Study Of Use Of Maize For Silage

Press, Volume CIII, Issue 30562, 3 October 1964, Page 9

Study Of Use Of Maize For Silage

[By

D. J. G. DAVIES,

, of the Department of Agriculture, Christchurch.]

Now that a number of farmers are preparing ground for sowing in the new season’s maize crops, it would seem appropriate to review the results of silage investigations and demonstrations carried out during the 1963/6-1 season.

Without a doubt last year’s growing conditions proved to be the most marginal for maize crops that Canterbury farmers have experienced for many years. Notwithstanding the unusually cool temperatures, plus late frosts, a number of farmers were still able to grow maize in sufficient quantity to meet their summer and autumn greenfeed requirements. Best .results were obtained by those who sowed their crops in midNovember and early December. Early sown crops definitely did not pay off. The virtues of maize for maintaining and even increasing summer milk production are well known, but not so well known is the potential value of maize when converted into silage. It is about this latter aspect that this article is mainly concerned.

The main objectives for making good maize silage, apart from adequate facilities, are:—

(1) A variety which will mature to the “early dent” or doughy stage of ear formation sufficiently early to avoid hard frosts and allow establishment of new pasture. (2) A dry matter content of at least 30 per cent or higher. (3) A pH or acidity level of 4.0 or lower. (4) A high ratio of mature ears to leaf and stem. Examination of the following results indicates how near we have approached the ideal in some respects, but still have some way to go in others. For the third consecutive year, but at differing stages of maturity each year, silage was made in the miniature concrete tower silos at the Crop Research Division of the D.S.I.R. at Lincoln. As far as crop development allowed, silage was made at the “early dent” stage with crops of maize originally sown for summer greenfeed. For last season this meant harvesting the variety Wisconsin 575 about mid-April. An innovation was the decision to compare the new technique of vacuum packing with conventional methods ,of silage making. .For the former plastic sleeves were fitted into two of the four silos and the air extracted by vacuum pump.

The following table compares the results obtained between the two systems last year (figures are the means for each pair of silos):

Unfortunately an air leak occurred .in one of the vacuum packed silos and this made the loss figure higher than normally would have been expected. From the above dry matter figures it is obvious there is a need for substantial improvement. This could be achieved by wilting the crop for several hours prior to cropping and transporting it to the silo, and by the use of early maturing varieties to allow harvesting when day temperatures in, say March, are likely to be higher than those experienced in April. Mr T. P. Palmer, a plant breeder at the Crop Research Division, tested a range of varieties last year, several of which showed distinct promise in fulfilling the above requirements. As well as the vacuum pack comparison described above, a field demonstration was carried out on the property of Messrs H. Thomas and Son, Greenpark. A 50-ton bun-type stack was made using a plastic base and cover and the two sheets were kept air tight by a specially designed seal strip which clamped together simply and was easily un fastened.

When opened early last month, the material was found to be in a near perfect state of preservation. The stack was a mixture of finely chopped and coarse flailchopped (W575 maize) as two different machines were used to speed up the demonstration.

Dr. R. M. Allison, of the Crop Research Division, who has arranged for all the chemical analyses of the maize samples, reported that a near perfect fermentation in respect of acidity and freedom from air contamination had been obtained. The pH was 3.7, the dry matter content 21 per cent and the estimated loss less than 10 per cent. Again a rather low dry matter figure was obtained, because there was no wilting before ensiling. The finely chopped material was considered to be more easily handled than the flail-harves-ted maize, although animals eating the silage did not appear to differentiate between them.

As far as the vacuum technique is concerned the points that impressed were: (1) The complete elimination of obnoxious smells. (This silage smelt rather like fermented brewers’ grains). (2) The virtual elimination of waste. (3) A minimum of drainage effluent, seeping from the stack. (4) The over-all efficiency of the method, both at harvesting and feeding out. Having succeeded in making silage that, at least,

chemically met the desirable standards, it was found that two of the three herds had considerable doubts about the palatability of the material offered. This result is thought to be due primarily to the low dry matter levels obtained, combined with the low ratio of mature cobs to leaf and stem. However, when the silage was fed to 19 steers on the property of Mr G. Diedrich, Halswell, their reaction turned out to be the success story of the whole project. Their intake over a period of two weeks was in excess of 601 b per head per day when fed in wooden feed bunks. In addition their daily ration included rolled barley and hay. An important observation made was that the longer the silage was exposed to the air the greater the amount of heating that occurred and the less acceptable the silage became to the animals being fed. This reaction underlines the importance of avoiding exposure of vacuum silage to the air for unduly long periods. Preferably stacks should be recovered between feeding periods, with a minimum of disturbance of the silage mass. Finally the following points should be noted by farmers wishing to convert maize into silage:— (1.) Choose an early maturing variety—the best at present available commercially is W575 (once removed from imported seed) but it is hoped that a superior variety will be available by the 1965 season. (2.) Sow in 12in. to 14in rows at seeding rates between 40 to 451 b per acre. (3.) Use a harvesting machine which chops or lacerates fine rather than coarse, long, stringy material. (4.) Roll or cut crop in morning to promote wilting. Pick up crop with suitable lifting equipment when dry conditions obtain two to three hours later in the day. (5.) The highest yield of digestible .nutrient for silage will be obtained when the ears of corn have reached the early dent or doughy stage of development. With present varieties this means harvesting between midMarch and mid-April, depending on seasonal effects.

(6.) Losses must, be kept to a minimum by achieving maximum exclusion of air. Rolling -with a tractor will assist, or alternatively consider trying the vacuum pack method of air elimination. (7.) Whichever method Is used, the stack must be completely covered with airtight sheeting and weighted down with bags of earth or old tyres. Avoid anything that may puncture the covering material. (8.) Provide good drainage for effluent from stack and water run-off. In conclusion, readers are reminded that maize silage investigations are by no means complete, and that the search for more desirable varieties, as well as improved harvesting and handling techniques, and most important of all, improvement of the value of the product to stock, must be continued.

pH Acidity Dry Matter Calculated Method Density Top Bottom Top Bottom Losses Conventional 20.51b/cu. ft .. 4.4 4.0 16.5 ‘22.4 16.5% Vacuum Pack 35.01b/cu. ft. , 4.2 4.0 20.5 20.0 15.0%