Silage Research

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High Quality Silage can be Used to Replace a Substantial Proportion of the Grain in Finishing Diets for Cattle


Field trials in NSW in 1991-92 on commercial properties showed that high quality silage can be successfully used in finishing diets for cattle in a range of environments. High silage diets will support satisfactory animal performance, produce high quality carcass and meat suitable for the domestic market, and significantly improve net returns per head.

By using silages capable of supporting > 0.8 kg/day when fed alone, it was considered possible to reduce the proportion of grain in the diet from 80% to as low as 30%.
Dr. Alan Kaiser. "Alternative Finishing Strategies for the Production of High Quality Beef". MRC Report for DAN.040. Sept 1993.
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Switching to Silage from Pasture can Significantly Increase the Stocking Rates of Animals per Acre for Dairy Farms


At the Silage Discussion Day on 17/7/97 organised by the Australian Tropical Dairy Institute, farmers reported that switching to silage had enabled them to double the size of their herd without increasing the size of their properties.

The theoretical basis for this improvement is considered to be that:

1. the silaging of pasture leads to an increased % utilisation of available pasture and better re-growth of pasture after cutting for silage;
2. the silaging of maize leads to higher milk production, higher volume of feed per acre and a higher net profit.
Australian Tropical Dairy Institute, July 97, Silage Discussion Day, with Dr. Keith Bolsen and Dr. Tom Cowan.Dr. Alan Kaiser. " The Role for Silage in More Intensive Grazing Systems". Proc. 9th Conf. Grassland Soc. NSW 1994, pp 40-47.
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Good Silage Making Techniques are Much More Profitable than Poor Silage Making Techniques


1. Crop stage:
Maize should be 30 - 36% DM when the kernel is in the 60-80% milk-line.
Wet Grasses & Legumes should be field-wilted to at least 25% DM.

2. Chop Length:
1 cm for maize & sorghum.
1-2 cm for field-wilted grasses & legumes.

3. Packing Pits:
Pits should be rolled with a single-tyred tractor driven slowly, without spinning the tyres.
Dr. Keith Bolsen. 1997. "Questions and answers about Silage towards 2000." July 97, Silage Discussion Day. Queensland.
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More Recent Techniques for More Profitable Use of Silage


1. Heating on feed-out can be a big problem, especially with maize silage. Minimising heating requires a pit design with a narrow cutting face, a smooth cutting surface, a removal rate of 10 - 20 cm from the face per day, efficient feed-out methods and daily feed-out.

2. Top spoilage of pits can be eliminated completely by good rolling and covering. For pits covered in plastic and tyres, the tyres should be touching each other.

3. Silage pits should be filled from back to front, not in layers, and built small enough to be filled in 3-5 days. Most pits are too big to allow top quality.
Dr. Keith Bolsen. 1997. "Questions and answers about Silage towards 2000." July 97, Silage Discussion Day. Queensland.
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Bacterial Inoculants should be Applied to Every Load of Forage Ensiled


Using good techniques, maize silage in particular can be made to look & smell perfect without inoculant. ... BUT ....

1. 28 farm scale trials, which evaluated 71 silages, showed that bacterial inoculants consistently improved:
- fermentation efficiency
- DM recovery (of silage from the pit)
- feed to gain ratio
- liveweight gain per ton of crop ensiled
for both maize and forage sorghum silages.

In contrast, applying urea or anhydrous ammonia adversely affected these parameters.

2. In these trials, an investment in a bacterial inoculant costing US$1/tonne ensiled yielded a net profit
(a). based on weight gain, of US$2-$4/tonne of maize ensiled and
(b). based on increased milk, of US$4-$8/tonne of maize ensiled.

"I could not recommend one more tax dollar being spent in Australia to repeat the research on bacterial inoculants." Dr. Keith Bolsen. 1997 ... in response to the question of whether there is sufficient research proof that bacterial silage inoculants would increase profits for Australian farmers.
Bolsen, KK. et al. 1992. "Evaluation of inoculant and NPN silage additives: a summary of 26 trials and 65 farm-scale silages." Kansas Agric. Exp. Sta. Rpt. of Prog. 651: 101-102.Keith K. Bolsen. 1997. "Improving Silage Preservation Efficiency and Quality." July 97, Silage Discussion Day. Queensland.

1. Research results from
- over 200 laboratory-scale studies
- 1,500 silages
- 25,000 silos
indicated that bacterial inoculants were beneficial in over 90% of the comparisons.

2. Inoculated silages had
- faster and more efficient fermentations
- lower pH, esp. in the first 2-4 days
- higher lactic content
- higher lactic to acetic ratio
- lower ethanol and ammonia values.

This is why inoculated silage pits gave more tonnes of silage out than the control pits, even though the control pits looked perfect. It is also why each tonne from inoculated silage pits gave better animal performance than a tonne from control pits.

3. These results explain why the 28 farm-scale trials involving 71 silages showed the clear net profit achieved by investing in bacterial inoculants.

4. "Bacteria do not have passports ... they are not different here in Australia. The climate and conditions in Kansas are not that different to here in Australia. Australian silage makers should be using bacterial inoculants for all crops ensiled." Dr. Keith Bolsen. 1997
Dr. Keith K. Bolsen. 1997. Invited Speaker July 97, Silage Discussion Day. Queensland.Bolsen, KK. Et al. 1992. "Evaluation of inoculant and NPN silage additives: a summary of 26 trials and 65 farm-scale silages." Kansas Agric. Exp. Sta. Rpt. Of Prog. 651: 101-102.Keith K. Bolsen. 1997. "Improving Silage Preservation Efficiency and Quality." July 97, Silage Discussion Day. Queensland.
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Components of a Good Inoculant


1. A Bacterial Inoculant should provide 100,000 cells per gram of forage and be based on the species, Lactobacillus plantarum. Other bacteria, which grow at a higher pH than Lactobacillus, are important in the initial fermentation phase. Dr. Keith Bolsen. 1997.

2. Other additions to bacterial inoculants have been found to be of doubtful value, including:
(a) propionibacteria
(b) enzymes (Limin Kung 1997)

3. Freshly cultured inoculants have been shown to produce a much stronger fermentation than powdered inoculants. (Merry et al. 1995)
Dr. Keith Bolsen. 1997. "Questions and answers about Silage towards 2000." July 97, Silage Discussion Day. Queensland.Dr. Limin Kung. Univ. of Delaware. 1997 Web Page.Merry et al. 1995. " Use of freshly cultured lactic acid bacteria as silage inoculants. " Grass & Forage Science 50: 112-123
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How a Bacterial Inoculant works in a Silage Pit


Silage Inoculant improves all Silage

Farm scale tests have now shown that bacterial silage inoculants improve the net profit from using silage, even when untreated silage looks perfect (see previous results of Keith Bolsen). How does this work ? All silage suffers some loss of protein (and, therefore feed value) during the time taken to complete silaging. The longer silaging takes, the more the protein spoilage. Silage inoculants reduce spoilage by reducing the time to complete silaging (see refs #1 & 2).

Microbial Attack & Defence during Silage Making

Silage making is a process using microbial defences against attacks by other microbes. The silaging process has 3 phases.

In phase 1, the attacks come from spoilage Enterobacteria (see ref #1) and by the proteases released by the herbage on harvesting. The defence against phase 1 attacks is the elimination of air and the initial reduction of the pH to about pH 5.0 which is done by microbes such as Enterococcus faecium (silage inoculant A in the diagram below). Silage inoculants generally speed up acid production and prevent ammonia formation (see ref #3), minimising protein losses.

In phase 2, it is essential for the pH to be reduced to the lowest value (generally about pH 3.5) as soon as possible. This is achieved by Lactobacillus plantarum. Failure to achieve phase 2 allows the growth of Clostridium, which attacks the silage in 2 waves. The first wave of Clostridium raises the pH and produces butyric acid, which reduces palatability. The second wave of Clostridium produces ammonia and proteases, which cause extensive destruction of silage. Although extensive phase 2 microbial attacks are not common, a strong level of Lactobacillus plantarum (silage inoculant B in the diagram below) in a silage inoculant is essential.

Difficulties using Silage Inoculants in Australia

Inoculants are biological products which can be destroyed by improper handling and many people have considered that inoculants are ineffective because of their experience with products which may simply have died during importation. To survive, inoculants generally need to be properly vacuum packed (see ref #4). Australian scientists have recently developed a silage inoculant which grows for up to 5 days in the tank after the solution has been made up for spraying (see ref #5). This unusual capability allows several days of usage of the solution and delivers freshly growing cultures, which are more active than normal inoculant powders.

1. Selmer-Olsen et al. 1993. Grass & Forage Science 48: 45-54.
2. Cussen et al. 1995. Grass & Forage Science 50: 249-258.
3. Keady & Steen. 1994. Grass & Forage Science 49: 438-446.
4. Stanier et al. 1966. General Microbiology. 2nd Edition, p315.
5. Genesearch Research Report. 1996.

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