MANAGEMENT AND NUTRITIONAL STRATEGIES FOR YEAR-ROUND EWE MILK PRODUCTION WITH NON-TRADITIONAL DAIRY BREEDS
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Dairy sheep breeds around the world are seasonally polyestrous, with low conception rates during the increasing daylight period in spring and summer. As a result, sheep are milked seasonally, with one annual lactation per ewe. This dissertation tested the hypothesis that aseasonally polyestrous Finnsheep and Dorset meat breed ewes and their crosses could be milked in short and frequent lactations to achieve year-round ewe milk production, given nutritional strategies that supply high levels of fermentable fiber. This dissertation built a firm foundation for this hypothesis through an investigation of commercially milked meat and dairy crossbreed ewes, where ewes with comparatively low traditional dairy breed contribution achieved higher milk and milk component yields than ewes with more dairy genetics with similar lactation lengths. Further supporting this hypothesis, Finnsheep Dorset ewes, milked in a 22-month experiment managed in a year-round, accelerated lambing system with 1.67 lambings per ewe per year, achieved yearly milk yields comparable with traditional US dairy breeds. Milk component yields were influenced by dietary carbohydrate composition. Dietary recommendations derived from this investigation suggest a carbohydrate balance of 36.3% NDF and 37.2 % NFC, sourced from 42.4% soyhulls, 20.1% wheat midds, and 24.1% cornmeal in the dry matter to maximize both milk and milk component yields, independent of ewe breed composition. To further study opportunities to decrease lambing occurrence in year-round dairy systems, the ability of non-traditional dairy ewes for milking systems was further tested in a crossbreeding experiment with ¼ East Friesian dairy genetics. Ewes were managed in a year-round milking system for 1.5 lactations per ewe per year, with lactations being longer and less frequent than for ewes in the previous experiment. The out-of-season breeding ability of foundational Finnsheep Dorset crosses was retained in ¼ East Friesian (Finnsheep Dorset) ewes. Higher milk and milk component yield with 120-d lactations from ¼ East Friesian ewes fed with the previously recommended levels of NDF and NFC for Finnsheep Dorset ewes with shorter lactations suggest follow-up research with this aseasonal milk and meat breed hybrid. The results of this dissertation showed that milking non-traditional dairy ewes in short and frequent lactations is a viable strategy to achieve year-round ewe milk production.
Ewe milk; NDF; Sheep; Sheep milk
Barbano, David; Overton, Thomas; Brown, Dan
Ph. D., Animal Science
Doctor of Philosophy
dissertation or thesis