Effects of increasing lysine on carcass composition and cutting yields of immunologically castrated male pigs

The objective of this experiment was to determine if increasing lysine in the diets of immunologically castrated (IC) male pigs would increase percentage fat free lean and carcass cutting yields when compared with physical castrates. The anti-gonadotropin-releasing factor (GnRF) immunological product (Improvest, Pfizer Animal Health) is used worldwide to immunologically castrate entire male pigs to control boar taint and take advantage of the inherent ability of the entire male to deposit more muscle, less fat, and grow more efficiently than physically castrated males. The immunization process essentially allows the pig to grow as an entire male pig for most of its life and then removes any boar odor (boar taint) before slaughter. Reported lean meat advantages may also provide economic benefits to the domestic meat industry. Approximately 1,200 male pigs [physical castrates, IC males, and entire males] were each assigned to 1 of 4 diet programs which differed in lysine content. In each case, lysine was fed in a conventional step-down program that culminated with the following concentrations in the late finishing diet: physical castrates fed low lysine (0.7%), IC fed low lysine (0.7%), IC fed low/medium lysine (0.8%), IC fed medium/high lysine (0.9%), IC fed high lysine (1.0%), and entire males fed high lysine (1.0%). At 25 wk of age (5 wk post-second injection), pigs were individually weighed and the 2 pigs (n=96) in each pen closest to the median pig BW were selected and slaughtered. The right side of each carcass was dissected into soft tissue, skin, and bone. Proximate composition was determined on the soft tissue to determine percentage fat-free lean. The left side of each carcass was weighed and initially fabricated into ham, loin, belly, and whole shoulder. Each primal piece was weighed again and further fabricated into respective subprimal cuts. Immunological castration did not change (P>0.05) shear force values or ultimate pH when compared with either physical castrates or entire males. Marbling appeared to decrease as dietary lysine was increased among IC males. As expected, IC males had a greater (P<0.05) percentage fat-free lean than physical castrates but less (P<0.05) than entire males. Immunologically castrated males fed diets with medium/high and high lysine had greater (P<0.05) lean cutting yields and carcass cutting yields than physical castrates. Lean cutting yield and carcass cutting yields appeared to increase as dietary lysine was increased among IC males. Overall, immunological castration improved carcass cutability, increased percentage fat free lean, and had no effect on pork quality when compared with physical castrates.     

Effects of increasing lysine on further processed product characteristics from immunologically castrated male pigs

The objective of this experiment was to determine if increasing lysine in the diets of immunologically castrated (IC) male pigs would affect further processed product characteristics when compared with physical castrates or entire males. Raw materials for this experiment were derived from a previous experiment evaluating carcass characteristics. Physical castrates, IC males, and entire males were assigned to 1 of 4 diet programs with increasing lysine in a step-down lysine inclusion program that culminated with the following concentrations in the late finishing diet: physical castrate with low lysine (0.7%), IC with low lysine (0.7%), IC with low/medium lysine (0.8%), IC with medium/high lysine (0.9%), IC with high lysine (1.0%), and entire with high lysine (1.0%). Bellies were injected with a cure solution to a target of 110% of original green weight, and weighed again to determine brine uptake. Hams were injected with same cure solution to a target of 130% of green weight. Cure solution was formulated for a finished product inclusion of 1.5% salt, 0.34% phosphate, 0.05% sodium erythorbate, 0.11% sugar, and 0.014% sodium nitrate. Physical castrates had thicker (3.77 cm) bellies (P<0.05) than all treatment groups, except IC males fed low/medium lysine (3.73 cm). Entire males (2.85 cm) had the thinnest (P<0.05) bellies of all treatment groups. There were no differences (P>0.05) in percentage brine uptake for cured bellies among IC males regardless of dietary lysine (range 9.93 to 10.67%). Cooked yield of cured bellies was not different (P>0.05) among physical castrates or IC males regardless of lysine inclusion. Cooked yield of cured bellies from entire males (95.12%) was less (P<0.05) than cooked yield for any other treatment group. Pumped weight differences of cured hams among treatment groups were similar to green weight differences, and there were no differences (P>0.05) among any treatment groups for pump uptake percentage. There were also no differences in cook loss percentages among any treatment group. Therefore, differences in cooked yield are a reflection of initial green weight. There were no differences (P>0.05) for protein fat-free values among any treatment groups. Therefore, it can be concluded, in this population of pigs, there were no differences in further processed product characteristics among physical castrates and IC males.     

Interactive effect of ractopamine and dietary fat source on quality characteristics of fresh pork bellies

Crossbred pigs (n = 216) were used to test the interaction, if any, of ractopamine (RAC) and dietary fat source on the characteristics of fresh pork bellies. Pigs were blocked by BW (77.6 +/- 6.5 kg) and allotted randomly to pens (6 pigs/pen). After receiving a common diet devoid of RAC for 2 wk, pens within blocks were assigned randomly to 1 of 4 treatments arranged in a 2 x 2 factorial design, with 5% fat (beef tallow vs. soybean oil) and RAC (0 vs. 10 mg/kg). At the conclusion of the 35-d feeding period, pigs were slaughtered at a commercial pork packing plant (average BW of 108.8 +/- 0.6 kg), and fresh bellies were captured during carcass fabrication. Neither RAC (P = 0.362) nor fat source (P = 0.247) affected belly thickness. Subjective (bar-suspension) or objective (compression test) measures of belly firmness were not (P > or = 0.148) affected by the inclusion of RAC in the diet; however, bellies from pigs fed soybean oil (SBO) were softer than those from pigs fed beef tallow (BT), as indicated by perpendicular (P < or = 0.005) and parallel (P < 0.001) suspensions. Moreover, bellies from BT-fed pigs required more (P = 0.096) force to compress 50% of their thickness than bellies from SBO-fed pigs (52.29 vs. 43.51 kg). Color (L*, a*, and b* values) of the belly lean and fat was not (P > or = 0.131) affected by RAC, and lean color was similar (P > or = 0.262) between fat sources; however, belly fat from BT-fed pigs was lighter (P = 0.030) and redder (P = 0.013) in color than belly fat from SBO-fed pigs. Bellies of SBO-fed pigs had greater (P < 0.001) proportions of PUFA and lower (P < 0.001) proportions of SFA and MUFA than belly fat from pigs fed BT. Regardless of the RAC inclusion level, PUFA:SFA and iodine values were lower in belly fat from pigs fed BT than SBO; however, within SBO-fed pigs, PUFA:SFA and iodine values were further increased by feeding RAC (RAC x fat source, P < 0.001). As expected, dietary fat source altered the fatty acid composition of fresh pork bellies, which subsequently impacted fresh belly firmness. Interestingly, including RAC in swine finishing diets exacerbated the effect of feeding SBO on pork fat polyunsaturation.     

The effect of ractopamine hydrochloride on the carcass cutting yields of finishing swine.

This study was designed to evaluate growth performance, carcass cutting yield, and processing characteristics of boneless hams and bellies from finishing pigs fed diets containing 0, 5, 10, or 20 ppm of the phenethanolamine ractopamine hydrochloride (RAC). Sixty pigs were blocked by starting weight and randomly assigned to pens (four pigs/pen) within each of three blocks. Treatments were then randomly assigned to the pens to total six pens of the 0-ppm level and three pens each at the 5-, 10-, and 20-ppm RAC levels. Weight gain and feed consumption were monitored and animals were slaughtered by weight block after approximately 48 d on trial. Slaughter weight, ADG, and feed/gain were improved (P less than .05) for RAC treatments. Dressing percentage was higher and increased linearly (P less than .05) for RAC treatments. Carcass weight, length, leaf fat weight, backfat thickness, loin eye area, and color, marbling, and firmness of the longissimus were evaluated. The RAC-treated carcasses were heavier (P less than .05) and loin eye area increased linearly (P less than .05). One side of each carcass was fabricated using National Association of Meat Purveyors specifications. Trimmed hams and loins from the RAC treatments were heavier (P less than .05) than those from control animals. No differences (P greater than .05) in carcass cutting yield (percentage of trimmed primal cuts) were observed between treatments. However, trimmed hams and loins from the 20-ppm RAC treatment represented a greater (P less than .05) percentage of carcass weight than did those from control animals. Ractopamine did not affect raw belly or bacon characteristics (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Performance of male pigs immunized against GnRH is related to the time of onset of biological response

In this study, the performance of male pigs immunized against GnRH was determined in relation to the onset of their biological response to the immunization. Pigs were immunized at 9 and 17 wk of age and were housed in a pen together with both a surgically castrated and an intact boar littermate. Feed intake was restricted to 2.8 to 3.2 times maintenance requirement for energy. Animals were weighed weekly and slaughtered at 108 kg BW. Depending on the time of onset of the response after immunization in terms of biological effects, immunized pigs were retrospectively grouped into two categories. One category consisted of the immunized pigs, which had undetectable or low levels of LH and testosterone at the time of booster immunization-known as "early" responding immunocastrates (E-IM, n = 8), whereas the "late" responding immunocastrates (L-IM, n = 7) had substantial LH and testosterone levels at that time. This dichotomy of the response to immunization also was reflected in testis weight, with 17 g and 40 g for E-IM and L-IM pigs, respectively. At slaughter, testis size and weight were reduced (P < 0.001) in the immunocastrated pigs as compared to the intact boars. Androstenone concentrations in backfat of all immunocastrated pigs were undetectable. Growth performance (i.e., ADG and feed efficiency [FE, g gain/kg feed]), was better in boars and L-IM pigs than in surgical castrates and E-IM pigs (P < 0.05). Average daily gain and FE did not differ between E-IM pigs and the surgical castrates, but intact boars performed better than L-IM (P < 0.02). There were no significant differences in carcass quality (backfat thickness and meat percentage) between boars and surgical castrates at slaughter. However, for both characteristics L-IM pigs and intact boars performed better (P < 0.03) than E-IM pigs. Thus, growth performance in L-IM is better than in either E-IM or surgical castrates.     

Influence of sex and castration of females on growth performance and carcass and meat quality of heavy pigs destined for the dry-cured industry

Crossbred pigs (n = 240) from Pietrain x Large White sires mated to Landrace x Large White dams, with an average age of 100 d (60.5 +/- 2.3 kg of BW), were used to investigate the effects of sex and slaughter weight (SW) on growth performance and on carcass and meat quality characteristics. There were 6 treatments arranged factorially, with 3 classes (intact females, IF; castrated females, CF; and castrated males, CM) and 2 slaughter weights (114 and 122 kg of BW). Each of the 6 combinations of treatments was replicated 4 times, and the experimental unit was a pen with 10 pigs. Castrated males and CF ate more feed, grew faster, and had more carcass backfat depth and fat thickness at the gluteus medius muscle but lower loin yield than IF (P < 0.05). In addition, CF and CM had more intramuscular fat (P < 0.05) and less linoleic acid content in the subcutaneous fat (P < 0.01) than IF. Pigs slaughtered at 122 kg of BW had lower ADG (P < 0.05), decreased G:F (P < 0.05), and more gluteus medius fat than pigs slaughtered at 114 kg of BW (P < 0.05). It was concluded that CF and CM had similar productive performance and meat quality characteristics when slaughtered at the same age, and that castration of females improved ADG and increased weight and fat content of primal cuts with respect to IF. Therefore, castration of females is recommended in pigs destined for the dry-cured industry because of the beneficial effects on quality of the primal cuts.     

Effects of L-carnitine supplementation on quality characteristics of fresh pork bellies from pigs fed 3 levels of corn oil

Crossbred pigs (n = 216) were used to test the effect of supplemental L-carnitine (CARN) on the fatty acid composition and quality characteristics of fresh pork bellies from pigs fed diets formulated with different inclusion levels of corn oil. Pigs were blocked by BW (43.6 ± 1.0 kg) and allotted randomly to pens of 6 pigs within blocks. Then, within blocks, pens were assigned randomly to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement, with either 0 or 100 mg/kg of supplemental CARN and 3 dietary inclusion levels (0, 2, or 4%) of corn oil (CO). When the lightest block weighed 125.0 kg, all pigs were slaughtered, and left-side bellies were captured during carcass fabrication for quality data collection. Fresh pork bellies were evaluated for length, width, thickness, and firmness (bar-suspension and Instron-compression methods) before a 2.5-cm-wide strip of belly was removed and subsequently dissected into subcutaneous fat, primary lean (latissimus dorsi), secondary lean (cutaneous trunci), and intermuscular fat for fatty acid composition determination. Although belly length, width, and thickness of fresh pork bellies were not affected by CARN (P ≥ 0.128) or CO (P ≥ 0.073), belly firmness decreased linearly (P < 0.001) with increasing dietary CO, but there was no (P ≥ 0.137) effect of CARN on any belly firmness measure. Dietary CARN increased (P < 0.05) the proportion of total SFA in the intermuscular fat layer, increased (P < 0.05) the proportion of total MUFA in the primary and secondary lean layers, and decreased (P < 0.05) the proportion of total PUFA in the intermuscular fat and secondary lean layers of pork bellies. Moreover, the SFA and MUFA compositions decreased linearly (P < 0.001) with increasing dietary CO, and the rate of the decrease in SFA composition was greater (P < 0.001) in the fat layers than the lean layers. Conversely, the PUFA content increased linearly (P < 0.001) with increasing dietary CO, and the rate of the increase in PUFA was greater (P < 0.001) in the fat than the lean layers, and greater (P = 0.022) in the primary than secondary lean layer. Results from this study would indicate that differences in the amount and rate of fatty acid deposition associated with feeding increased amounts of CO, along with moisture differences among the belly layers, combine to negatively affect fresh pork belly firmness.     

Bromocriptine-induced reduction of body fat in pigs

An experiment was conducted with 36 crossbred finishing pigs (18 male castrates and 18 females) to evaluate the effect of bromocriptine implants on growth, feed intake, feed efficiency, plasma urea nitrogen (PUN) and carcass characteristics. Three levels of bromocriptine (0, 5 and 10 mg/[pig.d]) were administered, via implants at the base of the ear, to six (two replicates of three) male castrates or to six (two replicates of three) intact female pigs (2 x 3 factorial arrangement of treatments). Average initial weight of pigs at the time of implantation was 89.7 kg, and the implants remained in the pigs for 28 (replicate 1) or 30 (replicate 2) d prior to slaughter. Gain, feed intake and efficiency of feed utilization were not affected (P greater than .10) by bromocriptine. Plasma urea nitrogen was lower in female pigs administered 10 mg bromocriptine; bromocriptine did not affect PUN of male pigs (gender x bromocriptine, P less than .08). Tenth rib fat thickness and average backfat thickness were lower (P less than .06) and percentage of muscling was higher (P less than .06) in pigs implanted with bromocriptine. Female pigs had less 10th rib fat but larger loin eye areas and a greater percentage of muscling than male pigs.     

Effect of age at slaughter on carcass traits and meat quality of Italian heavy pigs

Barrows and gilts (n = 128) from four breed crosses were used to investigate the effect of age at slaughter on carcass traits, proteolytic enzyme activity, and meat and fat quality. Pigs were blocked by breed cross into four blocks, and within blocks, one pen (eight barrows and eight gilts) was assigned randomly to be slaughtered at either 8 or 10 mo of age. Pigs were fed a corn-barley-soybean meal finisher diet from 104 +/- 2.5 d of age (37.7 +/- 0.33 kg BW) to the appropriate slaughter age. Carcasses from older (10 mo) pigs had lower (P < 0.01) muscularity indexes and lean cut yields than those of younger (8 mo) pigs, but dressing percentage and longissimus muscle area increased (P < 0.01) with age. Older pigs produced a redder (P < 0.01) and darker (P < 0.05) semimembranosus, with lower (P < 0.01) ultimate pH and cathepsin B and B + L activities, as well as higher (P < 0.01) aminopeptidase hydrolyzing activity than younger pigs. Moreover, the longissimus muscle of pigs slaughtered at 10 mo of age had lower (P < 0.01) drip and cooking loss percentages than that from pigs slaughtered at 8 mo of age. Ham subcutaneous fat from 10-mo-old pigs had greater (P < 0.05) percentages of oleic acid and lower (P < 0.01) proportions of moisture, linoleic, and linolenic acids than subcutaneous fat from pigs slaughtered at 8 mo of age. Results from this study indicate that fresh hams from pigs slaughtered at 10 mo of age would be more suitable for the production of high-quality, Italian, dry-cured hams.     

Effect of dietary potassium chloride on feeder pig performance, market shrink, carcass traits and selected blood parameters

A total of 288 commingled crossbred feeder pigs were purchased and transported 1,050 km in two trials to investigate the effect of added dietary potassium chloride in receiving and finishing diets on feeder pig shrink recovery, performance and pre-slaughter shrink. Diets containing 0, .48%, .96% or 1.44% added potassium chloride were fed for 2 wk post-arrival and again from 12 wk post- arrival until slaughter. There was no effect (P greater than .1) on gain (22.9 kg pay weight) or feed conversion or on plasma or red blood cell potassium for the 2-wk post-arrival period due to the inclusion of potassium chloride in the 2-wk receiving diet. Also, there was no effect (P greater than .1) of potassium chloride in diets from 12 wk post-arrival until slaughter on gain, feed conversion, market shrink, carcass dressing percentage and plasma or red blood cell potassium concentration at slaughter. These results suggest that corn-soybean meal-based diets contain sufficient potassium for pigs following a period of stress associated with marketing and transport.     

Comparison of varying doses and durations of ractopamine hydrochloride on late-finishing pig carcass characteristics and meat quality

The objective was to investigate the effect of various doses and durations of ractopamine hydrochloride (RAC) on pig HCW, cutting yields, and meat quality. Late-finishing pigs (approximately 93 kg) were allotted to 12 treatments 35 d before slaughter. Treatments consisted of negative control (NEG; 13.1% CP, 0.64 TID Lys), positive control (POS; 17.8% CP, 0.94 TID Lys), and 2 RAC doses (5 and 7.4 mg/kg) with 5 different feeding durations for each dose (7, 14, 21, 28, or 35 d). Pigs on ractopamine-duration diets were fed NEG until incorporation of RAC, and then the diet was switched to POS to comply with label requirements. A subset of 240 pigs was utilized to determine the effects of RAC on carcass cutting yields. This subset was selected by taking the 5 pigs closest to the average pen weight from 4 complete replicates. Differences in response to RAC between 5 and 7.4 mg/kg were not significant. Therefore, RAC dosages were pooled, resulting in an average dose of 6.2 mg/kg, which was then compared with NEG and POS diets. Ractopamine increased (P < 0.05) HCW by 2.5 and 2.3 kg compared with the NEG and POS diets, respectively. Hot carcass weight also increased linearly (P=0.003) as RAC duration increased. Indicators of carcass leanness increased with RAC compared with NEG. Estimated carcass lean percentage increased (P=0.010) 1 percentage unit from 54.79 to 55.79%, carcass cut yield increased (P<0.001) 1.23 percentage units from 50.61 to 51.84%, and (P=0.006) boneless lean cut yield increased 1.27 percentage units from 36.71 to 37.98%. Ractopamine decreased (P=0.002) subjective marbling scores 0.49 units from the NEG value of 3.0, but RAC did not differ (P=0.203) from POS. Subjective color values and shear force aging curves for RAC were not significantly different from NEG or POS. Overall, RAC had greater responses in carcass weight and cut yield than NEG, and had minimal effects on meat quality.     

Effect of split marketing on the welfare, performance, and carcass traits of finishing pigs

The aim of this study was to compare a split marketing (SM) strategy, in which the heaviest pigs in a group are removed and slaughtered earlier than the others, with an all-out (AO) marketing strategy, in which all pigs are removed from the pen simultaneously and slaughtered on the same day, in terms of welfare, performance, and carcass traits of noncastrated (i.e., intact) male and female pigs. The experimental treatments were arranged in a 2 × 2 factorial array with 1) marketing strategy (SM vs. AO) and 2) sex (males vs. females), which yielded 4 treatment groups of 14 pigs (73.1 ± 4.8 kg): male SM, male AO, female SM, and female AO (7 replicates/group). Pigs in AO groups were all slaughtered after 6 wk on trial, whereas in SM groups the 3 heaviest pigs were removed and slaughtered 2 wk before the remainder of the group, which were slaughtered at the same time as the AO pigs. Pigs were fed a liquid diet from a long trough 3 times daily. Behavioral observations were conducted before and after SM, the day of SM, and 1 and 2 wk later. Behavior was recorded both during and between feed events, and skin lesions were scored on all, except the 3 pigs removed from SM groups before and 2 wk after SM. Growth performance, feed efficiency, and carcass traits were recorded. The number of aggressive interactions during feed events decreased after the 3 pigs were removed from SM groups. This reduction in aggressive interactions was observed on the day of SM in male groups (before SM: 24.3 vs. the day of SM: 14.7, SED = 3.31, P < 0.05 for interaction) and in subsequent observations in female groups (before SM: 21.4 vs. days after SM: 13.4, SED = 3.31, P < 0.05 for interaction). However, SM had no effect on behaviors recorded between feed events or on the number and severity of skin lesions (P > 0.10). There were no differences between the 11 remaining pigs in SM groups and the 14 pigs in AO groups in terms of growth performance, feed efficiency, and carcass traits of female or intact male pigs (P > 0.10). However, reduced within-pen CV in carcass weight was detected in pigs from SM groups compared with pigs from AO groups (8.6 vs. 10.9, SEM = 0.72, P < 0.05). Therefore, in restrictively fed pigs, a SM strategy improved the welfare of both female and intact male pigs by reducing aggressive interactions during feeding but had no effect on performance or carcass traits.     

Influence of sex and castration on growth performance and carcass quality of crossbred pigs from 2 Large White sire lines

In total, 360 pigs slaughtered at 125 kg of BW and destined for the dry-cured industry were used to study the influence of sex and castration [immunocastrated males (IMC), surgically castrated males (CM), and intact females (IF)] in 2 terminal Large White sire lines [Top York (TY) and Tempo (TE)] on growth performance and carcass and meat quality. The female line was Large White × Landrace. The IMC pigs were immunized against gonadotropin-releasing factor (GnRF) with Improvac at 78 (experimental d 16) and 126 (experimental d 64, 48 d before slaughter) d of age. Each of the 6 treatments was replicated 6 times (10 pigs/pen). Through the day of the first Improvac injection (62 to 78 d of age), IMC and IF grew at a slower rate (P < 0.001) than CM with no differences (P = 0.95) in feed intake. The CM had greater G:F than IF, with IMC being intermediate (P < 0.01). From 78 to 126 d of age (between Improvac injections), the IMC pigs ate less feed (P < 0.001) and grew at a slower rate than CM, with IF being intermediate. The IMC pigs were more feed efficient than IF, and both were more efficient than CM (P < 0.001). However, from 126 to 174 d of age (from the second Improvac injection to slaughter), IMC pigs grew at a faster rate (P < 0.001) and were more efficient (P < 0.001) than IF and CM. Overall, IMC and CM pigs grew at a faster rate (P < 0.01) than IF, and IMC were more efficient than the other sexes (P < 0.001), but had reduced (P < 0.001) carcass yield compared with CM and IF. The IMC and IF pigs also had less (P < 0.001) backfat depth than CM. Intact females had greater (P < 0.01) loin yield but less intramuscular fat than IMC and CM and greater (P < 0.05) fresh and trimmed ham yields than CM, with IMC being intermediate. Crossbreds from TE sires grew at a faster rate (P < 0.001) than crossbreds from TY sires, but no differences (P = 0.23 and 0.14, respectively) were found for feed intake or efficiency. Crossbreds from TY produced greater (P < 0.05) fresh and trimmed ham yield, but less (P < 0.01) loin yield and intramuscular fat content than crossbreds from TE. In conclusion, IMC pigs are more efficient, but have less carcass yield than CM and IF. The intramuscular fat content is least for IF and similar for IMC and CM. Crossbreds from TE sires were larger and had greater intramuscular fat content, but slightly less trimmed ham yield compared with crossbreds from TY sires. Immunocastrated pigs can replace CM for the production of heavy pigs destined for the dry-cured industry. Because of increased carcass weight, crossbreds from TE sires may have an advantage over crossbreds from TY sires.     

A field trial to evaluate a Mycoplasma hyopneumoniae vaccine: effects on lung lesions and growth rates in swine.

A killed Mycoplasma hyopneumoniae vaccine was evaluated in a single swine herd in which the farrowing barn and weaner rooms were on one Mycoplasma-free farm, while the growing and finishing barn was on a separate farm on which Mycoplasma was present. The study was carried out in a cohort of pigs born in a 12-week period. Pigs born in 6 of the 12 wk were vaccinated and the rest were left as controls. The vaccine was administered twice at approximately 3 and 6 wk of age. Carcass characteristics, lung lesions, and growth rates were recorded on 893, 390, and 220 pigs, respectively. The vaccine reduced the prevalence of pneumonic lesions in slaughter hogs from 69% to 36% (P < 0.001). It also appeared to reduce the prevalence of pleuritis from 20% to 13%, but the difference was only statistically significant at P = 0.07. The vaccine had no effects on carcass characteristics except that carcasses of vaccinated pigs were, on average, 1 kg heavier than those of nonvaccinated pigs, and a smaller percentage of vaccinated pigs were shipped "light" (carcass weight < 70 kg). Two methods were used to estimate the effect of the vaccine on growth rates (as measured by days to 80 kg carcass weight) resulting in estimates of 11 and 2 d reduction attributable to vaccination, respectively. The latter estimate was probably an underestimate for reasons discussed in the paper.     

Danish investigations concerning body composition of pigs in relation to nutrition,sex and slaughter weight

Several Danish investigations were carried out in order to elucidate the influence of nutrition, sex and slaughter weight on the body composition in pigs. In this paper we discuss whether selection of breeding animals should be based mainly on: (1) per cent meat in the carcass, (2) a combination of per cent meat, daily gain and feed consumption per kg live weight gain, or maybe better, (3) a combination of per cent meat and feed consumption per kg meat produced.Investigations comprising five different energy and protein levels and 1100 pigs slaughtered at live weights varying from 80 to 120 kg showed that both feeding intensity and slaughter weight influenced the carcass composition. Increasing feeding intensity and increasing slaughter weight caused a deterioration in the ratio between meat and subcutaneous fat. The feeding intensity had only little influence on kg meat produced whereas increasing feeding intensity caused an increase in kg subcutaneous fat produced.The females contained more meat than did the male castrates. Besides, the deterioration in carcass composition due to increasing slaughter weight and feeding intensity were lower in the females than in the male castrates. Daily gain increased with increasing feeding intensity. The investigations indicate maximal protein synthesis to take place within the live weight area of 90–100 kg.High correlations were found between the chemical composition of the different anatomical fractions in 90-kg pigs. The empty pigs (live weight minus the content of the digestive tract) weighed on average 80.8 kg, of which 42.0% was dry matter. The dry matter contained 41.1% protein, 51.1% chemical fat, 7.7% ash and 7080 kcal per kg. The meat fraction contained 55% of the protein, 30% of the chemical fat and 38% of the energy in the empty pigs.     

Growth, development, and carcass composition in five genotypes of swine.

An experiment with 127 barrows representing five genotypes, 1) H x HD, 2) SYN, 3) HD x L[YD], 4) L x YD, and 5) Y x L (H = Hampshire, D = Duroc, SYN = synthetic terminal sire line, L = Landrace, and Y = Yorkshire), was conducted to evaluate growth and development of swine from 59 to 127 kg live weight. Animals were allowed ad libitum access to a pelleted finishing diet containing 18.5% CP, .95% lysine, and 10.5% fat, with an energy density of 3,594 kcal of ME/kg. Pigs were serially slaughtered at either 59, 100, 114, or 127 kg live BW. After slaughter, carcasses were chilled and backfat was measured at four locations. The right side of each carcass was fabricated into primal cuts of ham, loin, Boston Butt, picnic, and belly. Composition of each primal cut was determined by physical dissection into lean, fat, bone, and skin. Estimated allometric growth coefficients for carcass length, carcass weight, and longissimus muscle area relative to BW; carcass lean, fat, bone, and skin relative to both BW and carcass weight; and lean in each of the primal cuts relative to total carcass lean did not differ (P greater than .05) among genotypes. Relative to BW, the pooled growth coefficient(s) for carcass weight was (were) greater (P less than .001) than unity, whereas those for carcass length, longissimus muscle area, and backfat at first rib were smaller (P less than .001) than unity. Those for other backfat measurements were close to 1.00. Relative to either BW or carcass weight, the pooled coefficient(s) for fat was (were) greater (P less than .001) than unity, whereas those for lean, bone, and skin were smaller (P less than .001) than unity. Growth of lean, backfat, bone, and skin in the carcass were nearly linearly associated with increases in BW. The increase in fat weight was curvilinear as the pig grew and was accelerated in later growth stages, indicating that carcass fat percentage increased with increased BW.     

Effect of wean-to-finish management on pig performance

In each of three trials, 240 crossbred barrows weaned at 17 d of age (5.1 kg BW) were assigned to one of three experimental treatments based on light and heavy weight outcome groups. Experimental treatments were 1) wean-to-finish at 0.69 m2/pig and 15 pigs/pen; 2) wean-to-finish double-stocked at 0.35 m2/pig, 30 pigs per pen for 8 wk and then randomly split into two pens (either stayed in same pen or moved to new pen) for growth to slaughter at 0.69 m2/pig; and 3) nursery facility for 8 wk at 0.35 m2/pig and 15 pigs/pen followed by move to the same grow-finish facility housing wean-to-finish and double-stocked pigs and maintaining pen integrity. Beginning at 38 kg BW, diets were supplemented with either bacitracin methylenedisalicylate at 33 mg/kg to slaughter or tylosin at 44 mg/kg to 59 kg BW and 22 mg/kg thereafter. There were no trial x treatment interactions, even though there was considerable variation in health status among trials. At the end of the 56-d nursery period, wean-to-finish pigs weighed more than nursery (28.7 vs 27.7 kg; P = 0.071) and double-stocked pigs (28.7 vs 26.9 kg; P = 0.002), due to greater ADG (wean-to-finish vs nursery; P = 0.062; wean-to-finish vs double-stocked; P = 0.002) and greater ADFI (wean-to-finish vs nursery; P = 0.024; wean-to-finish vs double-stocked, P = 0.002). There was no effect of treatments (P > 0.1) on ADG, feed conversion, carcass lean percentage, or lean gain during the growing-finishing period. There was also no effect of treatment (P > 0.1) on ADG or ADFI from weaning to slaughter. There was no difference (P > 0.1) between bacitracin methylenedisalicylate and tylosin for ADG, feed conversion, carcass lean percentage, or daily lean gain. These data suggest that housing 5-kg weaned pigs in fully slatted growing-finishing facilities from weaning to slaughter was not detrimental to overall performance. In this experiment, dietary additions of bacitracin methylenedisalicylate or tylosin from 38 kg BW to slaughter weight resulted in similar growth performance.     

Slaughter value, meat quality, creatine kinase activity and cortisol levels in the blood serum of growing-finishing pigs slaughtered immediately after transport and after a rest period

The experimental materials comprised 44 hybrid [female (Polish Large White x Polish Landrace) x male Duroc] growing-finishing pigs. The animals were randomly divided into two groups: 24 pigs were slaughtered immediately after transport and 20 pigs were slaughtered after a 24-hour rest period in the lairage. The meat content of pork carcasses, carcass dressing percentage, the proximate chemical composition, physicochemical and sensory properties of meat and shear force values were determined. Serum creatine kinase activity and cortisol levels were determined in blood samples collected before transport and during carcass bleeding. Pigs slaughtered immediately after transport, compared with those slaughtered after a 24-hour rest period, were characterized by a higher meat content of the carcass and a higher carcass dressing percentage. Pre-slaughter handling had no effect on pork quality. The incidence of normal-quality meat, partially PSE (pale, soft, exudative) meat and PSE meat was similar in both groups. Chemical analysis showed that the content of dry matter, total protein, fat and minerals in meat was comparable in both groups. As regards the functional properties of the pork, samples from the carcasses of pigs that had rested before slaughter had a higher contribution of the red color component. Meat from pigs slaughtered immediately after transport had more desirable sensory properties. Pre-slaughter resting had a significant effect on those analyzed physiological parameters which were found to be good indicators of pre-slaughter stress. Serum creatine kinase activity and cortisol levels were higher in blood samples collected after transport (during carcass bleeding) than in samples collected before transport, pointing to a strong stress response of animals to pre-slaughter treatment. The decrease in serum cortisol levels in blood samples collected during bleeding from the carcasses of pigs slaughtered after a 24-hour rest period, compared with samples collected from animals slaughtered immediately after transport, suggests that rest before slaughter alleviated stress induced by pre-slaughter handling operations.     

The effects of gender and slaughter weight on the growth performance, carcass traits, and meat quality characteristics of heavy pigs

Crossbred pigs (n = 192) from Piétrain x Large White sires mated to Landrace x Large White dams, with a mean BW of 75 +/- 1.3 kg, were used to investigate the effects of gender and slaughter weight (SW) on growth performance, carcass characteristics, and meat quality. Pens of pigs (eight pigs/pen) were assigned randomly to one of six treatments arranged in a 2 x 3 factorial design with two genders (barrows or gilts) and three SW (116, 124, or 133 kg). Each treatment was replicated four times. Over the entire trial, barrows had higher (P < 0.001) ADFI (as-fed basis) and ADG than gilts; however, gilts had higher (P < 0.05) gain-to-feed ratios (G:F) than barrows. Barrows had lower (P < 0.01) dressing percents than gilts and produced fatter (P < 0.001) carcasses that had lower trimmed shoulder (P < 0.10) and ham (P < 0.001) yields than gilts. There was a trend for the semimembranosus muscle (SM) from barrows to have a higher (P < 0.10) 45-min pH than that of gilts, but 24-h pH was 0.11 pH unit higher (P < 0.01) in the SM of barrows than gilts. Gender had no (P > 0.10) effect on the moisture and lipid content of the longissimus muscle (LM), nor did gender affect (P > 0.10) LM color, myoglobin content, or thaw loss percentage. However, the LM from barrows had lower (P < 0.05) cooking loss percentages and tended to have lower (P < 0.10) shear force values than the LM from gilts. Pigs slaughtered at 116 kg had higher (P < 0.05) ADG than pigs slaughtered at 124 and 133 kg. Daily feed intake (as-fed basis) was not (P > 0.10) different among SW; however, pigs slaughtered at 116 and 124 kg had higher (P < 0.001) G:F than those slaughtered at 133 kg. Dressing percent, backfat depth, carcass length, and ham and shoulder weights increased (P < 0.001) as SW increased from 116 to 133 kg. The initial (45-min) pH of the SM from pigs slaughtered at 133 kg was higher (P < 0.05) than from pigs slaughtered at 116 or 124 kg; however, 24-h pH was not (P > 0.10) affected by SW. The LM from pigs slaughtered at 133 kg was darker (lower L* values; P < 0.001), redder (higher a* value; P < 0.01), and had more (P < 0.001) myoglobin than the LM of pigs slaughtered at 116 and 124 kg. Barrows and gilts of this particular crossbreed can be used to produce acceptable quality fresh pork when slaughtered at 116 kg; however, increasing SW to 124 kg, or more, decreased live pig performance and carcass leanness without any additional benefits to pork quality attributes.     

Effects of Duroc, Meishan, Fengjing, and Minzhu boars on carcass traits of first-cross barrows.

Duroc, Meishan, Fengjing, and Minzhu boars were mated to crossbred gilts during two breeding seasons. From each sire breed group each season, six pens of approximately eight barrows each were slaughtered. A pen of pigs from each sire breed group was slaughtered at 7-d intervals from 168 to 203 d of age each season. Breed of sire effects were significant for all age-adjusted carcass traits except carcass length, fat thickness at the last rib, color score, and firmness score. At 184 d of age, Duroc crosses had the heaviest (P less than .05) slaughter and carcass weights; Minzhu crosses were lighter (P less than .05) than Meishan crosses but not lighter than Fengjing crosses. Differences among age-constant traits reflect differences in BW. After adjustment to a constant carcass weight of 78 kg, the three Chinese breeds had very similar carcass characteristics. Carcasses sired by Durocs had significantly less backfat and larger longissimus muscle area than carcasses sired by the Chinese breeds. Weight of each trimmed wholesale lean cut and their total weight were significantly higher for Duroc crosses than for Chinese crosses. Breed of sire means did not differ significantly for belly weight, but Duroc crosses had less (P less than .05) weight of leaf fat. Relative to Chinese crosses, longissimus muscles from Duroc crosses had more marbling (P less than .05). Sire breed groups did not differ significantly for color or firmness score. Pigs sired by Meishan, Fengjing, and Minzhu produced carcasses with significantly less lean content at a carcass weight of 78 kg than did pigs sired by Duroc.