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Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs
- R. Barea, B. Isabel, R. Nieto, C. López-Bote, J. F. Aguilera
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The lipid content and fatty acid (FA) profile in pig tissues are strongly influenced by genotype and nutrient supply, with implications in meat quality. The de novo lipid synthesis and pattern of FA unsaturation could be an important cause of variation in the overall efficiency of energy utilization among breeds. To test the effects of pig genotype and CP supply on the evolution of back-fat tissue FA profile throughout the growing and finishing stages, 32 Iberian (IB) and Landrace × Large White (LR × LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 × ad libitum intake of IB pigs) was used. Subcutaneous fat samples were taken at the dorso-lumbar region at ∼38, 50, 65, 90 and 115 kg BW. Higher proportions of total monounsaturated FA (MUFA; P < 0.01) and lower proportions of total saturated FA (SFA; P < 0.01 to 0.05) were found in the outer back-fat layer of pigs both at 50 and 115 kg BW. Pig genotype affected the FA composition of both subcutaneous back-fat layers. The proportions of C18:0 and SFA in fat tissue were higher in IB than in LR × LW pigs from 38 to 65 kg BW, especially in the outer layer. In addition, MUFA contents were higher in IB pigs at 115 kg BW in both layers (+5% on average; P < 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR × LW pigs, irrespective of the stage of growth and back-fat layer (P⩽0.02). At 50 kg BW, pigs receiving the high-protein diet presented the highest C18:2 n-6, C18:3 n-3, C20:5 n-3 and PUFA contents. A significant genotype × CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR × LW pigs when offered the 17% CP diet (P < 0.05). Higher C16:0 and SFA contents (+5%; P = 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype × CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P = 0.03). Our results suggest that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA profile of IB and LR × LW pigs under identical nutritional management. They could be also relevant to explain the low efficiency of nutrient and energy utilization in the IB pig.
Response of piglets to the valine content in diet in combination with the supply of other branched-chain amino acids
- M. Gloaguen, N. Le Floc'h, L. Brossard, R. Barea, Y. Primot, E. Corrent, J. van Milgen
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The branched-chain amino acids (BCAA) valine (Val) and isoleucine (Ile) are considered to be among the next-limiting amino acids for growth in piglets. In earlier studies, we estimated the standardized ileal digestible (SID) Val : Lys (lysine) requirement to be at least 70%, whereas the Ile : Lys requirement may be as low as 50%. Because the BCAA partially share a common route of catabolism, the supply of one BCAA may affect the availability of the other BCAA. Four experiments were conducted to determine the response of 6-week-old piglets to the Val supply in relation to the other BCAA. A deficient supply of Val or Ile typically results in a reduction in average daily feed intake (ADFI). Experiment 1 was designed to determine the effect of a limiting Val supply, independent of the effect on feed intake. In a dose–response study using restrictively fed piglets, nitrogen retention did not increase for an SID Val : Lys supply greater than 64%. In the remaining experiments, piglets were offered feed ad libitum using ADFI, average daily gain (ADG) and gain-to-feed ratio as response criteria. The interaction between the Val and leucine (Leu) was studied in Experiment 2 in a 2 × 2 factorial design (60% and 70% SID Val : Lys, and 111% and 165% SID Leu : Lys). Performance was considerably lower in piglets receiving 60% Val : Lys compared with those receiving 70% Val : Lys and was lowest in piglets receiving the diet with low Val and high Leu content. To further evaluate the interaction between Val and Leu, a dose–response study was carried out in which the response to Val supply was studied in combination with high Leu supply (165% Leu : Lys). Using a curvilinear-plateau model, the average SID Val : Lys requirement was 72%. However, low Val supply (60% SID Val : Lys) reduced performance by 13% to 38%, which was much greater than what we observed in earlier studies. Experiment 4 was carried out to test the hypothesis that the Val requirement is not affected by low Ile supply (50% SID Ile : Lys). Performance was not improved for Val : Lys supplies greater than 65%, which may indicate that Ile (and not Lys) was second-limiting in this study. In conclusion, the first response of piglets to deficient Val supply appears to be a reduction in ADFI, rather than a reduction in ADG or nitrogen retention. A large supply of Leu may not affect the Val requirement per se, but may aggravate the consequences of Val deficiency.
Effects of pig genotype (Iberian v. Landrace × Large White) on nutrient digestibility, relative organ weight and small intestine structure at two stages of growth
- R. Barea, R. Nieto, F. Vitari, C. Domeneghini, J. F. Aguilera
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Although the effects of pig genotype on total-tract apparent digestibility (TTAD) have been widely reported in the literature, there is controversial information on the digestive capacity of indigenous breeds compared with lean-type pigs. The strategy of this study was to test the effects of pig genotype and crude protein (CP) supply on performance, digestive utilization of nutrients, relative organ weight and morphometric analysis of the small intestine. Thirty-eight Iberian (IB) and Landrace × Large White (LD) pigs were used. Three pigs per genotype were slaughtered at approximately 15 kg BW. The remaining pigs were fed one of two diets differing in CP content (13% or 17% as fed) using a pair-fed procedure. Feeding level was restricted at 0.8 × ad libitum of IB pigs. Nutrient digestibility and nitrogen (N) balance trials were performed at 30 and 80 kg BW. Four pigs per dietary treatment and genotype were slaughtered at approximately 50 and 115 kg BW. The gastrointestinal tract and the rest of the visceral organs were weighed and samples of the small intestine were taken to carry out histological and histometrical studies. Daily gain and gain-to-feed ratio were higher in LD than in IB pigs during the fattening and growing–fattening periods (P < 0.01). N TTAD was significantly higher for LD pigs at 30 kg BW (P < 0.05), whereas at 80 kg BW we observed greater values for digestibility of organic matter and energy in IB pigs (averaging 1.5%, P < 0.01). Both N retention (NR) and efficiency of NR were increased in LD pigs at 30 and 80 kg BW (30% as mean value). The proportional weight of the small intestine was greater in LD than in IB pigs at 50 and 115 kg BW. Histometry showed that IB presented a lower muscle layer thickness than LD pigs in ileum, irrespective of the BW (P < 0.05). In contrast, LD pigs showed approximately 10% higher ileal villi length and villi-to-crypt ratio than IB pigs at 115 kg BW. CP supply affected to a larger extent the small intestinal micro-anatomical structure of LD pigs at 50 kg BW. In conclusion, our results suggests that although the higher growth rate, NR and efficiency of NR observed in LD pigs might be associated with presumably more efficient structural aspects of the small intestine, the main differences between the two genotypes should be attributed to a larger extent to protein and energy utilization in tissues with consequences for the overall efficiency of energy use.
A sulfur amino acid deficiency changes the amino acid composition of body protein in piglets
- J. A. Conde-Aguilera, R. Barea, N. Le Floc’h, L. Lefaucheur, J. van Milgen
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Experiments carried out to determine the amino acid requirement in growing animals are often based on the premise that the amino acid composition of body protein is constant. However, there are indications that this assumption may not be correct. The objective of this study was to test the effect of feeding piglets a diet deficient or not in total sulfur amino acids (TSAA; Met + Cys) on nitrogen retention and amino acid composition of proteins in different body compartments. Six blocks of three pigs each were used in a combined comparative slaughter and nitrogen balance study. One piglet in each block was slaughtered at 42 days of age, whereas the other piglets received a diet deficient or not in TSAA for 19 days and were slaughtered thereafter. Two diets were formulated to provide either 0.20% Met and 0.45% TSAA (on a standardized ileal digestible basis) or 0.46% Met and 0.70% TSAA. Diets were offered approximately 25% below ad libitum intake. At slaughter, the whole animal was divided into carcass, blood, intestines, liver, and the combined head, tail, feet and other organs (HFTO), which were analyzed for nitrogen and amino acid contents. Samples of the longissimus muscle (LM) were analyzed for myosin heavy chain (MyHC) and actin contents. Nitrogen retention was 20% lower in piglets receiving the TSAA-deficient diet (P < 0.01). In these piglets, the nitrogen content in tissue gain was lower in the empty body, carcass, LM and blood (P < 0.05) or tended to be lower in HFTO (P < 0.10), but was not different in the intestines and liver. The Met content in retained protein was lower in the empty body, LM and blood (P < 0.05), and tended to be lower in the carcass (P < 0.10). The Cys content was lower in LM, but higher in blood of piglets receiving the TSAA-deficient diet (P < 0.05). Skeletal muscle appeared to be affected most by the TSAA deficiency. In LM, the Met content in retained protein was reduced by 12% and total Met retention by more than 60%. The MyHC and actin contents in LM were not affected by the TSAA content of the diet. These results show that a deficient TSAA supply affects the amino acid composition of different body proteins. This questions the use of a constant ideal amino acid profile to express dietary amino acid requirements, but also illustrates the plasticity of the animal to cope with nutritional challenges.
Effects of the dietary protein content and the feeding level on protein and energy metabolism in Iberian pigs growing from 50 to 100 kg body weight
- R. Barea, R. Nieto, J. F. Aguilera
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Nutritional requirements of the Iberian pig, a slow-growing, obese porcine breed, are not well defined and seem to differ from those of conventional or high-performing pigs. The effects of the dietary protein content and the feeding level on the utilisation of metabolisable energy (ME) and the rates of gain, protein, and fat deposition were studied with 81 Iberian castrates growing from 50 to 100 kg body weight (BW) by using the comparative slaughter technique. The animals were fed 4 diets providing 145, 120, 95, and 70 g ideal crude protein (CP) per kg dry matter (DM), and containing 13.94, 14.29, 14.56, and 14.83 MJ ME per kg DM, respectively. Three levels of feeding were evaluated: 0.60, 0.80, and 0.95 × ad libitum intake. Growth rate increased (linear and quadratic, P < 0.001) as the dietary ideal CP content decreased. It also increased with the feeding level (linear, P < 0.001; quadratic, P < 0.05). Gain:feed and gain:ME intake improved by decreasing the ideal CP content in the diet (linear, P < 0.001 and P < 0.05, respectively; quadratic P < 0.001 for both variables). Increasing the feeding level improved linearly gain:feed and gain:ME intake ( P < 0.001). Protein deposition (PD):ME intake ranged between 1.23 and 1.44 g/MJ, and it showed a tendency to reach the maximum value when the diet providing 95 g ideal CP per kg DM was fed (quadratic, P = 0.078). When this diet was offered at 0.95 × ad libitum, PD reached a maximum value of 71 g/day. This dietary treatment resulted in average values for average daily gain and retained energy (RE) of 854 g/day and 21.4 MJ/day, respectively. The average rate of gain was 19.93 g/MJ increase in ME intake, equivalent to an energy cost of 50.2 kJ ME per g gain, irrespective of the dietary ideal CP content. Also, the overall marginal efficiency of protein deposition (ΔPD:ΔME; g/MJ) was 1.34. Increasing the feeding level led to increases in PD (linear, P < 0.001) and RE (linear, P < 0.001; quadratic, P < 0.01) irrespective of the dietary ideal CP concentrations. Between 50 and 100 kg BW, the chemical composition of 1 kg gain averaged 78, 592, 28.7, and 284 g for CP, fat, ash, and water respectively. The net efficiency of use of ME for growth ( kg) and the maintenance energy requirements were 0.606 and 396 kJ/kg BW 0.75 per day, respectively. The results support earlier findings that the genotype has marked effects on protein and energy metabolism of growing pigs and underline important compositional differences of the Iberian pig compared with conventional or modern porcine genotypes.
Effects of dietary protein content and feeding level on carcass characteristics and organ weights of Iberian pigs growing between 50 and 100 kg live weight
- R. Barea, R. Nieto, L. Lara, M.A. García, M.A. Vílchez, J.F. Aguilera
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- Animal Science / Volume 82 / Issue 3 / June 2006
- Published online by Cambridge University Press:
- 09 March 2007, pp. 405-413
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- June 2006
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The effects of dietary protein content and level of feeding on carcass characteristics and organ weights were studied in castrated male Iberian pigs growing from 50 to 100 kg live weight (LW). Animals were offered four diets providing 145, 120, 95 and 70 g ideal crude protein (CP) per kg dry matter (DM) and 13·94, 14·29, 14·56 and 14·83 MJ metabolizable energy (ME) per kg DM, respectively. Three levels of feeding were assayed: 0·60, 0·80 and 0·95 of ad libitum intake. The pigs were slaughtered at 100 kg LW. Daily gain in carcass (carcass gain, g/day) and protein deposition (PD, g/day) in this component attained 76·2% and 78·8% of whole-body average daily gain and PD, respectively. Carcass gain improved with each decrease in dietary CP from 145 up to 120 g/kg DM and then levelled off. A small but significant effect of dietary CP on carcass composition was observed, due to an enhanced fat deposition in pigs fed the lowest protein content diet. Mean values of protein, fat, ash and water contents in the carcass were 101·8, 522·7, 27·6 and 353·7 g/kg respectively. PD in the eviscerated carcass was not affected significantly by dietary protein level but tended to reach a maximum value with the diet that provided 95 g CP per kg DM: 55·7 g/day at the highest feeding level assayed. Carcass energy retention (MJ/day) increased significantly ( P<0·001) with decreasing dietary protein supply and on increasing level of feeding. Raising feed intake resulted in a significant decrease for carcass and a concomitant increase for viscera, as proportions of empty body weight ( P<0·05 and P<0·001, respectively). Proportional weights of shoulder and ham were not affected either by dietary CP content or feeding level. Proportionate weights of dissectable fat in the shoulder and intermuscular and subcutaneous fat in the ham were not affected by CP content of the diet. In contrast, intermuscular fat content of ham was increased by feeding level ( P<0·05), likely with implications for the quality of the cured meat product.
The use of isotopic dilution techniques to evaluate the interactive effects of Rhizobium genotype, mycorrhizal fungi, phosphate-solubilizing rhizobacteria and rock phosphate on nitrogen and phosphorus acquisition by Medicago sativa
- M. TORO, R. AZCÓN, J. M. BAREA
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- The New Phytologist / Volume 138 / Issue 2 / February 1998
- Published online by Cambridge University Press:
- 01 February 1998, pp. 265-273
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- February 1998
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A pot experiment was designed to evaluate the interactive effects of multiple microbial inoculation treatments and rock phosphate (RP) application on N and P acquisition by alfalfa plants using 15N and 32P isotopes. The microbial inocula consisted of a wild type (WT) Rhizobium meliloti strain, its genetically modified (GM) derivative, which had an enhanced competitiveness, the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, and a phosphate-solubilizing rhizobacterium (Enterobacter sp.). Inoculated micro-organisms became established in the root tissues and/or in the rhizosphere soil of alfalfa plants (Medicago sativa L.). The GM Rhizobium strain did not interfere with AM formation. Inoculated phosphate-solubilizing rhizobacteria established in the alfalfa rhizosphere, but the level of establishment was lower where the natural population of phosphate-solubilizing bacteria was stimulated by AM inoculation and RP application. The stimulation of these indigenous bacteria was also greater in the rhizosphere of alfalfa nodulated by the GM Rhizobium. Improvements in N and P accumulation in alfalfa corroborate beneficial effects of the improved GM Rhizobium on AM performance, in RP-amended plants. Inoculation with Enterobacter did not improve the AM effect on N or P accumulation in the RP-added soil, but it did in the non RP-amended controls. Measurements of the 15N[ratio ]14N ratio in plant shoots indicated enhanced N2 fixation rates in Rhizobium-inoculated AM-plants, over that achieved by the same Rhizobium strain in non-mycorrhizal plants. Regardless of the Rhizobium strain and of whether or not RP was added, AM-inoculated plants showed a lower specific activity (32P[ratio ]31P) than did their comparable non-mycorrhizal controls, suggesting that the plant was using otherwise unavailable P sources. The phosphate-solubilizing, AM-associated, microbiota could in fact release phosphate ions, either from the added RP or from the indigenous ‘less-available’ phosphate. Deficiency in Ca concentration in soil solution in the neutral test soil might benefit P solubilization. The proportion of plant P derived either from the labelled soil P (labile P pool) or from RP was similar for AM inoculated and non-mycorrhizal controls (without Enterobacter inoculation) for each Rhizobium strain, but the total P uptake, regardless of the P source, was far higher in AM-plants. Enterobacter inoculation seems to improve the use of RP in the rhizosphere of non-mycorrhizal plants inoculated with the WT Rhizobium.