Evaluation of growth, meat quality,

                           and sensory characteristics

                               of wool, hair, and

                                     wool/hair lambs

 University of Idaho

Performance Narrative:
Activities Performed:
Two University of Idaho (UI) Sheep Center breeding groups included Targhee/Polypay
ewes with a Suffolk ram and Targhee/Polypay ewes with a Dorper ram. Rams were
placed with the ewes October 1st and lambed between February 24th and April 4th. The
wool lambs (n=9) and the wool/hair lambs (n=9) were born at the UI Sheep Center, and
purchased by the research project at an average age of 69 days, the hair (Dorper)
lambs (n=9) were purchased from a local producer at an average age of 79 days. The
purchased lambs entered a 30-day quarantine and were placed on the same finishing
rations. Following quarantine, they were integrated into the same pen as the original
lamb groups. They were raised in the same environment until harvest on three separate
dates; 9/13/2021, 10/04/2021, and 10/18/2021.
Lambs were harvested at the UI Meat lab when they reached ~0.2 in of 12th rib fat
thickness as estimated by trained University of Idaho personnel. The goal was to have
three harvest dates taking three lambs from each group for a total of 9 lambs per
harvest day. The final harvest date contained two groups of two and one group of three
due to pulling two lambs for health reasons during the feeding period. At 48 hours
postmortem, each lambs carcass weight, back fat, back wall, rib eye area, % boneless,
closely trimmed retail cuts, conformation, flank streaking, quality grade, and yield grade
were measured. Carcasses were fabricated, and the lamb loin was removed, 1-inch
chops were then cut and aged at 0C until 10 days postmortem.
Following aging, the chops were weighed and placed in Styrofoam trays and
overwrapped with an oxygen permeable PVC film. They were displayed in a glass retail
display case at 2C for 4 days. Lean color, surface discoloration, and bone color were
measured daily by three evaluators following American Meat Science Association
Guidelines (AMSA, 2012). To avoid effects due to display case location, chops were
rotated after each measurement. To analyze instrumental color, chops bloomed for at
least 60 minutes before objective color measurements, taken once daily using a Nix
color sensor, on day 0 of retail display with subsequent measurements taken on days 1,
2, 3 and 4. The instrument was set to illuminant A and Commission International del
Eclairage (CIE) L*, a*, and b* values were recorded. On days 0 and 4 of retail display
samples were collected to measure thiobarbituric reactive substance (TBARS) an
indicator of lipid oxidation.

1.All Lambs have been harvested Weaning weights and finished weights have
been collected to evaluate growth rate. Carcass data has been collected to evaluate
carcass quality.

2. Shelf-life studies have been completed Color and lipid oxidation have been
completed over a 4-day simulated retail display period.

Challenges and Developments

1. Sick Lambs - Two lambs had to be removed from the study. One ended up having a chronic
prolapse and was not gaining weight. The other had bronchitis.

Outcome and Indicator Results to Date

1.Post-weaning growth rate Wool: 0.52lbs. Composite:  0.45lbs. Hair:  0.46lbs.

2. Carcass quality: CW: Wool: 71lbs. Composite: 54lbs.Hair:51lbs.BF:Wool:0.19in.Composite: 0.15in. Hair:0.14in.  REA:Wool; 3.0sq. in. Composite: 2.5 sq. in. Hair:  2.6 sq. in.   

Upcoming Activities

1 Tenderness measurement January, 2022

2 Sensory characteristics January, 2022

3 Volatile flavor compounds March, 2022

4 Fatty acid profile March, 2022