Abstract:
J.A. LIWDSAY* a;nd I.D. L()xTO~T* Tropi~r'l native pastures rapidly decline in di:yestibility and nitrogen (N) conten$ with the onset of the dry season. Nitrogen supple- _ mentatian is offered as a management strategy to overcom the dry sea.son nutritional deficit, Xost of the tropical research on N supplements h&s been with protein meals of unknown degradabili.Ly or with urea, The wor1: of Kenpton and'Leng (1979) yrith 10~7 quality forage and proteins of known degradability,has 'stimulated interest in simil;:r ~:ork ~5th cattle fed 'tropical forage diets. Native pa'sture hay (predominantly HeteropotTn contortus) containing 0.4s N was chaffed ad fed ad li,bitum t;~ steers of 170 kg liveweight held in pens. In the first &periment supplements of 40 Q N as urea plus sulphur (US) or formaldehyde casein (E'C) aid WtFC were offered. . Animals offered.the contro3. diet (1TP) lost 28'1, g li.vemj &.t; per. daY _ v3e-f whereas the Wand FC supplemented animalL.) US+FC was fed these aninta.l.s gained. 131 g ,per d.s'+ cc TIGXbki~C?C~ .* *'~jlt Cd , :ql e n In a seconc? CZpH5TIieY~i using si.r~ilx.- steers ax1 the sE?m? lxl,s~,l diet the US and US+FC treatments 'Gere compared ~i.th a supplenlc:lA oZ 500 g of a mixture (PP) containing meat st~zd bone mec71, fish MXI- and fcx:rx.ldehyde-treated cottonse ed meal in the ratio 1:1:8 (Hennescy, 3.978). Table 1 gives the results from experiment 2. , The control aniF);& lost weight at a faster rate, th.zn in experimexrt 1 and f!edi.ng US md US+FC merely red.uded. the live-mQ;ht loss. However9 mpplenents of protected' protein (FP) or PP plus US prod~~&i. z liveweight &sin. c These txo exper5.men-L have demnstra.ted a livewi~ht zxsponse to the supplem&tation of tropicz.1 'forakge diets wil3' protected pmteins. The inclusion of urea xi11 give zn added.'response but the benefit of PP alone may be ~nerally sufficient `uVl[1en poor qucckity pasture is availa~~le. . . The PP mixture has the a.dvarxtagE of being palatable and yjithout a toxicity risk. Annual Research Report Agric. Res. St. Grafton: HmEmEXX, D.7.' mTmCN, T.J. and LEEG, R.A. (1979)* Br. J. ?Mx. t~-t289-302. ( 1 9 7 8 ) . _ ,-p-m--._-e