Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 19 HOMINY BASED CONCENTRATE AS A SUPPLEMENT FOR GRAZING DAIRY COWS W. K. EHRLICHA, R. J. MOSSA, J. ANSELLA and P. MARTIN AQDPI, Mutdapilly Research Station, M/S 825, Ipswich, Qld 4305. BQDPI, Animal Research Institute, Yeerongpilly, Qld 4105. B SUMMARY Hominy is a byproduct of maize grain processing and was evaluated as the basis of a supplement for dairy cows grazing tropical pastures. Twenty-four Holstein Friesian cows in mid to late lactation were given supplements once per day of either 5 kg of a 60% hominy based dairy pellet or 5 kg of rolled sorghum plus minerals over a 12-week period. Cows ate all the hominy supplement after a short adjustment period. Milk yields averaged 12.9 L/day with hominy pellets and 11.5 L/day with sorghum (P < 0.05). Protein yield averaged 0.40 kg/day and 0.36 kg/day (P c 0.05) and lactose yield 0.61 kg/day and 0.53 kg/day (P c 0.05) for hominy pellets and sorghum respectively. Butterfat percentage tended to be lower with the feeding of hominy pellets, at 3.7 v. 4.1% (P < 0. 10), but butterfat yields were similar at 0.47 kg/day for hominy pellet and sorghum respectively. Liveweight loss was similar for both treatments. We conclude that hominy pellets can replace sorghum grain and increased total milk, protein, and lactose yields while maintaining butterfat and protein percentages at an acceptable level in this situation. Keywords: hominy, sorghum, grazing, dairy cows. INTRODUCTION Milk production is limited by low nutrient content of tropical pastures and concentrates are fed to increase production (Cowan et al. 1977). Hominy is now available as an alternative concentrate to cereal grain. It is a byproduct of corn grits manufacture and consists of the skin and germ and a small amount of endosperm from the maize seed. It has a high oil content of 9.9%, a relatively high metabolizable energy content of 14.1 MJ/kg and a medium protein content of 10.9%. The product is being marketed as a base for a concentrate pellet due to the difficulty of augering the raw material. This experiment was conducted to compare the milk yield of cows consuming a hominy based concentrate pellet with that of cows given cracked sorghum grain plus minerals. MATERIALS AND METHODS The experiment was carried out on Mutdapilly Research Station in south-east Queensland 46 s; (lat. 27' ' long. 152'40'E) for 12 weeks from March to June 1991. Cows grazed as 1 group at a stocking rate of approximately 5 cows/ha on irrigated Rhodes grass (Chloris gayana) and pangola grass (Digitaria eriantha ssp. pentzii). Hominy pellets were obtained in 1 batch from a commercial supplier. The concentrate formulations are shown in Table 1. An estimate of ME content of supplements was made using the formula of Oddy et al. (1983). Table 1. Concentrate formulations (% as fed) Twenty-four multiparous Holstein Friesian cows in mid to late lactation were blocked in pairs on the basis of calving date and milk yield over 2 weeks prior to commencement of the experiment. They were then randomly allocated to 2 treatments. All cows received 5 kg of cracked sorghum daily prior to the start of the experiment and 5 kg of either hominy or sorghum during the 12-week feeding period. Cows were adapted to hominy pellets by gradually increasing the pellets and reducing the sorghum until all sorghum was removed after 1 week. Cows were individually fed after morning milking. There were no refusals of concentrate after the first week of the experiment. Supplement degradability was measured 103 Proc. Aust. Sot. Anim. Prod. Vol. 19 in sacco (Mehrez and Orskov 1977) using three rumen-fistulated Hereford steers fed a maintenance diet of grassy luceme hay (Medicago sativa) with a crude protein content of 19%. Cows were milked twice daily, and yield recorded on 2 consecutive milkings each week. A composite sample of evening and morning milk was analysed for butterfat, protein and lactose content (Milkotester Mk III - Foss Electric). In week 12 a composite milk sample was taken for analysis of fatty acid composition of milk fat (Aston 1977). Results were analysed by analysis of variance. RESULTS Metabolisable energy content of sorghum meal and the hominy based pellets were similar (Table 2). The hominy pellets had slightly higher crude protein, fibre and fat content. Dry matter and protein of the hominy pellets were more rapidly digested than for sorghum meal (Table 2). Milk yields were increased by 1.4 L/day for cows fed hominy pellets. Yields of protein and lactose were also increased, while fat yield was similar for both groups (Table 3). Fat percentage was lower and lactose percentage Table 2. Chemical analyses and in sacco degradability of supplements Table 3. Supplement effects on milk yield, composition and liveweight Means in rows with different letters are significantly different (P < 0.05) 104 Proc. Aust. Sot. Anim. Prod. Vol. 19 was higher (P < 0.10) for cows given the pellets (Table 3). Molar proportions of C18: 1 and C18:2 fatty acids increased for cows fed hominy pellets, while C4 to Cl6 and Cl80 fatty acids were similar for both treatments (Table 3). Liveweight change was similar for both treatments (Table 3). DISCUSSION Hominy pellets increased milk, protein and lactose yields and maintained fat production, though the 2 supplements had a similar estimated ME content. There are a number of possible reasons for the increased yields in our experiment. Pelleting of feed can improve starch utilisation (T. M. Davison and W. K. Ehrlich, unpublished data). The more rapid degradability of hominy in this experiment is supported by Paliwal et al. (198 1) and could also account for the additional response to hominy pellets. These factors may influence the rate at which energy is made available to the cow. Low dietary protein intake may limit milk production when cows grazing tropical pastures are supplemented with cereal grain and ammonia levels may be insufficient for optimum rumen fermentation (Moss et al. 1991). The same type of pasture was used in our experiment and protein levels in the pasture consumed would be in the order of 13% in the dry matter. We calculated that the sorghum meal diet provided 6 g rumen degraded protein (RDP)/MJ ME while the hominy diet contained 9 g RDP/MJ ME (Mehrez and Qrskov 1977). RDP provided by the sorghum meal may have been less than optimal (ARC 1980), whereas hominy pellets had an adequate level. The higher protein content and more rapid fermentation of protein from hominy may have increased pasture intake and animal production. The decline in fat percentage may have been due to more rapid digestion of the hominy pellets associated with its higher solubility in the rumen. This would reduce the acetic to propionic acid ratio, thus reducing the precursors for fat synthesis, though in our experience we measured only a small decrease in C&Cl6 fatty acids in milk fat (Stobbs and Brett 1972). We conclude that these hominy pellets can be an effective replacement for sorghum grain. The pellet is highly palatable and milk production was increased in this situtation. Feeding hominy pellets resulted in improved profit margins for milk production when cows were fed tropical grass pasture in autumn. Currently hominy pellets are similar in cost to sorghum meal Use of this product would depend on its cost and availability compared with grain. ACKNOWLEDGMENTS We thank Mr I. Buchanan and Mr W. Orr for technical support and Mutdapilly staff for care of the animals. Mr A. Reid carried out the analyses of the milk fatty acids. Q.C.M.A. Rural provided the hominy pellets and support for this experiment. REFERENCES ARC (1980). ` The Nutritional Requirements of Ruminant Livestock' (Commonwealth Agric. Bureaux: Famham . Royal, U.K.) ASTON, J. W. (1977). J. Chromatog. 131: 121. COWM, R. T., DAVISON, T. M., and O' GRADY. I? (1977). Aust. J. Exp. Agric. Anim. Hub. 17: 373-9. MEHREZ, A. Z. and ORSKOV, E. R. (1977). J. Agric. Sci. Camb. 88: 645. MOSS, R. J., EHRLICH, W. and MCLACHLAN, B. (199 1). Proc. 3rd Int. Symp. Nutr. Herbivores, Penang, Malaysia p 60. ODDY, V. H., ROBARDS, G. E. and LOW, S. G. (1983). Proc. 2nd Int. Conference of Int. Network of feeds Information Centres. PALIWAL, V. K., KHIRWAR, YADAV, K. R. and KRISHNA G. (1981). J. Agric. Res. (Haryana Univ.) ll(3): 463. STOBBS, T. H., and BRETT' D. J. (1972). Proc. Aust. Sot. Anim. Prod. 9: 297. , 105