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Casu S.,Research Unit Genetics and Biotechnology | Sechi S.,Research Unit Genetics and Biotechnology | Salaris S.L.,Research Unit Genetics and Biotechnology | Carta A.,Research Unit Genetics and Biotechnology
Small Ruminant Research | Year: 2010

The aim of this paper was studying the phenotypic and genetic relationships between udder morphology traits and udder health in dairy sheep. From 2000 to 2008 udder traits, somatic cell count (SCC) and clinical mastitis cases were recorded in an experimental flock consisting each year of around 900 ewes. A logistic regression was performed to evaluate the risk for a ewe of showing either a mastitis or at least 2 daily SCC records greater than 1 × 106 cells/ml in one of its lactations as function of udder traits scored in 1st lactation. 1587 individual udder scores and 39,950 SCC daily records were used for the analysis. Secondly, genetic correlation between lactation mean of somatic cell score and udder traits were estimated by a REML method applied to four bi-trait animal models, using data from 2251 primiparous ewes. Logistic regression results indicated that the risk of mastitis or high SCC values during the productive life increased as the cistern height increased and the degree of udder suspension and udder depth decreased. This suggests that the appraisal of the udder is a useful tool for culling decision aimed at increasing the sanitary status of the flock. The genetic correlation between lactation SCS and udder traits were favourable for udder depth (-0.50 ± 0.12), teat placement (0.39 ± 0.011) and degree of udder suspension (-0.42 ± 0.011) and closed to zero for the degree of separation of the two halves. Thus selection for udder morphology, already implemented in some dairy sheep breeds with the aim of improving machine milkability, will lead to a favourable correlated genetic response on SCC. © 2009 Elsevier B.V. All rights reserved. Source


Sechi S.,Research Unit Genetics and Biotechnology | Giobbe M.,University of Sassari | Sanna G.,University of Sassari | Casu S.,Research Unit Genetics and Biotechnology | And 2 more authors.
Small Ruminant Research | Year: 2010

The objective of this work was to investigate the effects of a single anthelmintic treatment on milk production. In 2008, in a flock of Sarda ewes naturally infected by gastrointestinal nematodes, 162 adult and 72 primiparous ewes were allocated into four groups. For each age class, one group was drenched with albendazole after lamb weaning whilst the other was left untreated as control. The efficacy of single anthelmintic treatment at the beginning of lactation was obtained by a faecal egg count reduction test. The effect of drenching on milk yield and components was studied both using single test date and lactation records. After 1 month geometric mean of eggs per gram of treated ewes decreased up to 1% of the initial value (3.40 eggs/g versus 322.63 eggs/g in primiparous and 2.14 eggs/g versus 312.70 eggs/g in adult ewes). The anthelmintic treatment showed a significant effect only on lactation milk yield of treated adult ewes that produced 19.2 L/year more than control ewes. Production level was investigated as a criterion to apply targeted selective treatment. High producer multiparous ewes produced 32.7 L/year more than control ones. Overall results confirm a beneficial effect of anthelmintic treatment on milk production without any detrimental effect on milk composition only on adult ewes markedly if high producers. Thus, depending on milk price and the required length of the period of discarded milk, the increased milk yield can counterbalance treatment's costs. © 2009 Elsevier B.V. All rights reserved. Source


Scala A.,University of Sassari | Varcasia A.,University of Sassari | Dore F.,University of Sassari | Solinas C.,University of Sassari | And 5 more authors.
Small Ruminant Research | Year: 2014

A field study was conducted to compare the effect of toltrazuril and diclazuril treatment against Eimeria infection in 142 naturally infected, weaned lambs aged 45-60 days. Lambs were divided into three groups of 48, 48 and 46 animals and treated with toltrazuril (20. mg/kg b.w.) and diclazuril (1. mg/kg b.w.). The last group of 46 lambs was left untreated as control. Oocyst faecal counts (OPG), Eimeria species and faeces consistency where assessed weekly from day 7 to day 63. In comparison with the control group, the OPG reduction on day 7 and 14 in toltrazuril-treated lambs was 99.1% and 97.4%, respectively, and 67% and 58% in lambs treated with diclazuril (p<. 0.005). On day 21, the percent of OPG reduction was still significant in toltrazuril-treated lambs (76.3%, p<. 0.05). Treatment with toltrazuril showed a decrease of Eimeria ahsata and E. crandallis oocysts at the time of maximum efficacy. The same effect was found in the diclazuril-treated group for E. ahsata only. No difference was found between the three groups regarding the consistency of the faeces (p>. 0.05). Body weight gains were determined at the start and the end of the study and showed a significant increase in the toltrazuril-treated lambs (p<. 0.001). These results suggested a greater efficacy of toltrazuril against subclinical eimeriosis in weaned lambs. © 2014 Elsevier B.V. Source

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