Friday, January 7, 2011

Comparison of lamb finishing diets

Researchers in Quebec, Canada, compared the growth performance and carcass characteristics of Dorset lambs fed different diets of concentrate and/or forage.  Forty male lambs, averaging 53 lbs., were used in the study. The four dietary groups were (1) ad libitum concentrates, (2) restricted concentrates, (3) zero grazing (forage), and (4) fresh grass (grazing).

Dietary group ADG (g/d) ADG (lbs/d)
 Ad libitum concentrate
 Restricted concentrate
 Zero grazing (forage)
 Fresh grass (grazing)

Compared to the lambs fed ad libitum concentrate, the lambs fed restricted concentrate diets required an additional 20 days to reach slaughter weight (103.4 lbs). The forage-fed lambs required 40 additional days of feeding.

The lambs fed ad libitum concentrate had better feed conversion than those on mixed or forage diets. Concentrate-fed lambs had higher body condition scores and carcass ratings than those fed mixed or forage diets.

As would be expected, the carcasses from the concentrate-fed lambs had more back fat than carcasses from any other feeding group. Carcass yields were also higher, attributed primarily to a lighter full digestive tract.

In contrast, forage feeding produced lambs with similar muscle development and color of lean, but with less fat.

Source: Small Ruminant Research Journal, November 2010.


meade_co said...

had some questions on your study. Why was the end weight only 103 lbs.? We feed lambs and feed to an end weight of 140 lbs. Our lambs would not have much for fat cover at 103 lbs. Also the feed cost has to enter into the equation. Free Choice rations in our country (western South Dakota) would run in the range of $220 to $230 a ton. What would be the cost of gains for the differnt rations.

On another note if 103 lbs. was your end point, why wouldn't you feed the lambs on pasture and go with a natural program or a grass fat program?

Susan Schoenian said...

This wasn't my study. I only have access to the abstract, so I can't answer specific questions. Most Dorsets don't have the genetic potential to finish much over 100 lbs. without getting too fat. The scientists were simply comparing performance and carcass traits of the four diets. Their conclusion was to finish lambs on pasture to produce a leaner product.