Ana Haro

Assessing the effects of severe heat treatment of milk on calcium bioavailability: In vitro and in vivo studies

Thermal processing of milk is a common practice. As milk is the main source of dietary calcium, this study aimed to assess the effects of overheating milk on calcium availability. Thus, thermally damaged milk (overheated, OH, milk; 3 cycles of sterilization at 116 °C, 16 min) was compared with UHT milk (150 °C, 6s) in 2 types of assays: in vitro and in vivo (rats). In addition, the greater Maillard reaction rate associated with thermal treatment in OH milk was confirmed by determining specific (furosine) and unspecific markers (CieLab color). A negative effect on calcium solubility was observed after in vitro digestion of OH milk compared with UHT milk. Feeding rats the diet containing OH milk as the protein source led to significantly lower values of apparent calcium absorption and retention than those found among animals fed the UHT milk diet. Whereas reducing the absorption appears to result mainly from the decreased food intake, the negative effect on retention seems to be due to factors derived from milk thermal damage, such as the formation of Maillard reaction products. It was concluded that milk-processing conditions warrant special attention to prevent impaired dietary calcium utilization. This may be especially important in situations where milk and dairy products are the main dietary components, such as in early infancy.

Ácido linoleico conjugado: interés actual en nutrición humana

El termino acido linoleico conjugado (ALC) incluye una serie de isomeros posicionales y geometricos del acido linoleico. Las principales fuentes naturales son la carne de animales rumiantes, la leche y los derivados lacteos. Ademas, existe en el mercado una amplia gama de alimentos que han sido enriquecidos en ALC (manipulacion de la dieta del animal, adicion de ALC procedente de otras fuentes naturals como el aceite de cartamo). La diferencia estriba en que, mientras el principal isomero presente de forma natural en los alimentos es el cis-9 , trans-11 , las preparaciones comerciales contienen cantidades similares de los isomeros cis-9 , trans-11 y trans-10 , cis-12 . Aunque el ALC es un componente minoritario en la dieta, en la actualidad had espertado gran interes y ha promovido una intensa investigacion acompanada de un boom publicitario debido a sus potenciales efectos sobre la salud: modificacion de la composicion corporal con reduccion de la masa grasa, propiedades antiaterogenicas, hipolipemiantes, antidiabetogenicas e inmunomoduladoras, entre otras. Estos efectos se han observado principalmente en modelos animales y cultivos celulares. Los estudios en humanos son escasos e incluso, a veces, contradictorios. En esta revision se profundiza en los trabajos de investigacion mas recientes sobre el interes nutricional del ALC. De la amplia revision realizada se deduce la necesidad de estudios adicionales en humanos que permitan obtener datos sobre las cantidades optimas de ingesta, asi como sobre los efectos tanto a corto como a largo plazo, y posibles efectos secundarios de cada isomero individual del ALC con el fin de determinar su seguridad y eficacia.

Dietary protein excess does not influence calcium and phosphorus absorption and retention in Iberian pigs growing from 50 to 100 kg body weight.

Effects of apparent total tract digestible dietary protein [expressed as apparent ileal digestible (AID) Lys in parentheses] from excessive to marginally deficient [110 (7.9), 92 (6.6), 73 (5.3) and 54 (3.8) g/kg DM] and feeding level (FL; 0.80 and 0.95 × ad libitum) upon fractional absorption and retention of Ca and P was studied in 48 purebred Iberian barrows from 50 to 100 kg BW to investigate possible detrimental effects of protein over supply on Ca and P metabolism. The diets were prepared by diluting a high-protein diet, formulated according to the ideal protein concept, with a protein-free mixture. The diets provided (per kg DM) 11.6 to 10.7 g Ca, 6.67 to 6.25 g total P, and 13.9 to 14.8 MJ ME. Intake levels with free access to feed were calculated according to individual BW and were adjusted weekly. A digestibility and balance trial was performed at 75 kg BW. The ADFI was 3104 and 2643 g for 0.95 and 0.80 × ad libitum FL. The ADG reached a maximum at 854 g (18.87 g/MJ ME intake) with the diet containing 5.3 g AID Lys/kg DM. Dietary AID Lys content did not alter Ca and P fractional apparent absorption, which attained average values of 0.417 ± 0.0109 and 0.545 ± 0.0106. The Ca and P retention as a fraction of intake remained unaffected at 0.403 ± 0.0114 and 0.403 ± 0.0120. The Ca urinary losses were not elevated by excess of dietary protein supply, remaining at 0.260 ± 0.0212 g/d. High feeding level increased (P < 0.05) the flow of absorbed Ca and P. In conclusion, long-term, high-protein (Lys) intake did not affect Ca intestinal absorption and renal excretion in the pig.

Utilization of milk fatty acids by the suckling Iberian piglets

A total of 16 pure-bred Iberian (IB) sows, all of them suckling six piglets, were used, eight of them in each of the two consecutive trials (1 and 2). Daily milk yield and composition were determined weekly over a 34-day lactation period. Within each litter, one piglet at birth and four piglets on day 35 of life were slaughtered. Milk intake per piglet tended to be greater in trial 2 (832 v. 893 g/day; P=0.066), but piglets grew at 168±3.3 g/day, irrespective of the trial. In the IB sow milk, the linoleic (LA) : linolenic (LNA) acid ratio averaged 14.6 and 15.2 in trial 1 and trial 2, respectively. A fivefold increase in piglet body fat content was observed over lactation (P<0.001). Most of this fat (81.4%) was present in the carcass. After 34 days of lactation, whole-body relative content of palmitic, palmitoleic, stearic and oleic acids were very close to those in the milk consumed, suggesting direct deposition. Daily deposition of LA derivatives and of LNA and its derivatives was found to be extremely low (<0.02 g, on average). Moreover, some of the arachidonic acid (ARA) in tissues of the IB piglet at birth disappeared throughout the lactating period. An overall fractional deposition for total fatty acids (FA) was 0.409. Fractional oxidation (disappearance) rates were 0.939 and 0.926 for n-6 and n-3 polyunsaturated FA. The overall rate of disappearance for the major non-essential FA (myristic, palmitic, palmitoleic, stearic and oleic acids), estimated as 1-the overall fractional deposition rate, was 0.546. It is concluded that the high degree of FA unsaturation, high oxidation rate of LA and LNA, and poor synthesis of ARA from LA and of docosahexaenoic acid from LNA found in the suckling piglet might increase the energy cost of whole-body fat accretion, a contributor to the observed low efficiency of use of milk energy for growth.

Evaluación nutricional de los menús servidos en las escuelas infantiles municipales de Granada

INTRODUCTION The school canteen plays today an essential role in child nutrition and for consolidating appropriate eating habits. In Spain, the guidelines for school meals have been established by the NAOS strategy and the Perseus program, and are especially aimed at school children of 6-10 years. However, there is a lack of information on menus offered in pre-school education centres, which take in children of pre-school age. The aim of this study was to evaluate the composition and the food supplied in pre-schools of the province of Granada. MATERIAL AND METHODS A study was conducted on the menus offered in public pre-schools in Granada, with a population of 420 children aged 2-6 years old. A total of 20 menus were analysed, and details were collected including direct information on the ingredients used, the proportion of these in each dish, and the form of preparation. The daily intake of energy and nutrients, as well as the frequency of weekly supply of the different food groups were studied. RESULTS The average energy content of the menus was 512.5kcal, distributed into protein (17.3%), carbohydrates (48.8%), and lipids (33.9%). A suitable supply of fibre (7.8g/day) was observed, but content of calcium and zinc did not reach recommended levels. The supply of vegetables was adequate, with a daily presence of salad, as well as vegetables, meat, fish and fruit. CONCLUSION Menus evaluated represent an adequate content of energy, and proper supply of the different groups of foods, especially vegetables, fruits and salads. A great effort is observed in the centres to adapt meals to nutritional recommendations.

Effects of protein intake on rate of growth, protein deposition, and carcass traits of heavy Iberian pigs

A feeding, digestibility, and balance trial was performed to determine the effect of the incorporation of increasing amounts of soybean protein concentrate (SPC) to a basal acorn diet at a fixed energy intake on the rate of growth, protein deposition (PD), and carcass traits of heavy Iberian (IB) pigs. Sixteen purebred IB barrows (103.9 ± 0.9 kg initial BW) were used. The pigs were individually confined and allocated to 4 groups of 4 pigs each. Whole acorns were provided with slight restriction to minimize acorn kernel (AK) remains. Water was freely available. The incorporation of SPC raised the available CP from 49.1 g/kg DM (1.91 g total Lys/kg DM) in AK up to 135 g/kg DM (7.24 g total Lys/kg DM). After 72 d of trial, the pigs achieved 134.4 ± 1.3 kg BW and were then slaughtered. Average daily BW gain increased with increasing dietary CP (linear, P < 0.001; quadratic, P < 0.01), with a plateau at dietary CP concentrations (provided by AK and SPC) beyond 72.2 and 100 g/kg DM, respectively, for which an ADG of 449 g was achieved. There was a linear and quadratic effect of dietary CP and Lys level on the apparent digestibility of CP (linear, P < 0.001; quadratic, P < 0.05) and on the efficiencies of utilization of total N (retained N/N intake; linear, P < 0.001; quadratic, P < 0.001) and N apparently absorbed (retained N/apparent digestible N; linear, P < 0.05; quadratic, P = 0.067). Protein deposition ranged between −4.59 g/d in pigs not provided with SPC to 61.4 g/d in pigs fed the greatest level of SPC inclusion. The lowest daily intake of total Lys resulting in maximum PD (69.5 g/d) at the fixed level of energy intake observed (2.36 × ME maintenance requirements) was 21.0 g. Hot carcass and cold carcass weights, but not carcass yield, increased when feeding the daily ration containing 100 g SPC and leveled off thereafter (linear, P < 0.01; quadratic, P < 0.01). An average increase of 8.3% and 8.7% was obtained, respectively. The provision of SPC had no effect on back fat thickness. Primal cuts, but not yield (except for loin), increased (sirloin: linear, P < 0.05; loin: linear, P < 0.001; quadratic, P < 0.05; ham: linear, P < 0.05) or showed a tendency to increase (butt lean: linear, P = 0.068; quadratic, P = 0.077; ribs: quadratic, P = 0.067; shoulder: quadratic, P = 0.064) with the provision of dietary protein. No effect of the level of incorporation of SPC to the diet was observed on CP, total fat, total ash, and energy contents or on relative fatty acid profile of loin and sirloin.

Portal-drained viscera heat production in pigs fed betaine and conjugated linoleic acid (CLA) supplemented diets

Betaine and CLA have the potential to alter growth and body composition in swine (Fernandez-Figares et al., 2002, 2008) improving feed efficiency, protein accretion rate and reducing body fat. Although their mode of growth promotion is not well understood. We hypothesised that differences in portal-drained viscera (PDV) heat production might partially explain differences in growth in pigs fed betaine and CLA (Fernandez-Figares et al., 2008).

Portal-drained viscera heat production in Iberian pigs fed betaine and conjugated linoleic acid supplemented diets.

BACKGROUND Betaine and conjugated linoleic acid (CLA) may alter growth and body composition in pigs, although their mode of action is not well understood. Portal-drained viscera (PDV) have a disproportionate influence with respect to their masses, and this may affect the productivity of more profitable tissues. The objective of this study was to determine if the use of betaine and/or CLA in the diet affects PDV heat production. RESULTS Postprandial portal blood flow (PBF) was greater (19.0%, P = 0.004) for control compared with the other three diets. The lowest (P < 0.001) value for postprandial PDV O2 consumption corresponded to betaine + CLA followed by betaine and CLA diets (32.7, 25.4 and 17.7% respectively with respect to control diet). Postprandial PDV heat production was greater (26.4%, P < 0.001) for control with respect to the other three diets, with the minimum value corresponding to betaine + CLA (34.1% lower than control). CONCLUSION Supplementation with betaine and/or CLA reduced the PBF, O2 consumption and therefore PDV heat production with respect to control diet. This effect was more pronounced when betaine and CLA were supplemented together, potentially increasing the energy availability for other body tissues.

Similar effects of lysine deficiency in muscle biochemical characteristics of fatty and lean piglets

The main objective of this work was to investigate the effects of feeding Lys-deficient diets on muscle biochemical characteristics, particularly intramuscular fat concentration and fatty acid profile, in a fatty (Iberian) and a conventional pig genotype (Landrace × Large White [LDW]) maintained in identical experimental conditions. Performance and plasma metabolite changes were also monitored. Twenty-eight barrows of 10 kg initial BW, 14 of Iberian and 14 of LDW breed, were randomly assigned to each of 2 experimental diets in a 2 × 2 factorial arrangement (2 breeds × 2 diets). Seven pigs were allocated to each treatment combination. Diets (isonitrogenous and isoenergetic; 200 g CP/kg DM and 14.7 MJ ME) based on barley, corn, corn gluten meal, and soybean meal, with identical composition, except for their Lys content (10.9 g/kg for the diet adequate in Lys and 5.2 g/kg for the diet deficient in Lys), were assayed. Pigs were housed in individual 2 m pens and fed at 85% of ad libitum intake of the Iberian genotype, of greater intake capacity. Daily feed allowance was based on BW individually measured each week. At 25 kg BW, pigs were slaughtered by exsanguination after electrical stunning. Blood samples were taken and longissimus dorsi and biceps femoris muscles were rapidly dissected and stored frozen prior to analysis. Performance was reduced in both pig breeds when fed Lys-deficient diets, particularly in LDW pigs (breed × diet interaction, < 0.05). Intramuscular fat content increased in longissimus dorsi of Iberian ( < 0.05) and in biceps femoris of both pig genotypes ( < 0.01) when fed Lys-deficient diets. Oleic acid increased ( < 0.05) and PUFA acid decreased ( < 0.01) in longissiumus dorsi and biceps femoris of pigs of both genotypes fed Lys-deficient diets. The proportion of oxidative fibers ( < 0.001) and free carnitine content ( < 0.05) increased in longissimus dorsi of both pigs types fed Lys-deficient diets. Plasma creatinine was greater in LDW pigs compared with Iberian pigs ( < 0.01). Urea and total cholesterol increased in pigs consuming Lys-deficient diets ( < 0.01). The plasma free carnitine concentration was higher in Iberian pigs than in LDW pigs ( < 0.059). No changes in plasma carnitine status due to dietary Lys supply were detected. Feeding Lys-deficient diets could be a suitable strategy for increasing intramuscular fat content in fatty and lean pigs.

Differences on meat colour and composition between ‘Landrace × Large White’ and ‘Iberian’ pigs under identical nutritional and management conditions

In pig production, factors such as nutritional system and genotype affect quality characteristics of meat. This study was aimed to evaluate differences in nutritional composition and colour of meat between Iberian (IB) and Landrace × Large White (LLW) pigs reared under identical nutrition and management conditions. Nutrient composition, mineral content, fatty acid profile and instrumental colour of two muscles (longissimus thoracis and biceps femoris) were examined at two growing stages (50- and 115-kg weight). Significant differences were found in relation to genotype. IB muscles contained higher amounts of intramuscular fat, dry matter, monounsaturated fatty acids, iron and zinc, and were redder (higher a* value) and with less colour saturation (lower hue angle), than those from LLW pigs. Significant relationships between colour coordinates with the mineral content and the lipid profile of muscles were found: redness was mainly linked to iron, zinc and monounsaturated fatty acids levels, whereas yellowness was positively related with copper, polyunsaturated fatty acids and linoleic acid level. The results of the present study support that muscles from the IB pig genotype have special characteristics, which may enhance the overall quality of meat compared with conventional or high-lean porcine breeds, even under identical management system, due to its particular fat composition and colour attributes.