In very hot dry summer months of Souths Spain four lots of piale lambs were creep fed (3-4 lambs per lot, with 19 k av. live weight) and four lots of female lambs (3-8 animals per lot, with 15 k av. live weight) for 40 days with four typés of comparable concentrate pelleted rations; 1. Control, no additional fat, no extra bilis; 2. Added fat, plus 0,1 p. 100 bilis. 3. idded fat, without bilis. 4. No additional fat, plus 0,1 p. 100 extra bilis. Rations 1 and 4 had 2,21 p. 100 total fat; ra¬tions 2 and 3 had 7,69 p. 100 total fat.
Average lambs total growth were 5,59, 6,18, 6,00 and 4,00 for lots 1 to 4, respectively, no significant differences were detected among tratnients, but sexes performed significantly different. Feed conversion was 6,59, 5,71, 6,87 and 6,37 K/k for the lots 1 to 4, respectively.
Mesenteric plus renal fat were 3,50, 3,94, 3,25 and 3,67 p. 100 of carcass weight of male lambs in the four lots, no significantly different.
Pooling data of male lambs, a correlation coefficient of —0,35 was calculated between the live weight and the rectal thermic increment of lambs, being both numerical series relate by the regression equation Y = 9.21 —4.02X. The regre¬ssion equation of decenal. feed consumption by lots on average rectal thermic increment was Y = 2"8.2-E 13.54 X, being the correlation coefficient between both series 0.63.
The digestibility of the fat was in lots 1 to 4, respectively, 14.0, 56.7, 58.3, and 11.4 p. 100.
Feeding costs by live weight increment in pesetas per k was: lot 1, 60,20; lot 2, 52,30; lot 3, 67.90 and lot 4, 61.10. Relative cost indexes are: Control, 115.10; Fat + bilis, 100.00, Fat, 129.80; No fat, addes bilis, 116.80.
Despite the apparent non significant differences of treatments the promising economic results suggest to repeat the experiment with more lambs by lots and to extreme differences among treatments, a new experiment is now in progress.