Beef Cattle Browsing
Editor: Dr. Stephen Hammack, Professor & Extension Beef Cattle Specialist Emeritus
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.
GENETIC SELECTION FOR OVULATION
The U. S. Meat Animal Research Center since 1976 has been studying twinning, starting with a group of 96 females that had produced twins at least twice. That population now has a twinning rate of 50%. Early in the studies, it became apparent that ovulation rate was an effective predictor of twinning. Twinning can occur bilaterally (one corpus luteum, CL, from each ovary) or unilaterally (both CL from the same ovary). Bilateral twinning, compared to unilateral, decreased calving difficulty by 14% and increased calf survival by 10%. Over the course of this work, ovulation rate has steadily increased and has been greater in the right ovary, as other studies have shown. Ovulation rate now averages 1.48 CL per ovulation, and has been shown to increase with age. Based on their work, MARC researchers concluded that selection for ovulation rate can be increased by genetic selection, and that selection for bilateral ovulation also may be possible. However, they caution that the generally detrimental effects of triple and quadruple ovulations also may also increase. (J. Animal Sci. 83:1839)
HOW MANY CAN YOU HAUL?
According to Kansas State’s Beef Stocker USA, in a 77-inch-wide truck you can haul 169 200-pounders, 54 800-pounders, or 31 1400-pounders. This and other useful information on cattle transportation can be found at http://beefstockerusa.org/transportationfact.htm
VITAMIN E FOR NEWLY-RECEIVED CALVES
Oklahoma researchers used 715 calves (79% heifers, 21% steers and bulls) to study the effects of Vitamin E supplementation during a 42-day receiving period. Calves were purchased in seven groups from auctions in southern Oklahoma and northern Texas. The average received weight of the groups ranged from 332 lb to 515 lb. Calves were fed 2000 IU Vitamin E/hd/day for 0, 7,14, or 28 days. There was no significant effect on gain or feed efficiency. Incidence of respiratory disease overall was high, averaging 64.6%. There was a statistically non-significant trend for sickness, number of medical treatments, and medical cost to decrease as length of Vitamin E supplementation increased (for 0 vs 28-day supplementation: morbidity was 67.8% vs 60.3%; treatments/calf was 0.92 vs 0.76; medical cost was $6.29 vs $4.88.) There was no effect on any carcass characteristic due to treatment. (J. Animal Sci. 83:1924)
EFFECTS OF POSTPARTUM MATERNAL BEHAVIOR
Arkansas researchers studied the behavior of cows just after birth. Represented were registered Angus, Charolais, Hereford, Polled Hereford, and Red Poll cows, with over 5000 births by 142 sires over 25 years. Cows were classified as either very aggressive, very attentive, indifferent, or apathetic toward handlers while tattooing and recording calf body condition score and birth weight. Angus cows were most aggressive followed by Charolais, Polled Hereford, Hereford, and Red Poll. Aggressiveness decreased as cow age increased from 3- to 10-years and decreased as body condition of calf decreased from fat to thin. Calf survivability according to cow behavior score was: very aggressive = 93%; very attentive = 86%; indifferent = 77%; apathetic = 60%. The authors speculated that higher survivability might be “caused by protection from predation or other factors that might have been involved”. (Prof. Animal Sci. 21:13)
GENETIC IMPROVEMENT OF ADAPTATION
In a paper presented at the recent Beef Improvement Federation Annual Meeting, the authors stated that, after domestication in western Asia some 10,000 years ago, cattle migrated on the average of 60 miles every 100 years. This slow movement allowed effective adaptation to new conditions. But in recent times migration has occurred at a much faster rate, and management systems have changed rapidly as well. The result is that “in many cases, management systems and environments are changing more rapidly than animal populations can adapt to such changes” and that “rapidly increased genetic potential for production may be achieved at the expense of decreased genetic merit for adaptation”. Several examples of these effects were detailed such as, in dairy, intense selection for increased milk production has been accompanied by “poor rebreeding of young cows and increased incidence of metabolic imbalances in lactating cows”. The authors state that benefits from better adaptation in beef cattle include enhanced animal well being, improved financial well being of producers, reduced cost and enhanced quality of beef, greater food security, less need to modify production environments, and better utilization and conservation of resources. The complete paper can be accessed at http://www.bifconference.com/bif2005/pdfs/Hohenboken.pdf
EFFECTS OF TRACE MINERAL SOURCE AND FEEDING METHOD
Florida researchers used 160 Braford cows over three years to study organic vs inorganic Co, Cu, Mn, and Zn, delivered either free-choice (FC, loose mineral mix in covered feeders) or control-fed (CF, 3 times/week in molasses supplement fed in open troughs). FC mineral intake was 23% less that CF, and FC cows showed lower liver levels of Cu in one year and of Zn in another year. Cow body weight, cow body condition, and calf weaning weight were not affected by mineral source or feeding method. Three- and four-year-old cows on organic minerals had higher pregnancy rates and shorter calving intervals in two of the three years. The authors concluded that organic trace minerals may improve reproductive performance in young cows, but not in mature cows. (Prof. Animal Sci. 20:155)
There is a new publication in the Texas Adapted Genetic Strategies series, “Marker Assisted Selection for Beef Improvement”, Texas Coop. Ext. E-352, by Dr. Joe Paschal, Extension Livestock Specialist located at the Texas A&M Center at Corpus Christi. To access the publication go to https://animalscience.tamu.edu , click on “Publications”, scroll down and click on “Beef Cattle”, scroll down to “Genetics and Selection”, and E-352 is at the bottom of that list.