The use of mini round bales to evaluate the actions of fortifying solutions on poor quality roughages.

Abstract

358 Proc. Aust. Soc. Anim. Prod. Vol. 17 THE USE OF MINI ROUND BALES TO EVALUATE THE ACTIONS OF FORTIFYING SOLUTIONS ON POOR QUALITY ROUGHAGES P.B. Watson* , P.R. Martin**, C.J. Howitt*** and R.G.A. Stephenson** Mini round bales (1 kg) were used as a laboratory technique to simulate the effect that fortifying solutions may have on large round bales. Fortifying solutions containing urea, aqueous ammonia, sodium hydroxide, ammonium sulphate, x&asses, surfactants and urease were evaluated by assessing changes in in vitro dry matter digestion (IVD) of a poor quality hay. Significant increases in IVD occurred with solutions containing urea plus molasses (appprox. ll%), and sodium hydroxide (13.3 and 22.4% for 2 and 44 w/w respectively). Recovery of added nitrogen was high (> 90%) except for the solution containing urease. Mini bales have the potential to be developed as a suitable proxy for large round bales. Keywords: mini bales, fortifying solutions, in vitro digestion, roughage. INTRODUCTION Native pastures and cereal stubbles require economical and practical treatments to useful animal feedstuffs. Stephenson et al. (1984) have shown that voluntary feed intake and dry matter digestion o f LOW quality hay 'by sheep iI;iprove when the baled hay is fortified with a nitrogen-rich solution. Fortification of baled hay provides not only additional nitrogen, but also a suitable microenvironment for 'bacterial and fungal growth (Seal and Kelley 1980). In addition, basic fortifying solutions can break down lignifieti matrices (Lawlor and Shea 1979). These actions can increase the availability of digestible carbohydrates to ruminants. Various fortifying solutions and storage periods were investigated using mini round bales as a laboratory technique for evaluating dry matter digestibility of poor quality pasture hay after treatment. The current economic constraints of the Queensland sheep industry were considered when the type and quantity of ingredient were evaluated in the fortifying solutions. Iilake MATERIALS AND filETHODS Three experiments were conducted to assess the effectiveness of fortifying solutions on mini round bales. In experiment 1, Flinders grass chaff was weighed into 1 kg lots before being compressed into 150 mm diameter x 260 mm mini round bales of a higher density than most large round bales. The chaff was held as a bale within a 250 x 370 mm paper envelope. The mini bales were fortified with various solutions (Table 1) via a 150 mm x 2 mm hypodermic needle inserted in 11 places at each end of the bale to mimic the practical 'spear' technique used on large round bales (Stephenson et al. 1984). Solution 8 included 0.9 g Jack Bean Meal which contained sufficient urease enzyme to convert half the added urea to ammonia. Equal parts of two non-ionic surfactants were added to solutions 6 and 7 in an attempt to achieve more uniform wetting and distribution of the solution throughout the bale. The quantity of water used was restricted because of ** *** * 12 Garvary Street, Holland Park, Brisbane, (2. 4121. Animal Research Institute, 665 Fairfield Road, Yeerongpilly, Q. 4105. Department of Primary Industries, GPO Box 46, Brisbane, Q. 40Gl. Proc. Aust. Soc. Anim. Prod. Vol. 17 359 practical poblem with higher volumes associated with uneven distribution within, and loss of soix solution from, the bale. These problems cm also occur with large round bales fortified under industry conditions (Stegjhenson unpublished data). Bales were sampled iilmediately or stored for 10 or 30 days in a warm (1830�C), dry environzicnt. TABLE 1 Ingredients added to 1 i;s mini round bales of FlinZers grass chaff in experiment 1 before storage and analysis (I;') In experiment 2, poor quality Rhodes grass chaff was weighed into 1 kg lots which were then sprayed with the fortifying solution (Table 2) before being compressed into mini round bales. This method was used to achieve a uniform application of the solution. Bales were samsled immediately or stored for 20 days in a warm, cry environment before being sampled. TABLE 2 Ingredients added to 1 kg mini round bales of Rhodes grass chaff in experiment 2 before storage and analysis (g) Experiment 3 was designed to quantify and compare the caustic action of sodium Again, 1 kg hydroxide on in vitro dry matter digestion (IVD) of Rhodes grass. lots of hay wer-c s,rrayed with the fortifying solution before being coqxesseti into mini round bales. The fortifying solutions were 5% water, 5% water plus 2% NaOII, and 5% water plus 4% HaOH. The bales were stored in a warm, dry environment for 1 or 21 days. In each experiment, fortifying solutions were randomly allocated to bales, with each solution being replicated twice. Before sampling, bales were broken open and mixed thoroughly, and two samples were taken for analysis of nitrogen (IC) content. After sampling, the hay from the broken bale was sealed in a plastic bag and 360 Proc. Aust. Soc. Anim. Prod. VoZ. 17 frozen. Tit the end of each ex;)eri;;lent period, the hay was taken from cold storage and hamzermilled through a 1 mm screen for analysis of in vitro cigestion of dry matter (!G.nson and liclaod 1972). Two samples were useci for each IVD analysis. Statistical analysis of % IVD anci & increase in ND from the basal level for esperic,ents 1, 2 arid 3, and of 2 recovery of added 11 in exiJerirnent 1 was by analysis of variance. XESULTS In eqeriment 1 there were ci:nificant iifferences (P < 0.05) between fortifying solutions for % IVD and % increase in ND (Table 3). Bales stored for 30 Cays had significantly greater (P < 0.01) 8 IVD and % increase in IVD (40.7 LO.33 and 15.3 + 0.93, mean +_-kZ respectively) then bales stored for 10 days (3S.2 and 8.3) and 0 days (36.7 and 4.2). Table 3 Percentage IVD and percentage increase over basal level (e:;periment 1) In experiment 2, there were siyniiicant differences (P ( 0.05) between fortifying solutions for % IVD and % increase in IVG (Table 4). Xolasses (solution 2), and 4% urea arid molasses mix (solution 6) had the greatest effect on % IVD. Bales stored for 20 days had significantly higher (P < 0.05) 8 XVD and % increase in IVD (46.0 + 0.3s and 10.1 +,- 0.91 respectively) than those stored for 0 days (44.4 anti 6.3). Table 4 Percentage IVD and percentage increase over basal level (experiment 2) In experiment 3, there were significant differences (P < 0.05) between fortifying solutions for % IVD and % increase in IVD (Table S), with the 4% XaOH solution having the greatest effect. There were no significant differences (P > 0.05) between storage periods. Proc. Aust. Soc. Anim. Prod. Vol. 17 Table 5 361 Percentage IVD and ;=ercentage increase over basal level (experiment 3) in exgerirncnt 1 the % recovery of added M showed a significant (P < 0.05) interaction between fortifying solutions and storage period. This was due to the urease additive in solution 8 significantly decreasing the recovery of 11 at days 10 and 30 of storage. Al.1 other solutions had a recovery >90%. A similar result occurred in experiment 2. -a DlSCUSSIOlG This study using ii1 i n i round bales has shown that fortifying solutions significantly affect the IVD of treated hay. While 43 I<aOii in experiment 3 had the greatest effect (22.4% increase), the 2% NaOH (13.3% increase) was similar in effect to the 2% urea and 10% molasses solutions (approx. 11% increase) in The additional fortification additives (aqueous ammonia, experiments 1 and 2. surfactants and higher levels of urea) did not increase IVD. These additives may have had greater effect if the quantity of water had been doubled to a total similar to that used in the alkalage procedure of 150 ml/kg (Kellaway et al. 1980). Unpublished data suggest that changes to the den4C;ity of bales &o not The acZitic\n of urease t0 a fortifying solution in czperinent 1 affect IVD. significmtly GecresseG nilrogen recovery. It is suggested that the generalLy sl.iall chaqes in IVD in e,qeri;nents 1 and 2 indicate that very little caustic action occurreti. This could be due to the sr~ll amounts of free ammonia which, being a weak base in contrast to sodium hydroxide, had minimal effect on liynified plant matrices. Larger changes in digestibility could be expected in vivo because the extra nutrients (Lu and minerals) would enhance rumen microbial activity. The use of mini balev in the laboratory as proxy for large round bales > 300 kg has the potential for evaluating fortifying solutions at reduced costs and with more replications. REFERENCES T.C., DUNLOP, A., RYAN, I?., SRISKAXDARAJAH, N. and LEIXOLZ, Jane (1980). Proc. Aust. Soc. Anim. Prod. 13: 257. LAFJLOR, H.J. and SHEA, J.O. (1979). AnimFeed Sci. Technol. 4(4): 169. MINSON, D.T. and HcLEOD, M.N. (1972). Div. of Tropical Pastur!, Tech. Paper MO. 8, CSIRO, Aust. SEAL, K.J. and KELLEY, J. (1980). In 'Proceedings of the 4th International Biodegradation Symposium, Berlin, p. 241, editors Oxley, Bechner and Allsoyp. (Pitmans: London). STEPFiENSOU, R.G.A., PRITCHARD, D.A. and CONNELL, J.A. (1984). Proc. Aust. Soc. Anim. Prod. 15: 604. KELLAi;lAY ,