Studies on dairy production of milking ewes. I. – Estimates of genetic parameters for total milk composition and yield

Barillet, Francis F.; Boichard, Didier

doi:10.1186/1297-9686-19-4-459

Cited by 41 publications

(2 citation statements)

References 20 publications

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“…The genetic model was always supported by the data and heritability estimates were in line with estimated values previously reported for the respective traits in this breed (Othmane et al, 2002;El-Saied et al, 2006). However, the magnitude of the estimated heritabilities for these traits was lower than those reported for other dairy sheep breeds performing under less variable environments; for example, Lacaune (Barillet and Boichard, 1987). In dairy cattle, heritability estimates for FA content are in general lower than those for production traits.…”

Section: Repeatabilities Heritabilities and Ratios Of Permanent Varsupporting

confidence: 87%

Genetic determination of fatty acid composition in Spanish Churra sheep milk

Sánchez

Primitivo

Barbosa

et al. 2010

Journal of Dairy Science

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The objective of this study was to estimate the genetic variation of ovine milk fatty acid (FA) composition. We collected 4,100 milk samples in 14 herds from 976 Churra ewes sired mostly by 15 AI rams and analyzed them by gas-liquid chromatography for milk fatty acid composition. The studied traits were 12 individual FA contents (proportion in relation to the total amount of FA), 3 groups of fatty acids [saturated fatty acids (SFA), monounsaturated FA (MUFA), and polyunsaturated FA (PUFA)], and 2 FA ratios (n-6:n-3 and C18:2 cis-9,trans-11:C18:1 trans-11). In addition, percentages of fat and protein and daily milk yield were studied. For the analysis, repeatability animal models were implemented using Bayesian methods. In an initial step, univariate methods were conducted to test the hypothesis of the traits showing additive genetic determination. Deviance information criterion and Bayes factor were employed as model choice criteria. All the studied SFA showed additive genetic variance, but the estimated heritabilities were low. Among unsaturated FA (UFA), only C18:1 trans-11 and C18:2 cis-9,cis-12 showed additive genetic variation, their estimated heritabilities being [marginal posterior mean (marginal posterior SD)] 0.02(0.01) and 0.11(0.04), respectively. For the FA groups, only PUFA showed significant additive genetic variation. None of the studied ratios of FA showed additive genetic variation. In second multitrait analyses, genetic correlations between individual FA and production traits, and between groups of FA and ratios of FA and production traits, were investigated. Positive genetic correlations were estimated among medium-chain SFA, ranging from 0 to 0.85, but this parameter was close to zero between long-chain SFA (C16:0 and C18:0). Between long- and medium-chain SFA, estimated genetic correlations were negative, around -0.6. Among those UFA showing significant additive genetic variance, genetic correlations were close to zero. The estimated genetic correlations among all the investigated FA, milk yield, and fat and protein percentages were not different from zero. Our results suggest that low additive genetic variation is involved in the determination of the FA composition of milk fat in Churra sheep under current production conditions, which results in low values of heritabilities.

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Section: Repeatabilities Heritabilities and Ratios Of Permanent Varsupporting

confidence: 87%

Genetic determination of fatty acid composition in Spanish Churra sheep milk

Sánchez

Primitivo

Barbosa

et al. 2010

Journal of Dairy Science

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“…Les corrélations phénotypiques entre le lait et les taux sont négatives (Rp = -0,43 pour le TB, Rp = -0,45 pour le TP), tandis que la liaison phénotypique entre les 2 taux est nettement positive (Rp = +0,72). Ces valeurs sont parfaitement en accord avec des résultats antérieurs acquis en race Lacaune sur des fichiers de plusieurs milliers de données (Barillet, 1985(Barillet, , 1989Barillet et Boichard, 1987).…”

Section: Coefficients De Corrélation Phénotypique Entre Les Paramètreunclassified

Caractérisation de l'aptitude fromagère des laits de brebis Lacaune à l'aide d'un Formagraph

Delacroix-Buchet¹,

Barillet

Lagriffoul

1994

Lait

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-La présente étude visait à définir un protocole d'utilisation du Formagraph sur laits crus individuels non standardisés de brebis laitières. Des paramètres rhéologiques (R, k20, k30, aR) et physicochimiques (pH, taux protéique et butyreux) ont été mesurés sur 146 laits individuels entiers de 20 brebis Lacaune suivies pendant toute leur lactation. L'influence respective du pH et du stade de lactation est estimée, en même temps que la répétabilité des caractères contrôlés au cours de la lactation, de même que les corrélations phénotypiques entre toutes les mesures. En l'absence de standardisation des laits, il est indispensable de mesurer simultanément le pH et les paramètres rhéologiques, dans la mesure où le pH est un facteur de variation majeur des résultats rhéologiques. Les corrélations phénotypiques entre paramètres rhéologiques et composition du lait sont cohérentes avec celles observées pour le lait de vache. En particulier, la fermeté des gels est corrélée positivement (+0,59) au taux protéique. La variabilité individuelle des résultats et la répétabilité des mesures de paramètres rhéologiques, comparables à celles des taux protéiques et butyreux, est discutée du point de vue génétique. lait individuel de brebis 1coagulation à la présure 1stade de lactation 1corrélations phénotypiques Summary-Characterization of cheese making properties of individual Lacaune ewe milk samples with a Formagraph. The present study aimed at defining a method using the Formagraph apparatus with non-standardized individual ewe milk samples. Rheological (R, k20, k30, aR) and chemical (pH, protein and fat contents) parameters were determined on 146 individual whole milk samples from 20 Lacaune ewes sampled ail along the lactation. Respective effects of pH and lactation stage were estimated simultaneously with the repeatability of different traits from ewes recorded ail along their lactation, and the phenotypic correlations between ail the measurements, using a mixed model. Without milk standardization, it is essential to measure pH and rheological parameters at the same time, because pH is one of the main factors of variation of rheological results. Phenotypic correlations between rheological parameters and milk composition were in agreement with those published in cow milk. In particular, curd firmness is positively correlated with protein content (+0.59). Individual variability and repeatability of results of rheological parameters, comparable with those of the protein and fat contents, are discussed from a genetic point of view. individual ewe milk / renneting properties / lactation stage / phenotypic correlations

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Sheep Milk

and¹,

Wendorff²

2006

Handbook of Milk of Non‐Bovine Mammals

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Studies on dairy production of milking ewes. I. – Estimates of genetic parameters for total milk composition and yield

Cited by 41 publications

References 20 publications

Genetic determination of fatty acid composition in Spanish Churra sheep milk

Genetic determination of fatty acid composition in Spanish Churra sheep milk

Caractérisation de l'aptitude fromagère des laits de brebis Lacaune à l'aide d'un Formagraph

Sheep Milk

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