Early vaccination with Improvac®: effects on performance and behaviour of male pigs

The aim of this study was to investigate the effect of giving a two-dose regimen of gonadotropin-releasing hormone vaccine, Improvac® (Pfizer Ltd), earlier than currently recommended, on performance and behaviour of growing/finishing pigs. Cross-bred male pigs (n = 192) were randomly allocated, within a litter, into four groups at birth: one group of pigs surgically castrated without anaesthesia before one week of age, a second group of early vaccinated pigs given Improvac at 10 and 14 weeks of age, a third group of standard vaccinated pigs given Improvac at 16 and 20 weeks of age, so that the second vaccination was given 4 to 6 weeks before slaughter as recommended by the manufacturer, and a fourth group of entire male pigs. The experiment started when the pigs were 12 weeks old and lasted until 25 weeks of age, when the pigs were slaughtered. The pigs were fed restrictedly. Daily weight gain and feed conversion during the entire raising period did not differ significantly between groups. Estimated lean meat content of early vaccinated and surgically castrated pigs was lower when compared with entire male pigs, whereas standard vaccinated pigs did not differ from entire males. Dressing percentage was higher in early vaccinated and surgically castrated pigs than in standard vaccinated and entire male pigs, partly because of lower size and weight of reproductive organs. For both groups of vaccinated pigs, both problematic and non-problematic behaviours decreased after their second injection, from the levels of entire males to those of surgically castrated pigs. After the second injection, pigs of both vaccination groups performed no mountings, in contrast with entire male pigs of the same age. Skin lesions at slaughter were fewer and less severe for vaccinated pigs compared with entire male pigs. No difference in income per carcass was observed for surgically castrated or vaccinated pigs. However, for entire male pigs the income was lower, as the payment system in Sweden also takes into consideration the additional cost for boar taint analyses and reduced payment for tainted carcasses. Under our experimental conditions, early vaccination with Improvac can be used as an alternative to the recommended schedule to minimise problematic behaviour with unaffected profitability.     

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.     

Effects of dietary enrichment with a marine oil-based n-3 LCPUFA supplement in sows with predicted birth weight phenotypes on growth performance and carcass quality of offspring

Effects of a marine oil-based n-3 LCPUFA supplement (mLCPUFA) fed from weaning until the end of the next lactation to sows with a predicted low litter birth weight (LBW) phenotype on growth performance and carcass quality of litters born to these sows were studied, based on the hypothesis that LBW litters would benefit most from mLCPUFA supplementation. Sows were allocated to be fed either standard corn/soybean meal-based gestation and lactation diets (CON), or the same diets enriched with 0.5% of the mLCPUFA supplement at the expense of corn. The growth performance from birth until slaughter of the litters with the lowest average birth weight in each treatment (n=24 per treatment) is reported in this paper. At weaning, each litter was split between two nursery pens with three to six pigs per pen. At the end of the 5-week nursery period, two barrows and two gilts from each litter that had individual birth weights closest to their litter average birth weight, were moved to experimental grow–finish pens (barn A), where they were housed as two pigs per pen, sorted by sex within litter. Remaining pigs in each litter were moved to another grow–finish barn (barn B) and kept in mixed-sex pens of up to 10 littermates. After 8 weeks, one of the two pigs in each pen in barn A was relocated to the pens holding their respective littermates in barn B. The remaining barrows and gilts were individually housed in the pens in barn A until slaughter. Maternal mLCPUFA supplementation increased docosahexaenoic acid (DHA) concentration in the brain, liver and Semitendinosus muscle of stillborn pigs (P<0.01), did not affect eicosapentaenoic acid and DHA concentrations in sow serum at the end of lactation, and did not affect average daily gain, average daily feed intake or feed utilization efficiency of the offspring. BW was higher (P<0.01) in the second half of the grow–finish phase in pigs from mLCPUFA sows compared with controls in barn A, where space and competition for feed was minimal, but not barn B. Carcass quality was not affected by treatment for pigs from barn A, but maternal mLCPUFA supplementation negatively affected carcass quality in pigs from barn B. Collectively, these results suggest that nutritional supplementation of sows can have lasting effects on litter development, but that feeding mLCPUFA to sows during gestation and lactation was not effective in improving growth rates or carcass quality of LBW litters.     

Consumer evaluation of meat quality from barrows,immunocastrates and boars in six countries

The practice of surgical castration of piglets and its alternatives is still under debate. Production of boars may impair meat quality due to boar taint and reduced tenderness compared to meat from surgically castrated male pigs, while immunocastration reduces boar taint and may improve meat quality but seems to be less accepted by the pig chain. In this study, we aimed to evaluate the consumer’s sensory appreciation of meat from barrows (BAs), immunocastrates (ICs) and boars (BOs) in six European countries, taking into account the selection of tainted carcass and consumers’ appreciation of boar taint. Loin chops of 30 BAs, 30 ICs and 30 BOs were evaluated by 752 consumers in six countries: Belgium, Czech Republic, Poland, Portugal, Romania and Spain. Consumers rated odour, flavour, tenderness, juiciness, overall liking and willingness to buy and sensitivity to and liking of androstenone (AND) and liking of skatole (SKA) was also tested. In each of the six countries, consumers liked the odour of the BO samples less than that of BA, and IC intermediate. For flavour, tenderness, juiciness, overall liking and willingness to buy, liking scores given by the Czech, Polish and Portuguese consumers significantly differed between the BA, BO and IC. Willingness to buy was highest for BA by Czech and Polish consumers and for BA and IC by Portuguese consumers. The frequency of the negative check all terms that apply terms also differed, with a higher frequency of disgusting for BO compared to BA and IC and of off-flavour, irritating, manure, sweat, disappointing compared to BA, and intermediate for IC. 31% of the consumers disliked the odour of AND (NEG_AND), and 36% of them were not sensitive; in contrast, 77% of the consumers disliked SKA (NEG_SKA). The decrease in flavour liking score for BO compared to BA and IC was more outspoken by the NEG_AND consumer, while NEG_SKA consumers gave an overall lower liking score independent of the type of male pig. The results of this study indicate that IC can be a valid alternative for surgical castration.     

Growth performance, carcass characteristics and bioavailability of isoflavones in pigs fed soy bean based diets

A growth trial with 38 weaners (castrated male pigs) was designed to compare the growth performance and carcass quality of pigs fed diets containing either soy bean meal or soy protein concentrate in a pair-feeding design. Soy bean meal (SBM) and soy protein concentrate (SPC) differed in isoflavone (daidzein plus genistein) content (782 microg/g in SBM and 125 microg/g in SPC, respectively). During the experiment, all pigs were fed four-phases-diets characterized by decreasing protein concentrations with increasing age (weaner I, weaner II, grower, finisher diets). Rations of control and experimental groups were isoenergetic, isonitrogenous, and isoaminogen. The weanling pigs with an initial live weight of 8.4 +/- 1.1 kg were allotted to flat deck boxes. During the growing/finishing period (days 70-170 of age), the pigs were housed in single boxes. Both, the weaning and the grower/finishing performances (daily body weight gain, feed intake, feed conversion ratio) were similar in both groups. No differences were found between the groups in carcass composition (percentages of cuts, tissues, and protein/fat), and meat quality of pigs. Moreover, the IGF-1R mRNA expression in longissimus muscle was not influenced by the kind of soy product. However, circulating levels of isoflavones were clearly different between pigs fed SBM (genistein 239 +/- 44; daidzein 162 +/- 42; equol 12 +/- 4 ng/ml plasma) and animals fed SPC (genistein 22 +/- 9 and daidzein 8 +/- 3, and equol 10 +/- 3 ng/ml plasma). The results confirm the expected differences in the bioavailability of soy isoflavones, yet, there were no significant differences in performance of pigs fed either soy bean meal or soy protein concentrate.     

Growth performance,carcass characteristics and bioavailability of isoflavones in pigs fed soy bean based diets

A growth trial with 38 weaners (castrated male pigs) was designed to compare the growth performance and carcass quality of pigs fed diets containing either soy bean meal or soy protein concentrate in a pair-feeding design. Soy bean meal (SBM) and soy protein concentrate (SPC) differed in isoflavone (daidzein plus genistein) content (782?μg/g in SBM and 125?μg/g in SPC, respectively). During the experiment, all pigs were fed four-phases-diets characterized by decreasing protein concentrations with increasing age (weaner I, weaner II, grower, finisher diets). Rations of control and experimental groups were isoenergetic, isonitrogenous, and isoaminogen. The weanling pigs with an initial live weight of 8.4?±?1.1?kg were allotted to flat deck boxes. During the growing/finishing period (days 70?–?170 of age), the pigs were housed in single boxes. Both, the weaning and the grower/finishing performances (daily body weight gain, feed intake, feed conversion ratio) were similar in both groups. No differences were found between the groups in carcass composition (percentages of cuts, tissues, and protein/fat), and meat quality of pigs. Moreover, the IGF-1R mRNA expression in longissimus muscle was not influenced by the kind of soy product. However, circulating levels of isoflavones were clearly different between pigs fed SBM (genistein 239?±?44; daidzein 162?±?42; equol 12?±?4?ng/ml plasma) and animals fed SPC (genistein 22?±?9 and daidzein 8?±?3, and equol 10?±?3?ng/ml plasma). The results confirm the expected differences in the bioavailability of soy isoflavones, yet, there were no significant differences in performance of pigs fed either soy bean meal or soy protein concentrate.     

Immunocastrated male pigs: effect of 4 v. 6 weeks time post second injection on performance,carcass quality and meat quality

Immunocastration or vaccination against boar taint can be used as alternative for surgical castration of male piglets. The vaccine is administrated twice. After the second vaccination (V2), the pigs behave like barrows instead of boars and their feed intake increases which may result in a lower lean meat percentage. The timing of V2 is therefore crucial to find the right balance between the advantages of entire males and barrows. In this study, we evaluated the effect of time post second injection within the advised time frame (4 v. 6 weeks before slaughter) on behaviour, performance, carcass and meat quality of immunocastrated male pigs. In total, 180 animals (hybrid sow×Piétrain): 60 gilts, 60 male pigs vaccinated 6 weeks before slaughter (IM-6) and 60 male pigs vaccinated 4 weeks before slaughter (IM-4), all slaughtered at comparable slaughter weights. After 20 weeks of age, IM-6 showed more inactive behaviour at the expense of playing and aggressive behaviour. Daily feed intake (DFI), daily gain (DG) and feed conversion ratio (FCR) did not differ significantly between IM-6 and IM-4. Gilts had a lower DFI and DG in the late finishing phase and a higher FCR overall compared with both IM groups. Gilts showed a higher lean meat content compared with both IM groups. Earlier vaccination increased dressing percentage, which could partly be explained by the lower weight of the gastrointestinal tract, but not by testes weight. Meat quality traits and palatability did not differ significantly between IM-6 and IM-4. Vaccination of immunocastrates at 6 compared with 4 weeks before slaughter improved the calmness in the stable and the dressing percentage, while maintaining performance and carcass characteristics.     

Lysine requirements of imported European pigs in the humid lowland tropics from 23 to 62 kg liveweight

The responses of 144 Large White × Landrace pigs (72 castrated males and 72 females; mean initial liveweight approximately 23 kg) to graded additions of L-lysine monohydrochloride to a basal diet containing yellow maize and groundnut meal and 180 g crude protein per kg were studied. Total dietary lysine levels ranged from 5–12 g kg^?1. All diets contained digestible energy of 15.44–16.02 MJ kg^?1 DM. The pigs were individually fed from 23 to 33, 47 or 62 kg liveweight. Growth performance, carcass characteristics, nitrogen retention and plasma urea concentration were employed as response criteria. Influence of sex on lysine requirements for optimum growth, nitrogen retention and efficiency of essential amino acids utilization measured by minimum plasma urea concentration was also investigated.Supplementing the basal diet with L-lysine monohydrochloride significantly (P < 0.001) improved growth performance. Castrated male pigs grew faster and responded better to dietary lysine supplementation than gilts. No apparent decline in lysine requirements for optimum growth performance was observed for the two sexes of pigs as they got older. Optimum growth performance in castrated males was obtained with 9, 8 and 8 g lysine kg^?1 diets for the liveweight ranges 23–33, 23–47 and 23–62 kg, respectively. Optimum growth performance of the gilts for all three liveweight ranges was obtained at an estimated dietary lysine concentration of 11 g kg^?1.Optimum lean deposition, carcass leanness and other carcass measurements were obtained at 8 g lysine kg^?1 diet. Carcass data were not analysed for influence of sex.Plasma urea concentration showed further evidence of a quicker and cheaper indirect index of dietary amino acid adequacy in pigs. Minimal plasma urea concentration was obtained at 7–8 g lysine kg^?1 diet for the three liveweight ranges investigated.In a humid tropical environment, such as Ibadan, the dietary lysine requirement of Large White × Landrace pigs of 23–62 kg is about 9 g lysine kg^?1 diet for optimum growth performance and carcass quality, but nitrogen metabolism and plasma urea data suggest a lower level of to 7–9 g lysine kg^?1 diet.     

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

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

Evaluation of Florina (Pelagonia) sheep breed for growth and carcass traits

Two experiments were conducted to evaluate the performance of growing Florina (Pelagonia) lambs fed a high concentrate diet, as well as the effect of slaughter weight on carcass characteristics. The assessment of the growth used 12 male and 12 female individually penned weaned lambs until they reached 60% of their mature body weight (BW), while assessment of the effect of slaughter weight at weaning (42 days of age), and at 30%, 45% and 60% of the mature BW, on carcass characteristics used 40 male and 40 female weaned lambs. In experiment 1, results showed that Florina lambs have good growth. Male lambs grew faster (P < 0.001) than female lambs, resulting in a lower (P < 0.001) feed conversion ratio (FCR) for males. Rate of gain, feed consumption and FCR increased (P < 0.001) as the experiment progressed. In experiment 2, results showed that degree of maturity affected (P < 0.001) fasted body weight and carcass weight, as well as all carcass characteristics and commercial cuts, except the steaks cut which did not differ. Florina lambs can be slaughtered in heavier carcass weights, heavier than the 15 kg as the present practice. The heavier carcasses can appeal to wider range of consumers due to the excellent muscle development and the reduced visible fat cover. Florina sheep raised for heavy carcass meat production may be more economically beneficial for the breeders and the increased meat produced locally can help reduce need for importing meat from abroad.     

Multiple trait model combining random regressions for daily feed intake with single measured performance traits of growing pigs

A random regression model for daily feed intake and a conventional multiple trait animal model for the four traits average daily gain on test (ADG), feed conversion ratio (FCR), carcass lean content and meat quality index were combined to analyse data from 1 449 castrated male Large White pigs performance tested in two French central testing stations in 1997. Group housed pigs fed ad libitum with electronic feed dispensers were tested from 35 to 100 kg live body weight. A quadratic polynomial in days on test was used as a regression function for weekly means of daily feed intake and to escribe its residual variance. The same fixed (batch) and random (additive genetic, pen and individual permanent environmental) effects were used for regression coefficients of feed intake and single measured traits. Variance components were estimated by means of a Bayesian analysis using Gibbs sampling. Four Gibbs chains were run for 550 000 rounds each, from which 50 000 rounds were discarded from the burn-in period. Estimates of posterior means of covariance matrices were calculated from the remaining two million samples. Low heritabilities of linear and quadratic regression coefficients and their unfavourable genetic correlations with other performance traits reveal that altering the shape of the feed intake curve by direct or indirect selection is difficult.     

The effect of immunization against GnRF on nutrient requirements of male pigs: a review

In most countries, male pigs are physically castrated soon after birth to reduce the risk of boar taint and to avoid behaviours such as fighting and mounting. However, entire male pigs are more feed efficient and deposit less fat than barrows. In addition, many animal welfare organizations are lobbying for a cessation of castration, with a likelihood that this could lead to inferior pork unless an alternative method is used to control boar taint. An alternative to physical castration is immunization against gonadotrophin releasing factor (GnRF) which allows producers to capitalize on the superior feed efficiency and carcass characteristics of boars without the risk of boar taint. From a physiological perspective, immunized pigs are entire males until shortly after the second dose, typically given 4 to 6 weeks before slaughter. Following full immunization, there is a temporary suppression of testicular function and a hormonal status that resembles that of a barrow. Nutrient requirements will be different in these two phases, before and after full immunization. Given that there have been few published studies comparing the lysine requirements of entire males and barrows in contemporary genotypes, it is useful to use gilt requirements as a benchmark. A series of meta-analyses comparing anti-GnRF immunized boars and physical castrates and use of nutritional models suggest that the lysine requirement of entire males before the second immunization is 5% higher than for gilts, from 25 to 50 kg BW, and by 8% from 50 to 95 kg. Given that the penalty in growth performance for having inadequate dietary lysine is greater in males than in gilts or barrows, it is important to ensure that lysine requirements are met to obtain the maximum benefits of entire male production during this phase. After the second immunization, the lysine requirement of immunized males decreases and may become more like that of barrows. In addition, a consistent effect of full immunization is a marked increase in voluntary feed intake from about 10 days after the second dose. Putting these together, the estimated lysine requirement, expressed in terms of diet composition, falls to 94% of the gilt level. Although general principles can be described now, further research is needed to fully define the lysine requirements of immunized boars. It is important that the temporal pattern of tissue deposition rates and feed intake be explored to be incorporated into models to predict nutrient requirements over the period of rapidly changing metabolism.     

Effects of Dietary Chromium (III) Picolinate on Growth Performance,Respiratory Rate,Plasma Variables,and Carcass Traits of Pigs Fed High-Fat Diets

We investigated the effects of supplemental chromium (Cr) as Cr (III) picolinate on pigs fed high-fat diets (HFD) in a 56-day experiment. Thirty-two crossbred pigs (9.6 kg) were allotted to four treatments with four blocks and two pigs/pen. Treatments included: (1) low-fat diet (fat < 3.5%; LFD) with no Cr, (2) HFD (fat > 30%) with no Cr, (3) HFD with 1,000 ppb Cr, and (4) HFD with 2,000 ppb Cr. Pigs fed HFD gained weight faster, consumed less, and had lower feed:gain (p < 0.05). Pigs fed HFD had higher respiration rates than pigs fed LFD on d 41 (p < 0.05). Plasma insulin on d 14 linearly decreased with Cr (p = 0.05). Plasma cholesterol concentrations were higher in the pigs fed HFD than those fed LFD, but were largely unaffected by supplemental Cr. Consumption of HFD resulted in greater carcass weight, perirenal fat, and backfat measures (p < 0.01) compared with the LFD group. Cr resulted in linear reductions of hot carcass weight (p = 0.08) and average backfat (p < 0.05). The effects of Cr on carcass fat measures were more pronounced in castrated males than in females. These results indicate that Cr attenuates some effects of a HFD, mainly body fat accretion of pigs, and especially in castrated pigs.     

Feed intake patterns nor growth rates of pigs are affected by dietary resistant starch,despite marked differences in digestion

Current feed evaluation systems often assume that fermented starch (i.e. resistant starch (RS)) yields less energy than digested starch. However, growth rates of pigs fed low and high RS diets are often the same when feed is available ad libitum. This may be explained by its effect on digestive processes changing feeding behavior, and consequently energy utilization. This study aims to investigate the effect of RS on nutrient digestion and digesta passage rate in pigs, in combination with its effect on feeding behavior and growth performance under ad libitum conditions. In experiment 1, 20 male pigs (40 ± 2.82 kg) were fed diets containing either 50% waxy maize starch (low in RS (LRS)) or high-amylose maize starch (high in RS (HRS)), and soluble and insoluble indigestible markers. After 14 days of adaptation to the diets, pigs were fed hourly to reach steady state (6 h), dissected, and digesta were collected from eight segments. From the collected samples, nutrient digestion and passage rate of the solid and liquid digesta fraction were determined. In experiment 2, 288 pigs (80 ± 0.48 kg; sex ratio per pen 1 : 1; boar : gilt) were housed in groups of 6. Pigs were ad libitum-fed one of the experimental diets, and slaughtered at approximately 115 kg. Feed intake, growth and carcass parameters were measured. Ileal starch digestibility was greater for LRS-fed than for HRS-fed pigs (98.0% v. 74.0%; P < 0.001), where the additional undigested starch in HRS-fed pigs was fermented in the large intestine. No effects of RS on digesta passage rate of the solid or liquid digesta fraction and on feeding behavior were observed. Growth rate and feed intake did not differ between diets, whereas feed efficiency of HRS-fed pigs was 1%-unit higher than that of LRS-fed pigs (P = 0.041). The efficiency of feed used for carcass gain did not differ between diets indicating that the difference in feed efficiency was determined by the non-carcass fraction. Despite a 30% greater RS intake (of total starch) with HRS than with LRS, carcass gain and feed efficiency used for carcass gain were unaffected. RS did not affect digesta passage rate nor feeding behavior suggesting that the difference in energy intake between fermented and digested starch is compensated for post-absorptively. Our results indicate that the net energy value of fermented starch currently used in pig feed evaluation systems is underestimated and should be reconsidered.     

Effect of compensatory growth on performance, carcass composition and plasma IGF-1 in grower finisher pigs

A total of 48 female pigs (Large White × Landrace × Duroc cross) were used to determine whether a compensatory feed regime influenced performance, carcass composition and the level of plasma IGF-1. Pigs of initial age 73 days were fed a commercial diet at 0.70 of ad libitum (R) for 40 days followed by a return to ad libitum feeding for a further 42 days. The control group was fed ad libitum (A) throughout. Groups of animals on R and A feed regimes were slaughtered at the end of restriction period (SL1), 2 days after refeeding ad libitum (SL2) to establish the more immediate effects of refeeding on IGF levels, and after 42 days refeeding (SL3; n = 8 for each group). As expected, during the restriction period, average daily live weight gain in all the slaughter groups of R pigs was significantly lower than A pigs (P < 0.01); there was no significant difference in feed conversion ratios. In the re-alimentation period of SL3, R pigs grew 12.9% faster (P = 0.033), indicating compensatory growth. At SL1, there was a trend for carcass weight (P = 0.108) of A pigs to be higher than R pigs, but at SL2 live weight and carcass weight of A pigs were significantly heavier than R pigs (P < 0.05), but not at SL3. For killing-out percentage, there was no difference in SL1. After refeeding for 2 days (SL2) and 42 days (SL3), R pigs had significantly lower killing-out percentage than A pigs (P < 0.05). As a proportion of live weight, R pigs had smaller heart, kidney and liver (P < 0.05) than A pigs at SL1. At SL2, only the kidney was smaller in the restricted group (P < 0.05) and there were no significant differences in SL3. As a proportion of carcass weight, Longissimus dorsi was heavier in the R pigs at SL1 (P = 0.108) and SL2 (P < 0.05), but not at SL3. At SL1, there was a trend for intramuscular fat of A pigs to be higher than R pigs. The plasma IGF-1 level was lower in R pigs than A pigs (P = 0.010) at SL1, and slightly lower at SL2 (P = 0.110), with no significant differences at SL3. Dietary restriction period influenced plasma IGF-1 levels, which returned to the ad libitum group levels when animals were refed, as did live weight and carcass weight. It appears that the internal organs and possibly fat, but not muscles, underwent a compensatory response when animals were refed.     

土著发酵床对商品猪生产性能和血液生化指标的影响

目的采集徐州当地土著微生物作为原始菌株制作发酵床,考察土著发酵床对商品猪生产性能及血液生化指标的影响。方法选择60头杜×长×大三元配套系仔猪进行实验,仔猪断奶日龄为21 d。实验组商品猪饲喂于发酵床猪舍,对照组饲喂于水泥地面猪舍。每组设3个重复,每个重复随机选取健康仔猪10头。仔猪饲喂125 d后考察土著发酵床对商品猪生产性能和血液生化指标的影响。结果土著发酵床具有一定提高商品猪日增重的效果,并可显著降低料重比（P〈0.05）,但对猪酮体品质未产生显著影响。在血液生化指标方面,实验组商品猪血液中的总蛋白、白蛋白、碱性磷酸酶含量均显著高于对照组（P〈0.05）。结论土著发酵床可以提高猪的生长性能和免疫机能。     

Birth weight and postnatal dietary protein level affect performance, muscle metabolism and meat quality in pigs

Intrauterine growth restriction (IUGR), resulting in low birth body weight (LBW) occurs naturally in pigs. However, IUGR may also cause persistent changes in physiology and metabolism resulting in poorer performance, organogenesis and meat quality. As IUGR pigs have a lower daily gain from birth to slaughter they may differ in utilization of nutrients and requirements for dietary protein compared with their larger littermates. Thus, the objective in this study was to examine the interaction between birth body weight (BW) and the postnatal dietary protein level, in relation to postnatal performance, organogenesis, muscle metabolism and meat quality. The experiment was carried out with offspring from 16 purebred Danish Landrace gilts mated to Danish Landrace boars. The female and entire male pigs with LBW that survived at weaning were compared with the female and male pigs with the highest/high birth body weight (HBW) within each litter. The offspring were reared individually from weaning and were fed ad libitum a diet containing either a normal level of protein (NP) for optimal growth or an isocaloric diet containing a 30% lower protein content (LP) from 3 weeks to 150 days of age. At slaughter, we found no interactions between birth weight group and dietary protein level for any of the measured traits. The relative crown-rump length (cm/kg) at birth indicates that LBW pigs were thinner than HBW pigs. Daily gain and feed intake were reduced by 14% and 10%, respectively, while the kg feed/kg gain was slightly increased by 3% in LBW pigs compared with HBW pigs. The LP diet reduced daily gain by 27% due to reduced feed intake and increased kg feed/kg gain by 12% and 21%, respectively compared with the NP diet. LBW male pigs produced meat with a higher shear force than male HBW pigs and also LP pigs produced meat with higher shear force than NP pigs. The activity of lactate dehydrogenase in the Longissimus dorsi muscle (LD) was reduced in pigs fed the LP diet. Calpastatin was increased in LD of LBW pigs and decreased in pigs fed the NP diet. In conclusion, these results suggest a rejection of our hypothesis that low birth weight littermates have a lower requirement for dietary protein compared with heavy weight littermates. Furthermore, LBW male pigs and LP fed pigs of both genders produced less tender meat than HBW pigs or NP fed pigs, respectively.     

Growth performance, carcass characteristics and meat quality of group-penned surgically castrated, immunocastrated (Improvac®) and entire male pigs and individually penned entire male pigs

The objective of the study was to compare growth performance, carcass characteristics, meat quality and fatty acid composition of the adipose tissue of group-penned barrows, immunocastrated boars and entire males. Furthermore, the effect of housing of entire males on the aforementioned parameters was evaluated. At 55.2 days of age, 52 Swiss Large White pigs were blocked by litter and assigned by BW to four experimental groups: barrows (C), immunocastrated boars (IC), entire males (EMG) reared in group pens and entire males (EMP) reared in individual pens. In experiment 1, the effects of the method of castration were investigated (experimental groups C, IC and EMG). In experiment 2, the effects of housing on entire male pigs were evaluated (experimental groups EMG and EMP). All pigs had ad libitum access to standard diets from weaning to 107 kg BW. The two vaccinations (Improvac®) were applied to the IC pigs at an average BW of 22.6 and 73.0 kg. In experiment 1, average daily gain (ADG) did not (P > 0.05) differ among the experimental groups. However, EMG consumed less feed and had a better feed-conversion ratio than C (P < 0.001 for each). For IC, intermediate values were observed, which differed (P < 0.001) from EMG and C. Lean meat percentage decreased (P < 0.05) from EMG to IC, and from IC to C. The androstenone and skatole levels were higher (P < 0.05) in the adipose tissue of EMG than IC and C. Shear force values were higher (P < 0.01) in the longissimus muscle of C and EMG, compared to IC. The concentration of saturated fatty acid in the adipose tissue increased (P < 0.001) from EMG to IC, and from IC to C pigs, and that of polyunsaturated fatty acid decreased (P < 0.001). In experiment 2, ADG did not (P > 0.05) differ between EMP and EMG. However, EMP pigs consumed more feed than EMG pigs and had a poorer feed efficiency (P < 0.01 for each). In conclusion, EMG pigs had a better feed efficiency than IC pigs and their carcasses were leaner, but the risk of boar tainted pork was elevated. Group-housing negatively affected average daily feed intake but not ADG of entire males. At the moment, immunocastration offers a good approach to avoid castration and minimize the risk of boar taint.     

Influence of sex and gonadal hormones on rat-liver and carcass lipids during the development of an essential fatty acid deficiency

1. Groups of intact male and female rats and castrated rats injected with oestradiol or testosterone were given a diet containing hydrogenated coconut oil for 9 weeks, and at intervals the amounts and fatty acid compositions of the carcass and liver lipids were determined. 2. Male rats grew faster and larger, and exhibited typical external essential fatty acid deficiency symptoms sooner than did females. Testosterone-treated castrated male rats were similar to males, and oestradiol-injected castrated male rats resembled females. 3. Intact females maintained a higher linoleic acid concentration in their carcass than did males. Total amounts of carcass linoleic acid remained similar for all groups, only 200mg. being removed in 9 weeks regardless of body size. 4. The amounts of total cholesteryl esters were independent of liver size. They were higher in males and testosterone-treated castrated male rats than in females and oestrogen-treated castrated male rats. 5. Phospholipids represented about 80% of the liver lipids. The total amounts of the phospholipid linoleic acid and arachidonic acid were similar for all groups regardless of liver size, and were not affected appreciably by the deficiency. Females and oestrogen-treated castrated male rats maintained a higher proportion of phospholipid arachidonic acid for longer periods than did their male counterparts. Both the total amounts and the proportions of eicosatrienoic acid and palmitic acid were higher in males than in females. 6. Supplementation of the essential fatty acid-deficient diet with linoleic acid caused a rapid loss of eicosatrienoic acid and palmitic acid with a concomitant increase in stearic acid and arachidonic acid. 7. There were no obvious differences in the way that the essential fatty acids were metabolized or mobilized from adipose tissue of male or female rats during essential fatty acid deficiency. 8. The results indicated that the greater growth rate of the male rats caused them to require and synthesize more phospholipids than did the females. In the absence of adequate amounts of arachidonic acid, eicosatrienoic acid was substituted into the additional phospholipid. The earlier symptoms of essential fatty acid deficiency in the male rat could therefore be ascribed to the higher tissue concentrations of this unnatural phospholipid and its inability to perform the normal metabolic functions of phospholipids.     

Effects of immunization against GnRH, melengestrol acetate, and a trenbolene acetate/estradiol implant on growth and carcass characteristics of beef heifers

A 2 x 3 factorial experiment was conducted to determine the effects of an implant (trenbolene acetate/estradiol or no implant) and method of estrus suppression (immunization against GnRH, melengestrol acetate, or no suppression) on growth performance and carcass characteristics of heifers fed for slaughter. At the start of a 21-d feed adaption phase, crossbred beef heifers (n = 144, 390+/-2.8 kg) were given their first dose of an anti-GnRH vaccine or started on melengestrol acetate (MGA). Thereafter, heifers were fed a high-concentrate diet (78% barley grain) for 84 d (Days 0 to 83), received implants on Day 0, a second vaccination on Day 21, and were slaughtered on Days 84 or 85. Implanting increased average daily gain (1.72 vs 1.50 kg/d, P < 0.01), feed efficiency (6.02 vs 6.75 kg dry matter intake/kg gain, P < 0.01), preslaughter weight (532 vs 513 kg, P < 0.01), carcass weight (301 vs 289 kg, P < 0.01), and ribeye area (88.6 vs 85.9 cm2, P < 0.05), but had no affect (P > 0.05) on dry matter intake, grade fat thickness, marbling score, or lean yield. Compared to heifers fed MGA, those immunized against GnRH had a greater ribeye area (90.0 vs 84.6 cm2) and lean yield (63 vs 61%), and had thinner grade fat (7.5 vs 8.6 mm; P < 0.05 for each). Furthermore, immunized heifers had lower (P < 0.001) plasma progesterone concentrations than control heifers on Days 42, 63 and 83. Heifers fed MGA had less estrus mounting activity (P < 0.05) and lower plasma progesterone concentrations (P < 0.001) than the remaining heifers. Method of estrus suppression did not affect (P > 0.05) preslaughter weight, average daily gain, dry matter intake, feed efficiency, carcass weight, or marbling score. In conclusion, implanting significantly increased growth performance and preslaughter and carcass weights. Compared to heifers fed MGA, immunization against GnRH significantly increased ribeye area and lean yield, and reduced grade fat thickness