239 research outputs found
Resistenza genetica ai nematodi G.I. degli ovini: ricerca dei Quantitative trait locus (QTL) sul cromosoma 3.
No full textFRÈQUENCE DES DIFFÈRENTS GERMES RESPONSABLES DE MAMMITES CLINIQUES ET SUBCLINIQUES CHEZ LES PETITS RUMINANTS LAITIERS
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Grouping strategies and lead factors for ration formulation in milking ewes of the Chios breed
No full textThe 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 (P250 kg of milk/ewe/year) and low (</p
Studies on dairy production of milking ewes. I. – Estimates of genetic parameters for total milk composition and yield
No full textGenetic parameters for dairy traits in first lactation (milk yield, fat and protein yields, fat and protein contents) were estimated from records of 1487 Lacaune ewe lambs born from 102 young rams undergoing progeny test and 74 proven rams. Variance and covariance components were estimated by HENDERSON' methods I and III. According to the analysis, information from proven rams was totally or partially used for estimating fixed effects, or was excluded. Results appeared similar to the average literature data for dairy cows, except the correlation between fat and protein contents, which was rather high (0.8). The genetic standard deviation of fat was larger than that of protein, the ratio being about 1.3 for yields and 1.85 for contents. Accordingly, expected genetic change is likely to be smaller for protein matter than for fat matter. Whereas the genetic correlation between fat content and yield was positive, the genetic correlations between protein content and yield, or between content of one component and yield of the other, seemed to be close to zero and maybe negative. Accordingly, the selection criterion should include useful yield and content, instead of the useful yield alone. Useful yield (or content) was defined as a combination of fat and protein yields (or contents), with weighting 1 and 1.85 respectively.Les paramètres génétiques des caractères laitiers (quantité de lait, de matière grasse et de matière protéique, taux butyreux et protéique) sont estimés à partir d’un fichier de 1 487 agnelles de race Lacaune en 1er lactation, issues de 102 béliers de testage et 74 mâles de service. Ils sont estimés par décomposition de la variance et de la covariance entre demi-soeurs de père, en appliquant les méthodes I ou III d'HENDERSON' aux données de testage. L’information des pères de service est utilisée en totalité, partiellement, ou ignorée, pour estimer les effets fixés. Les résultats obtenus selon ces 3 analyses sont cohérents entre eux, et globalement conformes à la moyenne bibliographique connue en vache laitière, à l’exception de la corrélation génétique entre les taux butyreux et protéique qui ici apparaît plus élevée (0,8). La matière grasse est plus variable que la matière protéique, puisque le rapport des écarts-types génétiques est estimé à 1,3 pour les quantités et à 1,85 pour les taux. Les possibilités d’évolution génétique de la matière grasse sont donc plus importantes que celles de la matière protéique. Alors que la corrélation génétique entre le taux butyreux et la quantité de matière grasse est positive, les corrélations génétiques entre le taux protéique et sa matière, ou entre un taux et la quantité de l’autre matière, sont proches de zéro, et peut-être négatives. Il est conseillé en conséquence de sélectionner sur une combinaison linéaire de la quantité et du taux moyen de matière utile, plutôt que sur la matière utile seule. Les critères « quantité ou taux moyen de matière utile » sont eux-mêmes définis comme une combinaison des quantités (ou taux) de matière grasse et protéique, avec des pondérations économiques égales respectivement à 1 et 1,85
Le contexte de production des ovins laitiers en France : principaux objectifs de recherche-développement et conditions de leur mise en oeuvre
No full textLactation performance of does and growth rates of kids under different milking methods
No full text6th International Symposium on the Milking of Small Ruminants -- SEP 26-OCT 01, 1998 -- ATHENS, GREECEWOS: 000083860700061This experiment was conducted to compare different milking procedures for dairy goats. In the trial, German Fawn x Hair (native goat) first back-cross does (B-GI) that kidded singles were randomly assigned to treatment groups: (HU) milking half udder while kids were suckling the other half, (C) kids suckling all the milk in the morning and evening (control group), (ER) kids suckling all the milk in the morning and does milking in the evening and (ER+MR) kids suckling with residual milk in morning and evening. Measurements of milk yield, milk suckled and weights of kids were taken during the first 8 weeks of lactation. Results indicated that different milking and rearing methods increased commercial milk yield of does. Thus, the income of the farm can be improved by using the above-mentioned application.Int Sci Comm Hellenic Soc Anim Product, European Assoc Anim Product, European Cooperat Res Network Agr, Ctr Int Hautes Etudes Agronom, Int Comm Anim Recording, Greek Minist Agr & Culture & Sc
Caracteristiques constructives et du functionnement des installations de traite des ovins installees en Sardaigne
No full textvol. No. 95, p. 245-247, WAGENINGEN:Wageningen PERS, ISBN: 90-74134-64-
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