How Many Heifers to Keep?

Transcription

1 January 2010 How Many Heifers to Keep? Bob LeValley From the Cow/Calf Corner Archives During the winter months as producers reflect on decisions made during the previous year to plan for the future, one of the items for thought is the proper number of cows for the operation. Matching the number of cattle to the grass and feed resources on the ranch is a constant challenge for any cow-calf producer. Also producers strive to maintain cow numbers to match their marketing plans for the long term changes in the cattle cycle. Therefore it is a constant struggle to evaluate the number of replacement heifers that must be developed or purchased to bring into the herd each year. As a starting place in the effort to answer this question, it is important to look at the average cow herd to understand how many cows are in each age category. Dr. Kris Ringwall, director of the Dickinson, North Dakota Research and Extension Center recently reported on the average number of cows in their research herd by age group for the last 20 years. The following graph depicts the average percent of cows in this herd by age group. choosing how many heifers we need to save each year. Next, we must predict the percentage of heifers that enter a breeding season that will become pregnant. The prediction is made primarily upon the nutritional growing program that the heifers receive between weaning and breeding. Researchers many years ago, found that only half (50%) of heifers that reached 55% of their eventual mature weight were cycling by the time they entered their first breeding season. If these heifers were exposed to a bull for a limited number of days (45-70), not all would have a chance to become pregnant during that breeding season. Therefore, it would be necessary to keep an additional 50% more heifers just to make certain that enough bred heifers were available to go into the herd. For instance, if you needed 17 bred heifers to enter the herd, you would want to expose at least heifers to the bull. Those heifers that did not conceive during the short breeding season would be immediately identified by preg checking and then sold as stocker heifers. However if the heifers were grown at a more rapid rate and weighed 65% of their eventual mature weight, then 90% of them would be cycling at the start of the breeding season and a much higher pregnancy rate would be the result. Under this nutritional regime, we would expose only 20 or 21 heifers in order to assure 17 were bred. The above graph indicates that the typical herd will, on the average, introduce 17% new first calf heifers each year. Stated another way, if 100 cows are expected to produce a calf each year, 17 of them will be having their first calf. Therefore this gives us a starting point in Even in the very best scenarios, some heifers will be difficult or impossible to breed. Most extension specialists and researchers write about the need to always expose at least 10% more heifers than you need even when they are grown properly and all weigh at least 65% of the expected mature weight. Always cull open heifers after their initial breeding season. This is the easiest opportunity they will have to become pregnant. If they fail as heifers, they will be a bad bet to keep around and try to breed in subsequent years.

2 Supplementation Priorities for Cows Grazing Dormant Winter Pastures Bob LeValley When supplementing cows grazing low quality dormant grass this winter, priority should first be placed on meeting the protein requirement in order to maximize forage intake and digestion. Many years of research have consistently shown that protein supplementation for cattle grazing protein-deficient forage is the highest nutritional priority. In fact, energy supplementation will not be effective if dietary protein is deficient. Once the producer ensures that the supplementation (or feeding) program will meet the protein requirement, energy (TDN) intake should be evaluated, based on the requirements of the cow for the current stage of production. The decision must be made whether the cattle need to maintain body weight and condition, gain weight and condition, or whether they can be allowed to lose some weight and condition. This decision will dictate how much supplemental energy should be provided. See OSU Fact Sheet, ANSI-3283, Body Condition Scoring of Beef Cows for information on body condition scoring cows and how body condition scores influence reproductive performance. The third priority, vitamin and mineral requirements, should be compared to expected intake, potential deficiencies identified, and supplemental feed alternatives evaluated. This is not to say that vitamins and minerals are not important. Priority is given to protein and energy nutrition first because these items are needed in much greater quantities and they have the potential to have much greater impact on animal performance and efficiency of forage utilization. Vitamin and mineral nutrition of grazing cattle is discussed in detail in OSU Extension publication E

3 Why Do Alfalfa Fields Continually Test Deficient In Phoshorus? This question is often asked by alfalfa producers who fertilize their fields according to a soil test each year and do not see any improvement in their soil test P value. The easiest way to answer this question is to consider the soil as a "black box" and that in order for the level in the black box to raise, more has to be put in each year than what is taken out. We know that good quality alfalfa removes about 14 lb of P (expressed as P 2 O 5 )/ton of hay. So, a field that produces 5 ton/acre/year could remove about 70 lb of P 2 O 5 /acre each year. If the soil test P index for this field before it was planted was 30 (OSU soil test), the soil test calibration would identify a deficiency of 80 lb P 2 O 5 /acre. Applying 80 lb P 2 O 5 /acre each year would about equal the P removed each year if 5- ton yields were maintained. Mark S. Gregory From: alfalfa.okstate.edu If the soil test is a measure of the level of P that will become available to the crop during the growing season, then we should expect the soil test to remain about the same each year and for it to continue to show a P deficiency and the need to keep applying about 80 lb P 2 O 5 /acre. Although the uptake of P by alfalfa, reactions of fertilizer P with the soil, and the dynamics of soil P are quite complex, the "black box" approach provides a fairly true explanation for what happens to the soil test P value when the deficiency amount identified by the soil test is close to the amount of P removed by the crop. We cannot always take this approach, and in fact do not recommend as a "general rule" adding back the amount of P that is removed in harvests each year. No Phosphorus added Applied Phosphorous 3

4 How to Avoid Paying Back Your 2009 FSA and NRCS Program Payments: AGI Payment Eligibility Daniel Skipper The Food, Conservation, and Energy Act of 2008, more commonly known as the 2008 Farm Bill, set average adjusted gross income (AGI) limits on eligibility for program payments. In general, the limitations are: $500,000 average nonfarm AGI for commodity programs; $750,000 average farm AGI for direct payments under the Direct and Counter-Cyclical Program or ACRE program; and $1 million average nonfarm AGI for conservation programs. In order to verify that these limits have not been exceeded, USDA and IRS have created a datasharing program that will ensure that FSA and NRCS program participants are in compliance with AGI limitations. The program looks at certain line items on tax returns and calculates an AGI for the last three years. This calculation is compared to the AGI limitations and the results are sent to the USDA, who which will only share the results with FSA and NRCS. No actual tax data will be included in the report and no USDA county office personnel will be able to view tax return information at any time during the process. The report will only signify whether an individual or entity meets or does not meet AGI criteria for specific programs. In order to begin this verification process, individuals or legal entities must provide the IRS with written consent. This consent can be granted using Form CCC-927, Consent to Disclosure of Tax Information Individual or Form CCC-928, Consent of Disclosure of Tax Information Legal Entity. These forms can be completed for years 2009, 2010, or both years. The consent forms should be mailed directly to IRS at the address given on the form no later than June 15, This form should not be returned to either the FSA or NRCS offices. While the deadline is not until June 15 th, the earlier the forms are completed and returned, the less likely you will incur delays in your 2010 program payments and the possibility of being asked to refund USDA for your 2009 program payments. Those that chose not to submit the completed forms or forget to return the form by the deadline will be determined noncompliant with AGI limitations for the 2009 and 2010 crop and program payments and will be asked to refund USDA for any payments already received for those years. Please contact your local FSA and NRCS office to receive more information. 4

5 Start Now to Avoid Calf Scours Next Spring Gene Parker Jr. DVM OSU Extension Food Animal Health Specialist Calf Scours, or neonatal calf diarrhea, is a problem experienced by most every cowman sooner or later. It is quite possibly the biggest health related financial loss to the cow calf industry. It is easy to recognize the impact that dead calves and increased cost of medical treatment has on the bottom line, but poor performance is an even greater though less noticeable loss. A Colorado study shows that calves that experienced calf scours and recovered had a 23 pound lower average weaning weight than their herd mates who did not experience difficulty. Other studies have shown that the loss of performance carries through the stocker and feedlot phases of production. When scours hits a herd at calving time it is too late to avoid the financial setback. Prevention consists of an all-year management plan to enable newborns to deal with the challenge when they have to face it. It is important to understand that calf scours is not a specific disease, but a clinical sign that can be caused by many different infectious agents and several predisposing factors. Scours results in dehydration, often severe and nonreversible, due to the failure of absorption of water and electrolytes from the gut and increased secretion of water into the gut. The bacterium E. coli causes scours during the first few days of life, while Roto virus, Corona virus and Cryptosporidium cause problems between 7 and 21 days of age. Other organisms can cause infections also but the mechanism is about the same no matter what agent or agents are involved. Three things determine the eruption of clinical disease: 1) Exposure rate or the number of organisms impacting the calf, 2) calf immunity levels, and 3) stress on the calf. These are all variables that can be influenced by management. Disease will occur any time the exposure rate exceeds the calf s immunity level. Exposure rate is basically a summary of each herd s sanitation conditions. Too often we actually kill em with kindness when we bring cows into confinement or small calving pastures to calve. The cleaner the area where the calf is born, the less exposure there will be. Calves are exposed with organisms primarily by fecal oral transfer but in the case of E. coli, exposure can also be through the navel at birth. Since the organisms live for several months in the guts of calves that survive a slight infection, older calves play a role by passing the organisms to their younger siblings. Move older calves and their dams to other areas and do not allow calves of various ages to share the same environment. Calf immunity is from passive transfer of antibodies from the dam. Since calves are unable to receive antibodies in the uterus, they must rely solely on colostrum and they need to receive sufficient quantities in the first few hours of life. Figure 1: shows how the calf s ability to absorb these complex immunoglobulins starts to decrease soon after birth. 5

6 Figure 2: shows the comparative immunity levels that are present in calves that receive slight, moderate, or adequate amounts of colostrum from their dams. Figure 3 Effect Of The Dam's Udder Structure On Time To First Suckling By Calves Height of teats Time to first suckling (hours) Percentage of calves not suckling within 6 hours of birth More than 3 inches above hock level At hock level More than 3 inches below hock level Source: United Kingdom National Agricultural Center Calif Unit, as quoted by S. Brooke in Hoard's Dairymen Figure 3: shows the delay in first nursing when cows have pendulous udders, and as we have seen above, time to first nursing is of the essence. Culling cows with bad bags is a management tool that can go a long way towards preventing calf scour cases. Not only are their calves more at risk, but more affected calves means more calves shedding organisms that contribute to the exposure rate and affect all of their siblings. In herds with a history of problems cow vaccination programs may be helpful by elevating the amount of immunity transferred in colostrum. Cows should be vaccinated with a scour vaccine product 6 to 8 weeks before calving and then given a booster 3 weeks prior to calving. In cows that have previously received scour vaccine, the circulating antibody level and thus the colostrum antibody levels reaches it s maximum elevation about 3 weeks after vaccination. Antibody 6 preparations are available for oral administration to newborn calves but they are expensive and of questionable value in that they do not offer protection against all possible causative organisms. The third consideration is stress. Anything that stresses the calf increases the likelihood of scours by decreasing the tissue s ability to resist invasion. Stress factors can be classified as nutritional, environmental, or social. Poor cow nutrition results in poor milking and subsequently nutritional stress in the calf due to low energy level and metabolic rate. Nutritional deficiency in the dam, especially mineral or protein deficiency, also results in problems by depressing their immunity and the immunity they pass to the calf. Newborn calves are stressed

7 more by inclement weather than older animals because for the first hours of life they cannot regulate their body temperature effectively. Colostrum deprivation is a triple threat because colostrum not only provides the total available immunity but also provides easily absorbed nutrients and helps to warm the newborn. Social stress is often due to overcrowding, which also raises the exposure rate, or separation of the newborn from his mother. Treatment of scours consists of rehydrating the calf with electrolyte solution and treating with antibiotics to prevent the infection in the gut from entering the bloodstream. It is important to use a drug that is labeled for calf scours to ensure that it is effective in the gut and to prevent liability due to drug residues. Calves that have loose stools but are zipping around the pasture with their tails up do not need treatment. The decision to treat should be based on the degree of depression, loss of appetite, dehydration and elevated body temperature. Perhaps the most important decision is determining when to seek help. If over 5% of the calves are needing treatment, or death loss due to scours is running over 2%, it is time to get help from your veterinarian. Like many health challenges, calf scours is better prevented with a comprehensive management program than treated. Treatment may help with recovery of individual cases but it is a lot like shutting the gate after the cows are out when it comes to avoiding economic losses. Oklahoma State University, U.S. Department of Agriculture, State and Local governments cooperating. In compliance with Title VI and VII of the Civil Rights Act of Executive Order as amended. Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal and state laws and regulations, does not discriminate on the basis of race, color, national origin, sex, age, religion, disability, 7 or status as a veteran in any of its policies, practices or procedures.