Adolfo Corato

Effect of the partial replacement of fish meal and oil by vegetable products on performance and quality traits of juvenile shi drum (Umbrina cirrosa L.)

Abstract A four-month growth trial was carried out in order to evaluate performance and quality traits of juvenile shi drum fed with two isonitrogenous and isoenergetic diets having different amounts of vegetable products (Vegetable diet vs. Control diet). Compared to the Control diet, the Vegetable diet was formulated by increasing the replacement of fish meal (14%) with soybean and cereal products, and fish oil (12%) with a mixture of vegetable oil. On June, 4 groups of 225 fish (2 replicates per dietary treatment) were sorted according to live weight and reared in fibreglass tanks over a four- month long experimental period. Fish were hand fed to apparent satiety. Offered feed, growth parameters and feed efficiency were recorded as productive performance. At the end of the trial (October) biometric, chemical and reological traits were examined to assess fish quality. The dietary treatments showed similar productive performance. The relatively high inclusion of vegetable sources led to a significant modification of body shape, mesenteric fat and viscera weight. Among quality traits, Vegetable diet-fed fish demonstrated a significantly lower whole body and fillet crude protein content. Yellowness value of the cooked fillet was significantly lower in the Control diet-fed fish, whereas fillet texture was similar. The results of this research showed that shi drum is a suitable candidate for Mediterranean marine aquaculture and its dietary formulation might include at least the amount of vegetable sources used in this trial.

Differential biohydrogenation and isomerization of [U-13C]Oleic and [1-13C]Oleic acids by mixed ruminal microbes

The additional mass associated with 13C in metabolic tracers may interfere with their metabolism. The comparative isomerization and biohydrogenation of oleic, [1-13C]oleic, and [U-13C]oleic acids by mixed ruminal microbes was used to evaluate this effect. The percent of stearic, cis-14 and- 15, and trans-9 to-16 18∶1 originating from oleic acid was decreased for [U-13C]oleic acid compared with [1-13C]oleic acid. Conversely, microbial utilization of [U-13C]oleic acid resulted in more of the 13C label in cis-9 18∶1 compared with [1-13C]oleic acid (53.7 vs. 40.1%). The isomerization and biohydrogenation of oleic acid by ruminal microbes is affected by the mass of the labeled tracer.

Effects of extruded corn on milk yield and composition and blood parameters in lactating dairy cows

Abstract According to a 2x2 cross over design, fourteen Holstein dairy cows at 99±55 DIM were fed two diets containing 21.5% DM of either ground corn (GC) or extruded corn (EC). Performance and metabolic profile were detected during the third week of each experimental period. DMI and milk yield were not affected by dietary treatments. Milk fat and protein percentage of EC diet were significantly (P<0.10) lower than those of GC diet. Probably the higher rumen degradability of starch from EC thesis modified the synthesis of specific fatty acids leading to a milk fat depression event. Diets did not influence blood parameters, except for lower values of total protein and glucose content in EC diet-fed cows. Results suggested that the dietary inclusion of extruded corn should not be used at the tested level of substitution.

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.