The Angus Journal® is a monthly magazine known for in-depth coverage of American Angus Association® programs and services; the Angus business; herd management; and advertising reflecting genetics and herd philosophies.
Issue link: http://angusjournal.epubxp.com/i/529629
74 n ANGUSJournal n July 2015 Midwest Region by Justin Sexten, University of Missouri, sextenj@missouri.edu Fly control and heat stress Producers gathering cattle for early pregnancy diagnosis or fetal sexing have the opportunity to implement fly-control methods while cattle are gathered. Fly control is important due to potential production losses and disease transfer. Horn flies are small blood-feeding flies found upside down on cattle backs in the morning, moving to the belly in the afternoon. Once horn-fly populations exceed 200 flies per animal they are reducing performance, decreasing gain by 10 lb.-20 lb. during the grazing season. Stable flies are another blood-feeding cattle pest, generally feeding on legs, and causing cattle to bunch up or stand in the water. Three to four stable flies per leg are the economic threshold. Stable flies complete their life cycle in decaying organic matter such as found around hay-feeding areas. Face flies are not blood-feeding pests but congregate around the eyes and nose where they feed on tears and other secretions. Face- fly populations are considered low, moderate and high at 5, 12-13 or greater than 20 per animal, respectively. Moderate to heavy populations can reduce grazing activity while causing eye irritation. Fly control can be achieved using a variety of methods, such as farm sanitation, pour-on dewormers, sprays, fly tags, dust bags or insect growth regulators in mineral and feed. Consider using multiple methods to increase control success while preventing resistance development. Disease transfer is the most common reason fly control is implemented. Producers attempt to reduce face-fly- induced pinkeye by implementing fly control. Remember, pinkeye is a complex disease caused by a number of factors — all related to eye irritation. Controlling face flies removes one of many potential sources of eye irritation. Anaplasmosis can also be transmitted by blood-feeding flies, while foot rot may be caused by flies forcing animals to congregate in ponds and streams to avoid fly bites. Flies increase maintenance requirements due to blood loss while reducing energy intake and grazing activity; the result is reduced animal performance. Flies also contribute to heat stress, causing cattle to bunch up and reducing animal cooling. Heat stress High environmental temperatures and the possibility of heat stress cannot be controlled; however, producers can manage heat gained from sun exposure and metabolic heat production in pasture settings. Providing natural or man-made shade will reduce heat gained by minimizing sun exposure. Shade can be detrimental if cattle do not have adequate space for air movement, similar to bunching due to flies. Shade requirements are not well-documented; however, recommendations for stocker cattle range from 15 sq. ft. to 30 sq. ft. per head, while mature cow requirements range from 30 sq. ft. to 40 sq. ft. of shade per head. To address reduced feed intake and increased energy requirements due to heat and parasite stress, pasture managers should maintain vegetative pastures. Grazing vegetative grass-legume pastures during summer stress periods offers increased energy density and minimizes metabolic heat production from digestion of mature forages. Preventing cattle from accumulating heat is the first step in preventing stress. As cattle accumulate heat, more energy is required for removal. When nighttime temperatures do not drop below 70° or wind movement is minimal during a period of two to three days, heat stress can become severe as accumulation may exceed the animal's ability to remove heat. To remove or dissipate heat, cattle sweat and pant. Sweating and panting are not as effective when relative humidity is high due to reduced evaporation. As a result, periods of high humidity and low wind tend to increase heat stress more than high temperature periods with low humidity and a brisk wind. Take advantage of shaded pastures; however, do not neglect the benefits of wind. Avoid pastures where vegetation blocks the wind without providing shade. Due to increased water loss from panting and sweating, water intake will increase 50% to 100%. Cattle may drink 2 gallons (gal.) of water per 100 lb. of body weight. Water intake is critical for all cattle classes, but Angus Advisor @ JULY herd management tips MANAGEMENT Guide to abbreviations and acronyms To make the "Angus Advisor" more concise and consistent, we have used the following abbreviations or expressions: $Values dollar value indexes ADG average daily gain AI artificial insemination AIMS Angus Information Management Software BCS body condition score BLV bovine leukemia virus BMP best management practices BQA beef quality assurance BRD bovine respiratory disease BRSV bovine respiratory synctial virus brucellosis Bang's disease BSE bovine spongiform encephalopathy BVD bovine viral diarrhea Ca calcium CHAPS Cow Herd Analysis and Performance System CP crude protein cwt. hundredweight DM dry matter EPD expected progeny difference ET embryo transfer FMD foot-and-mouth disease GnRH gonadotropin-releasing hormone IBR infectious bovine rhinotracheitis ID identification IM intramuscular in. inch lb. pound LCT lower critical temperature lepto leptospirosis Mg magnesium MiG management-intensive grazing MLV modified-live virus N nitrogen P phosphorus PI persistent infection PI 3 parainfluenza-3 virus preg-check pregnancy-check Se selenium sq. ft. square feet SPA Standardized Performance Analysis TB bovine tuberculosis TDN total digestible nutrients THI temperature-humidity index trich trichomoniasis Zn zinc