Estimation of (co)variance components, genetic parameters, and genetic trends of growth traits in community-based breeding programs of Bonga sheep.

Community-based sheep breeding programs (CBBPs) have been adopted strategically to improve Bonga sheep, the most popular sheep breed in Ethiopia. The present study was undertaken to estimate genetic parameters and genetic trends for growth traits and inbreeding levels in each Bonga sheep CBBP. Data pertaining to growth traits, spanning a period of seven years (2012-2017), were collected from 14 Bonga sheep CBBPs. Data were analyzed using the General Linear Model procedure of SAS to study the performance of the breed over the years. The genetic parameters were estimated by univariate and multivariate animal model using restricted maximum likelihood method of WOMBAT software. The genetic trends were estimated by the regression of the average breeding values of the animals on the year of birth. The overall least square means ±â€¯SE of BW (kg) were 3.10 ±â€¯0.010, 16.1 ±â€¯0.07, 24.7 ±â€¯0.20, 30.4 ±â€¯0.40 and 34.0 ±â€¯0.84 for birth weight (BWT), weaning weight (WWT), six-month weight (SMWT), nine-month weight (NMWT) and yearling weight (YWT), respectively. Direct heritability estimates from selected models were 0.56 ±â€¯0.030, 0.36 ±â€¯0.030, 0.22 ±â€¯0.040, 0.17 ±â€¯0.070 and 0.13 ±â€¯0.150 for BWT, WWT, SMWT, NMWT and YWT, respectively. Six-month weight was the selection trait and presented positive trends for 10 CBBPs, and negative trends for four CBBPs. Moderate to high heritability estimates and positive genetic trends indicated scope for further improvement of BW. Additionally, the positive and high correlation between BW traits indicated that selection for just one trait would also improve the other traits through correlated responses.

Converting multi-trait breeding objectives into operative selection indexes to ensure genetic gains in low-input sheep and goat breeding programmes.

Small ruminant breeding programmes in low-input production systems are best organised at the community level. Participant farmers have to agree on goal traits and their relative importance. When BLUP breeding values of goal traits are not available in time, appropriate selection indexes can be used to aid visual selection. Taking Ethiopian Abergelle goat and Bonga sheep community-based breeding programmes (CBBPs) as an example, breeding objective functions were defined and selection indexes were constructed and evaluated. Breeding goals for Abergelle goats included early sale weight, survival and milk production. Breeding goals for Bonga included the number of offspring born, sale weight and survival. Economic weights of objective traits can be used in several ways depending on measured traits and the reliability of their genetic parameters. Selection indexes included combinations of objective traits measured on candidates and their dams and situations when Abergelle communities prefer to restrict genetic changes in number of offspring born or adult weight and when Bonga communities prefer to restrict changes in adult weight. Genetic and economic gains were evaluated as well as sensitivity to feed cost assumptions and to repeated dam records. After independent culling on preponderant traits such as coat colour and horn/tail type, sires in Abergelle goat community breeding programmes should be selected on indexes including at least own early live weight and their dams average milk production records. Sires for Bonga sheep programmes should be selected on own early live weight and desirably also on their dam's number of offspring born. Sensitivity to feed cost assumptions was negligible but repeated measurements of dam records improved index accuracies considerably. Restricting genetic changes in number of offspring born or adult weight is not recommended.

Community-based sheep breeding programs generated substantial genetic gains and socioeconomic benefits.

Community-based breeding programs (CBBPs) for small ruminants have been suggested as alternatives to centralised, government-controlled breeding schemes which have been implemented in many developing countries. An innovative methodological framework on how to design, implement and sustain CBBPs was tested in three sites in Ethiopia: Bonga, Horro and Menz. In these CBBPs, the main selection trait identified through participatory approaches was 6-month weight in all three sites. In Horro and Bonga, where resources such as feed and water permitted larger litter sizes, twinning rate was included. Ten-year (2009 to 2018) performance data from the breeding programs were analysed using Average Information Restricted Maximum Likelihood method (AI-REML). Additionally, the socioeconomic impact of CBBPs was assessed. Results indicated that 6-month weight increased over the years in all breeds. In Bonga, the average increase was 0.21 ± 0.018 kg/year, followed by 0.18 ± 0.007 and 0.11 ± 0.003 kg/year in Horro and Menz, respectively. This was quite substantial in an on-farm situation. The birth weight of lambs did not improve over the years in Bonga and Horro sheep but significant increases occurred in Menz. Considering that there was no direct selection on birth weight in the community flock, the increased weights observed in Menz could be due to correlated responses, but this was not the case in Bonga and Horro. The genetic trend for prolificacy over the years in both Bonga and Horro flocks was positive and significant (P < 0.01). This increase in litter size, combined with the increased 6-month body weight, increased income by 20% and farm-level meat consumption from slaughter of one sheep per year to three. The results show that CBBPs are technically feasible, result in measurable genetic gains in performance traits and impact the livelihoods of farmers.

QTL associated with Fusarium head blight resistance in the soft red winter wheat Ernie.

Fusarium head blight (FHB), mainly caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schw. (Petch)], is an increasingly important disease of wheat (Triticum aestivum L.). Host-plant resistance provides the best hope for reducing economic losses associated with FHB, but new sources of resistance are limited. The moderately resistant winter wheat cultivar, Ernie, may provide a source of resistance that differs from Sumai 3 but these genes have not been mapped. Also hindering resistance breeding may be associations of resistance with agronomic traits such as late maturity that may be undesirable in some production environments. This research was conducted to identify QTL associated with type II FHB resistance (FHB severity, FHBS), and to determine if they are associated with days to anthesis (DTA), number of spikelets (NOS), and the presence/absence of awns. Two hundred and forty-three F(8) recombinant inbred lines from a cross between the resistant cultivar, Ernie and susceptible parent, MO 94-317 were phenotyped for type II FHB resistance using point inoculation in the greenhouse during 2002 and 2003. Genetic linkage maps were constructed using 94 simple sequence repeat (SSR) and 146 amplified fragment length polymorphic (AFLP) markers. Over years four QTL regions on chromosomes 2B, 3B, 4BL and 5A were consistently associated with FHB resistance. These QTL explained 43.3% of the phenotypic variation in FHBS. Major QTL conditioning DTA and NOS were identified on chromosome 2D. Neither the QTL associated with DTA and NOS nor the presence/absence of awns were associated with FHB resistance in Ernie. Our results suggest that the FHB resistance in Ernie appears to differ from that in Sumai 3, thus pyramiding the QTL in Ernie with those from Sumai 3 could result in enhanced levels of FHB resistance in wheat.

Inheritance of Fusarium head blight resistance in the soft red winter wheat Ernie.

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [telomorph:Gibberella zeae Schw. (Petch)], is an increasingly important disease of wheat (Triticum aestivum L.). Host-plant resistance is considered to be the most economical means of control, but a lack of unique sources of resistance has hindered efforts to breed resistant varieties. The soft red winter wheat, Ernie, has moderately high FHB resistance and is widely used in U.S. breeding programs; however, the genetics of resistance have not been studied. The objectives of this study were to estimate the genetic effects, gene numbers, and heritability for traits related to FHB resistance in Ernie through generation means analyses and variance analyses of 243 F3-derived F8 and F9 recombinant inbred lines (RILs). Replicated experiments were grown in the greenhouse, inoculated with F. graminearum, and evaluated for disease spread and the FHB index (FHBI). The latter was calculated as the percentage of diseased spikelets in inoculated spikes and is often referred to as type-II resistance. Gene action for both disease spread and FHBI was primarily additive with partial dominance for low disease. Broad-sense heritabilities for spread and FHBI were 78.2% and 78.3%, respectively, while the narrow-sense heritabilities were 51.3% and 55.4%, respectively. Line-mean heritabilities from analyses of variance of RILs were 0.70 and 0.87 for spread and FHBI, respectively. A minimum of four genes conditioned both disease spread and FHBI. These results suggest that breeders should be able to enhance FHB resistance by combining the resistance in Ernie with other complementary additive sources of resistance.