Wanapat et al., 2000. Asian-Aust. J. Anim. Sci., 13 (4): 478
Whole cassava (Manihot esculenta) crop was harvested about 10-15 cm above ground 3 months after planting and sun-dried for 1-3 days or until the leaves were crispy dry and the branches and stems were mostly wilted to produce cassava hay. Cassava hay(CH) contained 86.3% DM, 8.9% ash, 23.6% CP, 44.3% NDF, 30.0% ADF, 5.8% acid detergent lignin, 0.257% condensed tannin and 0.35 mg % HCN, respectively. CH contained relatively higher amino acid contents than lucerne hay especially methionine, isoleucine, leucine and lysine. Ruminal fermentation of CH resulted in high concentrations of C2, C3 and C4 at 72, 17 and 7 mol/100 mole, respectively. A feeding trial was conducted to study the effects of feeding cassava hay in late lactating dairy cows fedon urea-treated rice straw during the dry season on their intake, ruminal pH, NH3-N, milk yield and compositions. Thirty Holstein-Friesian crossbred cows in their first lactation were randomly assigned in a randomized complete block design to receive five different dietary treatments: T1=supplementation of concentrate to milk yield at 1:2, T2=supplementation of concentrate to milk yield at 1:2+0.56 kg DM, T3=supplementation of concentrate to milk yield at 1:3+1.3 kg DM CH, T4=supplementation ofconcentrate to milk yield at 1:4+1.70 kg DM CH, T5=CH fed on ad libitum+small concentrate supplement. All cows received urea-treated rice straw as a roughage source throughout a 80-day feeding trial. Results showed that cassava hay contained high levels of protein and minimal levels of tannin at 3 months of harvest. Tannin intake ranged from 1.44 to 13.36 g/head daily and did not affect urea-treated rice straw intake. Milk yields across treatments were similar (5.4-6.3 kg/head daily) but 3.5% FCM was highest in cowswhich received CH at 1.70 kg/head daily. Feeding of cassava hay resulted in increasing milk fat (4.0 to 4.6%) (P<0.05) and milk protein (3.8 to 5.3%) (P<0.05). The use of CH could reduce concentrate supplementation to milk yieldfrom 1:2 to 1:4, respectively.