Final Report to Midwest Forage Association. Krishona Martinson and Craig Sheaffer University of Minnesota

Transcription

1 Final Report to Midwest Forage Association THE EFFECT OF HARVEST MOISTURE, BALE WRAPPING, AND THE APPLICATION OF AN ORGANIC ACID BLEND ON FORAGE QUALITY AND TEMPERATURE IN GRASS HAY Krishona Martinson and Craig Sheaffer University of Minnesota INTRODUCTION Since 2000, there have been over 900 livestock and poultry barn fires in Minnesota, resulting in over 26 million dollars in damages (Minnesota Fire Incident Reporting System - MFIRS). Although not specifically tracked by MFIRS, a number of these fires have been caused by spontaneous combustion of hay that was baled too wet. level at time of baling is a significant factor leading to hay heating and fire (1,2,3). The relationship between forage moisture and the resulting bale temperature has been studied in small and large square bale dairy quality hay, but not in horse quality grass hay. Most guidelines currently used in the equine community are extracted from dairy related research results. However, horses are highly sensitive to mold (4). Guidelines for hay moisture at time of baling established for cattle may be too high for mold sensitive horses. Ingesting moldy hay can result in both short-term and long-term respiratory problems in horses, specifically heaves and colic (4). Moldy hay also can cause human respiratory distress in addition to labor and financial burdens related to replacing and disposing of the moldy hay. Previous research suggests that large hay packages need to be dried to less than 17% moisture if intended for use as quality horse hay. In Sweden, researchers have investigated plastic wrapping round bales at about 35% moisture (5). Wrapping bales at this moisture level results in minimal fermentation and has been shown to be safe for horse feed. Even though bale wrapping is an accepted means of forage processing for cattle, it has not been accepted or researched extensively in the horse community in the United States. Bale wrapping may be a strategy to provide high quality horse hay. While many horse owners select hay based on different characteristics (color, smell, type of hay or hay mix), one characteristic remains the same: is it must be dust and mold free. While the window for baling premium, rain free hay is narrow, mostly due to environmental challenges, the use of preservatives during the baling process has been shown to effectively preserve high moisture, aerobically stored hay (6,7). Preservatives at rates of 1-2% are used to prevent mold formation and the most common hay preservative is an organic acid preparation containing buffered propionic acid. In a free-choice palatability trial, horses preferred alfalfa that was not treated with a preservative over alfalfa that had been treated with a mixture of acetic and propionic acid (8). However, another study found that yearlings receiving hay treated with preservative consumed and gained as much over a 1-month feeding period as yearlings consuming untreated hay (9). Clinical measures of well-being such as serum enzyme levels were 1

2 not affected by consumption of preservative-treated hay, indicating the hay had no negative effects on the horses. The objectives of this research were to: 1. Determine the relationship between moisture at time of baling on hay, forage quality, and mold formation in large round baled grass hay. 2. Determine the effect of wrapping and hay preservatives on the forage quality of large round hay baled at different moisture ranges. MATERIALS AND METHODS Thirty six 4 x 5 round bales (~1,000 lb) were baled and net wrapped at three different moisture ranges: less than 15, 20 to 25, and 30 to 35% (wet basis). at time of baling was estimated with a forage moisture probe. Table 1 outlines the specific treatments. Each treatment was replicated four times in a randomized complete block design. First cutting, flowering grass (primarily orchardgrass) hay was baled in After baling, each bale was cored (0.8 diameter by 20 long), and the samples were analyzed for a basic equine forage nutrient composition and fiber by a commercial forage testing lab. Table 1. Treatments TREATMENT BALE MOISTURE RANGE (%) WRAPPED ORGANIC ACID 1 Less than 15 No No 2 Less than 15 Yes No No No No Yes Yes No Yes Yes No No Yes No No Yes A commercially available organic acid blend hay preservative (Fresh CUT Plus brand Kemin Industries, Inc.) was applied to higher moisture bales during baling at 10 pounds/ton (1.0%). After baling and sampling, three temperature sensors were placed in each bale at approximately 15, 30 and 45 from the top of the bale, and approximately 24 into the bale. Bales were sampled, temperature sensors were placed, and the bales were then immediately wrapped. Commercial bale wrapping equipment was used and bales were wrapped six times with one mil plastic wrap for an average covering of 6 mils. The temperature sensors recorded temperature every hour for 10 weeks. After 10 weeks, the sensors were removed and 2

3 additional cores were taken on each bale to determine forage quality and mold counts and identification. The bales were stored outside (to simulate a common storage method) on a well-drained surface in a row running east and west with three bales of each moisture treatment type tightly butted against each other. A round bale border was placed on both ends of the row and in between each group of bales. The fourth bale of each moisture type was set apart from the row, and served as a non-treated control. Data was analyzed using Proc Mix in SAS and mold counts were log transformed. RESULTS AND DISCUSSION MOISTURE AND FORAGE QUALITY Tables 2-4 outlines the target moisture, actual moisture, and hay quality characteristics of baled hay subject to wrapping and preservative treatment. The actual moisture content of baled forage was sometimes less than the 20-25% and 30-35% target moistures. Protein, fiber, ADF, NDF, and DE were similar at baling for the three target moistures. For forage baled at 15% moisture, wrapping the bales did not affect moisture or forage quality of these bales between June and September. There were treatment effects (P< 0.05) on forage quality for hay baled at 20-25% moisture. Both moisture and protein decreased from baling in June to sampling in September. Wrapping resulted in an increased equine digestible energy (DE) compared to bales that were not wrapped in some treatments The application of an organic acid blend did not result in the maintenance of forage quality throughout the experiment at the higher moisture levels (20-25 and 30-35%). MOLD POPULATIONS Tables 5 and 6 shows mold population of hay baled at the three different moisture ranges with and without wrapping and the application of an organic acid blend. at time of baling had a significant (P<0.05) effect on mold counts, with hay having less than 15% moisture resulting lower mold counts. Wrapping significantly lowered mold counts in all moisture ranges. The moisture by wrapping interaction was also significant (P=0.00). The application of an organic acid blend did not resulted in reduced mold counts. Because mold is naturally occurring in the environment, hay containing less than 500,000 cfu/g of mold is considered safe and poses little risk to horses when fed (10). Hay baled at less than 15% moisture and bales that were wrapped fall into this category (with the possible exception of the 30-35% wrapped bales). Hay containing over 1,000,000 cfu/g of mold should not be fed to horses (based on the recommendation to cautiously feed to bovines at the same level) and constitute treatments that were not wrapped in this experiment. Although not tested in this experiment, hay containing Aspergillus species can produce the mycotoxin aflatoxin and Fusarium species can produce vomitoxin. Aflatoxins and fumonisins 3

4 are important mycotoxins with respect to equine performance, health, metabolism, and reproduction (4). Aspergillus and/or Fusarium were present in all treatments. However, the mere presence of these organisms does not guarantee the production of mycotoxins. Aflatoxins have been shown to have severe adverse effects on horses. Clinical signs include weight loss, anorexia, poor body condition, increased body temperature and heart rate, lethargy, depression, lameness, and bilateral congestion of the eyes. Horses are susceptible to the feeding of grains contaminated with Fusarium mycotoxins. Dietary concentrations as low as 10 mg/kg of Fusarium are associated with fatal equine leukoencephalomalacia (ELEM) which is a multifocal neurological disease of horses characterized by signs of depression, abnormal behavior, head pressing, ataxia, agitation, dementia, and blindness. Muco, Alternaria, and Scopulariopsis species are considered common molds and are not likely to produce mycotoxins. CONCLUSION Hay baled at less than 15% moisture had stable forage quality over the 10 week period and resulted in low mold counts that are considered safe for livestock feed. Wrapping hay at less than 15% moisture did not improve forage quality or mold counts. Thus, it appears that wrapping dry hay does not maintain the quality of hay (compared to not wrapping) stored outside and is an unjustifiable additional expense. Wrapping hay maintained forage quality and reduced mold counts in the higher moisture ranges (20-25 and 30-35%) and resulted in forage suitable for livestock feeding. Treating bales with an organic acid blend at the application rate chosen did not result in maintained or improved forage quality or reduced mold counts. However, there is a trend towards lower mold counts in treated bales, and the treatment with the lowest amount of mold included both wrapping and the addition of the organic acid blend at the 20 to 25% moisture range. It is probable that the application rate of the organic acid blend should be increased in order to achieve desired results. ACKNOWLEDGEMETNS This research was sponsored by a grant from Midwest Forage Association and additional support from Kemin Industries, Inc. The authors would also like to acknowledge the cooperation of Leaning Pine Farm and McNamara Farm Services. 4

5 Table 2. Target and Actual, and Hay Quality of Orchardgrass Hay Baled at Three levels and Wrapped Target Wrapped 15 No 15 Yes 20 No 20 Yes 30 No 30 Yes Date Actual CP* ADF* NDF* DE* CA* P* LSD (0.05) NS *CP (Crude Protein); ADF (Acid Detergent Fiber); NDF (Neutral Detergent Fiber); and DE (Equine Digestible Energy) 5

6 Table 3. Target and Actual, and Hay Quality of Orchardgrass Hay Baled at Two levels and Treated with an Organic Acid Blend Hay Preservative Target 20 No 20 Yes Preservative Date Actual CP* ADF* NDF* DE* CA* P* No 30 Yes LSD (0.05) NS NS NS *CP (Crude Protein); ADF (Acid Detergent Fiber); NDF (Neutral Detergent Fiber); and DE (Equine Digestible Energy) Table 4. Target and Actual, and Hay Quality of Orchardgrass Hay Baled at 20 25% and Treated with an Organic Acid Blend Hay Preservative and/or Wrapped Target Actual Wrapped Preservative Date CP ADF NDF DE CA P No No No Yes Yes No Yes Yes LSD (0.05) 4 2 NS NS NS *CP (Crude Protein); ADF (Acid Detergent Fiber); NDF (Neutral Detergent Fiber); and DE (Equine Digestible Energy) 6

7 Table 5. Mold Population of Hay Baled at Three Different Ranges With and Without Wrapping and the Application of an Organic Acid Blend Treatment Wrap Mold Count (cfu/g) Mold Species* 15 N 3,640 B Fusarium Mucor Alternaria 15 Y 4,900 B Mucor Aspergillus 20 N 4,091,664 A Aspergillus Alternaria 20 Y 1,645 B Mucor Aspergillus Fusarium Scopulariopsis 30 N 3,423,734 A Aspergillus 30 Y 5,692 B Aspergillus Scopulariopsis Fusarium * Only major mold species reported. Different letters in the mold count column represent significantly different values Table 6. Mold Population of Hay Baled at 20-25% With and Without Wrapping and the Application of an Organic Acid Blend Treatment Wrapping Preservative Mold Counts (cfu/g) Mold Species* No No 6,671,139 A Aspergillus No Yes 2,510,152 A Aspergillus Alternaria 20 Yes No 1,992 B Fusarium Mucor Yes Yes 1,358 B Aspergillus Scopulariopsis * Only major mold species reported. Different letters in the mold count column represent significantly different values 7

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