Use of a partial least squares regression model to predict Test Day of milk, fat and protein yields in dairy goats

A model able to predict missing test day data for milk, fat and protein yields on the basis of few recorded tests was proposed, based on the partial least squares (PLS) regression technique, a multivariate method that is able to solve problems related to high collinearity among predictors. A data set of 1731 lactations of Sarda breed dairy Goats was split into two data sets, one for model estimation and the other for the evaluation of PLS prediction capability. Eight scenarios of simplified recording schemes for fat and protein yields were simulated. Correlations among predicted and observed test day yields were quite high (from 050 to 088 and from 053 to 096 for fat and protein yields, respectively, in the different scenarios). Results highlight great flexibility and accuracy of this multivariate technique

Evaluation of connectedness in the registered population of the Sardinian dairy sheep breed

Connectedness across flocks of the registered population of the Sardinian dairy sheep breed was evaluated. Used criteria were: number of sires used in the same contemporary group; number of direct links and the average within and between contemporary group relationship coefficients. Dataset including yearlings’ first lactation records of 1990 and 2008 were compared to evaluate the effect of coupling artificial insemination with controlled natural mating on connectedness. An increase of number of sires and direct links were registered between 1990 and 2008. These results confirm that the across years prolonged use of well planned moderate rates of artificial insemination had a strong effect on the overall statistical connectedness across flocks so permitting more accurate estimations of the management and genetic effects. As a whole, the decreasing of the average relationship within flock coupled to a marked enhance of the average relationship between contemporary groups, indicates that the genetic connectedness of the Sardinian registered population presents a clearly increasing trend. This fact assures that current genetic evaluations are reliable across flocks

Demography and Genealogical Analysis of Massese Sheep, a Native Breed of Tuscany

This study investigates the genealogical and demographic trends of the Massese sheep breed in Tuscany from 2001 to 2021. The Herd Book kept by the Italian Sheep and Goat Breeders Association (Asso.Na.Pa) provided the data. The descriptive statistics were analyzed using JMP software. The pedigree parameters of a total of 311,056 animals (whole population—WP) were analyzed using CFC, ENDOG, and Pedigree viewer software. A total of 24,586 animals born in the period 2007–2021 represented the Reference Population (RP), and 18,554 animals the Base Population (BP). The demographic results showed an inconsistent trend of offspring registration. This study showed a short period of productivity for both ewes and rams, with means of 1.47 and 19.2 registered newborn ewes and rams, respectively. The genealogical analysis revealed incomplete data, highlighting inaccurate assessments of the relationships among the animals, and inbreeding with large differences among provinces. The average inbreeding coefficient in the WP was 1.16%, and it was 2.26% in the RP. The total number of inbreds was 2790 in the WP, with an average FPED of 13.56%, and 2713 in the RP, with an average FPED of 12.82%. The use of pedigree data is a key and economical approach to calculating inbreeding and relationship coefficients. It is the primary step in genetic management, playing a crucial role in the preservation of a breed. The regular updating of genealogical data is the first step to ensuring the conservation of animal genetic resources, and this study is compromised by the lack of such updates

Bilancio di 10 anni di selezione per la resistenza genetica alla Scrapie nella popolazione iscritta al Libro Genealogico della razza ovina Sarda

La selezione genetica per la resistenza alla Scrapie è stata avviata in Sardegna nel 2000. L’attività di selezione è stata rivolta inizialmente agli arieti del centro di FA della razza Sarda. Successivamente in seguito alle direttive dell’Unione Europea (Decisione 2003/100/CE) e delle Linee Guida Nazionali, è stato avviato nel 2004 il Piano Regionale della Sardegna (PR). Il PR inizialmente ha reso obbligatoria l’adesione solo agli allevatori iscritti al Libro Genealogico (LG). Nel 2009 l’adesione è stata resa obbligatoria a tutti gli allevamenti (Decreto Assessorato dell’Igiene e Sanità e dell’Assistenza Sociale n. 615/DecA/ 4 29/04/2009). L’obiettivo principale del PR è l’incremento della frequenza dell’allele resistente (ARR). L’attuale PR prevede l’impossibilità di movimentare arieti omozigoti sensibili (tipo ARQ/ARQ) in tutto il territorio regionale e stabilisce al 31 dicembre 2011 la data ultima per il loro utilizzo negli allevamenti. Il PR prevede anche l’adozione di una strategia selettiva che limiti l’impatto sul progresso genetico per i caratteri produttivi. A tal fine vengono fornite indicazioni affinché gli allevatori privilegino a parità di genotipo PrP arieti del LG. Inoltre, le norme che regolano il funzionamento degli arieti nel LG sono state modificate consentendo a giovani maschi non ancora provati per la produzione di latte ma con indice pedigree elevato e genotipo omozigote resistente di essere impiegati come padri d’ariete. Inoltre, al fine di recuperare importanti linee di sangue particolarmente valide per la produzione di latte ma di genotipo sensibile sono stati realizzati accoppiamenti tra arieti di elevato valore genetico per la produzione di latte con pecore omozigoti resistenti al fine di produrre una progenie resistente. L’obiettivo di questo lavoro è presentare il bilancio genetico delle attività di selezione al fine di verificare la potenziale disponibilità di genotipi resistenti di buon livello genetico per i caratteri produttivi per l’intera popolazione di razza Sarda

Effetto di polimorfismi in geni candidati sulle caratteristiche qualitative del latte ovino

La valutazione dei riproduttori negli ovini viene attualmente svolta attraverso i classici metodi di stima del valore genetico utilizzando le informazioni relative ai fenotipi ed ai rapporti di parentela. Dato il sistema di allevamento, la difficoltà ed il costo dei controlli funzionali e la scarsa efficienza della inseminazione strumentale non in tutte razze viene praticato il miglioramento genetico ed in ogni caso per il latte vengono valutati soltanto gli aspetti quantitativi della produzione (Carta et al. 2009). Tuttavia risultano di particolare interesse per il latte ovino gli aspetti nutraceutici con particolare riguardo al contenuto dei diversi acidi grassi per i quali è stata recentemente dimostrata l’esistenza di un determinismo genetico. L’individuazione dei geni responsabili delle caratteristiche quanti-qualitative del latte ovino permetterebbe quindi di aumentare l’efficienza del miglioramento genetico e di considerare nuovi obiettivi di selezione quali le caratteristiche nutrizionali e funzionali del latte. Una valida strategia per identificare i geni responsabili di un carattere è quella di verificare le associazioni tra polimorfismi di geni candidati (presumibilmente coinvolti nel carattere in base alla loro funzione o ad analogie con altre specie) e livelli diversi di espressione fenotipica. Per quanto riguarda la qualità del latte due geni: Delta 9 desaturasi (SCD) e il diacylglycerol acyltransferase1 (DGAT1) sono già risultati influenzare le caratteristiche della produzione di latte nei bovini (Mele et al. 2007) e negli ovini (Scatà et al. 2009). Lo scopo del lavoro è stato quello di associare polimorfismi dei geni codificanti per l’SCD e DAGT1 alle caratteristiche qualitative e quantitative del latte ovino

Genetic parameters for milk production and type traits in North American and European Alpine and Saanen dairy goat populations

The development of an across-country genomic evaluation scheme is a promising alternative for enlarging reference populations and successfully implementing genomic selection in small ruminant populations. However, the feasibility of such evaluations depends on the genetic similarity among the populations, and therefore, high connectedness and high genetic correlations between the traits recorded in different countries or populations are needed. In this study, we evaluated the feasibility of performing an across-country genomic evaluation for milk production and type traits in Alpine and Saanen goats from Canada, France, Italy, and Switzerland. Variance components and genetic parameters, including genetic correlations between traits recorded in different countries, were calculated using combined phenotypes, genotypes, and pedigree datasets. The (co)variance component analyses were performed within breed, either based only on pedigree information or also incorporating genomic information. Across-country genetic parameters were calculated for 3 representative traits (i.e., milk yield, fat content, and rear udder attachment). The heritability estimates ranged from 0.10 to 0.50, which are consistent with previous estimates reported in the literature. The genetic correlations for rear udder attachment ranged from 0.75 (between France and Italy, for the Alpine breed without genomic information) to 0.95 (between Canada and France, for the Saanen breed with genomic information), whereas for fat content, between France and Italy, they ranged from 0.75 in the Alpine breed without genomic information to 0.78 in the Alpine breed with genomic information. However, genetic correlations for milk yield were only estimable between France and Italy, with a moderate value of 0.45 for the Alpine breed with or without genomic information, and of 0.22 and 0.26 in the Saanen breed with and without genomic information, respectively. These low genetic correlations for milk yield could be due to several factors, including the trait definition in each country and genotype-by-environment interactions (GxE). The high genetic correlations found for fat content and rear udder attachment indicate that these traits might be more standardized across countries and less affected by GxE effects. Thus, an international genomic evaluation for these traits might be feasible. Further studies should be performed to understand the surprisingly lower genetic correlations between milk yield across countries. Furthermore, additional efforts should be made to increase the genetic connection among the Alpine and Saanen goat populations in the 4 countries included in the analyses