With the icy weather we had last week and snowstorms this week, livestock producers are dealing with some pretty stressful situations with their cattle herds, many of which are just starting to have spring calves.
Dr. Michelle Arnold, DVM, and University of Kentucky ruminant Extension veterinarian at the UK Livestock Diagnostic Lab has provided information that should be of benefit to cattle producers.
The cold, muddy conditions resulting from the numerous ice and snow events this year mean cattle will require substantially more energy in feeds to maintain their body weight and produce milk until grass is growing again. If hay quality is poor, rained on while curing, and/or baled with enough moisture to support mold growth, supplemental feed will be required to meet basic nutritional needs.
The body of the animal has several defenses against cold. The first is the hair coat which grows longer in winter and, when fluffed up and dry, helps conserve heat and repel cold. Under winter conditions, if an animal’s coat cover is wet and muddy, then energy requirements easily can double, particularly if the animal is not protected from the wind.
Cold conditions are not too difficult for cattle but when rain and wind are added, heat loss is multiplied several times because warmth is conducted away from the body through evaporation, similar to what we know as the “wind chill factor.”
Additionally, loss of backfat means less insulation under the skin so heat also is lost when lying on wet, cold ground. If producers are not supplementing cattle with adequate energy and protein sources, hay of poor nutritional quality will not provide sufficient nutrition to meet the animal’s basic requirements.
This will result in depletion of body fat stores, followed by breakdown of muscle protein and finally death because of insufficient nutrition.
The producer first may notice a cow getting weak in the rear end and may mistake this for lameness. Later she is found down and is unable to stand. Death follows within a day or two after going down. Multiple animals may die within a short period of time.
Despite having had access to free choice hay, these cattle have died from starvation. Although hay may look and smell good, unless a producer has had the hay tested for nutritional content, he or she does not know the true feed value of that harvested forage.
It often is difficult for producers to bring themselves to the realization that cattle actually can starve to death while consuming all the hay they can eat – especially if crude protein levels are in the 3 to 4 percent range and TDN is less than 40 percent – as is not uncommon in some late-cut, overmature, rained-on hay.
Inadequate crude protein in the hay (below 7 to 8 percent) means there is not enough nitrogen for the rumen microflora “bugs” to do their job of breaking down fiber and starch for energy. Digestion slows down and cattle eat less hay because there is no room for more in the rumen.
Cattle are expected to eat roughly 2 to 2.5 percent of their body weight in dry matter but this may fall to 1.5 percent on poor quality hay. Many producers purchase “protein tubs” varying from 16 to 30 percent protein to make up for any potential protein deficiencies, but fail to address the severe lack of energy in the diet.
In the last 60 days of pregnancy, an adult cow requires feedstuffs testing at least 50 to 55 percent TDN (energy) and 8 to 9 percent available crude protein while an adult beef cow’s needs in the first 60 days of lactation increase to 60 to 65 percent TDN, and 10 to 12 percent available crude protein. Cold weather and mud will increase these requirements. In addition to malnutrition in adult cattle, inadequate nutrition and weight loss severely affect the developing fetus in a pregnant cow. “Fetal programming” of the immune system of the developing calf during pregnancy will not progress correctly without the correct nutrients and trace minerals. A weak cow may experience dystocia (a slow, difficult birth) resulting in lack of oxygen to the calf during delivery, leading to dead or weak calf.
Calves born to deficient dams have less “brown fat” so they are less able to generate body heat and are slower to stand and nurse compared to calves whose dams adequate nutrition during the last 100 days of pregnancy.
Check out the UK Beef Cow Forage Supplement Tool at forage-supplement-tool.ca.uky.edu. Enter the values from your hay test and stage of production of your cows (gestation or lactation) to find a supplement that will work for you. The UK Beef Cow Forage Supplement Tool was produced by Extension Specialists in the University of Kentucky Department of Animal and Food Sciences, and serves as a tool to estimate forage intake and supplementation rates. Remember actual feed/forage intake and body condition should be monitored throughout the winter and early spring.
Cattle also should have access to a complete mineral supplement – white salt and trace mineral blocks are not sufficient – and clean drinking water at all times.