Growth curve analysis in different generations of Boer x Central Highland goats using alternative estimation models.

Growth curve analysis can help to optimize the management, determine nutritional requirements, predict the weight of animals at a specific age, and to select highly productive animals. Therefore, this study aimed to find the best-fitted nonlinear functions to provide a specific shape of the growth curve from birth to yearling age in different generations of Boer x Central Highland goats. Gompertz, Logistic, Brody, Von Bertalanffy, Monomolecular, Negative exponential, and Richards models were evaluated to quantify their ability to describe the biological growth curve. Root mean square error (RMSE), Bayesian information criterion (BIC), adjusted coefficient of determination (AdjR2), and Akaike's information criterion (AIC) were used to evaluate the goodness of fit and flexibility of the models. Data were analyzed using the nonlinear regression procedure of SAS. High AdjR2 and lower AIC, BIC, and RMSE values are indicators of best-fitted model. The best-fitting model for the first filial generation (F1), second filial generation (F2), and male goats' growth data was Brody function, whereas the Richards model, followed by Brody, best described the growth of third filial generation (F3) and female goats. The values of parameter A (asymptotic weight) for F1, F2, F3, female, and male goats based on the Brody model were 30.5±1.32, 28.2±1.38, 24.4±1.04, 27.8±0.94, and 29.8±1.32 kg for F1, F2, F3, female, and male goats, respectively. As per the best-fitted growth function, the asymptotic weight tended to reduce when the filial generation increased. The asymptotic weight for male goats was higher than for female goats. F1 had a slightly small value of parameter K, followed by F2 and F3. Both males and females had similar maturity rates. Based on the Brody function, the correlation between maturation rate and mature weight was high (-0.98, P<0.001). The correlation estimates for A-B and B-K were 0.27 and -0.15, respectively. Brody was best fitted for most goat categories, although Richards, followed by Brody, was best fitted for female and F3 goats. Besides, Brody could be better than Richards due to the ease of interpretation, convergence, and applicability for a small sample size. Therefore, the Brody function can predict the mature body weight, maturation rate, and growth rate of Boer x Central Highland goats and be used to formulate breeding and management strategies for profitable goat farming.

Epidemiology and identification of Eimeria species affecting poultry in East Gojjam Zone, North West Ethiopia.

BACKGROUND: Despite the expansion of modernized poultry farming in Ethiopia, the presence of high prevalence of Eimeria species is the bottleneck in the sector causing high morbidity and mortality rate in poultry. OBJECTIVES: The objectives of this study were to estimate the prevalence and identify Eimeria species and investigate the major risk factors. METHOD: A cross-sectional study was conducted from November 2019 to April 2020 in East Gojjam Zone, North West Ethiopia. A total of 384 chickens were used. Both floatation and McMaster coprological techniques were employed. Univariate and multinomial logistic regression was used to calculate the odds ratio for the associated risk factors. Analysis of variance was used to analyse differences in Eimeria oocyst counts among the groups. RESULTS: Overall prevalence of Eimeria species in poultry from the study area was 26.5%. Age (OR = 0.25, p = 0.001), management system (OR = 12.44, p = 0.001) and production system (OR = 0.37, p = 0.001) were found significantly (p < 0.05) associated with the risk of Eimeria species in poultry. The mean Eimeria oocyst count was significantly different by age and management system (F = 6.526, p = 0.002), (F = 5.369, p = 0.005), respectively. The mean Eimeria oocyst count was significantly greater in 6-12 weeks (p = 0.004) and <6 weeks of age (p = 0.025). A total of 6 Eimeria species were identified. Eimeria tenella (46.07%), Eimeria necatrix (24.5%) and Eimeria acervulina (8.82%) were the most common Eimeria species encountered. CONCLUSION: The prevalence of Eimeria species was higher in poultry in North West Ethiopia. Therefore, tailor-made intervention is required to mitigate risk factors and reduce the prevalence of Eimeria species in poultry from the study area.

Growth and growth curve analysis in Dorper × Tumele crossbred sheep under a smallholder management system.

This study aimed to evaluate the growth performance and Kleiber ratio (KR) and to determine the growth curve of Dorper × Tumele sheep under a smallholder management system. Growth and efficiency-related traits were analyzed by using the general linear model (GLM) procedure of SAS. Gompertz, Logistics, Brody, Monomolecular, and Negative exponential models were used to determine the growth curve, and growth curve parameters were estimated via the nonlinear regression model (NLIN) procedure of SAS. The overall least-squares means of the birth weight, weaning weight, 6-month weight, and yearling weight were 3.29, 13.7, 17.3, and 23.4 kg, respectively. Dorper × Tumele lambs grew faster during the preweaning period (115.3 ±â€…1.19 g day-1) than during the postweaning periods (44.1 ±â€…1.26 g day-1 to 33.5 ±â€…1.13 g day-1). Likewise, a higher KR was observed during the pre-weaning age (16.1 ±â€…0.08 g/day/kg0.75) than during postweaning periods (5.08 ±â€…0.13 g/day/kg0.75 to 3.10 ±â€…0.09 g/day/kg0.75). Brody, a model without an inflection point was the best-fitted growth function for Dorper × Tumele sheep under a smallholder management system. The highest and lowest asymptotic weight was observed for Brody (23.8 ±â€…0.22 kg) and Logistics (20.7 ±â€…0.11 kg) models, respectively. The maturation rate ranged between 0.21 (Brody) and 0.66 (Logistics). Based on the Brody model, the correlation between asymptotic weight and maturity rate was -0.92. The growth parameter estimate in this study indicates that Dorper × indigenous sheep had a better speed to achieve mature weight and the early mature crossbred sheep are less likely to exhibit high adult weight. The rapid growth of crossbred sheep during the early period can provide more profit to the farmer by reducing the cost of sheep production inputs. Therefore, crossing Tumele with Dorper sheep and integrating with improved management would be suggested to improve productivity and profit from sheep production.

Epidemiology of Ixodid tick infestation and tick-borne haemopathogens in small ruminant from Enarje Enawuga, North Western Ethiopia.

BACKGROUND: Small ruminant playing significant economic development and cultural roles for smallholders and reared in different agroecological systems in Ethiopia. However, ticks and tick-borne haemopathogens are major threats to the health of small ruminants leading to loss of production and productivity in Ethiopia especially in north-western Ethiopia, due to climate and agroecological system favourable to the tick survival in the area. OBJECTIVES: The objectives of this study were to determine the prevalence of Ixodid tick infestation and tick-borne haemopathogens, to identify the existing Ixodid tick species and to investigate major risk factors associated with tick infestation and tick-borne haemopathogens. METHODS: A cross sectional study was conducted on 396 small ruminants (sheep =198 and goats = 198). Ticks were identified to the species level according to their morphological key structures. Thin blood smear were prepared and laboratoricaly examined to investigate tick-borne haemopathogens. Logistic regression was employed to assess the association between potential risk factors with tick infestation and tick-borne haemopathogens. RESULTS: The overall prevalence of tick infestation and tick-borne haemopathogens were 47.22% and 4.29%, respectively. Age, species, body condition, agroecological system and season were found significantly (p < 0.05) associated with tick infestation. Season was found to be significantly (p < 0.05) associated with occurrence of tick-borne haemopathogen. Amblyomma variegatum (18.2%) and Rhipicephalus evertsi evertsi (13.4%) were the predominant tick species encountered. Anaplasma ovis, Anaplasma marginale and Babesia ovis were prevalent tick-borne haemopathogens. CONCLUSIONS: The present study reported that there was higher tick infestation and tick-borne haemopathogens infections on small ruminants in the study area. Therefore, based on tick epidemiology, a strategic tick control programs were needed in this region. Further detailed studies on the role of Ixodid tick species in causing tick-borne diseases in small ruminants and their economic impact on livelihoods should be conducted.

Genetic and non-genetic parameter estimates for growth traits and Kleiber ratios in Dorper × indigenous sheep.

Genetic improvement programme will only be successful when accompanied by a good understanding of the influence of different environmental factors, knowledge of the genetic parameters and the genetic relationships between the traits of interest. This study aimed to evaluate the influence of non-genetic factors on growth traits and Kleiber ratios and to estimate genetic parameters for early growth traits in Dorper × indigenous crossbred sheep. The effects of fixed factors were analysed by the general linear model procedure of statistical analysis system, while the genetic parameters were estimated using a WOMBAT computer program fitted animal model. The overall least-square mean for birth weight (BRW), weaning weight (3MW), six-month weight, nine-month weight, and yearling weight were 3.03 ± 0.02, 14.5 ± 0.18, 20.4 ± 0.26, 24.8 ± 0.31, and 28.3 ± 0.40 kg, respectively. The overall least-square mean for Kleiber ratio from birth to weaning (KR1), weaning to six months, six to nine months and nine months to yearling age were 16.8 ± 0.10, 6.41 ± 0.17, 4.55 ± 0.21 and 3.38 ± 0.20 g/kg of metabolic weight, respectively. The inclusion of maternal genetic effect had a significant influence on BRW, and it explains 20% of the phenotypic variation. The total heritability estimates for BRW, 3MW, birth to weaning average daily weight gain and KR1 were 0.10, 0.14, 0.16 and 0.12, respectively. The phenotypic correlation varied from -0.11 ± 0.05 to 0.98 ± 0.02, whereas the direct genetic correlation ranged from -0.32 ± 0.40 to 0.98 ± 0.17. The mean inbreeding coefficient was 0.105% with an annual rate of 0.02%. The heritability estimates for growth traits and Kleiber ratio suggest that slow genetic progress would be expected from the selection. However, the integration of selection with crossbreeding programme can enhance genetic gain. Therefore, selection should be conducted based on breeding values estimated from multiple information sources to increase the selection response.

Evaluation of growth and efficiency-related traits of different levels of Boer x Central Highland crossbred goats.

The growth and efficiency-related traits of the Boer x Central Highland goats raised semi-intensively were evaluated. Besides, genetic and non-genetic factors affecting growth and efficiency-related traits were identified. Data were collected over a period of nine years in a flock of Boer crossbred goats and analyzed using general linear model procedure of SAS. The overall least-squares mean live weight at birth, 3-, 6-, 9- and 12 months of age were 2.52 ± 0.01, 9.81 ± 0.13, 13.8 ± 0.15, 17.8 ± 0.19, and 20.5 ± 0.29 kg, respectively. The average weight gains from birth to 3 months, 3 to 6, 6 to 9 and 9-12 months of age were 80.3, 37.5, 41.9, and 31.2 g day-1, respectively. Boer blood level, birth type, season and year of kidding had a significant effect on growth traits. The overall least-squares mean of Kleiber ratio from birth to 3 months, 3-6 months, 6-9 months, and 9 month to yearling age were 13.99 ± 0.11, 5.23 ± 0.14, 4.66 ± 0.16, and 2.95 ± 0.18, respectively. Parity, birth type, Boer blood level, season and year of birth had a significant influence on the expression of efficiency-related traits (Kleiber ratios) in different growth phases. In terms of growth performance and efficiency-related traits, F2 and F3 crossbred goats did not show any benefit over F1 crossbred goats. Increasing Boer blood level above 50% would be worthless under the existing minimal input production system. Therefore, besides to improving the management of goats, producing the first filial generation would be suitable for medium to high input production systems.

Estimation of genetic parameters for growth traits and Kleiber ratios in Boer x Central Highland goat.

Accurate performance evaluation and genetic parameters estimation are the prerequisites for any successful genetic improvement program. This study was conducted to estimate genetic parameters for growth and Kleiber ratio traits in Boer x Central Highland goats. On-station data collected from 2009 to 2018 were utilized for the study. A general linear model procedure of the Statistical Analysis System (SAS, version 9.0) was used to analyze fixed effects, and genetic parameters were estimated using the WOMBAT software fitted animal model. The log-likelihood ratio test was used for selecting the best fitted model. Based on best fitted models, the total heritability (h2t) estimate for birth weight (BWT), weaning weight (WWT), six-month weight (SMWT), nine-month weight (NMWT), and yearling weight (YWT) were 0.38, 0.12, 0.05, 0.30, and 0.28, respectively. The total heritability (h2t) estimates for weight gain from birth to weaning (ADG1), 3 to 6 months (ADG2), 6 to 9 months (ADG3), and 9 to 12 months of age (ADG4) were 0.09, 0.08, 0.16, and 0.14, respectively. The heritability estimates for Kleiber ratios in different growth phases were found to be low (0.09 to 0.18) based on the selected models. Even with this figure, including the Kleiber ratio in the selection criteria would be imperative to improve the feed efficiency of crossbred goats. The direct genetic correlation estimates among growth traits range from 0.60 ± 0.14 to 0.97 ± 0.12. Except for NMWT, ADG4, and Kleiber ratio from 9 months to yearling age, the maternal effect had a significant influence on all considered traits. However, the contribution of the maternal genetic effect was more important for early growth traits. Thus, considering both the direct additive genetic effect and the maternal genetic effect is imperative for accurate genetic evaluation and for high selection response. The moderate heritability estimates for most of the growth traits implies the possibility of selection in conjunction with crossbreeding for a better genetic response. The positive and high genetic correlation estimates among growth traits confirm the possibility of a selection of goats at an early age.

Epidemiological study on calf diarrhea and coccidiosis in dairy farms in Bahir Dar, North West Ethiopia.

BACKGROUND: A longitudinal prospective study was conducted from October 2017 to April 2018 on calf diarrhea and coccidiosis in dairy farms in Bahir Dar, North West Ethiopia with the objectives of determining the incidence of calf diarrhea and calf coccidiosis from diarrheic calves, assessing the major risk factors associated with calf diarrhea and coccidiosis and identifying the existing Eimeria species. A total of 237 calves, 86 calves from 52 smallholder dairy farms and 151 calves from 8 large dairy farms, were used for this study. Fresh fecal samples were collected from 86 diarrheic calves for identification of Eimeria species. RESULTS: Overall incidences of calf diarrhea and coccidiosis found in this study were 33.5 and 20.1%, respectively. In total, 19 potential risk factors were investigated for their association with calf diarrhea and coccidiosis from diarrheic calves using Cox regression. Age of calf (HR = 2.057, P = .002), body condition (HR = 1.802, P < .001), house condition (HR = 2.072, P = .004) and age at first colostrum feeding time (HR = 2.107, P = .002) were found significantly (P < 0.05) associated with the risk of diarrhea by multivariate Cox regression. Among the risk factors tested, age (HR = 13.36, P < .001) and sex of calves (HR = 3.500, P = .020) were found significantly (P < 0.05) associated with coccidiosis by multivariate Cox regression. A total of nine Eimeria species were identified. E. bovis (28.6%), E. zuernii (19.0%) and E. auburnensis (14.3%) were the most common Eimeria species encountered. CONCLUSION: The incidence of calf diarrhea and coccidiosis was high in the dairy herds in North West Ethiopia. Therefore, sound dairy calf management practices are needed to mitigate risk factors for calf diarrhea and coccidiosis with a view to reducing the incidence of calf diarrhea and coccidiosis in Ethiopian dairy farms.

Survival analysis and reproductive performance of Dorper x Tumele sheep.

Productivity and profitability of sheep farming are highly influenced by lamb survival and ewe reproductive performance. Thus, this study was conducted to evaluate the survival and reproductive performance of crossbred sheep. Data collected from 2009 to 2018 from Sirinka sheep breeding stations were utilized for this study. Survival analysis was conducted by using Survival Kit 6.12 software with the Weibull model and the general linear model of SAS 9.0 was used to analyze reproductive traits. The overall mean survival rate of Dorper x Tumele crossbred lambs at 3, 6 and 12 months of age were 86.0, 76.6, and 67.9%, respectively. About 46.8% of mortality from the total death was observed during the first 120 days of life. Gastrointestinal parasites, pneumonia and septicemia were the major causes of lamb mortality. Birth weight, birth type, sex and year of lambing were the most important risk factors for survival of crossbred lambs. The overall least-squares means for litter size at birth, litter size at weaning, total litter weight at birth and total litter weight at weaning were 1.10 lambs, 0.94 lambs, 3.28 kg and 15.5 kg, respectively. Birth type, sex and year of lambing were the most determinants of ewe productive traits. Tumele and their crossbred sheep had good mothering ability necessary to successfully raise lambs to weaning. The current crossbreeding program which aims to improving growth performance had a positive influence on the survival rate of lambs. Improvement of environmental in the flock, special care for small lambs and indirect selection based on birth weight would lead to further survival improvement.

Modeling the transmission dynamics of foot and mouth disease in Amhara region, Ethiopia.

Foot and mouth disease (FMD) is contagious, acute viral disease of all cloven-hoofed animals. The disease is endemic in Ethiopia and causes multiple outbreak every year all over the country. While it is important to understand to the transmission dynamics of FMD outbreaks for appropriate control intervention, no such study has been done in Ethiopia. Thus, the aims of this study were to estimate the basic reproduction number (R0) of FMD and simulate FMD transmission dynamics of FMD in Amhara region of Ethiopia. Basic reproduction number (R0) was estimated from age stratified sero-prevalence data through maximum likelihood estimation. A stochastic SIR (susceptible-infectious-recovered) compartmental FMD model was formulated and parameterized using literature and age stratified sero-prevalence field data. The R0 of FMD in the region was estimated to be 1.27 (95%CI: 1.20-1.34). The simulation of the SIR model showed only 24% (95% CI: 16-32%) of the infection introduced in the region caused major outbreaks. Out of the major outbreaks 25% of them tend to persist in the region. Major outbreaks cause 38.9% (95% CI: 38.8-39.1%) morbidity and 0.0019% (95% CI: 0.0018-0.0020%) mortality in cattle and the outbreaks stayed for an average of 690 days (95%CI: 655-727). Validation of the model prediction with farmer's field experience indicated a fairly similar result especially for the predicted morbidity caused by outbreaks. This study revealed low transmission of FMD within the Amhara region cattle population indicating not very high vaccination coverage is needed, if control through vaccination is envisaged at regional level. However, owing to several simplified assumptions made during the modeling, this conclusion should be taken cautiously.

Sero-Epidemiology of Foot and Mouth Disease in Domestic Ruminants in Amhara Region, Ethiopia.

This study involved cross-sectional serological and questionnaire-based surveys to investigate the sero-epidemiology of foot and mouth disease (FMD) in domestic ruminants, and farmers' knowledge and practices about the disease in the Amhara region of Ethiopia. A multistage cluster sampling was carried out to select domestic ruminants for serological sampling and for the interview with farmers. A total of 1,672 sera samples were collected and tested using a 3ABC-Enzyme Linked Immunosorbent Assay, and 170 farmers were interviewed. An overall FMD apparent seroprevalence of 11.48% (95% CI: 7.52-17.14%) was recorded in the domestic ruminants. The overall true prevalence was 12.04%. The seroprevalence of FMD was higher in cattle (14.37%) than in goats (7.10%) and sheep (7.07%). The age stratified seroprevalence in the districts showed that 66.67% of the districts studied experienced a FMD outbreak within the preceding year of the study time. A mixed effect logistic regression analysis revealed that agroecology, the production system and the age of the animal was significantly associated with FMD seropositivity in cattle (P < 0.05). A statistically significant (P < 0.05) positive correlation (r = 0.93) was observed between cattle and small ruminant FMD seroprevalences. About 82% of the farmers interviewed knew of FMD and 85% of them had experienced the disease in their own herds before. The farmers mostly employ traditional means to control FMD. In conclusion, the findings of the study indicated that FMD is a prevalent disease in the Amhara region with more importance in the intensive production systems and the lowlands of the region. High correlation in seroprevalence between small and large ruminants indicated a possible cross transmission between these species. Therefore, small ruminants should not be overlooked in FMD control. Farmers in the region have a good level of knowledge about the disease; however, currently they heavily rely on traditional practices primarily focused on treating wounds of infected animals. This calls for extension work on available effective preventive measures of the disease, such as vaccination and movement restriction.