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UDC 636.2.085.523.1
IMPACT OF HAYLAGE HARVEST AND STORAGE TECHNOLOGIES ON FORAGE MICROBIAL CONTAMINATION
Artemyeva O.A., Candidate of Biological Sciences Duborezov V.M., Doctor of Agricultural Sciences Pavlyuchenkova O.V., Kotkovskaya E.N., Candidates of Biological Sciences
Ralkova V.S., Researcher Peresyolkova D.A., Junior Researcher All-Russia Research Institute for Animal Husbandry, Moscow, Russia E-mail: [email protected]
ABSTRACT
To develop bacteriological regulations for harvesting and storing haylage, microbial contamination of feeds has been studied using different technologies for harvesting haylage and laying fodder in trench and concrete ring silos, and rolls. It was noted that the analyzed forage samples had no pathogenic microorganisms and Enterobacteriaceae, including Salmonella. There was a lack of toxicity in all analyzed silage samples. The values for the number of mesophilic aerobic and elective anaerobic bacteria, and concentrations of lactic-acid bacteria, mold and yeast fungi in samples were lower than in the feedstock. Microbial contamination values were better for haylage obtained from the plants cut 25 cm above the ground level (when compared to the plants cut to 9 cm height). Rates of contamination were lower in haylage packed into film bags than into trench silos that might give reason to recommend the given harvesting technique. Permissible contaminant levels without any negative impact on haylage quality have been identified.
KEY WORDS
Haylage; Harvesting technologies; Trench silo; Concrete ring silo; Roll; Forage equipment; Microbiological parameters; Mold; Yeast-like fungi; Mesophilic aerobic and elective anaerobic bacteria.
An increase in efficiency of animal husbandry depends on the feed production growth as well as the rise in the fodder quality, decrease in loss of feed nutrients by the means of harvest and storage technology developments.
Feeds, feed additives and feedstock should not contain microorganisms, their toxins or their metabolites of unacceptable amount, which represents health risks of farm animals [8].
Safe levels of microorganism contamination in bulky feeds harvested using different technologies should be taken in consideration when developing microbiological regulations. It should be reasonable to determine common indices of safety and certain pathogenic microorganism contents to ensure the health of farm animals and subsequently consumers [1, 4, 9].
Research findings depend on an applied analytical method; that is why, an appropriate standard method should be determined for each microbiological item. However, fodder suppliers and forage producers should have the opportunity of applying analytical and particularly expressive methods differed from the standard methods, provided the use of these alternative methods can yield equivalent results. Moreover, it is necessary to determine the rules of sampling and the methods of analyzing for each item to perform the study more precisely [2].
Vegetative feedstock can run the danger of secondary contamination [5, 6, 7] during technological procedures for feed harvesting (mowing, rolling, turning up, selecting for shredding, and transportation). Layer-specific contamination of vegetative bulk with objectionable microorganisms can be continued in trench silos during packing and with the entries of tractors with trailers. It results in disturbing the optimal conditions for fermentation that can impact on the forage quality [10].
The objective of the study was to investigate the initial microorganism contamination of both fodder (under field conditions) at the initial stage of harvesting with the usage of different technologies and forage after fermentation in storages for subsequent evaluation of obtained quality.
MATERIAL AND METHODS
Experiments for harvesting haylage of vetch and oat mixture were conducted on the Klyonovo-Chegodaevo experimental farm in 2012-2013 using different harvest technologies. An annual cereal and leguminous mixture in the experimental fields was made with regard for the crop yield, botanical composition, plant cut height (9 cm and 25 cm), and vegetative phases.
A grass crop bulk was packed into the half-deepened trench silo of a rectangular form with longitudinal walls and a bottom with a solid coat. Deliveries of fodder bulk were performed by the ZIL-45065 dump trucks of 5.7 tons load capacity with three-sided unloading; ramming was performed by K-701 wheeled tractors.
A haylage bulk in a trench silo was first covered with polymer film and then covered with a layer of earth to preserve from precipitation, air penetration, and freezing through. Grass crop mixture was packed into cylindrical concrete storages with smooth vertical walls,
1 ton volume each and 2 m deepened height without any farm equipment; ramming was manually performed. The bottom and top layers of grass crop bulk were insulated with polymeric film to protect from excessive moisture, and covered with a layer of earth and a metallic mantle.
Haylage feedstock was pressed using pickup presses and each roll subsequent film winding. Mowed grass crop bulk in the optimum phase was slightly dried, raked in rolls and pressed up to 400-500 kg/m3 density.
Test specimens were sampled from experimental fields and concrete round storages of
2 m3 volume each in the Physiological Yard of the All-Russia Research Institute for Animal Husbandry as well as from the trench silos on the Klyonovo-Chegodaevo Experimental Farm according to the recommended research methodologies for feed production.
Sampling was carried out according to both common methodologies for feed production and the scheme presented in Table 1 [3]. Common research methods for microbiological profile (number of mesophilic aerobic and elective anaerobic bacteria, lactic acid bacteria, pathogenic Salmonella and Escherichia, fungi, yeast, sulphite reducing clostridia), pH and toxicity in haylage specimens were used. The data obtained during experiments were biometrically processed using criteria for Student’s t-test.
Table 1 - Haylage lay out in a trench silo
Items Points of sampling
microbiological profile (quantity and identification of microorganism groups), pH, total moisture content Haylage at 1-4 m distance from the trench silo entry, top layer
Haylage at 1-4 m distance from the trench silo entry, bottom layer
Haylage at 4-16 m distance from the trench silo entry, top layer
Haylage at 4-16 m distance from the trench silo entry, bottom layer
Haylage at 16-28 m distance from the trench silo entry, top layer
Haylage at 16-28 m distance from the trench silo entry, bottom layer
RESULTS AND DISCUSSION
Analyzing the results of microbial assessment of haylage (Table 2) using different technological methods for harvesting it under similar weather conditions, it may be ascertained that the values for total microbial contamination (number of mesophilic aerobic and elective anaerobic bacteria) were higher with the plant cut of 9 cm height when compared to the cut of 25 cm height that comprised 11.90±0.11 and 9.88±0.10 (log 10 CFU/g), respectively. During biometrical processing the given values, the difference in
contamination by biological agents comprised 11.91 % in favor for technology of haylage packing with the plant cut of 25 cm height.
Table 2 - Microbiologic and physicochemical items for halage
Ol Z Method of harvesting Microbiological items, log 10 CFU/g pH Total moisture content, %
Number of mesophilic aerobic and elective anaerobic bacteria Lactic acid bacteria molds Yeast
Cut of 9 cm height
1 Feedstock (control) 9,70±0,15 3,48±0,26 2,00±0,04 2,19±0,11 5,93±0,04 74,8
2 Dried feedstock after gleaning and chopping, in 48 hours 8,30±0,24 3,00±0,20 2,00±0,05 2,60±0,06** 6,16±0,03 51,7
3 Dried feedstock, in 96 hours 8,11±0,29 3,40±0,25 not detected not detected 6,43±0,07 18,7
4 Haylage packed in a concrete ring silo 11,9±0,11 2,60±0,18 2,42±0,18* 2,60±0,18 4,42±0,06 50,2
Cut of 25 cm height
5 Feedstock (control) 8,92±0,48 2,70±0,17 2,30±0,14 2,88±0,13 5,85±0,08 72,1
6 Dried feedstock after gleaning and chopping, in 48 hours 8,83±0,09 2,30±0,17 1,70±0,1 2,19±0,13 5,91±0,07 52
7 Dried feedstock, in 96 hours 7,30±0,34 2,38±0,12 1,74±0,07 not detected 6,16±0,03 18,6
8 Haylage packed in a concrete ring silo 9,88±0,10 2,49±0,21 not detected not detected 4,62±0,05 51,1
9 Dried feedstock from film baled rolls 10,05±0,17 3,74±0,17 not detected not detected 5,68±0,02 43,6
Haylage during storage in a trench silo
10 Haylage at 1-4 m distance from the trench silo entry, top layer 14,60±0,29 3,87±0,14 2,30±0,15 3,17±0,18 4,54±0,04 66,3
11 Haylage at 4-16 m distance from the trench silo entry, top layer 14,73±0,13 3,0±0,15 2,00±0,16 3,18±0,09 5,09±0,04 68,5
12 Haylage at 4-16 m distance from the trench silo entry, bottom layer 12,05±0,23 4,9±0,28 2,00±0,07 3,04±0,04 4,97±0,05 69,1
13 C Haylage at 16-28 m distance from the trench silo entry, top layer 10,90±0,21 4,0±0,28 1,76±0,12 3,63±0,08 4,43±0,03 64,6
14 Haylage at 16-28 m distance from the trench silo entry, bottom layer 11,08±0,44 3,89±0,38 1,77±0,12 3,86±0,04 4,44±0,03 58,1
*P<0,05; **P<0,01; *** P<0,001.
Duration at the moment of taking out the test specimens made up 5 months from the moment of packing into the concrete ring silos. Selecting the rolls for silage was started with the moisture content of 60-65 % to remove the major amount of haylage bulk with the moisture content of 50-55 %. In addition, the total moisture content percentage of the test specimens was insignificantly different and comprised 50.2 % (with the cut of 9 cm height) and 51.1 % (with the cut of 25 cm height). It should be noted that there was lack of molds and yeast fungi in the haylage with the plant cut of 25 cm height, whereas their values for a sample of haylage with the plant cut of 9 cm height comprised 2.42±0.18*(P<0.05) and
2.60±0.18 (log 10 CFU/g), respectively. No molds and yeast fungi were registered in specimens sampled from the rolls with the total moisture content of 43.6 %, whereas the values for those items with the total moisture content of 58.1-69.1 % were within 1.76±0.12 and 2.30±0.15, respectively. No pathogenic sulphite reducing clostridia anaerobic microorganism and enterobacterium including Salmonella were registered with the usage of different packing technologies during the analyses of haylage samples includng feedstock samples from the film baled rolls contained the plants with 9 cm and 25 cm height of cutting.
In addition, a positive tendency of lack of toxicity in all test haylage specimens should be noted.
All the analyzed specimens satisfied the requirements of the State Standard Specification, GOST 23637-90, according to organoleptic items as follows: color, smell, and availability of mold, rot and contamination.
Sanitary and hygienic values of basic microbiologic items for samples of haylage packed into the trench silo appeared to be considerably lower than for samples of haylage packed into the concrete ring silos and film baled rolls. Ambiguity of microbiologic contamination values for specimens sampled from different levels and locations of the trench silo layout should be noted. A difference in values, mainly for a number of mesophilic aerobic and elective anaerobic bacteria, CFU/g, can be easily explained by the usage of the equipment (ramming and trailer tractor driving) during packing the feedstock in a trench silo. It might be assumed that an increase in the value for total moisture content in samples from a trench silo had an effect on the growth of yeast-like fungi which could lower a feed value. Unfortunately at present, maximum permissible standards for microbiologic items, which can have an effect on a haylage category are not taken into consideration and consequently not defined in enactment certificates to assess feed value and safety. Mold content in haylage is not permissible in the proposed project as follows: Veterinary Regulations and Safety Standards of Feed, Feed Additives and Feedstock for Feed Production according to the Veterinary Rules and Regulations VetPiN 13-5-01/0101 2003, item 2.1.1.3. Analyzing the results of the work, it may be assumed that the values for a mesophilic aerobic and elective anaerobic bacteria number defining the total microbial contamination within 8 log 10 and 10 log 10 CFU may correspond to mold and yeast lack. Relying on the facts of the study, the items of a number of mesophilic aerobic and elective anaerobic bacteria, mold and yeast-like fungi are recommended including into the feed assessment regulations.
Ascertained microbiologic values should be open for consideration and supplemented as required by feed and feedstock safety developments as well as fodder harvest and forage production specificity.
CONCLUSIONS
1. Halage packing and storage technologies can impact on bacterial contamination and haylage quality. The technology of haylage rolls was the best among the tested technologies.
2. The estimated values for total contamination, which have no effect on haylage quality, can be within 1108 and 11010.
3. Height of cutting to a higher grass plant level (25 cm height) during haylage harvesting can make it possible to harvest the first category leguminous and cereal haylage possessing 13 % protein on a dry matter basis, not over than 29 % crude cellulose on a dry matter basis, not less than 55 mg/kg carotene on a dry matter basis, and lack of butyric acid.
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