Effect of feed restriction on hormones, performance, carcass traits, and meat quality in immunocastrated pigs

Feeding strategy in organic pig farming as a lever to improve various quality dimensions of pork

Since 2022, European specifications for organic pig farming have evolved to distribute 100 % organic feed and to reinforce the link to the soil with feed resources that should primarily be obtained from the farm or the same region. Feeding strategy acts as a lever to improve various quality dimensions of organic (as well as conventional) pork, including intrinsic dimensions (carcass composition, nutritional, organoleptic, technological, sanitary qualities) and extrinsic dimensions related to animal farming (image). Diet may also influence the risk of undesirable odours or flavours that may be found in pork from non-castrated male pigs. This study aimed at evaluating the effects of a specific feeding strategy on several quality dimensions of organic meat from non-castrated male pigs. The experiment was conducted with 77 organic non-castrated male pigs (Piétrain NN × Large White) reared according to organic specifications and distributed in two batches. Within litters, male littermates were allocated at around 33 kg of live weight to either a Control group which received a Control feed (C) corresponding to the organic specifications or in a Bio+ group which received an organic test feed based mainly on French raw materials and which contained more fibres (faba bean and access to forages) and omega-3 fatty acids (linseed, camelina). All pigs were reared in the same building on deep straw bedding (1.3 m2/pig) with free outdoor access (1.0 m2/pig) using one pen per experimental group. Pigs were fed ad libitum until slaughter at about 125 kg live weight. Average daily gain, carcass weight and lean meat content did not differ significantly between C and Bio+ pigs. Compared to C, Bio+ pigs had higher (P < 0.05) ultimate pH in the loin (Longissimus muscle) and ham (Gluteus medius, and Semimembranosus) muscles, associated with a lower Longissimus muscle glycolytic potential (P < 0.001). Loin and ham meat from Bio+ vs. C pigs was lighter (P < 0.05) and had a more intense red colour (P < 0.10). The Bio+ strategy led to a lower Longissimus muscle n-6:n-3 fatty acid ratio (P < 0.001), indicating an improvement in pork nutritional value. Backfat skatole concentration was lower in Bio+ than in C pigs whereas backfat androstenone was higher in Bio+ than in C pigs (P < 0.05). Altogether, we demonstrated that the Bio+ strategy had positive impacts on several qualities of organic pork from non-castrated male pigs.

The effects of different immunocastration protocols on meat quality traits and boar taint compounds in male Bísaro pigs

Immunocastration can be an alternative to surgical castration in Bísaro pigs when there is a need to keep animals on the farm until at least 8 months old. As an autochthonous breed, some particularities must be addressed when doing immunocastration, for which 3 different protocols were tested and two control groups were made with surgically castrated males (SC) and boars (Bo). Two protocols were made in prepubertal pigs, with two (E2) and three inoculations (L3) in the first cycle, and another in adults (A2) with only two inoculations. Physicochemical parameters and boar taint compounds quantification and sensory analysis of the meat from the studied pigs were assessed. Immunocastration provided intermediate values between surgically castrated pigs and entire males, with low levels of boar taint compounds. The L3 group provided closer results to SC, which was also corroborated by the sensory analysis. Although the other two protocols had no significant differences with Bo, there was a positive tendency towards them. As is, the L3 protocol was promising as a good alternative to surgical castration, maintaining the characteristic attributes of the Bísaro pig meat.

Change in fat skatole and indole content in lambs switched from a concentrate-based diet indoors to alfalfa grazing for various durations before slaughter

Meat from lambs fattened on alfalfa is at risk of excessive pastoral flavours due to high levels of in-fat volatile indolic compounds (especially, skatole). Skatole has also been identified as a potential marker of interest for authenticating pasture-fed lamb meat. Here, we investigated the change in skatole and indole concentrations in kidney fat from lambs switched from an indoor-fed concentrate based diet to outdoor alfalfa grazing for various durations (0, 21, 42, 63 days) before slaughter. The study used a total of 219 lambs over 3 consecutive years. Kidney-fat skatole and indole concentrations increased from as early as 21 days on alfalfa, and then reached a plateau. Similarly, the proportion of lambs that had a kidney fat-skatole concentration above 0.15 μg/g liquid fat, a value that has been established as a sensory rejection threshold for pork, increased significantly from as early as 21 days on alfalfa and then reached a plateau. This value was reached or exceeded in a significant proportion of lambs fattened on alfalfa pastures (45.1%). However, skatole was not detected in kidney fat from 20 out of 164 alfalfa-fattened lambs (i.e., 12.2%) but was detected in 15 out of 55 concentrate-fed lambs (i.e., 27.3%). We thus conclude that while skatole content in kidney fat can inform on dietary changes made shortly before slaughter, it does not have the discrimination power needed to reliably authenticate pasture-fed lamb meat, let alone duration of finishing on pasture.

Metabolic Profile of Growing Immune- and Surgically Castrated Iberian Pigs Fed Diets of Different Amino Acid Concentration

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.

Male Reproductive Organ Weight: Criteria for Detection of Androstenone-Positive Carcasses in Immunocastrated and Entire Male Pigs

Immunocastration and rearing of entire males (EMs) are sustainable alternatives to surgical castration. However, these animal carcasses have variable risk of boar taint and should be identified at the slaughter line. We aimed to identify a simple and reliable indicator of androstenone-related boar taint by evaluating pelvic urogenital tract weight as a marker of boar-taint animals at the slaughter line. The pelvic urogenital tract, testes, and accessory sex glands of EMs and immunocastrates (ICs) were collected, dissected, and weighed, before colorimetric measurements of testicular tissue. Additionally, GnRH antibody titers and testosterone, androstenone, and skatole levels were determined. Our results showed that 81.8% of EMs had androstenone levels above the risk threshold (>0.5 µg/g fat; EM/A^high subgroup), whereas in ICs, the C/A^high subgroup with androstenone >0.5 µg/g fat accounted for only 4.3%. Androstenone levels correlated negatively with GnRH antibody titers and positively with testosterone levels and reproductive organ weights. Identification of ICs with androstenone levels above the threshold (IC/A^high subgroup) may be achieved via testes or pelvic urogenital tract weight measurements. However, in EMs, the latter is a more reliable parameter. A principal component analysis based on these variables and hierarchical clustering also distinguished the A^high from the A^low subgroup, irrespective of IC/EM. The findings highlight the possible use of pelvic urogenital tract weight along with testes weight as a simple, reliable, and efficient morphometric indicator for identifying androstenone-positive carcasses of different sex categories.

Effects of feeding methods on growth and slaughter performance, blood biochemical indices, and intestinal morphology in Minxinan black rabbits (Oryctolagus cuniculus)

Feed restriction after weaning is a common strategy used in commercial rabbit farms to improve feed efficiency, promote health, and reduce mortality. However, few studies have investigated the feed restrictions of Minxinan black rabbits (Oryctolagus cuniculus). Thus, the effects of feed restriction on growth and slaughter performance, intestinal morphology, and blood biochemical indices of Minxinan black rabbits were evaluated in this study. Rabbits in group A (control group) had ad libitum intake, while those in feed restriction groups (groups B, C, and D) were restricted to 80% of the average daily feed intake (ADFI) of group A the day before. The rabbits in group B were fed once per day at 8:00 am. Rabbits in groups C and D were fed twice per day at 8:00 am (50%) and 4:00 pm (50%) and 8:00 am (30%) and 4:00 pm (70%), respectively. The experimental period lasted for 8 weeks. Compared to that in group A, the diarrhea rate of group C was significantly decreased (P < 0.05), and the ADFI, feed conversion ratio, abdominal fat weight, abdominal fat rate, total protein, albumin, globulin, alanine aminotransferase (ALT), low-density lipoprotein, and intestinal crypt depth of all feed restriction groups were significantly reduced (P < 0.01). Feed conversion ratio in group D was significantly better than that in groups B and C (P < 0.05). The efficiency index (EI) of groups C and D was higher than that of groups A and B (P < 0.01). Triglyceride levels in groups C and D were significantly lower than those in group A. The villus length to crypt depth of the duodenum and jejunum in group D was significantly higher than that in group A (P < 0.01). In conclusion, the following parameters can be improved by feed restriction: feed conversion ratio, diarrhea rate, abdominal fat rate, serum ALT, lipid indices and intestinal health of Minxinan black rabbits, and the EI of the farm. Feeding twice per day, 30% at 8:00 am and 70% at 4:00 pm, had the best comprehensive effects.

Comparison of the meat quality and fatty acid profile of muscles in finishing Xiangcun Black pigs fed varied dietary energy levels

To study the effects of dietary energy level on the meat quality of different muscles in finishing pigs, 400 Xiangcun Black pigs (BW = 79.55 ± 4.77 kg) were randomly assigned to 5 treatments with varied calculated digestive energy (DE) at 3,050, 3,100, 3,150, 3,200 and 3,250 kcal/kg, respectively. Each treatment had 8 replicates with 10 pigs per replicate. Meat quality, amino acid and fatty acid composition were tested in this study. No differences in average daily gain, average daily feed intake or feed-to-gain ratio (P > 0.05) were observed among dietary treatments. Glycogen concentrations of longissimus dorsi (LD) muscle in DE3150 was higher than those in other groups (P < 0.05). The crude fat concentration of biceps femoris (BF) muscle in DE3250 tended to be higher than that in DE3150 and DE3100 groups (P < 0.05). Pigs in DE3250 and DE3200 had higher fiber density and smaller cross-sectional area of BF muscle than those in DE3150 (P < 0.05). Pigs in DE3150 had the highest Cu concentration in LD muscle compared with those in DE3200, DE3250 (P < 0.05). The C16:1 proportion of LD muscle was lower (P < 0.01) and C20:1 was higher (P < 0.05) in DE3050 than that in the other dietary treatments. The C18:3n6 and C20:3n6 proportions of BF muscle in DE3150 were higher than those in DE 3050, DE3200 and DE3250 (P < 0.05). For LD muscle, mRNA expressions of type I and IIa MyHC in group DE3150 were higher than other treatments (P < 0.01). The LD muscle in DE3150 expressed higher PPARd than in other groups (P < 0.01). Pigs in DE3100 expressed higher FOX1 than in DE3200 and DE3250 (P < 0.05). Sterol-regulatory element binding proteins (SREBPa) mRNA expression decreased linearly when dietary energy level increased in BF muscle (P < 0.01). In conclusion, a 200 kcal/kg decrease in digestible energy for 4 consecutive weeks did not affect growth performance of Xiangcun Black pigs. Furthermore, LD and BF muscle respond differently to dietary energy level, and meat quality was improved by the medium energy level during the finishing phase.

Comparison of Global Metabolite for Growing Pigs Fed at Metabolizable Energy Requirement for Maintenance

Though the energy requirement for maintenance is an important part of net energy system, little is known of the metabolic characteristics of maintenance energy expenditure. This study was investigated the effect of feeding level at metabolizable energy requirement for maintenance (FLM) on plasma metabolites in growing pigs. Ten barrows (22.5 ± 0.5 kg BW) were kept in metabolism crates and catheterized in the precaval vein during adaptation period. Pigs were fed a corn-soybean meal diet at 782 kJ ME/kg BW^0.6·d⁻¹ during d 1 to 8 and then were refeeding at 2,400 kJ ME/kg BW^0.6·d⁻¹ on d 9. Plasma samples of each pig were collected by catheter on the morning of d 1, 3, 5, 7, 9, and 10, respectively, for metabolomics testing. Results showed that the concentration of plasma urea nitrogen decreased under FLM (p < 0.01) and increased significantly after refeeding (p < 0.01). The concentration of total cholesterol, high-density lipoprotein, low-density lipoprotein, and albumin in plasma were decreased significantly after refeeding (p < 0.01). Eleven identified compounds were up-regulated and six ones were down-regulated under FLM. In conclusion, the energy metabolism of growing pigs was relatively stable after 4 days of feeding at FLM.

Reduced Use of Nitrites and Phosphates in Dry-Fermented Sausages

Given consumer demand for foods with fewer artificial additives, the objective of this study was to investigate the effects of reduced use of nitrites and phosphates on dry-fermented sausage quality. Four sausage formulations were prepared: (1) control (using standard procedure with 0.2% phosphates and 110 mg/kg sodium nitrite) and formulations with (2) 50% less sodium nitrite, (3) 50% less sodium nitrite and sodium ascorbate (225 mg/kg), and (4) with standard nitrite but no phosphates. Weight loss and pH evolution were monitored during processing. The color, physicochemical (including oxidation), rheological, and sensory properties were evaluated on the finished product, as well as mold growth and microbiological status. Compared to control, nitrite reduction was associated with increased surface mold growth, reduced (3.0–4.4%) processing loss, and slightly higher oxidation (1.7 μg/kg more malondialdehyde) but without affecting instrumental color. The simultaneous addition of ascorbate reduced oxidation and improved color stability. The formulation without the phosphates resulted in increased oxidation (3.4 μg/kg more malondialdehyde) and changes in the instrumental color. The observed changes were relatively unimportant, as neither of the tested formulations influenced sensory traits or compromised microbial safety, implying that they can be used in production without any harm or even with some benefits.

Effect of Castration Type and Diet on Growth Performance, Serum Sex Hormones and Metabolites, and Carcass Quality of Heavy Male Pigs

Simple Summary

Castration is indispensable in male pigs intended for the production of high-quality dry-cured ham; however, for welfare reasons, alternatives are being sought and, among them, immunocastration stands out. The literature shows that immunocastration might generate lower fat deposition than surgical castration, which is undesirable for the dry-curing process. Therefore, it would be interesting to confirm the impact of immunocastration in male pigs and to test feeding plans that benefit fatness. The aim of this trial was to assess the effect of type of castration (surgical vs. immunological) and diet (control vs. high energy vs. low crude protein and amino acids) on growth performance, serum sex hormones and metabolites, and carcass quality of male pigs destined for the Protected Designation of Origin Teruel ham. Although immunocastration improved productive performance, it reduced carcass fatness. Also, alternative diets to control improved the feed conversion ratio but did not influence carcass quality traits. In conclusion, under a quality point of view, surgical castration would be preferable over immunocastration for dry-cured ham production, and the use of moderately high-energy or low-crude-protein and -amino-acids diets from 80 to 137 kg of body weight would not provide improvements.

Abstract

A trial was carried out to study the effect of type of castration and diet on pigs destined for Teruel ham production, which is a Spanish protected designation of origin for dry-cured ham. A total of 144 Duroc × (Landrace × Large White) male pigs were used. Half of them were surgically castrated and the other half were immunocastrated with three doses at approximately 25, 58 and 79 kg of body weight. Furthermore, three diets (control vs. high energy vs. low crude protein-CP- and amino acids-AA) were tested from 80 to 137 kg of body weight. Growth performance, serum sex hormones and metabolites, and carcass quality were evaluated. Immunocastrated males grew faster and had better feed conversion ratio than surgically castrated males, but presented lower carcass fatness. Pigs fed the high-energy diet and the low-CP and -AA diet were more efficient at transforming feed into gain than those fed the control diet, but no effect was detected on carcass quality. In conclusion, surgically castrated males are preferable than immunocastrated males for Teruel dry-cured ham elaboration. Besides, a high-energy diet or a low-CP and -AA diet might improve productive performances, but does not provide any benefit in terms of carcass quality.

Effect of Changes in Dietary Net Energy Concentration on Growth Performance, Fat Deposition, Skatole Production, and Intestinal Morphology in Immunocastrated Male Pigs

Nutritional requirements of heavy immunocastrated (IM) pigs and therefore appropriate feeding strategies have not yet been determined. Thus, the effects of changes in dietary net energy (NE) content were studied in 41 IM pigs, fed ad libitum diets with low, medium, and high NE content (LNE, MNE, and HNE diets, with 8.5, 9.3, and 10.0 MJ NE/kg, respectively), from 84 days of age until slaughter at an average age of 172 days and an average body weight of 122.5 kg. In the period from 143 to 170 days of age, there was a tendency for a greater NE intake (p = 0.08) in pigs fed the HNE diet along with greater (p < 0.01) backfat gain. Dietary treatment affected carcass composition, as lower backfat thickness (p = 0.01) and lower area of fat over the longissimus muscle (p = 0.05) were observed in the LNE and MNE pigs. In addition, greater lean meat content (p = 0.04) was observed in the LNE pigs. Reducing the NE of the diet by replacement of cereals and soybean meal with high-fiber ingredients resulted in lower indole production in the ascending colon (p < 0.01) and greater skatole production (p < 0.01) in the cecum. Greater villus area, width, height and perimeter, crypt depth, and thickness of the intestinal mucosa in the jejunum, ileum, ascending colon, and descending colon were found in the LNE group (p < 0.01) than in the HNE group, while those in the MNE group was intermediate. Cell proliferation was not affected by dietary treatment (p > 0.05). The present results show that a reduction in dietary NE concentration lowers lipid deposition, without affecting performance or energy efficiency in IM pigs. This technique provides an advantage in terms of improved leanness, without affecting growth rate in IM pigs after immunization, which is particularly important when the backfat thickness is a determinant of carcass value and IM pigs are fattened to higher weights (e.g., in heavy pig production) or when a longer delay between immunization and slaughter is practiced.

Influence of Immunocastration and Diet on Meat and Fat Quality of Heavy Female and Male Pigs

Two experiments were carried out; one with female pigs and the other with male pigs destined for Teruel dry-cured ham production, to evaluate the effect of immunocastration (entire gilts-EG vs. immunocastrated gilts-IG and surgically castrated males vs. immunocastrated males-IM) and diet (control vs. high energy vs. low crude protein and amino acids) on meat quality and fat composition. Fifteen meat samples and eight fat samples of each treatment were analyzed in both experiments. In the case of males, six fat samples per treatment were analyzed to determine boar taint. Immunocastration is a good strategy in gilts intended for dry-cured ham production because improves meat composition; however, in males, immunocastration impairs the results of pork chemical composition compared with surgical castration. The IG presented a lower polyunsaturated/saturated fatty acids ratio than EG, improving fat technological quality. Diets had little effect on pork or fat quality in gilts, but a high-energy level using oilseeds and a low-crude-protein and -amino-acids diet from 80 to 137 kg of body weight could be interesting in IM to maintain or increase fat consistency, respectively. Moreover, in general, immunocastration is effective in avoiding boar taint in males.

Increasing the Dietary Concentration of Lupinus albus L. Decreased Feed Intake and Daily Gain of Immunocastrated Male Pigs

Simple Summary

Boar taint is a major cause of consumer complaints about pork but it can be eliminated by immunizing entire males against gonadotrohpin releasing factor (immunocastrated males). However, immunocastrated males have increased feed intake and backfat compared to entire males, which is an issue in countries such as Australia, where producers are penalized for high backfat. The inclusion of an in-feed ingredient, albus lupins, is one way to suppress the voluntary intake of IC male pigs and subsequently their fat deposition, but the appropriate quantity to include in the diet had not been determined. Albus lupins are thought to reduce feed intake due to slower transit of feed through the digestive system, which then influences satiety. The albus lupin concentration to maximize growth rate, minimize feed intake, maximize carcass weight and minimize backfat depth was 120, 142, 62.7 and 138 g/kg, respectively.

Abstract

An experiment was conducted to determine the appropriate dietary concentration of albus lupins that would lower feed intake and decrease backfat while optimizing the effect on the growth rate of immunocastrated male pigs. The pigs were fed albus lupins (varying from 0 to 200 g/kg) from 2 weeks after the last immunization against GnRF for 14 d prior to slaughter (where d 0 is the day of the last immunization against GnRF). Increasing the dietary albus lupin concentration decreased daily gain for d 15 to 28 (p = 0.004). Daily feed intake also decreased as the concentration of the albus lupins increased for d 15 to 28 (p < 0.001). Carcass weight and backfat decreased as the concentration of dietary albus lupins increased (p = 0.011 and p = 0.024, respectively). The albus lupin concentration to maximize growth rate, minimize feed intake, maximize carcass weight and minimize backfat depth was 120, 142, 62.7 and 138 g/kg, respectively.

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.

Adipose Tissue Gene Expression of Entire Male, Immunocastrated and Surgically Castrated Pigs

Differences in adipose tissue deposition and properties between pig male sex categories, i.e., entire males (EM), immunocastrates (IC) and surgical castrates (SC) are relatively well-characterized, whereas the underlying molecular mechanisms are still not fully understood. To gain knowledge about the genetic regulation of the differences in adipose tissue deposition, two different approaches were used: RNA-sequencing and candidate gene expression by quantitative PCR. A total of 83 differentially expressed genes were identified between EM and IC, 15 between IC and SC and 48 between EM and SC by RNA-sequencing of the subcutaneous adipose tissue. Comparing EM with IC or SC, upregulated genes related to extracellular matrix dynamics and adipogenesis, and downregulated genes involved in the control of lipid and carbohydrate metabolism were detected. Differential gene expression generally indicated high similarity between IC and SC as opposed to EM, except for several heat shock protein genes that were upregulated in EM and IC compared with SC. The candidate gene expression approach showed that genes involved in lipogenesis were downregulated in EM compared with IC pigs, further confirming RNA-sequencing results.

Effect of terminal sire line and timing second vaccination on effectiveness of immunocastration, performance, and carcass and meat quality

Performance (from 10 weeks until slaughter), carcass and meat quality, and effectiveness of immunocastration was compared in crossbred offspring of stress positive (BP+) and negative (BP-) Belgian Piétrain and Canadian Duroc (CD) given the second vaccination of Improvac® at different times (4, 6, 8 weeks before slaughter). CD offspring had a significantly higher daily gain (DG) and feed intake (DFI), and lower predicted lean meat percentage (LMP) and dressing yield compared to BP+ and BP-, while feed conversion ratio (FCR) did not differ. CD offspring had significantly lower drip loss and higher pH_i, intramuscular fat content than BP+ and BP- (except for pH_i). No significant effect of vaccination time on DG nor FCR was observed. Predicted LMP tended to increase as time-post injection decreased, while meat quality was minor affected. Earlier vaccination had no effect on the effectiveness of immunocastration based on testosterone and GnRH-binding.

Influence of Immunocastration on Slaughter Traits and Boar Taint Compounds in Pigs Originating from Three Different Terminal Sire Lines

Simple Summary

Due to the negative public opinion and welfare issues related to surgical castration, gradual introduction of alternatives like entire males and immunocastrates is taking place. Despite several economical and welfare advantages that the alternatives offer, numerous issues (i.e., boar taint, meat quality alterations), as well as their interactions with rearing and breeding (genetic) factors remain unanswered. Therefore, the focus of this study was to investigate the possibility of using different commercial sire lines in three male sex categories (entire males, immunocastrates, surgical castrates) and to compare their carcass traits, meat quality and boar taint compounds. A significant effect of terminal sire line and/or male category together with their interaction was observed for most of the investigated carcass and meat quality traits. The observed interaction should be taken into consideration when deciding on the production of a specific male category.

Abstract

The aim of the research was to investigate the influence of terminal sire line (TSL) and male category (MC) on carcass and meat quality of commercial fatteners. The study was performed on 180 pigs originating from three terminal sire lines: A (Pietrain × Large White), B (pure Pietrain), and C (Pietrain × Duroc × Large White), being assigned to three groups according to MC: immunocastrates (IC, n = 60), surgical castrates (SC, n = 60) and entire males (EM, n = 60). TSL affected most of the carcass and meat quality traits, together with the androstenone concentration. At the same time, MC had a significant effect on fat thickness, ham circumference, drip loss, cooking loss and androstenone and skatole concentrations. A significant interaction effect was observed for carcass length and ham circumference, as well as for most of the measured meat quality traits (except cooking loss, CIE L*, CIE b*, and Warner Bratzler Shear Force (WBSF)). Among the three investigated sire lines, immunocastration was shown to be most beneficial for fatteners sired by the TSL C. However, if deciding to raise EM, fatteners from the TSL B are recommended in terms of carcass and meat quality, although strategies for avoiding boar taint in their carcasses must be taken into consideration.

Effect of Excessive or Restrictive Energy on Growth Performance, Meat Quality, and Intramuscular Fat Deposition in Finishing Ningxiang Pigs

This study investigated the effects of excessive or restrictive energy on growth performance, meat quality, intramuscular fat (IMF) deposition, and related gene expression in finishing Ningxiang pigs. A total of 36 Ningxiang pigs (43.26 ± 3.21 kg) were randomly assigned to three treatments (6 pens of 2 piglets per treatment) and fed by one of three dietary treatments until the pigs of each treatment weighed approximately 75 kg equally. The three treatments were control diet (digestible energy, DE:13.02 MJ/kg, CON), excessive energy diet (DE 15.22 MJ/kg, EE), and restrictive energy diet (DE 10.84 MJ/kg, RE). Results showed that EE improved average daily gain (ADG) and feed conversion ratio (FCR) (p < 0.01), while nothing significantly changed by RE except FCR increasing (p < 0.01). EE increased the content of IMF and triglycerides (TG) (p < 0.05), L*24h and b*45min (p < 0.01), while decreasing cooking loss and meat tenderness in longissimus thoracis (LT) (p < 0.05). b*24h was significantly increased with the increase of energy level (p < 0.01). Meanwhile, EE increased the cross-sectional area (CSA) of muscle fiber and the mRNA expression of myosin heavy chain (MyHC) IIb, acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), and adipocyte fatty-acid binding protein (FABP4) (p < 0.05). In addition, throughout: A diet supplemented with excessive energy promoted IMF deposition by positively changing lipogenic potential while decreasing tenderness by increasing glycolytic muscle fibers, which together affected meat quality. In terms of growth performance and meat quality, the present study suggests that the low-energy diet is suitable for finishing Ningxiang pigs.

The effect of immunocastration on adipose tissue deposition and composition in pigs

Immunocastrated pigs (IC) exhibit intensive fat deposition after immunisation, but the underlying mechanisms of intensified fat metabolism and deposition are not yet fully understood. Moreover, there is also a lack of comparative studies performed on IC, entire males (EM) and surgical castrates (SC). The main objective of our research was, therefore, to characterise the adipose tissue from the quantitative, histo-morphological and biochemical perspectives in IC 5 weeks after their immunisation in comparison to EM and SC. Immunocastrated pigs had an intermediate position in carcass fatness traits between EM (the leanest) and SC (the fattest). The histo-morphological traits of the subcutaneous adipose tissue of IC were similar to those of SC and differed from those of EM; i.e., they exhibited larger adipocytes in the outer backfat and a larger lobulus surface area in both backfat layers than EM. Intensive fat tissue development in IC was corroborated with higher activities of lipogenic enzymes (i.e., fatty acid synthase, malic enzyme, glucose 6-phosphate dehydrogenase, citrate cleavage enzyme), which was especially pronounced in the subcutaneous adipose tissue of IC (1.5- to 2.7-fold higher activity than in EM or SC). The fatty acid composition of the backfat in IC was similar to that in EM pigs. Both IC and EM exhibited less saturated and more polyunsaturated fatty acids than SC. In contrast, the fatty acid composition of the intramuscular fat of longissimus dorsi muscle in IC pigs was more similar to SC than to EM (higher monounsaturated and lower polyunsaturated fatty acid content in IC and SC than EM). In this study, it was demonstrated that immunocastration notably influenced lipid metabolism. This was shown by increased quantity of lipid depots and with changes in adipose tissue cellularity compared to EM, with changes in the fatty acid composition of the intramuscular fat and enhanced lipogenic activity compared to both EM and SC. These results provide new insights into the specificity of adipose tissue development and deposition in IC compared to EM and SC.

The Use of Pork from Entire Male and Immunocastrated Pigs for Meat Products-An Overview with Recommendations

Due to the strong public initiative in Europe and increased regulator focus to mitigate pain, surgical castration of pigs is being gradually abandoned, while the importance of other sex categories like entire males (EM) and immunocastrates (IC) increases. Although beneficial for animal welfare and economics, their use also brings forward several quality problems. Besides the occurrence of boar taint in EM, these include excessive carcass leanness, softer fat, meat color and pH deviations, inferior water holding capacity and increased meat toughness. In this paper, the raw material differences between the male sex categories and their influence on product quality are reviewed, and possible solutions are presented. Using EM for dried or thermally processed products may result in lower processing yields and inferior sensory quality, which may partially be prevented by applying specific processing adaptations. Immunocastration is a viable solution, especially when prolonging the vaccination to slaughter interval. Low to medium levels of boar taint can be effectively managed in most of the meat products, applying procedures like cooking, microbial inoculation or masking (by spices and especially smoking), while highly tainted material can be valorized only by combining various methods and/or with dilution of the tainted meat.

Effect of immunocastration and housing conditions on pig carcass and meat quality traits

The present study investigated the effects of immunocastration and housing conditions on carcass, meat, and fat quality traits. Immunocastrates (IC, n = 48), entire (EM, n = 48), and surgical castrates (SC, n = 48) male pigs were reared under three different housing conditions. The conditions were standard (n = 36), enriched (n = 36, twice as much space as standard and additional outdoor access), or standard with repeated social mixing (n = 72). Pigs of the IC group were vaccinated at the age of 12 and 22 wk. The animals were slaughtered in four batches, balanced for sex category and housing, at the age of 27 wk reaching 124.7 ± 1.0 kg. Immunocastration led to increased fat deposition (i.e., thicker subcutaneous fat at different anatomical locations, more leaf fat, fatter belly in IC than EM, P < 0.05) but did not affect muscularity traits. As a result, EM exhibited higher and SC lower (P < 0.05) carcass leanness than IC. Fatty acids composition of either subcutaneous or intramuscular fat (IMF) agreed with general adiposity, that is, IC were intermediate between EM and SC exhibiting the lowest and highest fat saturation (P < 0.05), respectively. Compared to SC, EM exhibited higher (P < 0.05) levels of muscle oxidation and collagen content than SC, with IC taking an intermediate position in the case of the level of peroxidation and collagen content, or closer to SC as regards to oxidation of muscle proteins (i.e., carbonyl groups). Meat quality (including marbling score, cooking loss, subjective color redness, and chroma) of IC was similar to EM, and both differed (P < 0.05) from SC. However, IC and SC had less (P < 0.05) tough meat than EM, consistent with protein oxidation. The effect of housing was less evident. Mixing of pigs resulted in lower (P < 0.05) carcass weight and fatness in all sex categories with lower (P < 0.05) oleic and higher (P < 0.05) arachidonic acid in IMF of EM.

Performance, carcass and meat quality of pigs submitted to immunocastration and different feeding programs

The feed restriction of pigs aims to improve the nutrient utilization of the diet, reduce carcass fat and increase lean meat. Immunocastration is a painless, reversible technique that improves animal welfare, decreases boar taint in meat, leading to lower fat deposition and increases lean meat. This study aimed at evaluating either feeding (restricted) programs (FP) and castration categories (surgically castrated × immunocastration) in terms of pig performance, carcass traits and meat quality. Castration category and FP did not influence marbling, initial pH and drip loss in loin and ham. However, immunocastrated pigs presented lighter loins and hams with lower ultimate pH, compared to the surgically castrated pigs. The FP with lower feed volume resulted in higher ultimate pH. Immunocastrated males had a higher live weight than those surgically castrated. Also, the more the feed supply decreased, the better the feed conversion. Immunocastrates had lower carcass yields, however these pigs had their backfat thickness decreased and lean meat increased in the carcass, without affecting the loin depth.

Genetic determinism of boar taint and relationship with growth traits, meat quality and lesions

Breeding entire males is an alternative to surgical castration to improve their welfare. However, entire males may have a major quality defect called boar taint. Boar taint is partly due to the presence of androstenone in fat. In this study, we estimated the genetic parameters between androstenone and production traits to evaluate the consequences of selection against boar taint for traits of interest. We focused on growth traits, meat quality, lesions, hormone levels and computerised tomography measurements in purebred Piétrain (P) or Piétrain cross Large White (X) entire males. The number of measured animals varied from 670 P and 734 X for hormones concentrations to 553 P and 645 X for computerised tomography measurements. Skin lesions were measured on live pigs shortly after mixing, at the end of the fattening period, and on carcasses. Heritabilities of traits measured by tomography ranged from low to high: femur density (P: 0.34, X: 0.69), loin eye area (P: 0.53, X: 0.88) and loin eye density (P: 0.12, X: 0.18). The mean number of lesions at each stage was lower in purebred pigs than in crossbreds (entering the fattening stage 4.01 in P and 4.68 in X; before slaughter 3.72 in P and 4.22 in X; on carcass 4.50 in P and 4.96 in X). We also observed a decrease in the average number of lesions between the two stages in live pigs. We found high genetic correlations between stages in purebred pigs (0.74 to 0.76) but low correlations (−0.30 to 0.29) in crossbred pigs. Selection aiming to decrease fat androstenone is feasible (h² = 0.57 in P and h² = 0.71 in X). It would have overall positive effects on meat production and quality traits. Selection aiming to reduce plasma oestradiol would strongly reduce the level of fat androstenone (rg = 0.89 in P and rg = 0.84 in X). Selection against oestradiol is easier and less invasive since it would only require a blood sample rather than a fat biopsy in live animals.

Effect of surgical or immune castration on postprandial nutrient profiles in male pigs

To avoid boar taint before slaughtering, late castration by immunisation against gonadotrophin releasing hormone or immunocastration has been developed. The current study aimed at determining whether differences in feed efficiency between castrated male (CM), immune castrated (IM) and entire male pigs (EM) can be explained by differences in nutrient plasma profiles after a meal. In this study, 24 male pigs (n = 8/type) were enrolled between 14 to 19 weeks of age. Entire and IM pigs ate less and were more feed efficient than CM pigs (p < 0.05). The postprandial plasma profiles of glucose, insulin, urea and amino acids (AA) were determined before (d -6), just after (d 8) and well after (d 16) the decrease in testicular hormones in IM pigs. For each test day, pigs were fasted overnight and subsequently fed a small meal (400 g). On d -6, postprandial profiles of plasma glucose of IM pigs did not differ from the two other types of pigs. On d 8, EM pigs had a greater average plasma glucose concentration than IM and CM pigs (p < 0.05) but the profiles did not differ. On d 16, the differences between profiles of glucose suggest a lower clearance of glucose in EM compared with IM and CM pigs. Plasma insulin did not significantly differ between the three types. Plasma urea profiles did not differ between CM, EM and IC pigs on d -6 whereas CM pigs showed higher plasma urea concentrations than EM and IM thereafter (p < 0.01). Among AA, Lys plasma concentrations were greater in CM than in EM and IM pigs on d -6, d 8 and d 16 (p < 0.05), whereas on d 16 plasma Hypro concentrations were lower in CM than in EM and IM pigs (p < 0.05). The finding that plasma glucose profiles were modified by immunocastration much faster and earlier than urea and AA profiles, suggest that the decrease in testicular hormones impacted energy metabolism more rapidly than protein metabolism.

Sustainability of Pork Production with Immunocastration in Europe

Immunocastration, a technique to replace surgical castration of piglets, consists of two consecutive vaccinations to induce antibodies which transiently suppress testicular functions and avoid boar taint. It is a method to ensure both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively. While all aspects of sustainability have been studied separately, however, a contemporary global overview of different aspects is missing. In immunocastrates, performance results are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After second vaccination, immunocastrates switch from a boar- to a barrow-like status. Therefore, the timing of second vaccination is a fine-tuning tool to balance advantages of boars with environmental and economic benefits against increased risk of welfare problems and boar taint. Nevertheless, both synergic and conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products.

Proteomic Profiles of the Longissimus Muscles of Entire Male and Castrated Pigs as Related to Meat Quality

There are indications of reduced meat quality in entire male pigs (EMs) in comparison to surgically castrated pigs (SCs); however, the differences are not strongly confirmed, and the etiology is not clarified. In the present study, samples of the longissimus dorsi, pars lumborum muscle (LL) from EMs (n = 12) and SCs (n = 12) of the same age and weight were evaluated at the physico-chemical and proteomic level. EMs exhibited lower intramuscular fat content, higher collagen content with higher solubility, a higher level of protein carbonyl groups (indicating higher protein oxidation), lower water holding capacity, and tougher meat than SCs. Proteomic analysis revealed differences in heat shock proteins expression, while a greater abundance of several other identified proteins (malate dehydrogenase, Na/K-transporting adenosintriphosphatase (ATP-ase) subunit alpha-1, and blood plasma proteins) indicates that EMs have a more oxidative metabolic profile than that of SCs. More abundant protein fragments (mainly actin and myosin heavy chain) suggest a higher degree of proteolysis in EMs, which was not followed by lower meat toughness.

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&lt;0.10) to have higher daily gain and lower dressing percentage, higher (P&lt;0.001) pH 45 min and lower (P&lt;0.01) pH 24 h postmortem, affecting (P&lt;0.10) also water holding capacity and objective colour parameters (P&lt;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&lt;0.05) proportion of saturated and higher (P&lt;0.01) proportion of monounsaturated fatty acids accompanied by higher (P&lt;0.001) values of thiobarbituric reactive substances (TBARS). In backfat, ECO pigs showed lower (P&lt;0.05) vitamin E content, higher (P&lt;0.001) TBARS, higher (P&lt;0.01) degree of unsaturation (percentage of polyunsaturated fatty acids), and also higher (P&lt;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.

Supplementing entire male pig diet with hydrolysable tannins: Effect on carcass traits, meat quality and oxidative stability

The purpose of the present study was to investigate the potential impact on carcass and meat quality of a sweet chestnut wood extract (SCWE)diet supplement for pigs, in particular on oxidative stability and fatty acid composition. Entire (non-castrated) male pigs (n=24) were assigned to treatment groups within litter and offered one of 4 finisher diets on an ad libitum basis: T0 (control), T1, T2 or T3, supplemented with 0, 1, 2 or 3% of commercially available SCWE, respectively. The highest SCWE supplementation reduced carcass fat deposition and water holding capacity of meat (higher thawing loss). In fresh meat, SCWE supplementation increased lipid (malondialdehyde) and protein oxidation (carbonyl groups in myofibril isolates). With regard to fat tissue, SCWE supplementation increased the proportion of polyunsaturated fatty acids.

Effect of feed restriction and initial body weight on growth performance, body composition, and hormones in male pigs immunized against gonadotropin-releasing factor

Pigs immunized against gonadotropin-releasing factor (GnRF) have increased carcass fatness compared to entire males; however, the timing of this increase in fatness after the second immunization against GnRF has not been determined. An experiment was conducted to identify and compare the growth performance, body composition, and physiological changes in immunocastrated males (IC males) at different BW and feeding levels. A total of 64 pigs were used in a 2 × 2 × 2 factorial experiment with the treatments being 1) sex (entire males or IC males), 2) initial BW (45.9 kg [light] or 78.3 kg [heavy]), and 3) feeding regime (2.5 times maintenance [restricted] or ad libitum). The pigs were individually housed, and the diets were fed for 4 wk after the second immunization against GnRF until slaughter at either 68.4 kg BW (light) or 105.8 kg BW (heavy). Immunocastrated males on a restricted feed intake had a lower ADG compared to entire males from d 15 to 28 and d 0 to 28 ( 0.011 and 0.011, respectively). Fat deposition was not affected by sex from d 0 to 14, but from d 15 to 28 IC males deposited 45 g/d more fat than entire males ( = 0.025). Immunocastrated male pigs fed ad libitum deposited 87 g/d more fat from d 15 to 28 than entire males fed ad libitum ( = 0.036). However, there was no difference in fat deposition between IC males and entire males when feed intake was restricted from d 15 to 28. Plasma urea nitrogen levels were greater in IC males compared to entire males from d 7 after the second immunization against GnRF ( 0.05 for d 7, 10, 14, 21, and 28). Plasma concentrations of IGF-1 were lower for IC males compared to entire males on d 3, 7, 10, and 28 ( 0.05 for all days). The following conclusions were made: 1) when pigs are immunized at a light BW (50 kg) and/or are on a restricted feed intake, they have a reduced propensity to deposit fat; however, the restriction in feed intake adversely affects growth rate. 2) The majority of fat deposition for males immunized at heavy BW (80 kg) occurs from d 15 to 28 after the second immunization against GnRF.

Effect of time interval between the second Improvest® dose and slaughter and corn dried distillers grains with solubles feeding strategies on carcass composition, primal cutout, and pork quality of immunologically castrated pigs

Effects of dried distillers grains with solubles (DDGS) feeding strategies on carcass composition, primal cutout, and lean quality of immunologically castrated (IC; n=863) pigs were evaluated, and consisted of: 1) corn-soybean meal (CS) diet (PCon); 2) CS+40% DDGS (NCon); 3) CS+40, 30, 20, or 10% DDGS fed in phases 1 to 4, respectively (SD); or 4) CS+40% DDGS fed in phase 1 to 3 and CS in phase 4 (WD). All pigs received the first dose of Improvest® at 11weeks. of age, and the second dose was administered at either 9, 7, or 5weeks. before slaughter at 24weeks. of age. The SD and WD improved carcass dressing percentage and resulted in intermediate primal cut yields and pork loin quality compared with pigs fed PCon and NCon. Increasing the time interval between second dose of Improvest® and slaughter increased adipose tissue accretion but did not affect lean quality of pork.

The Effect of Lupinus albus on Growth Performance, Body Composition and Satiety Hormones of Male Pigs Immunized against Gonadotrophin Releasing Factor

Two hundred and ninety four pigs were used with the aim to develop a dietary management strategy using Lupinus albus L. (albus lupins) to reduce the increase in feed intake and subsequent increase in carcass fatness in pigs immunized against gonadotrophin releasing factor (immunocastrates; IC males) and entire male pigs in the late finishing stage. From day (d) 0 to 28, IC males fed the control diet grew faster (p = 0.009) than entire males fed the control diet but there was no difference in growth rate between sexes for pigs fed albus lupins for 14 days pre-slaughter (Albus 14) or pigs fed albus lupins for 28 days pre-slaughter (Albus 28). From d 15 to 28, IC males receiving the Albus 14 diet grew more slowly (p < 0.001) than entire males receiving the Albus 14 diet. From d 15 to 28 (p < 0.001), IC males fed the control diet ate more feed than entire males fed the control diet, although there was no difference between sexes in feed intake of the Albus 14 and Albus 28 diet. Immunocastrates had a lower backfat when fed either Albus 14 or Albus 28 compared to the control diet, although there was no difference between diets for entire males. There was also a trend for pigs on the Albus 14 and Albus 28 diets to have a higher lean deposition (p = 0.055) and a lower fat deposition (p = 0.056) compared to the pigs on the control diet. Pigs fed the Albus 28 diet had a lower plasma ghrelin concentration compared to pigs fed the Albus 14 or the control diet (p = 0.002). Pigs fed the Albus 28 diet had a higher peptide YY concentration than those fed the control or albus 14 diet (p = 0.004). The inclusion of albus lupins at 20% in the diets of IC male pigs for either 14 or 28 days pre-slaughter was successful in reducing feed intake, body fat and backfat to similar levels of entire males. However, the growth rate of the IC male pigs was impacted more than would be desirable.

Growth performance of immunologically castrated pigs slaughtered at 5, 7, or 9 weeks after the second Improvest dose and fed diets containing corn dried distillers grains with solubles

Growth performance of immunologically castrated (IC) pigs (863 total) was determined at increasing time intervals between the second Improvest (gonadotropin releasing factor analog-diphtheria toxoid conjugate; Zoetis Inc., Florham Park, NJ) dose and slaughter (TD) and with 4 different dried distillers grains with solubles (DDGS) feeding strategies (FS) in a 4 × 3 factorial arrangement of treatments. The feeding period was divided into 4 separate diet phases. Dietary treatments included 1) corn-soybean meal control diets (PCon), 2) a gradual decrease of dietary DDGS inclusion rate from 40%, 30%, 20%, and 10% in phases 1 to 4 (GD), respectively, 3) feeding 40% DDGS diets in phases 1 to 3 and removal of DDGS from the phase 4 diet (WD), and 4) feeding 40% DDGS diets in all 4 phases (NCon). Pigs received the second Improvest dose at 9 (TD9), 7 (TD7), or 5 (TD5) wk before slaughter. In each group, all pigs were slaughtered on the same day. There were no 3-way interactions among FS, TD, and week of feeding period for any measure of growth performance. Pigs fed PCon and WD had greater ( < 0.05) overall ADFI than pigs fed NCon, especially when slaughtered 9 wk after the second Improvest dose (2.45 and 2.44 vs. 2.31 ± 0.08 kg/d, respectively). This response was partly due to withdrawing DDGS from the diet at 19 wk of age (WD), which led to a tendency ( < 0.10) for increased ADFI from the wk 19 to 21 interval to the wk 21 to 24 interval (3.26 vs. 3.51 ± 0.09 kg/d, respectively). During the same time period, ADFI was unchanged ( > 0.05) in pigs fed PCon, GD, and NCon. Overall G:F was improved ( < 0.05) in TD5 pigs compared with TD9 pigs and tended ( < 0.10) to be improved compared with TD7 pigs. Final BW was similar among pigs fed GD, WD, and PCon (123.1, 122.3, and 125.3 kg, respectively), but pigs fed PCon and GD had greater ( < 0.05) BW than pigs fed NCon (120.0 kg). Throughout the growing-finishing period, BW was similar among TD treatments. The GD FS was more effective than the WD FS in maintaining overall G:F (0.424 and 0.414 ± 0.005, respectively) and ADG (0.94 and 0.93 ± 0.03 kg/d, respectively), which were similar ( > 0.05) to those of pigs fed PCon (0.427 ± 0.005 and 0.96 ± 0.03 kg/d, respectively). Growth performance of pigs fed GD more closely reflected that of pigs fed PCon than that of pigs fed WD. Delaying the second dose of Improvest from 9 to 5 wk before slaughter resulted in improved growth performance.

The Effect of Lupinus albus and Calcium Chloride on Growth Performance, Body Composition, Plasma Biochemistry and Meat Quality of Male Pigs Immunized Against Gonadotrophin Releasing Factor

Simple Summary

Pigs immunized against gonadotrophin releasing factor (immunocastrated (IC) males) have an increased feed intake, growth rate, back fat and fat deposition compared to entire males. It is desirable to develop management strategies to limit the increase in feed intake and fat deposition in IC males. This experiment used in-feed ingredients (Lupinus albus (albus lupins) or a combination of calcium chloride and sodium tri-polyphosphate (mineral salts)) to try to suppress the voluntary feed intake of IC male pigs and subsequently fat deposition. Mineral salts decreased feed intake with no effect on fat deposition while albus lupins reduced both feed intake and fat deposition in pigs.

Abstract

Two hundred and ninety-four pigs were used to assess the effect of two ingredients (Lupinus albus (albus lupins) or a combination of calcium chloride and sodium tri-polyphosphate (mineral salts)) on growth performance, body composition and objective meat quality of pigs immunized against gonadotrophin releasing factor (immunocastrates) and entire male pigs in the late finishing phase. Pigs fed mineral salts ate less feed than those fed the control diet with no effect on growth rate (p > 0.05), backfat (p > 0.05) or fat deposition (p > 0.05). Pigs fed albus lupins had a reduced feed intake (p < 0.001 for all time periods), lower growth rate (p < 0.001 for all time periods), lower backfat (p < 0.005) and decreased fat deposition (p < 0.001 for all time periods) compared to those fed the control diet or mineral salts. From day (d) 0–28 pigs fed mineral salts had a better feed conversion ratio (p = 0.001) than those fed albus lupins who in turn had an improved feed conversion compared to the control diet. Immunocastrates had thicker backfat than entire males at the end of the experiment (p < 0.001), however, feeding albus lupins to immunocastrated males reduced backfat thickness to similar to entire males fed the control diet (p = 0.01). With the exception of the increased muscle pH at 45 min post-exsanguination in mineral salts and albus lupins compared with the control diet (p = 0.03) there was no effect of diet on objective pork quality. Pork from IC males had a higher ultimate pH (p < 0.001), was lighter (L*; p = 0.003), more yellow (p = 0.008) and had a higher drip loss (p < 0.001) compared to entire males. Albus lupins show potential in reducing the increase in feed intake and backfat associated with immunocastration. Mineral salts may be useful in situations where a reduction in feed intake and an improvement in feed conversion is desired and reducing fat deposition is not the objective.

Influence of the inflammatory status of entire male pigs on their pubertal development and fat androstenone

Androstenone production increases during pubertal development and plays a major role in boar taint. The objective of the present study was to evaluate the effect of a subclinical inflammation on the pubertal development of boars and hence on fat androstenone. Contrasted hygiene conditions were applied during rearing to increase the variability of the inflammatory status. Boars from a commercial cross line were allocated at 139±0.9 days of age (Day 0) and 81.3±5.9 kg of live weight either to Good (n=61) or Poor (n=54) hygiene conditions until slaughter at 172.9±4.8 days of age and 116.7±4.5 kg live weight. Inflammatory status, growth and pubertal development were evaluated on Day 0, Day 27 and at slaughter by analysing the blood formula, plasma inflammatory proteins; testosterone and oestradiol, salivary cortisol, rectal temperature, live weight, back fat thickness, weight of reproductive organs and clinical scores of organs (lungs, stomach, snout). Fat was collected on Day 27 by biopsy and at slaughter to measure androstenone concentration. A principal component analysis including inflammatory indicators followed by a clustering procedure was performed to identify pigs with a high (Infl+, n=50) or a low (Infl-, n=65) inflammatory status. Infl+ pigs had more granulocytes/ml, higher concentrations of haptoglobin, C-reative protein and cortisol (P<0.05), lower growth rate and higher lung pneumonia score. However, regardless of stage, the inflammatory status had no significant effect on plasma testosterone or oestradiol, fat androstenone or sexual organ development. Present data suggest that a mild inflammatory status has no influence on pubertal development or fat concentration of androstenone in boars.

Genetic relationships between measures of sexual development, boar taint, health, and aggressiveness in pigs

Breeding intact boars is a promising alternative to surgical castration of piglets. Genetic selection should enable farmers to solve problems due to boar taint and aggressiveness while taking into account potential consequences on other traits of interest. The aim of the study was to estimate genetic relations between sexual development, boar taint, health, and aggressiveness. About 1,600 Pietrain (purebred) or Pietrain × Large White (crossbred) boars were raised in a testing station. Blood samples were collected at about 105 kg BW for measuring sex hormones (testosterone and estradiol) and indicators of the inflammatory status (C-reactive protein [CRP], pig major acute-phase protein [pigMAP], and blood formula). Animals were slaughtered 9 d later and measured for boar taint compounds present in fat (androstenone and skatole) and skin lesions on carcass, an indicator of aggressiveness. For both genetic types, heritability was moderate for sex hormones (from 0.17 to 0.29) and skatole (0.24 for purebred and 0.37 for crossbred) and high for androstenone (0.63 and 0.70 for purebred and crossbred, respectively). Genetic correlations between sex hormones and boar taint compounds were moderate to high (from 0.31 to 0.95). Heritability was moderate for CRP (0.24 and 0.46 for purebred and crossbred, respectively) and very low for pigMAP (0.06 and 0.05 for purebred and crossbred, respectively. Numbers of leukocytes had moderate to high heritabilities according to the genetic type (from 0.21 to 0.52). Heritability of skin lesions was moderate for both genetic types (0.31). Genetic correlations were negative between sex hormones and inflammatory measures (from -0.46 to -0.05), positive between testosterone and number of lesions (0.43 and 0.53 for purebred and crossbred, respectively), and low between androstenone and lesions (-0.06 and -0.17 for purebred and crossbred, respectively). Overall, both breeds of pigs had very similar estimations of heritabilities, but estimates of genetic correlations were different for some pairs of traits. It would be possible to select boars based on their plasma concentration of sex hormones to decrease boar taint and aggressiveness without important consequences on the immune response. However, because of the strong links between boar taint and reproductive function, the possible consequences on the reproductive performance should be evaluated.

Effectiveness of an immunocastration vaccine formulation to reduce the gonadal function in female and male mice by Th1/Th2 immune response

Immunocastration has emerged as an alternative to surgical castration in different animal species. This study examined the effectiveness of a new vaccine formulation for immunocastration using the biopolymer chitosan as adjuvant. First, female and male mice (n = 4), in three subsequent experiments were vaccinated at Days 1 and 30 of the study, to determine the immune response profile and gonadal alterations due to immunization. The results demonstrated that the vaccine was able to elicit strong antibody responses against native GnRH hormone (P < 0.01), with a T helper (Th) 1/Th2 immune response profile. Along with this, a suppression of gonadal activity with a decrease of luteal bodies (1.08 ± 0.22 and 4.08 ± 0.39) and antral follicles (1.17 ± 0.32 and 4.5 ± 0.38) in the ovaries of immunized females and control, respectively, and a reduction of seminiferous tubules size (142.3 ± 5.58 mm and 198.0 ± 6.11 mm) and germinal cellular layers (3.58 ± 0.26 and 5.08 ± 0.29) of immunized males and control animals, respectively, were observed (P < 0.01). Then, in a study of long-term immune response due to vaccination in female and male mice (n = 4) from two subsequent experiments, a suppression of gonadal function and an induction of a Th1/Th2 immune response was also observed, determined by both, immunoglobulin and cytokine profiles, which lasted until the end of the study (7 months; P < 0.01). The findings of this study have demonstrated that vaccination with a new immunocastration vaccine inducing a Th1/Th2 immune response against GnRH (P < 0.01) elicit a decrease of gonadal function in male and female mice (P < 0.01). Owing to long-term duration of the antibody levels generated, this vaccine formulation appears as a promising alternative for immunocastration of several animal species where long-lasting reproductive block is needed.

Hydrolysable tannin fed to entire male pigs affects intestinal production, tissue deposition and hepatic clearance of skatole

The effect of adding hydrolysable tannins to the diet of fattening boars was studied. Performance, reproductive organ weights, salivary gland morphology, boar taint compounds and skatole metabolism were evaluated. At 123 days of age and 52 ± 6 kg liveweight, 24 Landrace × Large White boars were assigned within a litter to four treatment groups: control (T0 fed mixture with 13.2 MJ/kg, 17.5% crude proteins) and three experimental diets for which the T0 diet was supplemented with 1%, 2% and 3% of hydrolysable tannin-rich extract (T1, T2 and T3, respectively). Pigs were kept individually with ad libitum access to feed and water and slaughtered at 193 days of age and 122 ± 10 kg liveweight. Adding hydrolysable tannins to the diet had no negative effect on growth performance at 1% and 2%, whereas the 3% inclusion reduced feed intake and resulted in an adaptive response of the salivary glands (particularly parotid gland hypertrophy). Relative to T0, fat tissue skatole concentration was increased in the T1 group, but was similar in T2 and T3. Across treatments tissue skatole concentrations were proportional to the activity of hepatic CYP450. The results indicate the potential of tannin supplementation to reduce boar taint although further investigations are needed in order to establishing optimal dosage.

Field experience with surgical castration with anaesthesia, analgesia, immunocastration and production of entire male pigs: performance, carcass traits and boar taint prevalence

Male piglets are castrated to reduce boar taint and also to reduce aggressive and sexual behaviour. However, the procedure as traditionally performed is painful and negatively affects performance. Large-scale results about the consequences of implementing alternatives on farms are lacking. We, therefore, investigated the practical applicability of the following five alternatives that can be implemented in the short term: surgical castration (1) without pain relief (CONT, control group), (2) with analgesia (MET, Metacam, 0.2 ml, 10 to 15 min before castration), (3) with general anaesthesia (CO2, inhalation, 100% CO2, 25 s, 3 l/min), (4) vaccination against boar taint (IM, two injections with Improvac) and (5) production of entire males (EM). The study consisted of the following two trials: (1) an experimental farm trial with 18 animals/treatment and (2) a large field trial on 20 farms with ~120 male pigs/farm per treatment and all treatments performed on each farm. Performance results as well as data on carcass traits, boar taint (hot-iron method) and testes development and weight were collected in both trials. Neither castration nor administration of analgesia or anaesthesia had an effect on daily gain of the piglets in the farrowing crates (P>0.05). Farmer records indicated that mortality in the farrowing crates (1.1%), nursery pens (1.8%) and fattening stable (2.2%) was not influenced by MET or CO2 compared with EM, IM or CONT (P>0.05). No significant differences were found for daily gain (P>0.05) nor slaughter age (P>0.05). Immunocastrates and EM had a better gain-to-feed ratio (P<0.05) compared with the groups of barrows (CONT, MET and CO2). Lean meat percentage was higher for EM compared with the barrows, and intermediate for IM (P<0.05). Carcass yield was lowest for IM (P<0.05). The hot-iron method indicated that boar taint was eliminated in barrows and IM compared with EM (P<0.001). Average prevalence of strong boar taint was 3% for EM, but varied from 0% to 14% between farms. As the effect of treatment on performance as well as the level of boar taint of EM was farm dependent, farmers should be encouraged to pre-test the different alternatives in order to make a well-considered choice for the best practical and profitable alternative for their farm.