INFLUENZA DEL REGIME ALIMENTARE SULLE CARATTERISTICHE DIETETICO-NUTRIZIONALI DEL LATTE DI CAPRA

Il progressivo aumento della domanda da parte del consumatore di derrate alimentari in grado di apportare oltre ai classici nutrienti, anche molecole cosiddette “bioattive” che possono esercitare un ruolo favorevole sul mantenimento dello stato di salute e sulla prevenzione delle malattie dell’uomo. Negli ultimi decenni, numerosi gruppi di ricerca hanno effettuato sperimentazioni, nel comparto lattiero-caseario, volte a chiarire il ruolo dei lipidi di origine animale nella induzione/prevenzione di quelle patologie legate alla cattiva alimentazione e/o a scorretti stili di vita, quali la sindrome metabolica (SM), il cancro al colon, le malattie cardio-vascolari (CHD), l’aterosclerosi e l’obesità anche infantile. Tra le componenti funzionali della frazione lipidica del latte, di sicuro interesse sono gli isomeri dell’acido linoleico coniugato, detti CLA. Tra questi risulta predominante l'acido rumenico (RA: cis-9, trans-11 CLA) che possiede spiccate attività contro il cancro e l'aterosclerosi. La presenza esclusiva dell’acido rumenico delle derrate alimentari derivanti dai ruminanti è legata sia alla bioidrogenazione in sede ruminale di alcuni acidi grassi insaturi (acido linoleico: C18:2 omega-6; acido linolenico: C18:3 omega-3) ingeriti dall’animale sia dalla sintesi endogena ad opera Δ9-desaturasi mammaria a partire dall’acido vaccenico (VA: trans-11 18:1 CLA). Nella prima indagine, infatti, nella quale si è voluto verificare se la supplementazione con olio di palma idrogenato alla dieta di soggetti allevati con sistema stallino, comportasse un miglioramento delle caratteristiche nutrizionali del latte, le concentrazioni di acidi grassi a catena corta e media, nonché dei C14: 0, C16: 1 cis-9 e del cis-9 trans-11 CLA sono risultate significativamente maggiori nella derrata fornita dagli animali che ricevevano tale aggiunta alla razione. In merito alle concentrazioni di CLA nel latte, è emerso anche che l’espressione del gene che codifica per l’SCD, enzima coinvolto a livello tissutale nella loro produzione, non risulta omogenea durante la lattazione. I nostri risultati, inoltre, in apparente contrasto con quanto riportato in letteratura, nonostante un aumento del colesterolo ematico, non indicano una influenza negativa sul metabolismo, derivanti dall’aggiunta di grassi. L’impiego di 50g/capo/die di olio di palma idrogenato è stato ben tollerato dagli animali e può rappresentare un utile strumento per aumentare la disponibilità di energia in periodi di bilancio energetico negativo. Nella seconda sperimentazione, è stato confermato che l’impiego del pascolo determina la produzione di latte il cui profilo acidico si caratterizza per elevati contenuti in acidi grassi poliinsaturi delle serie omega 3 nonchè per contenuti significativamente maggiori di CLA. Alla luce della acclarata influenza che entrambi questi parametri esercitano sulla salute umana, è possibile esprimere un giudizio nettamente favorevole sull’adozione di sistemi di allevamento che prevedano il ricorso al pascolo. Notevole è apparsa, l’influenza dello stadio vegetativo e quindi della presenza di precursori nell’erba ingerita sul profilo acidico del latte, mentre l’espressione del gene che codifica per l’ SCD è parso essere regolato soltanto dalla presenza di acido linoleico nella dieta. Per quanto concerne, infine, i miRNA, piccoli RNA endogeni in grado di ridurre la trascrizione di mRNA nelle cellule e di regolare il metabolismo lipidico, essi sono risultati maggiormente rappresentai nel latte degli animali allevati al pascolo. In quest’ ultimo, inoltre, il miRNA 103 ha mostrato trend sovrapponibile a quello dell’espressione dell’ SCD

Aloe arborescens supplementation in cat diet: Evaluation of effects by in vitro gas production technique

The aim of the present study was to evaluate the effects of Aloe arborescens on organic matter digestibility (OMD), cumulative gas (OMCV) and short chain fatty acids (SCFA) production, using the in vitro gas production technique (IVGPT). Three adult cats were fed with a commercial diet (CP 31.21; EE 16.64% as fed) for 20 days before the collection of their faeces used as inoculum. The same diet, used as substrate, was incubated in vitro supplemented with different amounts (0, 0.7, 1.6 and 3.2%) of lyophilised Aloe arborescens. OMD, OMCV and SCFA significantly decreased with the increase of Aloe addition; an increase of L-lactic acid production was detected, even if pH was within physiological range. A potential prebiotic role of the Aloe arborescens car- bohydrates was hypothesised in cats, but it needs further investigations. As a whole, our results show that IVGPT can represent a useful tool for nutritional evaluation of novel ingredient and/or additive also in cats

In vitro fermentation of structural carbohydrate-rich feeds using faecal inoculum from pigs

Seven feeds were tested in vitro using faecal inoculum from pigs. Sugar beet pulp, wheat bran, soybean hulls, grapecake, glutamic beet pulp, citrus by-product and fructo-oligo- saccharides (FOS) were fermented for 96 h. Cumulative gas production was measured as indicator of the fermentation kinetics. At the end of incubation organic matter disappearance and fermentation end-products (short-chain fatty acids and NH3) were also measured. The gas production profiles were fitted with a multi- phasic model. Significant differences were detected between grapecake and FOS: the very low gas production for the first one was probably due to the high lignin and tannins contents of this by-product, while the higher organic matter cumulative gas volume (OMCV) and organic matter disappearance (OMD) values for FOS were due to the high soluble fibre proportion. Soybean hulls and citrus by-product, showed similar values of degradability and gas production and were characterised by different fermentation profiles. Grapecake showed the lower fermentation, while citrus by-product was characterized high gas and short-chain fatty acids production. These characteristics could be particularly useful to optimize the caecum-colon fermentation in order to obtain a high butyrate acid production

Regulation of Stearoyl Coenzyme A Desaturase 1 Gene Promoter in Bovine Mammary Cells

Stearoyl-Coenzyme A desaturase 1 (SCD1) belongs to the fatty acid family of desaturases. In lactating ruminants, the SCD1 protein is highly expressed in the mammary gland and is relevant for the fatty acid composition of milk and dairy products. Bovine mammary epithelial cells (BME-UV1), cultured in vitro, have been proposed as a model to reproduce the biology of the mammary gland. The present study was designed to investigate the responsiveness of bovine SCD1 promoter to serum, insulin, oleic acid, and NFY transcription factor in BME-UV1 cells. A luciferase-based reporter assay was used to monitor the transcriptional activity of the SCD1 promoter region in BME-UV1 cells treated or not with insulin and/or oleic acid. The level of endogenous SCD1 mRNA was evaluated by Real time PCR. Insulin (20 ng/mL) induced a 2.0 to 2.5-fold increase of SCD1 promoter activity. Additionally, the effect of insulin was inhibited by oleic acid, serum components, and NFY enforced expression. Serum and NFY showed no synergistic or additive effect on SCD1 promoter activity suggesting that they repress SCD1 transcription through the same responsive element

Influence of pasture on goat milk fatty acids and Stearoyl-CoA desaturase expression in milk sommatic cells

The effect of pasture fatty acid profile along the year on the Stearoyl-CoA desaturase (SCD) expression was evaluated over 5 months using 30 pluriparous goats, delivered in February. The animals had free access to pasture constituted by 60% Leguminosae and 40% Gramineae, and received 500g/head/day of concentrate. From the second half of April, goats were milked twice a day for 5 months. Daily milk yield was recorded and, monthly, representa- tive individual milk and pasture samples were analysed for chemical composition and fatty acid profile. The SCD expression was studied by extraction of mRNA from milk somatic cells and analysed by RT-PCR. Average milk yield, fat and protein were 1420 (g/d), 4.45 (%) and 3.62 (%), respectively. Milk yield decreased along the lactation (P < 0.01) while milk fat was higher in August. Milk total CLA showed the highest levels (P < 0.01) in June and August (mg/100 g fat: 0.98 and 1.21, respectively) as consequence of the highest levels of pasture C18:2 and C18:3 in June (% of total FA: 34.1 and 42.7, respectively) and August (% of total FA: 42.7 and 46.3, respectively). The grazing season as well as lactation stage affected the SCD mRNA abundance determined from milk somatic cells with values (arbitrary units) that progressively decreased from April (1.95) until June (1.40), increased in July (1.70) and decreased again in August (0.83)