Although it does not seem stable lighting has always been a challenging proposition.
Illumination of Stables for Dairy Cows Ing. Petr Hutla, CSc. 1 , Lukáš Vyhlídko2 , Ing. Josef Šimon1 Buildings meant for the production of livestock products, especially in the raising of cattle, are very sensitive as to the technical solution chosen, as regards illumination. It’s about a repeated duplication of a similar installation, for these buildings are typified as to their dimensions and technical equipment.
A quality illumination assembly ensures a suitable work environment for one, and otherwise the necessary physiological illumination for livestock. Besides providing for the fruitful welfare of animals, the illumination also has a significant impact on yield. The building of modern stables for high-yielding dairy cows started shortly after the year 2000 in the Czech Republic. These stables are designed as modular buildings, whose lengthwise modules allow for the placement of stalls with of width of at least 1,200 mm.
This is exclusively about free stabling, most often having been built as six-row freestanding stall stables. These buildings are designed with a suspended steel frame, or with a system with two rows of support columns. Additionally, wooden construction or a combination of the two systems is used. A stall for a single dairy cow is most often 1,200 mm wide and 2,400 – 2,500 mm long. The span of the whole structure is typically 32 m and allows for the placement of a dung corridor next to the rows of stalls, a feeder, displacer corridor and passable feed corridor. A view of this described stall space is depicted in picture 1.
Besides its protective function, the roof of the buildings also provides for suitable ventilation of the space and that's why it is often fitted with a ridge-wise aerating slit. Daily illumination is ensured by light penetrating strips in the roof’s cover.
Requirements for the illuminating assembly result primarily from Czech Technical Standard EN 12464-1 (Lighting and Illumination) - illumination of work spaces – part 1: Indoor work areas. For stables for livestock, it is required to maintain illumination of Em = 50 lx, evenness of illumination of Uo = 0.4; the index for glare UGRL isn’t prescribed and the index Ra > 40. More detailed requirements are listed e.g. in [4]. In the stables for dairy cows, it is required to have graduated illumination, i.e. The space where the animal moves has an illumination of Em = 50 lx and where feeding Em = 100 lx. Sufficient illumination at the place of the feeding of dairy cows follows from the requirement to achieve the maximum consumption of feed per animal, which directly correlates with its milk yield. A sufficient amount of light at the feeding table raises the frequency the animal approaches the gully, and therefore its appetite.
Pic. 1. The interior of a 6-row modern stable for dairy cows with a central feed corridor
Light Sources and Lighting The correct choice of a light source is the basic pre-requisite for a successful design for each illumination assembly. It is necessary to correctly choose, keeping in mind these qualities: - specific output of the source, - productive lifetime, - price, - suitability with regard to the principle of a lamp assembly. To illuminate stables for dairy cows, it is most suitable to use fluorescent bulbs. Earlier views on the unsuitability of fluorescent light bulbs in buildings with livestock production have been eclipsed, for modern fluorescent lighting is highly resistant to the influences of the stable environment and when using electrical ballasts, a large number or earlier necessary contacts are eliminated, which had been the cause of operational malfunctions. When used as part of agricultural factories, it is common to use T5 linear fluorescent light bulbs with a width of 16 mm. Structurally, they are made in the lengths of 1,149 mm and 1,449 mm. A suitable colour of light is a neutral white, with replacement temperature chromaticity of 3,500 – 5,300 K. The Index of colour rendering Ra is generally within the range of 80 - 89. Lighting which is suitable for use in stables is continuously being technically perfected, and its operational reliability is growing. Earlier opinions on using fluorescent bulbs in buildings of livestock production have significantly changed, especially an increase in their reliability.
Pic. 2. Fluorescent lamp Prima 245 ABS AC VU PG ET5 ES, made by Trevos plc. Fluorescent light bulbs almost exclusively use electronic ballasts, so the number of contacts has decreased, which had been a source of malfunctions. Presently, this is the common cover for IP65 and IP66 lamps, which, along with additional technical measures, ensures a high level of protection for the inner parts of the lamps. Exclusive use of fluorescent lamps in stables follows from, above all, the possibility of hanging heights which are in the lowest parts of the building, i.e. ca. 3 m. Due to evenness of lighting, it is therefore necessary to use sources with lower input power. Lamps must be chosen so that they have enough coverage, optimally IP66, and are made of materials that resist a mildly agressive environment, containing ammonia, respectively other detrimental compounds.
Pic. 3. Distribution of the luminosity of the Prima 245 ET5 lamps, made by Trevos plc. An example of a suitable lamp is that of the Prima 245 ABS AC VU PG ET5 type from Trevos plc (pic.) 2). The lamp is fitted with T5 bulbs; the housing of the lamp is made from ABS plastic (Forsan) and the lamp cover from acrylate polymer (AC). The lamps are fitted with electronic ballasts. Their advantage when compared to the T8 electronic ballasts is that the consumption of electrical energy is up to 10 % lower, and up to 40 % lower than using the conventional T8. A possible variant is the design with the T5 electronically dimming ballast: - with a 1 to 10 V interface – analogue-signal control, - with a DALI interface – controlled by the DALI digital protocol or by the Touch DIM function.
This method allows for the dimming of the light assembly in relation to the natural light and the time-dependent switching on and off of the lamps. When a minimal amount of illumination is required at night, it is possible to operate the ballast for attaining safety illumination with a luminosity of several lux. In order to enable the dimming mode of the lighting assembly, it is necessary to use an adapter, which can be either directly connected to the lamp, or can be connected by an independent cable.
Table 1. Light-technical parameters of the assembly – illumination above the feeding table
Note: The estimated interval for cleaning lamps is twelve months.
Using an adapter is suitable for automatic switching on/off when the lighting is switched as to attain the required illumination of daylight. When installing lamps in the mildly aggressive environment of an object of livestock production, it is extremely important from the standpoint of operational reliability for preventing the entering of light into the lamps with sufficient covering. This is attained using a ventilation plug, e.g. BVPB – 01 type. A plug of the M12 x 1.5 size is made from polyamide and eliminates the presence of condensing vapour in the lamp. It is also necessary for the safe ensuring of sealing the lamp and to exclude strain, to fit it with a screw-able bushing, e.g. PG 13.5. Lighting of stables for dairy cows (252), width 32 m – illumination above the feeding table This deals with a typified stable with a width of 32 m and a length of 72 m.
Pic. 4. Arrangement of lamps in stables for 252 dairy cows, lamps above the feed corridor – sectional view
The stable has 6 rows of stalls and a symmetrically placed feed corridor. The height at the lengthwise walls is 3.5 m, the roof has an angle of 22°, the greatest height is 9.95 m. It is supposed that the factor of reflection of the roof is 0.4, walls have 0.5 and the floor has 0.3. 39 Prima 245 ABS AC VU PG ET5 ES lamps by TREVOS plc are used here, which are fitted with OSRAM FQ45W/840 ES G5 bulbs, Lumilux T5 HO Cool White. The curves of luminosity for the given lamp are shown in picture 3. The bulbs have a light flow of 4,900 lm, a life of 24,000 h, Ra of 80. The total light flow of the lamp is 9,800 lm. The distribution of the lamps is shown in pictures 4 to 6. They are distributed in three rows, 10 m apart from each other. The hanging height of the lamps of the middle row is 8.5 m. The outer rows have 5.5 m. The space between lamps of the outer rows is 9 m, in the middle row it is 3.18 m.
The light-technical parameters of the assembly are shown in table 1. Lighting of stables for dairy cows (252), width 32 m – illumination above the feeding table The difference in this case is the method of lighting the feed corridor. The number of lamps is 36. The distribution of lamps is shown in pictures 7 to 9. They are located in four rows, symmetrically to the lengthwise cross-section of the building. Two rows of lamps above the feeder are 4 m apart from each other, with the distance from them to the outer row being 8.825 m. The distance between the lamps in the rows above the feeder is 7.2 m, in the outer rows it is 9.257 m. The hanging height of the lamps is 5.5 m. The lighting-technical parameters of the assembly are shown in table 2.
Conclusion Both methods of illuminating the stables, which differ regarding the placement of the lamps in the middle part of the space, are suitable for the given space. Their use to a good extent depends on the subjective choice of the user. When installing two rows of lamps at a lower hanging height, the overall input of the illuminating assembling is lower by 7%. When implementing a row of lamps along the ridge of the roof, the space of the stable isn’t changed, and this method is therefore more suitable for suspended steel frame constructions. Table 2. Light-technical parameters of the assembly – illumination above the feeding table.
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