Effects of dietary salt level during gestation and lactation on reproductive performance of sows: a cooperative study.

Two experiments involving 1,020 litters were conducted at eight research stations to determine the effects of dietary NaCl (salt) concentration during gestation and lactation on reproductive performance of sows. Primiparous and multiparous sows were fed fortified corn- or grain sorghum-soybean meal diets at 1.82 kg/d during gestation. During the winter months (December, January, February) the feeding level was increased to 2.27 kg/d. Sows had ad libitum access to diets during lactation. Dietary concentrations of added salt were .50 and .25% in Exp. 1 and .25 and .125% in Exp. 2. When more feed was fed during gestation, the salt concentrations were reduced to .40, .20, .20 and .10%, respectively, in order to maintain a constant daily intake of Na and Cl during gestation. Gestation weight gain and lactation (21-d) weight loss of the sows were not affected by dietary salt level in either experiment. In Exp. 1, lowering the salt concentration did not influence the number of pigs farrowed, but it resulted in a .05 kg/pig reduction (P less than .01) in average birth weight. Average 21-d pig weights also tended (P less than .19) to be lower in the low-salt group. There was a decrease in litter size from the first to the second farrowing for sows fed low salt, but not for sows fed the higher salt concentration. In Exp. 2, reducing the salt content from .25 to .125% did not alter reproductive performance. The overall ratio of males to females at birth in the population of greater than 10(4) pigs was 52.3:47.7. Lower salt intakes tended to reduce the percentage of males born in both experiments, although the differences were not significant (P greater than .3). The results indicate that reducing the salt concentration in sows diets from .50 to .25 or .125% reduces birth weight in newborn pigs. When continued for more than one reproductive cycle, feeding less than .5% salt appears to reduce litter size at birth and weaning.

Effect of lasalocid on reproductive performance and subsequent lactation in the sow.

The effect of lasalocid (140 mg . head-1 . d-1) on sow reproductive performance and subsequent piglet performance during lactation were examined in a trial that involved 114 sows. Treatments consisted of 1) control diet with no lasalocid during gestation and lactation; 2) lasalocid diet during gestation, control diet during lactation; 3) control diet during gestation and lasalocid diet during lactation; and 4) lasalocid diet during gestation and lactation. The addition of lasalocid either to gestation or lactation diets had no effect (P greater than .10) on sow weight gains or days to return to estrus postweaning. Milk protein percentages were similar (P greater than .10) for sows in all treatment groups for samples taken at 3, 7 and 14 d postfarrowing. Milk fat percentages were higher (P less than .05) in fall-bred sows at d 3 for Treatments 1, 3 and 4 than for Treatment 2 No significant differences (P less than .10) were observed for litter size at birth, 21 d postfarrowing or at weaning. Piglet weights at birth, 21 d and weaning were similar (P less than .10) among treatment groups. However, litter size and litter weight gains tended to be heavier at 21 d postfarrowing and at weaning for fall-bred sows fed lasalocid in either gestation and (or) lactation compared with those fed the control diet.

Losses to internal parasites in swine production.

Experimental infections of pigs with Strongyloides ransomi, Stephanurus dentatus, Ascaris suum, Oesophagostomum spp. or Trichuris suis at increasing levels generally decrease daily gain and increase feed to gain ratio linearly. At lower, subclinical levels of infection, the feed to gain ratio typically is increased 3% to 6% by an infection. Based on low-level experimental infections with A. suum, the economic loss to producers in the U.S. from increased feed to gain ratio is estimated at $155 million annually.

Effect of diet and exercise on performance, carcass traits and plasma components of growing-finishing barrows.

Twenty-four barrows (approximately 25 kg initial wt) were used in each of three 2 X 2 factorially arranged trials to study effects of exercise (not exercised vs walking 30 min/d, 6 d/wk on a treadmill) and diet (low energy vs high energy) on performance during the growing-finishing period. Average daily gain (ADG) of barrows not exercised was greater (P less than .07) than that of those exercised. Barrows fed the high-energy diet had greater (P less than .05) ADG, lower (P less than .01) feed intake and lower (P less than .01) feed-to-gain ratio than barrows fed low-energy diets. In trials 1 and 2, pigs were slaughtered when removed from test and selected carcass measurements and internal organ weights were obtained. Exercise did not significantly affect carcass length, backfat thickness, loin muscle area or lean cuts (as a percentage of off-test weight). Pigs fed the high-energy diet had more (P less than .01) backfat than those fed the low-energy diet. Neither the exercise program nor the diet had a significant effect on organ weights. Pigs not exercised had a higher (P less than .05) plasma albumin-to-globulin ratio and lower (P less than .05) plasma creatinine concentration than did pigs that were exercised. Also, pigs not exercised had slightly higher (P less than .08) plasma albumin and glucose, but lower (P less than .06) plasma globulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Parasite transmission in confined hogs.

Examinations of fecal specimens from swine of all ages maintained in a totally enclosed confinement facility in south Georgia were conducted in a 5-year survey (1977-1981) to determine the prevalence, intensity, and transmission patterns of intestinal nematode and protozoan parasites. Weaned pigs in the nursery had no detectable parasitic infections except sporadic Isospora suis in newly weaned pigs. Growing-finishing hogs had a low prevalence of Ascaris suum, Oesophagostomum spp. and Balantidium suis. Mean A. suum prevalence and mean eggs per gram feces (EPG) increased until about 200 days of age and then declined. Oesophagostomum spp. and B. suis prevalence and intensity tended to increase throughout life. Gilts (mean age 273 days) in the gestation unit had a higher (P less than 0.01) prevalence of A. suum and lower (P less than 0.01) prevalences of Oesophagostomum spp. and B. suis than sows (mean age 706 days). Similarly, A. suum EPG was higher (P less than 0.01) and Oesophagostomum spp. EPG and B. suis cysts per gram feces (CPG) were lower (P less than 0.01) in gilts than in sows. No evidence for a peri-parturient increase in parasite eggs or cysts was found. Instead, there was a higher prevalence of B. suis (P less than 0.01) in gestating than in lactating animals and more lactating sows than gestating sows were negative for parasites (P less than 0.01). Apparent differences due to location (gestation unit or farrowing unit) were largely attributable to age differences. Trichuris suis infections were rare and not shown to be established in the herd. Strongyloides ransomi in suckling piglets was controlled by anthelmintic therapy. I. suis occurred in piglets throughout the study but was never found in sows in the farrowing unit, either before or after birth of a subsequently infected litter of piglets. No parasites requiring intermediate hosts occurred.

Effect of crossbreeding on genetic improvement of growth and reproduction in pigs.

Nine-year data from 3426 pigs were analyzed to present a retrospective evaluation of purebred, 2-breed crossing, and 3-breed rotational crossbreeding in the sixties and seventies. No significant heterosis effect was observed for litter size and the average number of pigs per litter (10) remained constant as crossbreeding intensified and the management system improved. Parental crossing did not influence sex ratios and no significant deviation from the 50:50 sex ratio occurred throughout the study. Among purebreds, Hampshire pigs were heavier (P less than .05) at birth and weaning than Duroc pigs. Crossbred dams sired by Duroc or Yorkshire boars produced offspring which were comparable in birth and weaning weights, but weighed less (P less than .05) than those sired by Landrace boars. Effect of birth weight on weaning weight of crossbred and purebred pigs was consistently positive whereas litter size influenced weaning weight negatively. Survival of the pigs was not dependent on parental crossing and did not change over the years when crossbreeding intensified. Yearly environmental variation influenced birth weight and weaning weight, but not litter traits. Male pigs were heavier (P less than .01) at birth than females, but the two groups were comparable at weaning.

Reproductive performance of sows fed elevated calcium and phosphorus levels during growth and development.

A cooperative regional study (S-145) involving 586 farrowings was conducted at five state experiment stations (Georgia, Mississippi, South Carolina, Tennessee and Virginia) to determine the influence of feeding elevated Ca and P levels during growth and development on general reproductive efficiency and longevity of confined, housed females kept for three consecutive parities. Two dietary Ca and P levels (100 vs 150% of 1979 NRC-recommended amounts) were fed ad libitum from weaning to 100 kg. A diet containing .8% Ca and .6% P was limit-fed to all gilts and to all sows during gestation and lactation. Growth rate and feed efficiency from weaning to 100 kg were similar (P greater than .10) for gilts fed 100 vs 150% Ca and P levels. A similar total number of litters (292 vs 294) was farrowed by each previous treatment group. From the previously-fed-100% Ca and P group, 78 and 65% of the sows that completed the first parity completed the second and third farrowing, respectively. Similarly, from the previously-fed-150% Ca and P group, 81 and 57% completed the second and third farrowing, respectively. Across all locations, total pigs born, live pigs born, stillborns, birth weight, number and weight of pigs at 21 d of age, sow weight at 110 d of gestation and at weaning did not differ (P greater than .10) between the two previously fed sow groups. There were significant location and farrowing effects, but most two-way interactions with Ca and P levels were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of feeding wheat contaminated with wild radish (Raphanus raphanistrum) to growing pigs.

In each of two growth trials, weanling pigs were individually housed and fed to study the effect of various amounts of wild radish (Raphanus raphanistrum) seed pods in the diet on performance of growing swine. For trial 1, 20 pigs averaging 19.6 kg live weight were divided into four comparable groups of five pigs each based on sex and initial weight and were assigned to fortified wheat-soybean meal diets with: (1) 0%, (2) 1.20%, (3) 3.25%, or (4) 4.95%, by weight, of wild radish seed pods. For trial 2, 15 pigs averaging 20.6 kg live weight were divided into three comparable groups based on sex and initial weight and assigned to fortified wheat-soybean meal diets with: (5) 0%, (6) 7.5%, or (7) 15% of wild radish seed pods. Average daily gains of pigs during the 60 d of trial 1 on all diets were similar (P greater than .05). However, wild radish contamination of the diet had a significant linear effect on feed conversion because the amount of feed required per unit of gain increased (P less than .01) in the amount of feed required to produce a unit of gain. There were no gross symptoms of toxicity in any pigs during the course of either trial or at maturity. Eighteen crossbred barrows averaging 24.8 kg were divided into three comparable groups of six pigs each and assigned to each of the three diets (5, 6 and 7) fed to growing pigs in trial 2, for a digestion and nitrogen balance trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental infections with Hyostrongylus rubidus and the effects on performance of growing pigs.

Pigs infected with Hyostrongylus rubidus at the rate of 550 larvae kg-1 body weight followed 15 days later with 220 larvae kg-1 body weight gained less weight (P less than 0.010) than uninfected control pigs. Feed efficiency (feed/gain) was 8% better (P greater than 0.10) in control than in infected pigs. Peak H. rubidus eggs per gram counts (EPG) occurred 22 days after each infection of pigs. H. rubidus EPG at necropsy were correlated with total number of adults recovered and with female/male ratio. High EPG were associated with H. rubidus populations composed of approximately equal numbers of males and females. Digestion trials consisted of pigs infected with 335 larvae kg-1 body weight compared to uninfected controls. Control pigs had higher (P less than 0.05) crude protein digestion coefficients, excreted less (P less than 0.05) N in feces and had a higher (P less than 0.05) N balance than infected pigs.

Influence of an experimental infection of Ascaris suum on performance of pigs.

Thirty-two pigs (average 26.6 kg live weight) were individually housed and fed to study the effect of an infection of Ascaris suum (either 0, 600, 6,000 or 60,000 A. suum eggs/pig) on performance of growing-finishing pigs. Increasing the level of A. suum infection produced linear (P less than .07) and quadratic (P less than .09) effects on final weight, weight gain and average daily gain. Feed to gain ratio and number of A. suum worms recovered from the intestines of pigs at slaughter increased linearly (P less than .01) with increasing doses of A. suum eggs. Pigs receiving 60,000 A. suum eggs were 13% less (P less than .01) efficient than the noninfected controls. In each of two trials, eight crossbred barrows (15.7 kg in trial 1 and 16.1 kg body weight in trial 2) were examined for the effects of two levels of A. suum infection (0 and 20,000 eggs/pig) on digestibility coefficients for dry matter, crude protein and gross energy. The infection did not affect (P greater than .05) digestibility coefficients during the first two collection periods (d 6 through 10 and 19 through 23). However, digestion coefficients for dry matter, crude protein and gross energy obtained from the total collection period on d 33 through 37 postinfection were greater (P less than .01) for control pigs than for pigs given 20,000 A. suum eggs each. Also, N retention was greater (P less than .05) for control pigs than for infected pigs.

Effect of breed of sire on growth of gilts and on subsequent reproductive performance.

This study was conducted to determine the effect of breed of sire on performance of crossbred gilts during the growing-finishing period and on subsequent reproductive performance for three consecutive parties. Average daily gain of gilts sired by Yorkshire boars was greater (P less than .05) than average daily gain of gilts sired by Landrace boars. Average daily gain of gilts sired by Duroc boars was between that of Yorkshire and Landrace sired gilts, but was not significantly different from either. Birthweight of Duroc and Landrace-sired pigs was heavier (P less than .05) than that of Yorkshire-sired pigs. Landrace-sired pigs were heavier at weaning (35 days of age) than were Duroc and Yorkshire-sired pigs. Sows sired by Yorkshire boars were heavier (P less than .05) when pigs were weaned, at 110 days of gestation and one day post-farrowing than sows sired by Duroc boars. Weight of Landrace-sired sows was intermediate between Yorkshire and Duroc-sired sows and was not significantly different from either. Survival traits were not affected by breed of sire.

Influence of an experimental infection of Strongyloides ransomi on performance of pigs.

Sixty-four pigs (average 21.8 kg live weight) were divided into 16 comparable groups of four, each based on sex and body weight, to study the effects of a single infection of Strongyloides ransomi (either 0, 5,000, 10,000 or 20,000 S. ransomi larvae/kg body weight) on performance during a 91-d trial. Final weight, weight gain and average daily gain of pigs not infected were greater (P less than .01) than those of pigs given either 5,000 or 10,000 S. ransomi larvae/kg body weight, which in turn were greater (P less than .01) than those of pigs given 20,000 S. ransomi larvae/kg body weight. Average daily gain for pigs not infected was 40% greater (P less than .01) than that of pigs given 20,000 S. ransomi larvae/kg body weight. Feed required per unit of weight gain was 44% greater for pigs given 20,000 S. ransomi larvae/kg body weight than for pigs not infected, but this difference was not significantly greater due to extreme variation within the group of infected pigs. In each of two trials, eight crossbred barrows (average 20.0 kg in trial 1 and 22.7 kg body weight in trial 2) were examined for the effects of two levels of S. ransomi infections (0 and 10,000 larvae/kg body weight) on digestion and absorption of nutrients and on N balance. Digestion coefficients for dry matter, crude protein and gross energy for pigs not infected were greater (P less than .05) than for those experimentally infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of exercise during the growing-finishing period on performance, age at puberty and conception rate of gilts.

Littermate gilts were used to study the effects of exercise during the growing-finishing period on performance, age at puberty and conception rate. In trial 1, 12 gilts walked 15 min daily on a treadmill 6 d/wk (Monday through Saturday) until they attained body weights of about 100 kg, while 12 littermate gilts were not forced to exercise. Initial weight and age averaged 24.7 kg and 74 d, respectively. For trial 2, 12 gilts walked 30 min daily 6 d/wk (Monday through Saturday) on a treadmill, while 12 littermate gilts were not exercised. Initial weight and age of these gilts averaged 26.8 kg and 76 d, respectively. The treadmill was operated at 0 slope and at a speed of 2.6 km/h. Within trial, there were no differences (P greater than .05) in weight gain, average daily gain, feed consumed, feed to gain ratio, average backfat depth of loin eye area between gilts exercised and those not exercised. In both trials, there were no differences (P greater than .05) in age at puberty between exercised and nonexercised gilts. In trial 2, 10 gilts were selected in each of the exercised and nonexercised groups and were hand-mated to the same boar on the second estrous cycle. Eight gilts from the exercised group conceived, while nine from the nonexercised group conceived. Four gilts from the nonexercised groups had severe locomotor problems while only one gilt from the exercised groups had difficulty walking.

Influence of an experimental infection of swine kidneyworm (Stephanurus dentatus) on performance of pigs.

Forty pigs (average 25.2 kg live weight) were individually housed and fed to study the effect of a single infection of Stephanurus dentatus (either 0, 72, 457 or 842 S. dentatus larvae/kg body weight) on performance of growing-finishing pigs. Final weight and average daily gain were depressed (P less than .05) by increasing levels of kidneyworm infections. Average daily gain of pigs not infected was 69% greater (P less than .05) than that of pigs given 842 S. dentatus larvae/kg body weight. Feed to gain ratios of pigs were increased linearly (P less than .05) with increasing levels of kidneyworm larvae. Feed to gain ratio for pigs not infected was 24% less (P less than .05) than that for pigs given 842 kidneyworm larvae/kg body weight. In each of two trials, eight crossbred barrows (average 26.0 kg in trial 1 and 22.6 kg body weight in trial 2) were examined for the effects of two levels of kidneyworm infections (0 and 457 larvae/kg body weight) on digestion and absorption of nutrients and on N balance. Digestion coefficients for dry matter, crude protein and energy for pigs not infected and for those experimentally infected were similar (P greater than .05). Pigs not infected had higher (P less than .01) N intakes, excreted more (P less than .05) N in feces and urine and had a higher (P less than .01) N balance than pigs infected with kidneyworms, due largely to difference in feed intake.

Aflatoxicol and aflatoxins B1 and M1 in the tissues of pigs receiving aflatoxin.

Aflatoxicol (AFL) and aflatoxins B1 and M1 were found in tissues (kidney, liver, and muscle) of feeder pigs given an estimated LD50 oral dose of B1 (1.0 mg/kg body weight) provided as a rice culture of Aspergillus flavus and of market-weight pigs fed a naturally contaminated feed, containing aflatoxin B1 at a level of 400 ng/g from corn, for 14 days. The residues in all tissues decreased with time after treatment in both groups, with no detectable residues (approximate detection limits, ng/g, B1 0.03, M1 0.05, AFL 0.01) in pig tissues from the feeding experiment 24 h after withdrawal of aflatoxin-contaminated feed. B1 and M1, when found in the feeding experiment, were at about the same levels in all tissues except the kidney, in which M1 was the dominant aflatoxin. The level of AFL, when detected, was about 10% of the B1 level.

Efficacy of ivermectin against five genera of swine nematodes and the hog louse, Haematopinus suis.

Twenty pigs sequentially infected with Oesophagostomum spp, Metastrongylus spp, and Trichuris suis, and maintained on lots contaminated with Ascaris suum and Strongyloides ransomi, were assigned to 1 of 4 groups on the basis of weight, sex, and litter. Each group of pigs was given ivermectin subcutaneously at the rate of 0, 20, 100, or 500 microgram/kg of body weight. Lice on pigs were counted before treatment, on posttreatment day 1, and just before necropsy. Pigs were necropsied on posttreatment day 6 or 7, and worms were recovered and counted. Efficacies were: 0% to 100% against A suum; 66% to 100% against S ransomi; 99.4% to 99.9% against Metastrongylus spp; 0% against T suis; 3.2% to 635 against adult Oesophagostomum spp; 61.7% to 87.9% against immature Oesophagostomum spp; and 99% to 100% against Haematopinus suis.

Efficacy of fenbendazole against five genera of swine parasites.

Thirty-three pigs were sequentially infected with Oesophagostomum spp, Metastrongylus spp, and Trichuris suis while being maintained in lots contaminated with space Ascaris suum, Strongyloides ransomi, and other parasites. Pigs were assigned to 1 of 3 groups on the basis of weight (6.8 to 25.9 kg), sex, and litter. Pigs in the 1st group were used as nontreated controls; pigs in the 2nd and 3rd groups were given fenbendazole in the feed at doses of 3 and 5 mg/kg of body weight, respectively, on 3 successive days. Pigs were necropsied either on the 4th of 5th day after completion of treatment, and worms were recovered and counted. Based on the mean numbers of worms in the control group, drug efficacies at 3 and 5 mg/kg were, respectively, 100% against A suum; 59% and 81% against S ransomi; 97% and 99.9% against Metastrongylus spp; 94% and 99.7% against T suis; and 99.9% against Oesophagostomum spp.

Effects of forced exercise during gestation on farrowing and weaning performance of swine.

Forty-three gilts and 24 sows were tethered throughout gestation, and one-half were forced to walk on a treadmill 15 min daily 5 days a week. Exercised and nonexercised dams farrowed 10.0 and 10.2 pigs (P greater than .05) and weaned 8.1 and 7.9 (P greater than .05), respectively. Birth weight of pigs born alive from exercised and nonexercised dams averaged 1.6 and 1.5 kg (P greater than .05); weaning weights were 8.5 and 8.2 kg (P greater than .05), respectively. Sows farrowed 12% more pigs (P less than .05) than gilts and weaned 17% more pigs (P less than .05) that were 12% heavier at birth (P less than .01) than those of gilts. Forced exercise did not improve (P greater than .05) reproductive performance as measured by numbers of pigs farrowed and weaned or by birth and weaning weights. Mean length of gestation was not significantly affected by age of dam or exercise treatment. The interval between birth of first and birth of last pig per litter averaged 154 and 151 min (P greater than .05) for exercised gilts and sows, respectively, and 170 and 161 min (P greater than .05) for those not exercised.

Influence of an experimental infection of nodular worms (Oesophagostomum spp.) on performance of pigs.

Four trials were conducted to determine the effect of different levels of nodular worm (Oesophagostomum spp.) infection on the performance of growing-finishing swine and on digestion and absorption of nutrients by the growing pig. In each of two growing-finishing trials, 48 crossbred pigs (average body weight 26.6 kg in trial 1 and 24.4 kg in trial 2) were individually housed and given a single infection of nodular worms (0, 550, 1,100 or 1,650 infective larvae/kg body weight in trial 1 and 0, 1,500, 3,000 or 4,500 infective larvae/kg body weight in trial 2). At 21 days postinfection, pigs given either 1,100 or 1,650 nodular worm larvae/kg body weight required more feed (P less than .05) per unit gain than pigs not infected, but for the 77-day test period, as a whole, nodular worms did not significantly affect performance. in trial 2, pigs given either 3,000 or 4,500 nodular worm larvae/kg body weight were lighter (P less than .05) and gained weight slower (P less than .05) for the first 21 days postinfection than pigs not infected, while pigs given 4,500 larvae gained slower (P less than .05) than pigs on the other three treatments. During the first 21 days after infection, pigs given 4,500 larvae/kg body weight consumed less feed (P less than .05 than pigs given either 0 or 1,500 larvae. Even at the higher levels of infection, nodular worms did not significantly affect performance over the entire 77-day test period. In each of the two other trials, eight crossbred barrows (average body weight 28.8 kg in trial 1 and 28.4 kg body weight in trials 2) were examined for the effects of two levels of nodular worm infection (0 and 4,950 larvae/kg body weight) on digestion and absorption of nutrients and on N balance. Pigs experimentally infected had a lower digestion coefficient for dry matter (P less than .01), ash (P less than .05), crude fiber (P less than .01), N free extract (P less than .05) and N (P less than .05) than noninfected pigs. Pigs not infected with nodular worms had a higher (P less than .05) N balance.

Effect of pyrantel tartrate and carbadox on acquisition of the swine kidneyworm (Stephanurus dentatus) and other parasites by pigs on contaminated lots.

A combination of pyrantel tartrate (106 mg/kg of body weight) and carbadox (55 mg/kg of body weight) in ground feed was fed to 20 weaned pigs (av wt, 14.4 kg) for 42 days. Another group of 20 pigs included nontreated controls. The pigs were farrowed and suckled in a slat-floored farrowing house and had minimal exposure to the small intestinal threadworm (Stronglyoides ransomi) until they were placed on severely contaminated dirt lots at the start of the experiment. Five pigs from each of the two groups were necropsied on day 42. Carbadox was withheld from the feed for the 15 remaining treated pigs. All other pigs were necropsied when they attained market weight, 72 to 83 days layer. Treated pigs killed at market weight had 44% fewer (P less than 0.10) kidneyworms (Stephanurus dentatus) than did control pigs. A 17% increase (P less than 0.01) in the weights of livers of control pigs when compared with treated market-weight pigs was associated with an increase of fibrotic hepatic tissue of control pigs. Worm infections were reduced in the treated market-weight pigs: by 96% (P less than 0.05) for the large roundworm (Ascaris suum), 77% (P less than 0.01) for nodular worms (Oesophagostomum spp), and 64% (P less than 0.01) for the intestinal threadworm. There was some evidence for prophylaxis in market-weight pigs (P less than 0.10) against lungworms (Metastrongylus spp), but none against the whipworm (Trichuris suis) or thick stomach worms (Ascarops strongylina and Physocephalus sexalatus). Pigs given the pyrantel tartrate in feed until attaining market weight maintained a feed-to-gain ratio superior (7.1%) to that of nontreated pigs.