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Reproductive performance and level of gastro-intestinal parasite infestation in goats on-farm and on-station at Machang'a, Embu, Kenya

A.M. Okeyo, B.A.O. Inyangala, S.M. Githigia, S.J.M. Munyua,
M.M. Wanyoike, C.K. Gachuiri and M. Okomo

University of Nairobi, Faculty of Veterinary Medicine
P. O. Box 29053, Nairobi, Kenya

Abstract
Introduction
Materials and methods
Results and discussion
Helminthiasis
Conclusions
References

Abstract

Monitoring of an existing pre-experimental observatory herd of Small East African goats was carried out at Machang'a Field Station. For comparison, a rapid survey on 25 neighbouring farms was conducted. On-station, faecal samples were taken from the goats in January, February and June 1994 to establish eggs per gram (EPG) counts. The EPG's were low (0-800) in January and February but shot up to as high as 4200 in June. The most prevalent helminth species was Haemonchus contortus (78%). Reproductive parameters in goats on farms were examined. None of the farmers controlled breeding, abortions were common (75%) and udder problems featured in 42% of farms. Selection of breeding stock was based on visual appraisal. Kidding interval averaged 10 months, and twinning rates were low (12%) with a high survival rate (88%). Preweaning mortalities were very low. Other aspects of the study included feed and water availability, livestock composition and herd structure and reasons for disposal of stock. The most prevalent diseases included pneumonia, mange, helminthiasis, heartwater, ectoparasitism (fleas and ticks) and orf. The scope for genetic improvement of goats in Machang'a is great. Farmers require education on production and animal health aspects including ready access to veterinary services.

Introduction

Indigenous goat strains and breeds are usually credited for their relatively high tolerance of, or resistance to parasitic diseases and harsh environmental conditions, including long walking distances, poor quality herbage and long watering intervals. However, these desirable attributes are usually accompanied by poor growth, and carcass traits are usually negatively affected (Cartwright et al 1987; Ruvuna et al 1989).

The mechanisms of inheritance patterns of resistance to internal worms (particularly Haemonchus) are not yet fully understood (Bullerdieck 1989; Bain 1991). Also lacking are heritability estimates for resistance and its correlation with other growth, reproductive and dairy traits for indigenous goats in most parts of sub-Saharan Africa. Research results of studies conducted locally indicate that considerable variation exists in growth, prolificacy, fertility, carcass traits and dairy characteristics as well as tolerance. For example, Shavulimo (1989) in an artificial Haemonchus indoor challenge study, showed that the East African goat breed was more tolerant than the Galla. However, some individual Galla goats were even more tolerant of the parasite than their East African contemporaries. Ruvuna et al (1989) showed that some goat sires consistently imparted resistance to their offspring.

The usefulness of the above observations can only be realised when large-scale characterisation is carried out and genetic parameters generated, showing clear genetic relationships among all traits of economic importance (Baker 1991). It is then that meaningful selection criteria can be set and genetic selection programmes initiated to realise the set improvement objectives.

Long-term genetic studies that incorporate animal physiology, health and nutrition studies have not often been carried out due to the absence of an interdisciplinary approach to research, inconsistencies in research funding allocations or anticipation thereof, and lack of appropriate and accurate up to date technologies particularly laboratory supplies and expertise. These deficiencies have resulted in research findings that give incomplete pictures either through lack of precision or depth.

Inadequate nutrition coupled with high levels of parasite infestation contribute to high reproductive and productive wastage in small ruminant herds regardless of size and production system (Preston and Allonby 1979; ILCA 1988; ILCA 1989; ILCA 1990). Such wastage, also slows down genetic progress as select on intensities are substantially reduced.

Haemonchus is one of the major internal parasites of economic importance (Allonby 1974; Shavulimo 1989). Haemonchosis reduces productivity through reduced efficiency of nutrient utilisation and growth rate, in addition to mortalities which occur at severe infestation levels. Conventional means of controlling haemonchosis, such as grazing management and use of anthelmintics, are either not feasible or ineffective for various reasons. These reasons include the use of communally owned and grazed lands, anthelmintics that are not only too expensive for an ordinary farmer but are also environmentally hazardous, and the continuous development of resistance to these chemicals by the parasites at rates difficult for new products development to keep pace with.

New approaches and long-term alternatives to dealing with this problem include identifying tolerant or resistant individual animals within the local populations followed by efficient and extensive exploitation of such heritable merits in breeding programmes.

In order to identify such resistant/tolerant individuals, well designed genetic and breeding experiments that incorporate other related physiological and nutritional aspects need to be conducted. This project, through a multi-disciplinary approach, aims to yield the much needed prerequisite results for the characterisation of the East African and Galla goat breeds.

The objectives of this study are to:

· determine and compare variation in infestation rates of endoparasites between and within the East African and Galla goat breeds

· establish the underlying mechanisms involved in resistance/tolerance

· establish the incidence, predisposing factors and causes of pre-weaning mortality in goat flocks (the research flock and those of surrounding villages)

· develop economically feasible and versatile production packages for their recommendation to the regional stock keepers.

Materials and methods

The main study will revolve around a breeding experiment design that is summarised below:


Breed of goat


Males

Females*

Wet season

Dry season

Totals

East African

10

160 (10)

160 (10)

320 (20)

Galla

10

160 (10)

160 (10)

320.(20)

Total

20

320 (20)

320 (20)

640 (40)

* The figures in brackets indicate number of females left open as controls

The products of each season's mating will then be randomly subjected to various specific nutrition, artificial and natural helminthiasis challenges, and growth, carcass and reproductive performance measurements taken at both gross and tissue levels. Offspring of sires that show differences in tolerance levels will be randomly assigned to all such treatments in order to provide correlation estimates among the different traits. Individual animals that are at the extreme ends of the resistance scale and their progeny will further provide materials for molecular genetic studies. To fortify the research data base parallel studies on the surrounding farmers' flocks are being conducted. The detailed protocols are described by Okeyo et al (1991).

Location and environment of the area surveyed

The survey was carried out in Machang'a and Mavuria locations of Gachoka Division, Embu District in Kenya. Twenty-five farmers, each with at least a herd of 10 goats, were interviewed. The study area lies in climatic ecozone 4 (arid and semi-arid lands) at an altitude of 700 m above sea level. The average daily temperature is 28°C, with a mean annual rainfall of 650 mm, which follows a bimodal pattern. The long rains are from October to December and the short rains from March to May. The long rains are more reliable for cultivation of food crops.

Endoparasite infestation profile

A pre-experimental observatory herd was introduced at the research station in Machang'a and the prevalence of helminthiasis in these goats over the different seasons of the years was monitored. Comparative work on the farmers' herds was done through a rapid survey of the surrounding farms in the Mavuria Location. Seven goats died of heartwater from the Galla breeding herd newly introduced on the research station.

Faecal egg counts (EPG) were recorded over various seasons and genera of the helminths identified. Different tick species were also identified and their prevalence noted.

Others

Land tenure, feed and water availability, disease prevalence and control, animal husbandry practices and general livestock production systems were also addressed.

Results and discussion

The preliminary results of the studies carried out so far are summarised in Tables 1 to 4. Eighty per cent of the farmers lived on individually owned land, with the remaining 20% living on land owned by the local government (Embu Municipal Council). The acreage of the individually owned farms ranged from 4-37 acres, with an average of 11 acres per farmer.

Grazing system, feed and water availability

The grazing system practiced was mainly free range, while ensuring that the animals did not graze on cultivated. land. The grazing hours in the dry season ranged from 8-12 hours with an average of 10 hours. In the wet season this ranged from 8-10 hours with an average of 8 hours. This is so because in the wet season feed is readily available and the animals do not need to walk too far for it. Also during the wet season, most of the farmers have to work in the farms and hence have to cut down the hours they spend out grazing the animals.

About 37.5% of the farmers said they supplemented their animals' diet. This is done mainly in the dry season and the supplements given are acacia twigs and pods, and maize stover after harvesting the crop. Most of the animals were watered in the seasonal rivers, streams, ponds and dams. About 75% of these farmers experienced severe problems during the dry season as most watering points dried up and the animals had to be walked long distances to the existing water sources, such as River Thiba and dams (e.g. Kiambere dam). Stock numbers are drastically reduced during this period as a result of death by starvation, exhaustion and disease.

Livestock composition and herd structure

All farmers owned the East African goat breed, with a mean of 25 goats per farmer with a range of 10-90 (Table 1). The mean goat herd structure was 4 entire males, 13 females and 8 kids.

Most of the farmers identified their animals by ear-notching, one notch for the clan and one for the family. Colour and physical characteristics were also used in identification. Most of the farmers used visual appraisal and mental records to estimate ages and weights of their animals.

Table 1. The livestock species and average numbers kept by the local farmers.

Livestock species

Average numbers kept

Cattle

11

Sheep

7

Goats

25

Rabbits

4-6 Does

Poultry (chicken)

10-30

Bees

3-5 hives

Table 2. The structure, performance and health states of goat herds in Machang'a and Mavuria areas, Embu District, Kenya.


Category


Number

AFK1

Reproductive wastage (%)

Mortality rate

ABR2

KI3

(months)

Abortions

Parturient

Preweaning

(adults)*

(%)

(mo)

Adult females

13

12 (10-24)

3-30

12.5

na

8

12 (0-40)

10 (6-12)

Bucks (entire)

4

na

na

-

na


na

na

Kids/weaners

8

na

na

-

26


na

na

Total

25

12

3-30

12.5

26

8

12

12

Figures in brackets indicate the ranges of values observed
1 AFK = age at first kidding.
2 ABR = abortion rate.
3 KI = kidding interval in months.
* 46% of adult and kid mortalities were attributed to helminthiasis.
na = data not available.

Reproductive wastage and production performance levels

All the farmers reported that they did not control mating as the does graze together with the bucks. Besides, it is not uncommon to find several farmers' flocks grazing together. There are two breeding seasons per year for the goats according to 80% of the farmers interviewed. The age of the does at first kidding ranged from 10 to 24 months with an average of 12 months (Table 2).

Abortions occurred on 75% of the farms with a range of 3-30% of the herd affected. The causes, according to the farmers, were poor nutrition during drought, poisoning by feeding on immature acacia pods, helminthiasis, injury during fights and poisoning by certain minerals.

Forty-two per cent of the farmers reported that their does experienced udder problems which affected 4-25% of does in a herd. The problems were mainly teat injuries, orf lesions and occasional abscesses, but there was no clear-cut case of mastitis.

On selection of breeding males and females, most of the farmers based their decision on growth rate of the animals, general physical characteristics such as body condition and coat colour, in addition to udder size and twinning rates in the case of females. Other factors considered were lineage, strength of hind legs and length of ears. The average age of males at time of selection for breeding was 8 months.

The interval between kidding and the next service ranged from 2-8 months with an average of 4 months, while the kidding interval ranged from 6-12 months and averaged 10 months (Table 2).

The twinning rates ranged from 0-40% and averaged 12%, with an average of 88% of the twins surviving. This survival depended entirely on feed availability at the time of birth. Most farms experienced preweaning mortalities, with an average of 12.5% parturient deaths and 26% actual preweaning deaths (Table 2). The causes of the above deaths were, according to the farmers, diseases (46% of cases) mostly helminthiasis and flea infestation, poor nutrition especially during drought, poor mothering and predation by wild animals. A few farmers did not know the causes of the deaths.

Adult mortalities were also experienced in most of the farms, with an average of two deaths during the previous year. The major causes of these deaths were diseases such as hepatitis, helminthiasis, mange, pneumonia and in rare cases, trypanosomiasis.

All the farmers disposed of does by either sale or exchange (20%). Five goats are equivalent to one cow. The main reason for sale of animals was to generate income for school fees, buying food in times of famine and paying hospital bills. Other reasons for sale were for destocking and culling. Males were mainly culled (in 92% of the farms) for income generation and other reasons such as old age, replacement, infertility, sales for slaughter, destocking and selection against undesirable traits.

Disease prevalence and control

The most prevalent diseases affecting goats according to the farmers are listed below:

· Pneumonia (mavuli): Coughing, anorexia eye and nasal discharge
· Mange (uvele): Scratching, dandruff, alopecia
· Helminthiasis (danguru): Emaciation, rough hair coat, diarrhoea
· Heartwater (nduru): Recumbency, circling, uneasiness followed by death
· Ectoparasitism:

Fleas (nthua): Scratching, loss of condition
Ticks (ngova)

· Orf (meng'e): Pox lesions around nose and mouth
· Trypanosomiasis (kamocu): Wasting, then death
· Foot rot (mavungu): Lameness

Most of the farmers interviewed said they did not have easy access to veterinary services, and a few used herbal medicine to try and treat the various diseases. Hence most illnesses were fatal.

However, 83% of these farmers routinely drenched their animals 2-3 times a year while a few only did so when they saw signs of helminthiasis in their animals such as diarrhoea, rough hair coat and presence of worms in faeces. Most of the farmers used Wormicid Plus (R), a few used Nilzan (R), and 4% used herbs, for drenching their animals. When asked how, in their opinion, livestock production could be improved in the area, the farmers gave the following general answers:

1. Improved veterinary services to help in disease prevention and control and construction of dips etc.

2. Improved extension services to provide advice on good husbandry practices and information on crossbreeding to upgrade existing stock.

3. Improved nutrition of the animals, e.g. by supplementation during the dry season.

4. Provision of easily accessible watering points, by digging boreholes and dams.

Helminthiasis

East African goats (pre-experimental cleaning and observatory herd)

Faecal samples were taken from these goats in January and February 1994 and showed nil or low helminth egg count (range 0-800 EPG). These goats remained healthy during March through to April and started showing unthriftness in May (after end of rains) (Table 3). Faecal samples were taken on the first week of June and found to have high EPG. Over 60% had EPG counts of over 1000 and the range was 0-4200. Pooled faecal samples were cultured and larvae identified. Seventy-nine per cent of the larvae were Haemonchus contortus, 12% Trichostrongylus spp and 9% Ostertagia. Six goats had Moniezia expansa segments while most samples had coccidia oocysts (Table 4).

The goats were treated with Levamisole hydrochloride and they responded positively (i.e. recovered). They were healthy until the beginning of the short rains in mid-October when they again began to show unthriftiness. One goat showed submandibular oedema at this period of the year. Although they had low EPG's (Table 3), they were still treated as this could have been because most worms were immature and had not started laying eggs. Hypobiosis was also suspected since the pastures had not developed and the rainfall was not high enough to support development of infective larval stages in the pastures.

From the results in Table 3, it is evident that the EPG's remained low upto the beginning of the rains, after which there was an increase in the number of goats with high EPG counts. There was a sudden increase in EPG with the rains, a factor which could have been due to hypobiosis.

The worms identified showed that the species of major economic importance was Haemonchus contortus (Table 4). This worm is known to undergo hypobiosis in unfavourable weather. It is also the most pathogenic and was responsible for the sudden unthriftiness observed in these goats with the onset of the rains.

Galla goats

These were introduced at the end of August 1994. They were given time to adjust and faecal samples were taken on 14/10/94. The results are shown on Table 3. Pooled samples were cultured for larvae identification. The majority were Haemonchus followed by Trichostrongylus spp and Ostertagia spp (Table 4).

Table 3. The level of helminthiasis challenge in goats during the year at Machang'a (on-station).

Month

Number sampled

EPGs1

Proportion of herd (%)

Remarks

January



34

0-100

81.0

67.0% (NIL)

7

200-400

16.7


1

>400

3.3

2.42% (>800)

February



23

0-100

54.8

40.5% (NIL)

15

200-400

35.8


4

>400

9.5

5% (>800)

June




7

0-100

14.9

2.1% (NIL)

10

200-400

21.3


17

500-1000

25.5


18

>1000

38.3

21% (1800)

October2



61

0-100

80.2

56% (NIL)

16

200-400

18.2


1

>400

1.2

2.3% (>900)

1 EPG = eggs per gramme of faecal sample.
2 Only Galla goats sampled 1.5 months after introduction to the station.

Table 4. Prevalence (%) of gastro-intestinal parasites by, species.

Helminth (worm) species

Prevalence (%)1

Haemonchus contortus

79

Trichostrongylus sp

12

Ostertagia sp

9

Total

100

1 The percentages are based on actual larval counts following laboratory cultures.

Conclusions

From the above observations the following conclusions can be drawn:

· Goats form a major proportion of the stock owners' total livestock herds.

· There is no organised genetic selection programme in place at stock owners' level.

· Reproductive wastage due to various factors (abortions, parturient and preweaning mortalities, late age at first kidding, long kidding intervals) is high among the farmers' herds.

· Helminthiasis coupled with other opportunistic diseases such as pneumonia were the most common cause of mortalities among the herds.

· Haemonchus contortus was the major intestinal parasite responsible for the observed helminthiasis.

· Poor nutrition and ectoparasite (ticks and fleas) infestation in addition to others, were responsible for the observed low productivity in goat herds at farm level.

· The level of worm infestation and effect on the animals' health varied greatly depending on the prevailing weather conditions.

· Individual animals carried different levels of worms and coped with the burden differently regardless of season of the year.

Acknowledgement

The research work was funded by the African Small Ruminant Research Network (SRNET) of ILCA and the authors are grateful for the continued support.

References

Allonby E.W. 1974. Ovine haemonchosis: Epidemiology, clinical signs and diagnosis. In: Urquahrt G.M. and Armour J. (eds), Helminth Disease of Cattle, Sheep and Horses in Europe. Robert Maclehose and Company, London, UK.

Bain R. 1991. A review of research carried out at the National Veterinary Research Centre, Muguga, Kenya, on the genetic resistance of sheep to infection with gastrointestinal nematodes.

Baker R.L. 1991. Breeding for disease resistance - some historical perspectives, problems and prospects. Proceedings of New Zealand Society of Animal Production 51:1-13.

Bullerdieck P. 1989. Effect of anthelmintic treatment and supplement feeding on weight gain and packed cell volume of lambs in the coastal belt of Kenya. In: Proceedings of the Seventh SR-CRSP Scientific Workshop, Nairobi, Kenya, 22-23 February, 1989. SR-CRSP (Small Ruminant Collaborative Research Support Program)/APSK (Animal Production Society of Kenya), Nairobi, Kenya. pp. 141-147.

Cartwright T.C., Lentz E.L., Blackburn H.D., Tallam S.K. and Ruvuna R.F. 1987. The potential productivity of intensive smallholder goat dairies in Western Kenya. Proceedings of the Sixth SR-CRSP Scientific Workshop, Nairobi, Kenya. SR-CRSP (Small Ruminant Collaborative Research Support Program)/APSK (Animal Production Society of Kenya), Nairobi, Kenya.

ILCA (International Livestock Centre for Africa). 1988. ILCA Annual Report 1987. ILCA, Addis Ababa, Ethiopia. 105 pp.

ILCA (International Livestock Centre for Africa). 1989. ILCA Annual Report 1988. ILCA, Addis Ababa, Ethiopia. 156 pp.

ILCA (International Livestock Centre for Africa). 1990. ILCA Annual Report 1989. ILCA, Addis Ababa, Ethiopia. 144 pp.

Okeyo A.M., Inyangala B.A.O., Wanyoike M.M., Githigia S.M., Munyua S.J.M., Gachuiri C.K. and Okomo M. 1991. Genetic Studies of Galla and Small East African Goats and Their Correlated Growth and Reproduction Performance under Different Nutritional and Endoparasite Challenges. SRNET/EAST/MULTI/1 Project Proposal, 1992.

Preston J.M. and Allonby E.W. 1979. The influence of breed on susceptibility of sheep to H. contortus infection in Kenya. Research in Veterinary Science 26:134-139.

Ruvuna F., Ahuya C., Okeyo M. Cartwright T.C. 1989. Growth parameters of indigenous goat breeds and crosses with Toggenburg and Anglo Nubian. In: Proceedings of the Seventh SR-CRSP Scientific Workshop, Nairobi, Kenya, 22-23 February 1989. SR-CRSP (Small Ruminant Collaborative Research Support Program)/APSK (Animal Production Society of Kenya), Nairobi, Kenya. pp. 11-17.

Shavulimo R.S. 1989. Endoparasites as a constraint to goat improvement in Kenya. In: Wilson R.T. and Azeb Melaku (eds), African Small Ruminant Research and Development. Proceedings of a Conference held at Bamenda, Cameroon, 18-25 January 1989. ILCA (International Livestock Centre for Africa), Addis Ababa, Ethiopia. pp. 382-392.


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