Abstract
The parasitic resistance in Sri Lankan indigenous (SLI) goats is getting gradually replaced owing to unsystematic crossbreeding. This study was conducted to identify phenotypic resistance to haemonchosis of between and within genotypes in SLI goats and their Jamnapari crossbreds (JCB) and to identify level of phenotypic resistance to gastrointestinal strongyle parasitism exists in SLI and JCB at field. The study consists of an artificial challenge (40 goats) and a field trial (521 goats). In artificial challenge, two genotypes have responded to parasitism differently. Significant effects of measurement time (MT) and MT×genotype interaction were reported for log transformed faecal egg counts (FEC). Effect of MT was significant for least square mean packed cell volume (PCV). Peak FEC was reported at day-35 for both SLI and JCB; whereas, the lowest PCV values were observed for SLI and JCB at 28th and 42nd day respectively. When animals were grouped based on the highest recorded FEC, a majority of SLI (55%) was occurred under the category intermediate (I) while a majority of JCB (78%) was in the category high (H). Category low (L) was represented only by SLI (20%). Significant effects of group, MT and group × MT were observed on ln FEC in both genotypes. In both SLI-H and JCB-H, the highest FEC was reported at day-35. SLI-I and SLI-H were recovering from parasitism at the latter part of experiment whereas JCB-I and JCB-H were continuing with parasitism. In the field trial, both genotypes occurred in high frequency in group L. Hence, phenotypically SLI were more resistant to haemonchosis than JCB. There is a high within genotype variability for phenotypic parasitic resistance in both genotypes. Thus, this information is important in identifying genomic parasitic resistance in both genotypes.