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.
ANTHELMINTICS AND SUMMPLEMNTING HEIFERS ON RANGE
Treatment of growing cattle with anthelmintics (de-wormers) for internal parasites is often beneficial on intensively-grazed improved pasture. But what about on native range? Oklahoma State University researchers used heifers weaned in May or June to study the effects of supplementing (S) and anthelmintics (A) on heifers grazing native pasture during late summer/early fall in north central Oklahoma. There were four treatment groups: no supplement or anthelmintic (NN); supplement but no de-wormer (SN); anthelmintic but no supplement (AN); and supplement and anthelmintic (SA). The anthelmintic was Ivermectin, with clorsulon (effective against liver flukes), applied at the start of the trial on July 25 and again on August 26. Supplement was 41% CP cottonseed meal fed Mon, Wed, and Fri at 2.33 lb/feeding (averaging 1 lb/day) until October 21 (84 days).
Heifers were weighed and fecal samples collected every 28 days. The A heifers had lower fecal egg counts. Weight gain for the 84 days was: 81 lb (NN); 123 lb (SN); 106 lb (AN); and 143 lb (SA), so S and A increased gains additively, with greatest effect from S. Heifers were then commingled and grazed with minimal hay and supplement for 151 days until April 24. There was little weight change during that period, averaging (in the same order) +20 lb, -21 lb, +12 lb, and -8 lb. So, total weight gain, from start in July to end in April, was 101 lb, 102 lb, 118 lb, and 135 lb. Response during late summer/early fall from anthelmintic tended to be retained, but that from supplementing tended to be lost, during the following winter/spring. (OSU Animal Science Res. Rpt. P-1008:18)
Numerous studies, Texas A&M Ranch-to-Rail trials, and field observations have shown benefit from postweaning backgrounding on the ranch/farm for around 45 days before grazing or feeding. South Dakota State Univ. researchers studied steer calves from the same ranch. Calves (P) out of dams 4-years-old or younger were weaned one month before calves (N) out of older dams. As soon as the latter were weaned, all calves were shipped 360 miles to a feedlot, rested, then vaccinated, de-wormed, and weighed. The two groups did not differ in weight at that time. Calves were fed 21 days, during which time N gained 15 lb more and converted feed 17% more efficiently than P. There was no sickness or death in either group. At shipping, tympanic temperature sensors were placed in some steers of each group. N steers showed higher temperatures during loading and shipping, but this was not true by 10 hours after arrival. Even though fresh-weaned calves seemed to be stressed more by hauling, they quickly recovered compared to calves that had been weaned one month. However, the apparent excellent good health may have influenced results compared to some studies. (J. Animal Sci. 81:121 Suppl. 1)
GENETIC TREND: MOSTLY ONWARD AND UPWARD
The major breeds all have genetic evaluation programs reporting EPD. As part of those programs, changes over time in breed genetic averages can be followed. What has happened over the last 20 years? The trends are similar for most breeds. For example in Angus, birth weight increased 2 lb from 1984 to1992 and then stabilized through 2003. By then, weaning weight increased 26 lb, yearling weight by 52 lb, and milk (maternal effect on weaning weight) by 17 lb. In Limousin, from 1980 to 2004, birth weight increased about 2 lb by 1996 and then stabilized, weaning weight increased by 20 lb, yearling weight by 35 lb, and milk by 6 lb. Most other breeds followed similar trends, that is, stabilized birth weight and higher performance. There are a couple of exceptions. In Maine-Anjou, from 1985 to 2004, there were decreases of 2 lb birth weight, 2 lb weaning weight, 5 lb yearling weight, and 2 lb milk. In Red Poll, also from 1985 to 2004, birth weight did not change, weaning weight increased by1 lb, yearling weight by 2 lb, and milk by 2 lb. For whatever reason, these two breeds bucked the tendency over the last 20 years for increased weights after birth. (Values from breed association web sites.)
EFFECTS OF GRAZING GAIN ON FEEDLOT PERFORMANCE
Texas A&M and Texas Tech researchers collaborated to compare gain on pasture to subsequent feedlot performance. Braunvieh-cross steers were grazed at different stocking rates on winter pasture from January to May at three Texas Agricultural Experiment Stations (Overton, Uvalde, and Vernon). All steers were then hauled to Texas Tech and fed for 111 to 113 days. Steers were classified into five groups based on their grazing gain; group grazing-ADG averaged 0 lb/day, 1.21 lb/day, 1.69 lb/day, 1.98 lb/day, and 2.24 lb/day. This resulted in group-average initial feedlot weights, respectively, of 695 lb, 805 lb, 843 lb, 873 lb, and 893 lb. In general, feedlot ADG (averaging 3.78 lb/day overall) for the five groups did not differ significantly, and the same was true for carcass characteristics. In contrast to these results, most studies have shown that cattle whose gains are restricted will compensate by gaining faster in subsequent periods, when nutrition is adequate. (J. Animal Sci 81:168, Suppl. 1)
CATTLE NUMBERS FINALLY INCREASING
For the first time since 1995, January 1 cattle numbers increased. Beef cows are up about 240,000 head (0.6 percent) from a year ago, heifers saved for replacements are up about 220,000 head (4 percent), and total cattle numbers are up a little less than a million head (1 percent). However, last year’s calf crop was the smallest in over 10 years, down about 1 percent from a year ago. All this means that feeders should be in short supply for awhile, but more cows should change that in two to three years. We’ll see. (USDA – National Agricultural Statistics Service)