except BW4 and body weight gains calculated between different growths periods studied. , Crossing sires of EASM with LASM dams had the highest carcass performance followed by reciprocal crossing between sires of LASM with EASM dams., positive direct heterosis effect for most carcass traits studied was observed except M% and G% direct heterosis was non-significant

Keywords


Effect of crossing two selected lines for early and lately age at sexual maturity on some growth and carcass traits in Japanese quail

A. R. Shaban, D. I. Aboul-Seoud *, and M. A. Aboul-Hassan

Department of Animal Production, Faculty of Agriculture, Al-Azhar University, Nasr City, Egypt.

*Corresponding author E-mail: dr. deyabbreeding@azhar.edu.eg (D. Aboul-Seoud)

ABSTRACT

A crossbreeding experiment was carried out using two selected lines of Japanese quail,( Early and Lately age at Sexual Maturity) (EASM&LASM lines were established for early and lately age at sexual maturity). A total number of 1310 crossbred birds of quail produced from two mating groups among three hatches were used for the present study to estimate direct heterosis, direct additive and maternal effects on the following traits: growth traits: body weight recorded at 0, 2, 4, 6 weeks of age (BW0, BW2, BW4, BW6) and average daily gain between the different growth period studied 0 - 2, 2 - 4, 4 - 6, 0 - 6 weeks of age (ADG0-2, ADG2-4, ADG4-6, ADG0-6).Carcass traits: Slaughter weight, meat, bone, giblets and dressing percentages (SW, M%, B%, G%, D%).

The results obtained can be summarized as follow:Crossing sires of EASM with LASM dams had the highest body weights and body weight gains recorded from hatch to 6 weeks of age followed by reciprocal crossing between sires of LASM with EASM dams., Highly significant positive direct heterosis effect for most body weights recorded at different ages was observed except BW4 and body weight gains calculated between different growths periods studied. , Crossing sires of EASM with LASM dams had the highest carcass performance followed by reciprocal crossing between sires of LASM with EASM dams., positive direct heterosis effect for most carcass traits studied was observed except M% and G% direct heterosis was non-significant

Keywords: Crossing, early and lately age at sexual maturity, Japanese quail.

 

INTRODUCTION

Quails have the advantages of rapid growth rate, good reproductive potential, short life cycle, low feed requirements, good meat taste, better laying ability and shorter time for hatching as compared with different species of poultry, so it is considered as a pilot animal for poultry breeding investigations.

Crossing procedures usually lead to better economic performance due to the hybrid vigor, however crossbreeding is a very effective method for obtaining different recombination of genetic materials where it results in increased heterozygosis and tends to cover up recessive genes, decreases breeding purity and eliminates families in one generation. Breeding usually improve the performance of the different characters by selection and or crossing, to obtain different degrees of heterosis. That is to say, by directing the additive and non-additive genes to better performance of the different traits. The additive nature of genetic variation for growth has resulted in dramatic body weight improvement in Japanese quail (Marks, 1978 & 1990 and Nestor et al., 1982). Non additive genetic effect is important in meat and laying stocks because of the opportunitiestocombine stocks that complement each other. This allows development of mating combinations for rapid growth, yield and other important economic traits (Marks, 1995). Most available estimates of heterosis for body weight in Japanese quail were observed in reciprocal crosses of two quail lines, both selected for high body weight (Biak and Marks, 1993 and Marks, 1995) or crossing lines of high and low body weight (Gerken et al., 1988; Barden and Marks, 1989 and Marks, 1993).

The main purpose of the present study was to evaluate the importance of heterosis, maternal and direct additive effects arising from crossing two selected lines of Japanese quail for early and lately age at sexual maturity on some growth and carcass traits.

MATERIALS AND METHODS

Data used in the present study were collected on the flock of two lines of Japanese quail EASM&LASM(early and lately age at sexual maturity) were selected for early and lately age at sexual maturity maintained by the Department of Animal Production, Faculty of Agriculture, Al-Azhar University. Cairo, Egypt. Crossbreeding experiment was carried out using two selected lines of Japanese quail EASM x LASM, its reciprocal cross LASM x EASM.

Distribution of birds produced in each hatch and breed group are presented in Table (1).

Eggs were collected for hatch when the females were 10 to 12 weeks of age, marked, incubated for 15 days, after incubation the eggs were transferred to the hatcher and 3 days later all chicks were removed from the hatcher. Immediately after hatch individual quail birds were permanently identified by wing - bands and placed in quail battery brooders, where they remained for 4 week- period. All birds were housed in the same room for temperature, humidity, light intensity and other variables would be as similar as possible. However, environment and management practices were at conventional levels through the whole study. At 5 weeks of age the males were separated from the females and at 6 weeks of age, birds were divided into four groups. (EASM , LASM, EASM X LASM and LASM X EASM)

All birds were sexed according to plumage color and pattern at the same time, all chicks were taken and moved to individual laying cages and stud mating started about two weeks later. Feed and water were provided ad libitum. The experimental diet contained 28% protein and 2920 k cal. - ME/ Kg until two weeks of age and 25% protein with 2850 k cal. - ME/Kg during 3-6 weeks of age, then changed to a ration contained 20% protein with 2820 K cal. - ME / Kg during the egg production period.

Temperature started with 38°c for the first week after hatching, then decreased 2-3°c weekly to 26-28°c at the fourth week of age till the end of brooding period.

Statistical analysis:

Data of individual body weight, daily gains and carcass traits were analyzed using Henderson's Method III (Henderson, 1984) by using the following mixed model (Harvey 1990). 

Yikpmq = μ+ Gi +Sk+SEp+Hm+eikpmq    Where:

Yikpmq = the observation on the kpmq th trait;

μ = overall mean, common element to observations,

Gi            = fixed effect of the ith mating groups,

Sk           = random effect of kth sire, 

SEp         = fixed effect of the pth sex;

Hm       =fixed effect of the mth hatch,

eikpmq = random deviation of the qth growth and carcass traits distributed, i.e., N.D (0, σ2e). 

Crossbreeding components for growth and carcass traits were estimated according to Dickerson (1992),itwas used to analyze the crossbreeding data as:

Pure lines differences:

PU EASM x LASM = [(EASMxEASM) - (LASMxLASM)].

Direct heterosis effect: 

HI EASM x LASM = [(EASM x LASM) + (LASM x EASM) – (EASM x EASM) - (LASM x LASM)].

HI% = HI in units/0.5[(EASM x EASM) + (LASM x LASM)] x100.

Direct additive effect:

(GIEASM – GILASM) = [(EASMx LASM) + (EASM x LASM)]–[(LASM x LASM) + (LASM x EASM)].

Maternal additive effect:

(GM EASM – GM LASM) = (EASM x EASM) - (LASM x EASM) , where:

GI and GM represent direct additive and maternal additive effects, of the subscript breed (genetic) group.

RESULTS AND DISCUSSION

Crossbreeding effects:

Growth traits:

Least-square means and standard errors (SE) for body weights recorded at different ages and daily weight gain calculated among different growth periods studied are given in (Tables, 2 & 3). Crossing sires of EASM with LASM dams had the higher body weights and body weight gains recorded from hatch to 6 weeks of age followed by reciprocal crossing between sires of LASM with EASM dams. However, significant differences due to mating group on growth traits were observed.

Results of significant effect of MG on growth traits of Japanese quail strains were also confirmed by different authors (Larson et al., 1986; El-Naggar et al., 1992; Barbour and Liibum, 1995; Mandour et al., 1996; Bahie El-Deen et al., 1998; Sherif et al., 1998; Aboul-Hassan, 2001; Abdel-Ghany et al., 2004 and Nofal, 2006).

Direct heterosis:

Estimates of direct heterosis calculated in units (g) and percentages (%) for body weights recorded at different ages and body weight gains calculated among different growth periods studied are presented in (Tables, 2&3) However, these traits showedhighly significant positive direct heterosis effect for most body weights recorded at different ages was except BW4 and body weight gains calculated among different growth periods studied. Estimates of heterosis percentage for BW0 and BW2 (32.7 and 27.9%) declined to (19.8 and 18.9%) for BW4 and BW6.However, estimates of heterosis percentage for body weight gains were high at ADG0-2, ADG2-4 (15.9 and 14.3%) and declined to (9.9 and 6.7%) for ADG0-6 and ADG4-6.

Such superiority of cross lines quail over their parental lines points to considerable non-additive genetic line effects. In this respect, Bahie El-Deen et al. (1998) and Aboul-Hassan (2001) observed that heterosis contrasts were significant for BW0, BW2 and BW4 (P≤0.001) and BW6 (P≤0.01).

Maeda et al. (1988) and Sato et al. (1990) indicated the presence of heterotic effects in body weights of quail recorded at different ages. Marks (1995) crossing lines of quails selected long-term for increased body weight, but that was dependent on both environments and age as well as the genetic of populations. He crossed medium weight quails (selected for high BW4) and quails of heavy strain and reported that considerable heterosis was present for body weights.

Damme (1994) reported heterosis for BW1 to BW6 ranged between 0.6 and 2.7%, and it was significant for BW2. Bahie El-Deen et al. (1998) reported that heterosis percentage estimates for body weight were high at BW2 (30.2%) and declined to (11.8%) at BW6. Heterosis contrast were significant for BW2, BW4 (P≤0.001) and BW6 (P≤0.01) but non for ADG2-6. Furthermore, Bahie El-Deen (1994) and Nofal (2006) when crossing two lines of quails, one selected for high BW6 and the other line was selected for high egg production noticed negative heterosis for growth traits.

On contrary, Gerken et al. (1988) reported that heterosis was not significant for body weight from 25 to 49 days of age in Diallel crosses among two random bred control lines and a line selected for large body weight.

Direct additive effect:

Direct additive effect for all body weights recorded at different ages and all body weight gains calculated between different growth periods studied were significant and they were ranged between 5.66 for BW0 and 30.28 for BW4 and between 5.29 for ADG0-2 and 9.75% for ADG4-6 (Tables, 2&3).

The same trend was also concluded by Bahie El-Deen et al. (1998) and Nofal (2006). They reported that direct additive effect on body weight at market age of M-sired quails was significantly different from quails sired by E-line. Sire-line linear contrasts indicate that E-sired quails were significantly superior in BW6 (P≤0.05) and ADG2-6 (P≤0.01). At 4 weeks of age, direct genetic effects were also pronounced in favour of E-sires, while at early ages, M-sires were better than E-sires.

Aboul-Hassan (2001) reported that body weights and body weight gains of B sired quails were significantly different from quails sired by W strain. Sire-line linear contrasts indicate that W-sired quails were significantly superior in most growth traits studied (P≤0.01) except BW0 and BW2 was in favor of sired by B strain.

Maternal additive effect:

Maternal additive had a significant negative effect on most body weights recorded at different ages and body weight gains calculated between different growth periods studied, except BW0, BW2, ADG2-4 and ADG4-6 and they were ranged between -7.34 for BW4 and -8.77 for BW6 and between -4.18 for ADG0-2 and -5.23 for ADG4-6 (Tables, 2 & 3). However, it may be effective to use EASM quails as a line of dams in crossbreeding programs for producing quails with heavy weights and increased gains. The same trend was observed by Bahie El-Deen et al. (1998). An evidence for the significant maternal effects on body weight was obtained by Biak and Marks (1993). They reported significant reciprocal effects between the HW with LW and LW with HW crosses in Diallel crosses of Japanese quail lines divergently selected for BW.

On the contrary, Chahil et al. (1975) reported the absence of maternal effects in BW5 in a 3 x 3 Diallel cross of 3 random mating populations of quail. Nofal (2006) crossed M line (selected for meat production) and E line (selected for egg production) and reciprocal crosses reported that maternal additive had a non-significant effect on all growth traits (BW0, BW6 and ADG0-6). However, this insignificant influence of maternal additive could be expected since this component is being diminished as birds advance in age.

Carcass traits:

Least-square means and standard errors (SE) for carcass traits studied i.e., SW, M%, B%, G% and D% are given in (Table, 4). The crossbreds produced from sired EASM with LASM dams had the highest carcass traits except B% and the crossbreds produced from sired LASM with EASM dams had the lowest carcass traits except B%. However, significant differences due to mating groups (MG) on carcass traits were observed. The same trend was reported by Shalan (1998) and Adel-Mounsif (2005).

On the other hand, Sharaf et, al (2006) when they crossed three colored varieties of Japanese quails (Brown, Golden and White) stated that carcass traits did not express any significant values between purebreds, crossbred and reciprocals, while edible percentages were the highest in purebreds (8.99%).

Direct heterosis:

Positive direct heterosis effect for most carcass traits studied was observed except M% and G%. Direct heterosis was non-significant effect. Estimates of heterosis percentage for carcass traits were high for B% and SW % (22.9 and 19.6%) and declined to (12.0 and 12.8%) for M% and D% (Table, 4).

Direct additive effect:

Direct additive effect on all carcass traits studied were non-significant.  Estimates of carcass traits of quails in favor of EASM-sire to those quails sired by LASM line (Table, 4). The same trend was reported by Abdel-Mounsif (2005).

Maternal additive effect:

Maternal line effects (expressed as the differences between reciprocal crosses) on all carcass traits studied were non-significant. Estimates of carcass traits of quails in favor of sired by EASM line were to those quails mothered by LASM line (Table, 4).

CONCLUSION

Crossing of EASM line sires with LASM line dams was associated with an improvement in all growth traits, egg production and reproduction and carcass traits.

REFERNCES

Abdel-Ghany, A.M, Younis, H.H., Nofal, R.Y., 2004. Effect of crossing two Japanese-quail-lines selected seven generations for meat and egg production on growth traits. Agri., res., J. Suez Canal University, 3(1): 1-14 Ismailia, Egypt.

Aboul-Hassan, M.A. 2001. Crossbreeding effects on some growth and egg production traits among tow strains of Japanese quail (Coutrnix coturnnix japonica). Al-Azhar J. Agric. Res., Vol. 34 PP. 41-57.

Abdel-Mounsef, N.A. 2005. Crossbreeding effects on some productive and reproductive traits among selected lines of Japanese quail. Ph.D. Thesis, Thesis. Fac.  Agric. Al-Azhar Univ. Cairo, Egypt.

Bahie El-Deen, M. 1994. Selection index and crossing as a tool for improvement meal and egg production in Japanese quail. Ph.D. Thesis, Fac. of Agric; Alex. Univ. Egypt.

Bahie El-Deen, M., Shebl, M.K., EI-Raffa, A.M. 1998. Heterosis, maternal and direct genetic effects for growth and egg production traits in quail crosses. Egypt. Poult. Sci. 18:153-165.

Biak, D.H., Marks, H.L. 1993. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 7- Heterosis and combining ability among Diallel crosses following twenty-seven generations of selection. Poult. Sci. 72: 1449-1458.

Barden, J.R., Marks, H.L. 1989. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 3- Influence of selection for growth on heterotic effects for body weight, feed and water intake patterns. Abdominal fat and carcass lipid characteristics. Poult. Sci. 68: 34-45.

Barbour, G.W., Liibum, M.S. 1995. Characterization of growth development from 14 to 15 days of age in Japanese quail hens from two strains. Poult. Sci. 74: 1650-1658.

Chahil, P.S., Johanson, W.A., Schilling, P.E. 1975. Combining ability in a Diallel cross of three lines of coturnix japonica. Poult. Sci. 54: 1844-1949.

Damme, K. 1994. Growth of medium-weight and heavy strains of quail and the reciprocal crosses. Archiv-fureflugelkunde. 58: 34-37.

Dickerson, G.E. 1992. Manual for evaluation for breeds and crosses of domestic animals. Publications Division, FAO, Rome, Italy.

El-Naggar, N.M., Sharaf, M.M., Mandour, M.A. 1992. Relationship of growth yields and some body measurements in different Japanese quail strains. Egypt. Poult. Sci. 12: 145-164.

Gerken, M., Zimmer, S., Peterson, J. 1988. Juvenile body weight and gonad development in a Diallel cross among lines of Japanese quail (Coturnix japonica). Theor. Appl. Genet. 76: 775- 780.

Larson, J.E., Adams, R.L., Peng, I.C., Stadelman, W.J. 1986. Growth, feed conversion and yield of Japanese quail parts of three strains of hen Japanese quail as influenced by age. Poult. Sci. 65: 2076-2081.

Henderson, C.R. 1984. Application of Linear Model in Animal Breeding. University of Guelph Press. Guelph, Canada.

Harvey, W.R. 1990. Users guide for LSMLMW. Mixed Model Least Squares and Max­imum Likelihood Computer Program. PC. Version 2. Ohio State Univ., Columbus, USA (mimeograph).

Maeda, Y., Sato, K., Okamoto, S., Hashiguchi, T. 1988. Heterosis in body weight and muscle protein turnover rate in coturnix quail. Biuehem. Genet. 26: 395-399.

Mandour, M.A., Abd-Allah, G.A., Sharaf, M.M. 1996. Effect of crossbreeding on some growth traits of native and standard breeds of chickens. Egypt. Poult. Sci. 16 (1): 171-164.

Marks, H.L. 1978. Long-term selection four-week body weight in Japanese quail under different nutritional environments. Theor. Appl. Genet. 52: 105-111.

Marks, H.L. 1990. Abdominal fat and tests weights on diverse genetic lines of Japanese quail. Poult. Sci. 69: 1627-1633.

Marks, H.L. 1993. Divergent selection for growth in Japanese quail under split and complete nutritional environments. 6- Differential body weights in reciprocal crosses. Poult. Sci. 72: 1847-1854.

Marks, H.L. 1995. Heterosis and over dominance following long-term selection for body weight in Japanese quail. Poult. Sci. 74: 1730-1744.

Nestor, K.E., Bacon, W.L., Lambio, A.L. 1982. Divergent selection for body weight and yolk precursor in Coturnix japonica. 1. Selection responses. Poult. Sci. 61: 12-17.

Nofal, R.Y. 2006. Crossbreeding parameters of females in two lines of Japanese quail for some growth and sexual maturity traits.  Egypt. Poult. Sci. 26 (1): 69-85.

Sato, L., Fukuda, H., Maeda, Y., Hedianto, Y.E., Ino, T. 1990. Heterosis for growth in reciprocal crosses of highly inbred lines of Japanese quail. A.B.A. 58: No. 1812.

Shalan, H.M. 1998. Independent culling levels selection and crossing for improving meat and egg production in Japanese quail. Ph. D. Thesis, Fac. Agric., Alex. Univ.

Sharaf, M.M., Mandour, M.A., Taha, A.E. 2006. Effect of Diallel crossing on some growth performance, carcass traits and immune response against new castle disease virus vaccine of Japanese quail.  Egypt. Poult. Sci. 26 (4): 1451-1470.

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Table 1.Distribution of birds produced from crossbreds among different lines and hatches.

Total

LASM X EASM

EASM X LASM

Mating groups

F

M

F

M

F

M

Hatch

237

218

205

210

240

200

110

100

105

105

115

95

127

118

100

105

125

105

1

2

3

660

650

315

315

345

335

Total

M: Males, F: Females.

Table 2. Least-square means of body weight traits between different mating groups ± SE, heterosis (HI), maternal additive effect (GM) and direct additive effect (GI). 

BW6

BW4

BW2

BW0

No.

 

Mean ± SE

Mean ± SE

Mean ± SE

Mean ± SE

 

Mating groups:

191.7 ± 8.76

109.2 ± 6.06

53.5 ± 6.04

9.8 ± 0.32

475

EASMx LASM

181.9 ± 7.80

100.3 ± 7.55

48.4 ± 4.11

9.0 ± 0.51

390

LASMx EASM

19.24 ± 1.37***

2.53 ± 9.83ns

8.91 ± 2.90**

10.23 ± 3.50***

 

Pure breed effect

22.42 ± 1.88***

1.78 ± 3.95ns

15.86 ± 1.24***

6.54 ± 3.14*

 

Direct heterosis (Hi)  Unit

18.9%

19.8 %

27.9 %

32.7 %

 

Percentage

27.37 ± 1.88***

30.28  ± 4.54*** 13.55***

9.98 ± 1.24**

5.66 ± 2.44**

 

Direct additive effect (Gi)

-8.77 ± 1.30***± 4.54

-7.34 ± 9.33*

3.20± 0.86ns

2.35 ± 3.50ns

 

Maternal additive effect (Gm)

 *=P≤ 0.05or **= P≤ 0.01or ***= P≤ 0.001, ns=Non- significant.

 

 

 

Table 3. Least-square means of daily weight gain traits between the different mating groups ± SE, heterosis (HI), maternal additive effect (GM) and direct additive effect (GI).

ADG0-6

ADG4-6

ADG2-4

ADG0-2

No.

 

Mean ± SE

Mean ± SE

Mean ± SE

Mean ± SE

 

Mating groups:

4.8 ± 0.04

6.9 ± 0.71

4.4 ± 0.47

2.8 ± 0.89

475

EASMx LASM

4.0 ± 0.04

6.4 ± 0.90

4.1 ± 0.99

2.5 ± 1.09

390

LASMx EASM

9.48 ± 0.04***

6.01 ± 0.09*

10.35 ± 0.71***

9.36 ± 0.08***

 

Pure breed effect

10.24 ± 0.06***

1.81 ± 0.13***

8.40 ± 0.53**

10.15 ± 0.10***

 

Direct heterosis (Hi)  Unit

6.7%

9.9 %

14.3 %

15.9 %

 

Percentage

7.51 ± 0.06**

9.75 ± 0.45**

6.66 ± 0.17**

5.79 ± 0.15**

 

Direct additive effect (Gi)

-0.16 ± 0.27 n.s

-5.23± 0.39*

-0.15 ± 0.13ns

-4.18 ± 0.27*

 

Maternal additive effect (Gm)

 *=P≤ 0.05or **= P≤ 0.01or ***= P≤ 0.001, ns=Non- significant.

Table 4. Least-square means of carcass traits among the different mating groups ± SE, heterosis (HI), maternal additive effect (GM) and direct additive effect (GI).   

D%

G%

B%

M%

SW

No.

Traits

Mean ± SE

Mean ± SE

Mean ± SE

Mean ± SE

Mean ± SE

 

Mating groups:

74.0 ± 6.08

8.9 ± 3.12

13.0 ± 9.20

65.3 ± 6.47

192.7 ± 3.45

6

EASMx LASM

72.8 ± 7.38

7.6 ± 4.70

13.9 ± 7.86

63.8 ± 7.22

183.5 ± 3.77

6

LASMx EASM

-1.3± 1.31ns

-1.2 ± 0.45ns

-0.8 ± 6.02ns

-10.5 ± 8.65**

-24.5 ± 5.43***

 

Pure breed effect

8.5 ± 1.85**

1.9 ± 0.63ns

6.8 ± 8.52**

2.7 ± 6.99ns

28.8 ± 7.69***

 

Direct heterosis (Hi)  Unit

12.8

13.5

22.9

12.0

19.6

 

Percentage

-2.0 ± 4.80ns

-6.7 ± 0.63*

-9.2 ± 3.82**

-20.0 ± 7.96***

-31.7 ±11.69***

 

Direct additive effect (Gi)

1.2 ± 3.39ns

2.2 ± 0.45ns

6.3 ± 5.72**

10.5 ± 5.63***

21.0 ± 10.46***

 

Maternal additive effect (Gm)

   *=P≤ 0.05or **= P≤ 0.01or ***= P≤ 0.001, ns=Non- significant.

 

تأثيرالخلط بين خطين منتخبين لصفة النضج الجنسى المبکر والمتأخرعلى بعض صفات النمو وصفات الذبيحة فى السمان اليابانى

أحمد رجب على شعبان ,محمد أبو الحسن أحمد حسن ودياب ابراهيم محمد أبو السعود *

قسم الإنتاج الحيواني, کلية , الزراعة, جامعة الأزهر, القاهرة.

* البريد الالکتروني للباحث الرئيسي: deyabbreeding@azhar.edu.eg

الملخص العربي:

تم إجراء تجربة خلط بإستخدام خطين منتخبين من السمان اليابانى لمدة أربعة أجيال : الخط الأول منتخب لصفة النضج الجنسى المبکر(EASM). الخط الثانى منتخب لصفة النضج الجنسى المتأخر(LASM). تم خلط ذکور الخط (EASM) مع إناث الخط (LASM) والتلقيح العکسى بين الخطين. تم أخذ عدد 1310 طائر خليط  تم إنتاجها خلال ثلاث فقسات متتالية وذلک لتقييم الأداء الإنتاجى وصفات الذبيحة فى الطيور الخليطة وقياس تأثير کل من الخلط والتأثيرات المضيفة المباشرة والأمية على الخلطان للصفات الآتية: صفات النمو وتشمل: أوزان الجسم عند عمر الفقس و 2 و 4 و 6 أسابيع ومعدلات النمو اليومية خلال الفترات الآتية : صفر-2 و 2-4 و 4-6 و صفر-6 أسبوع . وصفات الذبيحة وتشمل: وزن الذبح والنسب المئوية لکل من اللحم – العظم – الأجزاء المأکولة – التصافي في ذبائح السمان الياباني .وقد أوضحت الدراسة النتائج الآتية : بالنسبة لصفات النمو :صاحب الخلط بين ذکور (EASM) وإناث (LASM) تفوق فى صفات أوزان الجسم عند الأعمار المختلفة وکذلک فى صفات معدلات النمو اليومية خلال فترات النمو المختلفة تلاها الخلط العکسى بين ذکور (LASM) وإناث (EASM). وکانت قوة الخلط المباشرة عالية المعنوية فى معظم صفات وزن الجسم المدروسة من عمر الفقس حتى عمر 6 أسابيع ما عدا صفة وزن الجسم عند عمر 4 أسبوع وکانت قوة الخلط المباشرة عالية المعنوية فى صفات معدلات النمو اليومية خلال فترات النمو المختلفة وکانت نسبة الخلط لهذه الصفات مرتفعة فى فترتى النمو من الفقس حتى عمر 2 أسبوع ومن 2- 4 أسابيع وإنخفضت إلى  فى فترتى النمو من 4-6 أسبوع ومن الفقس - 6 أسابيع.

و بالنسبة لصفات الذبيحة : صاحب الخلط بين ذکور (EASM) وإناث (LASM) تفوق فى کل صفات الذبيحة المدروسة تلاها الخلط العکسى بين ذکور (LASM) وإناث (EASM). وکانت قوة الخلط المباشرة عالية المعنوية فى معظم صفات الذبيحة ماعدا صفتى النسبة المئوية للحم والأجزاء المأکولة من الذبيحة ولم يکن لقوة الخلط المباشرة تأثيرا معنويا عليها وکانت نسبة الخلط لهذه الصفات مرتفعة بالنسبة لصفتى النسبة المئوية للعظام ووزن الذبيحة وإنخفضت إلى  بالنسبة لصفتى النسبة المئوية للحم والنسبة المئوية للتصافى.

الکلمات الاسترشادية : الخلط, عمر النضج الجنسى المبکر والمتأخر ,السمان اليابانى