Red Maasai Sheep Research Articles

Relative palatability and preference of sorghum silage, moringa or sesbania leaf meals by red Maasai sheep

Relative palatability and preference of sorghum silage, moringa or sesbania leaf meals by red Maasai sheep

Husbandry and Productivity of Red Maasai Sheep in Arumeru and Monduli Districts in Tanzania

This study was undertaken to describe the husbandry practices and productivity of the Red Maasai sheep in Arumeru and Moduli districts in Tanzania. Sixty three farmers from each of the two districts were interviewed. Data were analysed using SPSS computer package. All farmers (100%) practice an extensive production system where sheep graze together with cattle and goats. The majority (61.9%) of the farmers use communal land to graze their animals, and children are the main source (69.0%) of labour. Almost half (50.8%) of the farmers indicated to supplement their sheep with mainly (65.6%) maize bran. Identified constraints to production were diseases, drought, lack of capital, poor markets and extension services, thefts, and predators. A plastic apron was found to be an effective indigenous technique to control mating and practice seasonal breeding. Age at first lambing for the majority of Red Maasai sheep was 13 to 18 months and lambing intervals of 12 to 18 months. Most sheep lambed between October and January. Twinning cases were few (15.9%) indicating a low twinning rate in the population. Breeding rams were selected within flocks, and many farmers (95.2%) preferred seasonal breeding to allow ewes to lamb in the wet season. Disposals were done to get income, remove infertile ewes, and slaughter for food and rituals. Generally, the productivity of Red Maasai sheep was low due to poor husbandry practices. It was concluded that improved management was likely to enhance sustainable production and conserve the breed.

Phenotypic Characteristics of Red Maasai Sheep in Arumeru and Monduli Districts in Tanzania

Phenotypic Characteristics of Red Maasai Sheep in Arumeru and Monduli Districts in Tanzania

An On-Station Analysis of Factors Affecting Growth Traits of Pure Red Maasai and Dorper Sheep Breeds under an Extensive Production System.

This comparative study aimed to evaluate genetic and environmental factors' effects on the growth traits of lambs in Dorper and Red Maasai (RedM) sheep breeds. The data analyzed contained the following measurements: birth weight (Bwt), weaning weight (Wwt), yearling weight (Ywt), birth type (single or twins), and details on each lamb's dam (dam ID and age) and sire. Except for the RedM, whose birth weight decreased with time, both breeds generally showed an increase in other growth weights across the study period, with yearly variations affecting both breeds. Additionally, analysis by a linear mixed model with restricted maximum likelihood (REML) showed that only breed as a factor significantly (p < 0.05) influenced birth weight; breed, sex, and birth type all significantly (p < 0.05) influenced weaning weight, whereas season, sex, and dam age significantly (p < 0.05) influenced yearling weight. The RedM breed outperformed the Dorper breed in post-weaning growth rate, demonstrating early resilience and adaptation to local environmental factors independent of maternal influence. Breed and non-genetic factors play a vital role in the growth of lambs, and the results of this study offer an opportunity for improved farm management under an extensive production system and selection for the conservation of the indigenous Red Maasai breed.

Impacts of climate-smart crop varieties and livestock breeds on the food security of smallholder farmers in Kenya

This paper analyses the impact of climate-smart agriculture (CSA) technologies on household dietary diversity and food insufficiency as indicators of food and nutrition security in Kenya. Using a combination of Propensity Score Matching and endogenous treatment effect approaches, we found that adoption of stress-tolerant varieties of several crops (such as bean, pigeon pea, cowpea, maize and sorghum) improved household dietary diversity score by 40% and reduced food insufficiency by 75%. Adoption of improved and resilient livestock breeds (including Red Maasai sheep and Galla goats) improved household dietary diversity by 38% while reducing household food insufficiency by 90%. We also found that stress-tolerant crop varieties were more effective in improving food security outcomes among households with large landholdings and with more educated and younger to middle-age heads. Effects of resilient livestock breeds on household food security were much stronger for households with large landholdings and with young and/or much older heads that have low levels of education. Given the large, demonstrated benefits from the use of the CSA technologies, policies and programs aimed at their promotion should apply appropriate targeting to ensure wider uptake of the technologies and maximum returns on investment.

Genetic parameters and genetic trends for growth traits of the Red Maasai sheep and its crosses to Dorper sheep under extensive production system in Kenya

The Red Maasai are indigenous sheep breeds known for their adaptability in arid and semi-arid environments while the Dorper is known for its good mutton production. A field experiment cross breeding program for the two breeds was set up in 2003 to exploit these traits. In this paper, we present the genetic parameters for birth weight (BWT), weaning weight (WWT) and weight at nine months (MWT) for pure Red Maasai (RRRR), pure Dorper (DDDD), 75% Dorper (DDDR) and 50% Dorper (DDRR) breeds. The genetic parameters were estimated by fitting four different multivariate animal models while ignoring or including maternal effects. The model with the lowest Akaike’s Information Criterion (AIC) was chosen as the best model for the estimation of genetic parameters. The average annual genetic gain of the studied traits for each breed group was estimated by regressing the estimated breeding values on year of birth. Records from 5442 lambs recorded over a period of 17 years (2003-2019) were used in this analysis. The breed group, sex, type of birth, season of birth and age of the dam significantly (P < 0.001) affected the weights of the animals. The direct heritability estimates for BWT, WWT and MWT were highest in the RRRR (0.40 ± 0.08, 0.39 ± 0.08, 0.45 ± 0.08 respectively). Direct heritability was lowest for BWT in the DDDR (0.18 ± 0.06), and for WWT and MWT in the DDDD (0.10 ± 0.07, 0.08 ± 0.06 respectively). The maternal heritability estimates were highest in BWT for DDRR (0.12 ± 0.05) and at WWT for DDDD (0.05 ± 0.03), and lowest in BWT for DDDR (0.03 ± 0.03) and at WWT for DDRR (0.00 ± 0.01). The maternal heritability for MWT for all the breed groups was close to zero. Genetic and phenotypic correlations between the traits were all high and positive across all breed groups. The phenotypic correlations ranged from 0.41 to 0.73 while the genetic correlations ranged from 0.40 to 0.99. The pure Red Maasai had an average annual genetic gain of 0.012 ± 0.005 kg, 0.144 ± 0.037 kg and 0.170 ± 0.047 kg for BWT, WWT and MWT respectively while the pure Dorper had an average annual genetic gain of 0.006 ± 0.006 for BWT, 0.047 ± 0.033 for WWT and 0.069 ± 0.044 for MWT. Between the crosses, the 50% Dorper had higher annual genetic gains for all the traits. The observed genetic gains demonstrate that selective breeding based on estimated breeding values can lead to significant genetic improvement in the Red Maasai sheep and its crosses.

Purebreeding of Red Maasai and crossbreeding with Dorper sheep in different environments in Kenya.

The aim of this article was to study opportunities for improvement of the indigenous and threatened Red Maasai sheep (RM) in Kenya, by comparing purebreeding with crossbreeding with Dorper sheep (D) as a terminal breed, in two different environments (Env. A and a harsher Env. B), assuming different levels of genotype-by-environment interaction (G×E). Breeding goals differed between environments and breeds. Four scenarios of nucleus breeding schemes were stochastically simulated, with the nucleus in Env. A. Overall, results showed an increase in carcass weight produced per ewe by more than 10% over 15years. Genetic gain in carcass weight was 0.17 genetic SD/year (0.2kg/year) across scenarios for RM in the less harsh Env. A. For survival and milk yield, the gain was lower (0.04-0.05 genetic SD/year). With stronger G×E, the gain in the commercial tier for RM in the harsher Env. B became increasingly lower. Selection of females also within the commercial tier gave slightly higher genetic gain. The scenario with purebreeding of RM and a subnucleus in Env. B gave the highest total income and quantity of meat. However, quantity of meat in Env. A increased slightly from having crossbreeding with D, whereas that in Env. B decreased. A simple and well-designed nucleus breeding programme would increase the genetic potential of RM. Crossbreeding of RM with D is not recommended for harsh environmental conditions due to the large breed differences expected in that environment.

Live weight, conformation, carcass traits and economic values of ram lambs of Red Maasai and Dorper sheep and their crosses

Meat production is the most important trait in the breeding objectives of sheep production in East Africa. The aim of this study was to investigate breed differences in live weight, conformation, carcass traits and economic values for meat production among Red Maasai and Dorper sheep and their crosses. In total, 88 ram lambs, which were reared at the ILRI experimental station, Kapiti plains Estate in Central Kenya, were used for the study. The lambs were slaughtered at Kenya Meat Commission (KMC) at about 1 year of age. Prior to slaughter, the lambs were weighed, measured and assessed by experienced evaluators, and at the abattoir carcass traits were recorded. Large breed differences were found for most traits. Dorper lambs were heavier at delivery for slaughter and had better carcass grade but lower dressing percentage and fat levels than Red Maasai. Crossbreds were generally better than the parental breeds. Evaluators were willing to pay more for the Dorper lambs for slaughter although carcass weights later were shown not to be higher than for Red Maasai. Evaluators undervalued Red Maasai lambs by 8–13 % compared to Dorper lambs according to the prices quoted per kilogramme live or carcass weight by KMC. Live weight was better than any other live measure in predicting carcass weight. Due to the overall higher ranking of the crossbred lambs for meat production, Dorper may be useful as a terminal sire breed for crossing with Red Maasai ewes.

Participatory definition of breeding objectives for sheep breeds under pastoral systems--the case of Red Maasai and Dorper sheep in Kenya.

Crossing local breeds with exotic breeds may be an option for increased livestock productivity. However, there is a risk for endangerment of the local breeds. One such case is in Kenya where the imported Dorper breed is used for crossbreeding with Red Maasai sheep. The aim of this study was to investigate farmers’ trait preferences as a basis for determination of breeding objectives for Red Maasai and Dorper sheep at two sites, Amboseli and Isinya, in Kenya. Within their own flock, each farmer identified three ewes representing the best, average and poorest within each breed group: Red Maasai, Dorper and Crosses. Farmers gave reasons for their ranking. Body measurements and weights were also taken. At the harshest site, Amboseli, differences between breed groups in body weight were small and breeds were equally preferred. In Isinya, where environmental conditions are better and farmers are more market oriented, Dorper and Crosses had significantly higher body weights and market prices and were thus preferred by the farmers. Red Maasai were preferred for their maternal and adaptive traits. Breeding objectives should emphasize growth traits and milk production in both breeds at both sites. Body condition needs to be specifically considered in the breeding objectives for sheep in Amboseli, whereas adaptive traits need to be generally emphasized in Dorper.

Identification of novel loci associated with gastrointestinal parasite resistance in a Red Maasai x Dorper backcross population.

Gastrointestinal (GI) parasitic infection is the main health constraint for small ruminant production, causing loss of weight and/or death. Red Maasai sheep have adapted to a tropical environment where extreme parasite exposure is a constant, especially with highly pathogenic Haemonchus contortus. This breed has been reported to be resistant to gastrointestinal parasite infection, hence it is considered an invaluable resource to study associations between host genetics and resistance. The aim of this study was to identify polymorphisms strongly associated with host resistance in a double backcross population derived from Red Maasai and Dorper sheep using a SNP-based GWAS analysis. The animals that were genotyped represented the most resistant and susceptible individuals based on the tails of phenotypic distribution (10% each) for average faecal egg counts (AVFEC). AVFEC, packed cell volume (AVPCV), and live weight (AVLWT) were adjusted for fixed effects and co-variables, and an association analysis was run using EMMAX. Revised significance levels were calculated using 100,000 permutation tests. The top five significant SNP markers with - log10 p-values >3.794 were observed on five different chromosomes for AVFEC, and BLUPPf90/PostGSf90 results confirmed EMMAX significant regions for this trait. One of these regions included a cluster of significant SNP on chromosome (Chr) 6 not in linkage disequilibrium to each other. This genomic location contains annotated genes involved in cytokine signalling, haemostasis and mucus biosynthesis. Only one association detected on Chr 7 was significant for both AVPCV and AVLWT. The results generated here reveal candidate immune variants for genes involved in differential response to infection and provide additional SNP marker information that has potential to aid selection of resistance to gastrointestinal parasites in sheep of a similar genetic background to the double backcross population.

A case study on cryopreservation of African sheep semen for the Red Maasai, Dorper breeds and their crosses

The objective of this study was to examine the effect of different concentrations of trehalose and raffinose in Tris-citric acid-glucose (TCG) egg yolk extender for the sperm freezability of Red Maasai sheep, another African breed- the Dorper and their crosses. The results showed that Red Maasai, Dorper and their crosses sperm could be cryopreserved by extending with 0.075 to 0.01 M trehalose or raffinose-TCG egg yolk extender. We conclude that the cryopreservation of currently under threat Red Maasai sheep due to uncontrolled exotic breeds sperm makes it possible to establish a gene bank for the storage of animal genetic resources for endangered species, under the management of the International Livestock Research Institute for future genetic options in an uncertain world. Key words: Red Maasai sheep sperm, freezability, raffinose, trehalose.

Growth, carcass yield and meat quality attributes of Red Maasai sheep fed wheat straw-based diets

Thirty-two castrated Red Maasai sheep (12.7kg initial body weight, aged 12-18months), were used in an 84-day experiment to evaluate diets based on treated straw upon growth performance, carcass yield and meat quality. The animals were blocked by weight into four similar groups and randomly allotted into four dietary treatments, with eight individually fed animals per treatment. The dietary treatments were ad libitum untreated wheat straw (UTS), wheat straw treated with urea and lime (TS), straw and ad libitum hay (UTSH), and TS and ad libitum hay (TSH). In addition, each experimental animal received 220g/day (on as fed basis) of a concentrate diet. Treatment of straw increased (P < 0.05) dry matter intake (42.3 vs. 33.7g/kg W (75)/day), energy intake (4.6 vs. 3.7MJ ME/d) and the average daily gain (40.7 vs. 23.1g). Animals on TS produced heavier (P < 0.05) carcasses (6.6 vs. 5.4kg) with superior conformation than animals on UTS. Percentage cooking loss was higher in carcasses from animals fed TS compared to those from other diets. Except M. longissimus dorsi and M. semitendinosus, tenderness of muscles was not affected by diet but ageing of meat improved (P < 0.001) tenderness. Overall, straw treatment increased carcass yields with limited effects on meat quality attributes.

Prion protein (PrP) gene polymorphism in Red Maasai and Black Head Persian sheep breeds in Tanzania: Consistent profile regardless of locations

The status of scrapie in Africa is largely unknown. The susceptibility to scrapie and its pathology is determined by amino acid polymorphisms at positions 136 (A/V), 154 (R/H) and 171 (Q/R/H) of the ovine PrP gene (PrP genotype) of the animals. Despite the widely studied PrP gene polymorphisms worldwide, limited data is available on PrP genotypes of sheep from the African continent. Previously, we have reported six PrP genotypes derived from four different alleles in Red Maasai and Black Herd Persian (BHP), the ARQ/ARQ genotype being more frequent in the Red Maasai than in the BHP sheep. The highly susceptible VRQ allele was not found in any of the sheep breeds; the ARR allele was absent in the Red Maasai or occurred at a low frequency in the BHP. The lack of the highly susceptible VRQ alleles among Tanzanian sheep examined, necessitated further examinations on genetic susceptibility in sheep of the same breeds, but originating from an entirely different part of Tanzania. Consistently, ARQ/ARQ genotype was observed in 88% of Red Maasai and 64% of BHP sheep, ARQ/AHQ genotype was present in 12% in Red Maasai and 36% in BHP. Neither the highly resistant (ARR/ARR), nor the highly susceptible (VRQ/VRQ) genotypes were found. The ARQ and AHQ were the only alleles observed. The ARQ allele constituted 94%, 82% and 67% in the Red Maasai, BHP and cross-bred sheep, respectively. The AHQ constituted 6%, 18% and 33%, respectively. Data reported here, provide additional information on genetic susceptibility of the Red Maasai, BHP and their crosses; they may be helpful in policy formulation for future prevention of scrapie.

Small ruminant production in smallholder and pastoral/extensive farming systems in Kenya

A survey was conducted by way of personal interviews with 562 respondents comprising 459 farmers and 103 butchers/traders in selected districts in the central and western parts of Kenya, consisting of three predominantly smallholder and four predominantly pastoral/extensive districts. The study aimed to provide a better understanding of smallholder and pastoral/extensive sheep and goat farming systems in the tropics, by taking Kenya as an example. The results showed that 58% of the pastoral/extensive farmers and 46% of the smallholders indicated livestock as their main activity. Small ruminants ranked closely behind cattle in their importance. Thirty-four percent of the households kept only sheep, 18% only goats and 48% both species. The survey demonstrated the relative importance to the farmers of tangible benefits of farming sheep and goats (e.g., regular cash income, meat, manure and, in the case of goats, milk) versus intangible benefits (e.g., the role of small ruminants as an insurance against emergencies). Regular cash income and an insurance against emergencies were the highest priorities. Seventy-eight percent of the farmers reported animal sales over the previous 12 months of the survey date. Of these sales, the income was spent on school fees (32%), purchase of food (22%), farm investment (18%), medical expenses (10%), off-farm investment (9%), social activities (5%) and re-stocking (4%). Indigenous genotypes were predominant among the pastoralists and mixed crosses predominant among the smallholders. A range of traits: growth rate, body size, body shape, drought tolerance, meat quality, fertility, disease and heat tolerance, prolificacy and temperament were all considered important for both sheep and goats in both farming systems and across the different genotypes. Compared with other pure breeds, the Red Maasai sheep and the Small East African goats were rated poorly in terms of body size, body shape, growth and fertility, but highly in terms of drought and (for the Red Maasai) heat tolerance by both smallholder and pastoralist farmers. In general, crosses were perceived less favourably than indigenous pure breeds. Body size and performance ranked as the most important traits in the choice of breeding males. Approximately half the farmers inherited their males, reared them on the farm and kept them for an average of 2–3 years. Uncontrolled mating within the household's flock was predominant in both farming systems. Over 98% of the farmers reported incidence of disease, especially pneumonia (in pastoral/extensive areas), helminthosis, tick-borne diseases, diarrhoea and foot-rot. Over 95% of the farmers fed supplements in both dry and wet seasons. Pure exotic and indigenous × exotic genotypes fetched higher prices than indigenous genotypes due to their heavier body weight. In conclusion, the foregoing issues need attention in genetic improvement programmes, with more emphasis on the conservation and utilisation of indigenous small ruminant genotypes.

Seroprevalence of &lt;i&gt;Ehrlichia ruminantium&lt;/i&gt; (heartwater) in small ruminants in a pastoral production system in Narok district, Kenya

A survey was undertaken on the prevalence of heartwater in Narok district, Kenya as a component of a broader study to establish constraints to livestock production in a Maasai pastoral production system. Serum samples were collected on a single occasion from 147 Red Maasai sheep and 149 Small East African goats aged 6 months to 3 years from three sites in the district. The sera were tested for antibodies to Ehrlichia ruminantium, by a MAP1 B ELISA. The sero-prevalence of E. ruminantium ranged from 62% to 82.5% in sheep, while in goats the range was 42.5% to 52%. Brain crush smears prepared from a dead sheep on the study site were positive for E. ruminantium organisms thus confirming the presence of the disease. The most prevalent tick species observed on the animals was Rhipicephallus appendiculatus with a mean tick count per animal of 3.98 to 5.67 while the mean tick count for Amblyomma variegatum, the vector of heartwater, was 0.015 to 0.12 per animal. The results of the study do suggest that the farmers need to adopt a regular tick control programme to prevent the susceptible animals from getting infected with heartwater. Keywords: seroprevalence, survey, pastoral production system, sheep and goats, Ehrlichia ruminantium Bulletin of Animal Health and Production in Africa Vol. 54(1) 2006: 23-33

Comparative tick counts on game, cattle and sheep on a working game ranch in Kenya

The main objective of the study was to determine the possible influence of host species on the maintenance of ticks in the field by determining the relative contribution of game animals compared to domestic animals. The study was carried out on a game ranch 32 km south-east of Nairobi. Tick counts were carried out on 30 Zebu cattle (Bos indicus) aged 1 to 3 years and 20 red Maasai sheep (Ovis aries) aged 6 months to 1 year grazing with game animals in a common area for a period of 2 years and these counts were compared with those on eland and Thomson's gazelle. Half-body counts were carried out on the cattle and sheep once every week. To avoid excessive stress, the animals were dipped in amitraz whenever the half body counts exceeded 50 fully engorged female ticks of any species. Tick counts on two wild animal species (eland (Taurotragus oryx) and Thomson's gazelle (Gazella thomsonii)) were carried out during the weekly culling of the herbivores. The results revealed that there was no significant difference in the number ticks per square metre between the wild ungulates and the domestic animals.

Genotype by environment interactions for productivity and resistance to gastro-intestinal nematode parasites in Red Maasai and Dorper sheep

AbstractRed Maasai and Dorper sheep were evaluated for their resistance to gastro-intestinal (GI) nematode parasites (predominantly Haemonchus contortus), productivity and productive efficiency (assessed on a metabolizable energy basis) in experiments undertaken at the Kenyan coast (sub-humid environment) and the Kenya highlands (semi-arid environment). In both ewes and lambs there were few significant genotype by environment (G X E) interactions for either resistance (assessed by faecal egg counts-FEC) or resilience (assessed by blood packed red cell volume-PCV) to GI nematodes. Red Maasai sheep were consistently more resistant (low FEC) and more resilient (high PCV) than Dorper sheep. However, there were significant G X £ interactions for ewe reproductive performance and for ewe and lamb mortality rates and live weights. These interactions were due to very poor performance of the Dorper compared to the Red Maasai in the sub-humid coastal environment and to the much improved performance of the Dorper in the semi-arid environment. When these component traits were combined into estimates of flock productivity and productive efficiency there were highly significant GXE interactions with the Red Maasai sheep being considerably more efficient than Dorper sheep in the sub-humid environment, while in the semi-arid environment there was a negligible breed difference in productive efficiency. The results are discussed in terms of breeding strategies for smallholder farmers and pastoralists managing sheep in low-input systems in sub-humid and semi-arid environments.

Effect of protein supplementation and urea treatment on utilization of maize stover by Red Maasai sheep

Six Red Maasai sheep were used to investigate the effects of urea treatment and cotton seed cake supplementation of maize stover on intake, digestibility and rumen fermentation parameters. The basal feeds were Rhodes grass (Chloris gayana) hay (H), untreated maize (Zea mays) stover (US) and treated maize stover (TS), each of which was supplemented with 100 g of cotton seed cake (CSC) to make H+CSC, US+CSC and TS+CSC. These were offered over four feeding periods in a completely randomized block design, with periods serving as blocks. Hay and US treatments had similar intakes, digestibility, ruminal fluid volatile fatty acid (VFA) concentrations and pH. Urea treatment of the stover increased the digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and cellulose as well as the rumen ammonia nitrogen (AN) concentration. Cotton seed cake supplementation increased DM, OM and CP digestibility in US from 445 to 614 g/kg, 475 to 633 g/kg and 308 to 604 g/kg, respectively and VFA concentration in the rumen from 31 to 196 mmol/L. Supplementation of treated stover, increased the AN concentration (137 vs. 234 mg/l) rumen in the rumen content with no effect on nutrient digestibility and VFA concentration. The pH of the ruminal content for the diets ranged from 6.83 to 7.12. The trends of rumen AN and VFA for supplemented diets showed a gradual rise to a maximum three hours post-feeding, followed by a decrease in their respective concentrations. It was concluded that urea treatment and CSC supplementation of stover increased its utilization but supplementation of treated stover with CSC was not effective. Key Words: Sheep, Ruminal fermentation, Maize stover, Urea treatment SA Jnl Animal Sci Vol.34(1) 2004: 23-30

Genetic resistance to endoparasites in sheep and goats. A review of genetic resistance to gastrointestinal nematode parasites in sheep and goats in the tropics and evidence for resistance in some sheep and goat breeds in sub-humid coastal Kenya

SummaryThe evidence for both between- and within- breed genetic variation for resistance to gastrointestinal (GI) nematode parasites is reviewed. It is concluded that much of the published research on breed characterisation for resistance suffers from poor experimental design. Prior to the initiation of a 6-year study that has just been completed in coastal Kenya there were no estimates of within-breed genetic variation (i.e. heritabilities) of resistance in sheep or goats in the tropics. This study has confirmed that Red Maasai sheep and Small East African (SEA) goats are more resistant to GI parasites (predominantly Haemonchus contortus) than Dorper sheep and Galla goats. Heritability estimates for logarithm transformed faecal egg counts (an indicator of resistance) in 8-month-old lambs was 0.18±0.08 for all lambs, but higher in the susceptible Dorper-sired lambs (0.35±0.16) than in the resistant Red Maasai-sired lambs (0.06±0.07). This difference in heritability suggests that many centuries of natural selection have fixed most of the genes for resistance in the Red Maasai sheep. The resistant Red Maasai sheep and SEA goats were two to three times more productive than the susceptible Dorper sheep and Galla goats in the sub-humid coastal Kenya environment.

Resistance of four sheep breeds to natural and subsequent artificial Haemonchus contortus infection

The response of Red Maasai sheep to natural and artificial Haemonchus contortus infections was compared with sheep of Blackheaded Somali, Dorper and Romney Marsh breeds. Significant breed differences in egg count, packed cell volume (PCV), and mortality rates showed that the Red Maasai sheep were more resistant to natural H. contortus infection than sheep from the other three breeds. Of the initial groups of 15 wethers of each breed, two animals from each of the Dorper and Blackheaded Somali groups and nine from the Romney Marsh group died with heamonchosis during a 12 month field study. Following artificial infection of the Red Maasai, Dorpers and Blackheaded Somalis, with 10 000 H. contortus L3, the Red Maasai sheep maintained a lower egg output and a higher PCV than animals of the other two breeds. The results clearly showed that breed substitution with the Red Maasai is a control option in areas where sheep are kept for meat and H. contortus is endemic.