Mary Allen
Light is important – for humans as for all mammals. Various metabolic functions are due to vitamin D. Light also affects fertility in rabbits.
The Animal Welfare Act prescribes minimum natural daylight of 15 lux. 1 lux corresponds to the light intensity of a burning candle at a distance of one meter. With such brightness, a grower should still be able to read the daily newspaper. It is even better to have different light intensities in the barn so that the animals can choose their own preferred location.
Daylight is definitely preferable to an artificial light source because ultraviolet radiation can kill germs. However, it should be noted that not the entire spectrum of UV radiation can penetrate through the window glass. A grid instead of a window is more advisable in terms of lighting technology.
Rabbits are crepuscular animals; during the day they tend to rest. Accordingly, their sense of sight is relatively sensitive, but they still need daylight to feel comfortable and to be able to develop well.
The Light Promotes Performance
The German researcher Meike Schüddemage has studied the influence of light on the fertility of females and bucks. She compared the results under natural light, an 8-hour, and a 16-hour light program and concluded:
- The conception rate (= ratio of the number of pregnancies to inseminations or jumps of the bucks) could only be slightly increased with artificial light.
- With an artificial light of 16 hours, the highest number of pups born overall could be achieved compared to artificial light with eight hours; most young animals were also weaned under the influence of 16-hour artificial light.
- The average suction frequency was 1.14 suction acts with the 16-hour artificial light program and 1.41 suction acts with the 8-hour artificial light program.
In her report, Schuddemage noted that the rabbits’ suckling activity follows a special rhythm and that the light change from bright to dark gives the impulse for suckling. With the 16-hour artificial light program, 28.1 percent of all sucking acts took place in the first hour after the light was switched off. The results also showed that the suckling of the young mostly takes place in the dark phase.
The influence of light also influences the development of sexual activity; the increase in daylight length in spring caused an increase in jumping activity in bucks.
Does seasonal influence (temperature and humidity) affect fertility parameters? Humidity and temperature were measured in a group of rabbits under constant conditions and 14 hours of light over a period of almost two years to find out whether these factors have an impact on fertility.
The willingness to cover showed a seasonal course over both test years. High values were reached in February with 97.2 percent, low values in September. The highest conception rates were also measured in the spring months of March and April. Neither stable climatic influences nor a seasonal dependency could be determined for the litter sizes and loss rates. On the other hand, individual animal and litter weights (standardized to an average litter size of seven) showed significantly better values in the second half of the year.
In these studies, only the conception rate shows a clear dependency on the stable temperature; Willingness to breed as well as individual animal and litter weights showed a seasonal trend.
Karl Weissenberger writes in his book “Reproduction and Breeding Procedures in Rabbit Breeding” that every breeder should consider how he can bring better lighting conditions into the usually dark stables in winter. It is beneficial to prolong the short winter days with adequate lighting; he recommends artificially extending the day to 14 hours.
Rabbits Perceive Light Differently
But beware! Light is not just light. Since our alternating current has a frequency of 50 Hz, our light flickers at a frequency of 50 Hz per second. We humans don’t perceive this flickering, but rabbits, who have much better perceptions, perceive the light as flickering. DC lamps are better.
Much more than animals, plants depend on sufficient light. They need it to produce oxygen, which in turn is needed to build up the nutrients they need for growth. It’s called photosynthesis. It is operated in plant cells with chlorophyll, the green leaf pigment. With the presence of sunlight, water, and carbon dioxide, grape sugar (glucose) and oxygen are produced. This glucose can be processed into starch.
Photosynthesis is therefore important so that there is enough food available for our animals every day. Various scientists want to solve the energy question with principles similar to those of photosynthesis. Scientists around the world are researching solar cells that mimic the photosynthesis of plants and produce synthetic fuels such as hydrogen from sunlight and water. Empa researchers have modeled such a photoelectrochemical cell on the moth’s eye and thereby drastically increased the light yield (source: ee-news, June 2014).
Photosynthesis depends on factors such as light, temperature, humidity, fresh air supply with carbon dioxide, and sufficient water. With one exception, these factors are also crucial for successful animal husbandry; only that instead of carbon dioxide there must be enough oxygen.
The United Nations recently declared 2015 the “International Year of Light”; also an occasion to deal with the topic of sustainability.