The interrelationship between crude protein and exogenous porcine somatotropin on growth, feed and carcass measurements of pigs

In three experiments the interrelationship between dietary CP and recombinant porcine somatotropin (rpSt, i.m. daily) on ADG, feed efficiency (F/G) and carcass traits was examined in crossbred Yorkshire gilts and barrows given ad libitum access to their diets during the finishing period (55 to 110 kg BW). Pigs, blocked by BW and gender, were assigned (four/pen) within block. In Exp. 1, 140 pigs were assigned two/gender per pen to each of five pens/block and received a diet of either 12%, 18% or 24% CP (n = 2, 1 and 2 pens/block, respectively). Pigs received rpSt, either 0 or 120 micrograms/kg BW (12% and 24% CP groups) or 60 micrograms/kg BW (18% CP group). When CP was 12%, rpSt decreased ADG and increased F/G (P less than .05), whereas when CP was 18% or 24%, rpSt increased ADG and lowered F/G (P less than .05). Backfat thickness was reduced (P less than .05) by rpSt regardless of CP. In Exp. 2, 120 pigs were assigned two/gender per pen to each of five pens/block and received a diet of 24% CP. Either 0, 15, 30, 60 or 120 micrograms of rpSt/kg BW was administered to each pig. All doses of rpSt increased ADG, lowered F/G and decreased backfat thickness compared with measurements for control pigs (P less than .05). In Exp. 3, 140 pigs were assigned two/gender per pen to each of seven pens/block and received a diet of either 14%, 18% or 24% CP (n = 3, 2 and 2 pens/block, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of feeder-trough space and variation in body weight within a pen of pigs on performance in a wean-to-finish production system

Two studies were carried out with the same group of pigs within a wean-to-finish system. In Study 1 (weaning to wk 8 postweaning), the effect of feeder-trough space in pens that were double-stocked on pig growth was evaluated. In Study 2 (end of wk 8 to 112 +/- 1.5 kg BW), the effect of variation in pig BW within a pen on growth was investigated. In Study 1, a randomized block design was used to compare two feeder-trough space treatments (Double [4 cm/pig] vs Control [2 cm/pig]). Pigs (n = 1,728) were randomly allocated at weaning (5.4 +/- 0.01 kg BW; 16 d of age) to mixed-sex pens (8 pens/treatment) of 108 pigs/pen on the basis of BW. Floor-space (0.30 m2/pig) and drinker allocation (13 pigs/drinker) were the same for both treatments. Two six-place (35 cm/place) feeders were positioned together in the center of each pen and were accessible from both sides. For the Double treatment, both feeders contained feed, whereas for the Control only one feeder contained feed. In Study 2, a randomized block design was used to compare three BW/variation in BW treatments: 1) Heavy BW/Low variation, 2) Light BW/Low variation, and 3) Mixed BW/Normal variation. The double-stocked pens of pigs from within previous feeder-trough space treatment were split into two groups of 54 pigs (equal sex ratio) having either high or low BW variation within pen. Pigs had free access to feed and water throughout the studies. In Study 1, doubling feeder-trough space did not affect (P > 0.05) pig growth from weaning to the end of wk 6. From wk 6 to 8, pigs on the Double treatment compared to the Control treatment had higher (P < 0.05) ADG and were heavier (P < 0.05), but had similar (P > 0.05) ADFI and gain:feed ratio. In Study 2, pen-BW treatment did not impact (P > 0.05) ADG or gain:feed ratio; however, Heavy/Low had greater (P < 0.01) ADFI than Light/Low with Mixed/Normal being intermediate for ADFI. At 112 kg BW, CV of BW within a pen was similar (P > 0.05) across treatments; however, days to market BW was greater (P < 0.001) for Light/Low than Heavy/ Low with Mixed/Normal being intermediate. In summary, increasing feeder-trough space from 2 to 4 cm per pig increased daily gain after wk 6 postweaning in double-stocked pens of pigs; however, sorting pigs on the basis of BW when splitting pens did not impact growth rate or variation in BW within a pen at market BW.     

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 removal and remixing of lightweight pigs on performance to slaughter weights

Two experiments were conducted to determine the effect of lightweight pig removal and remixing on performance to slaughter. Experiment 1 was a growing-finishing trial utilizing a total of 900 pigs (26.2+/-0.1 kg initial weight) that were sorted and remixed at a mean replicate BW of 72 kg. Experiment 2 was a wean-to-finish trial (17 d mean wean age; 4.8 kg +/- 0.1 BW) utilizing 225 barrows with sorting and remixing occurring 3 wk after weaning. Treatments were 15 pigs/ pen from initial weight to slaughter (15S), 20 pigs/pen from initial weight to time of sort and remix and then reduced to 15 pigs/pen (20/15), and 15 pigs/pen from time of sort and remix to slaughter comprised of the five lightest pigs from each of three 20/15 pens per replicate (15M). Space allocation was 0.56 m2/pig from 26 to 70 kg and 0.74 m2/pig thereafter in Exp. 1. In Exp. 2, pen size was fixed at 2.44 x 4.27 m. In Exp. 1, there was no effect (P > 0.20) of treatment on performance prior to 70 kg. Least squares means for ADG from time of sort and remix to first pig removal from a pen for slaughter at 113 kg were 0.93, 0.87, and 0.91 kg/d for the 20/15, 15M, and 15S treatments, respectively (P < 0.05). When comparing the population represented by the 20/15 + 15M treatments vs the 15S population, there was no difference (P > 0.20) in ADG, ADFI, feed conversion, or carcass lean content. In Exp. 2, pigs in the 20/15 treatment grew slower (P < 0.05) than 15S pigs for the first 21 d (0.20 vs 0.22 kg/d, respectively) with a lower ADFI (P = 0.06) and no difference in feed conversion. When comparing the population represented by the 20/15 + 15M treatments vs the 15S population after sorting and remixing, there was no effect (P > 0.15) of experimental treatments on ADG, ADFI, feed conversion efficiency, carcass lean content, or daily lean gain. These results suggest that removal of lightweight pigs and remixing of the removed pigs into pens of similar-weight pigs is ineffective in improving the overall performance of a population of pigs during the postweaning period.     

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 increasing dietary L-carnitine on growth performance of weanling pigs

Four experiments were conducted to evaluate the effects of supplementing graded levels (0 to 100 ppm) of L-carnitine to the diet of weanling pigs on growth performance during a 34- to 38-d experimental period. A fifth experiment was conducted to determine the effects of addition of L-carnitine to diets with or without added soybean oil (SBO) on growth performance. In Exp. 1, 128 pigs (initial BW = 5.5 kg) were allotted to four dietary treatments (six pens per treatment of four to six pigs per pen). Dietary treatments were a control diet containing no added L-carnitine and the control diet with 25, 50, or 100 ppm of added L-carnitine. In Exp. 2, 3, and 4, pigs (4.8 to 5.6 kg of BW) were allotted to five dietary treatments consisting of either a control diet containing no added L-carnitine or the control diet with 25, 50, 75, or 100 ppm of added L-carnitine. All diets in Exp. 1 to 4 contained added soybean oil (4 to 6%). There were seven pens per treatment (four to five pigs per pen) in Exp. 2, whereas Exp. 3 and 4 had five and six pens/treatment (eight pigs per pen), respectively. In general, dietary carnitine additions had only minor effects on growth performance during Phases 1 and 3; however, dietary L-carnitine increased (linear [Exp. 1], quadratic [Exp. 2 to 4], P < 0.03) ADG and gain:feed (G:F) during Phase 2. The improvements in growth performance during Phase 2 were of great enough magnitude that carnitine addition tended to increase ADG (linear, P < 0.10) and improve G:F (quadratic, P < 0.02) for the entire 38-d period. In Exp. 5, 216 weanling pigs (5.8 kg of BW) were allotted (12 pens/treatment of four to five pigs per pen) to four dietary treatments. The four dietary treatments were arranged in a 2 x 2 factorial with main effects of added SBO (0 or 5%) and added L-carnitine (0 or 50 ppm). Pigs fed SBO tended (P < 0.07) to grow more slowly and consumed less feed compared with those not fed SBO, but G:F was improved (P < 0.02). The addition of L-carnitine did not affect (P > 0.10) ADG or ADFI; however, it improved (P < 0.03) G:F. Also, the increase in G:F associated with L-carnitine tended to be more pronounced for pigs fed SBO than those not fed SBO (carnitine x SBO, P < 0.10). These results suggest that the addition of 50 to 100 ppm of added L-carnitine to the diet improved growth performance of weanling pigs. In addition, supplemental L-carnitine tended to be more effective when SBO was provided in the diet.     

Growing-finishing performance and carcass characteristics of pigs fed normal and genetically modified low-phytate corn

A genetically modified corn hybrid homozygous for the lpa1 allele, containing low phytate (LP), and its nearly isogenic equivalent hybrid (normal) were compared in two experiments with growing-finishing swine. In Exp. 1, 210 barrows (27 kg) were allotted to one of six dietary treatments with two corn hybrids (LP and normal) and three P feeding regimens. There were five replicate pens (seven pigs/pen) per treatment. Treatments consisted of diets that were supplemented with P throughout the growing-finishing period (.2% P and .15% supplemental P during growing and finishing phases, respectively) or only during the growing phase (.2% supplemental P) or that were not supplemented with P throughout the growing-finishing period. Performance at the end of the growing phase was based on a 2 x 2 factorial arrangement of treatments with two corn hybrids and two levels of added P (0 and .2%). This resulted in 10 replicates for the treatments supplemented with .2% P. The finishing phase (73 to 112 kg) was a 2 x 3 factorial arrangement of treatments with the two types of corn and three regimens of added P during the finishing period. Breaking load (BL) and ash of the fourth metacarpal were evaluated from one pig/pen at the end of the growing phase and from all pigs after slaughter. Pigs fed the LP corn diet without added P had greater body weight gain, feed efficiency, BL, and ash content of the fourth metacarpal than pigs fed the normal corn diet without added P. Performance was similar between pigs fed the LP diet without added P and pigs fed LP and normal corn with added P. In Exp. 2, 1,092 gilts (34 kg body weight) were allotted by weight in a commercial facility to one of three treatments: 1) normal corn/soybean meal diet containing .29% and .22% available P during the growing and finishing phases, respectively; 2) LP corn/soybean meal diet with the same available P level as Treatment 1; and 3) same as Treatment 2 for 8 wk, then no inorganic P supplementation during the finishing phase. All pigs were slaughtered at approximately 122 kg. There were no significant differences in growing-finishing performance or BL among treatments. However, pigs fed diets containing LP corn possessed carcasses with less backfat and a higher percentage of lean (P < .01). These results confirm that the P in LP corn is available to the pig and suggest that pigs fed diets containing this genetically modified corn will have more desirable carcasses.     

The effects of R-salbutamol on behavior and physiology of finishing pigs

Salbutamol has potential for use as a repartioning agent in swine. The aims of this experiment were to determine effects of salbutamol on behavior and physiology of finishing pigs. The study used 192 pigs (88.8 +/- 0.9 kg of BW) housed in groups of 6 in 32 pens and assigned to 1 of 4 treatments: 1) control-0 mg/kg of salbutamol, 2) 2R--control diet with 2 mg/kg of the pure R-enantiomer of salbutamol, 3) 4R--control diet with 4 mg/kg of pure R-salbutamol, or 4) 8RS--control diet with 8 mg/kg of a 50:50 mixture of the R- and S-enantiomers. All diets were offered ad libitum for 4 wk. Salbutamol diets were replaced with control diets 24 to 48 h before slaughter. Behavioral responses to handling during weighing were recorded immediately before assignment to the treatments (wk 0) and at weekly intervals over the next 4-wk period. Behavioral and heart rate (HR) responses to a 10-min human presence test in the home pen were measured during wk 0, wk 1, and wk 3. Heart rate responses to a 36-min transportation were recorded. One pig from each pen had blood collected 4 times: during wk 0, 2, 4, and at exsanguination. Blood was analyzed for NEFA, creatine kinase, glucose, lactate, blood urea nitrogen, ammonia, insulin, cortisol, norepinephrine, and epinephrine. Data were analyzed using PROC GLM of SAS, with pen as the experimental unit. Treatment had no effect on time spent lying laterally, overall activity, or time spent alert. Treatment had no effect on handling measures (P > 0.05) or on behavioral responses to human presence (P > 0.05), with all pigs willing to spend similar amounts of time close to and touching the human. However, during the human presence test in wk 1 and wk 3, control pigs had HR around 10 peats per minute less (P < 0.05) than pigs in the other 3 treatments. During transport, overall HR were similar across treatments (P > 0.05). However, at certain 1-min time points, control pigs had greater HR than salbutamol-treated pigs (P < 0.05). There were no treatment differences in lactate, epinephrine, or norepinephrine concentrations at any point. During wk 4, control pigs had less creatine kinase (P < 0.02) and greater blood urea nitrogen (P < 0.005) compared with pigs fed all the salbutamol treatments. The home pen behavior, handling, human presence test, and transport results indicate that salbutamol-treated pigs do not show marked differences in home pen time budgets and behavioral and HR responses to handling and transportation compared with control pigs. Thus, salbutamol did not have a negative effect on finishing pig well-being during this study.     

Pre- and postweaning performance of pigs injected with dexamethasone at birth

A trial was conducted to determine pre- and postweaning performance of pigs injected with dexamethasone either 1 or 24 h after birth. In Exp. 1, 225 pigs (Triumph4 x PIC Camborough 22) were assigned according to birth weight and sex to three treatments. Treatments included either saline (Control), Dex1 (2 mg/kg BW i.m. injection of dexamethasone within 1 h of birth), or Dex24 (2 mg/kg BW i.m. injection of dexamethasone within 24 h after birth). Birth weights (1.56 +/- 0.06 kg) did not differ among treatments (P > 0.10) or between sexes (P > 0.10). There was a treatment x sex interaction on BW at weaning (15 d; P < 0.05) with Dex1 and Dex24 males 10% heavier than Control males (4.77 and 4.78 vs. 4.34 kg, respectively), and no significant differences in BW among the females (P > 0.05). In Exp. 2, 180 pigs from Exp. 1 were transported to a segregated early weaning nursery facility where each sex was assigned to 10 pens per treatment (60 pens total). Pigs were fed fortified corn-soybean meal diets in a three-phase feeding program. At the end of Exp. 2 (49-d period), there was a treatment x sex interaction (P < 0.01) for BW with Dex1 and Dex24 barrows being on average 8% heavier than the Control barrows (30.1 and 29.8 vs. 27.7 kg, respectively), and no significant difference in BW (P > 0.10) among the gilts. No treatment differences in feed efficiency (gain:feed) were observed during the nursery period (P > 0.10). In Exp. 3, pigs from the nursery were moved to a finishing facility where each sex was assigned to 4 pens per treatment (24 pens total). All pigs were fed fortified corn-soybean meal diets in a four-phase feeding program with sexes fed separately. Real-time ultrasound was used to measure 10th rib backfat depth and longissimus muscle area. At the end of Exp. 3 (83-d period), there was a treatment x sex interaction (P < 0.05) for final BW with Dex1 and Dex24 barrows being on average 5.45 kg heavier than Control barrows (119.6 and 120.7 vs. 114.4 kg, respectively), and no difference (P > 0.05) in BW among the gilts. No treatment differences (P > 0.10) were observed for backfat depth, longissimus muscle area or gain:feed. These studies demonstrate that dexamethasone (2 mg/kg BW) given within 24 h of birth significantly improves both pre- and postweaning performance of barrows with no beneficial effects on gilts.     

Additivity of effects from dietary copper and zinc on growth performance and fecal microbiota of pigs after weaning

Four experiments were conducted to determine the interactive effects of pharmacological amounts of Zn from ZnO and Cu from organic (Cu-AA complex; Cu-AA) or inorganic (CuSO(4)) sources on growth performance of weanling pigs. The Cu was fed for 4 (Exp. 1) or 6 (Exp. 2, 3, and 4) wk after weaning, and Zn was fed for 4 (Exp. 1) or 2 (Exp. 2, 3, and 4) wk after weaning. Treatments were replicated with 7 pens of 5 or 6 pigs per pen (19.0 ± 1.4 d of age and 5.8 ± 0.4 kg of BW, Exp. 1), 12 pens of 21 pigs per pen (about 21 d of age and 5.3 kg of BW, Exp. 2), 5 pens of 4 pigs per pen (20.3 ± 0.5 d of age and 7.0 ± 0.5 kg of BW, Exp. 3), and 16 pens of 21 pigs per pen (about 21 d of age and 5.7 kg of BW, Exp. 4). In Exp. 1 and 2, Cu-AA (0 vs. 100 mg/kg of Cu) and ZnO (0 vs. 3,000 mg/kg of Zn) were used in a 2 × 2 factorial arrangement. Only Exp. 1 used in-feed antibiotic (165 mg of oxytetracycline and 116 mg of neomycin per kilogram feed), and Exp. 2 was conducted at a commercial farm. In Exp. 3, sources of Cu (none; CuSO(4) at 250 mg/kg of Cu; and Cu-AA at 100 mg/kg of Cu) and ZnO (0 vs. 3,000 mg/kg of Zn) were used in a 3 × 2 factorial arrangement. In Exp. 4, treatments were no additional Cu, CuSO(4) at 315 mg/kg of Cu, or Cu-AA at 100 mg/kg of Cu to a diet supplemented with 3,000 mg/kg of Zn from ZnO and in-feed antibiotic (55 mg of carbadox per kilogram of feed). In Exp. 1 and 2, both Zn and Cu-AA improved (P < 0.001 to P = 0.03) ADG and ADFI. No interactions were observed, except in wk 1 of Exp. 2, where Zn increased the G:F only in the absence of Cu-AA (Cu-AA × Zn, P = 0.04). A naturally occurring colibacillosis diarrhea outbreak occurred during this experiment. The ZnO addition reduced (P < 0.001) the number of pigs removed and pig-days on antibiotic therapy. In Exp 3, ADFI in wk 2 was improved by Zn and Cu (P < 0.001 and P = 0.09, respectively) with no interactions. In wk 1, G:F was reduced by ZnO only in the absence of Cu (Cu × Zn, P = 0.03). Feeding Zn decreased fecal microbiota diversity in the presence of CuSO(4) but increased it in the presence of Cu-AA (Cu source × Zn, P = 0.06). In Exp. 4, Cu supplementation improved the overall ADG (P = 0.002) and G:F (P < 0.001). The CuSO(4) effect on G:F was greater (P < 0.001) than the Cu-AA effect. Our results indicate that pharmacological amounts of ZnO and Cu (Cu-AA or CuSO(4)) are additive in promoting growth of pigs after weaning.     

Gaseous emissions,growth performance and pork quality of pigs housed in deep‐litter system compared to concrete‐floor system

This study measured gaseous emissions, growth performance and pork quality in a deep‐litter system and concrete‐floor system. Three hundred and twenty weaned piglets with an average body weight (BW) of 6.0 ± 0.3 kg were assigned randomly into three treatments. Treatments 1 and 2 included four pens with 20 pigs for each pen respectively in the deep‐litter system, and the ratio of sawdust to chaff was 5:5 and 3:7 for treatments 1 and 2 respectively, the probiotics inoculated into the fermentation bedding for both treatments were composed of Saccharomycetes, Bacillus subtilis and Actinomycetes; treatment 3 was the conventional concrete‐floor system including eight pens with 20 pigs for each pen. The concentration of NH₃ and CO₂ in the deep‐litter system was significantly (P < 0.001) lower than that in the concrete‐floor system. The ratio of feed to gain for pigs raised in the deep‐litter system was significantly (P < 0.05) lower than that for pigs housed in the concrete‐floor system. The carcass weight and length, color score and rate of cooking meat for pork from the deep‐litter system were significantly (P < 0.05) higher than those from the concrete‐floor system. Results indicate that pigs raised in the deep‐litter system had some animal welfare improvements and an odor nuisance reduction; in the meantime, pork quality also improved from the deep‐litter system compared to the pigs housed in the concrete‐floor system.     

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.     

Effect of feed withdrawal prior to slaughter on prevalence of gastric ulcers in pigs

OBJECTIVE: To determine whether withdrawing feed from pigs prior to slaughter had any effects on prevalence or severity of gastric ulcers. DESIGN: Split-plot design. ANIMALS: 873 pigs. PROCEDURES: At the finishing barn, pigs were assigned to 30 pens. Feed withdrawal times (0, 12, or 24 hours) were assigned to pens at random, and pigs in each pen were marketed in 3 groups over a period of 4 weeks. The first marketing group consisted of the 10 heaviest pigs in each pen, the second consisted of the next 10 heaviest, and the third consisted of all remaining pigs. Feed was withheld from all pigs in each pen prior to removal of each marketing group. Thus, feed was withheld once, twice, or 3 times for pigs in the first, second, and third marketing groups, respectively. RESULTS: Feed withdrawal time was not significantly associated with ulcer score at the time of slaughter. Ulcer scores and prevalence of chronic damage were higher in the third marketing group, regardless of feed withdrawal time. Prevalence of severe damage, prevalence of chronic damage, and prevalence of esophageal constriction increased as carcass weight decreased. No pigs died of gastric ulceration. CONCLUSION AND CLINICAL RELEVANCE: Results suggest that withdrawal of feed from pigs prior to slaughter does not increase damage to the stomach and that repeated feed withdrawal does not result in fatal gastric ulceration.     

The effects of ractopamine on the behavior and physiology of finishing pigs

The objectives of this study were to examine the effects of ractopamine (RAC) on the behavior and physiology of pigs during handling and transport. Twenty-four groups of three gilts were randomly assigned to one of two treatments 4 wk before slaughter: finishing feed plus RAC (10 ppm) or finishing feed alone. Pigs were housed in the same building in adjacent pens with fully slatted floors and ad libitum access to feed and water. Behavioral time budgets were determined in six pens per treatment over a single 24-h period during each week. Behavioral responses of these pigs to routine handling and weighing were determined at the start of the trial and at the end of each week. Heart-rate responses to unfamiliar human presence were measured in all pigs and blood samples were taken from a single pig in each pen on different days during wk 4. At the end of wk 4, all pigs were transported for 22 min to processing. Heart rate was recorded from at least one pig per pen during transport and a postmortem blood sample was taken from those pigs that were previously sampled. During wk 1 and 2, RAC pigs spent more time active (P < 0.05), more time alert (P < 0.05), and less time lying in lateral recumbency (P < 0.05). They also spent more time at the feeder in wk 1 (P < 0.05). At the start of the trial, there were no differences in behavioral responses to handling. However, over each of the next 4 wk, fewer RAC pigs exited the home pen voluntarily, they took longer to remove from the home pen, longer to handle into the weighing scale and needed more pats, slaps, and pushes from the handler to enter the scales. At the end of wk 4, RAC pigs had higher heart rates in the presence of an unfamiliar human (P < 0.05) and during transport (P < 0.05), but not during loading and unloading. Also at the end of wk 4, RAC pigs had higher circulating catecholamine concentrations (P < 0.05) than control pigs. Circulating cortisol concentrations and cortisol responses to transport did not differ between treatments. The results show that ractopamine affected behavior, heart rate, and catecholamine profile of finishing pigs and made them more difficult to handle and potentially more susceptible to handling and transport stress.     

Effects of double stocking and weighing frequency on pig performance in wean-to-finish production systems

Two studies were carried out in different wean-to-finish barns to determine the effects of double stocking on pig growth performance. In Study 1, pigs (n = 1,560) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: initial stocking treatment (Single [52 pigs/pen] vs Double [104 pigs/pen] stocked for 10 wk after weaning) and weighing frequency (High [12 times during the study] vs Low [3 times]) on pig performance from weaning (5.9+/-0.01 kg BW; 17 d of age) to harvest (114+/-0.67 kg BW). Floor and feeder space per pig were 0.650 m2 and 4 cm and 0.325 m2 and 2 cm for the single- and double-stocked treatments, respectively. In Study 2, pigs (n = 1,458) were used in a randomized complete block design to evaluate two initial stocking treatments (Single [27 pigs] vs Double [54 pigs] stocked for 10 wk after weaning) on pig performance from weaning (4.8+/-0.01 kg BW; 15 d of age) to harvest (24 wk after weaning). Floor and feeder space per pig were 0.640 m2 and 3.4 cm and 0.320 m2 and 1.7 cm for single- and double-stocked pens, respectively. In both studies, double-stocked pigs were split at the end of wk 10 into two equal-sized groups of similar mean BW and CV of BW, and one group was moved to a different pen in the same building. In Study 1, performance was not affected (P > 0.10) by frequency of weighing. For the first 10 wk after weaning, the Double compared to the Single treatment had lower ADG (7.7 and 7.9%, for Studies 1 and 2, respectively; P < 0.001) and lighter pigs at wk 10 (6.8 and 7.3%, respectively; P < 0.001). During the first 10 wk in Study 1, Double compared to the Single pigs had lower ADFI (7%; P < 0.001) but similar gain:feed (P > 0.10). From wk 11 to harvest, pigs on Double and Single treatments had similar (P > 0.10) ADG in both studies and, in Study 1, ADFI was unaffected by initial stocking treatment, but double-stocked pigs had greater gain:feed (4%, P < 0.01). Double-stocked pigs required an additional 2 d to reach a fixed harvest BW (P < 0.05) in Study 1 and were lighter (4%; P < 0.05) at 24 wk after weaning in Study 2. Carcass measures were similar (P > 0.10) for double- and single-stocked pigs. Double-stocked pigs that were moved at the end of 10 wk had growth performance similar (P > 0.10) to those that remained in the original pen. In summary, double stocking reduced growth rate to 10 wk after weaning but subsequently had no effect on growth rate and improved feed efficiency.     

Temperature and body weight affect fouling of pig pens

Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg) was studied. Ten groups of 5 pigs were placed in partially slatted pens (60% solid concrete, 40% metal-slatted) in climate respiration chambers. After an adaptation period, temperatures were raised daily for 9 d. Results showed that above certain inflection temperatures (IT; mean 22.6 degrees C, SE = 0.78) the number of excretions (relative to the total number of excretions) on the solid floor increased with temperature (mean increase 9.7%/ degrees C, SE = 1.41). Below the IT, the number of excretions on the solid floor was low and not influenced by temperature (mean 13.2%, SE = 3.5). On average, the IT for excretion on the solid floor decreased with increasing BW, from approximately 25 degrees C at 25 kg to 20 degrees C at 100 kg of BW (P < 0.05). Increasing temperature also affected the pattern and postural lying. The temperature at which a maximum number of pigs lay on the slatted floor (i.e., the IT for lying) decreased from approximately 27 degrees C at 25 kg to 23 degrees C at 100 kg of BW (P < 0.001). At increasing temperatures, pigs lay more on their sides and less against other pigs (P < 0.001). Temperature affects lying and excreting behavior of growing-finishing pigs in partially slatted pens. Above certain IT, pen fouling increases linearly with temperature. Inflection temperatures decrease at increasing BW.     

Behavior of feedlot cattle affects voluntary oral and physical interactions with manila ropes

Providing cattle with access to manila ropes has shown promise as a means of monitoring zoonotic bacteria in pens of feedlot cattle. Studies were conducted to determine the impacts of climate, animal age and BW, number of ropes, duration of placement, and previous rope access on efficacy of ropes as a sampling technique for feedlot cattle. Eight pens of commercial finishing cattle (average 196 +/- 19 animals per pen, 536.7 +/- 22.9 kg) were monitored for a total of 7 d in October of 2003 (commercial study). One rope was tied on the pen railing adjacent to the feed bunk in each pen, and the proportion of animals within the pen contacting the rope was recorded. In a second study, 80 cattle housed in 8 pens (each 270 m(2); 10 animals/pen) were monitored for 1 d/wk using video cameras (video study). Video images were collected for 8 consecutive weeks immediately after weaning (average BW = 252.7 +/- 30.6 kg) and for 6 wk at the end of the finishing period (average BW 541.2 +/- 42.8 kg). In the commercial study, the proportion of cattle contacting the rope per pen increased over the first 6 h to 70% (P < 0.05), although approximately 50% of the cattle contacted the rope within 2 h after placement. A 40 degrees C reduction in ambient temperature on d 6 caused cattle to cease contact with the ropes, although after 6 d of acclimation to reduced ambient temperature, interactions with ropes recovered to 47% of previous values. In the video study, weaned calves required 2 wk of acclimation to the feedlot environment before contact with the rope was maximized. Contact with the rope was most frequent 3 to 8 wk after entry into the feedlot and decreased (P < 0.05) as cattle approached slaughter weight. It is likely that ropes will be most effective at monitoring zoonotic bacteria in pens of cattle during the mid-feeding period where the pen environment is stable and cattle are inquisitive but not highly reactive.     

Effects of eating space and availability of water in feeders on productivity and eating behavior of grower/finisher pigs

Three experiments were conducted to determine the effects of eating space and availability of water within feeders on the productivity and behavior of growing/finishing pigs. In Exp. 1, 12 commercial feeders were classified as being either single-space (SS) or multiple-space (MS), and either as dry (D) or wet/dry (WD), resulting in two SS-D, four MS-D, three SS-WD and three MS-WD models. Each model was evaluated using four pens of 12 pigs, which were fed a mash diet throughout the growing/finishing period (25 to 106 kg). Pigs were videotaped when they were approximately 40 and 80 kg in weight to determine eating behavior. The number of feeding spaces did not affect the productivity of the pigs, but the presence of water within the feeder resulted in increases in ADFI (P < .05) and ADG (P < .05) and a reduction in carcass lean (P < .05). Pigs eating from SS feeders spent 15% less time eating than those fed from two-space feeders (P < .05), and occupancy rate for feeding spaces was increased by 75% (P < .05). The WD feeders also resulted in a reduction (17%) in eatingtime compared to D models (P < .01), and occupancy rate for WD feeders was similarly reduced (P < .05). Pigs spent 16% less time eating when they weighed approximately 80 kg than when they weighed 40 kg (P < .01). In Exp. 2, rate of eating was determined during a short test on the same 12 feeder models for both small (48 kg) and large (90 kg) pigs. Large pigs ate faster than small pigs, but eating rate was not affected by feeding space or presence of water in the feeder. In Exp. 3, eating rate was determined for small amounts of dry or wet feed. Premixing water with the feed (1:1 ratio by weight) increased eating speed (P < .01). We concluded that 12 pigs can be fed from a single-space feeder without affecting productivity. The inclusion of water within a feeder decreases time spent eating, but it increases ADFI and ADG. When pigs are small, they spend more time eating, and feeder occupancy rates are higher than when they are large.     

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.     

Effects of dietary iron level on growth performance,hematological status,and intestinal function in growing-finishing pigs

This study investigated the different addition levels of iron (Fe) in growing-finishing pigs and the effect of different Fe levels on growth performance, hematological status, intestinal barrier function, and intestinal digestion. A total of 1,200 barrows and gilts ([Large White × Landrace] × Duroc) with average initial body weight (BW; 27.74 ± 0.28 kg) were housed in 40 pens of 30 pigs per pen (gilts and barrows in half), blocked by BW and gender, and fed five experimental diets (eight replicate pens per diet). The five experimental diets were control diet (basal diet with no FeSO₄ supplementation), and the basal diet being supplemented with 150, 300, 450, or 600 mg/kg Fe as FeSO₄ diets. The trial lasted for 100 d and was divided into the growing phase (27 to 60 kg of BW) for the first 50 d and the finishing phase (61 to 100 kg of BW) for the last 50 d. The basal diet was formulated with an Fe-free trace mineral premix and contained 203.36 mg/kg total dietary Fe in the growing phase and 216.71 mg/kg in the finishing phase based on ingredient contributions. And at the end of the experiment, eight pigs (four barrows and four gilts) were randomly selected from each treatment (selected one pig per pen) for digesta, blood, and intestinal samples collection. The results showed that the average daily feed intake (P = 0.025), average daily gain (P = 0.020), and BW (P = 0.019) increased linearly in the finishing phase of pigs fed with the diets containing Fe. On the other hand, supplementation with different Fe levels in the diet significantly increased serum iron and transferrin saturation concentrations (P < 0.05), goblet cell numbers of duodenal villous (P < 0.001), and MUC4 mRNA expression (P < 0.05). The apparent ileal digestibility (AID) of amino acids (AA) for pigs in the 450 and 600 mg/kg Fe groups was greater (P < 0.05) than for pigs in the control group. In conclusion, dietary supplementation with 450 to 600 mg/kg Fe improved the growth performance of pigs by changing hematological status and by enhancing intestinal goblet cell differentiation and AID of AA.