Pemanfaatan Protein pada Domba Lokal Jantan dengan Bobot Badan dan Aras Pemberian Pakan yang Berbeda

Abstract

ABSTRAK Penelitian bertujuan untuk mengkaji perbedaan pemanfaatan protein pada domba lokal jantan dengan bobot badan dan aras pemberian pakan yang berbeda. Penelitian dilaksanakan di Laboratorium Ternak Potong dan Kerja, Fakultas Peternakan, Universitas Diponegoro dari bulan Agustus hingga November 2009. Enam belas ekor domba lokal jantan yang terdiri dari 8 ekor dengan bobot badan (BB) rendah 10 ± 3,4 kg (CV = 8,89%), berumur 5-6 bulan, dan 8 ekor dengan BB tinggi 18 ± 3,8 kg (CV = 7,13%), berumur 9-12 bulan digunakan dalam penelitian ini. Penelitian dilakukan dengan menggunakan rancangan petak terbagi RAL dengan 4 ulangan. Pakan diberikan dalam bentuk complete feed sebanyak 2,4% dari BB untuk hidup pokok (HP) dan 3,6% untuk 1,5 kali hidup pokok (1,5HP). Pakan mengandung 92,11% BK; 12,9% protein kasar (PK); 1,86% LK; 22,48% SK; 42,13% BETN dan 14,66 kJ/g. Kebutuhan HP didapatkan dari pemeliharaan ternak tanpa pertambahan bobot badan selama periode adaptasi. Parameter yang diamati adalah konsumsi pakan, pemanfaatan konsumsi PK, kecernaan PK, retensi PK, nilai biologis protein (NBP), konsentrasi NH3 rumen dan urea darah serta produksi mikroba rumen. Hasil penelitian menunjukkan bahwa Kecernaan BK (%) tidak berbeda antara BB dan antar aras pemberian pakan (P>0,05), yaitu berkisar antara 50,03-51,41%. Kecernaan PK tidak berbeda antara BB dan aras pemberian pakan (P>0,05) dengan kisaran nilai 63,91-69,09%. PK termetabolis pada aras pemberian pakan 1,5xHP (17,61g/hr) nilainya lebih tinggi daripada 1xHP (8,31 g/hari) (P<0,05) namun tidak ada perbedaan yang nyata berdasarkan perbedaaan bobot badan. Tidak ada perbedaan nilai retensi PK dan NBP (P>0,05). Kisaran nilai retensi PK adalah 15,51%-24,22% dan NBP berkisar 24,11%-34,80%. Konsentrasi NH3 tidak berbeda antar BB dan antar aras pemberian pakan (P>0,05), yaitu pada jam ke 0 sebesar 140mgN/l dan pada 3 jam setelah pemberian pakan sebesar 147,5mgN/l. Konsentrasi urea darah pada 0 jam (4,51-4,78 mg/l), 3 jam (4,48-4,60 mg/l) dan 6 jam (4,40-4,89 mg/l) setelah pemberian pakan tidak berbeda antar BB dan antar aras pemberian pakan (P>0,05). Tidak terjadi perbedaan akibat perbedaan bobot badan dan aras pemberian pakan terhadap produksi nitrogen mikrobia (P>0,05). Berdasarkan hasil penelitian dapat disimpulkan bahwa pemanfaatan protein pada domba lokal jantan dengan bobot badan dan level pemberian pakan yang berbeda tidak berbeda. Kata kunci: pemanfaatan protein,domba lokal jantan,bobot badan, aras pakan Dietary Protein Utilisation by Indigenous Rams with Various Body Weight and Level of Feeding G. Mahesti, J. Achmadi and E. Rianto Master of Animal Science, Diponegoro University, Semarang ABSTRACK The objective of this experiment was to study dietary protein utilisation by rams with various body weight and level of feeding. This experiment was carried out at Laboratory of Meat and Drought Animal Science, Faculty of Animal Agriculture, Diponegoro University, from August to November 2007. Sixteen rams, consisting of 8 rams with average body weight (BW) of 10 ± 3.4 kg (CV = 8.89 %), 5-6 months old for light BW group, and 8 rams with average BW of 18 ± 3.8 kg (CV = 7.13%), 9-12 months for heavy BW group were used in this experiment. This experiment used splitplot design with 4 replications. The diet given contained 92.11% dry matter; 12.9% crude protein; 1.86% ethyl ether; 22.48% crude fibre; 42.13% nitrogen free extract and 14.66 kJ/g energy. It was offered as complete feed at 2.4% of BW for maintenance (1xM) and 3.6% of BW for 1.5 maintenance (1.5xM) feeding level. The 1xM feeding determined by maintaining the animals at zero body weight gain. The experimental variables measured were feed intake, protein utilisation, rumen NH3 concentration, blood urea concentration and microbial protein production. The results showed that dry matter digestibility (%) was not different between body weights (BW) and between feeding levels (P>0.05), ranged between 50.03 and 51.41%. Protein digestibility was not different between BWs and feeding levels (P>0.05), ranged between 63.91 and 69.09%. Metabolisable protein intake in 1.5xM (17.61 g/day) was higher than that in 1xM (8.31 g/day) (P<0.05), but there was no difference between BWs. There was no difference in protein utilisation which was represented by protein retention and biological value (NBV) (P>0.05). Protein retention ranged from 15.51 to 24.22% and NBV ranged from 24.11 to 34.80%. Concentration of NH3 was not different between BWs and between feeding levels (P>0.05). Rumen NH3 concentration at 0 hour before feeding is 140 mgN/l and at 3 hours after feeding was 147.5 mgN/l. Blood urea concentration at 0 (4.51–4.78 mg/l), at 3 (4.48–4.60 mg/l) and 6 hours (4.40–4.89 mg/l) after feeding was not different between BWs and between feeding levels (P>0.05). There was no difference between BWs and between feeding levels in microbial protein production (P>0.05). Based on results, it can be concluded that dietary protein utilisation in indigenous rams with different BW and feeding level was not different. Keywords : dietary protein utilsation, indigenous ram, body weight, level of feeding