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Incorporating Cull Pumpkins into Livestock Diets

Volume 5 Issue 2

Susan Kerr, WSU

Pumpkins–those beautiful orange orbs of autumn–aren’t just beautiful and delicious, they can also make a pretty darn good alternative livestock feed. Maybe…

Thanks to a large biodegradable mulch trial at the WSU-Mount Vernon Research and Extension Center in 2015 that featured pumpkins, we had a large amount of pumpkins to find a purpose for at the conclusion of the trial. Word went out to area livestock producers to engage in a non-scientific pumpkin feeding trial.

Questions to Answer

Study goals included answering the following questions:

  • What is the nutritional value of pumpkins as a livestock feed?
  • Which livestock species are best suited to eating pumpkins?
  • How much labor is needed to make pumpkins suitable for each species?
  • How much of a normal feed ration could be replaced by pumpkins?
  • Are there any positive or negative effects on animal health or performance?
  • What pumpkin storage issues are involved with long-term feeding?

Photo 1. Straw and pumpkin silage, ensiled 100 days.

Storage Solution = “Pumpkage”?

If temperature and humidity can be controlled, pumpkins can be easily stored for several months, but not forever; mold and rot eventually occur. This is unfortunate because often when cull pumpkins are available, this means LOTS of pumpkins requiring LOTS of storage space, but rarely optimal storage conditions.

Consequently, we wanted to investigate a long-term storage method: “pumpkage” (pumpkin silage). We made two types of pumpkage, ones with and without straw. Through this mini-study, we wanted to learn if and how pumpkins could help upgrade the nutritional value of a low-value fiber source (straw) while expanding the volume of pumpkage without excessive dilution of nutritional value.

For the pumpkage demonstration, whole pumpkins were chopped via a wood chipper and all components (rinds, seeds, guts, stems) were put into a heavy plastic garbage bag in a plastic 5-gallon bucket, manually packed down with a weight to exclude as much air as possible, and tied closed. A lid was placed on the plastic bucket, which remained outside exposed to ambient temperatures. For the version with straw, about one lb. of straw was chopped with the whole pumpkins and the same ensiling process was used as for whole pumpkins. Neither type of pumpkage was inoculated.

After 100 days in storage, samples were removed for analysis; results are included in Table 1. Observations at sampling time included differences in smell and apparent moisture content; both had some glossy white mold on top. Photo 1 depicts the pumpkin/straw silage.

Chemical Analysis and Interpretation

Table 1 contains the chemical analysis of raw and ensiled pumpkins, straw, and straw/pumpkin silage. The protein content in whole pumpkins was surprisingly high, adequate for maintaining adult ruminants but below maintenance requirements for all life stages of pigs. Pumpkage, however, had over 18% protein, which is adequate for growers, finishers, and most mature swine life phases.

The Total Digestible Nutrient (TDN) content was a respectable >72%, meaning it is a good source of energy. Although pigs are not ruminants, the fiber in pumpkins is highly digestible so pigs are able to take advantage of much of the carbohydrate energy contained in the fiber via their hindgut fermentation processes.

The relatively high phosphorus content of pumpkins means care will need to be taken to create an appropriate mineral mix to ensure good health when pumpkins are fed, especially to castrated sheep, goats, and cattle.

Table 1. Nutritional content of pumpkins, pumpkin silage, pumpkin/straw silage, and straw from this study.
**RFV = Relative feed value, which helps compare the energy value of different forages. It reflects digestibility and potential intake. The standard of 100 is mature alfalfa in full bloom.
^ADF = Acid Detergent Fiber which includes a forage’s cellulose and lignin content; a digestibility predictor.
^^NDF = Neutral Detergent Fiber which includes a forage’s cellulose, hemicellulose, and lignin content; an intake predictor.

Feeding Results

Adult pigs required no added processing of pumpkins (smashing, etc.) to promote consumption (Photo 2). They had no aversion to eating spoiled/rotting pumpkins, but due to possible health implications, this practice cannot be condoned. Poultry also readily took to pumpkins, although most needed some help getting the rind cracked. Unlike cull potatoes, pumpkins do not need to be cooked before feeding large quantities to monogastrics.

Photo 2. Pigs offered pumpkins and squash going whole hog with consumption. No additional processing was required for acceptance (photo courtesy Allen Miller).
Consumption via other species (goats, sheep, and cattle) was variable from farm to farm: on some farms, a species might take to pumpkins readily and need no assistance with them and on others, animals were disinterested and/or required significant additional labor inputs, such as cutting pumpkins into pieces. One producer definitely felt the work involved was not worth any cost savings; others were very happy with the results and intend to incorporate pumpkins into future rations if they can find a reliable source.

Observations on a carcass from a cull sow fed pumpkins for an extended time included the meat was very tender, with normal color and good flavor.

Many participating producers fed pumpkins to multiple species, including poultry. In fact, poultry and swine were the most universally successful species in this trial, with all owners reporting immediate, widespread, and thorough consumption.

Limitations

This was far from a controlled experiment with well described treatments and replications. Although pumpkage may have some practical applications when large numbers of cull pumpkins and squash are available and long-term storage is needed and available, the pumpkage from this study was not tested for the presence of harmful bacteria so we did not test its palatability and acceptance by livestock. Also, no amino acid profiling was conducted; this information would be necessary before determining the suitability of pumpkins or pumpkage to pigs or poultry. Caution should be used if and when incorporating large numbers of pumpkins into a livestock ration—as always, changes should be made gradually to prevent serious gastrointestinal repercussions.

Recommendations

Cull pumpkins and squash may indeed be viable and valuable alternative feeds for PNW livestock if they can be acquired for little or no cost and reasonable transportation and labor costs. Based on the preliminary results of this pilot study, whole pumpkins seem best suited to adult pigs when added to their normal balanced ration at a rate of up to 10% of the dry matter fed. Due to the relatively high phosphorus content of pumpkins, the entire ration’s mineral status would have to be analyzed and balanced for optimal animal health, performance, and growth. Pumpkins could also have a place as part of poultry diet as well, with the preceding mineral caveats.

It is NOT a recommendation of this study for livestock owners to plant pumpkins as a livestock feed. Pumpkins are not the most efficient use of tillable acreage because they require a lot of space and other crops could produce more energy/tonnage/protein per acre. Cull or surplus pumpkins are something to consider, however, if they are available at a reasonable cost from a wholesaler.

Not all guiding questions were answered with this pilot study. Future efforts will include determining amino acid content of whole pumpkins and pumpkage, safety of feeding pumpkage, and palatability/acceptance of pumpkin silage by livestock.