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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #75767
Title: INFLUENCE OF SIRE TYPE, MATURITY, AND NUTRITIONAL BACKGROUND ON CHOLESTEROLAND FATTY ACIDS OF THE GROUND CARCASS AND LONGISSIMUS OF BEEF STEERS

Author
item RULE, DANIEL - UNIVERSITY OF WYOMING
item Macneil, Michael
item Short, Robert

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Commonly used sire breeds that are diverse, in so far as lean vs fat growth, do not interact with nutritional background or maturity to affect muscle cholesterol. Fatty acid composition can be modestly changed by this type of interaction such that steers raised by backgrounding, followed by pasturing during summer, and then feedlot- finished produce muscle with optimal ratios of neutral and hypocholesterolemic to hypercholesterolemic fatty acids. Even if this beef is USDA Choice, a 3 oz serving of closely trimmed beef will contribute only about 14% of the recommended daily cholesterol intake. Thus, by utilizing breeding systems that emphasize high lean growth potential and moderate fat deposition, along with a strong backgrounding regimen, beef with lipids that fall well within current health guidelines is readily achievable.

Technical Abstract: The purpose of this study was to ascertain how diverse beef cattle production systems affect fatty acids and cholesterol of meat. Steers were sired by either high-index (HI) Charolais bulls (high lean and moderate fat) or average-index (AI) Hereford bulls (average lean, high fat). Rearing systems included: Spring-born calves (C) weaned directly into the feedlot at 6 mo, slaughtered at 90-d intervals; fall-born yearlings (F) weaned onto pasture, feedlot-finished, slaughtered at 14, 16, or 18 mo of age; spring-born yearlings (Y) weaned onto a growing diet during winter, pastured in summer, feedlot-finished, slaughtered at 18 (off grass), 19.5, 21, or 22.5 mo of age. Four steers of each type were slaughtered in each of two years for each management-age group. Fatty acids and cholesterol of ground carcass (GC) and longissimus (LD) were determined by GLC. Carcass fat increased faster in AI than in HI steers (P < .01). GC cholesterol was greater for AI steers (P=.06) than HI steers because of the greater fat content of the AI GC. No differ- ences in LD cholesterol were observed for any group of either sire type. Fatty acid differences in GC with maturity were due primarily to de- creases in 18:0 and increases in 18:1. LD saturated and monounsaturated fatty acids changed little with maturity, but total saturates were greater for AI (44.5%) than for HI (42.8%) (P=.02). Group Y steers of HI sires had the greatest (P=.04) ratio of 18:0 plus unsaturates to 14:0 plus 16:0 (most hypocholesterolemic). We conclude that cholesterol in lean muscle is not altered by the sire x maturity x nutrition imposed, and that lean beef from steers by HI bulls and backgrounded before finishing may produce meat with the healthiest lipid composition.