Photosensitivity occurs due to the effects of Brassica crops (Turnips, Rape and Kale) on the liver, making the cow release a large amount of phylloerythrin (chlorophyll) into her blood, which is more sensitive to the UV rays of the sun.  

Early signs may show on the skin and the teats of the cow resulting in sore, scabby, sloughing teats and weeping areas of the skin, usually confined to non-pigmented (white) areas. There is usually some discomfort, and cows may present showing signs of colic (kicking out etc).

If you notice a cow with sore teats or colic that is on Brassica crop, the best idea is to remove her from this crop and provide her with shelter from the sun if possible. Filtabac cream should be applied to affected teats, and come and speak to our Retail team about sunblock options for larger areas of skin. Antihistamines and anti-inflammatories may be of benefit. If a lot of your herd is affected then try reducing the amount of Brassica crop they are eating.  This can be done by not putting them right on crop after milking so they don’t gorge themselves when they are hungry, or by offering them some good quality hay or silage, which is high in fibre, so they don’t consume as much crop.  

Antibiotics are ONLY warranted if the skin becomes infected and should this or other complications occur please contact your veterinarian.

CUD Newsletter - April 2102