Lamb weights and daily gains from divergent genetic types of established purebreds, e.g., Dorset (D), Lincoln (L), Rambouillet (Ra), Suffolk (Su) and Targhee (T), and fecund-type breeds, e.g., Finnsheep (F) and Romanov (Ro), their reciprocal crosses and Suffolk sired specific cross Su(F × Ro) were evaluated. Also evaluated were lambs of the Outaouais (O) and Rideau (R) Arcott breeds and their reciprocal crosses, in addition to Synthetic I (½ F, ½ L), Synthetic II (½ D, ½ Ra) and Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) populations. The established purebreds produced heavier lambs at birth and weaning, Arcott breed crosses gained weight more rapidly resulting in heavier lambs at 140 d, and fecund-type breeds produced lighter lambs (P < 0.05). In general, daily gains and lamb weights of all genetic types were similar, except that fecund-type breeds produced significantly lighter lambs. Lamb weights of T were most at birth, and Su at weaning and 140 d, while F lambs weighed the least (P < 0.05). Within established purebreds, Su weighed the most and D weighed the least, while L, Ra and T lambs were intermediate. Daily gains including weaning and 140-d weights of F and R cross lambs benefited from 7–9% heterosis, while the Arcott breed cross lambs not only benefited from 5–8% heterosis, but were comparable with Su lambs. At the same time, lamb performance of Su(F × Ro) was similar to the average of their parental breeds. Lambs of synthetic populations relative to the average of their respective parental breeds weighed 8–24% more at 140 d, suggesting heterosis retention. Key words: Growth, North American breeds, Finnsheep, Romanov, Arcotts, synthetic populations
DISCOVERY OF NEW KIMBERLITE FIELDS ON THE SOUTHERN SLOPE OF THE LEONE-LIBERIAN SHIELD (Sierra Leone)
