STUDIO SU MODELLO FISICO DEL PROCESSO DI TRASMISSIONE DI MOTO ONDOSO A TERGO DI BARRIERE SOMMERSE CARATTERIZZATE DA DIFFERENTI LARGHEZZE DELLA CRESTA

Sommario Con il termine '' barriere frangiflutti '' viene generalmente indicato nell’ambito dell’Ingegneria Costiera un insieme di opere di difesa opportunamente create per la salvaguardia dei litorali differenti per forma, materiali utilizzati, dimensioni, e loro posizionamento. L’ambiente costiero è infatti un sistema altamente dinamico, interessato da fenomeni erosivi dipendenti da diversi fattori quali i moti ondosi, le correnti, e le maree che combinati con un’attività antropica spesso incontrollata, generano fenomeni erosivi delle nostre spiagge determinandone il loro arretramento. La necessità di risolvere questo problema ha portato nella seconda metà del ‘900 all’utilizzo per il controllo dei fenomeni erosivi di scogliere emergenti: la maggior parte delle opere di protezione dall’erosione costiera nelle coste italiane sono realizzate con scogliere emerse e in alcuni casi l’estensione delle opere raggiunge un rapporto 2.5 ad 1 con la lunghezza del litorale protetto, spesso in conseguenza di successivi interventi di emergenza e in mancanza di un piano organico. In questo caso le opere garantiscono l’obiettivo di proteggere il litorale ma possono generare vari tipi di impatto quali ridurre la fruibilità della spiaggia, peggiorare la qualità dell’acqua, generare pericoli per la balneazione , ostacolare l’utilizzo anche di piccoli natanti per il salvataggio ed alterare il paesaggio. Il fenomeno è affiancato negli ultimi 30 anni da una progressiva sostituzione di questa tipologia di opere con scogliere sommerse o poco affioranti dal mare, dunque tracimabili dall'evento ondoso, con un impatto ambientale minore dal punto di vista visivo, capaci di ridurre l’energia del moto ondoso incidente, in parte riflettendola verso il largo ed in parte dissipandola; in questo modo l’onda trasmessa dietro le strutture risulta indebolita diminuendo così il suo potere erosivo sulla spiaggia. Le barriere frangiflutti nelle diverse tipologie attualmente utilizzate sono strutture di forma trapezoidale costituite da massi di forma e dimensioni variabili, diversamente posizionate in base alle diverse dinamiche marine presenti nei siti d’interesse con le funzioni di spostare la zona di frangimento verso il largo, riducendo così l’energia dei treni d’onda diretti verso la costa, e di inibire il trasporto solido della sabbia verso il mare aperto stabilizzando quindi le sabbie nei litorali, salvaguardando tra l’altro eventuali rinascimenti presenti. L’utilizzo di barriere emerse, se da un lato fornisce una protezione quasi totale della spiaggia comportandosi come un muro poco permeabile, dall’altro genera una forte riflessione dell’onda incidente su di esse causando, a volte, un profondo scavo al piede della barriera e mettendo in pericolo la stabilità della stessa; inoltre possono contribuire a far assumere alla zona protetta caratteristiche di zone semi-lagunari con i conseguenti problemi. Le barriere a cresta bassa realizzabili tra l’altro con costi minori, nei limiti del possibile, non attenuano le onde minori che non hanno effetti distruttivi sulla spiaggia e contribuiscono alla pulizia del litorale mantenendo le dinamiche tipiche di un ambiente costiero ed evitando inoltre la formazione di sacche di calma, in cui talvolta si deposita anche ciò che non è desiderato. La riqualificazione dei sistemi di protezione è pertanto un tema attuale e di crescente interesse, e dovrebbe essere raggiunta riducendo l’impatto ambientale con il vincolo di mantenere un livello di protezione adeguato. Da questo punto di vista la conversione da scogliere emerse nella variante sommersa è una tipologia di intervento attuabile in aree protette e sebbene l’uso di tali strutture attiri un crescente interesse nella progettazione di interventi di protezione dettato dalla necessità di operare un’azione selettiva tra l’acqua e le sabbie, occorre evidenziare che la loro configurazione, in alcuni casi, può causare problemi di erosione degli arenili in quanto induce la modifica della circolazione idrodinamica nella zona compresa tra le strutture e la linea di riva. La necessità di attenuare tali effetti indesiderati ha fatto sì che l’indagine sperimentale su barriere frangiflutti tracimabili diventasse tema portante dell’Ingegneria Costiera, infatti, nonostante il largo uso che viene fatto di queste opere, non ne è ancora conosciuto completamente il comportamento idraulico in quanto sono quasi assenti misure di campo e ci si affida a formule sperimentali ed analisi condotte su modelli di laboratorio. Se da un punto di vista prettamente ambientale la riconversione di scogliere emerse in scogliere sommerse risulta un intervento auspicabile, uno degli aspetti negativi è l’incremento della trasmissione del moto ondoso, inconveniente che potrebbe essere risolto a patto di incrementare la larghezza di berma e raggiungendo in questo modo livelli di trasmissione e protezione tipici di barriera emerse. A fini progettuali sarebbe quindi molto importante poter calcolare, la larghezza di berma e la sommergenza ottimale della barriera per un fissato livello di trasmissione desiderato, sia per la conversione delle attuali opere emerse esistenti che per eventuali nuove realizzazioni. L’obiettivo del presente lavoro di tesi è l’analisi, mediante un’indagine sperimentale, diretta ad indagare l’effetto di variazioni della larghezza di cresta sulla trasmissione di moto ondoso attraverso scogliere sommerse. Gli esperimenti sono stati condotti nel canale del Laboratorio Costiero del Dipartimento di Ingegneria Civile di Firenze, e consistono in due sessioni di prove con progressivi decrementi della larghezza di cresta, per barriere sommerse, condotte con sette diversi attacchi ondosi irregolari su fondo fisso. Le equazioni esistenti per prevedere il coefficiente di trasmissione attraverso scogliere a cresta bassa si basano su dati sperimentali che riguardano prevalentemente strutture a cresta stretta e quindi l’affidabilità del calcolo della trasmissione nel caso di opere a cresta larga necessita di ulteriori verifiche. Nel primo capitolo d’introduzione, sono presentati i fenomeni oggetti di studio con una breve esposizione dello stato dell’arte ed alcune considerazioni sull’impatto ambientale di strutture artificiali in ambiente costiero. Nel Capitolo 2 è descritto l’apparato strumentale utilizzato per eseguire la parte sperimentale della tesi. Nel Capitolo 3 viene descritta la fase progettuale degli esperimenti, quindi i moti ondosi utilizzati e le barriere analizzate nelle due sessioni sperimentali. Nel Capitolo 4 sono descritti gli esperimenti condotti in canale in assenza e in presenza delle strutture sottoposte ad attacchi ondosi di diversa intensità, ivi compresa l’organizzazione e gestione dei dati acquisiti. Nel Capitolo 6 i dati acquisiti sono stati utilizzati per compiere un’analisi sulla trasmissione del moto ondoso; nel presente capitolo viene riportato il confronto tra le misure sperimentali ed il coefficiente di Trasmissione Kt calcolato secondo le formule di Van der Meer ( 1990 ), Van der Meer and Daemen ( 1994 ), D’Angremond et al. ( 1996 ), Calabrese et al. ( 2002 ) e Van der Meer et al. ( 2005 ), al variare della larghezza di cresta. Le formule sono state utilizzate all’interno del range di applicazione proposto dagli autori. Le conclusioni del presente lavoro sono esposte nel Capitolo 6

Effects of increased space allowance on animal welfare, meat and ham quality of heavy pigs slaughtered at 160Kg

Sixty barrows (Body Weight-BW- range: 23.9-160 kg) were allotted to two experimental groups (6 pens of 5 pigs each): the control group was kept at a space allowance of 1m2/head; the second group was kept at 1.3m2/head. Behaviour, growth parameters, carcass and meat quality were assessed, as well as fat and cured ham quality. Results showed that pigs raised at 1.3m2/head spent more time laying (particularly in lateral recumbency, P<0.01 and P<0.001, respectively) compared to pigs kept at lower space allowance. They also reduced the aimless exploration of the slatted pen floor (P<0.001) and increased overall expression of other, mainly active, behaviors (e.g., drinking, walking and standing, P<0.01). Pigs raised at 1.3m2/head showed higher final BW (P = 0.02), more favourable Average Daily Gain (ADG) and gain-to-Feed ratio (G:F) both during the last period of the trial (P<0.05 for both parameters) and over the entire trial (P = 0.01 for both parameters). No significant difference was observed between groups for carcass traits and the main meat quality attributes. Subcutaneous fat from green hams had higher \u3b1-linolenic acid content (P<0.01) in the group reared at greater space allowance. Green hams from this group lost less weight at trimming (P<0.01) and the resulting cured hams received better sensory evaluations (P<0.05). No difference was observed in fatty acid composition and unsaturation levels of the subcutaneous fat from cured hams. Our data suggest that heavy pigs intended for Parma ham would benefit from the adoption of higher individual floor space allowances, both in terms of animal welfare (increased possibility to rest) and of productive parameters, without having any detrimental effect on the suitability of the thighs for dry-curing or on the quality of the final product

Literature Review on the Pre-Slaughter Welfare of Italian Heavy Pigs

This work provides a narrative review of the available information on the welfare of Italian heavy pigs in the pre-slaughter phase (transport, lairage, and stunning). The meat from these pigs is used for specific PDO (Protected Designation of Origin) products, and the production rules for these specialties require higher body weight (160–170 kg) and age (in general more than 9 months) at slaughter than in most other countries. This may lead to specific behavioral and physiological needs of pigs. The present paper summarizes the main research findings and knowledge gaps for each of the pre-slaughter phases. Studies are presented according to the four principles of the Welfare Quality assessment protocol (good feeding, good housing, good health, and appropriate behavior). The results of the literature review indicate a lack of knowledge on several aspects. Most of studies were carried out in a single slaughterhouse, making it difficult to identify risk factors and confounding effects. Moreover, animal-based measures were assessed using different protocols, reducing the possibility of comparison across studies. These findings may serve as a basis for the development of specific research studies and policies aimed at enhancing the animal welfare level and the ethical attributes of this renowned production, also in accordance with consumers’ expectations

The effects of clinoptilolite on piglet and heavy pig production

To evaluate the effects of clinoptilolite on piglet and heavy pig production two separated trials have been performed. In the first trial 40 pigs of the initial body weight of 55 kg were used. Animals were homogeneously allocated to two groups: a control group traditionally fed and a clinoptilolite group in which feed contained the additive at 2%. Pigs were slaugh- tered at about 160 kg body weight. Blood samples were taken to determine blood urea nitrogen (BUN). In the second trial a total of 116 piglets from 12 litters was used. Six litters were fed from the 7th day of life a diet containing clinoptilolite at 2%. According to the dietary treatment of the suckling period, 84 weaned piglets were homogeneously allocated to two groups fed up to 33 kg body weight a diet containing or not clinoptilolite at 2%. In both trials daily weight gain, feed intake and pigs' health were regularly recorded. The dietary inclusion of clinoptilolite at 2% did not resulted in any modification either of growing performances or of uraemia. Piglets on clinoptilolite diet showed a significant (P<0.05) improvement of faecal dry matter content. At slaughtering the dietary inclusion of clinoptilolite resulted in a trend towards an improvement of lean cuts yield and in a significant increase (P<0.05) of the ratio between lean and fat cuts. From our data it is sug- gested that clinoptilolite does not impair pig growing performances, determines a higher dry matter content of piglet fae- ces and improves carcass quality of heavy pigs with particular regard to lean cuts yield and lean to fat cuts ratio

Update on animal welfare perception by Italian consumers: A descriptive survey

The aim of this study was to evaluate if and how the perception of animal welfare by Italian consumers and their purchasing behavior of animal-friendly foods have evolved in recent years. The research was carried out through a survey on a representative sample of Italian consumers (n=969). Responses showed that 69% of consumers declared to pay attention to animal welfare at time of purchasing, and they mostly acquired information about animal welfare through the mass media. In accordance with previous surveys, the categories perceived as having the highest welfare level were fish and dairy cows, whereas the lowest welfare level was attributed to broilers and pigs. Compared to previous surveys, Italian consumers seem to have improved their knowledge about the legislation on animal protection and increased their interest toward animal welfare issues. However, they still find it difficult to identifyThe aim of this study was to evaluate if and how the perception of animal welfare by Italian consumers and their purchasing behavior of animal-friendly foods have evolved in recent years. The research was carried out through a survey on a representative sample of Italian consumers (n=969). Responses showed that 69% of consumers declared to pay attention to animal welfare at time of purchasing, and they mostly acquired information about animal welfare through the mass media. In accordance with previous surveys, the categories perceived as having the highest welfare level were fish and dairy cows, whereas the lowest welfare level was attributed to broilers and pigs. Compared to previous surveys, Italian consumers seem to have improved their knowledge about the legislation on animal protection and increased their interest toward animal welfare issues. However, they still find it difficult to identify animal-friendly labels, together with a lack of knowledge about non-conventional (e.g. extensive and organic) farming systems, together with a lack of knowledge about non-conventional (e.g. extensive and organic) farming system

Towards the abandonment of surgical castration in pigs: How is immunocastration perceived by Italian consumers?

Immunocastration of pigs represents an alternative method to surgical castration, being more respectful of animal welfare. However, this new technology may not be accepted by consumers due to their perception of possible risks tied to the use of the product, thus representing a concern for the production sector. The study aimed at verifying the attitude of Italian consumers towards immunocastration and to assess whether their perception can be affected by science-based information on advantages and disadvantages of immunocastration. A total of 969 consumers (divided in three groups representative of the Italian population) were contacted and asked to complete an online questionnaire. Only technical (neutral) information on immunocastration was provided to the first group; the second and the third group received information on the advantages (+) and disadvantages (-) of the technique, shown in reverse order (+/- and -/+, respectively). The level of information did not affect consumers\u2019 perception of immunocastration. Overall, immunocastration is perceived in a predominantly positive manner (54.5%), with a relatively low level of risk perception (34.2%), and a good willingness to pay more for meat deriving from immunocastrated pigs (+18.7%)

Health risk perception, consumption intention, and willingness to pay for pig products obtained by immunocastration

Surgical castration without the use of anaesthesia and/or analgesia is considered to be detrimental for the welfare of pigs and for this reason its abandonment is advocated. Immunocastration is a more welfare-friendly alternative method; however, stakeholders in the pork sector fear consumer rejection due to perceived safety issues of immunocastrated meat. This work aimed to analyse whether Italian consumers perceive a health risk arising from the use of this technique and, if so, how the perceived risk may influence the purchase choices and the willingness to pay for products derived from immunocastrated animals. To achieve this objective, a survey was carried out on a representative sample of the Italian population. The results highlight that consumers perceive different levels of risk related to the use of immunocastration and that this influences purchasing behaviour and willingness to pay. Moreover, it should be noted that the willingness to pay is also influenced by certain demographic factors, since this is positively associated with younger respondents with lower incomes and less knowledge of farming systems, who live in rural areas and have a greater sensitivity to animal welfare. Given the concerns expressed by consumers, particular attention must be paid to the information transmitted if this technology will be widely implemented in pig husbandry

Influence of Increased Freedom of Movement on Welfare and Egg Laying Pattern of Hens Kept in Aviaries

This work investigates the effects of structural modifications on the welfare level and laying patterns of hens in a three-tier commercial aviary system. Four experimental groups were used: C (control, housed in a traditional aviary); LM (longitudinal movement, in which internal partitions were removed); VM (vertical movement, in which ramps were installed); and FM (freedom of movement, both LM and VM modifications). Hens showed worse body condition scores (p &lt; 0.05) in all the modified aviaries, while plumage condition was improved in FM but worsened in VM (p &lt; 0.05). No significant effect was observed on egg deposition patterns, egg quality or keel bone damage. When ramps were available (VM and FM groups), hens reduced the number of flights and increased the number of walks from 0.52 to 7.7% of the displacements on average (p &lt; 0.05). Apart from some feather pecking concerns in VM (likely due to overcrowding in some favourite aviary areas), LM and FM seemed to facilitate animal movement and promote species–specific behaviour. It is concluded that hen welfare in aviary systems can be improved by means of tailored structural modifications. Producers may therefore adopt some of these modifications (providing ramps and/or removing vertical barriers) to enhance the welfare of hens

Identification of Possible Pre-Slaughter Indicators to Predict Stress and Meat Quality: A Study on Heavy Pigs

This study aimed at identifying possible pre-slaughter indicators and/or indexes to be used to predict pig stress response and meat quality variation. Data were collected on 44 shipments (loads) of Italian heavy pigs. For each shipment, several pre-slaughter parameters were recorded on farm, during transport, and at the slaughterhouse. Blood and meat samples were taken from 10 pigs from every of the 44 loads included in the study (N = 440). Blood samples were used to assess cortisol and creatine kinase levels, whereas meat samples were used to assess meat quality (pH, instrumental color, tenderness, water-holding capacity, and sensory analysis). Cluster analysis of blood parameters allowed the categorization of the shipments into two main clusters: Lower Stress (LS) and Higher Stress (HS). The variables/indexes statistically differing between the two clusters were: average vehicle speed during transport, welfare index at slaughter (i.e., \u201cslaughter score\u201d), overall transport and slaughter welfare index (TSWI), distance travelled, and behaviors (slips, falls, overlaps) during unloading, which appeared to be the best descriptors of the welfare conditions experienced by Italian heavy pigs during pre-slaughter handling. No consistent effects of the stress level experienced on meat quality was detected, which warrants the need for further studies conducted under more variable pre-slaughter conditions, with the aim of simplifying and improving the TSWI