This research has been conducted in Naikoten 1, Kota Raja, Kupang city or 3 months. The purpose of this research was to investigate the performance of growth and heritability value from mating group between Local rooster and Isa Brown laying hen. The method used in this research is experimental method. The experimental design used was Complete Randomized Design (CRD) of three treatments in the form of three types of rooster and three replications. The treatment is Saras = Sabu >< Isa Brown, Bakoras = Bangkok >< Isa Brown, Leguras = Leher Gundul >< Isa Brown. The variables measured are hatching weight, body weight, body weight gain, feed consumption, feed conversion, carcass weight, abdominal fat percentage and heritability value of the parameter. The results indicated that the average of cross breed showed excellent growth performance and there is an indication of heterosis effect. The highest heritability value found at carcass weight parameter and hatch weight parameter. Based on the result, it could be concluded that the best growth performance is cross with Bangkok rooster. ABSTRAKPenelitian ini telah dilaksanakan di Kelurahan Naikoten I, Kecamatan Kota Raja, Kota Kupang selama 3 (tiga) bulan. Penelitian ini bertujuan untuk mengetahui performa pertumbuhan dan besarnya nilai heritabilitas dari kelompok ayam hasil persilangan, antara ayam pejantan lokal dan ayam betina ras petelur jenis Isa Brown. Metode percobaan eksperimental merupakan metode yang digunakan dalam penelitian ini. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) terdiri dari tiga perlakuan yang berupa tiga jenis ayam jantan dan tiga ulangan. Perlakuan yang dimaksud adalah Saras = Sabu >< Isa Brown, Bakoras = Bangkok >< Isa Brown, Leguras = Leher Gundul >< Isa Brown. Variabel yang diukur antara bobot tetas, bobot badan, pertambahan bobot badan, konsumsi ransum, konversi ransum, bobot karkas, persentase lemak abdominal dan nilai heritabilitas dari parameter tersebut. Hasil penelitian menunjukkan bahwa rata-rata ayam hasil persilangan menunjukkan performa pertumbuhan yang sangat baik dan ada indikasi terjadinya efek heterosis. Nilai heritabilitas tertinggi terdapat pada parameter bobot karkas dan bobot tetas. Berdasarkan hasil penelitian disimpulkan bahwa performa pertumbuhan terbaik terdapat pada kelompok persilangan dengan pejantan Bangkok.Kata kunci: Persilangan, performa pertumbuhan, heritabilitas.

A study has been conducted to determine the quality and effect of seaweed (Ulva lactuca) as a substitute feed for Bali weaned bull in the dry season with different energy levels. The research was conducted in two stages of in vitro treatment to determine the ideal level of U. lactuca flour with treatment of RA= hay natural grass; RAK= RA + concentrate; RAKU5= RAK + U. lactuca 5%; RAKU10= RAK + U. lactuca 10%; RAKU15= RAK + U. lactuca 15%; RAKU20= RAK + U. lactuca 20%. Stage two used Latin Square design with treatment of R1 = EM 7,3 MJ, R2 = EM 8 MJ dan R3 = EM 8,7 MJ. The results showed that the ideal level can be used is 15% with dry matter digestibility and the highest organic digestibility is 77.79 and 78.56%. The second stage is feeding U. lactuca flour 15% from total ration with different energy level for nine Bali weaned bulls with the purpose of knowing the level of intake and digestibility with treatment R1= 7.3 MJ; R2= 8 MJ; and R3= 8.7 MJ EM. The results showed that substitution of U. lactuca flour 15% had no negative effect on intake and digestion. The feed with 8 MJ energy ration had the same intake and digestibility value as 8.7 MJ but higher than the 7.3 MJ energy ration.