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Summary Ruminants adapt to periodic fluctuation in feed resources by accumulating fat stores during favourable periods. Thus, genetic variations, among ruminant genotypes, in the capacity to deposit fat could be exploited through breeding to improve animal productivity in traditional tropical production systems. Based on this premise, breed differences among weights of principal adipose depots and total body fat were estimated in Menz (n = 303) and Horro (n = 151) sheep of Ethiopia. Animals were kept on supplemental feeding, for about 3.5 months, until slaughter at about 17 months of age and pre‐slaughter live weight of 25 kg. Except the combined weight of tail and rump fat (TRF) which was similar (p > 0.05) in the two breeds, weights of subcutaneous and intermuscular fat (SIF), internal fat (IF) as well as total dissected body fat (TotDF), total ether‐extracted body fat (TotEE) and TotFAT (TotDF plus ‘residual’ fat, fat recovered by ether‐extraction from non‐adipose tissues) were significantly (p < 0.01) higher in the Menz. TotDF, TotEE and TotFAT were 1.91 ± 0.04, 2.05 ± 0.06 and 2.64 ± 0.06 kg, respectively, in the Menz and 1.50 ± 0.05, 1.44 ± 0.06 and 2.02 ± 0.07 kg, respectively, in the Horro. Implications of breed differences in fat distribution among depots, and possible consequences of genetic improvement of some of the depots on adaptation to climatic and nutritional stresses as well as some production objectives are discussed.

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Two types of locally produced live vaccines (HB1 and La Sota--lentogenic strains) and inactivated oil adjuvant (IOAV) vaccine were used to compare the efficiency of three vaccination techniques, namely drinking water, ocular and spray on broiler chicks. The ocular route of vaccination on 1-day-old chicks followed by a booster dose on the third week through the same route induced a significantly higher level of haemagglutination inhibition antibody titre (P < 0.0001). The highest mean antibody titre was log(2) 6.6 and 93.3% of the chicks were protected from the challenge. The spray technique induced a lower antibody titre (peak of log(2) 5.9) and only 53% of the chicks in this treatment survived against the challenge. The results of this study show that the ocular route is superior to the drinking water route, which is superior to the spray technique. The economic analysis result showed that the ocular HB1 and La Sota vaccine administration method to 1- and 21-day-old chicks gave the highest revenue followed by the drinking water method. In terms of total cost, the injection method required the highest cost (0.21 birr/chick) followed by the ocular method (0.18 birr/chick). The marginal cost of vaccine administration is too small compared with marginal revenues from relative effectiveness of the methods. The internal rate of return for the ocular method was very high. The results of sensitive analysis on revenues from different vaccination methods indicate that a 25% reduction in broiler price reduces the marginal revenue from the ocular method by 12 487 birr but this still does not prove that the ocular method is economically viable for small- and medium-scale poultry farms.