Abstract

The study was aimed at evaluating and improving cassava leaves (Manihot esculenta Crantz) and water spinach (Ipomoea aquatica) as protein sources in diets for pig production in small scale production systems in Cambodia. Four experiments were carried out with pigs using cassava leaves and water spinach as forage protein sources. In the first experiment (paper 1), eighteen crossbred castrated male pigs of 12.9 (±1.04) kg live weight were allocated to a 2*3 factorial arrangement of 6 treatments and 3 replications. The first factor was with or without DL-Methionine (Met) supplementation; the second factor was source of high protein forage including fresh water spinach (WS); fresh cassava leaves (FCL); and a mixture of the two proteins forages (WSFCL) [40:60 DM basis]. Pigs fed FCL as a main protein source had lower feed intake, live weight gain (LWG) and feed conversion ratio (FCR) than pigs fed WS or WSFCL (P<0.05). Supplementing Met to the diet did not affect LWG and FCR (P>0.05). In the second experiment (paper 2), twenty four crossbred castrated male pigs of 17.5 (±0.76) kg live weight were allocated to a 2*3 factorial arrangement of 6 treatments and 4 replications. The first factor was energy source from broken rice (BR) and a combination of rice bran (RB) with cassava root meal (CRM); the second factor was the combination between fresh water spinach (WS) and fresh cassava leaves (FCL) in proportions of 10:40, 20:30 and 30:20 in the diets, respectively. Pigs fed WSFCL (30:20) had higher feed intake, LWG and better FCR than WSFCL (20:30) and WSFCL (10:40) (P<0.05). Pigs fed RB and CRM as energy source had higher LWG and better FCR than BR (P<0.05). In the third experiment (paper 3), eighteen crossbred castrated male pigs of 24.5 (±0.84) kg live weight were allocated to a 2*3 factorial arrangement of 6 treatments and 3 replications. The first factor was with or without supplementation of DL-methionine and the second factor was methods of processing cassava leaves: ensiled (ECL), dried (DCL) and fresh (FLC). Feed intake was significantly higher for ECL than for DCL and FLC treatments (P<0.001). DL-methionine supplementation resulted in higher feed intake and LWG (P<0.05). However, there were no significant differences among cassava leaves processing methods in terms of LWG (P>0.05). The fourth experiment (paper 4) was arranged as a Latin-square design and included 4 crossbred castrate male pigs of 50.3 (±1.44) kg live weight. The pigs were fed randomly one of four diets based on rice bran, broken rice and fishmeal as the control diet (CTRL), and fresh water spinach (WS) or with fresh cassava leaves (FCL) or mixture with ratio 1:1 (WSFCL) as the main protein source. The DM intake was significantly higher for the CTRL diet than the others (P<0.05). Apparent organic matter, DM, CP, CF and NDF digestibility coefficients were significantly (P<0.05) higher for the WS than FCL and WSFCL treatments. The essential amino acid digestibility was higher for WS and CTRL than for WSFCL and FCL treatments. Nitrogen retention was higher for the CTRL than the WS diet, which were superior to diets WSFCL and FCL (P<0.05). In all experiments, there were no ill-health symptoms in any of the pigs that could have been ascribed to HCN toxicity arising from fresh cassava leaves. The average intake of HCN was 152 mg/day or 7.35 mg/kg live weight. There appeared to be an interaction between Met supplementation and protein sources from the forages for total DM and CP intake but no interaction for LWG and FCR. It is conclude that cassava leaves and water spinach could be used as protein sources for pig production in small scale production system in Cambodia.

chhayty.phdthesis