The longest day has been and gone and already family and friends are discussing how the nights are drawing in!
For dairy producers that have improved upon removing barriers from milk production and reproductive success, such as cubicle design and feed face optimisation, manipulation of light might be the next opportunity to address before autumn and winter draw in!
A number of studies have shown that dairy cows which experience a longer photoperiod, could increase milk production by between 5 and 16%, with an 8% response being typical. Further benefits have also been described including improved oestrus expression, improved submission rates and increased lying times.
Light reception in the eye inhibits an enzyme used to synthesise melatonin in the pineal gland. When there is sufficient light the cow’s body will signal to produce less melatonin, and when it is dark melatonin levels increase. Essentially cows have an “internal clock” set by melatonin production. Increased melatonin concentrations within the cow can affect other hormone concentrations, such as decreasing Insulin-like Growth Factor-1 (IGF-1). Increased IGF-1 production in the cow is associated with increased milk production. So by manipulating the cow’s “internal clock” by increasing day length, melatonin concentrations decrease resulting in higher levels of IGF-1 and so increasing milk production. Long-day lighting usually increases dry matter intake by up to 6% to supply the extra nutrients required for the increase in milk production and the initial response can take up to two to four weeks to be seen. However to see a full response it is critical that cows also have an uninterrupted dark period.
The intensity of light which cows are exposed to is just as important as the length of the lighting period. Broad rules of thumb are a minimum of 200 lux during light periods and less than 50 lux, lux meters are relatively in expensive and a great way to determine light levels within sheds. Importantly check lighting at cow level across the shed and consider if there are areas at risk of shadowing negating the benefits you are making when mounting new lighting. Both the resting and eating areas for cows must be provided with adequate light.
There is a vast range of lighting solutions available including incandescent lights, fluorescent lighting, high pressure sodium lights and others and the right solution for your farm will depend on a balance of size of building, running costs and environmental conditions. Improved lighting often has more than cow benefits as staff often comment on the benefit by improved lighting conditions to perform tasks more easily. Timed systems work well reducing the reliance on busy staff to turn lights on or off, and crucially if working with automated systems ensure the light sensor is within the shed and not outdoors!
Further research suggests that lighting of dry cows may also be an important area to review, where the converse to milking cow lighting is true – dry cows need a short photoperiod! However the most practical solution for most farms is probably keeping dry cows housed under natural light conditions and extending the photoperiod for milking cows all year round.