K-State Research and Extension

“How Much Water Does a Cow Need?”

By Justin Waggoner, Ph.D., Beef Systems Specialist

Most cattle producers fully understand the importance of water. After all, providing an adequate supply of clean, fresh water is the cornerstone of animal husbandry and there are very few things that compare to the feeling of finding thirsty cows grouped around a dry tank on a hot day. Water is important, and in situations where the water supply is limited or we are forced to haul water, one of the first questions we find ourselves asking is, “How much water do those cows need?” The old rule of thumb is that cattle should consume 1-2 gallons of water per 100 lbs of bodyweight. Accurately determining the amount of water cows will voluntarily consume is difficult and is influenced by several factors (ambient temperature, moisture and salt content of the diet, body weight, lactation, etc.). Water consumption increases linearly as ambient temperature increases above 40° Fahrenheit such that cows require an additional gallon of water for every 10 degree increase in temperature. Additionally, lactation also directly increases the amount of water required by beef cows. The table below summarizes the daily water requirements of beef cows of several different body weights, milk production levels and ambient temperatures.

The daily water requirements of beef cows represented are estimates and water consumption varies greatly during the summer months when temperatures exceed 90° Fahrenheit. Therefore, these recommendations should be regarded as minimum guidelines.

For more information, contact Justin Waggoner at jwaggon@ksu.edu.

“What’s in Today’s Feedlot Diet?”

By Chris Reinhardt and Justin Waggoner, Ph.D., Beef Systems Specialist

The commercial cattle feeding industry is incredibly diverse in many ways. A recent survey of consulting nutritionists conducted by Samuelson et al., (2016) gives us some insight into the feeding and management practices of the cattle feeding industry. This survey summarized responses from 24 consulting nutritionists that service in excess of 14,000,000 cattle annually. As expected, the primary grain used in both receiving and finishing diets was corn. However, the most commonly reported secondary grain used was wheat. The most common processing methods were steam-flaking and dryrolling. The typical grain inclusion was 60% or less for receiving diets and 34.8% of the respondents reported an inclusion of 60-70% grain in finishing diets with a range of 50-90%. The reported range in grain inclusion of finishing rations is likely attributed to the use of by-product feedstuffs. The most commonly used by-product in both receiving and finishing rations was wet distiller’s grain. Alfalfa was the most common roughage source used in receiving diets (58.5% of responses). In finishing diets corn silage was the primary roughage source used (37.5% of responses), followed by corn stalks (29.2% of responses) and alfalfa (20.8% of respondents). The majority of nutritionists in the survey recommend an energy content 0.68-0.70 Mcal/lb of Net Energy for gain and 13.4% crude protein in the finishing ration.

For more information, contact Justin Waggoner at jwaggon@ksu.edu.

“Body Condition Scoring: It’s About More than the Score”

By Justin Waggoner, Ph.D., Beef Systems Specialist

Body condition scoring is one of the most valuable management tools at the disposal of the cattle manager. This one number gives us a direct indication of an individual cow’s previous plane of nutrition and future reproductive capability. Although the individual body condition scores are important, we don’t necessarily manage individual cows, we manage groups of cows. Thus it is important for us to look beyond the individual scores and look at the distribution of body condition scores within the herd.

If we have a herd (Herd 1) with an average body condition score of 5 that is essentially characterized by the classic bell curve, with a few thin cows (3.5’s), the bulk of cows in the middle (4’s and 5’s) and few over-conditioned cows (7’s) everything is good. Alternatively we could have a herd (Herd 2) with an average body condition score of 5 that is essentially the result of a few thin cows (3’s) and some over conditioned cows (6’s and 7’s). Body conditioning scoring also has more value when it is done on the same group of cows at multiple times during the production year. If Herd 2 was scored at calving and had been previously scored at weaning and had an essentially normal distribution (similar to Herd 1). We need to ask ourselves what happened. Did we change anything? Although these examples are somewhat extreme they illustrate that we have to look beyond the individual body condition scores of cows at one point during the production year to get the most of body condition scoring.

A quick reference guide to body condition scoring may be accessed and downloaded at https://www.bookstore.ksre.ksu.edu/pubs/MF3230.pdf

For more information contact Justin Waggoner at jwaggon@ksu.edu .

“The Basics of Mineral Nutrition”

By Justin Waggoner, Ph.D., Beef Systems Specialist

Most beef cattle producers recognize that mineral nutrition is important. However, a mineral program is only one component of an operation’s nutrition and management plan. An exceptional mineral program will not compensate for deficiencies in energy, protein or management. Additionally, the classical signs associated with clinical deficiency of a particular mineral (wasting, hair loss, discoloration of hair coat, diarrhea, bone abnormalities etc.) are not often or are rarely observed in production settings. The production and economic losses attributed to mineral nutrition in many situations are the result of sub-clinical deficiencies, toxicities and antagonisms between minerals which are often less obvious (reduced immune function, vaccine response, and sub-optimal fertility). The figure below, adapted from Wikse (1992), illustrates the effect of trace mineral deficiency on health and performance and the margin between adequate mineral status and clinical deficiency.

Many producers erroneously assume that the science of mineral nutrition is relatively complete. However, mineral nutrition is complicated and our knowledge of mineral nutrition is actually relatively incomplete. There are 17 minerals required in the diets of beef cattle. However, no requirements have been established for several minerals that are considered essential (Chlorine, Chromium, Molybdenum, and Nickel). Minerals may be broken down into two categories. 1. The macrominerals whose requirements are expressed as a percent of the total diet (calcium, phosphorous, magnesium, potassium, sodium, chlorine and sulfur). 2. The microminerals or trace minerals (required in trace amounts) whose requirements are expressed as parts per million (ppm) or milligrams per kilogram of dry matter consumed (chromium, cobalt, copper, iodine, iron, manganese, molybdenum, nickel, selenium and zinc).

Mineral status of an animal is a function of the total diet (both water and feed) and stored mineral reserves within the body. Water may be a substantial source of mineral; however the variation in water consumption, makes estimating the contribution of mineral from water sources difficult. Mineral content of forages is influenced by several factors including plant species, soil, maturity, and growing conditions. These factors, and others not mentioned, makes estimating the dietary mineral content of grazing cattle challenging. Most commercial mineral supplements are formulated to meet or exceed the requirements for a given stage of production. This ensures that deficiencies are unlikely, but providing supra-optimal levels of minerals may be unnecessary unless specific production problems exist. A mineral program does not have to be complex or expensive to be successful. Minerals are an important component of beef cattle nutrition that should not be over-looked as sub-clinical deficiencies of minerals likely contribute to more production and economic losses than we realize. For more information, contact Justin Waggoner at jwaggon@ksu.edu.