Lameness in Dairy Cows This Year

It seems that some dairy farms have experienced a greater than usual incidence of lame cows this season. There’s probably several reasons for this, including the unusually wet spring and summer, but attention has also focused on certain nutritional aspects that can influence the strength and well-being of cows’ hooves.

Early on this spring, there were reports that many cows in some herds were foot-sore; not acutely or severely lame, but more tender on their feet. The most likely cause of this was that they were suffering from laminitis, an inflammation of the tissues of the hooves, brought on by a surfeit of dietary protein and carbohydrate. Laminitis is similar to “founder” in horses, and is typically associated with ponies that are getting too much feed and not enough work. The diet induces changes to the circulation of blood in the feet that results in congestion and abnormal clotting. This then leads to swelling and damage to sensitive tissues in the feet, the lamellae, and causes considerably pain when standing or walking.

Laminitis in cattle is common in countries like the USA where cattle are largely grain-fed, and results in significant economic loss from reduced lactation and reproductive performance. Its not been so much a problem in New Zealand, but may be on the increase as more supplemental feed is used or we get an extended flush of grass growth during spring. If warmer, wetter springs, such as occurred this year, become a regular occurrence, it is likely that laminitis could become more of a problem in New Zealand dairy cows.

The problem with even mild laminitis is that it tends to weaken the “white line” of the hoof. Then, coupled with the long distances our cows often have to walk each day along races that may not be in the best condition, this “white line” weakness predisposes to bruised soles and foot infections. The result can be acutely lame cows and all the hassles that go with them.

However, the onset of laminitis can be prevented or minimised by attention to certain nutritional factors. It may not be possible to modify protein or carbohydrate intake of cows in New Zealand as easily as can be done under feedlot conditions, but there are a few things we can do.

Low fibre intake contributes to laminitis, so feeding some mature hay when lush grass prevails can be helpful. Another approach is to consider the use of dietary buffers in early lactation to avoid rumen fermentation patterns converting excess protein into energy. It is probably the high protein/low fibre content of our spring grass that mainly initiates laminitis under NZ conditions.

Another approach is to consider the nutritional factors that are necessary for maintaining good hoof health and hardness. Important for this are various trace minerals. In particular, zinc plays a major role, as it is essential for production and maintenance of keratin, the protein that comprises most hoof tissue.

Regular zinc supplementation, especially in a form that is well absorbed such as amino-acid complexed zinc, has been shown to reduce the incidence of hoof problems in herds prone to laminitis. As well, cows need to have adequate copper reserves because copper is also necessary from the synthesis of keratin.

So if zinc and copper levels are sub-optimal, hooves tend to be softer and weaker. This makes them more susceptible to stone-bruising and, if laminitis occurs, to “white-line” injury and subsequent foot infections.

But it takes time for mineral supplements to strengthen and harden hooves. Horn tissue grows slowly and it may be six months or more before hooves that have become soft due to zinc or copper insufficiency, develop the hardness that will help reduce the incidence of lameness. If you suspect laminitis has contributed to lameness problems in your herd and want to supplement with zinc or copper to help prevent it this coming spring, you need to starting the supplementation now - not when the problem occurs.