Beef Cattle Browsing – July 2005


Beef Cattle Browsing

Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus

July 2005

This newsletter is published by Texas AgriLife Extension – Animal Science. Media, feel free to use this information as needed and cite Texas A&M University Beef Cattle Browsing Newsletter, Dr. Steve Hammack.

NATIONAL ID: WHEN & WHY?
At this point, the USDA has proposed that “stakeholders identify premises and animals according to NAIS standards by January 2008 and that full recording of defined animal movements be required by January 2009″. (http://animalid.aphis.usda.gov) That deals with health considerations. Is that the only reason for ID? Maybe not. If we ever get the Japan market back, at this point it will be restricted to animals no older than 20 months. How will that be determined? Carcasses with USDA A40 maturity will qualify, but a rather small percentage of cattle meet that requirement. Otherwise, documented age will be required. That’s where ID could apply or cattle would not be eligible for this market, and maybe for other value-added, source-verified markets. Those and other subjects involving ID will be featured at this year’s 51st Annual Texas A&M Beef Cattle Short Course (August 1-3, 2005). If you’re accessing this on the Texas A&M Department of Animal Science website, just look on the home page for information on the Short Course. Or you can access the website at https://animalscience.tamu.edu/ There you can also find a recent publication, “The National Animal Identification System: Frequently Asked Questions About Premises ID” (ASWeb-119), located under “Publications/Beef Cattle”.

NITRATES AND PRUSSIC ACID
Dry weather is upon us, increasing the chance for nitrates and prussic acid in forages, especially sorghums, sudans, johnsongrass, etc. Though similar in some ways, these two compounds have some important differences. Under drouth conditions, nitrates may be highly concentrated in the water that plants take up, plants discontinue growth, and nitrates accumulate. Animals may not be able to convert all the excess nitrate to protein, nitrite levels build up, and animals die from lack of oxygen. Prussic acid can accumulate to dangerous levels due to poor growing conditions, stunted growth after grazing or hay harvest, new growth after prolonged drouth, or plant injury such as by frost. As with nitrates, animals can die from lack of oxygen. Nitrates do not dissipate in cured hay, but prussic acid does. Forages can be sampled and analyzed for both problems. For more information on sampling, analyzing, managing, and treating for these conditions, see Texas Cooperative Extension Bulletin L-5433, “Nitrates and Prussic Acid in Forages”, http://tcebookstore.org/tmppdfs/6680062 L5433.pdf

GENETICS OF REPRODUCTION
Brazilian researchers studied genetic relationships between age at first calving (AFC), first calving date (FCD, number of days between start of first breeding and conception), lifetime average calving date (ACD), scrotal circumference (SC), and 550-day weight (WT) in over 53,000 calving records of Nelore cattle, a Bos indicus breed dominant in Brazil. As has been found in numerous other reports, heritability estimates for female reproductive traits were low, averaging 0.07 for AFC, 0.10 for FCD, and 0.05 for ACD. Heritabilities averaged 0.43 for SC and 0.30 for WT. Genetic correlations were low between FCD and SC (-0.14) and between ACD and SC (-0.10). Genetic correlation was high between AFC and FCD (0.94) and between AFC and ACD (0.76). There was little genetic relationship between WT and either FCD or ACD. These results indicate favorable genetic relationships between various female reproductive traits that might be useful in selection programs. However, as has been seen in some other studies, SC would not be very effective in predicting reproductive traits in female relatives. (J. Animal Sci. 83::1511)

EFFECTS OF EARLY WEANING ON FIRST-CALF HEIFERS

With the prospects for continued dry weather, producers may be thinking about various ways to cope. Weaning calves early could be one of those ways. Florida researchers used two-year-old first-calf Brahman heifers to study some effects of early weaning. Heifers averaged weighing 779 lb, 3.7 Body Condition Score, and age of their calves was 93 days. At that time, half of the calves stayed on the dam (NW) and half were weaned (EW). During the next 10 weeks, cattle were kept in drylot on chopped stargrass hay and supplement to achieve targeted weight gains of 1.25 lb/day. NW cows actually gained 1.12 lb/day and EW gained 1.45 lb/day. At the end of the 10 weeks, BCS of NW cows was 4.9 and EW was 5.0. However, the NW cows and calves consumed 59% more TDN than EW cows. And only 33% of NW cows had cycled, compared to EW cows at 83%, all of which cycled by two weeks after calves were weaned. Early weaning, especially with young, thin cows, can reduce nutritional cost and improve reproductive performance. Early-weaned calves must be provided nutrition from other sources or sold at weights lighter than usual. However, it may be worth it to save cow feed expense and keep the herd on the same calving schedule. (Prof. Anim. Sci. 20:34)

FACTORS AFFECTING COW-CALF PROFIT
The North Dakota Farm Business Management Program Livestock Enterprise Analysis for 2004 separated herds into the High 20% and Low 20%, based on net return. High averaged $262 and Low $78 net return. Weaning weight averaged 31 lb heavier for High, or about $40/hd at today’s prices. Calves from High herds brought an average of $7.70/cwt more than Low, also about $40/hd. In these data, weaning percentage for High was only 0.9% greater than Low, which would amount to only about $6/hd. Standardized Performance Analysis data, covering several years, reported by the Texas A&M Department of Agricultural Economics has showed roughly equal effects from weight, price, and weaning percent for high- versus low-profit herds. However, as with SPA data, the biggest factor in profit was cost of production. Low herds had $81 more total expense than High herds. (Summarized from data tabled in the Summer, 2005, Michigan State University Beef Cattle Research Update, An. Sci. Staff Paper 513)

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