Researchers think the production increase may result from an increase in an insulin-like growth factor (IGF-1), which is a hormone involved in the secretion and continued production of milk and decreased levels of melatonin.
Melatonin is the signal the cow uses to read the length and intensity of daylight. The cow then stimulates the liver to release more IGF and give more milk.
The increased photoperiod will gradually increase milk yield over a 14-day to 28-day timeline. The research says that photoperiod does not substantially affect fat or protein content of milk.
Daily exposure of 16 to 18 hours of total light is what researchers say is needed. Why not just leave the lights on for 24 hours then?
Researchers also know that six to eight hours of darkness is needed to re-set the natural “time clock” in the cow. If a cow does not get this period of total darkness, she will lose her ability to respond to the extra lighting you have provided her.
If you need lights on for working during the needed “dark time,” use low-intensity red lighting. This type of lighting will not upset the photoperiod response.
Producers should set lights up on timers and not rely on manual implementation so that they are guaranteed the correct time needed.
It is also critical to provide enough light intensity for the cows. In order to ensure this, you must have someone with a light meter measure your lighting.
An intensity of 38 to 60 foot-candles is required, which means you may have to switch the lights on during very dark overcast days.
Place the lights over the areas where the cows spend the most time, such as the feeding area and lying areas. Lights may also dull over time due to contamination with dirt and dust or simply wearing out.
Ask your dairy consultant to test your lighting levels in your barn, using a light meter, to see if you’ve reached the requirements needed to take advantage of this money-making idea.
Remember that last year’s readings may not be the same this year. Why? Lights dim with age, and dirt and dust can cover the lights, reducing intensity.
What is the best type of lighting?
Several types of lighting are available. Florescent lights may be best for low-ceiling barns, such as older tiestall barns, and should be equipped with a cold-weather, rapid-start and moisture-resistant ballast.
In barns with higher ceilings, it is recommended to use metal halide or high-pressure sodium lights. Both types should be equipped with a reflector and refractor for optimum performance.
New research shows that blue LED lighting is the most effective in suppressing melatonin production and therefore increases the levels of prolactin and insulin-like growth factor, which improve mammary function (i.e., more milk).
Interestingly, recent research also points towards benefits to the dry cow receiving only six to eight hours of lighting per day.
These cows calved with less metabolic problems and gave 2.5 kilograms more milk than dry cows receiving the longer daylight period. Unfortunately, this research will likely cause logistic problems in most barns.
Perhaps this all relates back to the natural calving schedule of spring calving before domestication?
Some very recent research has indicated that reproduction may also be affected by daylight intensity. Is that why cows seem to breed better in early to late springtime?
In summary, because of all the research of the benefits now available on this topic, dairy producers need to take a serious look at meeting the lighting need of the modern dairy cow in order to make the most of the economic advantages of supplemental lighting. PD
Tom Palen
Nutritionist
Triple P Consulting
