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Grouping strategies and lead factors for ration formulation in milking ewes of the Chios breed |
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| Authors: | GE Valergakis G Arsenos Z Basdagianni G Banos |
| Institution: | aDepartment of Animal Production, School of Veterinary Medicine, Aristotle University of Thessaloniki, P.O. Box 393, GR-54124 Thessaloniki, Greece bChios Sheep Breeders Cooperative “Macedonia”, Thessaloniki, Greece |
| Abstract: | The aim of this study was to develop an efficient strategy for ration formulation for milking ewes of the Chios breed in Greece. The strategy involved two and three groupings according to production level and challenge feeding using lead factors. Lead factors, that adjust upwards the average production of a flock or a group of ewes, were calculated for the 83rd and the 90th percentile, using 49,237 milk test-day records from 549 flock-test-days, referring to 64 flocks and 97 complete lactations. Lead factors were 1.25 for the single-group, 1.14 and 1.17 for the two-group, and 1.11, 1.07 and 1.15 for the three-group strategy for the 83rd percentile. Regarding the 90th percentile, these were: 1.33 for the single-group, 1.18 and 1.19 for the two-group, and 1.15, 1.09 and 1.16 for the three-group strategy. Analysis of variance was used to assess the influence of several effects on lead factors. Flock-year and mean and standard deviation milk yield were significant (P < 0.05) in nearly all cases, leading to calculation of different lead factors for high (> 250 kg of milk/ewe/year) and low (< 250 kg of milk/ewe/year) producing flocks. Higher producing flocks were associated with somewhat lower than average lead factors, while the opposite was true for lower producing flocks. In order to allow the sufficient expression of the genetic potential of the best ewes and accurately estimate their genetic value under Greek conditions, the 90th percentile strategy can be adopted for the higher producing groups and the 83rd for the lower ones. |
| Keywords: | Chios breed Milk production Feeding strategy Grouping Lead factors |
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