Recently, I was talking to a feed mill operator I occasionally do some beef nutritional work, and he told me many customers are requesting the best level of zinc added into their cattle mineral. We realize many pastures and harvested forage from this summer’s drought might likely be zinc-stressed, so we made sure to formulate cattle producers’ minerals with a sound level of zinc in order to prevent zinc deficiencies in cattle.
National Research Council (NRC) recommendations call for beef cattle to consume between 20-40 mg/kg diet (while dairy cattle require more zinc; 40 mg/kg zinc diet). Factors such as age of the animals, growing and production status, stress and disease challenges are taken into account and often call for additional zinc in cattle mineral for a few special customers.
Zinc nutrition for cattle is important as it is involved in energy metabolism, protein synthesis, DNA functions and the internal workings of cattle immunity.
With so much good science, the benefits of feeding zinc has several examples such as:
- Strong hooves. Because zinc is part of specific enzyme systems involved in epithelial (skin) formation and repair, feeding extra dietary zinc is thought to strengthen cattle hooves, particularly under harsh field and housing conditions. For example, Illinois State University fed a group of replacement heifers an additional 200 mg/hd/d in the form of zinc methionine (organic zinc) for 75 days and had fewer cases of foot rot, heel cracks, claw dermatitis, and laminitis. Stronger hooves provide a stronger barrier against pathogenic microbes that commonly work their way into cracks in cattle hooves and once inside, they cause foot disease.
- Less sickness. Texas research demonstrates that serum zinc levels decrease dramatically when drylot beef cattle were diagnosed with respiratory tract infections caused by IBR. On the other hand, some Midwest research demonstrates when dietary zinc is supplemented in a more bioavailable forms (such as chelated zinc); less morbidity (sickness) among long-trucked receiving feedlot cattle was reported. Similarly, zinc has been shown to fight mastitis by stimulating an immune system response in infected udders.
- Fertility. Zinc has been shown to play an essential role in many cow reproductive functions such as strong estrus cycles, improved conception rates, promotion of normal post-partum uterine involution, and reduction of metritis. In the bullpen, zinc plays in a role in male fertility; essential role in the sperm production, and increased circulating male hormones such testosterone.
I remember about five years ago, when a beef producer grazing about 100 beef cows in swampy pastures had a real problem with lameness in his cattle (such as the Illinois case, above). The good news was that it wasn’t foot rot, but many cows suffered from cracked and bruised hooves. I suggested he feed zinc-methionine at four grams per head (formulated into a commercial beef mineral) daily for the rest of the summer and until the ground freezes. At the end of the four months, he told me that the cow herd had got over this crippling problem.
It’s a good demonstration on the power of zinc in cattle nutrition, whether you are feeding beef cows, replacement heifers, bulls or calves. It also a good reminder that zinc as well as other essential nutrients will only “work” in cattle when; they receive a good level, it’s in a bioavailable form and the zinc is balanced with other nutrients in the cattle diet. As a result, overall good nutrition as well as good zinc status is assured.