Wira Pribadi, Sucik Maylinda, Moc. Nasich, S. Suyadi
The growth rate and efficiency of Bali Cattle and Bali x Simmental Crossbred cattle in lowland ( 0-100 m above sea level ) and upland ( 700-1100 m above sea level ) area of West Nusa Tenggara were evaluated by measuring the daily gain and feed intake of Bali breed (B ) x Simmental crossbred (SB), SB x Simmental back crossed (SB-S), and SB Bali back crossed (SB-B). All animal measured were male in sex of 2 years (730 days) old. The number of respective breeds was 45, 48, 40, and 34 bulls for lowland, 36, 45, 45, and 32 bulls for upland area. The animal were selected purposively from Artificial Insemination program of cows in the villages around both altitude areas. The daily environmental condition such as air temperature, relative humidity, and THI ( Temperature Humidity Index ), recorded were 30,27 0C, 63,36%, and 74,06 respectively for lowland, and 25,52 0C, 87,55%, and 69,40 for upland areas. The animals in those two areas were fed with forages with similar in amounts and quality. The growth efficiency was evaluated for the ratio of total digestible nutrient (TDN )/ gain. The results showed that the different crossing program and in the different altitude areas. While in lowland area, the SB-B male showed lowest growth efficiency (11.79 kg TDN/kg gain) compared to B male (8.41 kg TDN/kg gain), SB (11.431 kg TDN/kg gain) and (SB-B =9.27 kg TDN/kg gain), in the upland area, SB-S male showed highest growth efficiency ( 9,607 kg TDN/kg gain), compared to B male (10.22 kg TDN/kg gain), SB (10.09 kg TDN/kg gain), and SB-B ( 10.50kg TDN/kg.