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Beef Cattle Browsing

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

January 2007

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.

RECENT BREED COMPARISONS AT U.S. MEAT ANIMAL RESEARCH CENTER
The U. S. Meat Animal Research Center at Clay Center, Nebraska has been evaluating genetic types and breeds of cattle since 1970. This has involved eight studies and included 38 breeds. In each study, or cycle, there has been about 9 or 10 years from the first mating of sires by artificial insemination through evaluation of their female offspring for lifetime production. Angus and Hereford sires have been included in all cycles, with overlaps of individual sires of these breeds across cycles to enable valid comparisons of all breeds. In the latest cycle, Angus and Hereford  sires were compared to Beefmaster, Brangus, Bonsmara (developed in South Africa and containing 1/2 Africander, 1/4 Hereford, 1/4 Shorthorn), and Romosinuano (a native Criollo breed developed in the late 1880’s in the Sinu valley of northern Colombia). These sires were bred to Angus and MARC III females (the latter a composite of 1/4 each Angus, Hereford, Red Poll, Pinzgauer). Results from the six sire breeds are tabled below:

*Difference between breeds larger than this value are significant at .05 level

Half-blood females sired by the six breeds were bred to calve first at two years of age and evaluated through their first three calf crops. For their first calves, Beefmaster- and Brangus-sired heifers tended to wean a higher percentage of heavier calves, so production per female exposed to breeding was significantly higher (about 25% more compared to the average of the other breeds). However, this was not true for second and third calf crops. (U. S. Meat Animal Res. Ctr. Germ Plasm Evaluation Program Prog. Rpt. No. 23)

GRASS HARVEST TIME vs. NUTRITIONAL CONTENT
Prior research has indicated that harvesting alfalfa and cool-season grasses in the afternoon resulted in higher digestibility compared to morning harvest. North Carolina State University researchers wanted to see if there were similar effects in warm-season grasses. They harvested gamagrass and switchgrass at 6 AM and 6 PM and stored all material as baleage. Harvested forages were then fed to steers of evidently high Angus breeding. Compared to the AM harvest, the PM had higher starch and nonstructural carbohydrate content and greater dry matter consumption, but there were no differences in apparent digestibility of dry matter or fiber components. However, because of greater consumption, animal performance should be higher from PM harvest. (J. Animal Sci. 85:276)

CONSUMPTION OF MEAT, POULTRY & SEAFOOD
USDA Economic Research Service data show some interesting trends over the last hundred years or so in consumption of meat, poultry, and seafood. Since the period of 1910-1919, U. S. per capita beef consumption has increased by 43%, veal decreased over 90%, lamb decreased 80%, pork increased 16%, and total meat increased 19%. However, chicken increased almost 600%, turkey over 1400%, and seafood 46%. Peak consumption time was: beef, 1970-79; veal, 1940-49; lamb, 1930-39; total meat, 1970-79; chicken, 2006; turkey, 1995; seafood, 2006. Since the peak of 80.9 lb of beef during 1970-79, consumption has fallen to 62.9 lb in 2006. However, beef consumption has been relatively stable over the last 15 years.  (Extracted from Michigan State University Beef Cattle Research Update, Winter, 2007)

POST-CALVING EFFECTS ON 2-YEAR-OLD HEIFERS
Oklahoma State University researchers reviewed 53 reports published from 1970 to 2004 on the effect of post-calving nutrition and management in heifers calved first at two years of age. The review indicated that conception rates are similar in both first-calving and older females, but that longer post-partum intervals to first estrus (PPI) and decreased pregnancy rates are common in rebreeding first calvers. So, higher nutrition and management are required if acceptable performance is to be realized from rebreeding two-year-olds. Early weaning of calves notably decreases PPI and increases pregnancy rate. Dietary energy restriction has the opposite effect on those two responses, regardless of age or parity. Neither dietary fat nor undegraded intake protein supplementation consistently improved reproduction in first calvers.  Prebreeding exposure to bulls did decrease PPI and possibly increased first-service conception rates. The greatest positive effect on reproduction in rebreeding first calvers was realized from managing for adequate body condition at calving (Body Condition Score of 6 or higher) and providing adequate nutrition to minimize loss of condition and body weight after calving. The authors noted that positive effects from good management must be balanced against any corresponding costs. (Prof. Ani. Sci. 21:151)

FACTORS AFFECTING BROWSE CONSUMPTION BY CATTLE
Texas A&M researchers studied consumption of browse by cattle in the South Texas region. Samples from esophageal-fistulated steers were used to determine the percent consumption of grass, forbs, and browse and for analyses of crude protein and digestible organic matter. Fecal output was estimated using standard experimental procedures. Nutrient content of the samples and forage consumption (predicted from fecal output) were compared to published nutrient requirements to estimate dietary adequacy for 640 lb steers and 1140 lb dry and lactating cows. Energy proved to be the first limiting nutrient for all three classes of cattle. Average daily gain of steers dropped below 1 lb/day when browse reached from 5% to 30% of the diet. Energy levels dropped below that required for maintenance of dry cows at from 2% to 15% browse intake, and at only 2% for lactating cows. So, when lactating cows start consuming any browse, energy intake was inadequate for body weight maintenance. Finally, browse consumption above 20% generally occurred when availability of grass dropped below recommended minimum levels for predominant grasses in the experimental location. (Texas A&M – 2006 Beef Cattle Research in Texas, p. 119)