The effect of dietary ractopamine concentration and duration of feeding on growth performance, carcass characteristics, and meat quality of finishing pigs

A total of 400 barrows from Dekalb EB and 83 terminal sires mated to 43 and 45 maternal lines were used to evaluate the effects of dietary ractopamine (RAC; Paylean, Elanco Animal Health, Greenfield, IN) concentrations (0, 5, 10, or 20 ppm; as-fed basis) and feeding durations (6 to 34 d) on growth, efficiency, carcass, and meat quality characteristics of finishing pigs. Barrows were weighed and sorted into five weight blocks, each block consisting of 16 pens (five pigs per pen). Weight blocks were allocated to feeding duration treatments and assigned consecutively by weight from lightest to heaviest to represent 34, 27, 20, 13, and 6 d on test, respectively. The lightest and heaviest blocks averaged 79.8 and 103.8 kg, respectively, at the start of the test. Within a weight block, pens (four per treatment) were randomly assigned to one of four dietary concentrations of RAC in a basal diet containing 18.5% CP and 1.13% lysine. The experiment-wide target slaughter weight was 109 kg, and pigs and feeders were weighed weekly. Weight blocks (80 barrows per block) were slaughtered at a commercial packing plant after 6, 13, 20, 27, or 34 d on test. Overall, RAC supplementation improved (P < 0.05) ADG; however, ADG was not different (P > 0.08) from controls for pigs fed 5, 10, and 20 ppm RAC for 27, 34, and 6 d, respectively. During each feeding period, RAC-fed pigs had improved (P < 0.05) G:F, and, after 20, 27, and 34 d on test, pigs fed 20 ppm RAC had greater (P < 0.05) G:F compared with those fed 0 or 5 ppm RAC. Hot carcass weight was increased (P < 0.05) by RAC feeding after 13 and 27 d of feeding, and by feeding 10 and 20 ppm RAC after 20 d of feeding. After 34 d, pigs fed 20 ppm RAC had heavier (P < 0.05) hot carcass weight than pigs fed 10 ppm RAC. Fat-free lean estimates and the 10th-rib LM area were increased (P < 0.05) by feeding 10 and 20 ppm RAC after 27 d, and by feeding 20 ppm RAC after 34 d compared with controls. Japanese and American color scores, as well as L*, a*, and b* values of the LM, were not affected (P > 0.11) by 5 and 10 ppm RAC compared with controls during each feeding period. Visual marbling score for the LM was decreased (P < 0.05) when RAC was fed at 10 and 20 ppm compared with 0 ppm RAC when fed for 34 d. Dietary RAC improved growth performance at all feeding durations, whereas carcass composition was improved at longer feeding durations. In addition, 5 and 10 ppm RAC did not affect objective and subjective measures of pork quality.     

Supplementation of different fat sources affects growth performance and carcass composition of finishing pigs

Background: There are various fat sources with different energy values and fatty acid compositions that may affect growth performance and carcass composition of grow-finishing pigs. A higher net energy was recently reported in choice white grease compared with soybean oil. Therefore, two experiments were conducted to determine whether practical responses confirm that difference between choice white grease and soybean oil, and to extend the observations to other fat sources.Results: In Exp. 1, pigs fed fats had lower(P 0.05) average daily feed intake in phase II and overall period,greater(P 0.05) gain:feed in phase I, phase II, and overall period than pigs fed the control diet. Pigs fed fats tended(P = 0.057) to have thicker backfat depth at the last rib than those fed control. Pigs fed 6% fats had greater(P 0.01) gain:feed in phase II and overall period than pigs fed 3% fats. During phase I, pigs fed choice white grease grew faster(P 0.05) than pigs fed soybean oil. In Exp. 2, pigs fed dietary fats(soybean oil, choice white grease, animal-vegetable blend, palm oil, or tallow) had greater(P 0.01) gain:feed in each phase and overall period, greater(P 0.01) average daily gain in phase I, but lower(P 0.01) average daily feed intake in phase II an overall than pigs fed the control diets. The choice white grease also increased(P 0.05) average daily gain during phase I compared with soybean oil. Pigs fed palm oil had thicker(P 0.05) backfat depth at the 10 thrib than those fed soybean oil, animal-vegetable blend, or tallow.Conclusions: Inclusion of 6% dietary fat improved feed efficiency of finishing pigs, while different fats produced different practical results that may be consistent with their different energy values. Results from the early stage indicate that dietary fats with relatively more saturated fatty acids may provide greater energy than those with relatively more unsaturated fatty acids for growing pigs.     

Impact of dietary energy level and ractopamine on growth performance, carcass characteristics, and meat quality of finishing pigs

A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high, 3,537; medium, 3,369; and low, 3,317 kcal of ME/kg) to determine the effects of dietary ractopamine and various energy levels on growth performance, carcass characteristics, and meat quality of finishing pigs. High-energy diets were corn-soybean-meal-based with 4% added fat; medium-energy diets were corn-soybean meal based with 0.5% added fat; and low-energy diets were corn-soybean meal based with 0.5% added fat and 15% wheat middlings. Diets within each ractopamine level were formulated to contain the same standardized ileal digestible Lys:ME (0 mg/kg, 1.82; and 7.4 mg/kg, 2.65 g/Mcal of ME). Individual pig BW and feed disappearance were recorded at the beginning and conclusion (d 21) of the study. On d 21, pigs were slaughtered for determination of carcass characteristics and meat quality. No ractopamine × energy level interactions (P > 0.10) were observed for any response criteria. Final BW (125.2 vs. 121.1 kg), ADG (1.2 vs. 1.0 kg/d), and G:F (0.31 vs. 0.40) were improved (P < 0.001) with feeding of ractopamine diets. Feeding of the low-energy diet reduced (P = 0.001) final BW and ADG compared with the high- and medium-energy diets. Gain:feed was reduced (P = 0.005) when the medium-energy diets were fed compared with the high-energy diets. Additionally, G:F was reduced (P = 0.002) when the low-energy diets were compared with the high- and medium-energy diets. Feeding ractopamine diets increased (P < 0.05) HCW (93.6 vs. 89.9 kg) and LM area (51.2 vs. 44.2 cm(2)). The LM pH decline was reduced (P ≤ 0.05) by feeding ractopamine diets. The feeding of low-energy diets reduced (P = 0.001) HCW when compared with the high- and medium-energy diets and reduced (P = 0.024) 10th-rib backfat when compared with the high- and medium-energy diet. These data indicate that feeding ractopamine diets improved growth performance and carcass characteristics, while having little or no detrimental effect on meat quality. Reductions in energy content of the diet by adding 15% wheat middlings resulted in impaired ADG, G:F, and 10th-rib backfat. There were no ractopamine × energy level interactions in this trial, which indicates that the improvements resulting from feeding ractopamine were present regardless of the dietary energy levels.     

Effects of dietary lysine and energy density on performance and carcass characteristics of finishing pigs fed ractopamine

Two hundred sixteen crossbred barrows and gilts (84.3 kg BW) were used to test the effects of dietary energy density and lysine:energy ratio (Lys:ME) on the performance, carcass characteristics, and pork quality of finishing pigs fed 10 ppm ractopamine. Pigs were blocked by BW and gender, allotted to 36 pens (six pigs per pen), and pens were assigned randomly within blocks to dietary treatments (as-fed basis) arranged in a 2 x 3 factorial design, with two levels of energy (3.30 or 3.48 Mcal/kg) and three Lys:ME (1.7, 2.4, or 3.1 g lysine/Mcal) levels. Pigs were fed experimental diets for 28 d, and weights and feed disappearance were recorded weekly to calculate ADG, ADFI, and G:F. Upon completion of the feeding trial, pigs were slaughtered and carcass data were collected before fabrication. During carcass fabrication, hams were analyzed for lean composition using a ham electrical conductivity (TOBEC) unit, and loins were collected, vacuum-packaged, and boxed for pork quality data collection. Energy density had no (P > 0.22) effect on ADG or ADFI across the entire 28-d feeding trial; however, pigs fed 3.48 Mcal of ME were more (P < 0.02) efficient than pigs fed 3.30 Mcal of ME. In addition, ADG and G:F increased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. Carcasses of pigs fed 3.48 Mcal of ME were fatter at the last lumbar vertebrae (P < 0.08) and 10th rib (P < 0.04), resulting in a lower (P < 0.03) predicted fat-free lean yield (FFLY). Conversely, 10th-rib fat thickness decreased linearly (P = 0.02), and LM depth (P < 0.01) and area (P < 0.01) increased linearly, with increasing Lys:ME. Moreover, FFLY (P < 0.01) and actual ham lean yield (P < 0.01) increased as Lys:ME increased in the diet. Dietary energy density had no (P > 0.19) effect on pork quality, and Lys:ME did not (P > 0.20) affect muscle pH, drip loss, color, and firmness scores. Marbling scores, as well as LM lipid content, decreased linearly (P < 0.01) as Lys:ME increased from 1.7 to 3.1 g/Mcal. There was a linear (P < 0.01) increase in shear force of cooked LM chops as Lys:ME increased in the finishing diet. Results indicate that 3.30 Mcal of ME/kg (as-fed basis) is sufficient for optimal performance and carcass leanness in pigs fed ractopamine. The Lys:ME for optimal performance and carcass composition seems higher than that currently used in the swine industry; however, feeding very high Lys:ME (> 3.0 g/Mcal, as-fed basis) to ractopamine-fed pigs may result in decreased marbling and cooked pork tenderness.     

甜菜碱和B族维生素对商品猪生长性能及同体肉品质影响

许多研究表明,甜菜碱可以促进肥育猪生长,改善饲料利用率,降低背膘厚,减少胴体脂肪沉积,增大眼肌面积和提高瘦肉率。日粮中添加B族维生素,可     

Effects of a "step-up" ractopamine feeding program, sex, and social rank on growth performance, hoof lesions, and Enterobacteriaceae shedding in finishing pigs

Increasing concern for animal well-being and food safety has stimulated the investigation of feed additives such as ractopamine (RAC), a beta-agonist widely used to improve production performance of finishing pigs. The objective of this study was to determine effects of RAC feeding, delivered as a "step-up" program (5 mg/kg for 2 wk followed by 10 mg/kg for 2 wk), on growth performance, Enterobacteriaceae shedding, including Salmonella, and hoof lesions, also taking into account sex and social rank of pigs. A total of 64 barrows and gilts (balanced by treatment and sex) were assigned to pens of 4 (by sex) as either control (CTL) or RAC treatment. Social ranks (dominant, intermediate, and subordinate) of pigs in each pen were determined by behavioral observation during 48 h post-mixing. Fecal samples were collected once per week for 5 wk. At slaughter, the 32 dominant and subordinate barrows and gilts (16/sex) were examined for hoof lesions, and luminal contents from ileum, cecum, and rectum were collected. Pigs fed RAC had increased growth performance (P < 0.05) with social rank of animals affecting overall ADG (P < 0.05). Gilts gained more backfat than barrows when comparing to baseline values at both 10th and last ribs (P < 0.05), whereas loin eye area increased at a similar rate for both barrows and gilts (P > 0.10). No significant effect of RAC feeding was found on backfat or loin eye area (P > 0.10). At slaughter, RAC-fed pigs had greater BW (P < 0.05). Despite the positive effects of RAC feeding on growth performance, pigs fed the compound had a greater frequency of front and rear hoof lesions as did barrows and dominant individuals (P < 0.05). Detectable concentrations of Salmonella shedding were not identified at any time during the experiment. Enterobacteriaceae shedding concentrations from RAC-fed pigs peaked at the first week of feeding and progressively decreased until slaughter. At slaughter, rectal and cecal Enterobacteriaceae concentrations were less in RAC-fed pigs than in CTL pigs (P < 0.05). Social rank tended to affect gut Enterobacteriaceae populations of barrows more than in gilts (P < 0.10). The effects of RAC feeding on hoof soundness and Enterobacteriaceae populations in the gastrointestinal tract of finishing pigs warrant further investigation. It is also proposed that the integration of the social rank status of the individual into future studies should be considered, because it may affect treatment responses.     

液态饲喂在育肥猪上的使用效果

为研究饲料液态饲喂对育肥猪生长性能和经济效益的影响,试验选用体重为(82.93±3.35) kg的"杜×长×大"(Duroc×Landrace×Yorkshire)三元杂交猪300头,随机分为3组,每组5个重复,每个重复20头猪,试验期为31 d,对照组饲喂固体颗粒饲料,试验A组用对照组日粮加水饲喂,试验B组日粮由干料、过期酸奶、水按比例配制而成,干基营养水平与对照组相当。试验结果表明:相比对照组,试验A组的平均日增重、平均日采食量分别提高了6.9%和2.1%,料重比降低了4.3%,但两组之间差异不显著;试验B组的平均日增重与对照组相当,平均日采食量、料重比分别降低了6.3%(P<0.05)和6.4%(P>0.05);同时,饲喂液态料的两个试验组经济效益均有不同程度提高。     

Effects of dibutyryl cAMP on growth performance and carcass traits in finishing pigs

This study was designed to investigate the effects of dietary supplementation with N⁶, 2′-O-dibutyryl adenosine 3′,5′-cyclic monophosphate (dbcAMP) on growth performance, carcass traits, histochemical characteristics and serum constituents in finishing pigs. Seventy-two Duroc × (Landrace × Large White) barrows (57.3 ± 0.6 kg) were randomly allotted to 3 treatments with 6 replicate pens/treatment (4 pigs/pen). The pigs were fed diets containing 0, 10 and 20 mg dbcAMP/kg, respectively, until the final slaughter weight of approximately 90 kg. There were no differences in growth performance among dietary treatments. Leaf fat proportion and first rib backfat thickness were reduced (P < 0.05), whereas tenth rib backfat thickness tended to decrease (P = 0.10), in pigs fed 10 mg dbcAMP/kg. Lean percentage was greater (P < 0.05) and longissimus muscle area tended to increase (P = 0.10) in pigs fed 10 mg dbcAMP/kg when compared to the control group, but hot carcass weight was not affected by dbcAMP. Growth rate of fat-free lean tissues tended to increase (P = 0.09) in dbcAMP-supplemented pigs. Dietary dbcAMP decreased (P < 0.05) adipocytes diameter in subcutaneous fat, whereas longissimus muscle fiber diameter tended to increase (P = 0.06) with dbcAMP supplementation; however, no difference in longissimus muscle cell density was detected among treatments. Serum concentrations of total protein and 3′,5′-cyclic adenosine monophosphate increased (P < 0.05) in response to dbcAMP, but concentrations of triglycerides, total cholesterol, glucose and urea in serum did not differ among dietary treatments. These results indicate that dbcAMP had a positive effect on carcass traits. Addition of 10 mg dbcAMP/kg to the diet was beneficial for growth performance and lean percentage, as well as improving protein and fat metabolism.     

甜菜碱对生长肥育猪生产性能、胴体性状及血清生化指标的影响

本试验选用 1 8头体重约 2 8kg的杜× (大×长 )三元杂交猪 ,随机分为 2组 ,分别饲喂添加0 ,1g/kg甜菜碱 (以纯品计 )的玉米—豆粕型饲粮 (生长、肥育期粗蛋白水平分别为 1 7 0 %、1 5 0 % ,消化能浓度为 1 3 3 0MJ/kg) ,直至体重约 96kg左右结束。结果表明 ,甜菜碱有提高生长猪(约 2 8～ 60kg)日增重和饲料转化率的趋势 ,对采食量无显著影响 ,不影响血清钙、镁、钾、钠、氯、尿素氮浓度。肥育猪 (约 60～ 96kg)的日增重和饲料转化率因甜菜碱添加而有降低趋势 ,采食量不受影响。甜菜碱不影响肥育猪血清镁、钾、钠、尿素氮浓度 ,但对氯、钙浓度有影响。纵观全期 ,甜菜碱不影响生长肥育猪全期的生产性能。甜菜碱提高了屠宰率 (P <0 0 5) ,同时胴体瘦肉率有增加趋势 ,脂肪率有降低趋势 ,其余胴体性状无显著差别。以上结果提示 ,在本试验条件下 ,在生长肥育猪全期添加甜菜碱对生产性能无显著影响 ,但对胴体品质可能有一定的提高。     

Effect of group size and feeder type on growth performance and feeding patterns in finishing pigs

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in 208 crossbred finishing pigs (equal numbers of barrows and gilts) between 84.4 (SD = 0.81) to 112.8 (SD = 1.08) kg BW over a 4-wk period. Pigs were given ad libitum access to a corn-soybean meal-based diet (15.9% CP; 0.79% lysine; 3,328 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Growth rates were not different for the two feeder types; however, feed intake was lower and gain:feed ratio higher for pigs on the FIRE feeders (P < 0.01). Feed intake, growth rate, and gain:feed ratio were not different (P > 0.05) among the group sizes. Number of feeder visits per day decreased and feed intake per visit, feeder occupation time per visit, feed consumption rate, and percentage of time the feeder was occupied increased with group size (P < 0.05). Feed intake per visit had the strongest correlation with daily feed intake (r = 0.54; P < 0.01) and was negatively correlated with gain:feed ratio (r = -0.38; P < 0.01). However, the correlations between growth performance and other feeding pattern traits were relatively weak (r < or = 0.30). As group size increased, diurnal variation in number of feeder visits and feed consumed per hour decreased. There was no difference in time spent sitting and standing between the two feeder types. The proportion of time spent eating was generally lower for the larger groups on both feeders. The proportion of time spent lying was similar across group sizes for pigs on the conventional feeders but was greater for pigs in the larger groups on the FIRE feeders. This study suggests that finishing pigs can maintain feed intake and growth rate by changing feeding behavior as group size increases from 2 to 12.     

Effects of ractopamine, genotype, and growth phase on finishing performance and carcass value in swine: I. Growth performance and carcass merit

A replicated factorial experiment using 183 individually fed crossbred barrows was conducted. Pigs were fed an 18.5% CP (.95% lysine) diet with 3,594 kcal of ME/kg. The effects of five genotypes (GT): 1) Hampshire (H) x (H x Duroc [D]), 2) synthetic terminal sire line, 3) (H x D) x (Landrace [L] x [Yorkshire (Y) x D]), 4) L x (Y x D), and 5) Y x L; two levels of ractopamine (RAC) treatment: 0 and 20 ppm; and three treatment weight periods (WT): 1) 59 to 100, 2) 73 to 114, and 3) 86 to 127 kg live weight on growth performance and carcass traits were evaluated. Ractopamine increased (P less than .0001) amount (FSL) and percentage (PFSL) of carcass lean standardized to 10% fat content, loin eye area (LEA), and dressing percentage (PDRES) and reduced (P less than .01) amount (DF) and percentage (PDF) of dissected fat. Magnitudes of RAC effects were smaller than those reported by other researchers. Effects of GT and WT on all growth and carcass traits were highly significant (P less than .001) except for those of WT on ADG (P less than .05) and GT on average feed intake (AFI) and backfat thickness at the last rib (BFLR; P less than .05). Genotype 3 performed better for most economically important traits than did GT 1 and 4, suggesting that heterosis existed in GT 3, which essentially was obtained by crossing GT 1 and 4. Among the three treatment periods, WT 2 had the highest ADG. As BW increased from WT 1 to 3, AFI and AFI/ADG ratio (FCR) increased and lean percentage decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

饲料中添加紫花苜蓿多糖对育肥猪生长性能和胴体品质的影响

为研究紫花苜蓿多糖对育肥猪生长性能及胴体品质的影响,选择体重相近的健康三元杂交育肥猪180头,随机分成3组,每个组3个重复,每个重复20头,1组饲喂基础日粮为对照组,2、3组分别在基础日粮中添加5.0%、10.0%紫花苜蓿多糖,预试验10 d,试验期60 d。在试验1 d和60 d测定生长性能指标,试验结束测定胴体品质。结果表明:(1)试验2、3组试验末重和平均日增重分别较对照组提高5.8%、6.2%、14.0%、14.9%(P <0.05),试验2、3组料重比分别较对照组降低4.6%、5.0%(P <0.05)。(2)试验2、3组屠宰率和瘦肉率分别较对照组提高4.2%、4.0%、5.8%、6.9%(P <0.05);试验2、3组胴体率均高于对照组(P> 0.05),试验2、3组背膘厚和眼肌面积分别较对照组降低7.8%、10.0%、8.9%、8.7%(P <0.05)。(3)试验2、3组肉质评价指标大理石评分、肉色、剪切力、p H24 h较对照组相比,均差异性不显著(P> 0.05)。综述所述,日粮中10.0%紫花苜蓿多糖可以提高育肥猪的生长性能和胴体品质。     

Effect of heat stress and feeding management on growth performance and physiological responses of finishing pigs

This study aimed to determine whether pig responses to heat stress (HS) were directly due to heat exposure (regardless of feeding level and pattern) or were indirectly due to the reduction of feed intake (FI) and to determine if increasing feeding frequency (splitting heat increments) can improve pig response to HS. A total of 48 pigs (66.1 ± 1.7 kg) were allocated to four groups in three replicates. After 7 d in thermoneutral (TN) conditions (22 °C; period 1 [P1; day −7 to −1]), pigs were placed in either TN or HS (32 °C) conditions for 20 d (period 2 [P2; day 0 to 19]). The diet was provided either ad libitum (AL; 2 distributions/d) or pair-fed (PF8; 8 distributions/d) using HS–AL pigs as the reference group. Thus, the four experimental groups were TN–AL, HS–AL, TN–PF8, and HS–PF8. The daily ration of PF8 pigs was distributed at every 90-min intervals from 0900 to 1930 hours. Data were analyzed using the PROC MIXED procedure with replicate (n = 3), experimental group (n = 4), and their interactions as fixed effects, and the REPEATED statement was used for repeated measures data. Pigs had a similar average daily feed intake (ADFI) during P1 (P > 0.05). In P2, HS–AL and PF8 pigs had lower ADFI (−19%), average daily gain (−25%), and final body weight (−6.1 kg) than TN–AL pigs (P < 0.01). TN–AL pigs had thicker backfat than TN–PF8 pigs (P < 0.05), while the HS pigs had intermediate results. HS pigs had a higher perirenal fat percentage based on the contrast analysis between PF8 pigs (P < 0.05). Thermoregulatory responses of pigs increased with HS exposure but did not differ between HS or between TN groups (P > 0.05). For TN pigs, variation in muscle temperature (T_muscle) depended on feeding and physical activity, while for HS pigs, T_muscle gradually increased throughout the day. The T_muscle of PF8 pigs increased with each additional meal but plateaued earlier for HS–PF8 than TN–PF8 pigs; an increase in T_muscle per meal was also lower in HS–PF8 than TN–PF8 (P < 0.05). Exposure to HS decreased plasma T3 and T4 (P < 0.05) and increased plasma creatinine (P < 0.05). Between the PF8 groups, HS pigs also had a transient increase in plasma insulin on day 8 (P < 0.05). The effect of HS on FI decreased the growth rate of pigs but there are heat-induced effects, such as altered physiological responses, which might explain the direct HS effects seen in other literature especially in terms of increased adiposity. The increased feed provision frequency in the present study did not improve the HS response of pigs.     

合生素对育肥猪生长性能影响的研究

本试验为验证合生素对育肥猪生长性能的影响,采用56日龄,平均体重为33±0.78kg的健康育肥猪96头,按体重相近原则随机分为2组,每组6个重复,每个重复8头猪,对照组饲喂添加抗生素(5mg/kg黄霉素)的基础日粮,试验组饲喂添加0.1%合生素的基础日粮。试验结果表明:试验组中育肥猪的平均日增重、料肉比和腹泻猪头数与对照组相比略有改善,但差异不显著(P>0.05)。合生素在育肥猪日粮中的最适添加量有待于进一步研究。     

Effect of supplemental vitamins and trace minerals on performance and carcass quality in finishing pigs

Two trials with finishing pigs (PIC line 355 x Camborough 22) were conducted to evaluate the effects of vitamin and trace mineral (VTM) supplement deletions on performance, carcass quality, and tissue nutrient levels. Trial 1, a 3 x 2 factorial arrangement of treatments involving three VTM supplement regimens and two stress regimens, was conducted for 12 wk with 252 pigs (mixed sex). Average initial weight of pigs was 54 kg. The VTM regimens consisted of control (adequate level of VTM throughout trial), VTM deleted for the final 6 wk, and VTM deleted for entire 12 wk of the trial. The stress regimens consisted of leaving half the treatments in their original location or moving the other half of the treatments to a new pen location every 3 wk. There were three replications (pens) per treatment with 14 pigs per pen (0.80 m2). Diets were medicated with bacitracin methylene disalicylate. Overall, there were no treatment differences (P > 0.05) for ADG, ADFI, gain:feed ratio, longissimus muscle area, or last-rib backfat. However, there was a greater than 75% decrease (P < 0.001) in vitamin E content of longissimus muscle from deleting VTM for 6 or 12 wk. Trial 2, a 3 x 2 factorial arrangement of treatments involving three VTM regimens and two genders, was conducted for 12 wk with 306 pigs. Average initial weight of pigs was 58 kg. The VTM regimens were identical to those used in Trial 1. Each treatment consisted of three gender replications of 17 pigs per pen (0.66 m2), and all diets were unmedicated. Overall, pigs fed diets without VTM for 12 wk had lower (P < 0.06) ADG than those fed the control diets. Vitamin E content of the ham muscle was reduced by greater than 50% (P < 0.001) when pigs were fed diets without VTM for 6 or 12 wk compared with those fed the control diet. Concentrations of copper in ham muscle were reduced (P < 0.05) in pigs fed diets without VTM. These data suggest that deleting VTM during the finishing stage markedly lowers the vitamin E content of pork muscle.     

Impact of betaine on pig finishing performance and carcass composition

Two experiments were conducted to evaluate the effect of betaine supplementation of finishing diets on growth performance and carcass characteristics of swine. Experiment 1 included 288 pigs in a 2 x 2 x 3 factorial arrangement of treatments consisting of barrows and gilts of two genetic populations fed diets with 1.25 g/kg supplemental betaine from either 83 or 104 kg to 116 kg and control pigs fed betaine-devoid diets. Pigs were housed three pigs per pen with eight replicate pens per treatment. Diets were corn-soybean meal-based with 300 ppm added choline. Genetic populations differed (P < 0.05) in fat depth (2.24 vs 2.93 cm) and longissimus muscle depth (53.8 vs 49.1 mm) at 116 kg. Betaine reduced feed intake (P < 0.05); however, real-time ultrasound measurements were not affected. In Exp. 2, 400 pigs were used in a 2 x 2 x 2 factorial arrangement of treatments to evaluate the effect of sex (barrow or gilts), betaine (0 or 1 g/kg of diet), and crude protein (CP) (0.70% lysine = 12.7% CP or 0.85% lysine = 15.0% CP) when fed from 60 to 110 kg live weight. Pigs had been assigned to either a high- or low-protein feeding regimen at an average initial weight of 11.3 kg and were maintained on their respective protein levels throughout the experiment. For a 56-d period from 61.7 kg to 113.6 kg, pigs were fed diets with 300 ppm added choline. Within each protein level, pigs were randomly assigned to diets containing 0 or 1 g/kg betaine. Pigs were group-housed (four to five pigs per pen). Pig weight and feed intake were recorded every 28 d. Real-time ultrasound measurements were recorded initially and at d 28 on 64 pigs, and on all pigs prior to slaughter. Growth rate was fastest and feed intake greatest for barrows (P < 0.05) and for pigs receiving 12.7% crude protein. A crude protein x betaine interaction (P < 0.05) was observed from d 28 to 56 with pigs fed the 15% CP diet growing fastest when supplemented with 1 g/kg betaine, and pigs receiving the 12.7% CP diet growing fastest when the diets contained 0 g/kg betaine. Gilts more efficiently (P < 0.05) converted feed into body weight gain, as did pigs receiving the 12.7% CP diet (P < 0.05). Longissimus muscle area and fat measurements were unaffected by betaine or dietary protein on d 28. However, by d 56 betaine reduced average fat depth in barrows (P < 0.05; 3.21 vs 3.40 cm), but not in gilts. Betaine may be more effective at altering body composition in barrows than in gilts.     

三阶段和四阶段肥育法对猪生产性能和胴体组成的影响

以32头“杜长大”三元杂交仔猪作为试验动物，研究三阶段和四阶段肥育法对于猪生产性能和胴体组成的影响。结果表明，与三阶段肥育法相比，四阶段肥育法有利于提高日增重和饲料转化率，节约饲料成本，但差异不显著（P＞0.05)，对胴体组成也没有显著影响（P＞0.05)。     

高活菌发酵饲料对生长肥育猪生产性能的影响

选用240头日龄相近、体况一致的杜×长×大三元杂交肥育猪,随机平均分为3个处理,对照组、试验1组和试验2组。对照组饲喂基础日粮加抗生素,试验1组和试验2组分别在基础日粮中添加4%和8%的高活菌发酵饲料。试验结果表明:在28d的饲养试验中,试验2组饲养效果最好,平均日增重比对照组提高12.34%,采食量增加7.90%,料肉比减少4.0%,腹泻率降低2.89%。应用高活菌发酵饲料饲喂生长肥育猪能起到促进其生长、减少腹泻以及改善仔猪肠道健康的功效。     

不同梯度发酵豆粕对育肥猪生长性能、胴体性状及肉品质的影响

试验旨在研究不同梯度发酵豆粕等量替代普通豆粕对育肥猪生长性能、胴体性状及肉品质的影响.采用单因素完全随机试验设计,选择240头初始体重(61.25±2.31) kg的杜×长×大育肥猪,随机分为6组,每组8个重复,每个重复5头猪.对照组育肥猪饲喂玉米-豆粕型基础日粮,5个试验组依次采用5％、7％、9％、11％、13％...     

Effects of dietary iodine value product on growth performance and carcass fat quality of finishing pigs

A total of 120 barrows (initial BW = 47.9 ± 3.6 kg; PIC 1050) were used in an 83-d study to determine the effects of dietary iodine value (IV) product (IVP) on growth performance and fat quality. Pigs were blocked by BW and randomly allotted to 1 of 6 treatments with 2 pigs per pen and 10 pens per treatment. Dietary treatments were fed in 3 phases and formulated to 3 IVP concentrations (low, medium, and high) in each phase. Treatments were 1) corn-soybean meal control diet with no added fat (low IVP), 2) corn-extruded expelled soybean meal (EESM) diet with no added fat (medium IVP), 3) corn-soybean meal diet with 15% distillers dried grains with solubles and choice white grease (DDGS + CWG; medium IVP), 4) corn-soybean meal diet with low CWG (medium IVP), 5) corn-EESM diet with 15% DDGS (high IVP), and 6) corn-soybean meal diet with high CWG (high IVP). On d 83, pigs were slaughtered and backfat and jowl fat samples were collected and analyzed. The calculated and analyzed dietary IVP values were highly correlated (r(2) = 0.86, P < 0.01). Pigs fed the control diet, EESM, or high CWG had greater (P < 0.05) ADG than pigs fed EESM + DDGS. Pigs fed the control diet had greater (P < 0.05) ADFI than pigs fed all other diets. Pigs fed EESM + DDGS and high CWG had improved (P < 0.05) G:F compared with pigs fed the control diet or DDGS + CWG. Pigs fed diets with DDGS had greater (P < 0.05) backfat and jowl fat IV, C18:2n-6, and PUFA and less SFA than pigs fed all other treatments. Pigs fed EESM had greater (P < 0.05) backfat and jowl fat IV, C18:2n-6, and PUFA than pigs fed the control diet, low CWG, or high CWG. Pigs fed low CWG or high CWG had greater (P < 0.05) jowl fat IV than control pigs. Feeding ingredients high in unsaturated fatty acids, such as DDGS and EESM, had a greater impact on fat IV than CWG, even when diet IVP was similar. Therefore, IVP was a poor predictor of carcass fat IV in pigs fed diets with different fat sources and amounts of unsaturated fats formulated with similar IVP. Dietary C18:2n-6 content was a better predictor of carcass fat IV than diet IVP.