Response of growing-finishing pigs to decreasing floor space allowance and(or) virginiamycin in diet

Five hundred forty crossbred pigs were utilized in four trials (10 replications) at two stations to determine the separate and interacting effects of decreasing floor space allowance with or without the addition of virginiamycin to the diet on performance of growing-finishing pigs. Pigs were allowed .37, .33 or .28 m2/pig during the growing phase (23 to 55 kg) and .74, .66, .56 m2/pig during the finishing phase (55 to 100 kg) and fed either a corn-soybean meal control diet or the control diet plus 11 mg of virginiamycin/kg of diet. Floor space allowances were achieved by varying pen size, so the number of pigs and feeder space per pig were constant for all pens. During the growing phase, daily gain (P less than .01) daily feed intake (P less than .05) and feed conversion ratio (P less than .05) decreased as floor space allowance decreased. During the finishing phase and for the total test period, daily gain (P less than .01) and feed conversion ratio (P less than .05) were reduced but daily feed intake was not affected (P greater than .05) by restricted floor space allowance. The addition of virginiamycin to the diet had no effect on pig performance. The virginiamycin X floor space allowance interaction was not significant, suggesting that pigs fed a diet with or without virginiamycin responded similarly to restricted floor space allowance. The data suggest that the addition of virginiamycin to the diet was ineffective in overcoming the decrease in performance of growing-finishing pigs caused by crowded conditions.     

Effect of group size on performance of growing-finishing pigs

Six hundred forty growing-finishing pigs (initial BW = 23.2 +/- 4.8 kg) were used in a 12-wk study (final BW = 95.5 +/- 10.2 kg) to quantify the effects of group size (10, 20, 40, and 80 pigs/pen) on performance, tail biting, and use of widely distributed feed resources. One single-space wet/dry feeder was provided for every 10 pigs, and floor allowance was 0.76 m2/pig in all treatment groups. Weight gain and feed intake were measured every 2 wk. At weighing, a tail-biting injury score was given to each pig. Blood samples were collected and analyzed for neutrophil:lymphocyte ratio before regrouping at the beginning of the experiment, 24 to 48 h after regrouping, and on the last day of each trial. The use of feeders by individual pigs was assessed by behavioral observations. Average daily gain for the entire 12-wk trial did not differ among group sizes (861, 873, 854, and 845 g/d for groups of 10, 20, 40, and 80, respectively; P > 0.10). During the first 2 wk, ADG was lower for pigs in groups of 40 (554 g/d) than pigs in groups of 10 (632 g/d; P < 0.05), but not pigs in groups of 20 or 80 (602 and 605 g/d, respectively). Average daily feed intake, feed efficiency, and variability in final BW within a pen also did not differ among group sizes. Tail-biting injury scores increased throughout the study, but did not differ among group sizes. Similar proportions of pigs were removed from the trial for health reasons, primarily due to tail biting, in all treatments. Individual pigs in each group size ate from most, if not all, of the feeders in the pen. There was no evidence of spatial subgrouping within the larger groups. The results suggest that housing growing-finishing pigs in groups of up to 80 pigs is not detrimental to productivity and health if space allowance is adequate and feed resources are evenly distributed.     

Interaction of swine nursery and grow-finish space allocations on performance

Two experiments were conducted to evaluate the possible interaction of nursery space allocations and grow-finish space allocations in swine. In Exp. 1, crowding was achieved by varying the number of pigs per pen. During the nursery phase, decreasing the space allocation (0.16 m2/pig vs 0.25 m2/pig; 8 and 12 pens per treatment, respectively) by increasing the number of pigs per pen (18 vs 12) resulted in a decrease in daily feed intake (0.609 vs 0.683 kg/d; P < 0.001) and daily gain (0.364 vs 0.408 kg/d; P < 0.001). Pigs were mixed within nursery treatment groups and reassigned to grow-finish pens (6 pens per treatment) at the end of the 35-d nursery period providing either 0.56 m2/pig (14 pigs/pen) or 0.78 m2/pig (10 pigs/pen). Crowding during the grow-finish phase decreased daily feed intake (P < 0.003) and daily gain (P < 0.001). In Exp. 2, space allocations of 0.16 m2/pig vs 0.23 m2/pig during the nursery phase (24 pens per treatment) resulted in a decrease in daily feed intake (0.612 vs 0.654 kg/d; P < 0.005) and daily gain (0.403 vs 0.430 kg/d; P < 0.001). Pigs remained in the same (social) groups when moved to the grow-finish phase. Unlike Exp. 1, there was no effect of crowding during the grow-finish phase (0.60 m2/pig vs 0. 74 m2/pig) on daily feed intake or daily gain. The difference in results between experiments suggests that the response to crowding during the grow-finish phase may depend in part on whether pigs are mixed and sorted following movement from the nursery.     

Feeder location did not affect performance of weanling pigs in large groups

Crossbred pigs weaned at 17 d of age (n = 1,760; mean initial BW = 5.6 +/- 0.7 kg) were used in two 4-wk trials (four replicates per trial) to evaluate the effects of three pen designs on pig performance. The designs were 1) large group size (100 pigs/pen) with five two-sided feeders in a single, central location in the pen; 2) large group size (100 pigs/pen) with five two-sided feeders in multiple (five) locations in the pen; and 3) small group size (20 pigs/pen) with a single two-sided feeder in a central location in the pen. Each feeder provided two 20.3-cm-wide feeding places on each side. Pigs had free access to feed and water. Feeder-trough space (4 cm/pig) and floor-area allowance (0.17 m2/pig) were the same for all treatments. Pigs in the large-group treatments were lighter (15.6 and 15.6 vs 16.0 kg; P < 0.01) at the end of wk 4 and had lower ADG (358 and 357 vs 373 g; P < 0.01) and ADFI (510 and 521 vs 544 g; P < 0.01) during wk 2 through 4 than pigs in small groups. Gain:feed ratio was similar (P > 0.05) for all treatment groups throughout the study. For large groups, feed disappearance from each of the five feeders was similar (P > 0.05) for both multiple- and single-location treatments. In summary, large group size reduced pig growth performance, but the approach to providing multiple feeding locations that was employed in this experiment did not increase feed intake or growth performance of pigs in the large groups.     

Group size and floor-space allowance can affect weanling-pig performance

Crossbred weanling piglets (n = 1,920; mean initial BW, 5.3 +/- .7 kg) were used in two 9-wk trials employing a randomized block design in a 2 x 2 factorial arrangement of treatments to determine effects of group size (20 [Small = S] or 100 [Large = L] pigs/pen) and floor-space allowance (calculated requirement [CR] or calculated requirement less 50% of estimated "free space" [CR-50]) on growth performance. Free space was estimated for each group size. From wk 1 through 4 after weaning, S and L groups at CR were allowed a floor space of .17 m2/pig, and at CR-50, S and L groups were allowed .15 m2/pig and .13 m2/pig, respectively. From wk 5 through 9 after weaning, all CR treatment pigs were provided a floor space of .38 m2/pig, and for the CR-50 treatment, S and L pigs were allowed .32 m2/pig and .28 m2/pig, respectively. Piglets had free access to feed and water. Feeder-trough space per pig was the same for both group sizes. Feed-intake data were collected for only wk 1 through 4. Group size by floor-space allowance interactions (P < .05) were found for gain/feed ratio (G/F) for wk 1 and wk 2 through 4, but not for wk 1 through 4. Piglets in L groups were lighter (P < .001) at the end of wk 1, 4, and 9 by 2, 4, and 5%, respectively, and had lower ADG (6%; P < .001) throughout the trial than S piglets. During wk 1 through 4, feed intake was lower (7%, P < .001) in L piglets than in S piglets, but G/F was similar (P > .05). Piglets in CR groups had greater ADG (5%; P < .01) throughout the trial, with a greater G/F (P < .05) for wk 1 through 4, and were heavier (P < .01) than those in CR-50 groups at the end of wk 4 (3%) and 9 (4%). Pigs in L groups had a greater within-pen coefficient of variation in BW at the end of wk 9 than pigs in S groups. Large groups and reduced floor-space allowance reduced piglet growth performance in the nursery.     

Responses of weanling pigs to dietary supplementation with vitamin C or carbadox

A 2 X 2 factorial arrangement with two levels (0, 660 ppm) of vitamin C and two levels (0, 55 ppm) of carbadox supplementation was used in two experiments with 112 crossbred pigs weaned between 4 and 5 wk of age. An 18% protein corn-soybean meal-oats-dried whey starter diet was used as the basal diet. Each diet was fed ad libitum for a 4-wk period to three replicates of four pigs in Exp. 1 and to four replicates of four pigs in Exp. 2. Vitamin C supplementation produced a significantly higher plasma vitamin C concentration in weanling pigs, but, contrary to results of our previous study, failed to improve average daily gain of the pigs. Daily gain was, however, improved significantly by carbadox supplementation. Carbadox also produced a significantly higher plasma vitamin C concentration in pigs after a 7-d lag period. Plasma Fe concentration of pigs was not affected by supplemental vitamin C, but was significantly higher in those fed carbadox-supplemented diets. Plasma ceruloplasmin concentration increased significantly in all treatment groups from the initial sampling period (d 0) to subsequent periods. No interactions between supplemental vitamin C and carbadox were observed in daily gain, feed efficiency and the measured plasma constituents.     

Effects of diet and housing density on growth and stomach morphology in pigs.

Two experiments were conducted to evaluate the impact of housing density on the stomach morphology of growing pigs and determine whether there was an interaction between housing density and diet. All diets were corn-soybean meal based. In Exp. 1, 42 barrows (41.0+/-.95 kg BW) were allotted either individually or three pigs per pen to evaluate the effects of crowding on stomach lesions. Pen space per pig was 1.54 and .51 m2, respectively. All pigs were fed a finely ground and pelleted diet (610 microm) for 6 wk. The ADG decreased (P<.05) for the pigs housed three per pen during wk 4 to 6 only. There was no effect of housing density on feed intake or gain/feed ratio. Neither visual nor histological ulcer score differed between the two treatment groups. No stomachs were graded as normal. In Exp. 2, 80 barrows (39.8+/-.9 kg BW) were allotted either two or four pigs per pen. Pen space per pig was .77 and .39 m2, respectively. Half of the pigs in each housing situation were fed a coarse meal diet (1,050 microm), and half of the pigs were fed a finely ground and pelleted diet (577 microm) throughout the 49-d experimental period. Throughout the trial, pigs housed two per pen gained at a greater rate (P<.05) than pigs housed four per pen. From d 14 to the end of the trial, pigs consuming the finely ground and pelleted diet gained at a greater rate (P<.05) than pigs fed the coarse meal diet. The differences in ADG were reflected in final body weight. Stomach weight as a percentage of body weight was higher for animals on the coarse meal diet. Visual and histological ulcer scores were similar, and both were higher (P<.001) on the finely ground and pelleted diet, indicating greater damage. There was no effect of space restriction on stomach morphology. These data show the major effect of diet type on stomach lesions with no interaction with space restriction.     

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.     

Brewers dried yeast as a source of mannan oligosaccharides for weanling pigs

Brewers dried yeast, a source of mannan oligosaccharides (MOS), was assessed as an alternative to an antimicrobial agent (carbadox) for young pigs in two experiments. The yeast contained 5.2% MOS. Agglutination tests confirmed adsorption of several serovars of E. coli and Salmonella spp. onto the yeast product. In Exp. 1, seven replicates (five pigs per pen) of 22-d-old pigs were fed a nonmedicated basal diet or the basal diet with carbadox (55 mg/kg), yeast (3%), or a combination of 3% yeast and 2% citric acid for 28 d. Carbadox did not improve growth performance. Growth rate and feed intake were depressed (P < 0.05) in pigs fed yeast alone or in combination with acid. Log counts of total coliforms, Escherichia coli, and Clostridium perfringens in feces were not affected by diet, but Bifidobacteria spp. counts were lower (P < 0.05) in pigs fed the yeast + acid diet and lactobacilli counts were higher (P < 0.05) in pigs fed yeast. Fecal pH and VFA concentrations and intestinal morphological traits were not consistently affected by diet. Serum IgG levels were elevated in the yeast + acid (P < 0.01) group. In Exp. 2, the effects of yeast and carbadox additions to the diet on enteric microbial populations in young pigs housed in isolation units were evaluated. Pigs (n = 24) were weaned at 11 d of age (4.1 kg BW) and placed in isolation chambers (two pigs per chamber) equipped with individual air filtering systems and excrement containers. Treatments were a nonmedicated basal diet and the basal diet with 55 mg/kg of carbadox or with 3% yeast. Diets were fed for 29 d, then each pig was orally dosed with approximately 9.5 x 10(8) CFU of E. coli K88. Daily fecal E. coli K88 counts were not different (P > 0.05) among treatments, but fecal shedding of carbadox-resistant coliforms was higher (P < 0.01) during the 9-d period in pigs fed carbadox. Total fecal coliforms were consistently lower throughout the postinoculation period in pigs fed yeast (P < 0.05). Yeast reduced colonization oftotal coliforms in the duodenum,jejunum, cecum, and colon, but it did not have a consistent effect on colonization of E. coli K88. Pigs fed yeast tended (P < 0.10) to have higher serum IgG levels than controls. In these experiments, brewers dried yeast and carbadox had minimal effects on growth, microbial populations, and intestinal health traits of early-weaned pigs, but certain serum immunological traits were enhanced by feeding yeast.     

Effects of restricted feed intake on finishing pigs weighing between 68 and 114 kilograms fed twice or 6 times daily

In a previous study with limit-fed gestating gilts, we observed that gilts fed 6 times/d had greater ADG than those fed the same amount over 2 feedings. To confirm these earlier responses, we used finishing pigs as a model in two 42-d trials and two 28-d trials to evaluate the effects of restricted feed intake and feeding frequency (2 vs. 6 times/d, floor fed) on pig performance between 68 and 114 kg. In all experiments, pigs (10/pen) were housed in 1.8 × 3.1 m pens with a half-solid, half-slatted concrete floor. Pigs were fed a corn- and soybean meal-based diet formulated to 1.15% standardized ileal digestible Lys and 3,294 kcal of ME/kg. In Exp. 1 to 3, energy and Lys were supplied to pigs according to NRC (1998) calculations to target an ADG of 0.80 kg. In Exp. 4, the diet was supplied to pigs to target an ADG of 0.80 kg (low feed intake) or 0.95 kg (high feed intake) to determine if the amount of energy above the maintenance requirement and feeding frequency affected pig performance. Pigs were fed by dropping similar amounts of feed onto the solid concrete floor either 2 (0700 or 1400 h) or 6 times (3 meals within 2 h at the morning and afternoon feedings) per day with an Accu-Drop Feed Dispenser (AP Systems, Assumption, IL). In Exp. 1 and 2, pigs fed 6 times daily had increased (P < 0.02) ADG and G:F compared with pigs fed 2 times per day. Greater feeding frequency increased (P < 0.05) the duration of time spent feeding and standing and reduced the lying time. In Exp. 3, a third treatment was included to determine whether the improvements in performance were due to decreased feed wastage. This treatment was designed to minimize feed wastage by dropping feed closer to the floor for pigs fed 2 times per day. Pigs fed 6 times daily had improved (P < 0.05) ADG and G:F compared with pigs in either treatment fed 2 times per day. No difference (P > 0.05) in performance was observed between pigs fed 2 times per day when feed was dropped from the feed drop or by the modified method. In Exp. 4, increasing the feeding frequency from 2 to 6 times per day improved (P < 0.01) ADG and G:F for pigs fed the low feed intake and tended to increase (P < 0.06) ADG and improved (P < 0.05) G:F for pigs fed the high feed intake. In limit-feeding situations, increasing the frequency of feeding from 2 to 6 times per day improved pig performance, which confirmed our earlier findings in gestating gilts.     

Effect of group size and feeder type on growth performance and feeding patterns in growing 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 growing pigs over a 4-wk period. A total of 416 hybrid pigs (barrows and gilts) were grown from 26.5 (SD = 1.6) to 47.8 (SD = 2.7) kg BW and given ad libitum access to a corn-soybean meal-based diet (17.4% CP; 0.9% lysine; 3,298 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Pigs using the electronic feeders had similar growth rates but lower feed intakes (P < 0.01) and higher gain:feed ratios (P < 0.01) compared to those using the conventional feeders. Barrows compared to gilts had higher growth rates (P < 0.05), numerically higher (P > 0.05) ADFI, and similar feed efficiency and feeding pattern. Feed intakes and growth rates were lowest (P < 0.05) for groups of 12 pigs but gain:feed ratio was not affected by group size. Daily feeder occupation time per pig was lower (P < 0.01) for groups of 12 than for groups of 2 or 4 pigs, and feed consumption rate was higher (P < 0.01) for groups of 12 than for groups of 4 pigs. The proportion of time spent eating was lower (P < 0.01) and the proportion of time spent standing was higher (P < 0.01) for pigs in groups of 12 compared to groups of 2. Correlations between ADG and ADFI and feed intake per visit were 0.29 and 0.30, respectively (P < 0.01), between ADG and ADFI and feed consumption rate were 0.27 and 0.31, respectively (P < 0.01), and between ADFI and feeder occupation time per day were 0.33 (P < 0.01). This study suggests that, in growing pigs given access to a single feeder, changes in feeding behavior with increasing group size were not sufficient to maintain feed intake and growth rate.     

Effect of neomycin, carbadox and length of adaptation to calorimeter on performance, fasting metabolism and gastrointestinal tract of young pigs

Five sets of littermate gilts (8.2 +/- .19 kg average initial weight) were randomly assigned within litter to a 16% protein corn-soybean meal basal diet (B), B + .308% neomycin, or B + 55 ppm carbadox. Each set was equally-fed individually once daily for 16 d in metabolism cages and 5 d in calorimeters. The average daily feed intake for 21 d was 276 g. Oxygen consumption and CO2 production were measured during an 8- to 24-h postprandial period on d 16, 19, 20 and 21, and during a 32- to 48-h postprandial period after the d 21 feeding. Pigs were killed 50 h postprandially for gastrointestinal tract measurements. Dietary supplementation of antimicrobial agents (neomycin and carbadox) resulted in improvements (P less than .01) in daily gain and efficiency of feed utilization and lower (P less than .05) small intestinal mass in pigs. There was no difference (P greater than .05) in daily gain, feed efficiency or small intestinal mass between pigs fed neomycin- or carbadox-supplemented diets. Whole-animal fasting O2 consumption and CO2 production measured during the 8- to 24-h or 32- to 48-h postprandial period were not affected (P greater than .05) by the supplementation or the source of dietary antimicrobial agents. There were no differences (P greater than .05) in 8- to 24-h fasting O2 and CO2 measurements determined on d 16, 19, 20 and 21, indicating that adaptation to calorimeters was not needed by the pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of carbadox on net absorption of ammonia and glucose into hepatic portal vein of growing pigs

Chronic cannulas were placed into the hepatic portal vein, ileal vein and carotid artery of growing pigs trained to consume their daily allowance of 1.2 kg of feed (16% protein corn-soybean meal basal diet) in a single meal. The average preoperative BW of pigs was 44.7 kg for Trial 1 (three pigs) and 35.3 kg for Trial 2 (seven pigs). In Trial 1, net absorption of ammonia (NH3) and glucose into the portal vein was determined three times at weekly intervals. The net portal absorptions were derived by multiplying the porto-arterial plasma concentration difference of NH3 and glucose by portal vein plasma flow rate estimated with the p-aminohippuric acid indicator-dilution technique. Differences in the net portal absorptions of NH3 and glucose among the three weekly measurements were small (P greater than .05). In Trial 2, the first sequence of net portal absorption measurements was conducted when pigs were fed the basal diet, and the second sequence of measurements was conducted after the pigs had been fed the diet supplemented with 55 ppm of carbadox for 7 d. Carbadox supplementation reduced (P less than .05) plasma NH3 concentration in portal plasma during the 2.5-h to 5-h postprandial period and decreased (P less than .05) net portal absorption of NH3 during the 2.5-h to 4-h postprandial period. Carbadox, however, did not affect (P greater than .05) net portal absorption of glucose. We suggest that carbadox suppresses the production of cell-toxic NH3 by intestinal microorganisms and, thus, reduces the injury and turnover of intestinal cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary fat on pig performance and dust levels in modified-open-front and environmentally regulated confinement buildings

Four trials were conducted with 1,480 pigs (initial wt: 23 kg in trial 1,29 kg in trial 2 and 49 kg in trial 3 and 4) to determine the effect of dietary fat on pig performance, nutrient separation in an automated feed distribution system, dust levels in swine buildings and integrity of the respiratory system of swine. Two modified-open-front (B-1 and B-2) and two environmentally regulated (E-1 and E-2) growing-finishing buildings, of identical design, were used in each trial. In trial 1, 250 pigs (25 pens of 10 pigs/pen) in B-1 were fed a ground, mixed, corn-soybean meal diet (15% crude protein) with added tallow (5%), and 250 pigs in B-2 were fed the same diet but without added tallow. The assignment of diets to buildings were reversed in trial 2 in which 2.5% tallow was used instead of 5%. Each diet was fed ad libitum to pigs, and was distributed by an automated "Flexauger" system in trials 1 and 2. In each of trials 3 and 4, 120 pigs (12 pens of 10 10 pigs/pen) in E-1 were fed a corn-soybean meal diet (14% crude protein) with added tallow (5%) and 120 pigs in E-2 were fed the same diet but without added tallow. Overall, pigs fed the diet with tallow gained faster (P less than .002), consumed less feed (P less than .02) and converted feed more efficiently (P less than .002) than those fed the diet without tallow in trials 1 and 2. Pig performance was also improved by the addition of tallow to the diet in trials 3 and 4 (P less than .002). Crude protein, Ca, P and Cu contents of both diets were similar at each location sampled throughout the automated distribution system in trials 1 and 2. Addition of tallow to the diets reduced aerial dust levels, both with the feed distribution auger running (P less than .002) and without the auger running (P = .06) in trials 1 and 2. In trials 3 and 4, adding 5% tallow to the diet reduced aerial dust concentrations of of particle sizes of 14, 4, and 1.5 micron (P less than .002) and .4 micron (P = .07). The amount of settled dust was lower (P less than .001, trials 1, 3 and 4) when tallow was included in the diet.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Effects of excess arginine on swine growth and plasma amino acid levels

One hundred seventy-six crossbred weaned pigs (4 to 5 wk old) were used in two growth trials to determine the effect of excess arginine on pig growth and plasma amino acid levels. In the first 28-d growth trial, two lysine levels (1.03 and 1.26%) and three arginine levels (.94, 1.29 and 1.63%) were used in a nested treatment arrangement. Lysine supplementation improved daily gains (P less than .05), tended to improve feed efficiency (P less than .12) and caused a general reduction in plasma essential amino acid levels. Arginine had no effect on daily gain or feed intake, but pigs fed 1.03% lysine and 1.63% arginine had reduced gain/feed (P less than .05). Arginine did not affect gain/feed of pigs fed 1.26% lysine. Plasma lysine levels were reduced (P less than .06) by excess arginine in pigs fed 1.26% lysine, but not in pigs fed 1.03% lysine. The four treatments for the second 26-d growth trial consisted of three diets containing .92% lysine and either .72, 1.10 or 1.61% arginine and a positive lysine control (1.10% lysine, .72% arginine). Lysine was the limiting amino acid in the basal diet, but arginine had no effect on daily gain, daily feed intake, gain/feed or plasma lysine levels. Plasma threonine and methionine levels were reduced by excess arginine in both experiments, while the other plasma essential amino acid levels were not affected by dietary arginine. Conclusions are that large excesses of added arginine may affect lysine utilization, but pig performance was affected only when excess arginine was combined with a lysine deficiency. The arginine levels similar to those found in grain-soybean meal swine diets had no effect on pig performance in these experiments.     

The effect of space allocation on barrow and gilt performance

Two experiments were conducted to determine the variation in response to space allocation between barrows and gilts and to examine an alternative allocation regimen for barrows and gilts. Experimental space allocations in both experiments were achieved by varying the number of pigs per pen in a fully slatted facility. In Exp. 1, barrows were given 0.58 and 0.65 m2/pig (nine and eight pigs per pen, respectively) and gilts were given 0.65 and 0.74 m2/pig (eight and seven pigs per pen, respectively). In addition, barrows at 0.58 m2/pig were fed diets formulated for barrows or diets formulated for gilts. Barrows grew 4.8% slower (P = 0.031) and ate 3.1% less feed daily (P = 0.062) at 0.58 vs. 0.65 m2/pig from 22 to 115 kg BW, with no difference in feed conversion, daily lean gain, carcass lean percent, or variation in weight within the pen at time of first pig removal to slaughter. There was no improvement in daily gain, feed intake, feed efficiency, lean gain, or carcass lean percent when gilts were given 0.74 vs. 0.65 m2/pig from 22 to 115 kg BW. There was no difference in performance between the population that consisted of barrows and gilts at 0.65 m2/pig vs. the population of barrows at 0.58 m2/pig and gilts at 0.74 m2/pig. There was no difference in performance by barrows at 0.58 m2/pig when fed either barrow or gilt diets, except for a slight increase (P = 0.078) in within-pen weight variation when the first pig was removed for slaughter for the barrows fed gilt diets. In Exp. 2, barrows and gilts were given 0.58 m2/pig or 0.74 m2/pig (18 vs. 14 pigs per pen) from weaning (mean age 17 d) to slaughter on d 168 postweaning. There were no interactions between space allocation and gender. Daily gain and feed intake were decreased by 2.8% (P = 0.037) and 2.9% (P = 0.084), respectively, with no effect on feed conversion or standardized fat-free lean daily gain for the 0.58 vs. the 0.74 m2/pig treatment, whereas total live weight gain per pen was increased 20.8% (P < 0.001). Results of Exp. 1 suggest that space allocation can be used to achieve similar growth rates between barrows and gilts, and results of Exp. 2 suggest that the response to space allocation is similar for barrows and gilts. The difference in magnitude of response to space allocation between experiments may be due in part to when the social group was formed, with a smaller difference in performance in Exp. 2 associated with a stable social group from weaning to slaughter.     

乳化脂肪粉对断奶仔猪生长性能的影响

试验旨在研究乳化脂肪粉对断奶仔猪生长性能的影响。选择21日龄的断奶仔猪,按体重相近原则随机分栏成为两个对照组(基础日粮)和一个试验组:试验组在基础日粮中添加20 kg/t的乳化脂肪粉,每个处理2个重复(♀和♂各一栏),每个重复15头,试验期为10 d。研究结果表明:试验组和对照组的平均日采食量分别为0.239 kg、0.257 kg和0.240 kg;平均日增重分别为0.144 kg、0.129 kg和0.131 kg;平均料肉比分别为1.66、1.99和1.80。试验组的平均日采食量和平均料肉比均比两个对照组的低,而试验组的平均日增重比两个对照组高。研究结果表明:在本次试验中,乳化脂肪粉可以增加断奶仔猪的日增重、降低料肉比、提高饲料利用率,乳化脂肪粉对断奶仔猪的生长性能可以产生正面影响。     

Effect of dietary protein fluctuations and space allocation on performance and carcass quality of growing-finishing pigs

Two trials with growing-finishing pigs were conducted to evaluate the effects of fluctuating dietary CP levels and/or space allocation on performance and carcass traits. In Trial 1, three CP regimens were used with 216 growing-finishing pigs (mixed sex). Average initial and final weights of pigs were 31 and 103 kg, respectively. The CP regimens consisted of: 1) control (18% CP from wk 0 to 4; 15% CP from wk 4 to 12); 2) moderate CP variations (MCPV = 19.5% CP from wk 0 to 2, 16.5% CP from wk 2 to 6, 13.5% CP from wk 6 to 8, 16.5% CP from wk 8 to 10, 13.5% CP from wk 10 to 12); and 3) extreme CP variations (ECPV = 21% CP from wk 0 to 2, 15% CP from wk 2 to 4, 18% CP from wk 4 to 6, 12% CP from wk 6 to 8, 18% CP from wk 8 to 10, 12% CP from wk 10 to 12). Overall (wk 0 to 12), treatment differences were not observed (P > 0.05) for gain, feed intake, CP intake, gain:feed ratio, or gain/CP intake. Trial 2 involved 360 finishing pigs (mixed sex) in a 3 x 2 factorial arrangement (three dietary CP regimens, two floor space allowances). The diets consisted of: 1) control (16% CP from wk 0 to 4, 15% CP from wk 4 to 8; 14% CP from wk 8 to 12); 2) MCPV (17.5% CP from wk 0 to 2, 14.5% CP from wk 2 to 4, 16.5% CP from wk 4 to 6, 13.5% CP from wk 6 to 8, 15.5% CP from wk 8 to 10, 12.5% CP from wk 10 to 12); and 3) ECPV (19% CP from wk 0 to 2, 13% CP from wk 2 to 4, 18% CP from wk 4 to 6, 12% CP from wk 6 to 8, 17% CP from wk 8 to 10 wk, 11% CP from wk 10 to 12). Pigs were provided with either 1.12 m2 (uncrowded; five pigs/pen) or 0.56 m2 (crowded; 10 pigs/pen). Average initial weight was 49 kg and final weights were 126 kg (uncrowded) and 118 kg (crowded). Overall (0 to 12 wk), crowded pigs had lower (P < 0.05) ADG (822 vs. 916 g) and feed (as-fed) intakes (2,633 vs. 2,876 g) than uncrowded pigs. At the end of the 12-wk trial, a control vs. ECPV x space interaction (P < 0.05) occurred for weight gain, fat depth, and percentage of lean. Thus, uncrowded pigs fed ECPV gained faster (933 vs. 887 g) but had a lower percentage of lean (53.5 vs. 54.5) than controls, whereas crowded pigs on the ECPV regimen gained more slowly (812 vs. 842 g) but were leaner (54.8 vs. 54.6%) than those on the control CP regimen. Despite the wide dietary CP fluctuations, pigs in both trials consumed about the same quantity of CP during the 12-wk feeding periods. These data suggest that uncrowded pigs respond differently than crowded pigs to fluctuating levels of dietary CP.     

Lack of influence of nursery temperature on the response of weanling pigs to supplemental vitamins C and E

Three trials using 240 weanling pigs were conducted during winter months to determine the influence of nursery temperature ("comfortable" vs "cold") on the response of weanling pigs to added vitamin C (700 ppm) or E (55 IU/kg) to a corn-soybean meal diet. A "comfortable" temperature schedule (27 C initially with a weekly 2 C drop) was maintained in one nursery, with the temperature schedule in the "cold" nursery about 8 C lower. Plasma concentrations of vitamin C and vitamin E were elevated when the respective vitamins were added to the diet, but were not consistently influenced by nursery temperatures. Daily gain, daily feed intake and feed efficiency were not improved with the added C or E. Daily feed intake was increased and feed-to-gain ratios were larger for pigs housed in the "cold" nursery compared with pigs housed in the "comfortable" nursery; however, daily gains were similar in the two environments. Pigs housed in the "cold" nursery were slightly stressed, as indicated by heavier adrenal glands, but the antibody response and serum glucocorticoid concentrations were not significantly affected by either diet or temperature.