
Research Article


Relationship Between Annual Rainfall Oscillations and Mohair Production in Lesotho Between 1935 and 1996


J.W. Ng`ambi,
D. Norris
and
C.A. Mbajiorgu



ABSTRACT

This study was conducted to determine trends in annual rainfall oscillations and mohair production in Lesotho between 1935 and 1996. An exponential regression equation of the form LnY = LnA + bx was used to estimate trends. Between 1935 and 1965 Angora goat numbers, mohair production and mohair yield per goat increased (p<0.01) at annual rates of 1.1, 1.9 and 1.1%, respectively. During years of independence (19661996) annual goat numbers remained, largely, stagnant (p>0.05) at around one million animals. Mohair yield per goat declined (p<0.01) at an annual rate of 1.2% to around 0.85 kg in 1996. Similarly, mohair production declined (p<0.01) at an annual rate of 1.2% to 970,000 kg in 1996. A longterm (19351996) annual rainfall mean of 700 mm was calculated. There were recurrent wet (rainfall above longterm mean) and dry (rainfall below longterm mean) years. However, no clear alternate rainfall oscillations of wet and dry years were observed. It was, thus, difficult to predict years of drought (rainfall below longterm mean) from alternate annual rainfall oscillations. A positive but nonsignificant (p>0.05) relationship between annual mohair yield per goat (kg) and rainfall (mm) was observed. Policy implications of the results on drought preparedness are discussed.





INTRODUCTION The agricultural sector is the largest single sector in the economy of Lesotho. It contributes to income and employment for >85% of the population (Eckert and Nobe, 1982; Bureau of Statistics, 2000). In 2005, agriculture contributed 23.9% of the Gross National Product. Seventy five percent of this contribution came from the livestock sector (Bureau of Statistics, 2005). Angora goats have played an important role in the economy of Lesotho for a long time. They provide an important source of cash income through the sale of their mohair, their meat or the animals themselves. In the food system, Angora goats provide meat which is a high quality protein food for Basotho people (Phororo, 1979; Lawry, 1986; Hunter, 1987). Mohair sales contribute between 14 and 20% of the total income generated by the livestock sector in Lesotho (Hunter, 1987; Bureau of Statistics, 2005). In 2000 more than R16 million was realized from mohair sales (Bureau of Statistics, 2001). However, most studies indicate that annual mohair production, mohair yield per goat and Angora goat numbers have declined since independence in 1966 (Uys, 1977; Wyeth et al., 1983; Hunter, 1987; Belete et al., 1994). These studies listed poor nutrition as being the most important cause of low annual mohair production, mohair yield per goat and Angora goat numbers. Communal rangelands play an important role in the livestock production systems in Lesotho (Phororo, 1979). Thus, Angora goats depend, mainly, on natural pastures in these rangelands for their nutritional requirements. These natural pastures, in turn, depend on rainfall for their growth. Reduced amounts of rainfall or droughts have a negative effect on pasture growth, resulting in less food for the animals and hence low mohair yield per goat (Hunter, 1987). Thus, each time there is drought farmers in Lesotho lose a lot in terms of declines in annual mohair yield per animal and deaths of animals. Knowledge of rainfall oscillations and the relationship between rainfall and mohair production in Lesotho would help farmers prepare themselves for drought years. The objectives of this study were: • 
To determine trends in Angora goat numbers, mohair production
and mohair yield per goat in Lesotho between 1935 and 1996 
• 
To determine the annual rainfall oscillations in Lesotho between
1935 and 1996 and estimate their possible impact on mohair production 
MATERIALS AND METHODS This study was carried out in Lesotho. Lesotho is a semitemperate country with cold winter and warm summer months. The temperature may range from 20 to 15.9^{o}C in winter and from 2436^{o}C in summer. The average annual rainfall is between 600 and 1775 mm, with most of the rain falling in summer (Bureau of Statistics, 1987; 2005). Owing to its mountainous character, much of Lesotho is well suited for Angora goat and sheep production (Hunter, 1987). Secondary data on annual rainfall, Angora goat numbers, mohair production and mohair yield per goat in Lesotho were used in this study. Major sources of this data were government reports, annual statistical bulletins, published research articles and books. The data collected covered the period between 1935 and 1996. However, trends in the above factors were calculated for the colonial period (19351965) and years of independence (19661996). These are distinct periods in terms of government policies, management practices and livestock production systems (Hunter, 1987). An exponential regression equation of the form LnY = LnA + bx (SAS, 2000) was used to estimate trends in annual Angora goat numbers, mohair production and mohair yield per goat. In this equation 'LnA' is the intercept, 'b' is the slope and 'x' is the time indexed to 1, 2, up to 31. Correlation analysis was used to estimate the relationships (r) between the above production parameters. Mean annual rainfall between 1935 and 1996 was calculated. Annual rainfall data was then calculated as deviations above or below the 62 year mean. This data was plotted on a graph paper to observe variations above and below the longterm mean. A tenyear weighted moving average was used as a simple smoothing and generalizing device (Dyer and Tyson, 1977; Eckert and Nobe, 1982). Patterns of wet (annual rainfall above longterm mean) and dry (annual rainfall below longterm mean) years were determined. RESULTS Between 1935 and 1965 Angora goat population in Lesotho increased (p<0.01) from 501,0001,018,000 at an annual rate of 1% (Table 1). Mohair production and mohair yield per goat increased at annual rates of 1.9 and 1.1%, respectively (p<0.01). There was some significant (p<0.01) indication that during that period growth in mohair production depended on annual growth in both Angora goat numbers and mohair yield per goat (Table 2). During years of independence (19661996) annual goat numbers remained, largely, stagnant (p>0.05) (Table 3). However, during this period mohair yield per goat declined at an annual rate of 1.2% to a value of around 0.85 kg (p<0.01). The end result was a decline in mohair production at an annual rate of 1.2% to 970,000 kg in 1996 (p<0.05). There were some significant (p<0.05) relationships between the decline in annual mohair production and the decline in both annual goat numbers and mohair yield per goat (Table 4).
Figure 1 presents graphical display of the annual rainfall
results. Annual rainfall is shown as deviation above or below the 62 year mean
of 700±113 mm (±SD). The data show that there were dry (rainfall
below longterm mean) and wet (rainfall above longterm mean) years. However,
no clear alternate oscillations of wet and dry years were observed. A positive
but nonsignificant (p>0.05) relationship between annual rainfall and annual
mohair yield per goat was observed (Table 5).
Table 1: 
Regression model for annual Angora goat numbers, mohair production
and mohair yield per goat in Lesotho between 1935 and 1965 

r = Correlation coefficient, P = Probability value, A = Intercept,
b = Slope or growth rate 
Table 2: 
Relationship between annual Angora goat numbers and mohair
production and between annual mohair yield per goat and mohair production
in Lesotho between 1935 and 1965 

r = Correlation coefficient, P = Probability value 
Table 3: 
Regression model for annual Angora goat numbers, mohair production
and mohair yield per goat in Lesotho between 1966 and 1996 

r = Correlation coefficient, P = Probability value, A = Intercept,
b = Slope or growth rate 
Table 4: 
Relationship between annual Angora goat numbers and mohair
production and between annual mohair yield per goat and mohair production
in Lesotho between 1966 and 1996 

r = Correlation coefficient, P = Probability value 
 Fig. 1: 
Annual rainfall deviations from longterm mean of 700 mm in
Lesotho between 1935 and 1996 
Table 5: 
Relationship between annual mohair yield per goat (kg) and
annual rainfall (mm) in Lesotho for the period 19351996 

r = Correlation coefficient, P = Probability value 
DISCUSSION
Annual mohair production can be influenced by the number of goats shorn and
mohair yield per goat (Drummond, 1985; Hunter, 1987). Between 1935 and 1965
annual goat numbers and mohair yield per goat increased. The overall result
was that there was an increase in annual mohair production. Thus, annual mohair
production depended on growth in both goat numbers and mohair yield per goat.
The growth in goat numbers may have been possible during that time because the
communal rangelands were still able to sustain more animals (Hunter, 1987).
However, the increase in goat numbers and other livestock species resulted in
overstocking and degradation of the communal rangelands (Phororo, 1979; Hunter,
1987). This, in turn, led to the communal rangelands being unable to sustain
good levels of livestock production (Hunter, 1987). Thus, between 1966 and 1996
annual goat numbers remained, largely, stagnant at around one million while
mohair yield per goat declined at an annual rate of 1.2%. Indeed, it could be
argued that the future prospects for increasing mohair production in Lesothomay
depend, mainly, on increasing the annual mohair yield per goat rather than on
increasing goat numbers. The low annual mohair yield of about 0.85 kg/goat may
be compared with a mean annual yield of about 4.0 kg mohair per goat (Bureau
of Statistics, 2000) in South Africa. Thus, improvements of around 370% are
possible.
Past Lesotho governments responded to the problems of low mohair yield per goat with a variety of policies and remedial programmes (Uys, 1977; Wyeth et al., 1983; Hunter, 1987). These included compulsory rotational grazing in the communal rangelands, exchange of old goats with young ones imported from South Africa, introduction of grazing fees, formation of associations, etc. However, it seems that past policies and remedial programmes did not have positive impact on annual growth of mohair yield per goat during the 19661996 period. It is, therefore, suggested that in future attention should be placed on increasing mohair production through improvements of mohair yield per goat. Initially, an attempt should be made to quantify the major factors that limit growth in mohair yield per goat. Then, policies and programmes putting more emphasis on those factors having higher limiting effects can be instituted. In the present study recorded data show that there were wet (rainfall above longterm mean) and dry (rainfall below longterm mean) years. However, there were no clear alternate oscillations of wet and dry periods as suggested by Eckert and Nobe (1982). In that study, which involved data from lowland districts of Lesotho only, there was some pattern of alternate 10 year periods of below or above longterm average annual rainfall. However, even in that study, there were a number of deviant years within wet or dry spells. It is, also, clear from the present study that drought (annual rainfall below longterm mean) was a recurrent feature in Lesotho during the period under study. This is similar to the findings of Eckert and Nobe (1982). There is, thus, a need for Angora goat farmers in Lesotho to have resources and knowledge so that they can prepare for drought and adjust their management strategies accordingly. Drought should be seen and treated as part of the whole livestock production industry and not as something which takes the country by surprise every now and then. The aim should be to minimize the impact of drought on livestock production. This will ensure the industry's sustain ability. Angora goats in Lesotho depend, mainly, on natural pastures for their nutritional requirements. These natural pastures depend on rainfall for their moisture requirements and hence their dry matter production (Phororo, 1979; De Waal, 1994). However, the relationship between annual rainfall and annual mohair yield per goat in Lesotho was very poor. Such poor relationship may indicate that there are other major factors determining annual mohair yield per goat (Hutchings and Stewart, 1953; Eckert and Nobe, 1982; De Waal, 1994). These include the rainfall distribution within the year and any intervention by the farmers in terms of feed supplementation to the animals (Eckert and Nobe, 1982; De Waal, 1994). Conclusion: The communal rangelands of Lesotho are not able to sustain the present Angora goat numbers, mohair yield per goat and mohair production. It is recommended that, in future, emphasis should be on increasing mohair production through improvement of mohair yield per goat. However, it is also important for Angora goat farmers to always have necessary resources and management skills for drought preparedness since drought was a recurrent feature in Lesotho. Although, the magnitude and extent of the impacts of such climatic changes on dry matter production of natural pastures and hence mohair production could not be well predicted from rainfall patterns during the period under study. Recommendations: It is therefore recommended that more research is needed to ascertain the relationship between annual rainfall oscillations and mohair production in Lesotho between 1996 and 2008 as this will help to add more knowledge on the magnitude and extent of the impacts of such climatic changes on dry matter production of natural pastures and hence mohair production in Lesotho for the benefit of the rural Angora goat farmers.

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