Faecal Egg Count (FEC) is generally considered a simple but effective parameter for estimating resistance to strongylids, due to its phenotypic relationship to the total number of parasites present in the animal. Nevertheless, also haematological indicators have been shown to be useful in measuring gastro-intestinal nematode resistance in sheep, such as Packed Cell Volume (PCV), number of leukocytes, proportion of eosinophils and plasma albumin. The study was conducted in a single herd of Appenninica sheep situated in Tuscany (Italy) with the aim of studying the relationship among parasitic load of gastro-intestinal Strongylids and haematological parameters. Faecal samples from 54 sheep were collected in four different withdrawals (April, May, September and November 2004) and analysed in order to determine parasite EPG (Eggs Per Gram), using the McMaster technique. At the same time as the faecal samples, blood samples were also collected in order to determine PCV, total proteins, complement proteins, plasma albumin, erythrocytes and eosinophils. Considering the low infection level in spring (April and May), it was believed that animals with a positive EPG in this season could already be considered “not resistant”, although a limited infection (EPG<200) might serve as an index of host’s capacity to keep the parasite population under control. Consequently, we defined as “resistant group” (RG) the subjects with an average value in the spring sample equal to zero EPG, “intermediate resistant group” (IRG) the subjects with an average value under 200 EPG and “not resistant group” (NRG) the animals with an average value over 200 EPG. NRG subjects always showed lower values of PCV (an indicator of anaemia) than the other groups. In September, NRG subjects also showed significantly lower values of eosinophils (3.28%) compared to the other groups (6.54 and 6.20%, respectively, for IRG and RG, P<0.01) and higher values of complement (20.06 vs. 12.61 and 12.77, respectively, for IRG and RG, P<0.05). On the contrary, in November, NRG subjects showed lower values of complement (7.78) than the other groups (19.00 and 15.23, respectively, for IRG and IR, P<0.01).

The genetic resistance to gastro-intestinal strongylids in Appenninica sheep: Relationship among parasitical load and haematological parameters

CECCHI, FRANCESCA;CIAMPOLINI, ROBERTA;MACCHIONI, FABIO;
2007

Abstract

Faecal Egg Count (FEC) is generally considered a simple but effective parameter for estimating resistance to strongylids, due to its phenotypic relationship to the total number of parasites present in the animal. Nevertheless, also haematological indicators have been shown to be useful in measuring gastro-intestinal nematode resistance in sheep, such as Packed Cell Volume (PCV), number of leukocytes, proportion of eosinophils and plasma albumin. The study was conducted in a single herd of Appenninica sheep situated in Tuscany (Italy) with the aim of studying the relationship among parasitic load of gastro-intestinal Strongylids and haematological parameters. Faecal samples from 54 sheep were collected in four different withdrawals (April, May, September and November 2004) and analysed in order to determine parasite EPG (Eggs Per Gram), using the McMaster technique. At the same time as the faecal samples, blood samples were also collected in order to determine PCV, total proteins, complement proteins, plasma albumin, erythrocytes and eosinophils. Considering the low infection level in spring (April and May), it was believed that animals with a positive EPG in this season could already be considered “not resistant”, although a limited infection (EPG<200) might serve as an index of host’s capacity to keep the parasite population under control. Consequently, we defined as “resistant group” (RG) the subjects with an average value in the spring sample equal to zero EPG, “intermediate resistant group” (IRG) the subjects with an average value under 200 EPG and “not resistant group” (NRG) the animals with an average value over 200 EPG. NRG subjects always showed lower values of PCV (an indicator of anaemia) than the other groups. In September, NRG subjects also showed significantly lower values of eosinophils (3.28%) compared to the other groups (6.54 and 6.20%, respectively, for IRG and RG, P<0.01) and higher values of complement (20.06 vs. 12.61 and 12.77, respectively, for IRG and RG, P<0.05). On the contrary, in November, NRG subjects showed lower values of complement (7.78) than the other groups (19.00 and 15.23, respectively, for IRG and IR, P<0.01).
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/115884
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