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.

Characterization of the production system and breeding practices of indigenous goat keepers in Hai district, Northern Tanzania: implications for community-based breeding program.

Indigenous breeding practices of the farmers and the livestock production system form the bases for designing community-based breeding programs. The aim of this study was to characterize production system and examine breeding practices of the indigenous goat farmers in Hai district in Northern Tanzania to determine their relevance in establishing a community-based breeding program in the area. A cross-sectional survey was conducted in which information was collected from 160 households randomly selected from 6 villages. Average household herd was 29.2 goats with majority keeping less than 20 goats. Major reasons for keeping goats were income generation, meat and milk production. Controlled mating was practiced mainly using apron and castration. Castration was practiced using traditional methods to control breeding and improve meat quality. Farmers in the study area had large goat flocks and a small buck to doe ratio. Farmers do not have a good understanding of inbreeding and its negative effects but practise other good breeding methods which could impact the productivity of their animals. Diseases and feed shortages were the main constraints to production. Opportunities exist for a community-based breeding program to genetically improve goat productivity.

Giving birth in Ethiopia: a spatial and multilevel analysis to determine availability and factors associated with healthcare facility births.

OBJECTIVE: To assess spatial variations in the use of healthcare facilities for birth and to identify associated factors. DESIGN: Cross-sectional analysis of population- and healthcare facility-based data. SETTING: Ethiopia Demographic and Health Survey (EDHS 2016) linked to Service Provision Assessment data (SPA 2014). POPULATION: A sample of 6954 women who gave birth in the 5 years preceding EDHS 2016 and 717 healthcare facilities providing delivery care. METHODS: Secondary data analysis of linked population and health facility data was conducted. Multilevel and spatial analyses were conducted to identify key determinants of women's use of health facilities for birth and to assess spatial clustering of facility births. MAIN OUTCOME MEASURE: Health facility birth. RESULTS: A one-unit increase in the mean score of the readiness of health facilities to provide basic emergency obstetric care (EmOC) was associated with a two-fold increase in the odds of facility birthing (adjusted odds ratio, aOR, 2.094, 95% CI 1.187-3.694). A woman's attendance for at least four antenatal care visits was significantly associated with facility birth (aOR 8.863, 95% CI 6.748-11.640). Distance to a healthcare facility was inversely related to a woman's use of facility birthing (aOR 0.967, 95% CI 0.944-0.991). Women in the richest wealth quintile were also more likely to have facility births (aOR 2.892, 95% CI 2.199-3.803). CONCLUSIONS: There were geographic variations in facility births in Ethiopia, revealing critical gaps in service availability and readiness. It is important to ensure that health facilities are in a state of readiness to provide EmOC. TWEETABLE ABSTRACT: Failure to ensure health facility readiness is associated with failure to give birth at a healthcare facility.

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.

Participatory identification of breeding objective traits and selection criteria for indigenous goat of the pastoral communities in Ethiopia.

A structured questionnaire, own-flock ranking experiment, and group discussions were undertaken to assess goat breeding practices and to identify traits of interest for genetic improvement of indigenous goats. Four pastoral villages in Ethiopia, namely, Jarso, Mesoya, Eleweya, and Dharito were selected based on their goat production potential, accessibility, and suitability to implement community-based breeding programs. A survey and flock ranking experiment involving 70 households and 199 goats were used. In flock ranking experiment, goat owners were asked to choose the first three superior and the worst doe within their own flock. They were also asked to provide their reason for ranking the animals. In addition, data on size traits, kid growth, kid survival, reproduction traits, and milk yield were recorded for each doe. Data obtained from questionnaire, flock ranking, and measurements were subjected to both qualitative and quantitative analysis. Large variation was observed between top and last ranked does in most of the traits and price, for example, in body weight (33.6 ± 0.88 vs. 25.2 ± 0.93 kg), doe's kid survival (92.1 ± 4.01 vs. 59.6 ± 4.48%) and doe's price (1367 ± 46.5 vs. 833 ± 46.9 (US$1 = 28.4 Ethiopian Birr) Ethiopian Birr). Mobility is practiced with a defined and known pattern; therefore, recruitment of mobile enumerators for data recording would assist in implementation of breeding programs. Breeding objective should emphasize mothering ability (kid growth and survival), milk yield of does, and coat color in all areas. Due to its good correlation with other traits like kid growth and pre-weaning kid survival, considering milk yield alone as selection criteria or giving more weight for milk yield in the breeding program could generate better genetic benefit. Setting-up breeding program should be based on full participation and context of pastoralists.

Improving ability of RSV microneutralization assay to detect G-specific and cross-reactive neutralizing antibodies through immortalized cell line selection.

Respiratory syncytial virus (RSV) is a significant cause of bronchiolitis and pneumonia. Protection against RSV is associated with neutralizing antibodies against the fusion (F) and attachment (G) glycoproteins. Several RSV vaccine candidates are in development, but their immunogenicity is hard to compare due to the little-understood differences between multiple RSV neutralizing antibody assays used. Existing assays utilize primarily Vero or HEp-2 cells, but their ability to detect G-neutralizing antibodies or antibodies against specific RSV strains is unclear. In this work, we developed an RSV microneutralization assay (MNA) using unmodified RSV and immortalized cell line derived from human airway epithelial cells (A549). Performance of A549-, HEp-2- and Vero-based MNA was compared under the same assay conditions (fixed amount of virus and cells) with regards to detection of neutralizing antibodies against RSV A or B viruses, G-reactive neutralizing antibodies, and effect of complement. Our results indicate that A549 cells yield the highest MNA titers, particularly in the RSV A/A2 MNA, are least susceptible to complement-enhancing effect of neutralizing titer readout and are superior to Vero or HEp-2 MNA at recognizing G-reactive neutralizing antibodies when no complement is used. Vero cells, however, can be more consistent at recognizing neutralizing antibodies against multiple RSV strains. The choice of substrate cells thus affects the outcome of MNA, as some immortalized cells better support detection of broader range of neutralizing antibodies, while others facilitate detection of G-targeting neutralizing antibodies, a long-thought prerogative of primary airway epithelial cells.

Investigations into nematode parasites of goats in pastoral and crop livestock systems of Ethiopia.

We generated epidemiological information on the prevalence of nematode parasites and possible resistance/resilience of goats in three areas, Bati, Shinille, and Borana, of Ethiopia. A total of 350 breeding does were randomly selected and monitored for one year. Fecal egg counts (FEC), packed cell volume (PCV), body weight (BW), body condition score (BC), and fecal larvae identification were done. In Borana, the long rainy season had higher FEC, lower PCV, lower BC, and smaller BW compared to dry and short rainy seasons (p < 0.01). For Bati and Shinille, the differences between the seasons were significant (p < 0.01) but not clear-cut. Breed differences were also evident (p < 0.01) on FEC, PCV, and BW. The mean FEC for Borana goat was 158.5 ± 1.12, whereas for Bati it was 38.9 ± 1.12. Age differences did not have effect on FECs, PCV, and BC. No differences in parasite load, as reflected by FEC, was verified between male and female goats. In the wet season, large numbers of larvae were recovered from the study sites except for Bati. In the three sites, Haemonchus contortus followed by Trichostrongylus colubriformis were the dominant species. In the dry season, however, very little number of larvae was recovered, only of H. contortus in Bati and of H. contortus and T. colubriformis in Borana. Generally, the level of nematode infection was low. Therefore, nematode parasites are not a major problem and strategic control program using broad spectrum anthelmintic is not advisable. Rather, monitoring parasite load and selective de-worming should be sufficient to reduce productivity loses and pasture contamination.

Conversion of finished leather waste incorporated with plant fibers into value added consumer products - An effort to minimize solid waste in Ethiopia.

Presently, the leftovers from leather product industries are discarded as waste in Ethiopia. The objective of the present study was therefore, to prepare composite sheets by incorporating various plant fibers like enset (Ensete ventricosum), hibiscus (Hibiscus cannabinus), jute (Corchorus trilocularis L.), palm (Phoenix dactylifera) and sisal (Agave sisal) in various proportions into the leather waste. Resin binder (RB) and natural rubber latex (NRL) were used as binding agents for the preparation of the composite sheets. The composite sheets prepared were characterized for their physicochemical properties (tensile strength, elongation at break, stitch tear strength, water absorption, water desorption and flexing strength). Composite sheets prepared using RB having 10% hibiscus, 20% palm and 40% sisal fibers showed better mechanical properties than their respective controls. In composite sheets prepared using NRL having 30% jute fiber exhibited better mechanical properties than its control. Most of the plant fibers used in this study played a role in increasing the performance of the sheets. However, as seen from the results, the contribution of these plant fibers on performance of the composite sheets prepared is dependent on the ratio used and the nature of binder. The SEM studies have exhibited the composite nature of the sheets and FTIR studies have shown the functional groups of collagen protein, cellulose and binders. The prepared sheets were used as raw materials for preparation of items like stiff hand bags, ladies' purse, keychain, chappal upper, wallet, wall cover, mouse pad and other interior decorating products. By preparing such value added products, we can reduce solid waste; minimize environmental pollution and thereby securing environmental sustainability.

System dynamics modeling in designing breeding schemes: The case of Menz sheep in Ethiopian highlands.

A comprehensive dynamic simulation model was developed to describe a community-based breeding program for the Menz sheep population of Ethiopia. Selection of male and female animals based on their own and maternal performance was simulated. The breeding goal traits were 6-mo weight, preweaning survival, and fertility rate. The model input data were obtained from the flock book, questionnaires, and references. The simulation model used a mix of deterministic and stochastic procedures to model the complex system. In the baseline scenario, the proportion of selected male and female animals varied between 20 and 30% and between 70 and 80%, respectively. A reasonable annual genetic gain was predicted for the breeding goal traits at the village level. For 6-mo weight and preweaning survival rate, the annual genetic gain varied from 0.213 to 0.214 kg and 0.255 to 0.256%, respectively. For fertility rate, an annual genetic gain of 0.063% was obtained. The predicted rate of inbreeding per year was between 0.094 and 0.116%. Furthermore, a scenario analysis was conducted by varying the proportions of selected animals. Annual genetic gains of 0.230 kg, 0.277%, and 0.069% were obtained for 6-mo weight, preweaning survival rate, and fertility rate, respectively, when the proportion of selected male and female animals decreased by 10%. The annual genetic gains decreased to 0.198 kg, 0.236%, and 0.059%, respectively, when the selection proportion of male and female animals increased by 10%. The lowest rate of inbreeding per year, ranging from 0.065 to 0.079%, was achieved when the selection proportion of selected male and female animals increased. The model is relevant for the step-by-step evaluation of more than one round of selection. It is flexible and usage driven. The model is a valuable tool to design different population structures and can be easily expanded to adopt different breeding strategies. Hence, the system dynamics modeling approach is a potential tool to describe complex breeding programs.

Comparative Proteomic Analysis of Mycobacterium tuberculosis Lineage 7 and Lineage 4 Strains Reveals Differentially Abundant Proteins Linked to Slow Growth and Virulence.

In order to decipher the nature of the slowly growing Mycobacterium tuberculosis (M.tuberculosis) lineage 7, the differentially abundant proteins in strains of M. tuberculosis lineage 7 and lineage 4 were defined. Comparative proteomic analysis by mass spectrometry was employed to identify, quantitate and compare the protein profiles of strains from the two M. tuberculosis lineages. Label-free peptide quantification of whole cells from M. tuberculosis lineage 7 and 4 yielded the identification of 2825 and 2541 proteins, respectively. A combined total of 2867 protein groups covering 71% of the predicted M. tuberculosis proteome were identified. The abundance of 125 proteins in M. tuberculosis lineage 7 and 4 strains was significantly altered. Notably, the analysis showed that a number of M. tuberculosis proteins involved in growth and virulence were less abundant in lineage 7 strains compared to lineage 4. Five ABC transporter proteins, three phosphate binding proteins essential for inorganic phosphate uptake, and six components of the type 7 secretion system ESX-3 involved in iron acquisition were less abundant in M. tuberculosis lineage 7. This proteogenomic analysis provided an insight into the lineage 7-specific protein profile which may provide clues to understanding the differential properties of lineage 7 strains in terms of slow growth, survival fitness, and pathogenesis.

Bayesian Estimation of Sensitivity and Specificity of Rose Bengal, Complement Fixation, and Indirect ELISA Tests for the Diagnosis of Bovine Brucellosis in Ethiopia.

Test evaluation in the absence of a gold standard test was conducted for the diagnosis and screening of bovine brucellosis using three commercially available tests including RBPT, CFT, and I-ELISA in National Animal Health Diagnostic and Investigation Center (NAHDIC) Ethiopia. A total of 278 sera samples from five dairy herds were collected and tested. Each serum sample was subjected to the three tests and the results obtained were recorded and the test outcomes were cross-classified to estimate the sensitivity and specificity of the tests using Bayesian model. Prior information generated on the sensitivity and specificity of bovine brucellosis from published data was used in the model. The three test-one population Bayesian model was modified and applied using WinBug software with the assumption that the dairy herds have similar management system and unknown disease status. The Bayesian posterior estimate for sensitivity was 89.6 (95% PI: 79.9-95.8), 96.8 (95% PI: 92.3-99.1), and 94 (95% PI: 87.8-97.5) and for specificity was 84.5 (95% PI: 68-94.98), 96.3 (95% PI: 91.7-98.8), and 88.5 (95% PI: 81-93.8) for RBT, I-ELISA, and CFT, respectively. In this study I-ELISA was found with the best sensitivity and specificity estimates 96.8 (95% PI: 92.3-99.1) and 96.3 (95% PI: 91.7-98.8), compared to both CFT and RBPT.

Self-organized nanoparticle photolithography for two-dimensional patterning of organic light emitting diodes.

We report a new simple and inexpensive sub-micrometer two dimensional patterning technique. This technique combines a use of a photomask featured with self-organized particles in the micro- to nano-meter size range and a photoresist-covered substrate. The photomask was prepared by depositing monodispersed silicon dioxide (SiO(2))- or polystyrene- spheres on a quartz substrate to form a close-packed pattern. The patterning technique can be realized in two configurations: a hard-contact mode or a soft-contact mode. In the first configuration, each sphere acts as a micro ball-lens that focuses light and exposes the photoresist underneath the sphere. The developed pattern therefore reproduces exactly the same spatial arrangement as the close-packed spheres but with a feature size of developed hole smaller than the diameter of the sphere. In the soft-contact mode, an air gap of few micrometers thick is introduced between the 2D array of self-organized spheres and the photoresist-covered substrate. In this case, a phase mask behavior is obtained which results in an exposure area with a lattice period being half of the sphere diameter. A 2D lattice structure with period and feature size of a developed hole as small as 750 nm and 420 nm, respectively, was realized in this configuration. We further applied this technique to host the deposition of organic films into the 2D nanostructure and demonstrated the realization of green and red nano-structured OLEDs.

Efficiency of selection for body weight in a cooperative village breeding program of Menz sheep under smallholder farming system.

We evaluated the efficiency of selection for body weight in a cooperative village breeding program for Menz sheep of Ethiopia under smallholder farming system. The design of the program involved organizing villagers in a cooperative breeding group to implement selective breeding of their sheep. The program was jump-started through a one-time provision of elite rams from a central nucleus flock, but subsequent replacement rams were selected from within the village flocks. We also evaluated body weight trends in a village where cooperative breeding was not implemented and individual farmers managed their flocks under traditional breeding practices. Under traditional breeding practices, genetic progress over 8 years either stagnated or declined in all the weights recorded. In the cooperative villages, selection differentials of 2.44 and 2.45 kg were achieved in 2010 and 2011 selection seasons, respectively. Birth weight, 3-month weight and 6-month weight increased, respectively, by 0.49, 2.29 and 2.46 kg in the third-generation lambs over the base generation. Improved rams supplied from the central nucleus flock gave an initial genetic lift of 14.4% in the 6-month weight. This was higher than the gain achieved from selection in the village flocks, which was 5.2%. Our results showed that village-based genetic improvement in body weights under smallholder conditions could be feasible if appropriate designs are adopted and that commencing with elite central nucleus rams help jump-start village-based programs.

Congruence between selection on breeding values and farmers' selection criteria in sheep breeding under conventional nucleus breeding schemes.

Designing breeding schemes suitable for smallholder livestock production systems in developing regions has hitherto been a challenge. The suggested schemes either do not address farmers' breeding goals (centralized station-based nucleus schemes) or yield slow genetic progress (village-based schemes). A new breeding scheme that integrates the merits of previously suggested schemes has been designed for Menz sheep improvement in Ethiopia. It involves selection based on breeding values in nucleus flocks to produce elite rams, a one-time only provision of improved rams to villagers and a follow-up village-based selection to sustain genetic progress in village flocks. Here, we assessed whether conventional selection of breeding rams based on breeding values for production traits, which is the practice in station-based nucleus flocks, meets farmers' breeding objectives. We also elicited determinants of farmers' ram choice. Low but significant correlations were found between rankings of rams based on farmers' selection criteria, estimated breeding values (EBV) and body weight (BW). Appearance traits (such as color and horn) and meat production traits (BW and linear size traits) significantly determined farmers' breeding ram choice. The results imply that conventional selection criteria based solely on EBV for production traits do not address farmers' trait preferences fully, but only partially. Thus, a two-stage selection procedure involving selection on breeding values in nucleus centers followed by farmers' selection among top- ranking candidate rams is recommended. This approach accommodates farmers' preferences and speeds up genetic progress in village-based selection. The Menz sheep scheme could be applied elsewhere with similar situations to transform conventional station-based nucleus breeding activities into participatory breeding programs.

Trends and challenges in the effective and sustainable control of Haemonchus contortus infection in sheep. Review.

Haemonchosis, with its very wide distribution, has become a very important production constraint in sheep farms in tropical, subtropical and temperate regions worldwide. Various intrinsic and extrinsic factors determine the survival of Haemonchus contortus and hence the development of the disease in the animal. In general, control of gastrointestinal nematode infestation in sheep relies heavily on anthelmintic treatments. However, the indiscriminate use of these drugs has led to the widespread emergence of drug resistant strains of parasites, that has necessitated the development and use of various parasite control methods such as grazing management, biological agents and vaccines and the selection of resistant breeds of animals, with or without moderate use of anthelmintics. The ultimate goal of such control programs is to enhance productivity, while minimising risks regarding drug resistance and consumer and environmental concerns. This review attempts to highlight the different methods employed in the control of haemonchosis in sheep and the practical limitations associated with both control programs and the internal and external factors associated with the parasite and its microenvironment.

Experimental infection of Black Belly and INRA 401 straight and crossbred sheep with trichostrongyle nematode parasites.

Compared to INRA 401 lambs reared in France, Black Belly (BB) lambs reared in Guadeloupe (F.W.I.) were highly resistant to both primary and secondary experimental infection with Haemonchus contortus. To investigate this huge inter-breed difference, a nucleus flock of BB was constituted, and experiments were conducted to: (i) confirm this difference in lambs born in France, (ii) check whether it was similar for Trichostrongylus colubriformis and Teladorsagia circumcincta, and (iii) find out whether this difference was age-related. Forty BB lambs, 84 F1 lambs (BB siresxINRA 401 ewes) and 88 INRA 401 lambs born in two cohorts were used in an experimental design involving three host breeds, both genders and two age-groups (3.5- and 7-month-old when first infected). The limited availability of BB lambs made the study incomplete. Infection consisted of the administration of two doses of 10,000 infective larvae of one of the nematode species, separated by an anthelmintic treatment and an interval of 1 week before the second dose was administered. Fecal egg counts (FECs) were done on Days 28 and 35 after each infection; ewe lambs of the INRA 401 and F1 breeds were necropsied, the worm burden was established, the length of the female worms measured and the eggs in utero counted. For H. contortus and T. colubriformis, the FEC was lower in the BB than in the INRA 401 lambs, and the FEC found for the F1 lambs was intermediate. For T. circumcincta, only data for the F1 and INRA 401 lambs were available, and the FECs for these breeds were the same. In all three breeds, the FEC determined after the second dose was significantly lower than that found after the first dose in the ewe lambs, but not in the ram lambs. Infecting the lambs when they were 7- instead of 3.5-month-old significantly lowered egg excretion of both parasites in the F1 (P<0.0001), but not the INRA 401 lambs. Worm numbers in the F1 and in the INRA 401 ewe lambs confirmed the FEC data, many F1 lambs being free of T. colubriformis. The H. contortus female worms were shorter and had fewer eggs in utero in the F1 than in the INRA 401 lambs. A higher proportion of T. circumcincta was at the fourth larval stage in the F1 lambs. In conclusion, the BB breed is much more resistant than INRA 401 to H. contortus, with the F1 lambs being more like the BBs after the second dose. This difference was also found for T. colubriformis and, to a lesser extent, for T. circumcincta.