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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Grain Or Pasture Finishing Systems on Carcass Composition and Tissue Accretion Rates of Lambs

Authors
item Murphy Timothy A, - OHIO STATE UNIV
item Loerch Steven C, - OHIO STATE UNIV
item Mcclure Ken E, - OHIO STATE UNIV
item Solomon, Morse

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 1994
Publication Date: N/A

Interpretive Summary: Today's consumers are demanding leaner meat products because of perceptions that fat consumption leads to health problems. The type of finishing (feed) system used for ruminant animals has been shown to affect the time required for finishing the animal as well as the efficiency of feed utilization by the animal. This study evaluated grain versus pasture-finishing systems on carcass composition and growth efficiency. Finishing lambs on forages leads to leaner carcasses. The increases in carcass leanness with forage finishing were not due to increased lean accretion but rather due to decreased fat production. One of the biggest benefits to forage-based finishing systems for ruminants may be the improved efficiency of production and reduced waste for end product processing.

Technical Abstract: The effects of finishing system on performance and carcass composition were determined in an experiment utilizing 40 crossbred, early weaned lambs (28 kg BW). Finishing systems were 1) grazed alfalfa, 2) 100 percent concentrate diet fed in drylot, and 3) grazed ryegrass for 42 d followed by an all concentrate diet fed in drylot. All lambs were fed to similar final weights (48 kg). Average daily gain was greatest for lambs placed directly in the feedlot compared with the other two finishing systems. Differences in ADG led to an increase of 33 and 50 d on feed for the lambs finished with alfalfa and those initially grazing ryegrass, respectively, compared with placement directly in the feedlot. Although all lambs were fed to a similar final weight, carcass side weight was approximately 1 kg less for alfalfa-finished lambs compared with the other two finishing systems. The quantity of separable lean tissue and bone were not affected by finishing system. However, quantity of total fat and each of the three major fat depot sites (subcutaneous, seam and mesenteric) were reduced in alfalfa-finished lambs compared with finishing systems involving concentrate feeding at some time during the finishing system. Composition of individual primal cuts revealed reductions in total separable fat with alfalfa finishing compared with the other two systems. However, chemical composition of the lean tissue within the primal cuts was not affected by finishing system, with the exception of the loin and breast. Finishing systems based on grazed forage can lead to the production of leaner carcasses but consumers may not see a major difference in the composition of consumable product.

Last Modified: 9/1/2014
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