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The purpose of the current study was to further characterize the performance and nitrogen retention differences previously observed between immunocastrated (IC) and surgically castrated (SC) pure Iberian pigs. Fifty-four pigs were used (three sexes: IC males, IC females and SC males), fed three isoenergetic diets (160, 140 and 120 g CP/kg DM; six pigs/treatment combination) from 40 kg BW until slaughter (105 kg BW). Plasmatic post-absorptive metabolites and hormones, and backfat tissue composition were determined. The IC males showed a trend towards higher plasmatic creatinine (p = 0.06) and IGF-1 concentrations than SC males and IC females (p < 0.001). SC males showed a higher predisposition to carcass fatness and insulin resistance compared to IC males. Plasmatic isoleucine concentration was higher in IC and SC males compared to IC females (p < 0.01), and valine was greater in IC males compared to the rest of the pigs (p < 0.001). Total branched-chain amino acids (AA) were greater in IC males than in IC females (p < 0.01). Total plasmatic essential AA concentrations tended to be greater in IC males (p = 0.09). The present results support the increased performance and nitrogen retention capacity previously observed in IC male Iberian pigs compared to SC males and IC females, which can be attributed to increased anabolic capacity related with lean growth in Iberian IC males.

The study analyzed the effect of supplemental zinc and betaine on meat quality and redox status of muscles (longissimus lumborum and gluteus medius) from heat- stressed pigs. Twenty-four pure Iberian pigs were assigned to one of three treatments (n = 8): control diet, Zn supplemented diet (120 mg/kg) and betaine supplemented diet (5 g/kg) that were all exposed to 30 °C during 28 days. No significant differences were observed in chemical composition and fatty acid profile of the muscles. The Zn diet improved the water retention capacity of longissimus, increased the antioxidant properties (ABTS and FRAP) and the glutathione peroxidase activity, and reduced the level of MDA. No significant effects associated to the betaine diet were observed in quality traits and antioxidant markers of muscles. These findings suggest that Zn supplementation may be used as a nutritional strategy to improve the antioxidant properties of meat of Iberian pigs subjected to heat stress conditions.

Heat stress is associated with impaired meat quality and disruption of redox balance. This study investigated the effect of chronic exposure to high temperature on meat quality and antioxidant markers of muscles (longissimus lumborum and gluteus medius) of growing Iberian pigs. Twenty-four pure Iberian pigs were allocated during 28 days to one of three treatments (n = 8/treatment): thermoneutral conditions (20C) and ad libitum feeding (TN), heat stress conditions (30C) and ad libitum feeding (HS) and thermoneutral and pair-fed with HS (TN-pf). Muscles of the HS group had greater intramuscular fat content than the TN-pf group and higher Zn levels than TN and TN-pf, whereas differences on fatty acid composition were negligible. Heat exposure did not affect pH, color coordinates of redness (a*) and yellowness (b*) and MDA values but had a positive influence on lightness and drip losses. Moreover, chronic heat stress stimulated the activity of antioxidant defenses SOD, CAT and GPx. The statistical factor analysis adequately classified the muscles studied, but was unable to differentiate samples according with treatments. Findings of the present study support an adaptive response of the Iberian pig to high temperatures and show the high Iberian meat quality even under adverse climate situations.

Immunocastration (IC, vaccination against gonadotropin releasing hormone (GnRH)) is one alternative to surgical castration (SC) for preventing sexual development and boar taint in male pigs. A temporal increase in performance has been described for IC pigs before the second vaccination against GnRH. The objective of this work was to assess the effects of IC on Iberian male and female pigs (fed diets of increasing CP content) on performance, nitrogen retention (NR) and digestibility, and carcass traits. Fifty-four pure Iberian pigs individually housed were allocated to a 3 × 3 factorial arrangement with three sex groups (IC males, IC females and SC males), three diets (153, 137 and 119 g CP/kg DM; 14 MJ metabolisable energy/kg DM) and six pigs per treatment combination. Pigs were vaccinated at 18 weeks of age (40 kg BW) and seven weeks later (70–80 kg BW) and fed at 0.9 × ad libitum on BW basis. Two digestibility and nitrogen balance assays were performed before and after the second vaccination, respectively. Pigs were slaughtered at 105 kg BW. Before the second vaccination, Iberian IC males showed higher growth rate (g/day), feed efficiency, NR (g/day) and efficiency of NR than the other groups (P < 0.001). The NR and efficiency of NR was 40% greater in IC v. SC males (P < 0.001). After the second vaccination, no differences in performance between sex groups were detected (P > 0.05). Growth rate and feed efficiency were higher in IC males than in the other groups for the whole experimental period (from the first vaccination to slaughter; P < 0.001). After the second vaccination, differences among sex groups in NR and the efficiency of NR disappeared (P > 0.05). NR efficiency was 0.177 on average. No significant effects of dietary CP were detected on performance. The NR was greater in pigs fed the 153 CP diet (17 to 37%; P > 0.05). Lean components of carcass (sirloin, loin and butt lean) were greater in IC males than in the other groups (0.001 < P < 0.05). There were

Betaine and conjugated linoleic acid (CLA) may improve pig performance and increase lean mass, but the mechanisms are not well understood. Gastrointestinal tract, pancreas, spleen and mesenteric fat comprise portal-drained viscera (PDV). Nutrient and energy availability of productive tissues may be compromised by PDV because of its anatomical situation and elevated oxygen consumption. The objective of this study was to determine if the use of betaine, CLA, or both in the diet affects the net portal appearance (NPA) of proteinogenic amino acids (AA; essential and non-essential AA) in Iberian pigs. Sixteen Iberian growing barrows (19 kg body weight (BW)) were randomly assigned to one of four experimental treatments (4 pigs/treatment): basal diet (control; barley and soybean meal-based (145 g crude protein (CP)/kg dry matter (DM) and 14.7 MJ metabolizable energy (ME)/kg DM)) supplemented or not with 5 g/kg betaine, 10 g/kg CLA, or 5 g/kg betaine +10 g/kg CLA. Three catheters were placed in each pig: in carotid artery and portal vein for blood sampling, and in ileal vein for para-aminohippuric acid (PAH) infusion to measure portal plasma flow (PPF). Blood samples were taken into heparinized tubes simultaneously from carotid artery and portal vein at 0, 0.5, 1, 1.5, 2, 3 and 6 h after feeding 1200 g of diet. Blood was centrifuged, haematocrit determined, and plasma stored until PAH and AA analyses. The PPF tended to be greater (15.0%, P=0.095) for control diet compared with the other three diets. Supplementation with betaine increased NPA of essential (59%, P<0.001), and non-essential (79%, P<0.001) AA of growing Iberian pigs and, therefore, the AA availability for peripheral tissues; however, supplementation with CLA decreased (122%, P<0.001), the NPA of most essential AA.

Wild-growing mushrooms could be a potential source of mineral elements The aim of this study was to analyze the mineral composition of 18 species of wild-growing mushrooms collected in a natural park from the Spanish southeast (province of Granada). Ca, Mg, K, Na, Fe, Cu and Zn, were determined by flame atomic absorption spectroscopy and P was analyzed colorimetrically by the vanadomolybdate procedure; the accuracy of methods was assessed by the use of certified reference materials. The contribution of mushrooms consumption to the mineral daily recommended intakes was calculated. Although large variations were observed between species, the most abundant mineral elements in the analyzed mushrooms were K and P, with average contents of 29.3 ± 8.1 and 8.60 ± 4.8 g/kg dry matter (dm), respectively. Low Na concentrations were observed (26.5–579 mg/kg dm), with the only exception of Amanita ovoidea, and high Fe values, exceeding in some cases 1000 mg/kg dm (such as in Lactarius deliciosus and Morchella conica). Mushrooms may be significant contributors of K and P in the human diet and also good sources of trace elements, especially Cu and Fe, providing negligible quantities of Na. Strong correlations were observed for Ca/Mg and Cu/Zn contents in the mushrooms analyzed.

The main characteristics of the Iberian breed, an autochthonous pig breed of the Iberian Peninsula, are presented in this chapter along with the results of a literatura review on productive traits. Reproductive performance was estimated by sow age at first parturition, litters per sow and year, piglets alive per litter, piglet weight at birth and at weaning, percentage of stillborn per litter, mortality at weaning, lactation length and farrowing interval. For growth performance, average daily gain and daily feed intake during lactation and in different growing phases are provided. Carcass traits were evaluated by age and weight at slaughter, hot carcass weight, carcass yield, backfat thickness measurements, muscle thickness and loin eye area. Meat quality traits of longissimus muscle (pH, objective colour measurements and intramuscular fat) were also assessed. The main part of the studies considered simulated practical production conditions in Iberian pig rearing although others evaluated a defined growing period, sometimes quite far from the usual comercial slaughter weight of this breed. Therefore, some figures should be interpreted with caution. Although a considerable number of studies on Iberian pig were included in the current review, scientific papers on reproductive performance and some meat quality parameters are still rather scarce.

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates—like fatty and lean pigs—may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty-eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine-adequate (AL) diet and lysine-deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p <.01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p <.001–p <.05), and lower of methionine (p <.001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p <.001–p <.05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or n

The aim of the present study was to determine the portal-drained viscera (PDV) heat production (HP) and net PDV flux of volatile fatty acids (VFA: Acetic, propionic and butyric acids) in Iberian pigs (34-kg bodyweight) fed with acorn from evergreen oak, and to ascertain whether there is an effect of acorn feeding over time. In addition, potential contribution of both parameters to the energy budget of the animal was calculated. The following two sampling periods were conducted with six gilts: After 1 day (I) and after 1 week (II) of acorn feeding. Postprandial PDV HP was 29% greater (P < 0.01) in Sampling period II than in Sampling period I, but net PDV flux of VFA was only slightly greater (5%, P > 0.1). Potential proportional contribution of VFA to the whole HP was almost identical in both sampling periods (0.057, on average), representing 0.109 (on average) of the metabolisable energy requirements for maintenance. Pigs adapted for 1 week to an acorn diet had increased PDV HP without an increase in the net PDV flux of VFA, indicating that, apparently, nutrients other than VFA were responsible for the increased PDV HP.

The Mediterranean diet is associated with a low incidence of physiologic and metabolic non-communicable diseases such as hypertension, obesity, and insulin resistance. These chronic diseases are closely related to oxidative status, which is determined by the balance between oxidant and antioxidant levels. The Mediterranean diet is rich in foods with important antioxidant properties, such as fruits and extra virgin olive oil. The aim of this work was to establish the relationship between dietary patterns, the total intake of polyphenols, and the levels of 8-isoprostanes in urine, as a marker of lipid peroxidation, in a group of healthy Spanish women. The main sources of dietary polyphenols were fruits, vegetables, pulses, nuts, and extra virgin olive oil. There was a significant and positive correlation between the estimated intake of polyphenols, total polyphenols excreted in urine, adherence to the Mediterranean diet, and the intake of specific food groups. A positive correlation was established between the total polyphenols in urine and the intake of raw extra virgin olive oil. However, a negative correlation was established between the amount of 8-isoprostanes in urine, total intake of polyphenols, adherence to the Mediterranean diet, and the intake of fruits and nuts. These results indicate an association between oxidative status and the intake of foods that are typical of the Mediterranean diet, in healthy women. Furthermore, the results demonstrate the use of urine 8-isoprostanes as a marker of adherence to the Mediterranean diet.

The health benefits of extra virgin olive oil (EVOO) are related to its chemical composition and the presence of bioactive compounds with antioxidant properties. The aim of this study was to evaluate antioxidant compounds (pigments, coenzyme Q10 (CoQ10) and phenolic compounds) and antioxidant properties of EVOO from the same region comparing different cultivars (Hojiblanca and Arbequina), harvest year and crop stage. Antioxidant properties of oils were studied before and after a gastrointestinal digestion process, by in vitro assays (DPPH, ABTS and FRAP) and antioxidant markers in Caco-2 cells (reactive oxygen species production). The content of bioactive compounds measured was significantly affected by cultivar and harvest year (except for carotenoids) and by the crop stage (except for coenzyme Q10). Higher amounts of coenzyme Q10 were observed in Hojiblanca than in Arbequina EVOO. Total phenol content and antioxidant properties were also different depending on cultivar and harvest year and the in vitro digestion process strongly improved antioxidant marker values. Antioxidant potential in bioaccessible fractions was mainly related to the content of coenzyme Q10 and phenolic compounds in EVOO. Chemometric analysis showed that the oils were clearly classified by cultivars, harvest and crop stage, according to the chemical composition and antioxidant activity analyzed in the present study

This study analyzes quality traits of longissimus lumborum and gluteus medius in surgically castrated (SC) males, inmunocastrated (IC) males and IC female Iberian pigs reared in intensive conditions (n = 18/sex). Vaccination with Improvac® was applied at 18 and 26 weeks of age and slaughtering at 31 weeks. At such conditions, notable sex differences were found. Both muscles of IC males were less red (P <.01), longissimus had lower intramuscular fat (P <.01) and gluteus less Fe content (P <.01) than SC males and IC females. Loins from IC males also exhibited higher drip losses (2.7% at 24 h) than SC males (1.9%) and IC females (1.6%) (P <.001). Fatty acid composition of muscles differed among sexes, especially polyunsaturated fatty acids, which varied as follows: IC males > IC females > SC males in both muscles. It was concluded that meat quality traits differed between inmunocastrated and surgically castrated male Iberian pigs.

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.

Immunocastration has proved to be an effective strategy to prevent sexual development and boar taint in pigs. Previous results indicate that immunocastrated (IC) pigs exhibit better performance than surgically castrated (SC) pigs. In addition to animal welfare benefits, this fact could be of interest for Iberian pigs, as their growth capacity rapidly diminishes as animal ages. The purpose of this study was to examine the effects of immunocastration on Iberian pig performance, protein utilization, and carcass traits under different dietary protein concentrations. Pure Iberian pigs (n=27) were used as follows: 3 sexes (IC males, IC females, SC males); 3 isoenergetic diets (160, 140 and 120 g CP/kg DM); 3 pigs/group. Pigs were vaccinated against Gonadotropin Releasing Hormone at 4.3 months (40 kg) and 6 months (70-80 kg) of age. Experimental diets were offered to individually-housed pigs from 40 to 100 kg BW. Digestibility and N-balance assays were performed at 50 and 90 kg BW, respectively. Pigs were slaughtered at 100 kg BW. Preliminary results indicate greater growth rate for IC males (803 vs 706 and 696 g/d, for IC males, SC males and IC females, respectively; P < 0.001). Feed efficiency (G:F) was greater for IC males (0.289 vs 0.260 and 0.263; P < 0.01). Moreover, IC males exhibited increased carcass length and greater relative weights for most lean cuts, but they also had smaller carcass yield and belly proportions than the rest of groups. No relevant differences related to dietary treatments were detected. Further research would help to elucidate possible effects of immunocastration on Iberian pig lean growth.

Along this review we describe the results from a series of experiments performed to assess the utilization of dietary protein by the Iberian pig throughout different stages of its productive cycle. Nutritional dose-response studies involving several isoenergetic treatments differing in protein concentration -all with similar amino acid profile following the ideal protein concept- along with comparative growth and metabolic studies with conventional breeds have been performed. Our observations reveal that the capacity of this breed for protein accretion is rather limited compared to that of conventional breeds at similar stages of growth, and suggest the need for reducing the concentration of protein in the diet of the Iberian pig to comply with its metabolic profile. Basic comparative studies have brought to light information to help us explaining some of the metabolic peculiarities of this autochthonous breed of pigs, like the low capacity to accrete protein and lean tissue. We summarise all the information gathered in several experiments and provide recommendations on the concentration and composition of dietary protein in the diet for purebred animals during different phases of growth. Adequate nutritional management, particularly dietary protein provision, improves the efficiency of utilization of dietary protein and results in relevant economic, environmental and animal welfare benefits.

Trace elements (i.e. Fe, Cu and Zn) are essential for maintaining importantphysiological processes, and dietary requirements in pigs should be carefully established. Asa valid approximation to study trace mineral needs, an experiment was conducted to analysethe content of Fe, Cu and Zn in muscles from two porcine genotypes. Sixteen pigs (8 Iberian, IB, and 8 Landrace × Large White, LDW) were used. They were fed isoenergetic diets (14 MJ/Kg DM) containing either 130 or 170 g CP/kg DM, to match protein requirements of each breed (4 pigs/genotype and CP level).The pigs were sacrificed at 115 kg LW, and samples of longissimus dorsiandbiceps femorismuscles were obtained.Fe and Zn concentration in muscles was significantly influenced by genotype, being higher amongIB pigs. Asignificant effect of dietary protein was observed in the IB group, as pigs fed with higher protein levels had lower values of Fe in both muscles. Cu content was not affected by genotype or diet. These results indicate that deposition of trace minerals, such as Fe and Zn, is under genetic control, and support the importance of meat from IB pigs as a good source of Fe and Zn

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 stun- ning. 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, P < 0.05). Intramuscular fat content increased in longissimus dorsi of Iberian (P < 0.05) and in biceps femoris of both pig genotypes (P < 0.01) when fed Lys-deficient diets. Oleic acid increased (P < 0.05) and PUFA acid decreased (P < 0.01) in longissiumus dorsi and biceps femoris of pigs of both genotypes fed Lys-deficient diets. The proportion of oxidative fibers (P < 0.001) and free l-carnitine content (P < 0.05) increased in longissimus dorsi of both pigs types fed Lys-deficient diets. Plasma creatinine was greater in LDW

Thirty entire male Iberian (IB) pigs of 12 kg initial BW were used to study the effects of dietary protein-to-energy ratio on performance, body protein accretion, and tissue composition. Two nutritional regimes were supplied at 3 stages of growth (Phase I, from 12 to 30 kg BW; Phase II, from 30 to 45 kg BW; and Phase III, from 45 to 100 kg BW): the first regime (RefP/E) was formulated to provide optimum protein-to-energy ratios for castrated IB pigs at several stages of growth from 10 to 100 kg BW; the second (IncP/E), for which an overall increase of 2.5 g digestible protein/MJ ME was provided, would allow an increased potential for lean tissue growth presumably well above that expected for the entire male of an obese pig breed. The pigs were surgically castrated at 45 kg BW and slaughtered at about 100 kg BW. In Phases I and II, in which feed was provided ad libitum, no significant differences between dietary treatments in ADG (580 ± 10 and 740 ± 11 g, on average, respectively), G:F (0.475 ± 0.004 and 0.362 ± 0.005, on average, respectively), and gain:ME intake ratio (37.8 ± 0.4 and 26.1 ± 0.4 g/MJ, on average, respectively) were found (P > 0.05). After surgical castration, for the entire fattening period (Phase III), ADFI was fixed and highly restricted. A lower gain:ME intake ratio (14.0 vs. 15.1 g/MJ; P < 0.01) was obtained when the diet with the highest digestible protein:ME ratio was offered (IncP/E). With this regime, body protein accretion significantly improved in the IB boar growing from 12 to 45 kg BW, irrespective of the stage of growth, although the amount of protein accreted was notably enhanced at the later stage (75 vs. 85 g/d in Phase I [P < 0.05] and 110.5 vs. 151 g/d in Phase II [P < 0.001]). However, the efficiency of utilization of dietary N remained unchanged irrespective of the diet fed (P > 0.05). In contrast, in the fattening stage, similar daily rates of N retention (P > 0.05) were found, in spite of the observed differences in digestible

The objective of the present work wasto investigate the effect of dietary Lys deficiency upon intramuscular fat (IMF) concentrationand its fatty acid profile in an obese (Iberian, IB) and aconventional pig genotype (LDW). We used 28 castrated male pigsof 10 kg of initial BW, 14 from each type. Pigs were fed two diets, based on barley, maize, gluten meal and soybean meal, with identical composition,except for their Lys content (0.98% Lys, diet AL, adequate in Lys; and0.47% Lys, diet DL, deficient in Lys). The rest of nutrients met or exceeded recommendations. Seven pigs from each type were fed one of the dietsat 85% of ad libitumof the Iberian pigs. At 25 kg BW pigs were slaughtered and L. dorsiand B. femorismusclessampled.Performance was reduced in both pig types fed LD diets, particularly LDW pigs (P<0.05).Pigs fed LD diets showed higher IMF contentand oleic acid proportion,and lowerrelative percentage of poliinsaturated fatty acids. Feeding Lys deficient diets canbe a suitable strategy for increasing meat quality,both in obese and lean pig types,although further research is needed to deep our knowledge on the mechanism involved in thesechanges

© 2014 Ministerio de Agricultura Pesca y Alimentacion. All Rights Reserved. A meta-analysis was made of data from a total of 211 growing-finishing Iberian (IB) pigs from four separate and independent sets of trials. Within each set of trials, a factorial arrangement of treatments was used, involving several concentrations of ideal protein in the diets and two or three levels of feed intake. Pigs were slaughtered at several stages of growth from 10 to 150 kg body weight (BW). The partition of dietary protein in the body of the pigs, the empty-body gain (EBG), the chemical composition of EBG, growth of primal cuts in the cold eviscerated carcass (without head, feet, and tail), and mass of dissected tissues in trimmed shoulder and ham were determined. Linear regression equations allowed estimating N requirements for maintenance as 175 mg/(kg BW0.75 · kg dry-matter intake) · d–1 and an average value for the net efficiency of utilization of the dietary protein apparently absorbed of 0.386. In pigs offered adequate protein to energy diets, EBG was predicted as a function of average BW and feeding level (p < 0.001). Multiple regression equations were constructed, which derived nutrient (g kg–1) or energy (MJ kg–1) composition of EBG as a function of empty-body weight (EBW), dietary protein to energy ratio, and level of feeding (p < 0.001). These predictive equations, not applicable to pigs of lean and conventional genotypes, can contribute to the design of optimal feeding strategies to improve the efficiency of IB pig production systems and to achieve high quality standards in end products for the market.

To determine whether the energy balance of goats or characteristics of the diet consumed were the principal factors that determined milk production, feeding and digestion trials were carried out using two groups of 5 Granadina goats. The concentrate fraction of both diets was the same, but the forage fraction of the diets differed. In diet 1, the forage was in the form of long alfalfa hay, and, in diet 2, forage was in the form of pelleted alfalfa. Intake and the forage to concentrate ratio of the two diets were not significantly different, although diet 2 was more digestible. The amount of fat and protein in the milk depended on energy intake and not on dietary treatment. The milk protein of goats fed diet 2 was higher in casein. No sensible differences were noted in the fatty acid composition of the milk. Nitrogen and metabolizable energy utilization for milk production was greater for goats fed diet 2. According to the results obtained, it would seem advantageous to use pelleted alfalfa rather than alfalfa hay in the diets of goats.

[EN] Energy metaboclism of the Granadina kid goat and the Segureña lamb was analysed by an experiment on different feeding levels and comparative slaughter. The metabolizable energy (ME) intake, total energy retention, energy retained as protein and energy retained as fat were determined in both kinds of animal for their first 2 months of life. ME requirements for maintenance, ME efficiencies for energy retention and ME intake values at which protein retention and fat deposition begin to occur were estimated by the regression method. The estimated ME requirements for maintenance and ME efficiencies for energy retention were: 456 kJ per kg0.75 per day and 0.55 for kid goats, and 393 kJ per kg0.75 per day and 0.54 for lambs, respectively. Values of ME intake at which protein retention and fat deposition begin to occur were: 258 and 575 kJ per kg0.75 per day for kid goats, and 428 and 362 kJ per kg0.75 per day for lambs, respectively. According to the results obtained, it was deduced that kid goats compared with lambs show a higher ME requirement for maintenance together with a higher partial efficiency of ME utilization for protein retention and a lower partial efficiency of ME utilization for fat deposition., [ES] Por medio de un ensayo de alimentatioń bajo diferentes niveles de ingesta y método de los sacrificios comparados, se analizó el metabolismo energético del cabrito y cordero prerrumiante. Para estas dos clases de animales y para sus dos primeros meses de vida, se determinaron las tasas de ingesta de energía metabolizable, energía total retenida y energía retenida como proteína y grasa. A partir de estos valores y por el método de regresión, se estimaron las necesidades de energía metabolizable para mantenimiento, las eficiencias de Utilización de la energía metabolizable para la retención así como las ingestas energéticas a partir de las cuales comienza en estos animales, la retención de proteína y depósito de grasa. Los valores de necesidades de mantenimiento y eficiencias de utilización de la energía metabolizable para la retención, fueron: 465 kJ/kg0.75/día y 0.55 para el cabrito y, 393 kJ/kg0.75/día y 0.54 para el cordero, respectivamente. Los valores de ingesta energética a partir de los cuales comenzaba la retención de proteína y el depósito de grasa, se estimaron iguales a, 258 y 575 kJ/kg0.75/día para el cabrito y, 428 y 362 kJ/kg0.75día para el cordero, respectivamente. De acuerdo con los resultados obtenidos se deduce que el cabrito en comparacíon con el cordero, presenta unas necesidades energéticas para mantenimiento mayores, mostrando al mismo tiempo una mayor y menor eficiencia partial de utilización de una ingesta energética para la retencion de proteína y depósito de grasa, respectivamente.

Thirty-two kid goats of the Granadina breed were used in four trials of three factors: milk type (goat milk and milk replacer), intake level (1·86 and 2·48 maintenance) and slaughter age (15, 30, 45 and 60 days). Weaning was carried out between the 31st and 45th days. The composition of the carcass and its different cuts and the development of the stomach compartments were studied. Both the high intake level and use of goat milk produced a statistically greater fat proportion in the carcass. At 30 days of age in kids given goat milk at the high intake level the fat proportion of the carcass was 130 g/kg. The variations in bone proportions were inverse to those for fat. The muscle proportions were affected by age, overall. The tissue composition of the different cuts showed similar responses to those in the carcass. The stomach compartments were affected most by age. The results show that kids of the Granadina breed have a good fattening capacity. The feeding and weaning system used here produced kids by 60 days of age with stomach compartments similar in proportion to those of adult goats.