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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #357856
Research Project: Enhancing Sheep Enterprises and Developing Rangeland Management Strategies to Improve Rangeland Health and Conserve Ecology

Location: Range Sheep Production Efficiency Research

Title: Factors affecting ewe somatic cell count and its relationship with lamb weaning weight in extensively managed flocks

Author
item MURPHY, THOMAS - Montana State University
item STEWART, WHIT - University Of Wyoming
item Taylor, Joshua - Bret

Submitted to: Translational Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2018
Publication Date: 6/12/2018
Citation: Murphy, T.W., Stewart, W.C., Taylor, J.B. 2018. Factors affecting ewe somatic cell count and its relationship with lamb weaning weight in extensively managed flocks. Translational Animal Science. 2(suppl. 1):S159-S162. https://doi.org/10.1093/tas/txy031.
DOI: https://doi.org/10.1093/tas/txy031

Interpretive Summary:

Technical Abstract: The economic impact of mastitis in dairy species is well documented and efforts to reduce its prevalence through husbandry and genetic selection have been extensive. Females from non-dairy breeds are also prone to mastitis but since their udders are not regularly handled and their milk is not a commodity, its prevalence and economic impact are less clear. Milk was collected from individual halves from healthy ewes at Montana State University (MSU) and the U.S. Sheep Experiment Station (USSES) and somatic cell count was quantified and transformed to the log10 scale (LSCC). MSU milk was collected at approximately 5 (early) and 35 d (peak) after lambing, but only at peak lactation at USSES. Within each collection date, correlations between udder half LSCC were positive (P < 0.01) at both early (0.45) and peak lactation (0.35 – 0.92). However, correlations between udder half LSCC and composite LSCC (LSCCA) across collection dates were not different from zero (P = 0.33). Total litter weaning weight at 120 d (LWW) was analyzed separately for each flock. At MSU, early LSCCA negatively affected LWW (P < 0.01). Peak LSCCA reduced LWW at USSES (P < 0.01) but not at MSU (P = 0.87). On average, a unit increase in early or peak LSCCA was associated with a 12.8 and 14.8 kg decrease in LWW at MSU and USSES, respectively. Ewes at MSU that maintained low LSCCA (< 5.7) at both collections had greater (P = 0.02) serum Zn concentration (1.53 µg • mL-1) than ewes with low LSCCA in early and high LSCCA (= 5.7) in peak lactation (1.13 µg • mL-1). Overall, the percentage of ewes with high LSCCA was 19 and 17% at MSU and USSES, respectively. Subclinical mastitis, as inferred through SCC, is a prevalent and costly disease in these flocks and strategic Zn supplementation and other management practices to reduce its prevalence warrants further investigation.