การประเมินความต้องการโปรตีนของแพะพันธุ์พื้นเมืองไทยที่ใช้ใบปาล์มน้ำมันเป็นแหล่งอาหารหยาบหลัก

Abstract

The objective of this study was to evaluate effects of various crude protein (CP) levels using oil palm leaflets as the main roughage source in total mixed ration (TMR) on productive performance of goats. Sixteen Thai native male goats with initial weights 15.02±1.5 kg and 8-10 months old were assigned to four groups using completely randomized design (CRD). Four dietary treatments consisted of 9.0, 12.0, 15.0 and 18.0% CP levels (T1, T2, T3 and T4, respectively). Animals were fed dietary treatments twice daily in equal parts throughout the 180-d experimental period. Rumen fluids and blood sample were collected at 0, 2 and 4 h after morning feeding prior further analysis. The dry matter intake (DMI) was lowest (p<0.05) in animals fed a T1 diet compared to the rest of three treatments. DMI was increased with the increasing CP levels from 60.62 in T1 to 121.20 g/h/d in T4 diet. Similar trend was observed for fecal N as increased with the increasing CP level in goats fed T1 to T4 diet. Urinary N excretion was highest in animals fed T3 (8.81), whilst lowest was in T2 (4.82 g/h/d) diet. N absorbed and N retention had significantly higher (p<0.05) in animals fed T3 than those fed the other treatments. Ammonia nitrogen (NH3-N) concentration was highest in goats receiving T4 (145.0 mg/L). Blood urea nitrogen (BUN) was increased with increasing CP level from T1 (2.77) to T4 (10.59 mmol/L). Improvement of average daily gain were 35.56 and 66.49 g/h/d (equivalent to 86.98%), when animals fed T1 and T4, respectively. The highest revenue was 474.82 Baht/h during 180-days experimental period in goats fed with T3. Results from this study indicate that the formulated 15.0% CP level using oil palm leaflets as main roughage sources in TMR diet is optimal productive performance and economic return for growing native meat goats.