Search

Egg Production traits of Khaki Campbell, Alabio, Bali and Tegal ducks were measured to 68 weeks of age under intensive management. Khaki Campbell ducks laid significantly more eggs and required less feed per egg or per gram of egg produced than the Indonesian breeds. Appreciable numbers of local ducks were observed to moult on two occasions during the trial. It was thought that this may have been a response to seasonal factors such as rainfall patterns. Tegal ducks laid significantly fewer eggs and were less efficient than Alabio and Bali ducks. Egg specific gravity was consistently highest in the Alabio and Tegal breeds. The poor production of Tegal ducks compared with that in other studies may have been related to their early onset of lay under the 16 h daylength used in the trial or to a sampling effect.

Selection for post-weaning weight gain in mice from 21 to 42 days, on either a full or restricted feeding level during this period was carried out for seven generations. Control lines were maintained for each feeding level. The rate of selection response was higher on full feeding due to a higher heritability and a larger phenotypic variance. Realised heritabilities of 0.29±0.05 and 0.19±0.04 for selection on full and restricted feeding respectively, were in close agreement with base population estimates.Selection on full feeding led to positive correlated responses in 21 day weight, 42 day weight, food intake and efficiency between 21 and 42 days, and 42 day tail length, but with little change in reproductive performance.Correlated responses to selection on restricted feeding were reduced 21 day weight, but an increase in 42 day weight and increased efficiency from 21 to 42 days. However, overall reproductive performance fell.

Lamb production in relation to total feed consumption was recorded in Javanese thin tail (JTT) ewes and in first cross Suffolk x JTT (SX), Wiltshire Horn x JTT (WX) and Poll Dorset x JTT (DX) ewes over three successive lambings or for 21/2 years after joining with rams of the same genotypes in a continuous mating system. For the JTT, SX, WX and DX genotypes respectively, total numbers of lambs weaned per ewe joined were 3.77, 2.50, 2.08 and 1.33, mean lamb body weights at weaning were 12.8, 18.8, 18.6 and 20.9 kg, total weights of lamb weaned per ewe joined were 48.4, 46.9, 38.8 and 27.9 kg, and average weights of feed consumed by the whole production system per kg of lamb weaned were 16.4, 21.9, 23.5 and 32.8 kg. Thus cross-bred ewes required more feed to produce fewer though heavier lambs without any real increase in total productivity.