Prevalence of coat colour phenotypes and its influence on mange infestation of West African Dwarf goat

Abstract

Prevalence of coat colour phenotypes and its influence on sarcoptic mange infestation of West African Dwarf (WAD) goats reared extensively by subsistence farmers in South-west Nigeria was investigated from March to October, 2011. The total number of goats randomly sampled from different villages within the same ecological zone were 11,772 consisting of 8,384 females and 3,388 males of different ages. Three basic coat colours were identified, namely black, brown and white accounting for 24%, 9.22% and 4.10% respectively. They probably constituted the underlying base for the caramel (bargerface), agouti and spotting patterns, giving rise to twenty combinations which accounted for the remaining 62.68% in the breed. The distribution pattern was similar for males and females. The number of goats randomly sampled and clinically inspected for presence of mange lesions on different parts of the body was 7,902. Standard parasitological procedure used to confirm the presence of mange mite from skin scrapings revealed that 42 goats (0.53%) were infested by Sarcoptes scabiei var. caprae. Infested cases were ranked according to severity of infestation as localized and mild (1), localized and moderate (2), localized and severe (3), generalized and mild (4), generalized and moderate (5) and generalized and severe (6) based on information from literature. Only five colour phenotypes (black, black with white marking, bargerface, white/brown mixed and white) were infested by mange. Black goats predominated (50%) the infested group, followed by those with black with white marking (23.81%), while white goats were least (4.76%). Least-squares analysis of variance showed that ranked estimate was significantly affected by coat colour (P<0.05). Goats with black and black with white marking were most affected with generalized and mild infestation, ranking 3.97±0.34 and 4.31±0.50, respectively (P>0.05). Those with bargerface and mixture of brown/white had similar (P>0.05) estimates (2.60±0.66 vs 3.52±0.93) while white goats were least affected with localized and mild infestation (0.88±0.18). The effect of age was significant (P<0.01) while sex was not significant. Animals less than one year were more affected with generalized and mild infestation, ranking 4.10 ± 0.58 compared with older animals (>1 year) that ranked 2.23 ± 0.55 with localized and moderate infestation. It is concluded that black goats were most prevalent and more susceptible to mange infestation while white goats were least affected. Selection in favour of other colour combinations that were not infested could further control prevalence of mange in the region.

Key words: Goat, coat colour distribution, influence on mange infestation