Contrasting cellularity on fat deposition in the subcutaneous adipose tissue and longissimus lumborum muscle from lean and fat pigs under dietary protein reduction

The production of pork with high amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the pig industry and consumers. Herein, we question the impact of dietary protein reduction (18% v. 13%) on fat deposition in the subcutaneous adipose tissue (SAT) and longissimus lumborum (LL) muscle using genetically diverse pigs for body fatness (lean v. fat). A clear effect of genotype was observed on plasma insulin (P=0.004) and leptin (P<0.001), as well as on backfat thickness (P<0.001), with the fat pigs having higher values. Accordingly, IMF was higher in the fat pigs, when compared with their lean counterparts (P=0.003), which was supported by enlarged adipocytes (P<0.001). The area of lipid droplets within the LL fibres (P=0.039) and extramyocellular lipids number (P=0.017) were increased in pigs fed reduced protein diets, regardless of genotype, which is consistent with higher levels of plasma triacylglycerols (P=0.002). The gene-expression pattern of lipogenic factors in the SAT was distinct from the LL muscle. In the SAT, PPARG expression was similar among genotypes (P>0.05), whereas in the LL muscle it was higher in the lean pigs (P=0.023), especially when fed on low protein diet (P=0.057). The CEBPA and FABP4 mRNA levels were increased in the SAT of fat pigs (P<0.001), without changes in the LL muscle (P>0.05). The influence of diet on FABP4 expression in the SAT was dependent on pig’s genetic background (P=0.005). In conclusion, fat deposition was clearly influenced by genotype and, to a lesser extent, by dietary protein level, the SAT being more sensitive than the LL muscle. One can speculate that the pathways involved in lipid metabolism are downregulated in intramuscular adipocytes when compared with SAT fat cells. This result might be a direct consequence of the relatively low proportion of adipocytes found in the LL muscle.     

The rearing system modulates biochemical and histological differences in loin and ham muscles between Basque and Large White pigs

Conventional pork production, based on highly selected breeds for growth efficiency and carcass leanness, is generally considered to decrease pork quality. In contrast, non-selected breeds produced in extensive systems are associated with high pork quality, which is generally attributed to higher intramuscular fat (IMF) content and less glycolytic muscle metabolism. The present study aimed to determine biochemical, histological and quality traits of loin and ham muscles of pigs from selected Large White (LW) and local French, non-selected Basque (B) breeds. Pigs were reared in a conventional indoor (C, slatted floor), alternative (A, indoor bedding and outdoor area) or extensive system (E, free range, B pigs only). A total of 100 castrated males were produced in 2 replicates, each containing 5 groups of 10 pigs based on breed and system: LWC, LWA, BC, BA and BE. The glycolytic longissimus muscle (LM) and semimembranosus muscle (SM), and the deep red (RSTM) and superficial white (WSTM) portions of semitendinosus muscle (STM) were studied at 145 kg BW. Overall, breed induced stronger effects on muscle traits than the rearing system, among which the E system induced greater changes. The lower muscle growth of B pigs was associated with fewer muscle fibers and a smaller cross-sectional area (CSA) of glycolytic fibers (P < 0.01). The SM was less glycolytic and more oxidative in B than in LW pigs (P < 0.001). The WSTM followed a similar trend, with a larger relative area of type I fibers in B pigs. In contrast, the LM and RSTM were more oxidative in LW pigs. B pigs had higher IMF content and ultimate pH in all muscles, along with lower glycolytic potential, less light and redder meat in the LM and SM (P < 0.001). Compared to the C system, the A system induced only a shift towards a more oxidative metabolism in the LM and a smaller fiber CSA in the RSTM of LW pigs (P < 0.05), without influencing pork quality traits. Compared to BC pigs, BE pigs had a more oxidative and less glycolytic muscle metabolism, along with higher ultimate pH, lower lightness and redder meat (P < 0.01), but similar IMF content. Overall, results indicate that influences of breed and rearing system on muscle properties depend on muscle type, and that IMF content and fiber-type composition are unrelated traits that can be modified independently by genetic or rearing factors.     

Meishan neonatal piglets tend to have higher intestinal barrier function than crossbred neonatal piglets

Meishan pigs tend to have higher disease resistance than commercial breeds, although more studies are needed to confirm this difference. This study compared intestinal barrier function between Meishan and crossbred neonatal piglets to provide guidance for both the breeding and nutritional regulation of pigs. Six Meishan piglets and 6 Duroc × (Landrace × Yorkshire) crossbred neonatal piglets (all with normal birth weights) were obtained and allocated into the MEIS and CROSS groups, respectively. Intestinal morphology, goblet cell numbers, antioxidant enzyme activity, and cytokine gene and tight junction protein expression were assessed. The results showed that BW was lower in the MEIS group than in the CROSS group (P < 0.01). The relative lengths of the duodenum (P < 0.05), jejunum (P < 0.01) and ileum (P < 0.01) in the MEIS group were higher than those in the CROSS group. Compared with the CROSS group, the MEIS group exhibited shorter villus lengths in the duodenum and jejunum (P < 0.01), a shallower crypt depth in the ileum (P < 0.001) and denser and longer microvilli in the intestine. The numbers of GCs in the duodenum (P < 0.01) and jejunum (P < 0.001) and the activity levels of glutathione peroxidase (P < 0.05) in the jejunum and of catalase (P < 0.01) and superoxide dismutase (P < 0.01) in the ileum were higher in the MEIS group than in the CROSS group. Compared with the CROSS group, the MEIS group exhibited higher gene expression levels of interleukin (IL) 4 and interferon γ (IFNγ) in the jejunum (P < 0.05); IL2 (P < 0.05), IL4 (P < 0.01) and IFNγ (P < 0.001) in the ileum; and mucin 2 (P < 0.01) and occludin (P < 0.05) in the duodenum. In conclusion, Meishan neonatal piglets showed lower birth weights but higher intestinal barrier function than crossbred piglets.     

Meat and fat quality of Krškopolje pigs reared in conventional and organic production systems

Data on production traits of the only Slovenian autochthonous pig breed, the Krškopolje pig, is very scarce. Krškopolje pigs are reared in conventional and organic production systems, which were compared in the present study. After weaning, 24 barrows were assigned within litter to either conventional (CON) or organic (ECO) rearing system. Group CON (n=12) was housed indoors in two pens (7.5 m²) with partly slatted floor. Group ECO (n=12) was held in a sty with sheltered area (concrete floor, bedded with straw, 16 m²) and outdoor paddock area (100 m²). The trial started when pigs had 68±8 kg BW and 157±6 days of age. Two diets were formulated with equivalent ingredients and composition. For ECO diet the ingredients used were ecological. Group ECO received a diet with 12.4 MJ metabolisable energy (ME) per kilogram and 12.9% CP and group CON a diet with 12.7 MJ ME/kg and 13.6% CP. Feed distribution was limited to 3.5 kg per pig daily. In line with the rules for organic production, ECO pigs were additionally given alfalfa hay ad libitum. After 73 days on trial, the pigs were slaughtered and carcass, meat and fat quality was evaluated. Meat quality traits (pH, colour, water holding capacity), fatty acid composition, lipid and protein oxidation, collagen content and solubility were analysed in longissimus lumborum (LL) muscle. Fatty acid composition, lipid oxidation, and vitamins A and E concentrations were determined in backfat. There were no significant differences in growth rate and carcass traits between ECO and CON pigs, however, ECO pigs tended (P<0.10) to have higher daily gain and lower dressing percentage, higher (P<0.001) pH 45 min and lower (P<0.01) pH 24 h postmortem, affecting (P<0.10) also water holding capacity and objective colour parameters (P<0.05) of LL muscle. There were no differences in intramuscular fat (IMF) content of LL muscle, however, IMF of ECO pigs had lower (P<0.05) proportion of saturated and higher (P<0.01) proportion of monounsaturated fatty acids accompanied by higher (P<0.001) values of thiobarbituric reactive substances (TBARS). In backfat, ECO pigs showed lower (P<0.05) vitamin E content, higher (P<0.001) TBARS, higher (P<0.01) degree of unsaturation (percentage of polyunsaturated fatty acids), and also higher (P<0.05) vitamin A concentration than CON pigs, which can be related to alfalfa hay supplementation of ECO pigs. In brief, organic rearing of Krškopolje pigs did not affect performances but had an effect on meat and fat quality.     

Effects of dietary CP and amino acid restriction on the growth dynamics of organs and body components in entire male,castrated and female pigs

The optimized use of dietary nutrients and the accurate knowledge of the growth dynamics of body components is important for efficient pig production. This study aimed at evaluating the growth of carcass components and organs of Swiss Large White pigs from birth to 140 kg BW depending on the CP and amino acid (AA) supply. A total of 66 entire males (EM), 58 castrates (CA) and 66 female (FE) pigs were used. From 20 kg BW onwards, they had either ad libitum access to a control (C) or a diet (LP) with 20% lower CP, lysine, methionine + cystine, threonine and tryptophan content compared to C. The weight of organs, primal cuts and external fat were recorded in eight EM and eight FE; at 10 kg BW, on two EM, CA and FE each, and at 20 kg BW, on eight pigs from each sex. From 40 to 140 kg BW at 20 kg intervals, measurements were recorded on four pigs per sex and dietary treatment. The weight of each component was related to empty body (EB) using allometric regressions. Kidneys were heavier (P<0.05) in C- than LP-pigs and in EM than CA and FE. Above 21 kg EB weight, growth rate of LP-FE overpassed (P<0.05) the one of C-pigs. Consequently, LP-FE had heavier (P<0.05) lean cuts than C-pigs in the finisher period. However, LP-CA and LP-EM displayed lower (P<0.05) weights and growth rates of the lean cuts than C-CA and C-EM. Shoulder and loin weights and growth rates were reduced (P<0.05) in LP-pigs when compared to C-pigs. Growth rates of the ham were greater (P<0.05) in LP-FE than C-FE, whereas in LP-EM and LP-CA they were lower (P<0.05) than their C-counterparts. Total amounts of subcutaneous fat, backfat, ham fat and shoulder fat were lower (P<0.05) in C- than LP-pigs. The total amount of subcutaneous fat, backfat and shoulder fat of C-CA was, regardless of diet, greater (P<0.05) than of C-FE. In the LP group, this difference was even more pronounced. The amount of deposited ham fat was greater (P<0.05) in LP-CA than LP-FE, but not in C-CA v. C-FE. Differences in kidney weights suggested a greater nitrogen clearance required in C-pigs. Overall, dietary restriction and sex did not affect all body parts to the same extent. This study further suggests the possibility to reduce the CP and AA supply in FE without compromising the yield of primal lean cuts or increasing the amount of subcutaneous fat.     

Finishing season and feeding resources influence the quality of products from extensive-system Gascon pigs. Part 2: muscle traits and sensory quality of dry-cured ham

The quality of pork products from local breeds in extensive systems depends, among other things, on pig production. In particular, the variability in climatic conditions and feeding resources may influence the properties of tissues at slaughter and the quality of pork and processed products. The present study (part 2) was part of a larger project that assessed the influence of the finishing season and feeding resources on carcass and tissue traits and the quality of meat and dry-cured ham from Gascon pigs in an extensive system. Following the specifications of the Protected Designation of Origin “Noir de Bigorre”, castrated Gascon males were reared on rangelands (grassland and forest areas) and received a supplementary diet from 5 to 6 months of age until slaughter at a minimum of 12 months and ca. 170 kg BW. Three finishing seasons were considered: Winter (n = 18), Spring (n = 22) and Autumn (n = 23). To estimate the specific effects of season on quality traits and avoid bias due to effects of genes known to influence these traits, polymorphisms in the RYR1, PRKAG3, MC4R and LEPR genes were included in the analysis models. Compared to Winter pigs, Spring and Autumn pigs had higher ultimate pH in the semimembranosus and gluteus medius (GM) muscles, lower meat lightness (P < 0.05) and tended to have higher GM intramuscular fat (IMF) content (P < 0.10). They also had higher GM contents of saturated, monounsaturated and polyunsaturated fatty acids (FAs) than Winter pigs (P < 0.05). Spring pigs had the lowest n-6:n-3 polyunsaturated FA ratio and the highest GM α-tocopherol content (P < 0.001), indicating pig grazing. The finishing season did not influence the processing yield of dry-cured hams (24-month process). Within each seasonal group, ten hams selected for genetic variability and IMF content were analyzed by a trained sensory panel. The season did not modify the appearance or odor, but influenced texture and taste. Hams from Winter and Spring pigs had higher tenderness and melting fat scores than hams from Autumn pigs (P < 0.01). Hams from Spring pigs had higher taste intensity and salty taste (P < 0.01) but lower positive tastes (e.g. fruits, forest) than hams from the other groups. Overall, finishing season had moderate effects on ham sensory traits. Furthermore, our results reveal high redness, tenderness, taste and odor intensity, and low rancid flavor of hams from Gascon pigs produced in an extensive system.     

Effects of sex and dietary lysine on performances and serum and meat traits in finisher pigs

A total of 160 Duroc×(Landrace×Large White) pigs, 50% barrows and 50% gilts, of 28.3±4.52 kg of BW were used to study the effect of lysine (Lys) restriction in the finisher period, on growth performances and serum and carcass and meat quality traits. The grower diet (from 30 to 90 kg BW) was slightly Lys-restricted (7.8 g standardised ileal digestible (SID) Lys/kg) in accordance with results from a previous trial. During the finisher period (90 to 130 kg BW), four experimental diets with decreasing SID Lys contents (6.3, 5.6, 4.2 and 3.2 g/kg) were tested. Each of the eight treatments (two sexes×four levels of Lys) was replicated five times. Each replicate was a pen with four pigs allocated together. When animals achieved 129±2.59 kg were slaughtered and carcass and meat characteristics were evaluated. No significant interaction sex×diet was found. During the finisher period, barrows grew faster (P<0.001) and ate more feed (P<0.001) but tended to be less efficient (P=0.055) than gilts. The Lys restriction affected linearly (P<0.001) all productive performance traits; daily BW gain and feed intake decreased and feed conversion ratio increased. Also, the concentration of serum urea at slaughter tended to be higher in barrows than in gilts (P=0.065) and was reduced quadratically by the restriction of Lys in feed (P<0.001). Carcasses from barrows had higher backfat thickness (P<0.01) and lower weight of main trimmed lean cuts (ham+shoulder+loin; P<0.05) than those from gilts. The Lys restriction during the finisher period decreased carcass yield (quadratic; P<0.001) and the weight of major cuts (linear; P<0.001). Sex and diet had limited effect on meat characteristics; the Lys restriction decreased quadratically the proportion of protein (P<0.01) and increased linearly the intramuscular fat (IMF) content (P<0.001). We can conclude that dietary Lys restriction during finisher period in pigs impaired growth performances and was not successful to increase the carcass fat deposition, although it could have positive effects on IMF proportion of pork.     

Finishing season and feeding resources influence the quality of products from extensive-system Gascon pigs. Part 1: Carcass traits and quality of fresh loin

Consumers perceive pork products from local breeds reared in extensive systems positively because of their specific quality properties and regional identity. The sensory, nutritional and technological qualities of these products depend, among other things, on pig production, especially its climatic conditions and the availability of feed resources, which can influence traits of muscle and fat tissue. The present study (part 1) was part of a larger project that assessed the influence of the finishing season and feeding resources on carcass and tissue traits and the quality of meat and dry-cured ham from Gascon pigs in an extensive system. Following the specifications of the Protected Designation of Origin “Noir de Bigorre”, castrated Gascon males were reared on rangelands (grassland and forest areas) and received a supplementary diet from 5 to 6 months of age until slaughter at a minimum of 12 months of age and ca. 170 kg live weight. Three finishing seasons were considered as follows: Winter (n = 18), Spring (n = 22) and Autumn (n = 23). To estimate specific effects of season on productive and quality traits and avoid bias due to effects of genes known to influence these traits, polymorphisms in the RYR1, PRKAG3, MC4R and LEPR genes were included in the analysis models. The finishing season did not influence growth rate. Compared to Winter pigs, Spring and Autumn pigs had slightly lower carcass fatness (P < 0.05), higher ultimate pH and redder and darker color of the Longissimus muscle (LM) (P < 0.01). Loin drip loss was low overall, but was higher for Spring pigs, whereas cooking loss and shear force were similar among seasons. Spring pigs tended to have the lowest LM lipid content, whereas LM myoglobin content remained unaffected. Autumn pigs had lower potential of lipid oxidation in LM than Winter and Spring pigs (P < 0.01), but muscle metabolic traits assessed via glycolytic and oxidative enzyme activities did not differ among seasons. The finishing season modified the backfat fatty acid (FA) profile, with a lower polyunsaturated FA percentage in Autumn pigs than Winter or Spring pigs (P < 0.001), even though the saturated and monounsaturated FA percentages did not differ. In particular, Spring pigs had the lowest n-6:n-3 and C18:2:C18:3 ratios (P < 0.001), as a result of grazing. Overall, Spring and Autumn finishing seasons seem more favorable to technological and sensory pork attributes, with an additional positive effect of Spring finishing on pork nutritional value.     

Influence of rearing system,diet and gender on performance,carcass traits and meat quality of Polish Landrace pigs

Forty-eight Polish Landrace pigs (initially 32.43 ± 0.70 kg live weight) were assigned to a 2 × 2 × 2 factorial arrangement in order to assess the effects of the rearing system (outdoor v. indoor), diet (with corn grain silage v. without corn grain silage) and gender (barrows v. gilts) on performance, carcass traits, meat quality and intramuscular collagen (IMC) characteristics. During the trial period of 14 weeks, each group was housed in a pen of 12 m², and the outdoor-reared animals had access to a paddock of 24 m². Pigs were fed a diet computed according to standard requirements and supplied on a basis of 9% of metabolic weight (live weight^0.75). Pigs were slaughtered at 110.69 ± 0.85 kg. The rearing system did not significantly affect growth, hot and cold dressing, meat quality of m. longissimus lumborum or IMC. Outdoor pigs had less (P < 0.05) backfat thickness, slightly higher (P = 0.082) lean percent and a meat with lower pH and fat than the conventional system. In light of these results, alternative pig rearing systems with indoor space and free outdoor access could be an interesting production system for the pigs. Compared with the pigs fed diets with corn grain silage, those fed diets without corn had higher (P < 0.05) lean, ham percentage and IMC content, lower (P < 0.05) neck percentage but similar main tissue components of the ham and meat quality. Compared with the gilts, barrows were fatter and showed a meat with different physico-chemical traits, which was slightly more tender and had similar IMC properties.     

The effect of immunocastration and a diet based on granulated barley on growth performance and carcass,meat and fat quality in heavy gilts

A total of 48 Duroc×(Landrace×Large White) gilts of 33.2 kg BW were used to investigate the influence of immunocastration and diet on growth performance and carcass, meat and fat quality. Four treatments were arranged factorially (2×2) with two sexes (immunocastrated gilts: IG v. entire gilts: EG) and two dietary treatments (a commercial feedstuff as control v. granulated barley as a single major ingredient) provided during the finishing period (from 103 to 126 kg BW). There were four replicates of three pigs per treatment. At the end of the trial, the IGs grew faster (P<0.05) and ate more feed (P<0.05) than the EGs. Carcasses from the IGs had thicker backfat depth than those from the EGs (P<0.01) and carried out a lower percentage of rejected carcasses (P<0.05) at slaughterhouse owing to lack of fat. Meat from the IGs tended to have higher intramuscular fat (IMF) content in the Longissimus thoracis (LT) muscle than that from the EGs (P=0.09). In addition, immunocastration increased the total saturated fatty-acid proportion in subcutaneous fat and IMF (P<0.001) and decreased the total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) percentages in subcutaneous backfat (P<0.05 and P<0.001, respectively) and in IMF (P<0.01 and P=0.06, respectively). The use of a diet based on granulated barley during the finishing period had no effect on growth performance but tended to increase IMF content in the LT muscle (P<0.06), and increased MUFA (P<0.05) and decreased PUFA (P<0.01) proportions in omental fat. It is concluded that immunocastration of gilts intended for dry-cured ham industry improved some aspects of growth performance and carcass and meat quality, whereas granulated barley had scarce effect on productive traits and fatty-acid profile but tended to improve IMF content.     

Effects of grain type and conditioning temperature during pelleting on growth performance,ruminal fermentation,meat quality and blood metabolites of fattening lambs

Ruminants can tolerate moderate concentrations of dietary tannin, making it feasible to replace corn with sorghum in ruminant diets; however, conditioning temperature of pelleted total mixed ration (PTMR) greatly affects nutrient digestibility. The objective was to determine effects of grain type and conditioning temperature during pelleting on growth performance, ruminal fermentation, meat quality and blood metabolites of fattening lambs. This was a 2 × 3 factorial study, with corn and sorghum and three conditioning temperatures (65, 75 and 85 °C) in a randomized complete design, with 36 lambs (120 ± 10.2 d and 24.9 ± 3.3 kg) grouped by weight and randomly allocated. The resulting six PTMRs were referred to as 65-S, 75-S and 85-S for sorghum-based diets, and 65-C, 75-C and 85-C for corn-based diets, for low, medium and high pelleting temperatures, respectively. There was no grain type × conditioning temperature (Grain × Temp) interaction on growth performance and apparent nutrient digestibility. Furthermore, grain type did not affect DM intake (DMI), average daily gain (ADG) or feed conversion ratio (FCR) of fattening lambs. Pelleting at 75 °C improved ADG (P < 0.03) and FCR (P < 0.02) of fattening lambs compared to other temperatures. There was a Grain × Temp interaction (P < 0.01) on ruminal pH (lowest in lambs fed 75-S). There tended (P = 0.07) to be a Grain × Temp interaction for total volatile fatty acid (VFA), and there were Grain × Temp interactions for molar proportions of acetate (P < 0.04), butyrate (P < 0.03) and branch-chained VFA (P < 0.01). Lambs fed sorghum-based PTMR had greater molar proportion of propionate (P < 0.03) and lower acetate to propionate ratio (A:P, P < 0.04). Lambs fed sorghum-based PTMR had higher plasma concentrations of urea nitrogen (N) (P < 0.03), glucose (P < 0.01) and alkaline phosphatase (P < 0.05), whereas other blood metabolites were not affected by treatments. There were Grain × Temp (P < 0.03) interactions for color coordinates of longissimus and mid-gluteal muscle. Lambs fed sorghum-based PTMR had lower (P < 0.01) dressing percentage and meat quality than those fed corn-based PTMR. We concluded that sorghum can replace corn in lamb diets without compromising growth performance and feed efficiency; furthermore, feeding sorghum vs corn improved rumen fermentation, with reduced A:P ratio and enhanced N and glucose utilization. Finally, pelleting at 75 °C increased feeding value of either sorghum- or corn-based PTMR for fattening lambs.     

Protein retention,growth performance and carcass traits of individually housed immunocastrated male- and female- and surgically castrated male Iberian pigs fed diets of increasing amino acid concentration

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 no significant sex group × dietary CP interactions. Iberian IC males grew at higher rate, deposited more protein, and more efficiently, than Iberian SC males before the second vaccination against GnRH. Iberian IC females showed similar growth performance to SC males and intermediate protein deposition efficiency between IC and SC males. Despite the higher growth performance, protein deposition rate, and efficiency of protein deposition of IC males v. SC males, no significant differences in amino acid requirements were detected between them.     

Old breeds,new solutions? Effects of two different traditional sire breeds on skin lesions,tail lesions,tail losses,performance and behaviour of rearing pigs

Some studies indicated a relationship between modern, fast-growing, lean-meat-producing hybrid pigs and the occurrence of tail-biting, one of the major issues of conventional pig husbandry. Therefore, this study investigated the effects of different local, traditional sire breeds on the behaviour and performance of rearing pigs. Between December 2019 and November 2020, a total of 1 561 piglets were weaned from hybrid sows (Bundes Hybrid Zucht Programm (BHZP) Landrace × BHZP Large White) that were paired with either Swabian-Hall (SH), Bentheim Black Pied (BB) or BHZP-Piétrain (Pi) boars. Tails of the piglets were left intact (43.5%) or docked (56.5%), and male piglets were castrated. Piglets were conventionally reared on fully slatted plastic flooring in mixed-sex groups. Starting one day after weaning, skin lesions were scored once per pig, and tail lesions and losses were scored weekly until the end of rearing. The average daily gain was documented for the suckling and rearing period. The activity behaviour of eight focal pens was analysed using video recordings. Differences between modern and traditional breeds were found in this study for so-called aggressive and non-aggressive biting pronounced by skin and tail lesions and tail losses. Significantly fewer BB pigs had severe skin lesions on the front body than SH or Pi pigs (P < 0.05). Additionally, piglets that were classified as light (<5.6 kg) at weaning showed skin lesion scores of 0 more often than piglets that were classified with a medium (≥5.6–≤8.3 kg) or heavy (>8.3 kg) weaning weight (P < 0.05). In the first half of the rearing period, significantly more BB pigs were assessed as having no tail lesions and tail losses than SH and Pi pigs (P < 0.01). However, these differences disappeared in the second half of rearing. Either docked or undocked Pi pigs had significantly higher average daily gains than SH and BB pigs (P < 0.05). The activity of the focal pens was not influenced by the sire breed or tail lesion class, which might be due to the limited sample size of eight pens. To conclude, the use of the traditional sire breed BB has the potential to reduce injurious behaviour in the offspring. However, adjustments to the housing and feeding should be taken to further reduce the incidence of tail lesions and losses and to enhance performance.     

Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs

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.     

Mild Calorie Restriction Induces Fat Accumulation in Female C57BL/6J Mice

This study investigated the effects of mild calorie restriction (CR) (5%) on body weight, body composition, energy expenditure, feeding behavior, and locomotor activity in female C57BL/6J mice. Mice were subjected to a 5% reduction of food intake relative to baseline intake of ad libitum (AL) mice for 3 or 4 weeks. In experiment 1, body weight was monitored weekly and body composition (fat and lean mass) was determined at weeks 0, 2, and 4 by dual energy X‐ray absorptiometry. In experiment 2, body weight was measured every 3 days and body composition was determined by quantitative magnetic resonance weekly, and energy expenditure, feeding behavior, and locomotor activity were determined over 3 weeks in a metabolic chamber. At the end of both experiments, CR mice had greater fat mass (P < 0.01) and less lean mass (P < 0.01) compared with AL mice. Total energy expenditure (P < 0.05) and resting energy expenditure (P < 0.05) were significantly decreased in CR mice compared with AL mice over 3 weeks. CR mice ate significantly more food than AL mice immediately following daily food provisioning at 1600 hours (P < 0.01). These findings showed that mild CR caused increased fat mass, decreased lean mass and energy expenditure, and altered feeding behavior in female C57BL/6J mice. Locomotor activity or brown adipose tissue (BAT) thermogenic capacity did not appear to contribute to the decrease in energy expenditure. The increase in fat mass and decrease in lean mass may be a stress response to the uncertainty of food availability.     

Influence of production system in local and conventional pig breeds on stress indicators at slaughter,muscle and meat traits and pork eating quality

Sensory quality of pork is a complex phenotype determined by interactions between genetic and environmental factors. This study aimed at describing the respective influences of breed and production system on the development of pork quality. Plasma stress indicators and Longissimus muscle (LM) composition, physicochemical and sensory quality traits were determined in two contrasted breeds – the conventional Large White (LW, n=40) and the French local Basque (B, n=60). Pigs were reared in either a conventional (C; n=20 per breed), alternative (A; sawdust bedding and outdoor area, n=20 per breed) or extensive system (E; free-range, n=20 B). All the pigs from A and C systems were slaughtered at the same slaughterhouse, whereas B pigs from the E system were slaughtered at a local commercial abattoir. Major breed differences were found for almost all traits under study. LM from B pigs exhibited higher lipid, lower water and collagen concentrations, as well as lower collagen thermal solubility (P<0.001). Although plasma stress indicators at slaughter did not differ between breeds, except lower (P<0.05) lactate levels in B pigs, they exhibited higher LM pH1 and pHu values, and lower meat lightness, hue angle, water (drip, thawing and cooking) losses, glycolytic potential and shear force. Sensory analyses highlighted higher redness, marbling, tenderness, juiciness and flavour scores (P<0.01) of meat from B compared with LW pigs. Within both LW and B breeds, compared with C, the A system did not (P>0.05) influence plasma stress indicators, LM chemical composition and physicochemical or sensory traits of pork. In contrast, within the B pigs, the E system affected the meat quality more. Lower plasma cortisol levels (P<0.05), but higher plasma lactate, creatine kinase and lactate dehydrogenase activities, and more skin lesions (P<0.05), indicating higher muscular activity during pre-slaughter handling, were found in pigs produced in the E compared with the C system. E pigs exhibited higher meat pH1 and pHu values and shear force (P<0.01) and exhibited lower lightness, hue angle and drip and thawing losses (P<0.01) compared with the C pigs, whereas LM lipid, protein or collagen concentrations were not affected. Regarding sensory traits, the E system produced redder meat, but did not impact the eating quality of pork. Altogether, this study demonstrates that differences in meat quality between B and LW breeds can be modulated by extensive pig production system.     

Effect of ractopamine and conjugated linoleic acid on performance of late finishing pigs

The dietary inclusion of feed additives to improve the carcass characteristics of the final product is of great importance for the pork production chain. The aim of our study was to evaluate the effects of the association of ractopamine (RAC) and conjugated linoleic acid (CLA) on the performance traits of finishing pigs during the last 26 days prior to slaughter. In total, 810 commercial hybrid barrows were used. Animals were distributed among treatments according to a randomised block design in a 3 × 3 factorial arrangement, with three RAC levels (0, 5 or 10 ppm) and three CLA levels (0, 0.3 or 0.6%). Pigs fed the diet with 5 ppm RAC had higher average daily feed intake (ADFI) (2.83 kg; P < 0.05) when compared with those fed 10 ppm RAC and the control diet (2.75 and 2.74 kg, respectively). Lower ADFI values (P < 0.01) were observed with the diets containing CLA compared with the control diet with no CLA (2.73 and 2.75 v. 2.85 kg/day, respectively). The average daily weight gain of pigs fed 5 and 10 ppm RAC was +148 and +173 g/dayhigher (P < 0.001), respectively, than those fed the control diet. Dietary RAC levels influenced (P < 0.001) feed conversion ratio (FCR), which was reduced as RAC levels increased, with the pigs fed 10, 5 and 0 ppm RAC presenting FCR values of 2.57, 2.71 and 3.05, respectively. FCR also improved (P < 0.05) with the inclusion of 0.6% CLA relative to the control diet (2.70 v. 2.84, respectively). There was a significant interaction between CLA × RAC levels (P < 0.01) for final BW, loin eye area (LEA) (P < 0.05) and backfat thickness (BT) (P < 0.05). The treatments containing 10 ppm RAC + 0.6% or 0.3% CLA increased LEA and reduced BT. In conclusion, the level of 10 ppm inclusion of RAC increased the overall performance parameters of pigs and therefore improved production efficiency. The combined use of RAC and CLA promoted a lower feed conversion ratio as well as better quantitative carcass traits, as demonstrated by the higher LEA and lower BT. The dietary inclusion of CLA at 0.3% improved feed efficiency, however, without affecting LEA or BT yields.     

Effects of resistant starch on behaviour,satiety-related hormones and metabolites in growing pigs

Resistant starch (RS) has been suggested to prolong satiety in adult pigs. The present study investigated RS-induced changes in behaviour, satiety-related hormones and metabolites in catheterized growing pigs to explore possible underlying mechanisms for RS-induced satiety. In a cross-over design with two 14-day periods, 10 pigs (initial BW: 58 kg) were assigned to two treatments comprising diets containing either 35% pregelatinized starch (PS) or 34% retrograded starch (RS). Diets were isoenergetic on gross energy. Pigs were fed at 2.8× maintenance. Postprandial plasma response of satiety-related hormones and metabolites was measured at the end of each period using frequent blood sampling. Faecal and urinary energy losses were measured at the end of each period. Behaviour was scored 24 h from video recordings using scan sampling. Energy digestibility and metabolizability were ~6% lower in RS compared with PS diet (P<0.001), and metabolizable energy (ME) intake was ~3% lower in RS-fed than in PS-fed pigs (P<0.001). RS-fed pigs showed less feeder-directed (P=0.001) and drinking (P=0.10) behaviours than PS-fed pigs throughout the day. Postprandial peripheral short-chain fatty acid (SCFA) levels were higher in RS-fed than in PS-fed pigs (P<0.001). Postprandial glucose and insulin responses were lower in RS-fed than in PS-fed pigs (P<0.001). Triglyceride levels were higher in RS-fed than in PS-fed pigs (P<0.01), and non-esterified fatty acid levels did not differ between diets (P=0.90). Glucagon-like peptide-1 (GLP-1) levels were lower in RS-fed than in PS-fed pigs (P<0.001), and peptide tyrosine tyrosine (PYY) levels did not differ between diets (P=0.90). Blood serotonin levels were lower (P<0.001), whereas monoamine oxidase activity (P<0.05) and tryptophan (P<0.01) levels were higher in RS-fed than in PS-fed pigs. Despite a lower ME intake, RS seemed to prolong satiety, based on behavioural observations. Possible underlying mechanisms for RS-induced satiety include increased 24 h plasma SCFA levels, and decreased postprandial glucose and insulin responses. GLP-1 and PYY seemed not to play a role in RS-induced satiety. Low blood serotonin levels in RS-fed pigs suggested a difference in intestinal serotonin release between treatments. Increased postprandial plasma triglyceride levels corresponded with increased SCFA levels, but it is unclear whether triglycerides may have signalled satiety in RS-fed pigs.     

Effect of feed restriction on the performance and behaviour of pigs immunologically castrated with Improvac®

For centuries, entire male pigs have been castrated to reduce the risk of boar taint. However, physical castration of pig is increasingly being questioned with regard to animal welfare considerations. Immunization against gonadotrophin releasing hormone (GnRH) provides an alternative to physical castration. Using the currently available commercial product (Improvac®; Pfizer Animal Health), a two-dose regimen of a GnRH vaccine is administered. After the second vaccination, a substantial increase in feed consumption has been reported, which may be associated with increased body fatness and decreased feed efficiency when compared with unvaccinated entire male pigs. The aim of the present study was to investigate the effect of a feed restriction on these traits and on the behaviour of 120 group-housed entire males (five pigs/pen) vaccinated against GnRH. The first vaccination was performed at 62 days of age and the second (V2) at 130 days of age. Pigs were slaughtered in two batches 4 to 5 weeks after V2. They were either offered feed ad libitum over the 22 to 114 kg BW range (AL treatment) or ad libitum up to a maximum of 2.50 (R2.50 treatment) or 2.75 kg/day per pig (R2.75 treatment). Behavioural observations and skin lesion scoring were conducted 1 week before V2, and 1 and 3 weeks after V2. At slaughter, the volumetric lean meat content was measured using an X-ray computed tomography scanner. Between V2 and slaughter, the average feed intakes for the R2.75 and R2.50 treatments were 15% and 22% lower than the average AL feed intake (3.20 kg/day), respectively. Feed restriction was associated with a reduced average daily gain after V2 (846, 932 and 1061 g/day in the R2.50, R2.75 and AL groups, P < 0.01) but had no effect on the feed conversion ratio (3.00 kg feed/kg BW gain on average, P = 0.62). No difference was observed in the lean meat content (71.8%, 70.7% and 70.4% in the R2.50, R2.75 and AL groups, P = 0.14), despite a reduced backfat thickness measured in restrictively fed pigs (12.0, 13.0 and 13.6 mm in the R2.50, R2.75 and AL groups, P < 0.01). Higher skin lesion scores were observed 3 weeks after V2 in R2.50 and R2.75 pigs than in the AL ones (scores 33.4, 27.7 and 25.5, respectively, P = 0.04). These results, combined with an unimproved feed efficiency and no marked change in carcass characteristics, suggest that immunologically castrated pigs should not be restrictively fed during the late finishing period.