mil P' Itry 'o Penn State Poultry | Pointers ENVIRONMENT AND IMMUNITY H. S. Siegel Professor of Poultry Science In a previous article (Lancaster Farming, October 3,1992), I dis cussed the ways that environmen tal factors influenced the number of disease organisms that the bird encounters, and pointed out that as concentrations of organisms increase the probability of infec tion also increases. Now I would like to discuss how the environment may affect the way in which the bird combats dis ease organisms after they enter the body. Most of an animal’s defense against disease depends on the activity of its immune system, which is generally divided into two major categories, humoral immun ity (antibodies) and cell-mediated PRICE EXTRA H 1-TORQUE RATED $315 $395 $490 T3eftSH€v ■■■ EQUIPMENT CO. immunity (direct action by cells of the immune system). Research has shown that a varie ty of stressors usually, but not always, can suppress both types of immunity. Stressors, such as temp erature extremes, crowding, toxins (mycotoxins, insecticides, etc.), can depress the ability of the immune system to produce antibo dies against specific disease organ isms or to directly attack foreign cells. The degree to which stress influ ences the immune system depends on the intensity of the hormone response of the bird. Much of the early research in chickens empha sized the role of two glands that produce the hormones ACTH (pituitary gland) and corticoster oids (cortisone-like hormones pro duced in the adrenal glands). It was shown that these hor mones, which increase during stress exposure, reduced the size of the lymphoid tissues, cardinal sites for cells necessary for immune HP RPM 1/3 1/2 3/4 1740 1740 1740 Th 10 PRICES EFFECTIVE UNTIL MARCH 31, 1993 We < Tal(e Customer Satisfaction (Personalty V SHAFT DfA. FRAME C 56 C 56 D 56 E 56 HS6H JS6HZ EIB2T JIB4T LIB4T H2IST K2IST L2IST 1 3/8 1 3/8 1 3/8 OMAHA, Neb. Several of the nation’s largest and most prominent feedlots have announced their intent to purchase and feed Shorthorn crosses as their preferred feeder cattle. This announcement was made at a meeting of the American Shorthorn Association at the National Western Stock Show in Denver, Colo. function. Later we found that ACTH or high temperature increased the amount of corticos teroids that are bound to the lymph cells. We now have shown that not only are some of these lymph cells reactive to corticosteroids but may also respond to the active form of thyroid hormone. There is now strong evidence that some cells of the immune sys tem produce their own hormones. Researchers at Penn State have described how certain groups of lymph cells of chickens secrete hormones that communicate to the rest of the body that the immune system is being activated. This “feedback” mechanism is part of a total integration of the healthy bird’s defense to combat disease. Any suppression of this mechan ism will lower the bird’s ability to resist disease. VOLTAGE 115/208-230 115/208-230 115/208-230 115/208-230 115/230 230 115/208-230 230 230 230 230 230 255 PLANE TREE DRIVE LANCASTER, PA 17603 (7-17) 393-5807 Shorthorns Receive Stamp Of Approval Personnel representing the feedlots and the order buying ser vice explained their renewed interests in demanding Shorthorn and Shorthorn cross calves as their preferred feeders. The ability of Shorthorn influenced feeder cattle to reach the USDA Choice grade at'~acceptable carcass weights at 14-15 months of age has been instrumental in cementing the fact that Shorthorn-sired cattle offer the greatest profit potential under a value based pricing system. Data generated at the USDA Meat Animal Research Center (MARC) at Clay Center, Neb., through the germ plasm evalua tion (GPE) study confirms that Shorthorn-sired calves presented the fewest calving problems and led all breeds in carcass perfor in mce with 88 percent USDA Choice carcasses at an average arc of 417 days, final weights of 1, 195 pounds, and yielded indus try demanded carcasses weighing 741 pounds. The National Beef Quality Audit completed last year con firmed that 45 percent of the cattle CATALOG NUMBER 113256 110086 110087 110088 110089 110090 130042 130043 130044 140203 140130 140414 Lancaster Farming, Saturday, February 20, 1993-C5 slmghtered have USDA Quality gr.idcs below choice. The audit showed the average beef carcass has nearly $2BO in lost value, with tlio majority of these losses bxause of excessive fat losses, p< or quality grades, and carcasses (and ribeyes) that are too large or too small for the consumer. The MARC data clearly shows that Shorthom-sired cattle most close ly meet the audit’s standards and offer the greatest profit potential under a value based marketing system. Ty McMurtury, head order buy er, indicated that he and his staff will travel to view the feeder calves at the ranch. Top dollar will be paid for top quality with the service costing the producer two percent of the gross sale. McMur tury indicated that he has orders for more than 1,200 head of qual ity feeder cattle daily to meet the demands of the fcedlots that he represents. Any questions and inquiries for additional information should be directed to the American Short horn Association in Omaha, Neb. r 1993 FFA WEEK, FEB. 20-27 WE SALUTE YOU I FARMERS AgCREOIT ( i corp. mm i I 9 East Main S treat, Utliz, PA Mjl I 717-626-4721 MJ David N. Groff RD 3 Lawlaburg, PA (717) 868-1420 Hont Grain Routing Raaat-li-Matic 3040 Panna Grova Rd. ' Grain imH^ Lincoln Unhf, PA 19352 Srtaa^arvtaT (Choator Co.) Cuotom Work (2 IB) 869-8834 Rotat-Cool UnH Available Schnupp’a Grain Roaating, Inc. R 0 S Lebanon, PA 1-800-402-4004 717-885-6811
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