Donata Marletta

Genome-wide analysis of Italian sheep diversity reveals a strong geographic pattern and cryptic relationships between breeds.

Italy counts several sheep breeds, arisen over centuries as a consequence of ancient and recent genetic and demographic events. To finely reconstruct genetic structure and relationships between Italian sheep, 496 subjects from 19 breeds were typed at 50K single nucleotide polymorphism loci. A subset of foreign breeds from the Sheep HapMap dataset was also included in the analyses. Genetic distances (as visualized either in a network or in a multidimensional scaling analysis of identical by state distances) closely reflected geographic proximity between breeds, with a clear north-south gradient, likely because of high levels of past gene flow and admixture all along the peninsula. Sardinian breeds diverged more from other breeds, a probable consequence of the combined effect of ancient sporadic introgression of feral mouflon and long-lasting genetic isolation from continental sheep populations. The study allowed the detection of previously undocumented episodes of recent introgression (Delle Langhe into the endangered Altamurana breed) as well as signatures of known, or claimed, historical introgression (Merino into Sopravissana and Gentile di Puglia; Bergamasca into Fabrianese, Appenninica and, to a lesser extent, Leccese). Arguments that would question, from a genomic point of view, the current breed classification of Bergamasca and Biellese into two separate breeds are presented. Finally, a role for traditional transhumance practices in shaping the genetic makeup of Alpine sheep breeds is proposed. The study represents the first exhaustive analysis of Italian sheep diversity in an European context, and it bridges the gap in the previous HapMap panel between Western Mediterranean and Swiss breeds.

Bioactive peptides in dairy products

Abstract Bioactive peptides are specific protein fragments that have a positive impact on body functions and conditions and may ultimately influence health. Most of the biological activities are encrypted within the primary sequence of the native protein and can be released by enzymatic hydrolysis and proteolysis or by food processing. Milk is a rich source of bioactive peptides which may contribute to regulate the nervous, gastrointestinal and cardiovascular systems as well as the immune system, confirming the added value of dairy products that, in certain cases, can be considered functional foods. The main biological activities of these peptides and their bioavailability in dairy products are reviewed. The natural concentration of these biomolecules is quite low and, to date one of the main goals has been to realize products enriched with bioactive peptides that have beneficial effects on human health and proven safety. Even though several health-enhancing products have already been launched and their integration in the diet could help in the prevention of chronic diseases such as hypertension, cancer and osteoporosis, more clinical trials are required in order to develop a deeper understanding of the activity of biopeptides on the human physiological mechanisms and also to assess the efficacy of their effects in a long term view. New scientific data are also needed to support their commercialisation in compliance with current regulations.

Goat milk with different αS2-casein content: analysis of allergenic potency by REAST-inhibition assay

Abstract In goat at CSN1S2 locus, seven alleles have been observed, characterized by different levels of expression, and, in particular, a null allele CSN1S2 O that significantly influences protein composition of milk. In a local goat breed reared in the North East of Sicily, “Argentata dell’Etna”, the combined use of electrophoretic milk analysis (SDS-PAGE) and 11th exon genomic analysis (PCR-RFLP) made it possible to identify three genotypes respectively normal (CSN1S2 NN ), heterozygote for the null allele (CSN1S2 NO ) and homozygote for the null allele (CSN1S2 OO ). In 214 “Argentata dell’Etna” goats, CSN1S2 O allele has shown a frequency of 0.033. An immunological test, REAST-inhibition assay (REAST, reverse enzyme allergo sorbent test), was carried out on three lyophilized milk samples (casein and seroprotein fractions) produced by goats with different genotypes at CSN1S2 locus, in order to assess their allergenic potency. By comparing the C 50 , the casein fraction CSN1S2 NN turned out to be the most allergenic, followed by the fraction CSN1S2 OO with 60% potency compared to the first one, while the fraction CSN1S2 NO presented 54% potency compared to the first one.

A simple model to predict the herbage intake of grazing dairy ewes in semi-extensive Mediterranean systems

The objective of this study was to develop a model to predict herbage intake of dairy lactating ewes during grazing in semi-extensive Mediterranean systems. For this purpose a total of 670 individual intakes from 210 Comisana and Pinzirita lactating ewes were collected in Sicily over 8 years of trials. The relationships between herbage intake and characteristics of the pasture (biomass availability, DM, CP and NDF content, herbage height), the animal (live weight, milk production) and the supplement (grams of DM and CP supplied daily to each animal) were investigated. Processing of data resulted in the formulation of two linear equations diversified for two qualitative levels of the pasture recognizable from the CP content of the herbage (CP >16% DM and CP ≤16% DM). Of the variables analysed, biomass, herbage height, herbage DM content, milk production and feed supplement, expressed as grams of CP individually offered each day, were those significantly correlated with ingestion. Inclusion of these variables in the model provides good reliability in predicting ingestion. The r2 values were 0.45 for CP ≤16% and 0.54 for CP >16%.

Effects of shearing and supplemental level on intake of dry ewes grazing on barley stubble

Twenty-eight Comisana dry ewes were utilised to evaluate the effect of shearing (14 shorn and 14 unshorn ewes) and supplemental level (100 and 300g of concentrate) on intake of barley stubble. Shorn ewes showed a small increase in dry matter intake (at the end of August: 1.32 vs. 1.10kg/day; p<0.01). Intake of barley stubble decreased as supplement level increased (mean: 1.18 vs. 1.29; p<0.01). On average, substitution effect was 0.63. Total lamb weight per ewe was greater in the group receiving 300g of concentrate (7.38 vs. 5.85; p<0.05). Shearing induced a small, but not significant decrease in total lamb weight per ewe (6.18 vs. 7.05kg/ewe). Results seem to indicate that unshorn ewes react better to environmental stress and that 300g improve reproductive performance.

Molecular characterization and genetic structure of the Nero Siciliano pig breed

Nero Siciliano is an autochthonous pig breed that is reared mainly in semi-extensive systems in northeastern Sicily. Despite its economic importance and well-appreciated meat products, this breed is currently endangered. Consequently, an analysis of intra-breed variability is a fundamental step in preserving this genetic resource and its breeding system. In this work, we used 25 microsatellite markers to examine the genetic composition of 147 unrelated Nero Siciliano pigs. The total number of alleles detected (249, 9.96 per locus) and the expected heterozygosity (0.708) indicated that this breed had a high level of genetic variability. Bayesian cluster analysis showed that the most likely number of groups into which the sample could be partitioned was nine. Based on the proportion of each individuals genome derived from ancestry, pigs with at least 70% of their genome belonging to one cluster were assigned to that cluster. The cluster size ranged from 7 to 17 (n = 108). Genetic variability in this sub-population was slightly lower than in the whole sample, genetic differentiation among clusters was moderate (FST 0.125) and the FIS value was 0.011. NeighborNet and correspondence analysis revealed two clusters as the most divergent. Molecular coancestry analysis confirmed the good within-breed variability and highlighted the clusters that retained the highest genetic diversity.

Donkey Milk Proteins: Digestibility and Nutritional Significance

Donkey milk is particularly recommended for infant nutrition as substitute of cow milk in case of sensitive neonates (showing cow milk protein allergies). Its protein compo‐ sition and the ratio between caseins and whey proteins reveals a high similarity with human milk, thus, in the last 10 years, an increasing interest arose to obtain a full characterisation of donkey milk proteins, here acknowledged. Digestibility data, mainly derived in vitro with human gastrointestinal enzymes, showed the high digestibility of donkey caseins and major whey proteins, except lysozyme and α-lactalbumin which proved to be quite resistant. The reported antimicrobial properties of donkey milk open concrete possibilities to use donkey milk as natural food preservative. Due to its attractive healthy properties, donkey milk was investigated for useful applications or to develop novel foods characterised by a high nutritional profile.

The mathematical modeling of the lactation curve for dairy traits of the donkey (Equus asinus).

In recent years, an increase in the number of donkeys farmed in Italy as a consequence of the growing demand for donkey milk for direct consumption has been observed. Some research has been carried out on jenny milk composition and on its nutritional properties, whereas milk production features are scarcely described for this species. In this work, the lactation curve shape of donkeys for milk yield and composition was investigated. A total of 453 test-day records for milk yield, fat and protein percentage, and somatic cell count of 62 lactations measured on 46 multiparous jennies of the Ragusano breed were considered. Effects of herd, age, and foaling season were assessed by using a mixed model analysis. Average and individual lactation curves were fitted using the Wood incomplete gamma function, the Cappio-Borlino modified gamma, and a third-order Legendre orthogonal polynomial model. Donkeys foaling between 6- and 10-yr-old had the highest test-day milk yield (about 1.85 kg/d). Donkeys foaling in winter and autumn had a higher daily milk yield compared with those foaling in summer and spring. Less defined results were obtained for composition traits. The general pattern of the donkey lactation curve is similar to the standard shape reported for the main dairy ruminant species, with a peak yield occurring at about 5 wk from parturition. Younger jennies tended to have lower production peaks and higher lactation persistency. Similarly to what is reported for dairy cattle, a large variability in individual patterns has been observed. No differences in goodness of fit have been observed between the models in the case of average lactation curves, whereas orthogonal polynomials were more efficient in fitting individual patterns.

Identification and Characterization of the Donkey CSN1S2 I and II cDNAs

The αs2 casein, encoded by the CSN1S2 gene, is one of the three Calcium sensitive caseins present in the milk of ruminants of zootechnical interest and in the milk of Equidae species (horse and donkey). In the present study, we cloned, sequenced and analysed two different donkey CSN1S2 cDNAs that we called CSN1S2 I and CSN1S2 II. The first, which spans over a fragment of 1016 nt, is constituted by 19 exons and encodes for a predicted protein (called αs2-I) of 221 aminoacids; the second, of which we determined the entire sequence (16 exons), encodes for a predicted peptide (called αs2-II) of 168 aminoacids. Alternative splicing and genetic markers are reported for both genes.

Melanocortin 1 receptor (MC1R) gene polymorphisms in three Italian cattle breeds

The Melanocortin 1 receptor (MC1R) is one of the main genes implicated in the determination of the coat colour in mammals. This locus showed a relevant genetic variation between breeds that can be exploited for breed traceability of the animal productions. Modicana, Cinisara and Sardo-Modicana are three Italian endangered cattle breeds. Genetic characterisation by molecular markers is a fundamental prerequisite for managing genetic resources and for developing potential genetic traceability protocols. In order to improve the knowledge on Modicana, Cinisara and Sardo-Modicana breeds and to evaluate the possibility to develop DNA-based protocols for their mono-breeds products traceability, the genetic structure of MC1R gene was analysed. Four main alleles were observed in a representative sample of 162 animals. In the black coated Cinisara breed (n = 42), the ED and E+ alleles segregated with a frequency of 0.93 for ED allele. In the red coated Modicana (n = 60) and Sardo-Modicana (n = 60) breeds the E+ and E1 alleles segregated with frequencies of 0.42, 0.57 and 0.52, 0.47, respectively. The recessive allele e showed a low frequency (0.01) in both breeds. Sequencing a subsample of 34 animals the rare E2 allele was found only in Modicana and Sardo-Modicana at a good frequency (0.50). A new PCR-RFLP test, based on BstOI restriction endonuclease, was devised to assay for this allele. Results of the work indicate that red coat in Modicana and Sardo-Modicana cattle is genetically determined by the E+ and E1 alleles instead of the e allele at homozygote status, as occurs in other red European breeds. In these three Italian breeds of local importance, MC1R polymorphisms can be used to discriminate Cinisara from Modicana and Sardo-Modicana, but it was not able to distinguish between the two red coat populations.