Dissertations

Phenotypic characterization of indigenous chickens and evaluation of Enteromorpha prolifera polysaccharide supplementation on growth performance and anticoccidial efficacy

2026-09-04T07:05:18Z

Phenotypic characterization of indigenous chickens and evaluation of Enteromorpha prolifera polysaccharide supplementation on growth performance and anticoccidial efficacy Muluneh, Bekalu Investigating chicken production systems, along with the ecotype's productive and morphological traits, as well as the challenges and opportunities in chicken production is crucial for developing sustainable breeding programs. The aim of the dissertation was to phenotypically characterize the indigenous chicken ecotypes and evaluate the effect of Enteromorpha prolifera polysaccharide on growth performance and anticoccidial efficacy. The dissertation is based on four manuscripts mentioned as chapters (Chapter 4 - Chapter 7). The first manuscript (Chapter 4) explores the husbandry practices and selection criteria of chicken producers in Northwest Ethiopia. In this chapter, data collected from a total of 360 households from six districts (stratified into lowland, midland, and highland agro-ecologies) was analyzed. In the study area, egg production performance was a priority by chicken owners when selecting female chickens across all agro-ecologies. For male chickens, plumage color, appearance, and growth rate were the main traits considered. Farmers primarily raised chickens for income generation through the sale of eggs and birds. There were significant differences among agro-ecologies in terms of chicken feeding management, housing, chicken flock composition, brood modification methods, and reproductive performance traits. The inbreeding coefficient was higher in the highland agro-ecology compared to the midland and lowland areas. To enhance chicken productivity sustainably, breeding programs should align with farmers' production objectives and trait preferences specific to each agro-ecology. The second manuscript (Chapter 5) focuses on characterizing the morpho-biometric variations of indigenous chicken ecotypes in Northwest Ethiopia. Sampling was done using a multi-stage purposive, stratified, and random approach. Morpho-biometric data collected from a total of 1200 adult chickens were analyzed for 12 qualitative and 11 quantitative traits. Red plumage color, white and red earlobe color, and yellow shank color were the most prevalent trait categories. Body measurements were significantly influenced by sex, agro-ecology, location, and the interaction of sex and location. Shank traits (Shank length and circumference) x exhibited high discriminatory power in both sexes. Female and male sample populations were classified with overall rates of 57.47% and 69.97%, respectively. Significant squared Mahalanobis distances were observed between locations/sites. Canonical variates analysis separated sample populations based on location. Cluster analysis classified the indigenous chickens into four ecotypes: ecotype 1 (Banja, Dembecha, and Aneded), ecotype 2 (North Achefer), ecotype 3 (Sinan), and ecotype 4 (Jawi). The third manuscript (Chapter 6) was based on an on-station comparison of the growth performance of indigenous chickens and evaluates the effect of Enteromorpha polysaccharide (EP) supplementation on their growth. A total of 180 indigenous chicken ecotypes (Sinan, Dembecha, North Achefer, and Jawi) were used in the study. Both ecotype and sex had a significant effect on body weight and average daily gain (ADG). Jawi ecotype exhibited the highest final body weight and ADG, followed by North Achefer. Males had higher body weight and ADG than females. Enteromorpha polysaccharide supplementation resulted in significantly higher body weight and ADG compared to non-supplemented chickens. The interaction between ecotype and feed type was not significant, except at week nine. Sinan ecotype showed the highest survivability rate in the first four weeks. Overall, Jawi and North Achefer ecotypes performed better in terms of growth, while Sinan ecotype showed relatively higher survivability. Supplementation of EP showed potential for improving chicken growth. The fourth manuscript (Chapter 7) was about the anticoccidial potential of Enteromorpha prolifera polysaccharide in indigenous chickens in Northwest Ethiopia. The study included 78 male indigenous chickens divided into two treatment groups: EP non-supplemented and EP supplemented. Each group had five replications. After 14 days of EP supplementation, chickens were inoculated with 1.5×10 mixed Eimeria oocysts. The EP-supplemented chickens exhibited significantly lower oocyst counts and less severe lesion scores compared to non-supplemented chickens. The EP supplementation provided relatively a higher protection rate against lesions and resulted in higher weight gain. Enteromorpha polysaccharide showed promise as a potential strategy for combating coccidiosis in chickens. Further research is needed to understand the mechanisms underlying its protective effects.

Designing Community-Based Breeding Program For Sustainable Utilization of Farta Sheep Genetic Resources in Northwest Ethiopia

2026-09-04T06:58:28Z

Designing Community-Based Breeding Program For Sustainable Utilization of Farta Sheep Genetic Resources in Northwest Ethiopia Shenkut, Abiye The overall aim of this dissertation was to develop a community-based breeding program for sustainable use of Farta sheep genetic resources in northwest Ethiopia. The specific objectives were: 1) identifying sheep breeding practices and trait preferences; 2) evaluating the growth performance, lamb survival and economic benefits of Farta and their crosses with Washera sheep; 3) estimating economic values (EV) of traits; 4) estimating the genetic and phenotypic parameters; 5) evaluating the efficiencies of village-based selection schemes. Methodologically, sheep breeding practices and trait preferences of smallholder farmers were identified using survey and choice experiment approaches. For both approaches, data were collected from 370 farmers in three districts (Estie = 117, Farta = 125 and Lay Gayient = 128). The choice data were analyzed using the generalized multinomial logit model, while the weighted indices were calculated to describe the rank data. Subsequently, the growth performance and lamb survival of Farta and its cross with Washera sheep were compared using data collected from 4318 sheep (3195 crossbreds with 50% Washera, 115 with 75% Washera and 1008 pure Farta). The growth and survival data were analyzed using the general linear and Cox regression models, respectively. Farmers’ perceptions about the Washera-Farta crossbreds were examined using qualitative data generated through interviewing 53 farmers among those who participated in the crossbreeding program. In addition, economic valuation based on hedonic price modeling was conducted using data collected from 216 Washera-Farta crossbreds and Farta sheep traded in the local market. The growth and lamb survival data collected from the Farta sheep and Washera-Farta crossbreds were also used to derive EV for various traits and estimate the genetic and phenotypic parameters for growth and pre-weaning lamb survival traits. The five models evaluated for genetic and phenotypic parameters estimation were: 1) a model with random effect of direct animal genetics; 2) direct animal genetics with the permanent environment; 3) direct animal and maternal genetics; 4) a model with all the three random effects; 5) logit transformed form of model 4 (only for pre-weaning lamb survival). Lastly, the biological and economic efficiencies of three selection schemes were evaluated using the findings obtained in specific objectives 1 to 4 as input parameters. The schemes were one-stage selection at 6 months (I) or yearling age (II) and two-stage selection with the first at 6 months using a 50% selection proportion and the second at the yearling age (III). All schemes were evaluated with three levels of ram selection proportions (P = 0.05, 0.1 and 0.2) and four flock sizes (600, 1200, 1800 and 2400 breeding ewes). The results of the questionnaire survey showed that the average Farta sheep flock size per farmer was about 10.21±4.79 sheep. Having the highest index value of 0.36, income generation was ranked as the primary reason for keeping sheep, followed by meat consumption (0.31) and manure production (0.16). The majority of the smallholder farmers (91%) have the experience of selecting breeding rams and ewes within their flock using diverse criteria. Given the highest index value of 0.34, body size was ranked as a primary ram and ewe selection criterion, followed by coat color. Furthermore, choice modeling results revealed that good tail type, large body size and brown coat color were the most preferred attributes for breeding rams. For breeding ewes, the highly preferred attributes were good mothering ability, brown coat color and large body size. Regarding the growth performance of Farta and its crosses with Washera sheep, the least-squares means (LSM) of birth weight were 2.83±0.06, 3.16± 0.06 and 3.24±0.08 kg for Farta, 50 and 75% Washera crossbreds, respectively, in which both crossbred genotypes were significantly heavier than Farta sheep (P<0.001). However, Farta sheep were significantly heavier in weights at weaning age and 6 months than both crossbred genotypes (P<0.001). The yearling weights among the three genotypes were not statistically different (P>0.05), with the LSM being 22.17±0.33, 21.92±0.31 and 23.25±0.87 kg for Farta, 50 and 75% Washera crossbreds, in the order mentioned. The proportions of lambs that survived up to a yearling age were 89, 82.5 and 70% for Farta, 50 and 75% Washera crossbreds, respectively. All the interviewed farmers preferred keeping Washera crossbreds to Farta sheep for reasons such as a relatively faster growth at an early age, a large body frame, good coat color and a high market price of the crossbreds. The hedonic price model revealed that breed type was among the various factors that had significant influences on price (P<0.001) in which the Washera-Farta crossbreds had about 12.7% higher price than Farta sheep. Concerning EV estimates for production traits, it was found that a unit genetic change for weight at weaning, six months of age, in yearlings and mature ewes had resulted in EV of US$ 1.46, 0.60, -0.04 and -0.24 per ewe per year, respectively. In addition, the EV for the number of lambs weaned per ewe bred, ewe fertility rate, lambing interval, post-weaning lamb survival and mature ewe survival were US$ 0.59, 0.37, 0.16, 0.53 and 0.86, in the order given. Analysis of the sensitivity of EV to fluctuations in the price of input and output parameters revealed that the marginal change in profit was more affected in most traits when the price of live weight was altered rather than feed cost. Comparisons of the various genetic models showed that model 2 for birth weight and model 3 for weaning weight, pre-weaning daily gain and six-month weight were found to be more appropriate for genetic parameters estimation. However, model 4 was conceptually more insightful to describe the variations in yearling weight and pre-weaning lamb survival. Accordingly, the direct heritability for birth weight, weaning weight, pre-weaning daily gain, six-month weight, yearling weight and pre-weaning lamb survival were 0.08±0.03, 0.20±0.05, 0.15±0.05, 0.24±0.06, 0.29±0.14 and 0.14±0.04, respectively. The maternal heritabilities were 0.29±0.05, 0.31±0.05, 0.40±0.05, 0.15±0.57 and 0.02±0.15 for weaning weight, pre-weaning daily gain, six-month weight, yearling weight and pre-weaning lamb survival, respectively. The genetic correlation between birth weight and pre-weaning lamb survival was negative (-0.36±0.22). For the other pairs of traits, genetic correlations ranging from 0.10±0.16 between yearling weight and preweaning lamb survival to 0.98±0.01 between weaning weight and pre-weaning daily gain were estimated. Finally, the analysis of the efficiencies of the three alternative selection schemes revealed that the highest annual selection response for each scheme was predicted when P = 0.05, while the lowest estimates appeared at P = 0.20. It was also observed that increasing flock size had little effect on the genetic progress but significantly reduced the rate of inbreeding across the studied schemes. The annual economic responses estimated for schemes I, II and III varied from US$ 0.393 to 0.591, 0.589 to 0.879 and 0.494 to 0.744, respectively. In other words, the annual economic gain in scheme II was higher by 34 and 16% than those predicted for schemes I and III, respectively. Operationally, scheme I is more feasible than other schemes but offers less economic benefit, while scheme II is relatively easier to implement than scheme III and provides higher annual economic gains than schemes I and III. Overall, implementing scheme II with P = 0.05 and flock size of 1200 ewes would be appropriate for the genetic improvement of Farta sheep through a community-based breeding approach. Given the crossbreds’ low survival rate and absence of growth superiority at the marketing and breeding ages, Farta sheep genetic improvement through Washera ram-based crossbreeding was not found to be effective under the existing low-input production system. However, considering the preference of farmers and the price advantage in the local market, Washera ram-based crossbreeding could still be an option to improve the livelihood of farmers in areas not addressed by the community-based selection program if the existing sheep management practice is improved.

Quantifying Genetic Diversity and Designing Community-Based Breeding Program for Indigenous Sheep in Northwestern Ethiopia

2026-09-04T06:51:50Z

Quantifying Genetic Diversity and Designing Community-Based Breeding Program for Indigenous Sheep in Northwestern Ethiopia Asmare, Sisay In Ethiopia, there are 32.85 million sheep, more than 99% of which are indigenous. However, the productivity of local sheep under traditional production system is low with high mortality of lambs. Between sheep breed differences in performance do exist and have begun to attract some research attention in recent years. Yet, little selection has been undergone for improved meat production and true breed potentials are not known and not all breeds have been sufficiently well characterized. There is a need to better acknowledge the unique features of these breeds, their products, their socio-cultural and religious uses, and their production systems. Multiple-visit, multiple-subject survey was conducted to characterize sheep production system, growth and reproductive performance, phenotypic features and genetic diversity study and generate information’ to design sheep breeding schemes. Purposive sampling method was employed to select study areas or districts and households engaged in sheep production. Pre-teested semi-structure questionnaire was administered for data collection. Data collection was carried out for two years from September, 2017 to October, 2019 G.C. Households under investigation have a small patch of land. Mean ±SD values of land holding per household of Burie, Mandura and Quara were 1.03±0.89 ha, 2.66±1.61 ha and 11.46±5.76 ha, respectively, resulting in insufficient pasture and feed shortages. Feed shortage, disease and parasites and lack of input were prioritized as major challenges of sheep production. The growth and reproductive performances traits of Washera and Gumuz sheep were comparable to other Ethiopian and African sheep. Breed type affected live weight significantly (P<0.001). Average age at first lambing and lambing interval were also affected by breed significantly. Body weight recorded for Washera, Gumuz and Rutana Sheep were 27.5, 26.89 and 38.71 kg, respectively. Chest girth and body length were best body weight predictors for Gumuz female sheep at p<0.001 level of significance. Tail length, ear length and body length were best body weight predictors for Gumuz male sheep at p<0.001 level of significance. For Washera female sheep, tail length, chest girth, height at withers and body length were best body weight predictors at p<0.001 level of significance. Tail length, chest girth and head length were best body weight predictors for Washera male sheep at p<0.001 level of significance. Higher mean values of morph metric traits were recorded canonical bone length. The variations in phenotypic features need to be supplemented by molecular diversity study. Clustering analysis using principal component (PC1) differentiates Rutana from Gumuz and Washera sheep supporting this variation. Polymorphic information content was 0.89, 0.90 and 0.88 for Gumuz, Rutana and Washera sheep, respectively. These values could be recognized as reasonably (moderately) informative to carry out genetic diversity study. Expected heterozygosity was found to be higher than observed heterozygosity attributed to the discrepancy to forces such as inbreeding. Observed heterozygosity ranged from 0.33 in Gumuz to 0.34 in Rutana and Washera sheep. Expected heterozygosity ranged from 0.37 in Rutana to 0.38 in Gumuz and Washera sheep. Higher inbreeding coefficient (0.12) was recorded for Gumuz sheep compared to 0.09 of Rutana and Washera sheep. Our whole-genome SNP analysis revealed high variation within populations. These within-breed variabilities were used as input for designing a selective breeding program. Phenotypically, two highly rated selection criteria (body size and litter size) were preferred for Gumuz and Washera ewe. Improving 25 kg sale weight (at yearling age) and the number of lambs qualifying for the market and home consumption were the proposed breeding objectives or goals. Genetic gain predicted for six- month weight of Gumuz and Washera sheep were 0.46 and 0.60 kg of live weight, respectively. Genetic gain predicted for yearling weight of Gumuz and Washera sheep were 0.58 and 0.66 kg of live weight, respectively. A sheep breeding program with 10% selection proportion and one year ram use for breeding was recommended giving special emphasis to yearling weight.