Study On The Pelletized Rice Straw-based Total Mixed Ration(TMR) For Growing Goats

This study was conducted to evaluate the effect of pretreatment and pelletization on nutritive value of rice straw (RS)-based total mixed ration (TMR), and to investigate growth performance, carcass traits and meat quality of growing Boer goats fed on the TMRs.In Trial 1. an original linear programming was used to design the least costing formulation of RS-TMR according to NRC (1981). Six TMRs were processed: (1) uu-TMR ( unpelletized and unpretreated ), (2) pu-TMR ( pelletized but unpretreated ), (3) uto-TMR ( unpelletized but pretreated with Oh reaction time ), (4) pt0-TMR ( pelletized and pretreated with Oh reaction time ), (5) ut48-TMR ( unpelletized but pretreated with 48h reaction time ), (6) pt48-TMR ( pelletized and pretreated with 48h reaction time ). For all the TMRs, roughage-concentrate ratio was at 60:40 ( w/w, DM basis ). In vitro gas production (GP) test was performed to evaluate the nutritive value of the RS-TMRs. The potential GP of six TMRs showed the similar trend to the GP, and the rate of GP (c) reached the highest during the time from 12h to 24h. The GP at 24h were significantly higher in pt48-TMR than that in other TMRs (P<0.01). The estimated in vitro organic matter digestibility (OMD) and metabolizable energy (ME) content increased significantly owing to alkali treatment (P<0.01) of RS andpelletization (P<0.01) of TMR, and a positive additive effect (P<0.01~) between alkali treatment and pelletization was observed in GP. OMD, and ME for pt0-TMR. In comparison with Oh reaction time, 48h reaction time had a positive effect on the GP, OMD. and ME of unpelletized RS-TMRs, and increased significantly the GP, OMD, and ME of palletized RS-TMRs (P<0.01}. Microbial protein yield increased with alkali treatment of RS (P<0.01), but pelletization and reaction time exerted little effect on it. It is inferred that pelletization, alkali treatment and the effective reaction time improved the nutritive value of RS-TMR, and pt48-TMR is the optimal diet for ruminant feeding among the six TMRs in the current study.In Trial 2, the effect of zinc-methionine (Zn-Met) on the nutritive value of RS-TMR was evaluated by In vitro GP techniques. Four levels (0, 0.12, 0.24, and 0.36%) of Zn-Met were supplemented into the basal diet (pt4g-TMR). There was a positive correlation between the Zn-Met level and In vitro GP. However there was no significant difference between the levels of 0.12. 0.24, and 0.36%, which might be due to the relative insufficient supplementation of Zn-Met. In consideration of the lowest cost of feed, pt48-TMR with 0.12% Zn-Met was selected for ruminant feeding in this study.In Trial 3, thirty-six growing Boer goats were divided into three equal groups and randomly allocated to receive one of the following diets: (1) unpelletized ryegrass hay-based TMR (TMR I ), (2) pt48-TMR in Trial 1 (TMR II), and (3) pt48-TMR plus 0.12% zinc-methionine (TMRIII). The experimental period lasted 75 days with the first 15 days for adaptation. On the final day of the feeding trial, blood samples were obtained by jugular venipuncture before the morning feeding to measure serum biochemical parameters. Feed intake, average daily gain and feed conversion ratio were significantly higher (P<0.01) in TMR II and TMRIII than in TMR I , with little difference between TMR II and TMRIII (P>0.05}. Concentrations of total protein (P<0.05), albumin (P<0.01), glucose (P<0.01), Ca (P0.05} between TMRII and TMRIII. It is concluded that pt48-TMR was in favor of improvement of the growth performance of Boer goats, and supplementation of 0.12% Zn-Met had no significant effect on it.In Trial 4, because of little differences in growth performance and serum biochemical parameters between TMR II and TMRIII,...