Pietro Giaccone

Multivariate factor analysis of Girgentana goat milk composition

Abstract The interpretation of the several variables that contribute to defining milk quality is difficult due to the high degree of correlation among them. In this case, one of the best methods of statistical processing is factor analysis, which belongs to the multivariate groups; for our study this particular statistical approach was employed. A total of 1485 individual goat milk samples from 117 Girgentana goats, were collected fortnightly from January to July, and analysed for physical and chemical composition, and clotting properties. Milk pH and tritable acidity were within the normal range for fresh goat milk. Morning milk yield resulted 704 ± 323 g with 3.93 ± 1.23% and 3.48±0.38% for fat and protein percentages, respectively. The milk urea content was 43.70 ± 8.28 mg/dl. The clotting ability of Girgentana milk was quite good, with a renneting time equal to 16.96 ± 3.08 minutes, a rate of curd formation of 2.01 ± 1.63 minutes and a curd firmness of 25.08 ± 7.67 millimetres. Factor analysis was performed by applying axis orthogonal rotation (rotation type VARIMAX); the analysis grouped the milk components into three latent or common factors. The first, which explained 51.2% of the total covariance, was defined as “slow milks”, because it was linked to r and pH. The second latent factor, which explained 36.2% of the total covariance, was defined as “milk yield”, because it is positively correlated to the morning milk yield and to the urea content, whilst negatively correlated to the fat percentage. The third latent factor, which explained 12.6% of the total covariance, was defined as “curd firmness,” because it is linked to protein percentage, a30 and titatrable acidity. With the aim of evaluating the influence of environmental effects (stage of kidding, parity and type of kidding), factor scores were analysed with the mixed linear model. Results showed significant effects of the season of kidding and parity on common factors, while no differences were found between goats with one or more kids. The multivariate factor analysis technique was effective in describing the quality of Girgentana milk with a low number of new latent variables. These new variables have been useful in the study of the effect of some technical factors such as parity and season of kidding on the quantitative and qualitative aspects of milk production in this goat breed.

Demographic characterization and genetic variability of the Girgentana goat breed by the analysis of genealogical data

Abstract The aim of this paper is to present an overview of the actual Sicilian Girgentana population structure by the analysis of genealogical data. Statistics show that in 1983 the population consisted of 30,000 Girgentana goats; ten years later almost 98% of the entire Girgentana population disappeared. The remaining population consists of 461 individuals (134 males and 327 females), with 368 living animals. The effective population size is 380 individuals. The inbreeding rate per generation was equal to 0.13%. The average estimated inbreeding level within the living male population was equal to 0.8% (0-15%); and the average inbreeding level within the living female population was equal to 0.7% (0-31%). The average relationship between males and females estimated on 27,772 possible matings was equal to 0.5% (0-8.7%). The estimated inbreeding level was not high due to the lack of pedigree information. This is resulting in a ratio between the number of founder equivalents (ƒe = 22,94) and the number of absolute founders (ƒa = 93) equal to 25%.

Factors associated with milk urea concentrations in Girgentana goats

Abstract A total of 1,481 milk samples of 166 Girgentana goats, taken along the entire lactation, were utilised to evaluate the effect of non nutritional factors on milk urea (MU). Parity, stage of lactation and month of sampling significantly influenced MU, while no effect was found for born kids number. The first kidding goats produced lower MU than multiparous goats. Trend of MU was similar to milk production course with a peak found at 60 DIM. The different MU levels between several months of production are often linked to pasture chemical variations.

The influence of somatic cell count on sheep milk composition and cheese-making properties

Riassunto Influenza del contenuto in cellule somatiche sulla composizione del latte ovino e sulle caratteristiche del formaggio. Allo scopo di valutare gli effetti del contenuto in cellule somatiche (CCS) sulla qualità del latte e del formaggio Pecorino, è stata condotta una prova in un allevamento di ovini Valle del Belice. Da febbraio a luglio, ogni 15 d, il latte di tutte le pecore in lattazione è stato analizzato per il CCS in modo da ottenere due tipi di latte, a basso (<1.000.000) ed alto (da 1.000.000 a 3.000.000) tenore in cellule. Sul latte di massa sono state effettuate le analisi chimiche (grasso, frazioni azotate, urea, lattosio, calcio, fosforo), citologiche (carica batterica, CCS), fisiche (pH, acidità titolabile, punto crioscopico) e tecnologiche (r, a30 e K20). Il latte di massa è stato caseificato separatamente per tipo di latte. I risultati hanno evidenziato una marcata influenza del CCS sulla qualità del latte, in accordo con quanto riportato in letteratura; nessuna influenza è stata osservata sui formaggi freschi e stagionati.

Utilization of mulberry leaves (Morus latifolia cv. Kokusou 21) in diets for dairy ewes

Abstract Twelve Valle del Belice lactating ewes were divided into three homogeneous groups and fed ad libitum the following diets in a 3x3 Latin square design: sulla hay (HA); sulla hay and Mulberry leaves (M. leaves) (HM); M. leaves (MU). DM intake of MU ewes was lower than that of HM ewes, with an intermediate level for HA ewes. HM ewes showed to prefer M. leaves to hay, but their need to balance the high protein and low NDF contents of M. leaves by eating hay also emerged. Milk yield increased as the dietary content of M. leaves increased In addition, the use of HM and MU diets led to higher milk fat and urea content in comparison with the HA diet. The results confirmed that M. leaves are a suitable fresh feeding source for sheep, and suggested to use them in association with fibre-rich feeds.

Phenotypic and genetic analysis of udder health using SCC in Valle del Belice dairy sheep

Riassunto Analisi fenotipica e genetica del contenuto in cellule somatiche sullo stato sanitario della mammella in pecore da latte di razza Valle del Belice. Le infezioni intramammarie (IMI) nell’allevamento dei piccoli ruminanti allevati per la produzione di latte rivestono una notevole importanza economica ed igienico sanitaria come evidenziato nelle direttive dell’Unione Europea 46/92 e 71/94. Nel presente lavoro è stata condotta una analisi fenotipica e genetica sulla suscettibilità di pecore da latte di razza Valle del Belice alle IMI. Con un threshold sire model sono state stimate le componenti della varianza e l’ereditabilità del carattere definito sulla base del contenuto in cellule somatiche del latte.