The place of solidified molasses blocks in the grazing industry.

Abstract

149 THE PLACE OF SOLIDIFIED MOLASSES BLOCKS IN THE GRAZING INDUSTRY C.A. GRAHAM ICI Australia Limited INTRODUCTION Molasses, a liquid by-product from sugar manufacture, is very palatable to ruminants and readily consumed by grazing animals. As well as being palatable, it contains adequate levels of energy, sulphur and other trace minerals (NRC 1964) and is relatively cheap, $23/tonne in 1977, (CSR personal communication). Despite its availability and cheapness, molasses has not been used widely as a stock feed. It was not until a satisfactory low cost method of onfarm feeding was developed (Mutch 1966) that the usage of molasses increased. Between 1967 and 1974 stock food usage rose sharply from 38,000 tonnes to 101,000 tonnes (ABS 1976). This sharp increase in molasses usage coincided with widespread acceptance in Queensland of feeding urea/molasses mixture in roller drum lickers (Queensland Department of Primary Industries 1969 - 70). More recently, increasing on-farm labour costs together with a reduction in the availability of farm labour has stimulated commercial interests in developing molasses blocks as an alternative to liquid molasses supplements. I would like to describe some experimental work involving molasses blocks in bloat control in Southern Australia and the preliminary work onphosphate molasses blocks in Northern Australia. Bloat Bloat is caused by a persistent foam in the rumen inhibiting belching of entrapped gases (CSIRO 1972). It occurs commonly in beef and dairy cattle grazing legume dominant pastures in temperate Australia. The accepted method of control is to remove or prevent foam formation with an antifoaming agent. Twice daily drenching is the most effective method available for dairy cattle. For beef cattle, however, the most practical control measures depend upon free choice systems using pluronic detergent. The effectiveness of these methods has been variable (Langlands and Holmes 1975). The discovery by Laby (1972) of a more effective and palatable detergent than used previously provides the opportunity of improving free choice methods. I would like to present the results of 12 field trials which were designed to assess the effectiveness of an alcohol ethoxylate detergent (Teric 12A23B) incorporated in a palatable molasses feed block. Eight grazing experiments were conducted in Victoria between 1973 and 1976 (Graham, P@rn and Linehan (1977), Pern, Walsh and Graham (1977) unpublished data) and four in New Zealand during 1976 (Barr and Graham 1977 unpublished data). 150 Trial procedure Properties were-selected for trial work on the basis of prior bloat problems. In most experiments a uniform area of pasture was equally divided by an electric fence. In experiments 1-3 and 9-12 the animals allotted to one half were supplied with bloat blocks. In experiments 4-8 placebo and bloat blocks were used in a cross over design. After a period of 1-2 weeks the blocks were weighed and interchanged between groups. The operator responsible for bloat scoring did not know which set of blocks contained the active ingredient. The blocks were placed in resting areas used by the cattle, unprotected from rain. Scoring method The method used animal with only the left both flanks were distended it was given a score of 2. or manager of the property has been described by Laby (1972). An flank distended was scored as I, and if and the animal showed signs of distress All scoring was made daily by the owner on which the experiment was done. The bloat scores recorded in each preliminary period of 1-2 weeks were used to divide the animals into two groups of equal bloat susceptibility. Block composition Although different block formulations were used there was no significant formulation effect. Composition of the blocks are given in Table 1 for completeness. Formulations l-4 were all tested in experiments l-3 while formulations 2 and 5 (placebo) were used in experiments 4-8. Only formulation 2 was used in experiments 9-12. TABLE 1 - Percentage composition of solidified molasses blocks Bloat Frequency and Severity The results of 12 grazing experiments conducted in widely varying geographical areas show that bloat blocks consistently reduce bloat frequency (Tables 2, 3 and 4). TABLE 2 - 1973 Bloat block trials - NE Victoria. Table 3 Dloat and Placebo Dlock Trials TABLE 4 - New Zealand Trials 1976. 154 In eight of the 12 trials where moderate to serve bloat occurred block supplementation significantly reduced bloat frequency. Under severe bloat conditions (trials 1, 9 and 12) both bloat severity and frequency were reduced. The almost complete absence of severe bloat in these three experiments is in contrast with the results obtained using capsules (Laby, personal communication) where severe bloat was reduced but not eliminated. The effectiveness of these blocks appears to be due to a number of factors including a high detergent intake. High intakes of alcohol enthoxylate detergents persist in the rumen for long periods. Laby (1972) found that a single dose of 28 g of Teric detergent persisted in the rumen of non-lactating dairy cows for 44.5 hours. Persistence was measured at the time interval between dosing and the re-appearance of blo_al. Hpwever in most situations a mean Teric intake of 10 g head day- is recommended In trials l-7 the mean teric intake L'f ~;e~e~th',,'~~~d~~SfR~a~g:~~,e th ret mmended level but the mean . -7 -P intake was reduced to 11.2 g head day in the trials 8-12 by increasing the ratio of blocks to animals (Table 5). TABLE 5 - Effect of block to animal ratio on Teric consumption. Liveweight Significant liveweight increases were observed in five grazing trials (1, 4, 7, 9, 11). Part of this increase in liveweight may be due to differences in gut fill brought about by differences in the density of the contents. The rumen content of bloated animals are known to be less dense than non-bloated animals (Laby 1972). It is unlikely that the molasses component of the bloat blocks made any significant contribution to weight gains. Where both placebo and bloat blocks were used, which have a similar molasses content, weight increases were consistently greater for the bloat blocks. Mortality 10 animals died was withdrawn and treated of death occurring. All control groups. In Trial in the 12 field trials while one animal from Trial 7 because of the probability the mortalities were recorded in the 9 it was found necessary to give 244 155 bloat drenches in the control group to treat bloat while only one drench was given in the block group. Proportion of Animals Consuming Bloat Blocks A successful free choice method of bloat control depends not only upon the level of Teric intake but also on the proportion of animals consuming the supplement and the within and between day variation in intake. In two trials where individual block consumption was measured using the isotope method described by Nolan et al (1975) 10 out of 11 animals consumed the supplement in one trial while eighteen out of nineteen animals consumed the blocks in the second trial (Table 6). TABLE 6 - Assessment of Individual Teric Consumption. 156 In both trials more than 80% of the animals consumed an effective or near effective dose level. Pattern of Consumption Maintaining adequate concentrations of detergent in the rumen is essential for achieving effective bloat control (CSIRO 1972). The frequency of daily visits to the block will therefore be important in maintaining these levels. Where daily patterns of block consumption were monitored (Table 6) using a surveillance camera it was found that three-quarters of the animals visited the block daily while more than half of the animals made multiple daily visits to the block. The combined findings of a large proportion of animals taking an effective or near effective dose level with a high frequency of multiple visits further suggests that Teric bloat blocks will reduce the incidence of bloat. SUMMARY The results .of these field trials suggest that Teric Molasses blocks will be useful in reducing the incidence and severity of bloat particularly for beef cattle where no satisfactory alternative method for individual treatment is yet available. PHOSPHATE SUPPLEMENTS In northern Australia there is an opportunity to develop a palatable phosphorus supplement for beef cattle. Research work has shown the need for a phosphorus supplement for growing and breeding cattle (Winks et al 1976, Holroyd et al 1976). However when phosphoric acid was used as part of a liquid molasses supplement animal performance was depressed (Playne 1974). Alternative solid phosphate/salt supplements are not readily accepted by cattle when the P requirement is greatest. over the wet summer months causing further economic loss to the beef producer. Methoprene, an insect growth regulator, has been incorporated in salt blocks in USA and successfully fed (Harris, Chamberlain and Frazer 1974) to range cattle to reduce numbers of the horn fly (H.irritans irritans), a sub-species of buffalo fly. The possibility of treating both phosphorus deficiency and controlling buffalo fly has wide practical appeal. However the difficulty and cost of demonstrating a definitive field response to both phosphorus supplementation and buffalo fly control in the field is well recognised. Despite these difficulties several field experiments have commenced to examine the acceptance and variation in consumption of a phosphate molasses block and to assess the effects of methoprene on buffalo fly population and on beneficial insects such as the dung The initial results on animal beetle (Onthophagus gazella). acceptance of a dicalcium/molasses block are encouraging. (Haemtobia irritans exigua) increases to significant proportions In addition to phosphorus deficiency problems, buffalo fly 158 In a field experiment completed at Department of Primary Industries 'Swans Lagoon' Cattle Field Research Station, North Queensland, dicalcium phosphate/molasses blocks (7.2%P) were readily accepted by 20 yearling Brahman X Shorthorn heifers over a 4 month period (Gallagher et a2 1977). All animals accepted fpe blfcks with individual intakes ranging from 2 - 150 g head day- . There was also a significant increase in plasma inorganic P with supplement intake. In a pen experiment, methoprene was includ_ef in-tlh;t;ziiyn of mature animal at-ievels ranging from 0.001 mg kg day -H uptol.Omgkg day . Samples of dung were seeded with fly eggs in the laboratory. There was a 97.5% mortality in the buff_a$o fly larvae at the lowest ,rate and 100% mortality at 0.025 mg kg (Stubbs, personal communication). Where dung beetles wgfe reared in the same dung there was no effect at thy 0.025 mg kg level. However at 40 times this level (1.0 mg kg ) there was a 38% reduction in progeny in the first beetle generation. Dung was also collected in the field from grazing cattle supplemented with phosphate blocks containing 0.01% methoprene. There was an 89% inhibition of larvae development compared with the control in laboratory assay. However after 5 weeks this was not reflected in any significant reduction in the adult fly numbers in the field. This lack of response may be due to migration of flies from adjacent, untreated animals swamping the treatment effects. This grazing experiment is continuing. Although it is too early to predict the final outcome of this work it does appear at this stage that the phosphate/molasses block may be a satisfactory P supplement for feeding cattle during the wet season. Further work still needs to be carried out on the extent of migration of buffalo flies between mobs of cattle before making any confident prediction of the likely success or otherwise of suppressing buffalo fly breeding by incorporating methoprene into the supplement. However methoprene blocks are more likely to succeed under extensive grazing conditions where there are large distances between mobs of cattle and where the effects of migration of adult buffalo fly should be minimal. CONCLUSION The tritiated water technique developed by Nolan et al now provides a more accurate assessment of individual supplement intake, . which allows for a better assessment of the potential of free choice systems for the grazing industry. Research into the behavioural aspects of free choice supplements may in the future enable producers to reduce the variation in intake currently being experienced and therefore further improve responses. REFERENCES Australian Bureau of Statistics (1975-76) Overseas Trade. Part 1 Exports, 13. C.S.I.R.O. (1972) - Rural Research 78:2. Gallagher, B., Holroyd, R.G., Graham, C.A. and Murray, R.M. (1977). Pet. &act. (March)30. 159 Graham, C.A., Pern, C. and Linehan, R.L. (1977). Agric. Anim. Hus. (in press). Aust. J, Exp. Harris, R.L., Chamberlain, W.F. and Fraser, D.E. (1974). J. Econ. En-to. 67~384. Holroyd, R.G., Allen, P.J. and O'Rourke, P.K. (1977). Aust. J. Exp. Agric. Anim. Hus. (in press). Laby, R.H. (1972). Wool Technology and Sheep Breeding 19:59. Langlands, J.P. and Holmes, C.R. (1975). Aust. J. Exp. Agri. Anim. Hus. 15~5. Mutch, C.B. (1966). &Id. Agric. J. 92:630. National Research Council (1964). Tables of Feed Composition Publication 1232. Nat. Acad. Sc.:Washington. Nolan, J.V., Norton, B.W., Murray, R.M., Ball, F.M., Roseby, F.B., Rohan-Jones, W., Hill, M.K. and Leng, R.A. (1975). J. Agric. Sci., Camb. 84:39. Playne, M.J. (1974) - Proc. Aust. Soc. 1O:lll. Queensland Department of Primary Industries Annual Report (1969-70).