Sky Journal of Agricultural Research Vol. 3(2), pp. 025-030, February, 2014 Available online http://www.skyjournals.org/sjar ISSN 2315-8751 2014 Sky Journals Full Length Research Effect of coat colour, ecotype, location and sex on hair density of West African Dwarf (WAD) goats in Northern Ghana NAANDAM, Jakper* and ASSAN, Ishmael Kojo Department of Animal Science, Faculty of Agriculture, University for Development Studies, P. O. Box TL 1882, Tamale, Ghana. Accepted 5 February, 2014 Trends in global warming call for identification and development of heat tolerant goats. Hair density as a defining adaptive attribute would seem to assume some critical importance. A study was carried out in Bongo and Tamale main abattoirs to establish whether there were any hair density variations in local goats belonging to different geographical areas. Twenty four (24) West African Dwarf (WAD) goats (12 from each region) were used for the experiment. Parameters like age, coat colour and weight were noted directly from the animals before slaughter. For hair density determination, six point four five square centimeters (a square inch) was randomly selected on the flayed skins of the WAD goats, shaved and the number of hair follicles was obtained using a colony counter. Number of hair follicles per square inch at each location was used as the hair density. The results showed significant effects for sex (p < 0.001), ecotype (p < 0.001) position of hair on the body i.e. dorsal or ventral (p< 0.001), on hair density. In addition, age significantly (p < 0.001) affected hair density while coat colour had no effect on hair density (p > 0.05) possibly suggesting that the Black and Brown colours used in present study may be functionally closer in their physiological tasks. Key words: Ecotype, hair density, hair follicles, heat tolerant goats, WAD goats. INTRODUCTION Livestock rearing plays a major role as a safety net that enables households to get quick income to settle urgent financial needs such as buying food and farm inputs, settling hospital bills, paying school fees, expenses for funeral and marriage (Dzoagbe et al., 2007). Goats tend to tolerate heat better than sheep. Goats with loose skin and floppy ears may be more heat tolerant than other goats. Angora goats have a decreased ability to respond to heat stress as compared to sheep and other breeds of goats. Dark-colored animals are more susceptible to heat stress, while light-colored animals may be proned to sunburn. These observations were made by Schoenian (2010). Schoenian (2010) further stated that horned *Corresponding author: jaknaan@yahoo.com. Tel.:+233244895504/+233205162657. animals dissipate heat better than polled (or disbudded) animals. Young animals are more susceptible to heat stress than older animals. In fact, any animal with a poor nutritional status or compromised immunity will be more susceptible to environmental extremes this author wrote. Tropical areas are endowed with a wide variety of indigenous small ruminant breeds that have evolved to adapt to the prevailing harsh environmental conditions and traditional husbandry systems (Baker and Rege, 1994). This adaptation to the harsh environmental condition may be linked to the hair density of small ruminants, as hair is known to have some insulating role. According to Baton et al. (2004) the coat acts as a mat to physically prevent the sun rays from reaching the animal s body. Also the long hair serves as an insulator from the heat, providing a hair buffer zone between the outer environment and the animal s body.
26 Sky. J. Agric. Res. Given the current trend in global warming, goats that can withstand rising environmental temperatures will become critical. One way to have a well adapted critical mass of goats, is through focusing on the production and maintenance of goats that are heat tolerant in terms of hair density on their skin. Bongo district is a bit warmer than Tamale metropolis and over the past 40 years temperatures in Bongo have increased by about 1 C (Obeng, 2005). Consequently this study set out to examine hair density variations, if any, as they relate to these two ecotypes and other factors in the local WAD goats. MATERIALS AND METHODS Study area The study was carried out at the Tamale and Bongo abattoirs. Tamale main abattoir is situated at Shishegu in Tamale metropolis, in northern region of the Guinea zone. It is located at 9 24 l north of the equator, 0 50 l west of the Greenwich meridian, and 120 m above sea level. Temperature ranges from 9 C to 38 C. Bongo abattoir on the other hand, is located in Bongo dstrict in Upper East region on the fringes of the Sudan Savannah. It lies between latitudes 10 o 54 and 28 and 0 o 48 and 29 North. Experimental animals Twenty four (24) WAD goats were considered for the experiment. WAD goats were identified according to characteristics presented by Adedeji et al. (2006). Additionally, Expert technical assistance information was obtained from the Kintampo goat breeding station in Ghana on height of WAD goats at withers (under 50 cm) and weight (18-25 kg). Out of the 24 animals, 12 animals from Bongo abattoir comprised 6 young animals (3 males and 3 females) with different weights and ages and of two colours (brown and black). The remaining 6 were adult animals (3 males and 3 females), also with varied weights, ages and of the same colours as in the young ones. Similar data had been taken from the Tamale abattoir. Parameters considered Parameters considered were colour (by observation), weight (using a spring balance) and age (by dentition). Hair follicle density was obtained after slaughtering. Processing and preservation of skin After animals were killed through ritualistic or religious slaughtering, the flayed skin which naturally contains bacteria on the death of the goat multiply that causes putrefaction of the skin. In hot humid conditions, this process of rottening will quickly spoil the skin (Peacock, 1996). The fresh skin was cleaned using tap water then spread on a concrete floor, inner side facing upwards and granulated salt applied on every part. The salt removes water from the skin and stops bacterial growth that caused rottening (Steele, 1996). The skins were folded into a basket and transported to the laboratory for analysis. Hair follicle determination By random sampling, six (6) sections were obtained from each skin (2 sections from the dorsal part and 4 sections from both the right and left ventral parts of the skin). With the aid of a plastic meter rule and a marker, six point four five square centimeters (i.e. a square inch) was measured from each of the above stated sections and the hair shorn with a blade to enhance clearer view of the hair follicles. The colony counter gives a bright background enhancing easy count of the hair follicles (Plate I). Statistical analysis Data were analysed by regression method using generalized linear model in Genstat (3.0 edition) Results are presented in bar charts and tables. RESULTS Effects of sex, age, colour and ecological zone on mean hair density Figure 1 shows the effect of sex on the hair density for WAD goats at various stages of developments. Generally female goats had higher mean hair density (P > 0.001) than males in absolute terms for particular age groups. The variation in hair densities of WAD goats from Bongo in the Upper East region and Tamale in the Northern region of Ghana is depicted in Figure 2. Goats from the Northern region had higher mean hair density (P > 0.001) than those from Upper East region. Goats with brown coat colour appeared to have higher mean hair density than those with black coat colour in absolute terms but the difference was not significant (P > 0.05) (Table 2 and Figure 3). Regression analysis The genstat output for the regression analyses for number of groups of fitted terms were as follows:
Mean Hair density (No. per 6.45cm sq.) Jakper and Kojo 27 Plate I. Counting number of hair follicles on skin with the help of a colony counter. 600 400 200 0 Young females Young males Adult females Adult males sex Figure 1. Effect of sex on mean hair densities of West African Dwarf (WAD) goats at different stages of growth. Figure 2. Effect of ecological zone on mean hair density of West African Dwarf goats. Response variate: hair density Fitted terms: constant + eco-zone + sex + colour + age - years + location Summary of analysis Table 1 show the analysis of variance for the fitted terms
28 Sky. J. Agric. Res. 380 375 370 Mean Hair density (No.per 6.45 cm sq) 365 360 355 350 Black Coat Colour Brown Figure 3. Effect of coat colour on hair densities of WAD goats. Table 1. Anova table for fitted terms; eco-zone, sex, colour, age and location. Degrees of Sum of squares Mean square F.calculated Probabilty freedom Regression 9 255154. 28350.5 48.88 <.001 Residual 134 77726. 580.0 Total 143 332880. 2327.8 Percentage variance accounted for 75.1. Table 2. Standard error, t statistic and probability estimates for fitted parameters. Parameters Maximum likelihood estimates Standard Error of estimated parameter t statistic Significance (tpr) Constant 319.35 5.49 58.19 <.001 Eco-zone 2 19.08 4.44 4.30 <.001 Sex 2 27.48 4.33 6.34 <.001 Colour 2 8.52 4.53 1.88 0.062 Age -years 2.5 28.9 11.0 2.63 0.010 Age-years 3.5 91.0 10.9 8.38 <.001 Age -years 4 72.18 4.44 16.27 <.001 Age -years 4.5 50.4 10.9 4.64 <.001 Age -years 5 56.7 10.7 5.29 <.001 Location 2-34.69 4.02-8.63 <.001 eco-zone, sex, colour, age (years) and location. The fitted terms were highly significant (p < 0.001) with an R 2 of 75.1%. The estimates of parameters indicated very high significant levels (P < 0.001) for all items fitted in the regression except for colour which was not significant (P > 0.05) (Table 2). R 2 increased to 86% when eco-zone was dropped from the fitted terms. Notwithstanding, it demonstrated that the accuracy of predicting hair density could be improved if a stepwise regression was carried out. DISCUSSION Effects of sex, age, colour, eco- zone and location on the body on mean hair density As alluded to earlier Schoenian (2010) noted that darkcolored animals are more susceptible to heat stress, while light-colored animals may be prone to sunburn. This assertion about coat colour adaptability is buttressed by the fact that hair works as a temperature regulator in association with muscles in the skin. When the outside
Jakper and Kojo 29 temperature is cold, these muscles pull the hair strands upright, creating pockets that trap air which provides a warm, insulating layer next to the skin. In case the temperature outside is warm, the muscles relax and the hair becomes flattened against the body, releasing the trapped air. Low hair density should thus be a good adaptation for extreme temperatures since more air will be trapped for insulatory purposes during cold weather while the same should give enough room for better flattening of the hair during warm weather. This should translate into less air being trapped on the skin and consequently a resultant lesser heating effect of trapped air. Thus the mean hair density for eco-zone (Bongo vs Tamale) being significantly different (P < 0.001) as illustrated in Figure 2 could probably for explained by the fore-going. Obeng (2005) showed that temperatures in Bongo district over the past 40 years have increased by about 1 o C during that period compared to the overall for northern Ghana, supporting the hypothesis that the less hair goats have in Bongo, the better they would be at containing the increased temperature in the environment. Jordan (1999) noted that, big Angora goats produce more kids and more hair. So, there may be a relationship between reproductive activities and hair density. This relationship and other genetic differences may be postulated in present study to explain why females had a higher mean hair density than males (Figure 1 and Table 2). With age, however, Wikipedia, (2008) has noted that the anagen is the active growth phase of hair follicles where root of the hair are dividing rapidly in humans, adding to the hair shaft. The amount of time the hair follicle stays in the anagen phase is genetically determined. If hair growth in goats is assumed to follow this pattern, then it is easily explained why adults had a higher mean hair density (Figure 1 and Table 2) than young ones. At the end of the anagen phase, an unknown signal causes the follicle to go into the catagen phase the authors wrote. Sponenberg (2004) explained that many different alleles occur within the Agouti locus of goats, however all of the caprine Agouti locus patterns are characterized by symmetrical arrangements of eumelanic and phaeomelanic areas. In goats, the eumelanic areas are usually black, although can be brown when the genotype at other loci modifies black to brown, suggesting that the black and brown colour may be very close in their attributes and thus explaining the possible insignificant difference that was observed in this study between the two colours. Whereas Siddiqua and Amin (2009) observed some significant effect (p < 0.001) in colour on the hair density of goats, their work involved black and white goats, which is to be expected as black is a distant variant of white. With reference to location of the hair on the body, the study found significant differences (P < 0.00) within the same coat colour groups. Higher hair density was found on dorsal portion compared to the ventral, which again could be an adaptive feature of insulating the dorsal portion better than the ventral against inclement weather, since animals are exposed to the environment more by via those portions. The regression equation suggested that it may be possible to predict hair density using the fitted terms but the coefficient of determination R 2 could only account for 75% of the total variation in the dependent variable. Conclusion West African Dwarf (WAD) goats found in the Northern region of Ghana had higher hair density than those found in the Upper East region of Ghana (Bongo). Also, female WAD goats had more hair per unit area than males, both for the young and adult goats. Brown and black coat colours appear to have similar effect on hair density. Further studies recommended to be carried out using more animals should include animals in the forest zone to get a better effect of climate. Molecular basis of hair density should be explored in future research. REFERENCES Adedeji TA, Ojedapo LO, Adedeji OS, Aderogba TA, Abdullah AR (2006). Characterization of Traditionally Reared West African Dwarf Goats (Wad) in the Derived Savannah Zone of Nigeria. J. of Animal and Vet. Advan., 5: 686-688. Baker RL, Rege JEO (1994). Genetic resistance to diseases and other stresses in improvement of ruminant livestock in the tropics. In: Proceedings of the fifth World congress on Genetics Applied to livestock Production, Vol. 20, University of Guelph, Ontario, Canada, 7-12 August, 1994, pp. 405-410. Baton R, Louisiana SV, Roussel JD (2004). Heat Stress. In: National Goat Hand book. National Agriculture Database Laboratory. http.// outlands. tripod. com/ farm / national- goat- handbook. pdf. Date Retrieved on 20/ 03/ 12. Dzoagbe GSK, Ansah T, Gong AS (2007). Women in livestock production in the West Gonja District of Northern Region: the Savanna farmer publication of church Development projects (ACDEP). A magazine on sustainable Agriculture, July December, (2007), 8(2): 12-14. Jordan RM (1999). Angora goats in the Midwest. Extension Animal Specialist, University of Minnesota. Obeng FK (2005). Things are Hard For Us, But We See A Way Out Of Them. Impact of Climate Variability On Geographical and Occupational Mobility and The Effect of Mobility On Social Organization in Farming Communities in North _Eastern Ghana. Amsterdam Institute of Metropolitan and International Development Studies (AMIDSt), University of Amsterdam, The Netherlands. Peacock C (1996). Improving Goat Production in the Tropics. A manual for development workers.an Oxfam / Farm- Africa Publication. pp. 1-7. Schoenian S (2010). Small Ruminant Info Sheet, Sheep and goats.com, Heat stress in sheep and goats, University of Maryland Extension. Available at http://www.sheepandgoat.com/articles/heatstress.html. Retrieved 2/2/14 Siddiqua SA, Amin MR (2009). Characterization and performance evaluation of White, Silver Bezoar and Black type of Black Bengal goat in north western region of Bangladesh. J. Bang. Agric. Univ., 7(2): 305-315. Sponenberg DP (2004). Genetics of Goat colour. Virginia-Maryland Regional College of Veterinary Medicine. Virginia Polytechnic Institute and State University Blacksburg, VA 24061 USA.
30 Sky. J. Agric. Res. Steele M (1996). The Tropical Agriculturist Goats. Macmillan Education Ltd, London. pp. 1-8, 9-21, 122-131. Wikipedia (2008). Hair follicle. Wikimedia Foundation, Inc. http://en.wikipedia.org/wiki/hair_follicle. Retrieved 16/3/2013.