Richard Ehrhardt, Michigan State University Extension Specialist, Small Ruminants
(Previously published on MSU Extension, Sheep & Goat: May 10, 2015)
A closer look at adding silage to your sheep feeding program.
Have you ever considered making and feeding silage? This is a common question Michigan State University Extension ask producers when reviewing their forage plans, so let’s take a closer look at silage feeding systems to help you consider if it could be a good fit for your farm. I have been feeding silage for about 15 years, and it is clear to me that my particular program would not work without silage as a centerpiece of my feeding program.
Note in the picture how the plastic is left on the bottom of the bale to retard spoilage in this simple feeding system. This high-quality forage was made from a predominantly grass pasture, harvested at the right time and carefully processed to insure quality. Baled silage is the dominant feed in the farm’s lamb finishing program.
Silage as a means of forage preservation offers control over the single most important factor that determines forage quality: date of cutting. Dry weather days are always at a premium in Michigan during the months of May and into mid-June, when optimal harvest windows occur for perennial forages (grasses, legumes, and their mixes). Occasionally, there are a string of warm, dry days in late May or early June in the upper Midwest, but they are rare and certainly cannot be counted on. Therefore, dry hay programs are forced to cut forage when it is far too mature, waiting until dry weather becomes more predictable in late June. Forage quality declines rapidly when cutting is delayed, as the plants become far less digestible to livestock, filling with lignin which cannot be digested in the rumen. This happens more quickly in grass than in alfalfa and other legumes, creating the common misperception that grass is always poorer quality than alfalfa forage. It is true that grass does not maintain its quality as long as alfalfa does as it matures, but what if you could harvest grass earlier, before its quality declines? The simple answer is that you would have awesome forage with high digestibility and, therefore, quality! It is entirely possible to put up grass forage that rivals and even exceeds alfalfa in terms of energy (75 percent total digestible nutrients, TDN) if harvested before becoming overly mature (less than 50 percent neutral detergent fiber, NDF). In most sheep production feeding scenarios, energy is far more limiting than protein, so forage systems that preserve energy concentration should be a point of focus. The key to this is timely harvest, and simply put: silage allows timely harvest! By only having to wait one or fewer days for the entire forage harvest process, more harvest windows are created. Additionally, timely harvest early in the season also sets the stage for quality harvest for the rest of the season, in that degree-days and moisture are captured as highly digestible vegetative growth, instead of lignified, poorly-digested material that has little value.
This leads me to a perception problem I hear in the field expressed as, “This forage is good enough for sheep – sheep don’t need good forage.” I not only find this a troubling statement and a cop-out for producing good forage, but just nonsensical. While it is true that any cow, sheep, or goat can generally survive on poor forage; sheep, just like dairy cows, will do much better on quality forage. Forage-wise, sheep will waste far less if the quality is high and will require far less grain or even no grain in some circumstances when fed quality forages. Animal performance will increase, higher lambing rate, higher conception rate, better milking ewes, and incidence of feed-related problems will go down (acidosis, enterotoxemia, pregnancy toxemia). Reducing reliance on expensive energy and protein supplements is critical for profitability. There are even producers who are using high quality silage as a major component of lamb finishing programs. In these cases, the cost per pound of gain is not necessarily vastly improved over grain diets. But it does increase feeding options for the farmer and may be a good fit for some grain-limited or grain-averse producers. In the end, if producing quality forage is simply a management issue, why not solve this problem and take better care of your sheep? They will pay you back in return.
Silage also offers huge advantages over dry hay due to much lower harvest and storage loss. Harvest loss includes losses in total yield as well as quality. Ever notice how an alfalfa crops loses leaves quickly and extensively as the forage dries and is worked by hay-making equipment? Alfalfa leaves contain much of the quality found in alfalfa, since the stems are high in poorly digested fiber. Leaf loss is minimized when the hay is handled when wilted and less dry, as occurs during silage making. With dry hay production, total harvest loss may exceed 30 percent, and the quality will always be lower than silage harvested at a similar time. Table 1 shows a simple example of this in a field of alfalfa/grass mix forage harvested past the optimal quality harvest date in early June.
Table 1. Alfalfa/grass field cut on June 11, 2011 in Ingham county, MI and harvested either as baled silage or dry hay.
|Baled silage||Dry Hay|
|Percent Crude protein||14.1||11.5|
|Percent Acid detergent fiber (ADF)||34||40|
|Percent Neutral detergent fiber (NDF)||56||63|
|Percent Total digestible nutrients (TDN)||65||56|
|NDF digestibility (48h, percent of NDF)||62||51|
|Relative feed value (RFV)||148||93|
|Estimated harvest loss (percent of dry matter)||23|
Optimal harvest for a mixed alfalfa/grass crop would be around 45 percent NDF (40 percent for pure alfalfa and 50 percent for pure grass stands), so this particular field was harvested about 20 days past its prime for quality. In this case, the field was cut on a single day, with half of the field harvested as baled silage the following day and the other half as baled dry hay 2 days later. As shown, even when forages are harvested past their prime for quality, there are huge differences in forage quality when cut on the same date and harvested by the same equipment as dry hay versus silage. In addition, we estimated that the dry hay yielded 10 percent less total crop, adding further insult to injury. The final dagger is storage – dry hay requires storage in buildings (costly by themselves or in terms opportunity cost for other use such as feeding lambs, etc.) whereas silage is already covered, eliminating this need and reserving building space for more valuable use.
Finally, silage also offers advantages over dry hay in terms of feeding loss. Again, leaf loss is minimized when feeding silage due to its higher moisture content and the sheep’s tendency to eat more of the stemmy material when ensiled compared to the dry stemmy material found in dry hay. The fermentation process renders the forage soft and tasty instead of dry and sharp – it’s no question why animals prefer silage when given the option of both.