GROWTH OF F1 BOS-TAURUS X BOS-INDICUS VERSUS BOS-INDICUS BEEF-CATTLE IN VENEZUELA .2. INITIAL, FINAL, AND CARCASS WEIGHT OF BULLS, AND BREEDING WEIGHT OF HEIFERS

Animals produced from zebu cows using semen of Brahman (B, control), C harolais (C), Limousin (L), Marchigiana (M), Romosinuano (Criollo, R) and Simmental (S) in experiment (E(1)), and semen of B (control) Angus (A), Chianina (K), Gelbvieh (G), L and S in experiment 2 (E(2)) were evaluated an two ranches in the Venezuelan floodplains. In E(1), initi al weight (IW), average daily gain (ADG) during the finishing period, final weight (FW) and carcass weight (CW) were recorded in bulls, whil e FW in bulls and weight before the breeding season (SW) in heifers we re recorded in E(2). After reaching 18 months of age, bulls were maint ained on savanna and cultivated pasture, and, during the finishing per iod, on cultivated pasture. Heifers were maintained on savanna until b reeding age. The following numbers of records were analysed by least-s quares procedures: 1. In E(1): 1262 IW; 1261 ADG; 1269 FW; 1265. CW; 2 . In E(2): 721 FW; 565 SW. In the model breed group, year and month of birth, sire within breed, year x month and age (linear and quadratic except in ADG) were mere included. Breed group was highly significant and all crossbred groups were superior to Brahman at all weights. Adju sted means for IW, ADG, FW and CW in E(1) were 304.1 +/- 2.3 kg (age 7 00 days), 742 +/- 9 g (period of 229 days), 467.8 +/- 3.2 kg (age 929 days) and 242.6 +/- 1.7 kg (age 929 days), respectively. In E(2), adju sted means for FW and SW a ere 478.2 +/- 1.9 kg (age 892 days) and 341 .6 +/- 2.4 kg (age 767 days), respectively. Mean superiority (and vari ation of means of extreme groups) of F-1 over B was: 1. In E(1): IW, 7 .9 (4.5-10.2)%; ADG, 12.2 (6.3-14.5)%; FW, 9.1 (5.1-13.3)%; CW, 10.3 ( 7.3-13.5)%; 2. In E(2): FW 7.2 (4.5-9.8)%; SW 12.2 (10.6-14.4)%. In E( 1), F-1 M and F-1 C were the best groups at all weights, and, for FW, these were F-1 K and F-1 S in E(2). The progeny of the best sire withi n breed for FW in E(1) and E(2) was 18.1 and 12.9% superior to that of the poorest. The average advantage of crossbreds over B in E(1) and E (2) was equivalent to 40 and 32: kg or 40 and 32 US$, while these valu es for the best groups were 58 and 44 kg, or 58 and 44 US$.