Comparison of selection criteria for milk yield traits of Valle del Belice dairy sheep

Portolano, Baldassare; Finocchiaro, R.; Kaam, J.B.C.H.M. van

doi:10.1016/j.livprodsci.2005.06.003

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…For these reasons, including milking length in the model may produce inaccurate estimates of fixed effects and cause an inappropriate reduction of the genetic variability. Consequently, lactation milk yields are often preadjusted for milking length before genetic evaluation (Barillet et al, 1992;Portolano et al, 2006). A method to estimate multiplicative adjustments for milking length of completed lactation records was set up by Carta et al (1998a).…”

Section: Genetic Evaluationmentioning

confidence: 99%

Invited review: Current state of genetic improvement in dairy sheep

Carta

Casu

Salaris

2009

Journal of Dairy Science

110

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Dairy sheep have been farmed traditionally in the Mediterranean basin in southern Europe, central Europe, eastern Europe, and in Near East countries. Currently, dairy sheep farming systems vary from extensive to intensive according to the economic relevance of the production chain and the specific environment and breed. Modern breeding programs were conceived in the 1960s. The most efficient selection scheme for local dairy sheep breeds is based on pyramidal management of the population with the breeders of nucleus flocks at the top, where pedigree and official milk recording, artificial insemination, controlled natural mating, and breeding value estimation are carried out to generate genetic progress. The genetic progress is then transferred to the commercial flocks through artificial insemination or natural-mating rams. Increasing milk yield is still the most profitable breeding objective for several breeds. Almost all milk is used for cheese production and, consequently, milk content traits are very important. Moreover, other traits are gaining interest for selection: machine milking ability and udder morphology, resistance to diseases (mastitis, internal parasites, scrapie), and traits related to the nutritional value of milk (fatty acid composition). Current breeding programs based on the traditional quantitative approach have achieved appreciable genetic gains for milk yield. In many cases, further selection goals such as milk composition, udder morphology, somatic cell count, and scrapie resistance have been implemented. However, the possibility of including other traits of selective interest is limited by high recording costs. Also, the organizational effort needed to apply the traditional quantitative approach limits the diffusion of current selection programs outside the European Mediterranean area. In this context, the application of selection schemes assisted by molecular information, to improve either traditional dairy traits or traits costly to record, seems to be attractive in dairy sheep. At the moment, the most effective strategy seems to be the strengthening of research projects aimed at finding causal mutations along the genes affecting traits of economic importance. However, genome-wide selection seems to be unfeasible in most dairy sheep breeds.

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Section: Genetic Evaluationmentioning

confidence: 99%

Invited review: Current state of genetic improvement in dairy sheep

Carta

Casu

Salaris

2009

Journal of Dairy Science

110

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“…

Valle del Belìce is a sheep breed reared in Sicily for milk production. The breeding history of this breed is relatively recent (Portolano, 1987). In the 1990s, the data collected on production and morphological traits allowed the development of Valle del Belìce breed standard.

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mentioning

confidence: 99%

A genome‐wide comparison between selected and unselected Valle del Belice sheep reveals differences in population structure and footprints of recent selection

Jemaa

Tolone

Sardina

et al. 2023

J Animal Breeding Genetics

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About three decades of breeding and selection in the Valle del Belìce sheep are expected to have left several genomic footprints related to milk production traits. In this study, we have assembled a dataset with 451 individuals of the Valle del Belìce sheep breed: 184 animals that underwent directional selection for milk production and 267 unselected animals, genotyped for 40,660 single‐nucleotide polymorphisms (SNPs). Three different statistical approaches, both within (iHS and ROH) and between (Rsb) groups, were used to identify genomic regions potentially under selection. Population structure analyses separated all individuals according to their belonging to the two groups. A total of four genomic regions on two chromosomes were jointly identified by at least two statistical approaches. Several candidate genes for milk production were identified, corroborating the polygenic nature of this trait and which may provide clues to potential new selection targets. We also found candidate genes for growth and reproductive traits. Overall, the identified genes may explain the effect of selection to improve the performances related to milk production traits in the breed. Further studies using high‐density array data, would be particularly relevant to refine and validate these results.

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Comparison of selection criteria for milk yield traits of Valle del Belice dairy sheep

Cited by 2 publications

References 15 publications

Invited review: Current state of genetic improvement in dairy sheep

Invited review: Current state of genetic improvement in dairy sheep

A genome‐wide comparison between selected and unselected Valle del Belice sheep reveals differences in population structure and footprints of recent selection

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