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Previous issues of the BEEF Cattle letter

Issue # 539

May 30, 2007

Forage Focus: Summer Water Requirements for Cattle - Rory Lewandowski, Extension Educator, Ag/NR Athens County

As I write this article in May, we are already experiencing temperatures in the upper 80's combined with scare rainfall. There are creeks dry in May that haven't been dry in May in a long time. It may turn out to be a hot, dry summer. Water may become an issue in some pasture situations. While we often talk a lot about nutrition, forage quality, and mineral needs, water is sometimes taken for granted, almost overlooked. Yet water is the most essential nutrient for livestock production. Cattle can survive for a number of days, even up to weeks without food, but will die within a few days without water. Assuming that the goal of most cattle producers is more than just cattle survival, it is important that cattle receive a sufficient quantity of water each day to maximize feed intake, produce milk for the calf, and maintain a healthy reproductive cycle.

Research has shown that without a sufficient quantity of water, dry matter intake of cattle is reduced. This reduction in dry matter intake affects production, whether that is gain, growth, lactation or reproduction. The quantity of water needed by cattle is influenced by air temperature, activity level of the animal, lactation, and type of feed. As air temperature, activity level and lactation level increase so does the requirement for water. A ration low in moisture, compared to a pasture ration of young vegetative grass will require more water. The following chart provides an estimate of the gallons of water needed per day for various classes of beef cattle under varying summer temperatures:

Daily water intake (Gallons)1

1. Compiled from 1996 NRC Requirements for Beef Cattle and Winchester and Morris, 1956. Water Intake Rates of cattle. Journal of Animal Science, 15:722.

Recognize that these figures are estimates. They take into account air temperature, and, to some degree, the production level of the animal, but activity level, humidity and, for pastured animals, moisture content of the pasture can all affect these numbers. I have seen tables that put the requirement for a lactating beef cow in 90-degree heat at 25 plus gallons of water per day. Still, the chart provides a starting point for the cattle producer to determine the water needs of his/her animals.

How this quantity of water will be delivered to the herd is an important consideration. Smaller paddock sizes with a water source in each paddock is the ideal because it minimizes animal energy expended walking to a water source and allows animals to come to the water source on an individual basis. In practical terms this means that the water system can be designed with lower flow rates and smaller water tanks. As a guideline, provide a tank that allows two to four percent of the animals to drink at one time and a flow rate that provides the total daily need in four hours. Larger paddocks, where a trip to the water source involves traveling out of sight of herd mates, generally means cattle will come to water as a herd. The result is that the water system must be designed to provide a larger quantity of water within a shorter time frame. The rule of thumb for this situation is to provide enough tank space for 10 percent of the cattle to drink at one time and a flow rate adequate to insure that all the cattle can drink in about 20 minutes.

While the quantity of water supplied is critical, the quality of that water is an important consideration as well. Poor and/or contaminated water supplies decrease cattle consumption of water, which affects dry matter intake and decreases animal performance. Additionally, certain contaminants can directly impact upon the health of cattle, and, in extreme cases, result in death. Water quality for livestock can be evaluated in terms of salt concentration, nitrate levels, sulfates and sediment. Salt concentration is determined by the amount of dissolved inorganic salts such as calcium chloride, sodium chloride, magnesium chloride, sulfates and bicarbonates contained in the water. Generally a level of 3000 milligrams per liter (mg/l) or parts per million (ppm) or lower is the limit for a cattle water source. The nitrate level in water should be under 300 mg/l or 300 ppm. Sulfates in the water source are a concern because sulfur can tie up dietary copper, zinc and manganese. A general recommendation is that water sulfate concentrations not exceed 1000 mg/l or ppm. There are a number of labs around the state that can do a water quality analysis for livestock.

As a side note, any producer feeding supplemental grains or by-product feeds should be aware of the sulfur concentration of those feeds plus what the water source may contain. High sulfur levels in the total ration can lead to reduced gain, and, in extreme cases, result in sulfur induced polioencephalomalacia (PEM), a central nervous system disease that causes cattle fatality.

As we enter the summer months producers need to insure that their cattle will have an adequate supply of clean, fresh water to maintain cattle health and performance.

References:

Beef Cattle Water Quality. Dan Grooms DVM, Ph.D, Veterinary Extension, Michigan State University

The Cow-Calf Manager Livestock Update. March 2002. John Hall, Beef Specialist Virginia Tech

Sulfur-induced Polioencephalomalacia in a Herd of Rotationally Grazed Beef Cattle. Canadian Veterinary Journal, October 2003.

Watering Systems for Grazing Livestock. Publication of Great Lakes Basin Grazing Network and Michigan State University Extension

Tips For Better Manure Application In Alfalfa - Bruce Anderson, University of Nebraska-Lincoln Extension Forage Specialist

If you have manure to spread this summer, sometimes the only place available is an alfalfa field. Be aware, however, that manure can cause problems on alfalfa.

Liquid manure can burn leaves due to salt injury, and dry manure can smother plants if it is applied too heavily or in large chunks. Manure can spread weed seeds, and the nitrogen in manure can stimulate grasses already in the alfalfa to become more competitive. Also, manure application equipment can damage alfalfa crowns and compact soil.

When possible, spread manure on other land, but, if you have no other choice, follow these suggestions:

* Apply less than three thousand gallons of liquid manure or ten tons of solid manure per acre to minimize salt burn or smothering. If manure is dry, adjust the spreader to break up large chunks that can smother growth.

* Spread manure immediately after removing a cutting to minimize direct contact with foliage.

* Only spread manure when fields are dry and firm to limit soil compaction and avoid wheel traffic damaging plant crowns.

* If you wish to stimulate grass yield, apply manure to fields with lots of grass; otherwise, select fields with little grass if you want to minimize grass competition.

Manure is an excellent source of nutrients and can enhance biological activity and soil physical properties, but be careful when applying it to alfalfa so you don't do more harm than good.

"Preg" Check and Cull Replacement Heifers Early - Dr. Glenn Selk, Extension Cattle Specialist, Oklahoma State University

Many Oklahoma ranchers choose to breed the replacement heifers about a month ahead of the mature cows in the herd. In addition, they like to use a shortened 45 to 60-day breeding season for the replacement heifers. The next logical step is to determine which of these heifers failed to conceive in their first breeding season. This is more important today than ever before.

As the bulls are being removed from the replacement heifers, this would be an ideal time to call and make arrangements with your local veterinarian to have those heifers evaluated for pregnancy in about 60 days. In two months, experienced palpaters should have no difficulty identifying which heifers are pregnant and which heifers are not pregnant (open). Those heifers that are determined to be "open" after this breeding season, should be strong candidates for culling. Culling these heifers immediately after pregnancy checking serves three very economically valuable purposes.

1) Identifying and culling open heifers early will remove sub-fertile females from the herd. Lifetime cow studies from Montana indicated that properly developed heifers that were exposed to fertile bulls, but DID NOT become pregnant were often sub-fertile compared to the heifers that did conceive. In fact, when the heifers that failed to breed in the first breeding season were followed throughout their lifetimes, they averaged a 55% yearly calf crop. Despite the fact that reproduction is not a highly heritable trait, it also makes sense to remove this genetic material from the herd so as to not proliferate females that are difficult to get bred.

2) Culling open heifers early will reduce summer forage and winter costs. If the rancher waits until next spring to find out which heifers do not calve, the pasture use and winter feed expense will still be lost and there will be no calf to help eventually help pay the bills. This is money that can better be spent in properly feeding cows that are pregnant and will be producing a salable product the following fall.

3) Identifying the open heifers shortly after (60 days) the breeding season is over will allow for marketing the heifers while still young enough to go to a feedlot and be fed for the choice beef market. The grading change of several years ago has a great impact on the merchandising of culled replacement heifers. "B" maturity carcasses (those estimated to be 30 months of age or older) are very unlikely to be graded Choice and cannot be graded Select. As a result, the heifers that are close to two years of age will suffer a price discount. Currently non-pregnant, yearling 875 pound heifers (shortly after a breeding season) are selling for about $94 per cwt. Therefore an 875 pound, culled replacement heifer is worth about $822. Non-pregnant two-year old cows are selling for about $65 to $70 per cwt. Open two-year old cows (those that could have been identified shortly after the breeding season) that weigh 1000 pounds would only sell for about $700 next spring.

The average expense for owning the cow is about $1 per day. So the total loss of keeping the open heifer would be about $200 in feed and forage and another $122 in lost value. The grand total expense for not culling open replacement heifers in today's market is about $322 per head. Therefore, it is imperative to send heifers to the feedlot while they are young enough to be fed for 4 to 5 months and not be near the "B" maturity age group.

Certainly the percentage of open heifers will vary from ranch to ranch. Do not be concerned, if after a good heifer development program and adequate breeding season, that you find that 10% of the heifers still are not bred. These are the very heifers that you want to identify early and remove from the herd. It just makes good economic business sense to identify and cull non-pregnant replacement heifers as soon as possible.

Factors Affecting Conception Rate - Rory Lewandowski, Extension Educator, Ag/NR Athens County

Why do some cows breed back more successfully than other cows in the same herd? Why do herd conception rates vary from year to year? Body condition and nutrition can offer some explanation. Research has demonstrated that cows in poor body condition and/or under nutrient stress will have lower conception rates and take longer to rebreed compared to cows in good body condition and provided with a ration meeting nutrient requirements. But, are there other factors that can affect re-breeding and conception rates? I want to summarize a presentation from Dr. James K. West, DVM and director of the embryo transfer unit veterinary service at Iowa State University, in which he lists both non-infectious and infectious causes for reduced conception rates in beef herd.

Some non-infectious factors that can reduce conception rates include: lethal genes, polyspermy, endocrine disorders, elevated blood urea nitrogen, heat stress and handling/transportation stress. Lethal genes and polyspermy (fertilization of the egg with more than one sperm, which is a lethal condition) both refer to genetic factors that do not allow a viable pregnancy to occur. Endocrine disorders result in short or irregular heat cycles or a condition where not enough progesterone is produced to sustain a pregnancy. With these 3 factors the producer has little control and culling is probably the best option for the producer.

Elevated blood urea nitrogen, heat stress and handling/transportation stress are other factors that can cause reduced conception rates. Producers may be able to minimize the detrimental effects of these factors through management practices. Elevated blood urea nitrogen can occur on lush pastures and is related to crude protein consumption. Crude protein content of pasture grass can be increased through nitrogen fertilization. High crude protein levels in the diet increase the blood urea nitrogen content which can bring about alterations in uterine secretions and a decrease in uterine pH that results in lower conception rates. Avoid nitrogen fertilization of pastures immediately before grazing lush pastures during the breeding season. Heat stress occurs when there are prolonged periods of temperatures over 90 degrees F combined with humidity of 40% or greater. Breeding during these conditions can result in early embryonic death, especially in the first 6 days after egg fertilization. Finally, reducing handling stress can be accomplished by working cattle in the cool part of the day, providing working facilities that are efficient, and working cattle in a calm and un-hurried manner.

Infectious diseases that cause reproductive problems include: Infectious Bovine Rhinotrachetis (IBR), Leptospirosis, and Bovine Viral Diarrhea (BVD). It is beyond the scope of this article to go into details about each of these diseases, but each can cause reduced conception rates, and, in many instances, abortions. Vaccines are available, often in combinations to provide protection against these diseases. Unfortunately, in the case of Leptospirosis and BVD, vaccines are not always effective.

High conception rates and full-term pregnancies are necessary to maintain a profitable beef herd. By recognizing non-infectious and infectious factors that can reduce conception rates and pregnancy, producers can adopt management practices that will provide cows the best opportunity for successful re-breeding.

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BEEF Cattle is a weekly publication of Ohio State University Extension in Fairfield County and the OSU Beef Team. Contributors include members of the Beef Team and other beef cattle specialists and economists from across the U.S.

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