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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #115485
Title: USEFULNESS OF SUBJECTIVE OVINE MILK SCORES. I. ASSOCIATIONS WITH RANGE EWESCHARACTERISTICS AND LAMB PRODUCTION

Author
item Snowder, Gary
item KNIGHT, ARLIN - FORMER ARS RETIRED
item Van Vleck, Lloyd
item BROMLEY, C. - UNIV OF NEBRASKA
item Kellom, Thomas

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2000
Publication Date: 5/12/2001
Citation: Snowder, G.D., Knight, A.D., Van Vleck, L.D., Bromley, C.M., Kellom, T.R. 2001. Usefulness of subjective ovine milk scores. I. Associations with range ewes characteristics and lamb production. Journal of Animal Science 79:811-818.

Interpretive Summary: Range ewes are commonly evaluated for milking ability by producers as to the ewe's ability to rear lamb(s). The U.S. Sheep Experiment Station has subjectively scored (low, average, high) a ewe's milking ability within 24 hrs of lambing for many years. The relationship of subjective milk scores and lamb production was investigated in this study. Lambing records of Columbia (n = 1,731), Polypay (n = 1,129), Rambouillet (n = 1,704), and Targhee (n = 1,638) ewes were analyzed. At first lambing, very few ewes have a high milking score (1 to 10%). However, at second and later lambings, 29 to 40% of the ewes are evaluated as high for milking ability. At mature age, Columbia ewes (38%) have the highest percentage of high milk scores. Ewes with high milk scores give birth to significantly heavier lambs while ewes with low milk scores have significantly more lamb deaths at birth. Ewes with low milk scores weaned less total weight than ewes with hbetter milk scores across all age groups for all breeds. Differences for litter weight weaned between ewes with average and high milk scores are generally observed at 2 and 3 yr of age when litter weights were heavier among ewes with high milk scores for all breeds. Between the ages of 1 and 3 yr, Columbia, Polypay, Rambouillet and Targhee ewes with an average milk score wean significantly heavier litters (average differences of 10, 9, 13, and 12%, respectively) than ewes with low milk scores. This result suggests that milk score is an economically important trait and should be considered in breeding objectives; at a minimum, the incidence of low milk scores should be kept as small as possible. Subjective milk scores at lambing appear to be useful as a management tool for range sheep production systems to improve lamb survival, growth and overall lamb production.

Technical Abstract: Range ewes are commonly evaluated for milking ability by producers as to the ewe's ability to rear lamb(s). The U.S. Sheep Experiment Station has subjectively scored (low, average, high) a ewe's milking ability within 24 hrs of lambing for many years. The relationship of subjective milk scores and lamb production was investigated in this study. Lambing records of Columbia (n = 1,731), Polypay (n = 1,129), Rambouillet (n = 1,704), and Targhee (n = 1,638) ewes were analyzed. At first parity, only 1 to 10% of the ewes had a high milking score. However, at second and greater parities, 29 to 40% of the ewes were evaluated as high for milking ability. At maturity, Columbia ewes (38%) had the highest percentage of high milk scores. A positive association exists between ewe body weight and her milk score at third and later parities. Ewes with high milk scores gave birth to significantly heavier lambs while ewes with low milk scores were associated dwith significantly more lamb deaths at birth. Ewes with low milk scores weaned less total weight than ewes with better milk scores across all age groups for all breeds (P < 0.05). Lighter litter weights from ewes with low milk scores were linked to lighter birth weights and fewer weaned lambs. Differences for litter weight weaned between ewes with average and high milk scores were generally observed at 2 and 3 yr of age when litter weights were heavier among ewes with high milk scores (P < 0.05) for all breeds. Between the ages of 1 and 3 yr, Columbia, Polypay, Rambouillet and Targhee ewes with an average milk score weaned significantly heavier litters than ewes with low milk scores. Further support for the economic importance of milk score was the strong association between ewe milk score and individual lamb weaning weight within each age group.