Immunocastration reduces aggressive and sexual behaviour in male pigs

The aim of this study was to evaluate the effectiveness of a gonadotropin-releasing hormone (GnRH) vaccine, Improvac™ (Pfizer Ltd), in suppressing aggressive and sexual behaviour of male pigs. One hundred and thirty-six pigs were assigned to three treatments: entire male pigs (n = 64), immunocastration against GnRH (n = 48) and surgical castration (n = 24). Surgical castration was performed before the age of 1 week. Vaccination comprised two injections: the first injection was given 8 to 11 weeks before slaughter and the second injection 4 weeks before slaughter. After the second injection, immunocastrated pigs showed less non-violent social and aggressive behaviours than entire male pigs of the same age. Mounting was reduced to the same low level as observed in surgically castrated pigs, and more immunocastrated pigs were without skin lesions compared with entire male pigs. Pigs that received the second injection only 1 week before the observation day did not differ significantly in behaviour from those that received the injection 3 weeks before the observation day. Thus, the behaviour seems to change soon after the second injection and these changes remain until slaughter.     

Weight and season affects androstenone and skatole occurrence in entire male pigs in organic pig production

To investigate the extent to which the level of androstenone and skatole decreases with a decrease in live weight and/or age at slaughter of entire male pigs produced under organic standards, 1174 entire male pigs were raised in parallel in five organic herds, distributed across four batches in summer and winter. The median androstenone level was high for organic entire male pigs (1.9 µg/g), but varied greatly both within and between herds. Median skatole level was 0.05 µg/g, also with a wide range both within and between herds. Decreasing live weight over the range of 110±15.6 kg s.d. was found to decrease androstenone as well as skatole concentration, however, with different patterns of association. Age did not have significant direct effect on either androstenone or skatole levels. Androstenone levels were higher during winter than summer (P<0.0001), but no difference in skatole was found between seasons. The study concludes that decreasing live weight at slaughter could be an applicable management tool to reduce risk of boar taint and the level of tainted carcasses for a future production of entire male pigs within the organic pig production system, although further studies are needed as great variation in boar taint was found also for low weight animals.     

Stunning pigs with nitrogen and carbon dioxide mixtures: effects on animal welfare and meat quality

The aim of this study was to assess the effect of exposure to the gas mixtures of 70% nitrogen (N₂) and 30% carbon dioxide (CO₂; 70N30C), 80% N₂ and 20% CO₂ (80N20C) and 85% N₂ and 15% CO₂ (85N15C) on aversion, stunning effectiveness and carcass, as well as meat quality in pigs, and to compare them with the commercial stunning of 90% CO₂ (90C). A total of 68 female pigs were divided into four groups and stunned with one of the gas mixtures. During the exposure to the gas, behavioural variables (retreat attempts, escape attempts, gasping, loss of balance, muscular excitation and vocalizations) were recorded, and at the end of the stunning, corneal reflex and rhythmic breathing were assessed. After slaughter, meat quality parameters such as pH at 45 min post mortem (pH45) and at 24 h post mortem (pHu), electrical conductivity, drip loss and colour, in the Longissimus thoracis (LT) and Semimembranosus (SM) muscles were measured, and the presence of ecchymosis on the hams was noted. The PROC MIXED and the PROC GENMOD of SAS® were used to analyse the parametric and binomial variables, respectively. The ‘gas mixture’ was always considered a fixed effect and the ‘live weight’ as a covariate. To assess the correlation between meat quality and behaviour measures, PROC CORR was used. Pigs exposed to 90C showed a higher percentage of escape attempts and gasping, a lower percentage of vocalization and shorter muscular excitation phase than pigs exposed to the other N₂ and CO₂ mixtures (P < 0.05). After stunning, no pig exposed to 90C showed corneal reflex or rhythmic breathing, whereas 85% and 92% of the animals exposed to N₂ and CO₂ mixtures showed corneal reflex and rhythmic breathing, respectively. Animals stunned with 80N20C and 85N15C had a lower pH45 (P < 0.01) than animals exposed to 90C. Electrical conductivity in the SM muscle was lower (P < 0.001) in 90C and 70N30C pigs than in 80N20C and 85N15C pigs, whereas in LT, it was lower (P < 0.05) in 90C pigs than in 85N15C. As the CO₂ concentration of the gas mixture was decreased, the prevalence of exudative pork increased. Twenty-five percent of animals exposed to N₂ and CO₂ mixtures (n = 68) had ecchymosis in their carcasses, whereas no animal stunned with 90C had ecchymosis. In conclusion, although N₂ and CO₂ stunning exhibit fewer signs of aversion than 90C, their induction time to unconsciousness is longer, and this may negatively affect meat and carcass quality.     

Influence of breed and slaughter weight on boar taint prevalence in entire male pigs

Piétrain (P), Large White (LW) and Belgian Landrace stress negative (BN) boars were slaughtered at 50, 70, 90 or 110 kg live weight to investigate breed differences and the effect of slaughter weight on boar taint prevalence. Boar taint was quantified by four different methodologies: sensory evaluation of neckfat heated with a hot iron in the slaughterhouse, sensory evaluation of meat by consumer panels, sensory evaluation of fat and meat by expert panels and laboratory analysis of indole, skatole and androstenone in backfat. Skatole levels in backfat were significantly higher for LW and BN than for P boars. The androstenone levels and the hot iron method revealed a significant interaction between breed and slaughter weight. On the other hand, experts detected an effect of weight on the androstenone odour perception, which was significantly higher in fat from boars slaughtered at 90 kg compared with 50 kg, and significantly higher in meat from boars slaughtered at 110 kg compared with 50 kg. Consumers did not detect differences in the sensory characteristics among breeds or slaughter weight. These results indicate opportunities to minimise the risk of boar taint in entire male pigs by carefully selecting a combination of breed and slaughter weight. Along with the optimal slaughter weight, the effectiveness of reducing boar taint by lowering slaughter weight appeared to be breed dependent.     

Influence of social mixing and group size on skin lesions and mounting in organic entire male pigs

Alternatives to surgical castration are needed, due to stress and pain caused by castration of male pigs. One alternative is production of entire male pigs. However, changed behaviour of entire males compared with castrated males might adversely affect the welfare of entire males and changes in management procedures and production system might be needed. Elements from the organic pig production system might be beneficial in this aspect. The aim of this article is to investigate the effect of grouping strategy including social mixing and group size on levels of mounting behaviour and skin lesions, hypothesising that procedures that disrupt the social stability (e.g. regrouping) will have a larger negative effect in small groups compared with large groups. Approximately 1600 organic entire male pigs of the breed (Landrace×Yorkshire)×Duroc were reared in parallel in five organic herds, distributed across four batches in a 2×2 factorial design in order to test the influence of social mixing (presence or absence of social mixing at relocation) and group size (15 and 30 animals). Animals were able to socialise with piglets from other litters during the lactation period, and were all mixed across litters at weaning. A second mixing occurred at insertion to fattening pens for pigs being regrouped. Counting of skin lesions (1348 or 1124 pigs) and registration of mounting behaviour (1434 or 1258 pigs) were done on two occasions during the experimental period. No interactive effects were found between social mixing and group size on either skin lesions or mounting frequency. Herd differences were found for both mounting frequency and number of skin lesions. No association between skin lesions and mounting were revealed. Social mixing and group size were shown as interacting effects with herds on mounting frequency (P<0.0001), but with no consistent pattern across all herds. In addition, no effect of social mixing was found on mean number of skin lesions, but more lesions were observed in large groups (P<0.036). This could indicate that keeping entire male pigs in groups of 30 animals as compared with smaller groups of 15 may marginally decrease the welfare of these animals.     

YNS益肤面霜对豚鼠皮肤变态反应及肠道菌群的影响

建立豚鼠皮肤变态反应模型,并使用YNS益肤面霜对皮肤变态反应模型进行干预,探讨这种面霜对改善及修复受损皮肤的作用及其对豚鼠肠道菌群的影响。

豚鼠24只,随机分成4组：对照组、阳性组、化妆品组和治疗组,每组6只。致敏接触后进行激发反应。提取4组豚鼠粪便标本DNA,使用16S rRNA高通量测序检测肠道菌群构成。

治疗组豚鼠皮肤致敏率为16.7%。益肤面霜治疗对肠道菌群alpha多样性影响不大,但有降低厚壁菌门（Firmicutes）与拟杆菌门（Bacteroidetes）比值（F/B）及粪球菌属（Coprococcus）相对丰度的趋势,有利于皮肤变态反应豚鼠肠道菌群组成的恢复。

YNS益肤面霜对皮肤具有改善及修复作用,并对豚鼠肠道菌群具有一定影响。

     

微等离子束对豚鼠皮肤超微结构分析和羟脯氨酸测定

目的观察微等离子束对豚鼠皮肤胶原组织作用效应的组织学和超微结构变化及羟脯氨酸含量测定,探讨微等离子束的作用机理。方法选择15只豚鼠,每只豚鼠背部划分为实验侧和空白对照侧2个等分区域,给予60W/10 kJ微等离子束照射,于作用后即刻、1周后和1月后分别切取实验侧及空白对照部位皮肤行组织病理维多利亚-立春红染色,透射电镜分析和羟脯氨酸检测试剂盒进行含量测定。结果 60 W/10 kJ即刻表现为表皮局灶性出现点阵状改变,部分表皮出现汽化缺失或者坏死变性,真皮浅层胶原组织出现点阵化表现和明显均质化;特殊染色显示微等离子束主要影响真皮胶原纤维,形成局灶性胶原纤维凝集和变性。1周后皮肤浅层胶原组织结构逐渐致密,排列有序,有少量组织细胞。1月后皮肤浅层胶原组织明显增厚,胶原纤维增粗并排列致密,弹力纤维呈局灶性增粗。透射电镜显示微等离子束作用后表皮细胞较完整,细胞间结构正常,但真皮胶原丧失正常结构,细胞结构消失,大量细胞凋亡明显,1月后仍可见少量细胞凋亡的表现但胶原结构逐渐恢复,浅层胶原纤维排列明显致密。羟脯氨酸测定显示微等离子束作用1周后羟脯氨酸含量要高于作用之前,但是差异性不具有统计学意义（P〉0.05）;1月后羟脯氨酸含量要明显高于作用前,差异性具有统计学意义（P〈0.05）。结论微等离子束对豚鼠皮肤胶原组织作用有明显的刺激效应,其主要靶组织为真皮胶原组织,可以明显促进皮肤新生胶原的增生。     

Biochemical, nutritional and genetic effects on boar taint in entire male pigs

Pork odour is to a great extent affected by the presence of malodorous compounds, mainly androstenone and skatole. The present review outlines the current state of knowledge about factors involved in the regulation of androstenone and skatole in entire male pigs. Androstenone is a pheromonal steroid synthesised in the testes and metabolised in the liver. Part of androstenone accumulates in adipose tissue causing a urine-like odour. Skatole is produced in the large intestine by bacterial degradation of tryptophan and metabolised by hepatic cytochrome P450 enzymes and sulphotransferase. The un-metabolised part accumulates in adipose tissue, causing faecal-like odour. Androstenone levels are mostly determined by genetic factors and stage of puberty, whereas skatole levels in addition to genetic background and hormonal status of the pigs are also controlled by nutritional and environmental factors. To reduce the risk of tainted carcasses entering the market, male pigs are surgically castrated in many countries. However, entire males compared to castrates have superior production characteristics: higher growth rate, better feed efficiency and leaner carcasses. Additionally, animal welfare aspects are currently of particular importance in light of increasing consumers' concerns. Nutrition, hormonal status, genetic influence on boar taint compounds and the methods to develop genetic markers are discussed. Boar taint due to high levels of skatole and androstenone is moderately heritable and not all market weight entire males have boar taint; it should thus be possible to select for pigs that do not have boar taint. In these studies, it is critical to assess the steroidogenic potential of the pigs in order to separate late-maturing pigs from those with a low genetic potential for boar taint. A number of candidate genes for boar taint have been identified and work is continuing to develop genetic markers for low boar taint. More research is needed to clarify the factors involved in the development of boar taint and to develop additional methods to prevent the accumulation of high concentrations of skatole and androstenone in fat. This review proposes those areas requiring further research.     

Effect of hydrolysable tannins on intestinal morphology,proliferation and apoptosis in entire male pigs

This study aimed to evaluate the effect of hydrolysable tannin supplementation on morphology, cell proliferation and apoptosis in the intestine and liver of fattening boars. A total of 24 boars (Landrace × Large white) were assigned to four treatment groups: Control (fed commercial feed mixture) and three experimental groups fed the same diet supplemented with 1%, 2% and 3% of hydrolysable tannin-rich extract. Animals were housed individually with ad libitum access to feed and then slaughtered at 193 d of age and 122 ± 10 kg body weight. Diets supplemented with hydrolysable tannin affected the morphometric traits of the duodenum mucosa as reflected in increased villus height, villus perimeter and mucosal thickness. No effect was observed on other parts of the small intestine. In the large intestine, tannin supplementation reduced mitosis (in the caecum and descending colon) and apoptosis (in the caecum, ascending and descending colon). No detrimental effect of tannin supplementation on liver tissue was observed. The present findings suggest that supplementing boars with hydrolysable tannins at concentrations tested in this experiment has no unfavourable effects on intestinal morphology. On the contrary, it may alter cell debris production in the large intestine and thus reduce intestinal skatole production.     

Effects of deoxynivalenol and sodium meta-bisulphite on nutrient digestibility in growing pigs

ABSTRACT

Deoxynivalenol (DON), a mycotoxin synthesised by the Fusarium, is known to affect the growth of pigs. This effect can be attenuated with sodium meta-bisulphite (SBS). The aim of this study was to evaluate the effect of SBS with antioxidant blend on nutrient digestibility in pigs fed a diet contaminated naturally with DON. Six crossbred castrated pigs fitted surgically with single-T cannulas in the distal ileum received one of four barley-corn-soybean diets with or without SBS. After 8 d of feeding, faeces and ileal digesta were collected for 2 d. Apparent ileal digestibility (AID) of the dry matter (DM), energy, nutrients and DON, and apparent total tract digestibility (ATTD) of DM, acid detergent fibre (ADF), neutral detergent fibre (NDF), energy and DON were evaluated. The AID of phosphorus, calcium and some amino acids was increased (p < 0.05) in the DON diets whereas the ATTD of DM and energy tended to decrease (p = 0.064 and p = 0.071). SBS reduced the AID of DM, energy, ADF, ether extract, phosphorus and DON (p < 0.05) but had no effect on the ATTD of DM, energy, fibre or DON. These results show that DON improved the AID of some nutrients but tended to reduce the ATTD of energy, which could explain, although anorexia is the main effect of DON on live weight gain, the reported negative effect of DON on pig growth. Finally, SBS with antioxidant blend had reduced AID of some nutrients and intestinal absorption of DON.     

Effects of cubicle characteristics on animal welfare indicators in dairy cattle

Cubicle characteristics such as cubicle dimensions or management factors such as cow-to-cubicle ratio could affect health and behaviour of dairy cows. The objective of this study was to estimate effects of cubicle characteristics on animal welfare indicators in dairy cattle. A total of 64 loose housing farms in Germany were assessed once during the winter housing period by one experienced assessor. Nearly 15% of the dairy cows had access to pasture during summer months for <6 h/day, whereas 85% were zero-grazing farms. Selected animal welfare indicators (duration of the lying down process, collisions of cows with cubicles, cows lying outside cubicles, cow cleanliness, integument alterations, lameness and subclinical mastitis incidence) of the Welfare Quality® protocol and cubicle characteristics such as cow-to-cubicle ratio and cubicle dimensions were recorded. Data were statistically analysed using a multiple linear regression approach. Pasture access and cubicle type were considered as potential influencing factors. Wider cubicles positively affected the proportion of dairy cows with dirty flanks (−18.5% per 10 cm increase) but increased the number of cows with severe integument alterations (+8.9% per 10 cm increase). Larger lying areas reduced the percentage of cows with dirty udders (−2.9% per 10 cm² increase). Longer distances from neck rail to curb were associated with higher prevalence of cows with dirty flanks (+3.1% per 10 cm increase) and subclinical mastitis incidence (+1.2% per 10 cm increase). With increasing neck rail height, the duration of the lying down process (−0.1 s per 10% increase), the percentages of cows with dirty legs (−8.4% per 10 cm increase), dirty udders (−7.0% per 10 cm increase) and severe lameness (−3.0% per 10 cm increase) decreased. Compared with rubber mat-equipped cubicles, deep-bedded cubicles showed a reduction in the lying down duration (−0.8 s), percentages of cows with dirty legs (−34.2%), dirty udders (−30.5%) and lesions and swellings (−13.1%). Compared with farms that did not provide any summer grazing, pasture access was associated with an increase of cows with severe lameness (+5.6%). Contrastingly, the number of cows with subclinical mastitis incidence was lower when cows had access to pasture in summer (−5.4%). Findings of the present study indicate several associations between cubicle characteristics and animal welfare in dairy cattle. Bedding type was found as the most influencing factor in terms of health and behaviour. Results of this study are valuable for farmers to identify the optimal cubicle design and improve the animal welfare level.     

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.     

Effects of supplemental zinc amino acid complex on gut integrity in heat-stressed growing pigs

Heat stress (HS) jeopardizes livestock health and productivity and both may in part be mediated by reduced intestinal integrity. Dietary zinc improves a variety of bowel diseases, which are characterized by increased intestinal permeability. Study objectives were to evaluate the effects of supplemental zinc amino acid complex (ZnAA) on intestinal integrity in heat-stressed growing pigs. Crossbred gilts (43±6 kg BW) were ad libitum fed one of three diets: (1) control (ZnC; 120 ppm Zn as ZnSO₄; n=13), (2) control+100 ppm Zn as ZnAA (Zn220; containing a total of 220 ppm Zn; n=14), and (3) control+200 ppm Zn as ZnAA (Zn320; containing a total of 320 ppm Zn; n=16). After 25 days on their respective diets, all pigs were exposed to constant HS conditions (36°C, ∼50% humidity) for either 1 or 7 days. At the end of the environmental exposure, pigs were euthanized and blood and intestinal tissues were harvested immediately after sacrifice. As expected, HS increased rectal temperature (P⩽0.01; 40.23°C v. 38.93°C) and respiratory rate (P⩽0.01; 113 v. 36 bpm). Pigs receiving ZnAA tended to have increased rectal temperature (P=0.07; +0.27°C) compared with ZnC-fed pigs. HS markedly reduced feed intake (FI; P⩽0.01; 59%) and caused BW loss (2.10 kg), but neither variable was affected by dietary treatment. Fresh intestinal segments were assessed ex vivo for intestinal integrity. As HS progressed from days 1 to 7, both ileal and colonic transepithelial electrical resistance (TER) decreased (P⩽0.05; 34% and 22%, respectively). This was mirrored by an increase in ileal and colonic permeability to the macromolecule dextran (P⩽0.01; 13- and 56-fold, respectively), and increased colonic lipopolysaccharide permeability (P⩽0.05; threefold) with time. There was a quadratic response (P⩽0.05) to increasing ZnAA on ileal TER, as it was improved (P⩽0.05; 56%) in Zn220-fed pigs compared with ZnC. This study demonstrates that HS progressively compromises the intestinal barrier and supplementing ZnAA at the appropriate dose can improve aspects of small intestinal integrity during severe HS.     

Effects of fermentation products of Ganoderma lucidum on growth performance and immunocompetence in weanling pigs

The purpose of this study was to test fermentation, for its products of a Chinese medicinal mushroom, Ganoderma lucidum, cultured by submerged fermentation for its effect on growth performance and immunocompetence in weanling piglets. In Experiment 1, 72 weanling piglets were allotted to one of four treatments receiving these fermentation products (GLF, expressed as amount of β-glucans) at 0 (control), 50, 100, and 150 mg/kg feed for 4 weeks. The results showed that at a supplementation level of 50 mg/kg feed, GLF caused the best growth performance, the highest pseudorabies antibody titre, and a decrease of blood glucose level. It was also demonstrated that GLF up-regulated the cell-mediated immune response related cytokines (IL-2, IFN-γ, and TNF-α) expression in different lymphoid tissues. After challenging with porcine circovirus (PCV) type 2 (Experiment 2), a supplementation with 50 mg GLF per kg feed also inhibited PCV-2 virus amplification, and ameliorated lymphocyte depletion in different lymphoid tissues. Conclusively, feed supplemented with GLF at 50 mg/kg could be beneficial to counteract the physiological stress in weanling piglets.     

Effects of repeated aggressive encounters on approach to a female and plasma testosterone in male mice

Effects of repeated experience of aggression accompanied by social victories or social defeat in 10 daily agonistic confrontations on testosterone levels in and the behavioral response of CBA/Lac male mice exposed to a receptive female from behind a perforated transparent partition have been examined. Testosterone levels were not changed significantly in the mice that had consistently been victorious over 10 days (winners) or in the mice that had consistently been defeated over 10 days (losers). Losers and controls (mice that had been caged individually for 5 days) responded with increased levels of behavioral activity near the partition and elevated testosterone. Winners showed a significantly poorer behavioral and hormonal response. It is concluded that the repeated display of aggression by male mice led to a reduction in both their behavioral and neuroendocrine responses to an estrous female.     

Effects of weight, temperature and behaviour on the circadian rhythm of salivary cortisol in growing pigs

In farm animals, salivary cortisol has become a widely used parameter for measuring stress responses. However, only few studies have dealt with basal levels of concentration of cortisol in pigs and its circadian rhythm. The aim of this study was to examine the effects of ambient temperature and thermoregulatory behaviour on the circadian rhythm of salivary cortisol levels in fattening pigs. Subjects were 30 fattening pigs of different weight (60 to 100 kg), kept in six groups in an uninsulated building in pens with partly slatted floors. Saliva samples were taken every 2 h over periods of 24 h at different ambient temperatures at two times in winter and four times in summer. Thermoregulatory behaviour was recorded in the same 24-h time periods. The effect of time of day, body weight, ambient temperature and behaviour on the cortisol level was analysed using a mixed-effects model. Two peaks of cortisol levels per day were found. This circadian pattern became more pronounced with increasing weight and on days where thermoregulatory behaviour was shown. Mean cortisol levels per day were affected by weight but not by thermoregulatory behaviour. From our data, we conclude that long-term variations in cortisol concentration may be influenced by increasing age and weight more than by the respective experimental situation. In assessing animal welfare, it seems more reliable to consider the circadian pattern of cortisol concentration instead of only one value per day.     

Age‐dependent male mating tactics in a spider mite—A life‐history perspective

Males often fight with rival males for access to females. However, some males display nonfighting tactics such as sneaking, satellite behavior, or female mimicking. When these mating tactics comprise a conditional strategy, they are often thought to be explained by resource holding potential (RHP), that is, nonfighting tactics are displayed by less competitive males who are more likely to lose a fight. The alternative mating tactics, however, can also be explained by life‐history theory, which predicts that young males avoid fighting, regardless of their RHP, if it pays off to wait for future reproduction. Here, we test whether the sneaking tactic displayed by young males of the two‐spotted spider mite can be explained by life‐history theory. We tested whether young sneaker males survive longer than young fighter males after a bout of mild or strong competition with old fighter males. We also investigated whether old males have a more protective outer skin—a possible proxy for RHP—by measuring cuticle hardness and elasticity using nanoindentation. We found that young sneaker males survived longer than young fighter males after mild male competition. This difference was not found after strong male competition, which suggests that induction of sneaking tactic is affected by male density. Hardness and elasticity of the skin did not vary with male age. Given that earlier work could also not detect morphometric differences between fighter and sneaker males, we conclude that there is no apparent increase in RHP with age in the mite and age‐dependent male mating tactics in the mite can be explained only by life‐history theory. Because it is likely that fighting incurs a survival cost, age‐dependent alternative mating tactics may be explained by life‐history theory in many species when reproduction of old males is a significant factor in fitness.     

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.     

Effects of dietary fat on the saturated and monounsaturated fatty acid metabolism in growing pigs

The effect of dietary fats differing in fatty acid (FA) composition on the metabolism of saturated FA (SFA) and monounsaturated FA (MUFA) in growing pigs was investigated. The deposition of FA in the body and the fate of individual dietary FA were assessed after slaughter. Gilts with an initial body weight (BW) of 60 kg were used as experimental animals. Six pigs were slaughtered at 60 kg BW, while further 18 pigs received three isoenergetic and isonitrogen experimental diets containing linseed oil, rapeseed oil or beef tallow at 50 g/kg diet until they reached 105 kg (six pigs per group). The chemical composition and the content of FA in the whole body were determined and compared across groups. Regardless of dietary treatment, the whole body contained similar amounts of protein, fat and total FA. The total accumulation (percentage of net intake and de novo production) of SFA and MUFA was similar in all groups, but the processes of elongation and desaturation of SFA and MUFA depended upon the type of FA added to the diet. A high dietary content and intake of MUFA inhibits desaturation compared to SFA- and PUFA-rich diets, whereas a high SFA content and intake lowers elongation rate. The increasing net intake of total SFA and MUFA was associated with a lower total de novo production of these FA in the whole body of pigs.