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RESUMEN La pulpa cítrica deshidratada (PCD), es un subproducto altamente energético con potencial para substituir los granos de cereales para la alimentación de animales domésticos. Treinta y dos corderos machos castrados, cruza Santa Inés × Texel fueron empleados con el objetivo de evaluar el efecto de la substitución del maíz por PCD sobre el desempeño productivo y características de los componentes no carcasa. La inclusión de PCD en la ración en proporciones de 0; 20; 40 y 60% de sustitución del maíz en base seca constituyeron los cuatro tratamientos 0PCD, 14PCD, 29PCD y 43PCD. El delineamiento utilizado fue el de bloques completos al azar con cuatro repeticiones. Los datos fueron sometidos a ANAVA y las medias comparadas por el test de Duncan (p0.05) in the other components of GIT, in total fat and in the net weights of the different vital organs.

The citrus industry produces a wide amount of citrus pulp which can represent an alternative feed resource for feeding ruminants. However, citrus pulp also contains chemicals such as polyphenols, which can cause toxicity, limiting its use. We investigated the potential of replacing barley by dehydrated citrus pulp (DCP), at two levels of inclusion (24% and 35% on an as-fed basis), in a lamb fattening diet and monitored the performance, feeding pattern and serum parameters of the experimental lambs. The consumption of a diet containing up to 35% of DCP resulted in equivalent performance, feed efficiency and carcass weight and yield as compared with animals ingesting a cereal-based diet (control). The daily feed consumption pattern was slightly affected by the inclusion of citrus pulp in the diet. In terms of serum haematochemical profile, DCP ingesting animals had similar levels to control lambs. Pertaining to the serum protein profile, DCP addition had minor effects. A significant increase in the albumin content and in the albumin to globulin ratio was observed in the animals ingesting 35% DCP compared with the control-fed ones; but the values were not at a level to cause metabolic distress. The use of high levels of DCP in small ruminant fattening can ensure equivalent animal performances and metabolic welfare while providing a value addition to a local by-product.

Tese de Doutoramento em Ciências Veterinárias, especialidade de Produção Animal alexandrafrancisco@sapo.pt Ruminant meats are characterized by being rich in saturated fatty acids (SFA), particularly, and low in polyunsaturated fatty acids (PUFA), which is regarded as disadvantageous for humans. However, ruminant meats are also the dietary source of some bioactive health benefit fatty acids, including conjugated linoleic acid isomers (CLA) and long chain polyunsaturated fatty acids from the n-3 series (n-3 LC-PUFA). In the present thesis we have explored three nutritional strategies to improve the fatty acid (FA) profile of lamb meat, in order to maximize CLA and n-3 LC-PUFA content. Two experiments were conducted to evaluate the effects on lipid metabolism and fatty composition of meat from lambs intensively fattened of the i) dietary inclusion of Cistus ladanifer L. (C. ladanifer); ii) dietary supplementation with vegetable oils and iii) replacement of cereal grains by dehydrated citrus pulp (DCP) in diets. A global evaluation of the effects of the dietary treatments on production, meat quality and meat lipid composition, was achieved by recording the productive performance of lambs, carcasses composition, and determining analytically the fatty acid composition, oxidative stability and organoleptic quality of meat. Moreover, the expression of genes encoding Δ5-, Δ6- and Δ9-desaturases (FADS1, FADS2 and SCD) in longissimus muscle was also assessed. The first experiment, involved 54 Merino Branco lambs, and evaluated the effects of the dietary inclusion of C. ladanifer (rockrose) (Cistus) and of the lipid supplementation with a blend of linseed and soybean oil (2:1 vol/vol). Nine diets were formulated resulting from the combination between 3 levels of C. ladanifer inclusion (50, 100 and 200g/kg of dry matter (DM)) and 3 levels of oil supplementation ((0, 40 e 80g/kg DM)). On second experiment, 32 Merino Branco lambs were fed using diets containing 60g/kg DM of soybean oil and 50% of dehydrated lucerne, and there were evaluated the effects of C. ladanifer inclusion (0 vs 150g/kg) DM) and the replacement of cereal grains by DCP in the diets. On the first experiment, the diets did not affect animal´s growth. Lipid suplementation reduced DM intake, muscle proportion in the carcass and increased kidney knobb channel fat. Meat chemical and physical parameters were not influenced by the diets. The level of 100g/kg of C. ladanifer inclusion improved meat oxidative stability during 7 days of storage. The perception of off-flavours was higher and meat overall acceptability by the sensory panel was reduced with suplementation 8% oil blend. The increasing inclusion of C. ladanifer and oil in the diet act sinergetically on the 10t-18:1 in meat. C. ladanifer increased total amount and proportion of trans monoinsaturated FA (trans MUFA) and reduced the proportions of eicosapentaenoic (EPA) and docosapentaenoic (DPA) acids. The dietary suplementation with vegetable oil blend was a good strategy to improve nutritional value of meat, enhancing total amount of linolenic acid (18:3 n-3) and of n-3 PUFA, and reducing the proportion of SFA, which it was followed by an increment of the proportion of PUFA on lipid profile of intramuscular fat (IMF). The expression of the SCD mRNA increased with C. ladanifer but it was not correlated with the concentration of the Δ9-desaturase FA products. On the second experiment, DM intake increased with C. ladanifer, althought growth was not influenced by diets. Carcass composition was not affected by the dietary treatments, but an interaction between C. ladanifer and DCP was observed for dressing percentage. Dietary factors did not influence muscular pH, cooking losses, meat color and oxidative stability during storage. However, meat shear force increased with the adition of C. ladanifer to diets. Meat tenderness and juiciness were both reduced by C. ladanifer and DCP, but only C. ladanifer reduced meat overall acceptability assessed by the sensory panel. The inclusion of C. ladanifer to 1:1 forage to concentrate ratio diets enriched with soybean oil, reduced the occurrence of trans-10 shift, but did not increase 11t-18:1 and 9c,11t-18:2 concentrations on meat lipids. Trans fatty acids (TFA) were reduced by C. ladanifer inclusion in diets. Dehydrated citrus pulp improved meat nutritional value by increasing 18:3 n-3. RESUMO - Enriquecimento em ácidos gordos bioactivos da carne de borrego de sistema intensivo através da modulação nutricional do metabolismo lipídico - A carne de ruminantes caracteriza-se por ser particularmente rica em ácidos gordos saturados (AGS) e pobre em ácidos gordos poliinsaturados (AGPI), o que é considerado como negativo para a dieta humana. Contudo, é também uma importante fonte de alguns ácidos gordos bioactivos benéficos para a saúde, como os isómeros conjugados do ácido linoleico (CLA) e ácidos gordos poliinsaturados de cadeia longa da família n-3 (n-3 CL-AGPI). Na presente tese explorámos três estratégias nutricionais de modo a melhorar o perfil lipídico da carne de borrego através do aumento do seu conteúdo em CLA e em n-3 n-3 CL-AGPI. Foram realizadas duas experiências nas quais os efeitos i) da inclusão de Cistus ladanifer L. (esteva); ii) da suplementação lipídica com óleos vegetais e iii) da substituição dos grãos de cereais por polpa de citrínos desidratada (PCD) no metabolismo lipídico e na composição em ácidos gordos da carne de borrego de sistema intensivo de engorda foram avaliados. A avaliação integrada dos efeitos dos tratamentos no desempenho produtivo, foi efectuada registando-se a ingestão de matéria seca (MS), ganho médio diário e composição das carcaças dos borregos, assim como a qualidade física e sensorial da carne e a sua composição em ácidos gordos e níveis de expressão dos genes que codificam para as Δ5, Δ6 e Δ9-desaturases (FADS1, FADS2 e SCD mRNAs). No primeiro ensaio, que envolveu 54 borregos Merino Branco avaliámos a inclusão, na dieta, de Cistus ladanifer (esteva), e da suplementação lipídica constituída por uma mistura de óleo de linho e de soja (2:1 vol/vol). Para tal foram formuladas 9 dietas que resultaram da combinação entre 3 níveis de inclusão de C. ladanifer (50, 100 e 200g/kg de matéria seca (MS)) e 3 níveis de suplementação lipídica (0, 40 e 80g/kg de MS). No segundo ensaio, utilizaram-se 32 borregos alimentados com dietas contendo 50% de luzerna desidratada e 60g/kg MS de óleo de soja, e avaliaram-se os efeitos da inclusão de C. ladanifer (0 vs 150g/kg) de MS) e da substituição dos grãos de cereais por polpa de citrínos desidratada (PCD) nas dietas. No primeiro ensaio, os tratamentos não afectaram o crescimento dos animais. O óleo reduziu a ingestão de MS, a proporção de músculo da carcaça e aumentou a quantidade de gordura pélvica e renal. As caraterísticas físicas e químicas da carne não foram afectadas pelas dietas. O nível de 100g/kg de esteva melhorou a estabilidade oxidativa da carne durante o armazenamento de 7 dias. A percepção de off-flavours foi superior e a aceitação global por parte do painel de provadores foi inferior para a suplementação com 8% de óleo. A inclusão de C. ladanifer potenciou o aumento de 10t-18:1 na carne induzido pelo óleo. Com a inclusão de C. ladanifer nas dietas aumentou a quantidade total e proporção de ácidos gordos monoinsaturados trans (TransAGMI) e diminuiram as proporções dos ácidos eicosapentaenoico (EPA) e docosapentaenoico (DPA). A suplementação das dietas com a mistura de óleos vegetais foi uma boa estratégia para melhorar o valor nutricional da carne, permitindo um aumento da quantidade total de ácido linolénico (18:3 n-3) e n-3 AGPI, e a redução da proporção de AGS acompanhada de um aumento da proporção de AGPI no perfil lipídico da gordura intramuscular. A expressão do mRNA do gene SCD aumentou com a inclusão de C. ladanifer nas dietas. No segundo ensaio, a ingestão de MS aumentou com a inclusão de C. ladanifer, embora o crescimento não tenha sido influenciado pelas dietas. A composição da carcaça não foi afectada pelos tratamentos, mas verificou-se uma interacção entre a inclusão de esteva e a de PCD que afectou o rendimento da carcaça. Os factores em estudo não influenciaram o pH muscular, as perdas por cozedura, a cor da carne e a sua estabilidade oxidativa. No entanto, ocorreu um aumento da força de corte da carne com a adição de C. ladanifer às dietas. A tenrura e a suculência da carne sofreram uma diminuição com a inclusão de C. ladanifer e de PCD nas dietas, no entanto a aceitação global da carne pelo painel de provadores apenas foi diminuída com C. ladanifer. A inclusão de C. ladanifer a dietas com uma relação de forragem: concentrado de 1:1 e enriquecidas com óleo de soja, reduziu a ocorrência do trans-10 shift, embora não tenha aumentado os teores de 11t-18:1 e de 9c,11t-18:2 na fracção lipídica da carne. O total de ácidos gordos trans (AGT) na carne foi reduzido pela inclusão de esteva nas dietas. A PCD melhorou o valor nutricional da gordura da carne de borrego, aumentando a concentração em 18:3 n-3.

A study was designed to determine the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly-received English × Continental heifers. Heifers (n=180) were sourced in two loads (188.7 ±18.0 kg and 225.2 ± 22.2 kg, respectively) from commercial auction barns and placed on trial at the Texas Tech University Beef Center in New Deal, Texas. A completely randomized block design was utilized with BW nested within arrival load and blocked by BW. Three dietary treatments were fed (36 pens; 5 heifers/pen; 12 blocks; 3 pens/block; 12 pens/treatment). Treatment diets were formulated to contain: 1) 0%; 2) 10%; or 3) 20% DCP on a DM basis. Diets containing DCP were formulated to be exchanged with steam flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the entire 56-d trial period, as the amount of dietary DCP increased DMI decreased (P = 0.02; 6.70, 6.13, and 5.96 kg, for 0, 10, and 20% DCP, respectively), ADG decreased (P < 0.0001; 1.88, 1.27, and 1.00, respectively), and G: F decreased (P = 0.02; 0.225, 0.210, 0.191, respectively). From d 0 to d 28 there was no difference in the observed, minus the expected NEg of the diet (P = 0.73), from d 28 to d 42 there was a linear increase in NEg with an increase in the percentage of DCP (P=0.003), and from d 42 to d 56 there was a linear increase in NEg favoring CON cattle over DCP cattle (P = 0.006). At the conclusion of the trial a subset of heifers (n = 24; 218.3 ± 2.4 kg) were utilized to evaluate the physiological and acute phase responses (APR) to an endotoxin (lipopolysaccharide; LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were challenged i.v. with LPS (0.5 µg/kg BW), and blood samples were collected every 0.5 h from -2 to 8 and again at 24 h relative to LPS challenge (0h). Sickness behavior scores (SBS) were assigned following collection of each blood sample. Serum was analyzed for cortisol, interleukin-6 (IL-6), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) concentrations as well as serum glucose, blood urea nitrogen (BUN), and non-esterified fatty acid (NEFA) concentrations. Post-LPS SBS increased (P < 0.01) and were greater in 10% DCP than 20% DCP and CON. Heifer BW was measured at cannulation, and 24 and 72-h ) post-LPS. BUN levels showed a treatment effect pre-LPS favoring CON cattle (P < 0.01). Post-LPS glucose, NEFA, and BUN concentrations were greater in CON cattle (P < 0.01) cortisol concentrations were greatest in 10% DCP heifers than CON and 20% DCP treatments ( P < 0.01). IFN-γ, TNF-α, and IL-6 increased post-LPS (P < 0.01) and were greater in 20% DCP over 10% DCP and CON treatments ( P < 0.01). These data indicate that dietary DCP can modulate both the physiological and APR of newly-received heifers to an endotoxin challenge, and it effects feedlot performance variables.