Effect of supplements of molasses and urea on intake and digestibility of native pasture hay by steers

Abstract

Ten steers (five Shorthorns and five Brahman crossbreds) were individually housed in digestibility crates and fed low quality native pasture hay (0.47 per cent N) with the following supplements-1 . nil ; 2. molasses ; 3. urea ; 4. urea-molasses ; 5. urea-molasses. The hay was fed ad libitum except in treatment 5 where it was fed at the same level of roughage intake as in treatment 2. Intake and digestibility were recorded.Treatments 2, 3 and 4 had roughage dry matter intakes 27.8 per cent, 14.6 per cent and 65.4 per cent respectively greater than the hay alone group. There was no significant effect of treatment compared with the control group on the apparent digestibility of dry matter or organic matter, but the apparent digestibility of crude protein was significantly improved by a supplement containing urea. There was no effect of breed on apparent digestibility of dry matter, organic matter or crude protein but Brahman crossbreds consumed 20.0 per cent more dry matter than Shorthorns after intakes had been corrected for metabolic size.T h e practice of using urea as a nitrogen supplement fed through roller drum lickers (Mutch 1966) with water and molasses as carriers is now generally accepted in north Queensland (Condon, Smith and Winks 1970). Despite this, there is little information from controlled experiments on the effect of ureamolasses supplements on the utilization of low quality roughage diets by cattle. Experiments by Winks, Alexander and Lynch (1970) with grazing weaner cattle during the dry season have shown a significant improvement in liveweight performance. Based on measurements offaecal output these authors concluded that there was a greater intake of dry matter by cattle supplemented with urea-molasses than by unsupplemented cattle. I n the work described in this paper the two predominant breeds of cattle (Shorthorns and Brahman crossbreds) in north Queensland were fed a diet of native pasture hay plus a supplement. The hay was typical of the forage available in the spear grass region of north Queensland during the dry season.The aims were to determine the intake of D.M. and the digestibility ofthe D.M., O.M., C.P. of the hay and the effect on these factors of supplements of urea and molasses. This information would help to explain the deductions by Winks, Alexander and Lynch (1970) concerning intake based on fae.ca1 outputs lacking in field experiments but which can be provided by this experimental approach. Further, some clarification of the effects of urea-molasses on digestibility of low quality diets within a tropical environment and with tropical breeds of cattle is warranted. Materials and methods HayThe hay used was cut from a selected area of native pasture at Millaroo, 760 km south of Townsville. The pasture was growing on an Oakey soil (Christian et al. 1953), and was harvested after maturity in April 1970.The Authors-Mr. A. J. Ernst, Department of Primav Industries

Influence of Soybean Meal and Sorghum Grain Supplementation on Intake, Digesta Kinetics, Ruminal Fermentation, Site and Extent of Digestion and Microbial Protein Synthesis in Beef Steers Grazing Blue Grama Rangeland

“…As a result of the techniques used to estimate forage intake, total tract OM digestion coefficients were a function of forage and supplement IVOMD estimates. In contrast to present results, Ernst et al (1975) reported no effects of supplemental protein or energy on DM or OM digestibilities of low-quality hay. Likewise, Rittenhouse et al (1970) reported little effect of protein, and no effect of energy supplementation, on forage DM digestibility.…”

“…These results agree with those of McCollum and Gaiyean (1985) and Judkins et al (1985) with regard to protein supplementation and Branine and Galyean (1985) for grain supplementation. Ernst et al (1975) reported no effect of supplemental protein or energy on DM or OM digestibility in steers consuming native pasture hay.…”

Effects of Amount of Concentrate Supplement on Forage Intake, Diet Digestibility and Live Weight Gain in Yellow Cattle in Vietnam

“…The apparent increase in forage intake at the lowest amount of supplement consumed was likely to be due to the supply of nutrients that were limiting digestion in the rumen or tissue metabolism when the forages were fed alone (see Doyle, 1987). These positive effects of small amounts of supplement on intake of low and medium quality forages have been reported elsewhere (Cohen, 1974;Ernst et al, 1975;Lee et al, 1987), although such effects are not always found (Hennessy and Murrison, 1982;Hennessy et al, 1983;Smith and Warren, 1986). The feeding management used, restricted access to grass during the day and ad libitum feeding of straw at night, may have constrained the complementary effect of low amounts of the supplement on forage intake.…”

Effect of concentrate supplementation on nutrient digestibility and growth of Brahman crossbred cattle fed a basal diet of grass and rice straw

“…In our study, there was no increase in Guinea grass intake at the lowest level of concentrate supplementation, because all of the offered grass was consumed. The positive effects of small amounts of supplement on intake of low and medium quality forages have been reported elsewhere [ 14 , 18 , 19 ]. However, with increasing concentrate, substitution invariably occurs [ 20 ] and increases as the amount of concentrate consumed increases [ 2 ].…”