Impacts of Community‐Based Breeding Programs on Growth and Reproductive Performance of Ethiopian Sheep Breeds: A Meta‐Analysis

ObjectiveThe objectives of the study were to evaluate reproductive performance and selection response through genetic trend of community-based breeding programs (CBBPs) of Bonga sheep.MethodsReproduction traits data were collected between 2012 and 2018 from Bonga sheep CBBPs. Phenotypic performance was analyzed using the general linear model procedures of Statistical Analysis System. Genetic parameters were estimated by univariate animal model for age at first lambing (AFL) and repeatability models for lambing interval (LI), litter size (LS), and annual reproductive rate (ARR) traits using restricted maximum likelihood method of WOMBAT. For correlations bivariate animal model was used. Best model was chosen based on likelihood ratio test. The genetic trends were estimated by the weighted regression of the average breeding value of the animals on the year of birth/lambing.ResultsThe overall least squares mean±standard error of AFL, LI, LS, and ARR were 375± 12.5, 284±9.9, 1.45±0.010, and 2.31±0.050, respectively. Direct heritability estimates for AFL, LI, LS, and ARR were 0.07±0.190, 0.06±0.120, 0.18±0.070, and 0.25±0.203, respectively. The low heritability for both AFL and LI showed that these traits respond little to selection programs but rather highly depend on animal management options. The annual genetic gains were −0.0281 days, −0.016 days, −0.0002 lambs and 0.0003 lambs for AFL, LI, LS, and ARR, respectively.ConclusionImplications of the result to future improvement programs were improving management of animals, conservation of prolific flocks and out scaling the CBBP to get better results.

Investigation was carried out to assess the effects of environmental factors and to estimate genetic parameters and trends for reproductive traits in Bonga sheep, Ethiopia. Animals used in this study were managed by two communities involved in a community-based breeding programs (CBBPs) from 2009 to 2018. The database consisted of 15,595 individual phenotypic information from about 1500 ewes with variable number of records for each trait. The traits analyzed were age at first lambing (AFL), lambing interval (LI), and litter size (LS). Fixed effect analysis was done using the general linear model procedures of SAS. The Average Information Restricted Maximum Likelihood method of WOMBAT, fitting univariate animalmodel, was used to estimate heritabilities, repeatabilities and breeding values. Results showed that Bonga sheep had overall mean AFL, LI, and LS of 453 ± 109days, 254 ± 51days, and 1.43 ± 0.008, respectively. All traits were influenced (p < 0.01) by lambing year, lambing season, breeder communities, and parity of ewes. Estimates of heritability for AFL, LI, and LS were 0.015 ± 0.143, 0.009 ± 0.070, and 0.085 ± 0.110, respectively. The low heritabilities for the traits are expected and indicate low possibility of achieving rapid genetic progress through phenotypic selection. The repeatability estimates for LI and LS were low (0.109 and 0.196, respectively) indicating that non-genetic factors had significant influence to the variation in these traits among parities; therefore, selection decision on ewes should consider repeated records. The genetic trend for AFL, LI, and LS over the years was significant (p < 0.01). Positive values for LS and negative for AFL and LI were recorded, implying that the well-structured CBBPs have resulted in measurable genetic gains for the reproductive traits.

ABSTRACTThe evaluation of breeding schemes against established objectives and selection traits is essential for assessing the performance, outputs, and overall impacts of breeding programmes. In Ethiopia, most Community‐Based Breeding Programmes (CBBPs) have prioritised growth traits, particularly live weight, as the main selection criteria. However, since productivity relies on both reproductive and growth traits, it is critical to evaluate how these traits are evolving to make necessary adjustments in management practices and breeding schemes. This study considered five indigenous sheep breeds (Menz, Semein, Horro, Bonga and Doyogena), managed under CBBPs since 2009. Fixed effects for reproductive traits were estimated using the GLM procedures of SAS 9.4. Genetic parameters were estimated for all traits using the restricted maximum likelihood (REML) method with WOMBAT software, employing a multivariate repeated model, except for age at first lambing (AFL), which was analysed using a non‐repeated multivariate model. Significant effects (p < 0.001) were observed for year of birth, breed of ewe, parity and birth season across all traits in the breeds studied. A general trend of improvement in litter size at birth (LSB), total litter weight at birth (TLWB), litter size at weaning (LSW), total litter weight at weaning (TLWW) and annual reproductive rate (ARR) was noted with increasing ewe parity until the seventh parity, followed by a decline thereafter. Direct heritability estimates for the traits according to the ewe breeds ranged from 0.03 to 0.25 for LSB, 0.02 to 0.16 for LSW, 0.08 to 0.21 for TLWB, 0.07 to 0.22 for TLWW, 0.03 to 0.19 for LI, 0.08 to 0.32 for ARR and 0.15 to 0.36 for AFL. Estimates of direct heritability and repeatability varied by breed and location, generally falling within small to medium ranges. Moderate to high genetic correlations were found between TLWW and other traits suggesting that selection for TLWW may significantly influence reproductive performances across most sheep breeds, with the exception of Menz sheep. The variations in genetic estimates across different breeds and locations indicate that genetic influences may vary depending on the specific context. Moderate to high genetic correlations between TLWW and other reproductive traits suggest that prioritising selection for TLWW could have a significant positive impact on reproductive performance across most sheep breeds, though the Menz breed may not exhibit the same expected benefits. These findings emphasise the need to integrate genetic selection with effective management practices tailored to each breed's specific needs, recommending the culling of unproductive ewes after the seventh parity to enhance the sustainability and productivity of CBBPs in Ethiopia.

ABSTRACTThe objective of this study was to determine the effect of some environmental factors on reproductive and productive performance traits and to estimate their repeatability in Pelibuey ewes in Yucatan, Mexico. Information of 956 Pelibuey ewes lambing from 2007 to 2013 in three farms were used (n = 2215 lambing). The assessed traits were age at first lambing (AFL), lambing interval (LI), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB) and litter weight at weaning adjusted to 60 days (LWWA). Mixed models were used to determine the effects of farm, lambing season or birth, year of lambing or birth and parity number on above traits. Repeatability were calculated using the between and within ewe components of variance. Overall means and standard deviations for AFL, LI, LSB, LWB, LSW and LWWA were 526.7 ± 107.1d, 259.4 ± 70.3d, 1.5 ± 0.6, 4.3 ± 1.6 kg, 1.4 ± 0.7 and 19.1 ± 10.1 kg, respectively. Repeatability for LI, LSB, LSW, LWB and LWWA were 0.06 ± 0.20, 0.12 ± 0.04, 0.00 ± 0.04, 0.13 ± 0.04 and 0.01 ± 0.04, respectively. AFL was not affected by any of the environmental factors. However, the other traits were influenced (p < .05) by farm, lambing year, lambing season, parity and LSB (for LI and LSW). In conclusion, productive and reproductive performance traits of Pelibuey ewes were influenced by environmental factors, and repeatability were lows. To improve the performance of Pelibuey ewes adjustments to management schemes should be made as well as to base the selection on more than one productive and reproductive indicator.

The genetic parameters for growth, reproductive and maternal traits in a multibreed meat sheep population were estimated by applying the Average Information Restricted Maximum Likelihood method to an animal model. Data from a flock supported by the Programa de Melhoramento Genético de Caprinos e Ovinos de Corte (GENECOC) were used. The traits studied included birth weight (BW), weaning weight (WW), slaughter weight (SW), yearling weight (YW), weight gain from birth to weaning (GBW), weight gain from weaning to slaughter (GWS), weight gain from weaning to yearling (GWY), age at first lambing (AFL), lambing interval (LI), gestation length (GL), lambing date (LD - number of days between the start of breeding season and lambing), litter weight at birth (LWB) and litter weight at weaning (LWW). The direct heritabilities were 0.35, 0.81, 0.65, 0.49, 0.20, 0.15 and 0.39 for BW, WW, SW, YW, GBW, GWS and GWY, respectively, and 0.04, 0.06, 0.10, 0.05, 0.15 and 0.11 for AFL, LI, GL, LD, LWB and LWW, respectively. Positive genetic correlations were observed among body weights. In contrast, there was a negative genetic correlation between GBW and GWS (-0.49) and GBW and GWY (-0.56). Positive genetic correlations were observed between AFL and LI, LI and GL, and LWB and LWW. These results indicate a strong maternal influence in this herd and the presence of sufficient genetic variation to allow mass selection for growth traits. Additive effects were of little importance for reproductive traits, and other strategies are necessary to improve the performance of these animals.

Reproductive traits are of paramountimportance in an efficient lamb production system. In Croatia, values of reproductive traits of Romanov sheep are below the average expected for this breed, indicating the need for improvement of these traits to exploit the breed’s full reproductive potential. This study was conducted on 260 Romanov ewes located at a commercial Romanov sheep farm in Croatia. All ewes were kept under similar conditions, and reproductive management was based on accelerated lambing with continuous mating. Linear models with fixed effects were used to estimate the influence of year of birth/lambing, season of birth/lambing, ram, parity and litter type on litter size (LS), age at first lambing (AFL) and lambing interval (LI). Average LS was 2.11 ± 0.71, while the year of lambing and parity were the most important factors affecting this trait. The smallest litters were recorded after 1st parity (1.77 ± 0.06), and the largest after 5th parity (2.21 ± 0.08). AFL averaged 388.5 ± 72.4 days. All investigated non-genetic factors had a significant (P&amp;lt;0.05) influence on AFL, with year of birth as most important. The average LI was 241.2 ± 70.8 days. A significant (P&amp;lt;0.05) influence of all factors on LI was observed. Ewes lambing in spring (200.2 ± 7.9 days) or summer (190.5 ±6.6 days) had a significantly (P&amp;lt;0.05) shorter LI than ewes lambing in autumn (227.7 ± 8.3 days) or winter (237.2 ± 6.7 days). The longest LI was observed after the first parity (284.0 ±5.5 days). Average values for reproductive traits in the examined population of Romanov sheep were higher than those reported in the official Croatian database for breeding sheep. Non-genetic factors have a significant influence on the variation of reproductive traits of Romanov sheep, and therefore should be considered when assessing ewes’ reproductive performance.

Genetic analysis of female reproductive efficiency, scrotal circumference and growth traits in Nelore cattle

This study aims to estimate genetic parameters and genetic trends for early growth and reproductive traits of Doyogena sheep. Data used in the study were collected over 6 years (2013–2018). Studied traits were birth weight (BWT), weaning weight (WWT), 6-month weight (SMWT), average daily gains from birth to weaning (ADG0-3), average daily gains from weaning to 6-month age (ADG3-6), average daily gain from birth to 6-month age (ADG0-6), litter size (LS), lambing interval (LI), age at first lambing (AFL), and annual reproductive rate (ARR). (Co) variance components and genetic parameters were estimated using restricted maximum likelihood (REML). The analyses were carried out using WOMBAT program. Univariate analysis was applied to estimate genetic parameters. Six different animal models were fitted by including or excluding maternal effects. The direct heritability estimates for BWT, WWT, SMWT, ADG0-3, ADG3-6 and ADG0-6 were 0.33 ± 0.06, 0.31 ± 0.06, 0.14 ± 0.06, 0.13 ± 0.04, 0.11 ± 0.07, and 0.02 ± 0.05 respectively. Direct heritability for LS, LI, and AFL were 0.28 ± 0.12, 0.20 ± 0.5, and 0.001 ± 0.3, respectively. The maternal heritability estimates for BWT, WWT, and LS were 0.24 ± 0.12, 0.60 ± 0.07, and 0.24 ± 0.08, respectively. The genetic correlation between BWT with WWT and BWT with SMWT were 0.21 ± 0.07 and 0.21 ± 0.09, respectively. Genetic progress for most of the studied traits has shown promising improvements. Thus, continuation of selection, therefore, suggested for more improvements in the performance of Doyogena sheep. Direct heritability estimates decrease as lamb age increases and selection based on earlier body weight will be more efficient.

Evaluating reproduction traits in a crossbreeding program between indigenous and exotic sheep in semi-arid lands

In central Ethiopia region, the community‐based breeding program (CBBP) for improving Doyogena sheep has utilized growth traits as a primary selection criterion since its establishment. Growth, reproduction, and survival traits play a vital role in the overall productivity, so it is critical to evaluate how these traits changing overtime. This study purposed to examine variance components, genetic parameters for growth, reproductive, and survival traits, and correlations between growth and other economically important traits in Doyogena CBBPs. The data was gathered over 10 years (2013–2022) and traits considered were birth weight (BWT), weaning weight (WWT), weight at 6 months (SMW), annual reproductive rate (ARR), lambing interval (LI), litter weight at birth (LWB), litter size at birth (LSB), litter weight at weaning (LWW), litter size at weaning (LSW), ewe postpartum weight (EPPW), preweaning lamb survival (PWLS), and lamb survival up to 6 months (LSSM). Using a restricted maximum likelihood procedure, WOMBAT software was used to analyze the traits in a multitrait animal model. The values for additive heritability estimates for BWT, WWT, SMW, LSB, LWB, LSW, LWW, LI, ARR EPPW, PWLS, and LSSM were 0.37, 0.26, 0.21, 0.10, 0.24, 0.03, 0.22, 0.15, 0.12, 0.14, 0.10, and 0.08, respectively. The majority of performance traits show positive and significant (p &lt; 0.001) annual genetic trends in breeder cooperatives, indicating the feasibility of breed improvement programs. Positive and low to moderate genetic correlations were observed between growth (WWT and SMW) with most of the reproduction and lamb survival traits. The medium heritability and the moderate correlations between growth and litter weight traits (LWB and LWW) suggest the importance of considering litter weight in addition to growth traits in selection processes. In conclusion, optimizing the Doyogena sheep breeding program and improving management conditions are recommended to achieve the best outcomes and ensure long‐term sustainability.

The study was conducted in Sidama Zone, Dara District Southern Ethiopia. The intention was to investigate the effect of non-genetic factors on reproductive and growth performance of Abera sheep in the District. For this study three years (2013-2015) performance data were obtained from Hawassa research center, Dara sub-site. Study identified age at first lambing (AFL) and lambing interval (LI) of the sheep were 9.6 and 12.9 months, respectively; while annual reproductive rate and litter size of the ewes were 1.9 and 1.5 heads. Average birth weight, weaning weight and 6 month weight of Abera sheep were 2.8, 12.3 and 18.5 kg, respectively; while pre and post weaning average daily weight gains were 106 and 40 g/day, respectively. Birth type, sex and year had significant (p<0.05) effect on birth weight (BWT), weaning weight (WWT) and six-months weight; whereas season and parity had significant (P<0.05) effect on BWT and WWT only. Sex and birth type had significant (p<0.01) effect on pre-weaning average daily gain whereas year, season and parity had significant effect on both pre and post-weaning average daily gain. There was within breed variability in growth traits, which were significantly influenced by non-genetic factors like birth type, sex, year, season and parity. Selection for further improvement to achieve higher lamb crop with superior growth performance should be prioritized as within population variability is raw material for improvement through selection. Molecular characterization should also be carried out to identify uniqueness of Abera sheep.

Estimates of genetic parameters and genetic trends for growth, reproduction, milk production and milk composition traits of Awassi sheep

Effects of strategic helminthosis control on age at first lambing and lambing interval of communally grazed Menz ewes in Ethiopia

Data on growth, reproduction and wool traits of 1603 Harnali sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar over a period of 22 years (1992-2013) were utilized for genetic analysis. The overall least squares mean for birth weight (BW), weaning weight (WW), six month body weight (SMW), age at first lambing (AFL), weight at lambing (WL), average lambing interval (ALI), greasy fleece weight (GFW), staple length (SL) and Fibre diameter (FD) were estimated as 3.35±0.02 kg, 12.41±0.08 kg, 16.30±0.12 kg, 707.05±2.07 days, 26.91±0.10 kg and 402.85±2.40 days, 1.62±0.02 kg, 5.65±0.03 cm and 25.85±0.07 μ, respectively. The effect of year of birth, sex of lamb and dam's weight at lambing were significant for all growth traits. The effect of year of birth and dam's weight at lambing were significant for all reproduction traits and GFW. No definite trend was observed over the years for body weights and reproductive traits. The effect of sex was significant for early growth traits. The heritability estimates were moderate for all the growth traits with high genetic correlations of BW and WW with SMW. Reproduction traits had lower estimates of heritability which indicated presence of lower additive genetic variance for these traits. Heritability estimates for studied wool traits were moderate to high. Positive genetic and phenotypic correlation of BW and WW with six month body weight and grease fleece weight indicated that selection for six month body weight would increase body weight and grease fleece weight.

The study was conducted in North- Western zone of Tigray region, in Humera District Northern part of Ethiopia; with the objective of to measure reproductive performances of “Begayt” sheep under farmers and ranch management conditions. The data on reproductive performance of Begayt sheep (n=150) kept at three different sheep farms in Western Zone of Tigray, Quafta Humera district, Government Ranch (GovR) (n=50), Privet Ranch (PrivR) (n=50) and Privet Farm (PrivF) (n=50), under semi-intensive management system, were analyzed. General linear model was used for analyzing the data. The fixed effects in the model included location of flock, age, type of birth, sex of lamb and their interactions. The overall findings of reproductive traits such as fertility, prolificacy, single lambing, twinning rate, lambs born alive and sex ratio (male: female) were 92.67, 101.33, 89.86, 10.14, 96.33% and 50.33:49.67, respectively. The highest value for twinning rate was recorded in GovR (13.04%) and the lowest in PrivF (6.52%). All traits were significantly different (P 0.05) between flocks. The overall results revealed that age of dam, age at first service (AFS), service period (SP), age at first lambing (AFL) and lambing interval (LI) were 1078±2.2, 579.61±0.6, 206.25±0.2, and 731.67±0.3 and 256.60±0.3 days, respectively. The results of ANOVA showed that locations had significant effect (P<0.05) on AFS and SP; however lambing interval and age at first lambing were not affected. Age of ewe, type of birth, sex of lamb(s) born and interaction between these factors did not influence the traits significantly. It was concluded that reproductive performance of Begayt sheep was modest so it is vital to improve management, nutritional and breeding practices at the farm.