Er Mutiga

Pathogenesis of Trypanosoma (brucei) evansi in small East African goats

Trypanosoma evansi is the cause of surra, a camel disease which is the most important single cause of economic losses in camel rearing areas. Sheep and goats herded with camels are the most likely hosts for T evansi. Upon intravenous infections goats developed erratic parasitaemia, lost weight and their packed cell volume dropped significantly (P < 0.001). Trypanosomes were demonstrated by direct microscopy in extravascular locations such as synovial, peritoneal and cerebrospinal fluids and also in lymph by subinoculations into mice. The carcases were emaciated and pale. Histologically there was lymphatic tissue hyperplasia, muscular atrophy and nephrotic changes. Two animals had necrotic foci in the liver, kidneys, lymph nodes, spleen and lungs and also bronchopneumonia. Histologically there was depopulation of lymphocytes in lymphatic tissues, destruction of hepatocytes in the liver with infiltration by inflammatory cells in the liver, lymph nodes, spleen and the kidneys.

Preliminary findings from an experimental study of caprine besnoitiosis in Kenya

Inoculation of cystozoites obtained from natural, chronic cases of caprine besnoitiosis produced clinical disease in goats but not in rabbits, mice, guinea pigs, hamsters, rats or cattle. Histological examination of tissue sections from the experimental animals showedBesnoitia cysts only in goats. This, together with field observations that cattle reared together with goats having besnoitiosis do not contract the disease, suggests that theBesnoitia species that infects goats in Kenya is host-specific and is notBesnoitia besnoiti. We suggest that the nameBesnoitia caprae be adopted for the caprine pathogen.

The effects of experimental Trypanosoma (Trypanozoon) (brucei) evansi infection on the fertility of male goats.

The effects on the fertility of small East African male goats of intravenous infection with Trypanosoma (t) (b) evansi were studied. Six infected bucks developed erratic, low but persistent parasitaemia, the packed cell volume dropped gradually but significantly (p<0.001) and they became emanciated. Half of these bucks developed clinical orchitis. Two bucks died of the disease during the experiment.Semen from all the infected bucks deteriorated in quality and quantity and those with clinical orchitis became totally aspermic. Spermatozoal abnormalities and the number of dead spermatozoa rose significantly. Later in the disease, the testicles of the infected bucks atrophied. Histologically, the testicles from the infected animals became devoid of spermatozoa, the testicular blood vessels contained microthrombi and there was infiltration of inflammatory cells. Subsequently, diffuse calcification set in, with calcium deposits obliterating most of the seminiferous vesicles and ducts and also the epididymal ducts.

Ovarian response, ova recovery and fertility in merino ewes superovulated either during the luteal phase of their oestrous cycle or after intravaginal progestagen treatment.

Five groups of merino ewes were treated with 1000 i.u. of pregnant mare serum gonadotropin (PMSG) as a single injection per ewe. Three of these groups received treatment on days 7,9 and 11 of their oestrous cycle. Oestrus was synchronized with 125 mg of prostaglandin F2(alpha) (PG) given two days after PMSG. Oestrus in the other two groups was synchronized by intravaginal progesterone sponges inserted for 14 days. In one group, the sponges were inserted nine days after oestrus onset. In the other group the stage of the oestrous cycle was unknown. In both these groups, PMSG was given a day prior to sponge removal. No significant differences were recorded for either the mean numbers of corpora lutea, unovulated follicles or ova recovery between the five groups. However, progestagen synchronized ewes yielded significantly more fertilized ova (p < 0.05) than PG synchronized ewes.

Comparative ultrastructural studies onBesnoitia besnoiti andBesnoitia caprae

Comparative transmission electron microscopy onBesnoitia besnoiti and on a strain ofBesnoitia derived from goats in Kenya revealed that the two organisms differ in their pellicle, micropore, microtubules, nucleus, wall-forming body 1 (W1), amount of lipids and amylopectin. Thus the caprine besnoitia is probably a different organism and the termBesnoitia caprae should continue to be used.

Increasing reproductive rates in tropical sheep by means of embryo transfer

One to three embryos were transferred to three groups each of 12 Kenya Merino ewes to establish if uterine capacity is a limiting factor to reproductive performance in this breed of sheep, in a tropical environment. A fourth group of 12 ewes received three embryos following superovulation. Multiple transfers increased the number of lambs born per pregnant ewe. However, although superovulation significantly (P<0.01) increased endogenous progesterone levels in Group 4 recipient ewes, it did not improve either their conception or lambing rates. Peri- and post-natal losses increased with the number of embryos trnasferred and with the litter size. Consequently, the same number of lambs were weaned per recipient ewe in all four groups. It is concluded that although the uterine capacity of the Kenyan Merino ewes is higher than their natural ovulation rates require, increasing the litter size will not necessarily increase the number of lambs weaned.

EMBRYO TRANSFER FROM EXOTIC TO INDIGENOUS GOATS IN KENYA

As the population of the developing world increases, the land avaihtble for food production is bound to decrease. Thii is p~tic~~ly so where land is divided between family members. If the demands for high quality proteins, particularly those of animal origin in the form of meat and milk are to be met, then the dairy goat may be the optimum animal for small units. The local East African goat is of little value as a milk producer. Although crossbreeding this breed with highly productive exotic animals should result in &spring of high productivity, this is a long term programme. More rapid gains could be achieved by using the technique of embryo transfer. In this way? many good qua&y animals could be obtained using an init% small nucteus of pure-bred highly productive dairy goats The work reported here was carried out in an attempt to increase rapidly the numbers of offspring from a small flock of Toggenburg dairy goats in order to meet a high demand.

Limitations of intrauterine balloon catheters for ova collection in sheep

Attempts were made to collect ova from superovulated ewes by surgically fitting a balloon catheter in each uterine lumen either during the luteal phase or follicular phase of their oestrous cycle. A total of six ovulations and 37 unovulated follicles were observed and one unfertilized, degenerating ovum was collected from the six catheterised ewes. This was significantly different (P < 0.01) from the 22 ovulations and eight unovulated follicles observed and the 14 ova recovered from the three control ewes. The presence of catheters prevented plasma LH peak during the oestrus following catheterisation, and as a result, ovulation failed as evidenced by the low plasma progesterone levels from that oestrus throughout the experiment. No pathogenic micro-organisms were isolated from the uteri of any of the ewes. However, histological studies showed infiltration of lymphocytes and monocytes in the endometrium of the catheterised ewes but not in the controls, indicating an immunological type of reaction to the presence of the catheters.