It is important to have high quality corn silage as it helps to supply energy and fiber for the dairy cows, reducing the purchasing feed costs from grain and other byproduct supplements, increasing the farm's profitability.
Here are some strategies that may influence the nutritive value of corn silage through increases in starch as well as neutral detergent fiber digestibility (NDFd).
Maturity At Harvest
Let the corn plants stand longer in field with the purpose of obtaining grater yield of starch has been a common practice.
In recent studies, reduced starch digestibility was observed in diets that contain corn silage harvested with more than 40% dry matter (DM).
This may be due to an increase in the proportion of vitreous endosperm in the kernel associated with greater maturity.
In addition, as corn plat matures, the lignin content also increases.
Other challenges related to the harvesting of drier corn silage (more than 40% DM), such as packing issues and poor aerobic stability must be considered when targeting mature corn silage.
Studies have also shown that yeasts obtained from spoiled silage reduced the capacity of the rumen microbes for digesting NDF.
Hence, greater maturity beyond 40% DM at harvest may limit not only starch but also NDFd of corn silage.
Therefore, proper maturity at harvest is crucial to maximise the nutritive value of corn silage.
Research has shown that there is a greater starch digestibility when corn silage was processed using 1 - 3 mm roll gap settings as compared to 4 - 8 mm processed and unprocessed corn silage.
This is due to increased in surface area for bacteria and enzymatic digestion of finer particles.
There has been a new method of harvesting corn silage, shredlage, which targets harvesting of corn silage at a longer theoretical length of cut (TLOC) while still maintaining or oimproving the degree of kernel processing.
From studies, it is shown that using corn shredlage has greater kernel processing and thus, starch digestibility as compared to conventional-processed corn silage.
Feeding corn shredlage also enhanced the cow's lactation performance.
With that being said, using corn shredlage did not increase milkfat content and rumination activity.
One of the ways to increase nutritive value of corn silage is by varying the cutting height.
Studies have shown that increasing the cutting height, thus more lignin and NDF was left in the field, increasing NDFd and starch content, causing higher milk production.
However, increased cutting height reduced DM yield per acre, reducing milk per acre.
Therefore, farmers should prioritise for maximum yield versus higher quality and determine if this harvest practice is feasible.
Studies have shown that extended time in storage increases ammonia-N, soluble CP and starch digestibility in corn silage.
Hence, it is recommended to feed harvested crop only after 4 months or more in storage.
There is also no sign of negative effects of vitreousness and maturity at harvest on starch digestibility due to extended storage.
With that being said, proper silo management is required during filing, packing and covering to ensure the benefits of fermentation patterns.
Hybrid selection is a good way to increase NDFd in corn silage.
Take BMR hybrids for example, they consistently show greater NDFd as compared to other hybrids.
With that being said, feed efficiency was similar among hybrids and starch digestibility was lower for BMR hybrids.
In summary, many factors such as hybrid selection, proper maturity at harvest, kernel processing and extended storage length affects the maximum starch digestibility in corn silage.
Hybrid selection, proper maturity at harvest and increased cutting height also helps to increase NDFd in corn silage.
Before selecting a new hybrid for your herd, it is important to evaluate the results from hybrid performance trials around your farm for a period of time.
Lastly, extended storage length and increased cutting heights will require proper inventory planning.