Carla Elia

Use of serum amyloid A and milk amyloid A in the diagnosis of subclinical mastitis in dairy cows

Mastitis is the most frequent and costly disease in dairy herds, as it negatively affects yield and milk quality. The presence of clinical mastitis is quite easy to asses, whereas the diagnosis of the subclinical form can be more difficult and requires laboratory assays. Somatic cell count (SCC) is widely used as a rapid and low-cost indicator of mastitis, even if is not useful in discriminating between the clinical and subclinical form. As amyloid A has been investigated as a marker of mastitis, the aim of this study was to assess the potential value of measuring amyloid A in serum and milk and the correlation with SCC in the diagnosis of subclinical mastitis. The reliability of two different ELISA kits for the measurement of amyloid A in milk was also tested. During a 1-month trial period, 21 cows were assigned to three experimental groups according to their health status: 6 cows with clinical mastitis (CM), 10 cows with subclinical mastitis (SM) and 5 healthy cows (HE). Amyloid A was measured both in serum (SAA) and in quarter milk samples (mAA) with a serum ELISA kit, and in quarter milk samples (MAA) with a milk ELISA kit. SCC, total microbial count (TMC) and bacterial examination of the milk were also carried out. After a log transformation, the data were submitted to ANOVA and linear regression. TMC was significantly higher in cows with clinical mastitis, while no differences were observed between the other two experimental groups. SCC and MAA levels were significantly different among the three groups. mAA concentrations were similar between cows with subclinical and clinical mastitis, and SAA was not affected by mastitis. A significant correlation between SCC and MAA or mAA was detected, while no correlation was recorded between SAA and mAA. A close relationship between MAA and mAA was noticeable even at low concentrations, suggesting MAA as a potential physiological marker of subclinical mastitis.

Effect of period of milk production and ripening on quality traits of Asiago cheese

Abstract After 6 and 12 months of ripening, samples of Asiago d’Allevo were analyzed for quality traits. Cheeses were produced during 3 periods using milk from cows fed a total mixed ration (TMR, May) or grazing on alpine pasture (AG) in early (July) and late (Sept.) summer. Data were submitted to ANOVA considering ripening, milk production period and farm as main effects, and whole cheese weight as covariate. During ripening, pH of AG-cheese was significantly lower than that of TMR-cheese; crude fat and protein significantly increased. According to period, July-samples showed the significantly lowest value of dry matter (DM), maybe due to a lower crude fat con-tent; however, variability in skimming method could have altered proximate composition. No texture differences were found, although increasing weight of whole cheese significantly reduced max shear force as result of a lower DM content. Lightness (L*) and yellowness (b*) significantly decreased during ripening. AG feeding system caused a lower L* and higher b* than TMR one, probably as a consequence of a different amount of milk pigments. Cheese varied also within AG season: Sept.-samples showed the lowest L* value and the highest b*.

Relationship between milk fatty acid composition and dietary roughage source in dairy cows

According to a 2 × 2 crossover design, 14 Holstein dairy cows were fed two isoenergetic diets based on either grass hay (GH) or maize silage (MS). Milk samples were collected during the third week of each period, and fatty acid (FA) profiles were analyzed using gas chromatography. The data obtained were subjected to ANOVA. Dietary treatment had no effect on either dry matter intake or milk yield. Milk from animals fed the GH-diet contained lower concentrations of saturated FAs (61.9 vs. 63.4% of total FAs; P < 0.05) and higher levels of polyunsaturated FAs (PUFAs) (6.1 vs. 5.8; P < 0.01). Feeding additional hay also increased conjugated linoleic acid and n-3 FA levels and decreased C16:0 levels. Increases in both PUFAs and n-3 FAs resulted in lower (P < 0.01) atherogenic and thrombogenic indices in milk from animals fed the GH diet compared with those fed the MS diet. A complete substitution of GH for MS appeared to improve milk FA profiles, even using different types of concentrates to provide a balanced diet.

Effect of castration age on carcass traits and meat quality of Simmental bulls

Riassunto Effetto dell’età di castrazione su caratteristiche della carcassa e qualità della carne di tori Pezzati Rossi. Il posticipo dell’età di castrazione sembra limitare la riduzione delle performance produttive, mantenendo gli effetti positivi sulla qualità della carne. In proposito, su 24 tori di razza Pezzata Rossa, lo studio ha valutato l’effetto della castrazione a 10 o 12 mesi (Anticipata vs. Tardiva; periodo di ingrasso: 191 vs. 151 giorni) sulle caratteristiche qualitative della carcassa e del Longissimus thoracis. Sulla carne sono state analizzate composizione chimica, colore, tenerezza e gusto, con tecniche strumentali e sensoriali. La castrazione anticipata comporta l’ottenimento di carne a più elevato tenore lipidico che migliora la tenerezza, aumenta la luminosità e riduce le perdite di cottura. Nel caso degli animali castrati tardivamente, la minor marezzatura sembra invece favorire la produzione di carne con un più elevato valore dell’indice del rosso e dal gusto più apprezzato alla valutazione sensoriale. In conclusione, in riferimento alle preferenze del consumatore medio italiano, i dati suggeriscono di posticipare la castrazione soprattutto per limitare una eccessiva deposizione lipidica intramuscolare.

Effect of dietary fat level on carcass traits and flesh quality of European Sea Bass (Dicentrarchus labrax) from mariculture

Abstract The study aimed at evaluating the effect of the reduction of dietary fat on juvenile European sea bass nutritional value and quality traits. Fish were reared in floating cages (Trieste Gulf, Italy) from July (11) to October (10). Two isoproteic diets were compared: LF (low fat, EE = 19.4%) vs. HF (high fat, EE = 24.6%). No significantly different growth performance was observed. LF diet-fed fish were characterized by the reduction of celomatic fat (not edible fraction) and by the increase in dressing percentage. The tested dietary fat level also affected both fillet and epiaxial white muscle proximate composition, resulting in a significantly lower fillet lipid concentration in LF diet-fed fish. Dietary treatment influenced cooked fillet colour and texture probably as a consequence of the different intramuscular fat deposition. Fillet from HF-fed fish, in fact, presented higher lightness (L*) value and lower instrumental strengthness.