K-State Research and Extension

“Protein Sources for Growing Cattle”

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

One of the outcomes of the recent Coronavirus (COVID-19) situation that unexpectedly affected many cattle feeding operations throughout Kansas and the Midwest was a sudden reduction in the availability of distiller’s grains. As many Americans heeded “stay at home” orders, demand for fuel, oil, and ultimately ethanol fell resulting in price declines that forced many ethanol plants to scale back production. The cattle feeding industry has relied heavily on distiller’s grains as the primary source of protein in both growing and finishing rations for many years. Distiller’s grains comprise 10-30% of many cattle rations depending upon the nutrient composition and price of other commodities. The reduced supply of distiller’s grains forced many cattle producers to look at traditional sources of protein, such as soybean meal, cottonseed meal, alfalfa and urea that many producers had not used for at least a decade. The prices of several common commodity protein sources (central, KS; obtained 4/28/2020) on a per ton and a cost per unit of protein basis are shown below. It is essential that producers evaluate protein sources on a cost per unit of protein prior to making purchasing decision. All of the traditional protein sources in the table were comparably priced on a cost per unit of protein basis ($0.44-0.49 /lb CP) with the exception of urea. However, urea must be used with caution, should not comprise more than 0.5 to 1.0% of the total diet on a dry matter basis, and it is generally recommended that urea be added into the ration using a premix or liquid to ensure that urea is appropriately mixed in the 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 do not 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 overconditioned 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.

“Cow Nutrition: Protein, Energy and Forage Availability”

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

Protein supplementation is important, but there is more to cow nutrition than simply ensuring that the cow’s protein requirements are met and that we have supplied the rumen microbes with sufficient nitrogen to digest the low-quality forages that sustain our cows through the winter months. Most cattle producers know and appreciate the value of protein supplementation, but often overlook energy. Although, protein supplementation does impact energy status by enhancing digestibility and intake of low-quality forages.

The benefits of protein supplementation are not fully realized by the cow if forage availability (supply) is limited. Both protein and energy requirements steadily increase during gestation and post-calving. Thus, there are many production scenarios, where both protein and energy may become limiting or where energy becomes more limiting than protein, minerals or vitamins.

I have found that producers often attribute negative production outcomes, such as higher percentage of open cows, with their previous protein supplementation protocols or mineral and vitamin deficiencies. Protein, minerals and vitamins are important components of cow nutrition, but in many cases energy deficiency may be the more likely cause. Energy status of grazing beef cows is essentially a function of forage availability in most situations.

The most basic way to think about forage availability is to ask yourself “Does each cow have all she can eat in the pasture or field?” If the answer to that question is “No” then energy is likely the most limiting factor in your production system. There are many ways to address situations where energy has become limiting. Feeding hay to replace grazed forage, moving to a new pasture or field of stalks or feeding combination supplements that provide both protein and energy are all strategies that may used to increase energy status.

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

“Supplementing Cows During Cold Weather”

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

The New Year often brings with it some of the coldest months of the year. Most cattle producers know and appreciate that cold weather increases nutrient requirements. However, the real question is what should producers feed or supplement when the wind blows and the mercury barely registers on the thermometer.

Cattle are most comfortable within the thermoneutral zone when temperatures are neither too warm nor cold. During the winter months, cattle experience cold stress anytime the effective ambient temperature, which takes into account wind chill, humidity, etc., drops below the lower critical temperature. The lower critical temperature is influenced by both environmental and animal factors including hair coat and tissue insulation (body condition). The table below lists the estimated lower critical temperatures of cattle in good body condition with different hair coats. In wet conditions, cattle can begin experiencing cold stress at 59°F, which would be a relatively mild winter day. However, if cattle have time to develop a sufficient winter coat, the estimated lower critical temperature under dry conditions is 18°F.

Cold stress increases maintenance energy requirements but does not impact protein, mineral or vitamin requirements. The general rule of thumb (for a cow in good body condition, BCS = 5 or greater) is to increase the energy density of the ration by 1% for each degree (Fahrenheit) below the lower critical temperature. The classic response to cold stress in confinement situations is an increase in voluntary intake. However, it has been documented that grazing beef cows may spend less time grazing as temperatures decline below freezing, which reduces forage intake, and makes the challenge of meeting the cow’s nutrient requirements even greater. In many cases, feeding a greater amount of low-quality hay will replace grazed forages but may not provide sufficient energy. Therefore, providing additional energy by feeding a relatively higher-quality hay or fiber-based supplement (DDGS, Corn gluten feed, or Soybean Hulls) may be required. If fiber-based energy sources are not available, small amounts (2-3 lbs) starch-based concentrates may also be used as energy supplements.

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