Reproductive characteristics of Ethiopian highland sheep. I. Genetic parameters of testicular measurements in ram lambs and relationship with age at puberty in ewe lambs.

A study was conducted to estimate heritabilities of, and genetic correlations among, body weight (WT) and testicular measurements - scrotal circumference (SC), testicular diameter (TD), testicular length (TL) and epididymal diameter (ED) - in ram lambs between 6, 9 and 12 months old, and relationship of the testicular traits with age at puberty in ewe lambs (AP). Two fat-tailed sheep breeds, the Horro and Menz, indigenous to the Ethiopian highlands were studied. Experimental lambs were produced by mating 250 oestrus-synchronized ewes of each breed to 10 sires in a single-sire mating system over three mating periods which produced, for this study, a total of 361 ram lambs and 148 ewe lambs, with substantial pedigree information, in two dry seasons (October/November 1992 and 1993) and one wet season (June/July 1993).

Breed and season effects on the peri-parturient rise in nematode egg output in indigenous ewes in a cool tropical environment.

A study was carried out at the International Livestock Research Institute (ILRI) Debre Berhan Research Station in Ethiopia from 1992 to 1995 to compare the peri-parturient rise (PPR) in faecal nematode egg counts (FEC) in ewes of two indigenous sheep breeds. A total of 1439 Menz and 1347 Horro ewes were single sire mated following oestrus synchronization to lamb in the wet and dry season. Three ewe treatment groups were constituted as mated/lactating/undrenched; mated/lactating/drenched; unmated/undrenched for three wet and three dry lambing seasons.

The epidemiology of nematode infections in sheep in a cool tropical environment.

The epidemiology of nematode infections in Menz sheep was studied in the highlands of Ethiopia at the International Livestock Research Institute (ILRI), Debre Berhan Research Station, using a series of tracer lambs grazing contaminated pasture for either 4, 16, 32 or 48 weeks from July 1992 to June 1994. The basic nematode seasonal infectivity pattern was expressed in terms of relative numbers of third-stage larvae (L3) available on pasture for different months. Data from faecal nematode egg counts, pasture larval recoveries and worm counts from the tracer lambs were used to investigate the infectivity pattern.

Semen characteristics of Ile-de-France rams of different age and physical condition.

A breeding soundness examination (BSE) involving animal physical examination, scrotal circumference (SC) and semen evaluation was undertaken on 80 Ile-de-France rams at a government breeding farm, 32 km south-west of Casablanca (Morocco) from March to May 1988. A large percentage of rams (21.4%) was found to be unfit for breeding due to physical and genital abnormalities; 11 and 5% had disorders of the feet and respiratory system; upon genital palpation, 17.

[Livestock diseases in periurban dairy systems of sub-Saharan Africa: ILCA's approach].

Dairy production to supply African urban centers is one of the dynamic livestock sectors in sub-Saharan Africa (periurban dairy farms). There is a modification in the relative impact of economically important diseases: these farms have an increased capacity to control the major traditional African diseases through genetic or health interventions, hence favouring the emergence of diseases of intensification, which affect dairy production. In this framework, the International Livestock Centre for Africa is starting a research programme which aims, by an ecopathological approach, to judge the true existence of this pathology as opposed to the major African diseases, and to compare its economic importance in various agroecological zones.