Abdullah Sani, Rehana

Panandam, Jothi Malar

Universiti Putra Malaysia Institutional Repository

R&D at UPM: Research SnapshotsRehana Abdullah Sani and Jothi PanandamQail.I~~Selection of Sheep Resistant to WormsGenetically determined differences in the resistance of animals to gastro-intestinal nematode infections arewell recognised and offer an alternative control procedure. The objective of this study was to select sheepfor resistance to Haemonchus contortus and to investigate the inheritance of that resistance in their off-springs.The breed of sheep used was Santa Ines belonging to Ladang Pembiakan Bebiri, Jabatan PerkhidmatanHaiwan Malaysia at Gajah Mati, Kedah. A total of 57 animals were selected from a population of 123 threemonth-old lambs from tWI}flocks. Animals were categorised based on their faecal egg counts (FEC) fol-lowing naturally acquired infection. Animals were ranked according to their individual FECs for each sam-pling date. At the end of the field study cumulative ranking was obtained. High responder lambs (HR) weredeemed to be those with the lowest cumulative FEC ranking (mean epg < 2725) or those lambs which, re-sponded well to strongyle infection. Animals with highest overall ranking (mean epg > 3675) were classi-fied as Low Responders (LR) which were more susceptible to strongyle infection. The selected animalswere treated to remove the field infection and subsequently infected with larvae of Haemonchus contortusto study their response to experimental infection. Based on their responses to the field as well as experi-mental infections, the animals were classified as HR and LR. Upon attaining sexual maturity HR maleswere mated with HR females and LR males were mated with LR females. The offsprings of these matings,at 3-4 months old, were challenged with infective larvae to confirm their responder status and hence theinheritance of resistance. The lambs were also weighed pre-infection and post-infection for a period of 12weeks. FECs of HR animals at pasture was significantly (p<O.OO I) lower than that of LR animals. FECs ofHR animals was also significantly less than the herd average.Following challenge infection the differences in FEC between the HR and LR animals were signifi-cantly different post-infection.The FECs of the pedigrees showed that sires and ewes who are high responders produced offspringswho have similarly low FECs. Conversely parents who are low responders produced lambs with highFECs.In the present study there was no significant difference in body weights of lambs between the responderanimals. Genetically resistant lambs had no significant growth rate advantage over their susceptible coun-terparts when both genotypes grazed together under the same nematode challenge.The appearance of a trend of higher FEC among the LR animals when compared to HR animals suggestthat it is possible to segregate animals into high and low responders based on FECs and that FEC can beused as an indicator for resistance. This study shows that it is possible to select and breed Haemonchuscontortus resistant lines of Santa Ines sheep. Resistant lines of sheep are of economic interest in areaswhere production losses due to helminthosis are severe.Reader EnquiryFaculty of Veterinary MedicineUniversiti Putra Malaysia43400 UPM, Serdang, SelangorMalaysiaTel: +603 89468289E-mail: rehana@vet.upm.edu.my78

Selection of sheep resistant to worms

http://psasir.upm.edu.my/47377/1/Selection%20of%20Sheep%20Resistant%20to%20Worms.pdf

Selection of sheep resistant to worms

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Universiti Putra Malaysia Institutional Repository