Abstract
PurposeIn the fight against anthelmintic resistance, targeted selective treatments (TSTs), where only a small percentage of a flock receives treatment, have become increasingly popular. Overall, implementation of such treatments can be based on various parameters including Body condition score (BCS). As infection with non-bloodsucking nematodes, frequently encountered on sheep farms in the central Mediterranean basin, commonly causes bodyweight reduction, the aim of this research is to evaluate the effectiveness of BCS as a parameter for the implementation of TSTs in lactating dairy sheep with subclinical gastrointestinal nematode (GIN) infections from the island of Sardinia, Italy.MethodsFaecal samples from 1012 ewes divided into 2 groups (third and fifth month of lactation) were collected and their BCS recorded. Faecal egg counts and coprocultures were performed for the assessment of the GIN burden and identification of present species.ResultsAn overall GIN prevalence of 85.4% with a mean eggs per gram (EPG) of faeces of 210.1 ± 347.3 was found. Teladorsagia spp. and Trichostrongylus spp. were the GIN genera most identified. Overall, animals with the lowest BCS had the highest EPG values and a negative correlation (r = − 0.163) between the EPG values and BCS of the studied animals was found, which was most significant for older sheep.ConclusionThis research confirmed BCSs and EPG values for GIN in sheep to be negatively correlated, particularly in older ewes. Application of TSTs for lactating sheep with a BCS < 2.25, especially to older ewes, could be beneficial in case of subclinical GIN infections, although further studies are needed to work out precise recommendation.
Highlights
Gastrointestinal nematodes (GIN) represent a major health and zootechnical concern in small ruminant farming and may have significant negative effects on grazing dairy sheep [1,2,3,4,5].Anthelmintic interventions are still the most frequently applied control measures against GIN infections [6] and in most cases, implementation of such treatments is done in a somewhat irrational fashion
targeted selective treatments (TSTs) programs can be based on various parameters such as: Faecal Egg Counts (FEC), Hematocrit (HCT) values, direct assessments of the degree of anemia through examination of the conjunctival mucosa, faecal consistency score, milk production, weight loss and Body condition score (BCS) [2, 13, 18,19,20,21,22,23]
In the lights of this, the aim of this study is to evaluate the effectiveness of BCS as a parameter for the implementation of TSTs in dairy sheep farms in the central Mediterranean basin where subclinical GIN infections with T. circumcincta, Trichostrongylus spp. and H. contortus are common
Summary
Gastrointestinal nematodes (GIN) represent a major health and zootechnical concern in small ruminant farming and may have significant negative effects on grazing dairy sheep [1,2,3,4,5].Anthelmintic interventions are still the most frequently applied control measures against GIN infections [6] and in most cases, implementation of such treatments is done in a somewhat irrational fashion. TSTs entail solely the treatment of the most affected animals (usually a small percentage of the flock) [13, 14], leaving most of the animals in the flock untreated, ensuring the presence of larvae in refugia on pastures [15, 16]. FEC, employed with different threshold values, is an effective parameter but challenging when applied in large flocks [22] since egg excretion is dependent on the physiological situation of treated animals (e.g. after lambing, related to the post-parturient rise) and nematode species present (e.g. Haemonchus contortus females are fecund, leading to high FECs even when worm burdens are low)
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