Genetic analysis of reproductive characteristics in Iran-Black sheep

Baneh, Hasan; Ahmadpanah, Javad; Mohammadi, Yahya

doi:10.4025/actascianimsci.v42i1.47380

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ANIMAL PRODUCTION • Acta Sci., Anim. Sci. 42 • 2020 • https://doi.org/10.4025/actascianimsci.v42i1.47380 copy

Genetic analysis of reproductive characteristics in Iran-Black sheep

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT.

This study was conducted to estimate genetic parameters and trends for reproduction traits using data collected at the breeding station of Iran-Black sheep during 1980 to 2004. The traits included in the analyses were litter size at birth (LSB) and weaning (LSW) and litter mean weight per lamb born (LMWLB) and weaned (LMWLW) as basic traits, and total litter weight at birth (TLWB) and weaning (TLWW) as composite traits. Direct heritability estimates for LSB, TLWB, LMWLB, LSW, TLWW and LMWLW were 0.11, 0.07, 0.33, 0.08, 0.09 and 0.11, respectively. The permanent environmental effects had significant impact on all traits and ranged from 0.05 to 0.16. Effect of service sire was highly significant (p < 0.01) for all traits except LMWLW. Estimates of genetic correlations ranged from -0.76 (LSB-LMWLB) to 0.98 (LSB-LSW). Phenotypic and environmental correlations were generally lower than those of genetic correlations. Environmental correlations ranged from -0.55 (LSW-LMWLW) to 0.99 (LSB-LSW). Also, the estimated correlation for the effect of service sire ranged from -0.77 (LMWLB-TLWW) to 0.96 (LSB-LSW and LSB-TLWW). The results suggest that selection based on TLWB could be more effective than the other traits to enhance reproductive performance in Iran-Black ewes.

Keywords:
Iran-Black sheep; reproduction traits; REML

Trait1	Model	^bσ² _a	σ² _Pe	σ² _S	σ² _e	σ² _p	h ² _a	Pe ²	S ²	r	-2LogL	Sig.
LSB^a	1	0.0573			0.3270	0.3843	0.15			0.15	107.356
	2	0.0410	0.0193		0.3200	0.3803	0.11	0.05		0.16	103.468
	3	0.0566		0.0048	0.3237	0.3851	0.15		0.01	0.15	103.056
	4	0.0404	0.0193	0.0048	0.3166	0.3811	0.11	0.05	0.01	0.16	99.108	p < 0.01
LSW	1	0.0389			0.3031	0.3419	0.11			0.11	-153.559
	2	0.0272	0.0162		0.2960	0.3395	0.08	0.05		0.13	-157.391
	3	0.0383		0.0037	0.3006	0.3425	0.11		0.01	0.11	-156.478
	4	0.0268	0.0163	0.0037	0.2934	0.3402	0.08	0.05	0.01	0.13	-160.384	p < 0.01
LMWLB	1	0.2925			0.4312	0.7238	0.40			0.40	1355.40
	2	0.2335	0.0409		0.4263	0.7007	0.33	0.06		0.39	1352.51
	3	0.2906		0.0049	0.4280	0.7235	0.40		0.01	0.40	1352.94
	4	0.2342	0.0392	0.0046	0.4234	0.7014	0.33	0.06	0.01	0.39	1350.25	p < 0.05
LMWLW	1	6.9361			17.1487	24.0847	0.29			0.29	11217.46
	2	2.5931	3.6286		16.4703	22.6921	0.11	0.16		0.27	11197.70	p < 0.01
	3	6.9303		0.0360	17.1219	24.0882	0.29		0.00	0.29	11217.36
	4	2.5935	3.6246	0.0290	16.4490	22.6962	0.11	0.16	0.00	0.27	11197.63
TLWB	1	0.4755			3.1206	3.5961	0.13			0.13	6342.83
	2	0.2415	0.2802		3.0170	3.5388	0.07	0.08		0.15	6333.47
	3	0.4627		0.0729	3.0744	3.6100	0.13		0.02	0.13	6334.34
	4	0.2406	0.2712	0.0713	2.9724	3.5554	0.07	0.08	0.02	0.14	6325.25	p < 0.01
TLWW	1	18.2302			125.0106	143.2408	0.13			0.13	16360.72
	2	13.0583	6.5471		122.4480	142.0534	0.09	0.05		0.14	16357.37
	3	18.1405		1.7112	123.7410	143.5928	0.13		0.01	0.13	16356.69
	4	12.8638	6.7406	1.7393	121.0595	142.4032	0.09	0.05	0.01	0.14	16353.10	p < 0.01

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[1] * Author for correspondence. E-mail: Mohamadi_yahya@yahoo.com

Trait	LSB^a	LSW	LMWLB (kg)	LMWLW(kg)	TLWB (kg)	TLWW (kg)
Animal in pedigree	1239	1202	1239	1202	1239	1202
No. records	2806	2827	2806	2827	2806	2827
No. sires	72	72	72	72	72	72
No. dams	612	613	612	613	612	613
No. service sires	92	98	92	98	92	98
Mean	1.57	1.48	3.88	23.94	5.86	34.33
S.D	0.63	0.59	0.83	5.11	1.98	12.68
Min	1	1	1.65	8.36	1.81	8.36
Max	5	4	6.7	43.63	16.42	110.89

	LSB^a	LSW	LMWLB (kg)	LMWLW (kg)	TLWB (kg)	TLWW (kg)
Lambing Year	**^b	**	**	**	**	**
Lambing Season	ns	ns	Ns	ns	ns	ns
Ewe age	**	**	**	ns	**	**
2	1.36±0.06b	1.37±0.07c	3.91±0.08b	24.35±0.59	5.13±0.19c	33.05±1.47c
3	1.58±0.06a	1.58±0.07b	4.09±0.08a	24.85±0.59	6.22±0.19b	38.48±1.49b
4	1.63±0.06a	1.63±0.07ab	4.11±0.08a	24.87±0.58	6.47±0.20a	39.90±1.46a
5	1.64±0.07a	1.70±0.08a	4.15±0.09a	24.55±0.63	6.61±0.21a	41.20±1.57a
6	1.63±0.07a	1.62±0.08ab	4.20±0.10a	24.58±0.67	6.61±0.23a	39.58±1.67ab
7	1.54±0.08a	1.55±0.09b	4.19±0.11a	24.05±0.73	6.23±0.26ab	37.25±1.83b

Trait 1	Trait 2	r_g	r_pe	r_s	r_e	r_p
LSB	LSW	0.98	0.99	0.96	0.80	0.83
LSB	TLWB	0.43	0.83	0.95	0.86	0.83
LSB	TLWW	0.67	0.63	0.96	0.01	0.67
LSB	LMWLB	-0.76	-0.13	-0.29	-0.50	-0.47
LSB	LMWLW	-0.49	-0.57	-	-0.40	-0.38
LSW	TLWB	0.74	0.76	0.85	0.74	0.72
LSW	TLWW	0.82	0.57	0.95	0.89	0.85
LSW	LMWLB	-0.60	-0.23	-0.61	-0.42	-0.39
LSW	LMWLW	-0.34	-0.58	-	-0.42	-0.37
LMWLB	LMWLW	0.89	0.95	-	0.48	0.54
LMWLB	TLWB	0.32	0.31	-0.09	-0.07	0.05
LMWLB	TLWW	-0.08	0.66	-0.77	-0.25	-0.13
LMWLW	TLWB	0.32	0.13	-	-0.25	-0.13
LMWLW	TLWW	0.28	0.33	-	-0.01	0.14
TLWB	TLWW	0.92	0.88	0.95	0.68	0.71

Trait	GT±S.E.^b	p value	GP
LSB^a (No.)	0.010±0.001	<0.0001	0.192
LSW (No.)	0.010±0.001	<0.0001	0.177
TLWB (g)	0.027±0.002	<0.0001	0.567
TLWW (g)	-0.004±0.002	0.09	-0.067
LMWLB (g)	0.188±0.019	<0.0001	3.440
LMWLW (g)	-0.005±0.007	0.5	-0.198