Adaptation of the principles of selection for milk production to milking ewes: A reviewAdaption des principes de la sélection aux brebis laitières: une revueAdaption der selektionsprinzipien für milchschafe: eine uberblick
Abstract
The characteristics of the genetic improvement of milking ewes are discussed, taking into account the obvious fact that they are both dairy animals and sheep.
Two particular aspects of selection schemes are given:
- 1.
(1) the need to rationalize and simplify milk recording with a view to minimizing its cost in relation to the commercial value of the product per head.
- 2.
(2) the concurrent use of A.I. and natural mating.
This paper deals mainly with the situation in France (Lacaune breed). Several selection tools are used: simplified recording in large mechanized flocks (AC recording and B type recording), “Centres d'Elevage de Jeunes Mâles”, artificial insemination for good distribution of the daughters of selected rams between the flocks. Genetic progress is mainly realized in the selection flocks by artificial insemination with improved males, and outside the selection flocks with the sons of the improved males which are used in natural mating.
Résumé
Les traits caractéristiques de l'amélioration génétique des brebis laitières tiennent au fait qu'il s'agit a la fois d'animaux laitiers et d'ovins. En référence à cette réalité, deux aspects particuliers des schémas de sélection sont présentés:
- 1.
(1) la nécessité de rationaliser et simplifier le contrôle en vue de minimiser son coût compte tenu de la valeur commerciale des produits par animal
- 2.
(2) l'utilisation simultanée de l'insémination artificielle et de la monte naturelle
Le cas Français de la sélection des brebis Lacaune est plus particulièrement illustré. Le schéma fait appel à plusieurs outils: contrôle laitier simplifié dans de grands troupeaux mécanisés (contrôle AC et contrôle de Type B), Centres d'Élevage de Jeunes Mâles, insémination artificielle permettant d'obtenir une bonne distribution entre troupeaux des filles des mâles en testage. La diffusion du progrès génétique est réalisé dans les troupeaux de sélection par les mâles améliorateurs en insémination artificielle et dans les autres troupeaux par les fils de mâles améliorateurs en monte naturelle.
Zusammenfassung
Die Besonderheiten der genetischen Verbesserungen der Milchschafe rühren daher, dass es sich gleichzeitig um Milchtiere und um Schafe handelt. Angesichts dieses Tatbestandes werden zwei unterschiedliche Aspekte des Selektionsschemas vorgestellt:
- 1.
(1) Die Notwendigkeit die Kontrolle zu vereinfachen and zu rationalisieren, um die Kosten auf ein Minimum herabzusetzen und unter Berücksichtigung des Marktwertes der Produkte pro Tier
- 2.
(2) Ein gleichzeitiger Einsatz der KB und des Natursprunges.
Die französische Situation soil anhand der Selektion von Mutterschafen der Rasse Lacaune genauer beschrieben werden. Das Selektionskonzept zeigt mehrere Möglichkeiten auf: Vereinfachte Milchkontrolle in grossen Herden mit maschinellem Milchentzug (Kontrolle AC und Kontrolle Typ B), zentrale Aufzuchtstation der männlichen Nachzucht, Einsatz der KB zur Erzielung einer guten Verteilung der Töchter von Testböcken in verschiedenen Herden. Die Verbreitung des genetischen Fortschritts erfolgt über die positiven Vererber mittels KB in Selektionsherden. Ausserhalb der Selektionsherden werden die männlichen Nachkommen der Eliteböcke im Natursprung eingesetzt.
References (25)
- F. Barillet et al.
Facteurs de variation entre index père—fils en race Lacaune
- F. Barillet et al.
Optimisation de l'utilisation de l'insémination artificielle dans les schémas de sélection ovine
- J.G. Boyazoglu et al.
Aspects quantitatifs de la production laitière des brebis. II. Coefficients d'héritabilité
Ann. Zootech.
(1965) - R. Carta et al.
Simplification de l'échantillonnage en vue du contrôle laitier qualitatif des brebis et des chèvres
Ann. Génét. Sél. Anim.
(1972) - A. Charron
Le contrôle laitier ovin simplifié: bilan et comparaison de différents indices de classement des brebis
Mém. Ecole Sup. Agric. Angers.
(1979) - M. Cottier
Le contrôle laitier ovin simplifié dans la zone de Roquefort
- J.M. Elsen et al.
Etude de schémas de sélection applicables aux ovins
Bull. Tech. Dép. Génét. Anim.
(1974) - E. Eyal et al.
Lamb production in frequently lambing dairy sheep
World Rev. Anim. Prod.
(1973) - J.C. Flamant
Amélioration génétique de l'aptitude à la traite chez la brebis et les chèvres
- J.C. Flamant et al.
Le contrôle laitier ovin en France, ses modalités et son organisation: dossier réalisé par F. Barillet de l'Union Nationale des Livres Généalogiques
Acad. Agric. France. Séance
(1978)
Amélioration génétique de la production laitière de brebis Sardes. II. Facteurs de variations génétiques et non génétiques des performances des brebis ayant réalisé deux lactations
Ann. Génét. Sél. Anim.
Essai d'introduction des brebis de race Sarde dans le Rayon de Roquefort
Bull. Tech. Inf.
Cited by (7)
Improving the quality and safety of sheep milk
2010, Improving the Safety and Quality of Milk: Improving Quality in Milk ProductsIn this chapter we review the factors that affect the quality of sheep milk and examine the strategies that farmers can adopt to improve the quantity and quality of milk produced by their sheep. Some of these factors, such as the genotype of the sheep, are difficult to control, but farmers have control over others, such as the nutrition and management of the milking sheep. To obtain high quality milk the sheep must be milked regularly and completely, which implies adopting appropriate milking and cleaning routines and milking equipment. It is also important that the sheep are healthy and that they receive adequate diets. Environmental contaminants that potentially make the milk unsuitable for processing should also be avoided. These factors and their influence on milk quality for the processing of milk into dairy products, especially cheese, are described and critically examined.
Animal model evaluation of dairy traits in US sheep breeds, their crosses and three synthetic populations
1999, Small Ruminant ResearchMulti-trait animal model procedures allowed simultaneous estimation of year of record, age of ewe, litter size and genetic group, and the prediction of direct additive genetic merit, and non-genetic permanent maternal environmental effects of the dams with multiple lactations. Mixed model methodology was used to obtain estimated breeding values and estimated producing ability for total milk yield and percentages of fat, protein and lactose in the Dorset (D), Finnsheep (F), Lincoln (L) and Rambouillet (Ra) breeds and some of their crosses, the Romanov, Suffolk and Targhee breeds and three synthetic populations derived from crossbred foundations: Synthetic I (FXL), Synthetic II (DXRa) and Synthetic III (FXL)X(DXRa). Ranking of breeds was based on the mean values of mixed model solutions for direct additive genetic merit as deviations from their respective groups and non-genetic permanent maternal environmental effects of the dams. Among the purebreds, Suffolk ewes produced the highest volume of milk while the Finnish Landrace and Romanov ewes produced the lowest volume (6.8 vs −14.5 and −11.5, respectively). Productivity of synthetic populations was comparable to that of their purebred parents but lower than the crossbred parents. Crossbred ewes exceeded their purebred parents in milk yield (0.32 vs −6.15), possibly due to heterosis. In contrast, the percentages of fat (−0.07 vs −0.02), protein (−0.04 vs 0.02) and lactose content (0.01 vs −0.07) in the crossbred ewes were similar to those in the purebred ewes. Increased milk production in sheep could be beneficial in raising more lambs from multiple births common in the sheep breeds with a genetic background of the Finnsheep and Romanov inheritance. The genetic variation between and within domestic breeds reported here indicates an opportunity to develop higher milk producing strains for a commercial dairy sheep industry in North America. However, importation of European dairy sheep breeds is an alternative approach which might achieve that goal more rapidly and which is now being evaluated.
Diurnal Variation in the Somatic Cell Count of Ewe Milk
1994, Journal of Dairy ScienceThe hourly variation of SCC in milk throughout the period between milkings was studied in 60 half udders of 30 Manchega ewes (10 each in first, second, and third parities) for 2 consecutive d. The interval between milkings was 12 h. The effects half udder, sampling time and day, interaction hour by day, and parity were statistically significant and explained 58.9, 11.9, 1.3, .6, and .3%, respectively, of total variance. The hourly repeatabilities of SCC and log SCC within each day (.83 and .86, respectively) were high. The SCC increased 70% in the 1st h postmilking and then gradually decreased until the next milking. The variations in SCC from 6 h postmilking were statistically significant but of less quantitative importance than those from the previous hours. The mean SCC of a.m. and p.m. milkings were very similar on both days (112 and 114 x 103 cells/ml). The mean SCC difference of milk between a.m. and p.m. milkings was 14%. This variation could be considered to be normal in the ewe for an interval of 12 h between milkings.
These results suggest the standardization of time of sampling to avoid erroneous classifications of sheep based on SCC of milk.
Non-genetic effects on milk production of Latxa ewes
1993, Small Ruminant ResearchEffects of parity, lambing season, lactation length and interval of lambing to first recording of milk production of Latxa milking ewes were analyzed. One thousand records collected between 1983 and 1986 in the Basque Country (Spain) were studied. Milk yield averaged 138 (± 47) kg (CV = 34%) with 5.77 (±0.80) % fat (CV = 14%) and 5.07 (±0.41) % protein (CV = 8%). Negative correlation coefficients between milk yield and fat% (−0.27) and milk yield and protein% (−0.24) were found. Multiple correlations (R2) for the combined effects of parity, season, lactation length and record intervals on milk, fat and protein yields were 0.33, 0.39 and 0.44, respectively; while for fat% and protein% they were 0.19 and 0.33, respectively. Lambing season and lactation length were the most important effects (P ≤0.001 for all variables) on milk yield. Parity was highly significant (P ≤ 0.01) for milk, fat yields and protein%, but not significant for fat% and protein yield. The lambing to 1st recording interval was highly significant (P ≤ 0.01) only for protein%.
Se analiza el efecto del número de parto, la estación de parto, la longitud de la lactación y del intervalo desde el parto hasta el primer control lechero, sobre la producción de ovejas de raza Latxa. Se estudian un total de mil lactaciones recogidas en el País Vasco (España) entre 1983 y 1986. La producción lechera media fué de 138 kg (CV = 34%) con (CV = 14%) de grasa y 5.07% (CV = 8%) de proteína. Los coeficientes de correlación residuales entre cantidad de leche y% de grasa, y entre cantidad de leche y% de proteina fueron de −0..27 y −0.24, respectivamente. Los valores de R2 para el efecto combinado de número de parto, estación de parto, longitud de la lactación e intervalo desde el parto hasta el primer control, fueron de 0.33, 0.39 y 0.44, para kg de leche, kg grasa y kg proteína, respectivamente; mientras que para % de grasa y % de proteína fueron de 0.19 y 0.33, respectivamente. El efecto de la estación de parto y de la longitud de la lactación fueron los factores de mayor importancia (P ≤ 0.001 en todas las variables); mientras que el efecto del número de parto fué significativo para kg de leche, kg de grasa (P ≤ 0.001) y % de proteína (P ≤ 0.01); pero no para % de grasa y kg de proteína. El intervalo desde el parto hasta primer control lechero fue significativo (P ≤ 0.01) sólo para % de proteína.
Simplification of milk recording scheme in Latxa milking sheep
1992, Livestock Production ScienceSimplified methods of estimating milk yield and composition were evaluated on 1021 lactations of Latxa ewes. The standard method for recording milk production and composition in dairy cattle (monthly recording of two daily milkings) was used as a reference method to evaluate the accuracy and precision of the simplified methods studied. Five methods for simplification of quantitative and qualitative milk recording were examined: the ‘classical’ methods (recording every month) and three ‘punctual’ methods (recording only twice during lactation). The two classical methods (i.e. milk yield) were (1) a.m. recording only (AFM method), and (2) a.m. and p.m. recording alternately (ATM method). Punctual methods (i.e. milk composition) were (1) first- and second-month recordings (P12), (2) first- and third-month recordings (P13), and (3) second- and third-month recordings (P23). The main evaluation criterion used was the ‘variance of error’ (VE: ratio variance of the differences between actual and estimated production + variance of actual production). Among classical methods, ATM performed the best (VE ⩽ 3%) while P13 show the highest accuracy among punctual methods (VE, 5–30%). A recording program including an ATM scheme for milk yield and a P13 punctual scheme for milk composition is recommended for Latxa milking sheep.
Des méthodes simplifiées pour l'estimation de la production et de la composition du lait ontétéévaluées sur 1021 lactations de brebis Latxa. La méthode standard pour le controˆle de la production et de la composition du lait chez les vachies laitières (controˆle mensuel des deux traites journalières) aétéutilisée comme référence pourévaluer l'exactitude et la précision des méthodes simplifiées. Cinq méthodes pour la simplification du controˆle laitier quanlitatif ontétéexaminées. Les méthodes classiques (controˆle mensuel -) et trois méthodes ponctuelles (deux controˆles pendant la Les deux méthodes classiques (production laitière) ontété; 1) méthode AFM, controˆle AM seulement; et 2) méthode ATM controˆle AM ou PM alternativement. Les méthodes ponctuelles (caractáeristiques qualitatives du lait)étaient: 1) P12, controˆle du premier et deuxième mois; P13 controˆle du premier et troisième mois; 3) P23 controˆle du deuxieème et troisième mois. Le critère principal utilisédans l'évaluationétait la “variance de l'erreur” (apport de la variance des différences entre la production effective et estiméàla variance de la productive effective). Parmi les méthodes classique ATM a donnéles meilleurs résultats (VE≤3%), cependant P13 a montréla meilleure précition parmi les méthodes ponctuelles (VE de 5à30%). Un programme de controˆle laitier qui considère un schéma ATM pour la production laitière et le schéma ponctuel P13 pour la composition du lait est recommandépour les brebis laitières Latxa.
vereinfachte Methoden zur Schätzung von Milchleistung und Milchzusammensetzung wurden anhand von 1021 Laktationen von Latxa Auen evaluiert. Die Standardmethode zur Erhebung der Milchleistung und der Milchsuzammensetzung von Milchkühen (monatliche Aufzeichnung von zwei täglichen Gemelken) wurde als Referenzmethode verwendet, um die Genauigkeit der verwendeten vereinfachten Methoden zu vergleichen. Fünf Methoden zur Vereinfachung der Erhebung quantitativer und qualitativer Milchmerkmale wurden geprüft: zwei “klassisce” Methoden (monatliche Erhebung) und drei “punktuelle” Methoden (zweimalige Erhebung während der laktation).
Die zwei klassischen Methoden (z.B. Milcheleistung) waren: (1) nur morgendliche Erhebung (AFM-Methode), und (2) alternierende morgendliche oder abendliche Erhebung (ATM-Methode). Punktuelle Methoden (z.B. Milchzusammensetzung) warenj: (1) Erhebungen im ersten und zweiten Monat ()12), (2) Erhebungen im ersten und dritten Monat (P13), und (3) erhebungen im zweiten und dritten MOnat (P23). Das Hauptbewertungskriterium war die “Fehlervadanz” (VE) (Varianzverhältnis der Differenzen swischen wirklichen und geschätzten Produktionen + Varianz wirklicher Productionen). Bei den klassichen Methoden ergab die ATM die höchste (VE ≤3%) und bei den punktuellen Methoden zeigte P13 die höchste Genauigkeit (VE von 5–30%). Ein Erhebungsprogramm, das ein ATM-Schema für die Milchleistung und ein P13 punktuelles Schema für die Milchzusammensetzung miteinbezieht wird für Latxa Milchschafe empfohlen.
Evaluation of U.S. sheep breeds for milk production and milk composition
1992, Small Ruminant ResearchSeven standard, Dorset (D), Finnsheep (F), Lincoln (L), Rambouillet (R), Romanov (Ro), Suffolk (S), Targhee (T), and three synthetic breeds of sheep, Synthetic I (F×L), Synthetic II (D×R), and Synthetic III (F×L) × (D×R), were evaluated for milk yield (MILK, 1), average daily milk yield (ADY, ml) and contents of fat, protein, lactose and total solids in a five year lactation trial.
Highly significant differences were observed (P<0.01) among breeds for all traits (30 d postpartum after weaning) except percentages of fat and lactose. Average total milk yield was 65.51 in 122 d, and average daily milk was 533 ml. Suffolk were superior for MILK (83 liters) and ADY (680 ml), followed by Synthetic II. Lowest MILK and ADY values were recorded for Romanov (35 liters and 299 ml, respectively). Synthetic I ranked second lowest. Overall average fat content of milk was 6.0%, Suffolk produced the highest average (6.6%), followed by Dorset (6.5%). Lowest fat percentage was in Synthetic I (5.6%) milk. Overall average protein content was 5.8%; milk of Dorset, Romanov and Synthetic II was similar (6.1%) and ranked highest. Overall average lactose and total solids contents were 4.8% and 17.4%, respectively. Rambouillet ranked first for lactose (4.9%). Finnsheep had lowest percentages of milk protein and lactose (5.4% and 4.7%, respectively), and ranked second lowest for total solids (16.8%). Dorset excelled for total solids (18.2%). Targhee, Lincoln and Synthetic III were intermediate in all traits.
It was concluded that variation exists among and within U.S. sheep breeds for milk production traits. Overall performance for milk production was lower than “dairy” sheep breeds of Europe and Middle East. Introduction of superior non-U.S. germ plasm could result in faster genetic improvement than selection within existing U.S. breeds over many generations.