Genetic parameters involving subjective Famacha© scores and faecal worm egg counts on two farms in the Mediterranean region of South Africa S.W.P. Cloete, Z. Mpetile & K. Dzama Elsenburg and Stellenbosch University

Introduction Drenches as the first line of defense of gastro-intestinal parasites has become unsustainable Host resistance important component in almost all integrated pest management (IPM) programmes Selection for low faecal worm egg counts (FWEC) benefited host resistance to gastro-intestinal helminths Selection reduced the contamination of pastures by worm eggs Resulted in less drenching and economic gains FWEC routinely recorded in many formal evaluation schemes

Introduction FWEC may not always reflect the parasite burden of animals Infrastructure to conduct FWEC not always available or affordable: Rural areas Developing countries Need alternative strategies FAMACHA© system proposed as an alternative Involves subjective scores of the conjunctivae of the eye of sheep with high burdens of haemotophageous nematodes Allows sheep farmers to treat specific sheep, in contrast to treating all sheep present

FAMACHA© scoring system

Introduction Principle not applicable when non-haemotophageous nematodes form the bulk of the gastro-intestinal parasite challenge Eye scores supplemented with condition scores and dag scores Scores were practical for commercial and resource-poor communal farmers in South Africa Also applied elsewhere in the world Not assessed under Mediterranean conditions, where species such as Teladorsagia, Trichostrongylus and Nematodirus predominate FAMACHA© scores and FWEC thus assessed on two properties in the Mediterranean region of South Africa

Locations Elsenburg: North of Stellenbosch Dryland lucerne and kikuyu pastures, oat fodder crops Occasionally irrigated lucerne and kikuyu pastures Rainfall 625 mm per annum mostly from April – September (78%) Lambs born in March – April, tested in November Tygerhoek: Near Riviersonderend Dryland lucerne pastures and oat fodder crops Rainfall of 425 mm per annum mostly from April – September (62%) Lambs born in March – April, tested in August of the next year

Material and Methods (Animals and records) Data: Elsenburg (1701 – 1815 Dormer and SA Mutton Merino lambs born from 2007 – 2014) Tygerhoek (1531 – 2219 Merino hoggets born from 2006 – 2012) Traits recorded and measured: Subjective: Nasal discharge (excluded, little variation) Eye score Body condition on two sites: Midrib Loin Dags Objective: FWEC, counted at a sensitivity of 100 eggs/gram wet faeces Skewed, transformed to natural logs + 100

Statistical Analysis Data analysed with 5-trait threshold-normal animal models with animal as single random effect Fixed effects: Contemporary group (birth year x breed or selection line x sex) Age of dam (2 – 6+ years) Birth type (single or multiple) Data were analysed by THRGIBB1SF90 software, Post Gibbs analysis with POSTGIBBSF90 Single chains of 250000 cycles were run First 50000 cycles used as the burn-in period Every 10th subsequent sample stored to derive posterior means, posterior standard deviations and 95% highest posterior density (HPD) confidence intervals

Results – Samples for dag score at Elsenburg

Posterior distributions for additive effects at Elsenburg

Descriptive statistics – Elsenburg Trait Number Mean ± SD Range Eye score 1815 1.94 ± 0.89 1 – 4 Fat score rib 3.27 ± 0.73 1 – 5 Fat score rump 3.09 ± 0.73 Dag score 1813 2.08 ± 1.14 FWEC 1701 6.86 ± 1.24 4.6 – 10.4

Descriptive statistics – Tygerhoek Trait Number Mean ± SD Range Eye score 2093 1.56 ± 0.59 1 – 4 Fat score rib 1531 3.07 ± 0.55 1 – 5 Fat score rump 1533 2.92 ± 0.67 Dag score 2207 2.17 ± 1.13 FWEC 2219 5.65 ± 1.09 4.6 – 10.4

Results – Genetic parameters at Elsenburg Phenotypic variance (σ2p), heritability (h2), genetic correlations (rG) and phenotypic correlations (rP) Trait Eye score Fat rib Fat rump Dag score FWEC ²P 0.237 0.383 0.394 1.612 1.077 h2 (in bold on diagonal), rG (above diagonal) and rE (below diagonal) 0.13±0.05 -0.45±0.22 -0.71±0.27 0.06±0.22 0.66±0.27 -0.43±0.06 0.12±0.04 0.92±0.23 0.12±0.18 -0.19±0.21 -0.44±0.06 0.66±0.07 0.17±0.05 0.04±0.18 -0.25±0.22 0.16±0.07 -0.17±0.06 -0.18±0.06 0.31±0.07 -0.19±0.23 -0.03±0.06 -0.10±0.05 -0.09±0.05

Results – Genetic parameters at Tygerhoek Phenotypic variance (σ2p), heritability (h2), genetic correlations (rG) and phenotypic correlations (rP) Trait Eye score Fat rib Fat rump Dag score FWEC ²P 0.294 0.463 0.325 1.670 1.040 h2 (in bold on diagonal), rG (above diagonal) and rE (below diagonal) 0.12±0.05 -0.82±0.23 -0.50±0.18 0.25±0.22 -0.29±0.21 -0.26±0.07 0.38±0.13 0.80±0.18 -0.14±0.27 0.01±0.22 -0.26±0.06 0.65±0.06 0.30±0.11 -0.15±0.22 0.23±0.23 0.06±0.06 -0.10±0.06 -0.07±0.07 0.31±0.08 0.27±0.26 0.02±0.05 -0.10±0.05 -0.15±0.06 -0.07±0.06 0.14±0.05

Conclusions All traits were heritable and variable and should respond to directed selection Genetic correlations suggested that: Animals with higher eye scores were leaner Fat score on the rib and rump are largely similar traits Eye score at Elsenburg were favourably correlated to FWEC Dag score, although highly heritable, were not associated with any other trait Favourable genetic correlation between eye score and FWEC possibly associated with nematode species distribution Haemonchus more prevalent Dag score of significance in controlling breech blowfly strike The results support further studies on the FAMACHA© system under low-input small stock operations

Schalk Cloete Directorate Animal Sciences: Elsenburg 021 8085230 086 5084391 schalkc@elsenburg.com