Milk cows experience high levels of stress at the time of calving and the weeks that follow. More often than not this extra stress manifests itself as metabolic problems such as milk fever, mastitis, retained placenta, ketosis, displaced abomasum or laminitis.
Four challenges that seem to stand out as being the most problematic for dairy herd managers and nutritionists are keeping the immune system strong, maintaining dry matter intakes, avoiding ketosis and maintaining the calcium status of the transition cow.
1. The cause of immunity suppression in close-up and fresh cows is poorly understood even though it has been studied for years. Current research suggests that it is a combination of hormonal and metabolic factors. Most likely, all four challenges are interrelated, and a failure to properly manage any one of these areas may lead to failure in another.
There are a host of things that can go wrong in the transition period that will affect immunity and energy status that, in turn, set off the metabolic challenges that often open the door to infectious diseases, as well. The solution to managing transition cows effectively in order that they make that “transition” to a high-producing lactation is mostly about proper and timely herd management. A significant part of that management involves nutrition.
2. It’s well known that cows that are just a couple of days away from freshening reduce their dry matter intakes – probably a hormonal response – prompting the beginning of a negative energy balance. That negative energy status continues and only increases after a cow freshens so that she is unable to consume enough feed to meet nutrient requirements. As her feed intake drops, she must begin mobilizing her body fat reserves for part of her energy needs, and the excessive breakdown of fat in the liver can lead to ketosis.
3. Ketones in the body compete with glucose and are known to be poorly utilized by key immune cells, thereby affecting immunity. A compromised immune system opens the door for infections such as mastitis and metritis. In addition, when the cow is subjected to stress events such as frequent re-groupings or social isolation in a maternity pen, cortisol, a known immune suppressant, will be produced.
4. Long recognized for its key function in proper muscle function and milk fever, calcium is now known to have a direct association with immune cell function. When white blood cells respond to a bacterial assault such as mastitis, calcium plays a key role in the activation of immune cells. Not only will low calcium (hypocalcemia) affect the closure of the teat sphincter after milking, when bacteria invade the udder, the cow’s immune response is reduced as well. Both clinical and sub-clinical hypocalcemia will also cause an elevation in cortisol levels.
Low calcium will also prevent the rumen from working properly or the involution of the uterus after calving, again setting the stage for a displaced abomasum (DA) or a retained placenta and metritis. Research conducted some years ago showed that a cow that experienced milk fever was five times more likely to come down with mastitis.
Even though this cause-and-effect association of transition nutrition, immune function and metabolic and infectious diseases has been known for many years, the incidence of these disorders persists in U.S. dairy herds. (See Table 1.)
This summary suggests that there are dairies out there that do a very poor job of controlling several of these disorders. Cows are not being adequately cared for during both the close-up period and after they are fresh. This poor management paints a bad picture for dairy profitability and animal husbandry. Proper management and care of the transition cow falls squarely on the shoulders of the dairy farmer and his management team.
Jim Smith, a manager at the Cushman Dairy Farm, in Franklin, Connecticut, began incorporating a close-up group as part of the herd management more than two years ago. Smith explains that one significant area of improvement that he can definitely attribute to the close-up ration is the dramatic reduction in displaced abomasums (DAs). “We used to have probably 12 percent DAs in the herd. Now we’re down to maybe 3 percent,” Smith says. Milk fevers, retained placentas and mastitis are also at low levels in the herd.
The close-up group now has its own specific ration compared to before, when all the dry cows were grouped together. The ration formulation does not include anionic salts. It is corn silage-based with 1.5 pounds of processed straw added and supplemented with a grain mix that’s formulated to keep starch about 20 percent of dry matter and NFC below 40 percent dry matter.
Until recently cows were spread between two different locations, and Smith notes this has sometimes been a challenge when trying to manage the herd properly. In 2009, a new freestall barn will be ready so all cows – dry and milking – will be together on the same site. Currently, all cows calve in the same pen with a bedded pack. Part of the new housing facility will also have maternity pens.
Cushman Dairy milks more than 820 cows, three times per day in a rotary parlor – the only rotary parlor operating in Connecticut. According to Smith, his close-up group averages 50 to 60 cows most of the time. He tries to get cows into the close-up group at three weeks prior to freshening. When cows are moved to the pre-fresh pen, they’re given a shot of vitamin E and selenium. When they freshen they get another shot of vitamin E and selenium as well as vitamin B, a calcium pill and a rumen enhancer.
Ketosis is seldom a problem for Smith’s herd. He believes that making sure there’s feed in front of the fresh cows all of the time is a major factor in keeping ketosis to a minimum. As with most herds, the cows prone to ketosis are usually the ones that have taken too long to get bred back and wind up with too much body condition when they freshen for the following lactation.
Smith will agree that the foundation of a successful dairy operation is a herd that’s made up of healthy, high-producing cows that have minimum metabolic issues and will breed back quickly, avoiding gaps in the breeding cycle. That foundation includes excellent transition nutrition and management. Having a close-up program and with its own diets will significantly aid in reducing metabolic problems. PD
John Hibma is a freelance writer in South Windsor, Connecticut.
John Hibma
Nutritionist
