The Effects of Finishing Diet and Weight on Lamb Performance, Carcass Characteristics, and Flavor

Brady Campbell, Program Coordinator, OSU Sheep Team

The beauty of the small ruminant industry is that producers are able to capitalize on niche markets that surround religious holidays. Unfortunately, it is clear that the price of lambs at the sale barn has dropped as seen in recent market reports, with the conclusion of Christian and Orthodox Easter’s as well as Passover. Checking the calendar, it appears that we are approaching both Ramadan (month of fasting beginning May 6) and Eid al-Fitr (June 5-7). The occurrence of these religious holidays may allow for the lamb market to see an increase in market prices, but many fall and winter born lambs in the eastern US will also be entering the market as they approach finishing weights and in turn may flood the market. Therefore, as a producer, it is important to have a marketing plan in mind when making breeding decisions for proper lambing dates.

Aside from religious holidays, lamb is making a slow come back in the American diet as Millennials (people my age) and those passionate about food (foodies) have shown an increased interest in lamb products. In a recent lamb taste panel conducted at The Ohio State University by Jerad Jaborek, results showed that most American’s tend to favor a bland lamb flavor. Thinking along these lines, what are some major factors that influence lamb flavor and animal growth? To investigate this idea, the authors below compared lamb finishing diets and slaughter weights to determine their effects on lamb performance, carcass characteristics, and flavor.

In order to test this, lambs were fed either a high concentrate diet (concentrate-fed) in a dry lot or rotationally grazed on perennial ryegrass and fed grass hay (forage-fed) during the winter months. In addition, lambs were either fed to a slaughter weight of 121 lbs. (normal weight) or 170 lbs. (heavy weight) to determine the effects of finishing weight. Lambs were also separated by sex, ewes and wethers, but no differences between sexes were found.

From a performance standpoint, concentrate-fed lambs had an average daily gain (ADG) that was almost three times greater than forage-fed lambs (0.73 lbs./d vs. 0.26 lbs./d). At slaughter, the ADG of concentrate-fed lambs did not differ between normal and heavy slaughter weight lambs. When comparing forage-fed lambs, lambs slaughtered at a normal weight gained 33% faster when compared to heavy weight lambs. The authors mention that the low ADG seen with the heavy weight forage-fed lambs occurred during the last 55 lbs. of live body weight gain. This may be a result of their diet consisting of grass hay the winter months. In addition, it required 79 and 264 additional days for concentrate-fed and forage-fed lambs to achieve heavier body weights when compared to their normal weight counterparts.

From a carcass and meat quality standpoint, concentrate-fed lambs were fatter than forage-fed lambs when comparing lambs of the same slaughter weight. This was shown by a 0.16 in. increase in back fat in concentrate-fed lambs when compared to forage-fed lambs. In addition, when comparing heavy weight lambs vs. normal weight lambs, heavy weight lambs had a 0.20 in. increase in back fat. In a taste panel to determine meat quality, more off flavors and odors were associated with forage-fed lambs when compared to concentrate-fed lambs. There was also a greater incidence of off flavors associated with heavy weight lambs compared to normal weight lambs. Lamb flavor was rated better for concentrate-fed lambs when compared to forage-fed lambs. Slaughter weight did not affect lamb flavor among diet treatments. For tenderness and juiciness, heavy weight lambs were rated higher than normal weight lambs fed a concentrate diet, whereas forage-fed lambs did not show a difference in tenderness or juiciness between harvest weights.

Overall, concentrate-fed lambs finished earlier and spent less time on-farm when compared to forage-fed lambs. In addition, concentrate-fed lambs had fatter carcasses when compared to forage-fed lambs. The acceptability of concentrated-fed lambs was greater than forage-fed lambs as shown by a higher ranking in lamb flavor. This information demonstrates that depending upon your market of interest, there are alternative finishing diets and slaughter weights that can be used in order to fulfill a specific market depending upon the time of year and preference of the consumer.


Borton, R. J., S. C. Loerch, K. E. McClure, and D. M. Wulf. 2005. Comparison of characteristics of lambs fed concentrate or grazed on ryegrass to traditional or heavy slaughter weights. I. Production, carcass, and organoleptic characteristics. J. Anim. Sci. 83: 679-685.