Feeding Lambs: The Effect of Energy Source and Level, and Sex on Growth, Performance, and Carcass Characteristics of Lambs

Brady Campbell, Program Coordinator, OSU Sheep Team

As the month of May comes to an end, there are two thoughts that come to mind. One, early born lambs raised indoors on grain are approaching market appropriate condition (live body weight and fat cover). Two, according to the Ethnic Holiday Calendar provided by the Maryland Small Ruminant program, Eid ul-Fitr (the Festival of Fasting Breaking for the Muslim faith) begins in two weeks. With this being said, shepherds with available lambs may consider selling their lambs in order to capitalize on the increased market value of lamb as a major ethnic holiday approaches just prior to the summer slump. However, marketing lambs towards this type of niche market can be challenging as some holiday dates continuously change from year to year. Although it is too late for this year to change your diets, feeding program, and management practices, it is important to consider what diet your lambs are being fed in order to achieve these marketing goals for the future. Therefore, in order to understand how sex, feed source, and amount of feed offered per feeding affects lamb growth, performance, and carcass characteristics, this week Jaborek et al. (2017) provides us with the data to do just that.

Supported by the American Lamb Board, Jaborek et al. (2017) studied a total of 96 Dorset x Hampshire crossbred lambs fed one of three diets: 1) ad libitum whole shelled corn based diet (Ad Lib. WSC); 2) restricted fed corn based diet (85% of the ad libitum corn based diet; Limit-fed WSC); and 3) ad libitum alfalfa based diet (ALF). In addition, all diets were supplemented with vitamins, and minerals in a pellet. Main dietary ingredients were calculated on a per pound basis for whole shelled corn ($0.07/lb.), alfalfa ($0.27/lb.), and supplement ($0.23/lb.). Lambs were also penned and fed by sex, ewes or wethers. Lambs began the experiment weighing 66 lbs. Lambs were removed from trial and harvested to record carcass parameters once ewes and wethers reached 130 lbs. and 140 lbs. respectively.

From a growth and performance standpoint, lambs that were fed Ad Lib. WSC spent the fewest number of days on feed (88 days) when compared to Limit-fed WSC (105 days) and ALF (110 days) fed lambs. Lambs fed Ad Lib. WSC had the greatest average daily gain (0.82 lbs./day) when compared to lambs fed Limit-fed WSC (0.68 lbs./day) and ALF (0.64 lbs./day). In addition, lambs fed ALF had the greatest dry matter intake (4.42 lbs./day), with Ad Lib. WSC lambs falling intermediate (3.17 lbs./day), and Limit-fed WSC lambs consuming the least (2.80 lbs./day). When comparing feed cost of gain, lambs fed the Ad Lib. WSC had the lowest cost ($2.06/lb.), whereas Limit-fed WSC lambs fell intermediate ($2.37/lb.) and ALF fed lambs had the greatest feed cost per pound of gain ($10.17/lb.).

When comparing sex, wether lambs had an overall greater dry matter intake (3.54 lbs./day) compared to ewe lambs (3.38 lbs./day). However, there was not a difference in the number of days spent on feed when comparing wethers (102 days) and ewes (100 days).

From the standpoint of carcass evaluation, lambs fed one of the two WSC diets resulted in heavier carcasses and more overall fat, which resulted in higher dressing percentages (Ad Lib. WSC – 60.3% and Limit-fed WSC – 58.0%) when compared to ALF fed lambs (53.1%). In addition, lambs fed one of the two WSC diets had greater marbling scores and yield grades as compared to ALF fed lambs. Although not significantly different, lambs fed the ALF diet had a slightly smaller loin eye, but had the greatest percentage of boneless closely trimmed retail cuts as compared to either WSC diet fed lambs.

When evaluating different diets, lambs fed Ad Lib. WSC spent the fewest number of days on feed due to the greatest average daily gain. In addition, Ad Lib. WSC fed lambs had the lowest feed cost per pound of gain and fell intermediately with dry matter intake. However, lambs fed either WSC diet resulted in greater overall carcass fat and resulted in lower percentages of boneless closely trimmed retail cuts when compared to ALF lambs. Furthermore, sex did not play a significant role in lamb feedlot performance, other than wether lambs consuming more feed on a daily basis as compared to ewes. Therefore, when considering whether you will be pursuing ethnic markets or not in the future, be sure to keep the ethnic calendar in mind as well as the diet you are feeding. In order to achieve these marketing goals, your lamb feeding strategy may need to be adjusted in order to meet the continuously changing dates of ethnic holidays.

Be sure to join us next week as we share an additional lamb feeding study by Jaborek et al. that focuses on the implications of long fed lambs. This summary may apply to those lambs that were retained and continued to be fed out after the holiday, as they may have been too small or under finished to meet the demands of the current market.


Jaborek, J. R., H. N. Zerby, S. J. Moeller, and F. L. Fluharty. 2017. Effect of energy source and   level, and sex on growth, performance, and carcass characteristics of lambs. Small Rumin. Res. 151: 117-123.