Genetic and phenotypic parameters for growth and lamb survival traits of Farta and their crosses with Washera sheep in northwest Ethiopia: Inputs to design of breeding programs

Figures & data

Table 1. Number of records, mean (± standard deviation) and coefficient of variation for traits

Studied traits	No. records	Mean ± SD^1	CV (%)^2
Birth weight (kg)	3996	3.15 ± 0.67	21.23
Weaning weight (kg)	3128	12.35 ± 2.57	20.82
Pre-weaning daily gain (kg)	2843	0.10 ± 0.03	27.59
Six-month weight (kg)	2568	16.68 ± 2.94	17.65
Yearling weight (kg)	1074	22.42 ± 3.89	17.35
Pre-weaning lamb survival (%)	4318	91.41 ± 28.03	30.66

¹SD = standard deviation; ²CV = coefficient of variation

Table 2. Least square means of the studied traits adjusted for various fixed effects

	Traits with least square mean for the different fixed effects^2
Model factors^1	BWT	WWT	PWDG	SMWT	YWT	PWLS
Sex of lamb	***	***	NS	***	NS	NS
Male	3.19^a	11.93^a	0.095	16.63^a	22.42	0.87
Female	3.06^b	11.59^b	0.094	16.28^b	22.45	0.89
Birth type	***	***	***	***	NS	***
Single	3.23^a	12.14^a	0.098^a	16.90^a	22.60	0.90^a
Twins	3.02^b	11.38^b	0.091^b	16.00^b	22.28	0.86^b
Birth season	NS	NS	NS	**	*	***
1	3.03	11.23	0.092	15.86^a	21.74^a	0.90^a
2	3.22	11.77	0.097	17.05^b	23.14^b	0.87^b
Dam parity	***	NS	NS	NS	NS	NS
1	3.03^a	11.58	0.094	16.63	22.75	0.87
2	3.12^b	11.80	0.095	16.51	22.70	0.88
3	3.16^bc	11.81	0.094	16.36	22.30	0.88
4	3.14^bc	11.83	0.095	16.29	22.00	0.89
≥5	3.17^c	11.79	0.094	16.49	22.63	0.90
Birth year	***	***	***	***	***	***
2015	3.84^a	14.56^a	0.120^a	18.93^a	25.40^a	0.93^ab
2016	3.00^b	11.27^b	0.090^b	16.38^ab	22.58^b	0.92^a
2017	2.94^b	10.92^bc	0.087^bc	15.51c	21.04^c	0.89^bd
2018	3.01^b	10.65^c	0.084^c	15.80^c	21.40^cd	0.84^c
2019	2.93^b	11.51^b	0.091^bc	15.78^bc	22.60^bd	0.87^cd
2020	2.69^c	12.90^a	0.113^a	15.63^bc	19.63^c	0.84^c
Flock (19 levels)	***	***	***	***	***	***
Birth type X Birth year	NS	***	***	***	NS	NS
Birth season X Birth year	***	***	***	***	**	NS
Birth year X Flock	***	***	***	***	**	NS
Birth season X Flock	***	***	***	***	***	NS

¹Least square means of a particular fixed effect represented with different letters in the same column are statistically significant; NS = non-significant (P > 0.05), * = P < 0.05, ** = P < 0.01, *** = P < 0.001

²BWT = birth weight (kg), WWT = weaning weight (kg), PWDG = Pre-weaning daily gain (kg), SMWT = six-month weight (kg), YWT = yearling weight (kg), PWLS = pre-weaning lamb survival (number of lambs alive at weaning divided by the total number of lambs born).

Table 3. Fixed effects included in the genetic analysis model for the studied traits

Fixed effects^1	Traits^2
	BWT	WWT	PWDG	SMWT	YWT	PWLS
Sex of lamb	X	X	-	X	-	-
Birth type	X	X	X	X	X	X
Birth season	X	X	X	X	X	X
Dam parity	X	-	-	-	-	-
Birth year	X	X	X	X	X	X
Flock	X	X	X	X	X	X
Birth type X birth year	-	X	X	X	-	-
Birth season X birth year	X	X	X	X	X	-
Flock X birth year	X	X	X	X	X	-
Flock X birth season	X	X	X	X	X	-

¹Fixed effects represented with X in the same column were included in the genetic analysis model for each trait, whereas those with a hyphen (-) were not included because their effects were not statistically significant. The number of classes for each fixed effect is available in Table 2.

²see, Table 2 for traits abbreviations

Table 4. Variance components, heritability estimates and log-likelihood values of traits

Traits^1	Model^2	Variance components and heritability estimates^3							LL^4
		${\sigma }_a^2$	${\sigma }_m^2$	${\sigma }_{PE}^2$	${\sigma }_e^2$	${\sigma }_P^2$	$h_a^2$+ SE	$h_m^2$+ SE
BWT	1	0.043	-	-	0.146	0.189	0.23 ± 0.05	-	1178
	2	0.015	-	0.093	0.078	0.186	0.08 ± 0.03	-	1234
	3	0.013	0.089	-	0.084	0.186	0.07 ± 0.03	0.48 ± 0.04	1227
	4	0.015	n/a^5	0.093	0.078	0.186	0.08 ± 0.03	n/a	1234
WWT	1	1.453	-	-	2.582	4.034	0.36 ± 0.07	-	−3689
	2	0.801	-	1.121	2.012	3.935	0.20 ± 0.05	-	−3674
	3	0.776	1.139	-	2.018	3.933	0.20 ± 0.05	0.29 ± 0.05	−3673
	4	0.775	1.139	n/a	2.017	3.931	0.20 ± 0.05	0.29 ± 0.05	−3673
PWDG	1	0.135	-	-	0.347	0.482	0.28 ± 0.07	-	−9919
	2	0.075	-	0.144	0.255	0.475	0.16 ± 0.05	-	−9904
	3	0.072	0.148	-	0.255	0.475	0.15 ± 0.05	0.31 ± 0.05	−9903
	4	0.072	0.148	n/a	0.254	0.474	0.15 ± 0.05	0.31 ± 0.05	−9903
SMWT	1	3.650	-	-	2.203	5.853	0.62 ± 0.10	-	−3414
	2	1.377	-	2.145	1.915	5.437	0.25 ± 0.07	-	−3390
	3	1.300	2.189	-	1.942	5.431	0.24 ± 0.06	0.40 ± 0.05	−3389
	4	1.298	2.189	n/a	1.942	5.429	0.24 ± 0.06	0.40 ± 0.05	−3389
YWT	1	6.114	-	-	3.688	9.802	0.62 ± 0.15	-	−1674
	2	2.805	-	5.040	1.521	9.366	0.30 ± 0.14	-	−1660
	3	2.612	5.073	-	1.667	9.352	0.28 ± 0.13	0.54 ± 0.10	−1660
	4	2.755	1.363	3.697	1.547	9.361	0.29 ± 0.14	0.15 ± 0.57	−1660
PWLS	1	0.022	-	-	0.055	0.077	0.29 ± 0.05	-	3378
	2	0.010	-	0.029	0.036	0.075	0.14 ± 0.04	-	3425
	3	0.010	0.028	-	0.037	0.075	0.13 ± 0.03	0.38 ± 0.04	3422
	4	0.010	0.001	0.028	0.036	0.075	0.14 ± 0.04	0.02 ± 0.15	3425
	Logit	0.821	0.037	n/a	3.29	4.148	0.20 ± 0.07	0.01 ± 0.07	-

¹See, Table 2 for traits abbreviations

²Model 1 = direct additive animal genetic; model 2 = model 1 + permanent environment effect; model 3 = model 1 + maternal genetic effect; model 4 = contains all the three random effects

³Variances for additive genetic (${\sigma }_a^2$), maternal (${\sigma }_m^2$), permanent environmental (${\sigma }_{PE}^2$), residual (${\sigma }_e^2$) and phenotypic (${\sigma }_P^2$); Heritability of direct animal ($h_a^2$) and maternal ($h_m^2$) with standard error (SE).

⁴Bold log-likelihood (LL) values in the last column indicate the best-fitted models for each trait.

⁵n/a = not applicable when parameters were not estimable.

Table 5. Genetic (above) and phenotypic (below) correlations estimated for the different traits

Traits^1	BWT	WWT	PWDG	SMWT	YWT	PWLS
BWT		0.15 ± 0.24^#	0.48 ± 0.11	0.17 ± 0.23	0.60 ± 0.27	−0.36 ± 0.22
WWT	0.24 ± 0.02		0.98 ± 0.01	0.64 ± 0.13	0.33 ± 0.22	0.46 ± 0.10
PWDG	0.44 ± 0.02	0.97 ± 0.00		0.70 ± 0.13	0.28 ± 0.24	0.26 ± 0.15
SMWT	0.16 ± 0.02	0.52 ± 0.02	0.48 ± 0.02		0.77 ± 0.12	0.50 ± 0.14
YWT	0.26 ± 0.03	0.27 ± 0.03	0.21 ± 0.04	0.76 ± 0.01		0.10 ± 0.16
PWLS	0.03 ± 0.02	0.15 ± 0.02	0.38 ± 0.01	0.34 ± 0.02	0.14 ± 0.02

¹See, Table 2 for traits abbreviations.

^#Values in the parentheses are standard errors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, ASA, upon reasonable request.