Some aspects of nematode infection in pigs from small herds

Two traditionally maintained, small herds from southern Poland, with 8 and 12 sows, respectively, were surveyed coprologically during 2006-2007. In one of the herds, while deworming a group of sows with levamisole, faecal samples were collected on Day -7, Day 0 (the day of treatment) and Day 10, in order to assess the therapeutic effect of the drug. Coprological investigation was performed also in 26 fatteners originating from other small farms and slaughtered in a local abattoir, with their intestines washed through for the presence of roundworms. In both herds examined, Ascaris suum and Oesophagostomum spp. were prevalent, whilst Trichuris suis appeared only very rarely. Mainly fatteners, replacement gilts and young sows were highly infected with A. suum. The roundworm occurrence in 2- 3-week-old piglets, with the intensity of 300 eggs per gram of faeces (EPG), indicated the possibility of parasite transmission to offspring very early in age. The highest level of Oesophagostomum spp. infection was observed in sows, but weaners were also much affected. For the group of dewormed sows, the mean faecal egg count reduction (FECR) was estimated to be 77.1- 80.4%, suggesting the presence of resistant nodular worms. A very high false-positive A. suum egg counts found in slaughtered animals (240 to 320 EPG) testified to a high contamination level of the environment of small piggeries, as well. Since the reciprocal transmission of parasites between pigs and poultry might occur, it implies that the flocks should be raised separately.     

Prevalence of common gastrointestinal nematode parasites in scavenging pigs of different ages and sexes in eastern centre province, Burkina Faso

The range and infestation intensities of gastrointestinal parasitic nematode species depend on the type of swine production system. The present study focused mainly on nematodes of veterinary importance in scavenging pigs in Burkina Faso, and aimed at determining the prevalence of gastro-intestinal nematode parasites by means of faecal egg per gram (EPG) counts. Between November 2001 and October 2002, faecal samples from 383 pigs of different sexes and ages (< 5 months, 5-12 months and > 12 months) were collected from the rectum and examined for gastrointestinal nematodes parasites using the Mc Master method. Of the 383 pigs examined, 91% were infected by one or more parasites. Ascaris suum (40%; 100-1 400 EPG) was the most prevalent parasite followed by Strongyloides ransomi (21%; 100-4200 EPG), Oesophagostomum spp. (18%; 100-1000 EPG), Hyostrongylus rubidus (11%; 100-1 800 EPG), Globocephalus spp. (10%; 100-400 EPG) and Trichuris suis (1 %; 100-200 EPG). The prevalence was significantly higher in female pigs (n = 239) than in males. In addition, females excreted significantly (P < 0.05) more eggs in their faeces than males, except in the case of Globocephalus spp. The age of the animal had no effect on the prevalence of A. suum whereas there were significant differences in age categories concerning S. ransomi, H. rubidus, Oesophagostumum spp. and Globocephalus spp. Unexpectedly, the high prevalence of these common parasites was not accompanied by elevated EPG values, which suggests the existence of moderate infestations. The present work indicates that the common nematode infestations in pigs do not necessarily need a systematic herd anthelmintic treatment, as only a small number of worms is required to induce immunity. A further study is needed to formulate appropriate and cost-effective strategies for the control of gastro-intestinal nematode parasites in pigs in Burkina Faso.     

Prevalence of helminth infections in swine in Denmark

During 1982-1984 the occurrence of helminths in 66 sow herds was determined by examining faecal samples from swine of different age groups. Ascaris suum was found in 88% of the herds, while Oesophagostomum spp. and Trichuris suis were found in 58 and 23% of the herds, respectively. Strongyloides ransomi and Hyostrongylus rubidus was not identified in any of the herds. The occurrence of both A. suum and Oesophagostomum spp. was strongly related to the age of the animals. A. suum was most frequently found in growing pigs (30% of the fatteners and 25% of the gilts), whereas only 11-19% of the animals of the adult stock were excreting eggs. In contrast the prevalence of Oesophagostomum spp. increased with the age of the hosts, from 10% of the fatteners to 35 and 44% of the sows and boars, respectively. T. suis occurred only very sporadically, with the highest prevalence being 3% in the gilts. In comparison to previous Danish surveys the present mean prevalences of A. suum and Oesophagostomum spp. were low. Extremely low herd prevalences were found among large herds with intensive management and housing. In these herds, the pigs were infected at a later stage in life than pigs in more traditionally managed herds.     

The prevalence of internal and external parasites in pigs of different ages and sexes in Southeast District, Botswana

Botswana imports most pig-based products from neighbouring countries. Pig farming is limited by, among other things, the negative effect of parasites and diseases on production. The object of this study was to determine the prevalence of ecto- and endoparasites in pigs of different ages and sexes in the Southeast District of Botswana. Thirty-nine pigs were sampled for endoparasites and 19 for ectoparasites during a period of 2 1/2 months. Of all the pigs sampled, 54,55% were infected with Ascaris suum, 20,45% with Trichostrongylus spp. and 6,82% with Trichuris suis. Ascaris suum was found to be the most common endoparasite infesting both mature, i.e. 12 months and older, and young, i.e. less than 12 months old, pigs. Although not significantly different (P > 0,05), the prevalence of this parasite species was slightly higher (68,42% with an average of 1,023 +/- 545 eggs per gram (EPG) of faeces per pig) in mature than in young pigs (55% with an of average 1,500 +/- 846 EPG of faeces per pig). The prevalence of Trichostrongylus spp. was lower in mature (5,26% with 20 +/- 14 EPG of faeces per pig) than in young pigs (25% with 22 +/- 9 EPG of faeces per pig). The prevalence of T. suis was also lower in mature (0% infection) than in young pigs (15% with 9 +/- 4 EPG of faeces per pig). The prevalence of the three endoparasite species was not significantly different between the sexes A. suum (1,020 +/- 883 v. 1,503 +/- 522 EPG of faeces per pig), Trichostrongylus spp. (24 +/- 14 v. 18 +/- 8 EPG of faeces per pig) and T. suis (11 +/- 6 v. 2 +/- 4 EPG of faeces per pig) for male and female pigs respectively. Sarcoptes scabiei was the only ectoparasite identified on the pigs sampled for external parasites. It infested 40% of all pigs but the infestation on young pigs (70%) was higher than on the mature ones (33,33%). Since the infection of internal and external parasites was similar in young and old pigs of both sexes, controlling parasites is of great importance since these generally lead to reduced production and are also of public health concern. It is recommended that a further study be carried out to investigate the effect of internal and external parasites on productivity.     

The effect of pre-farrowing treatment of the sow with ivermectin on the early establishment of Ascaris suum and Oesophagostomum spp in the progeny

Residual infective Ascaris suum eggs in farrowing pens provide the initial source of infection for piglets under Swedish management conditions. In such circumstances there is little evidence to support pre-farrowing treatment of the sow specifically against A. suum. The present study shows, however, that ivermectin-treatment of the sow prevents the early establishment of A. suum and Oesophagostomum spp in her litter.     

荣昌县生猪肠道寄生虫感染情况调查

目的摸清重庆市荣昌县生猪的肠道寄生虫感染情况,从而为有效防控猪的肠道寄生虫感染提供依据。方法荣昌是我国著名地方猪“荣昌猪”的故乡,我国养猪大县之一,作者于2007年4月至2007年11月,在该县20个镇选择具有代表性的规模化猪场、散养户和屠宰场,对种公猪、母猪、仔猪及肥育猪肠道寄生虫感染情况和屠宰场宰杀的肥猪肠道寄生虫虫体感染情况进行了调查。共检查了832份集约化饲养猪的粪便、l133份农户散养猪的粪便,并检查了200头屠宰肥猪的肠道。结果13．1％的集约化饲养猪感染猪蛔虫,5．4％感染猪鞭虫．14．6％感染食道口线虫,14．8％感染球虫（包括艾关尔球虫及等孢球虫）,3．6％感染结肠小袋纤毛虫。对散养猪．这些数值分别是6．7％,4．8％,23．2％,13．8％,及4．9％。4％的宰杀肥猪检出猪蛔虫,3．5％检出猪鞭虫,52．0％感染食道口线虫。混合感染很常见。结论本项调查表明,荣昌生猪的寄生虫感染较为严重,应引起有关方面的足够重视。应尽快开展猪肠道寄生虫感染的综合防控工作,以保障养猪业的健康快速发展。     

Endoparasites in swine in different age groups and management systems

In different age groups endoparasites are of varying importance. Sows are predominantly infected with gastrointestinal strongyles (mainly Oesophagostomum spp.), Ascaris suum and Eimeriae, to a lesset extent with Trichuris suis, Hyostrongylus rubidus, Strongyloides ransomi or Isospora suis, while in suckling piglets I. suis and occasionally S. ransomi frequently occur. Weaners and fatteners are infected with coccidia and gastrointestinal strongyles, later with A. suum. Whipworms are also found occasionally. I suis causes diarrhoea in suckling piglets, while in older animals the infection is not correlated with disease. Damage induced by helminths is mainly due to reduced performance, in the case of ascarosis to reduced carcass value. Therefore planned antiparasitic measures should be taken at all stages of pig keeping. Hygienic measures can reduce infection pressure; however parasite elimination is difficult to obtain under conventional management conditions. Consequently the control of parasitic infection at the early stage of piglet production is desirable.     

Efficacy of an in-feed preparation of ivermectin against endoparasites and scabies mites in swine.

In 2 trials, the efficacy of an in-feed preparation of ivermectin was evaluated in 40 pigs naturally infected with endoparasites and Sarcoptes scabiei var suis. Treated pigs (n = 10 in each trial) were fed a ration containing 2 ppm ivermectin for 7 days, followed by consumption of a nonmedicated ration for the remainder of the trial. Control pigs (n = 10 in each trial) were fed a complete, nonmedicated ration for the duration of the trial. Pigs in trial A were monitored for 14 days after treatment; those in trial B were monitored for 35 days after treatment. In trial A, treatment efficacy of ivermectin was 100% against Ascaris suum, Physocephalus sexalatus, Oesophagostomum dentatum, O brevicaudum, Metastrongylus spp; 99.8% against Ascarops strongylina; 90.9% against Trichuris suis; and 13.1% against Macracanthorhynchus hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were observed between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Oesophagostomum spp. On posttreatment day 14, S scabiei were not found in any scrapings taken from treated pigs, but were found in scrapings from 3 of 10 control pigs. The number of infested pigs in the treatment group was not statistically different from the number of infested pigs in the control group. In trial B, treatment efficacy was 100% for A suum and Metastrongylus spp; 96.9% for Ascarops strongylina; and 76.9% for M hirudinaceus. At the terminus of the trial, statistically significant (P less than 0.05) differences were evident between numbers of treated and control pigs infected with A suum, Ascarops strongylina, and Metastrongylus spp.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survey of internal parasites in Western Australian pig herds. 1. Prevalence

Between September 1982 and March 1984, 101 Western Australian piggeries with 15 or more sows were surveyed to determine the prevalence of internal parasites and examine the relationship between parasitism and management practices. Faecal samples were collected from 20 pigs in 4 age groups in randomly selected piggeries, and examined for the presence of eggs of helminth parasites and protozoan cysts. Evidence of nematode parasites was found in 79% of piggeries. Sows were more commonly affected than other classes of pigs with worm eggs being found in 68% of herds. Oesophagostomum spp was the most prevalent worm species, being found in pigs from 65% of piggeries and in sows in 60% of herds. Ascaris suum was the most common species of worm found in growing pigs. There was no evidence of infection with either Metastrongylus spp or Strongyloides spp in any of the herds sampled. Oocysts of coccidia were found in pigs from 56% of piggeries and Balantidium coli cysts were detected in pigs from 42% of piggeries sampled.     

Prevalence of Isospora suis and Eimeria spp. in suckling piglets and sows in Poland

The aim of this investigation was to determine the prevalence of coccidian infections in suckling piglets and sows in Poland. The research was carried out in 14 out of 16 Polish provinces in the years 2003-2005. The investigation was conducted on three types of farms: large farms (>100 sows), medium farms (25-100 sows) and small farms (<25 sows). Diarrhoea of unweaned piglets was observed on all the examined farms. Overall, 780 litters of suckling piglets from 104 farms and 267 mother sows were examined. The faeces were analyzed with the modified McMaster method. Isopsora suis was found in 217 (27.8%) litters from 70 (66.7%) farms. Eimeria spp. was detected only in 20 (2.6%) litters from 12 (11.5%) farms. On the large farms I. suis infection was detected in 31.7% of litters whereas Eimeria spp. in 1.4% of them. On the medium sized farms I. suis was found in 18.1% of litters and Eimeria spp. in 0.6%. On the small farms I. suis was detected in only 13.2% of litters, whereas Eimeria spp. in as many as 28.9%. I. suis and Eimeria spp. oocysts were found in 18 (6.7%) and 16 (6%) sows respectively. From 72 sows producing I. suis infected piglets only 12 (16.7%) shed I. suis oocysts and as little as 4 (5.6%) shed Eimeria oocysts. In the remaining 56 sows (77.8%) no cases of coccidian infections were detected. The results of this investigation demonstrate the high prevalence of I. suis in suckling piglets on the large swine farms in Poland.     

The prevalence of isospora suis and strongyloides ransomi in suckling piglets in the Netherlands

Summary

Faecal samples from suckling piglets from 113 litters on 25 farms in the Netherlands were examined to study the prevalence of gastrointestinal parasites, in particular Strongyloides ransomi and Isospora suis. S. ransomi was not found but I. suis was demonstrated in 17 of the 25 farms and in 41 out of 77 litters of these farms (53%). No other parasites were found. On the basis of these results, a longitudinal study on the incidence and significance of I. suis was performed on 10 farms (5 litters/farm). I. suis was found on 9 out of 10 farms and in 56% of the litters. Farms differed in infection levels, measured as the numbers of patent litters, and in the onset of patency. Other parasites were only found in faecal samples from the sows and from farrowing pens. These were, in order of prevalence, Balantidium coli, Ascaris suum, Eimeria spinosa, E. debliecki and E. suis.     

Porcine coccidia in Papua New Guinea

Faecal samples from 232 domestic pigs raised on concrete, 98 free-ranging village pigs, and five wild boar showed 46.6 (108/232), 54 (53/98) and 80% (4/5) prevalence of coccidian oocysts, respectively. Eight species of Eimeria, and Isospora suis, were recovered. In their descending order of predominance in the pigs raised on concrete, the species of coccidia were E. debliecki (26.7%), E. scabra (22.4%), E. neodebliecki (19.8%), E. porci (15.5%), E. suis (11.6%), E. polita (8.6%), E. perminuta (7%), E. spinosa (5.6%) and I. suis (3.9%). The first five species listed above predominated in the village pigs as well. E. polita, E. spinosa and I. suis were not found in the wild boar. I. suis oocysts prevailed in 8.3% of the 36 sows on concrete, and in 11.1% (3/27) of those which were positive for coccidia. Isosporoid oocysts were absent in the village sows. Of the 125 less than 24-day-old piglets, 29.6% were diarrhoeic, and of these, 43.2% were positive for coccidia. Four of the 16 (25%) coccidia-positive, diarrhoeic piglets, and four of the 37 (10.8%) coccidia-positive non-diarrhoeic piglets shed I. suis oocysts, an observation which seems to weaken the present contention that I. suis is the primary causative agent of neonatal porcine coccidiosis. The highest mean number of oocysts per gram faeces (23,550) was recorded from the diarrhoeic farm piglets on concrete, and the lowest of 6,100 from the gestating farm sows. Mean opg data revealed very little significant quantitative variation between the corresponding age groups of the free-ranging village pigs and the commercially-farmed ones. One of the most interesting findings in the study was that the sows were more frequently infected than all other age groups.     

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.     

Farrowing induction induces transient alterations in prolactin concentrations and colostrum composition in primiparous sows

Hormonal changes involved in the farrowing process partly control the initiation of lactation. Inducing farrowing by injection of PG may alter the normal prepartum hormonal cascade. The aim of the study was to investigate the consequences of farrowing induction on colostrum yield and composition, as well as newborn piglet growth. Gilts were treated with 2 mg of alfaprostol on d 113 of gestation (induced farrowing, IF, n = 9) or were injected with 1 mL of a saline solution (natural farrowing, NF, n = 11). Colostrum production was estimated during 24 h, starting at the onset of parturition, based on piglet BW gains. Colostrum samples were collected during the 36 h after the onset of parturition. Blood samples were collected from sows as of d 112 of pregnancy until d 2 postpartum (d 0 being the day of parturition). Piglet blood samples were obtained at birth, on d 1, and on d 21. Litter size and litter weight at birth did not differ between groups (P > 0.10). Farrowing induction did not influence (P > 0.10) colostrum yield (3.96 ± 0.20 kg) or piglet BW gain during d 1 postpartum (116 ± 8 g). At the onset of farrowing (T0), lactose content in colostrum was greater in IF sows than in NF sows (P < 0.05), whereas colostrum ash and protein contents were less (P < 0.05) in IF sows. Concentrations of IgG in colostrum were similar in both groups of sows, whereas concentrations of IgA at T0 were less in IF than in NF sows (P < 0.01). Overall, endocrine changes in blood from d -2 until d 2 (cortisol, prolactin, progesterone, and estradiol-17β) were not altered by farrowing induction (P > 0.10), but 1 h after the injection of alfaprostol, IF sows had greater circulating concentrations of prolactin (P < 0.01) and cortisol (P < 0.10) than NF sows. The greater concentration of lactose in colostrum from IF sows could be attributed to this transient increase in prolactin and cortisol. At birth, concentrations of white blood cells were less in piglets born from IF sows (P < 0.01). On d 1 and 21, piglets from IF sows had similar IgG concentrations in plasma to piglets from NF sows (P > 0.1). In conclusion, farrowing induction at 113 d of pregnancy induced transient hormonal changes in sows and alterations in colostrum composition, without significantly affecting colostrum yield. It also modified some hematological variables of piglets at birth.     

Socializing piglets before weaning: effects on behavior of lactating sows, pre- and postweaning behavior, and performance of piglets

This study evaluated how socializing piglets before weaning affects behavior of lactating sows and the pre- and postweaning behavior and performance of piglets. Two farrowing rooms, each with 6 pens, and 1 nursery with 4 pens were used. In total, data were obtained from 24 sows and their litters. In each farrowing room, the solid barriers between 3 farrowing pens were removed on d 12 after farrowing, and the sows remained confined in their crates (experimental group). In the other 3 farrowing pens of each farrowing room, sows and their litters were kept under conventional conditions until weaning (control group). All piglets were weaned 28 d after birth. After weaning, piglets from each group remained together in 1 pen of the nursery. The behavior of sows (lying, standing, sitting, nursing) and piglets (lying, active, suckling) in the farrowing rooms was observed for 24 h before and for 48 h after removal of the barriers between the pens. In addition, behavior (active, lying, feeding, agonistic behavior) of piglets was observed in the nursery during the initial 48-h period after weaning. Each piglet was weighed on d 5, 12, and 28 after birth and thereafter weekly until the fifth week of rearing. In the farrowing room, mixing of litters did not influence behavior of piglets and sows. Preweaning weight gain of the piglets did not differ (P = 0.60) between the treatments. In the initial 48 h after weaning, less agonistic behavior (P < 0.001) was observed in piglets belonging to the experimental group. During 5 wk of rearing, piglets in the experimental group gained more weight compared with the control group (P = 0.05). The advantage shown by the experimental group became especially conspicuous in the first week after weaning (P = 0.05). By socializing unfamiliar piglets before weaning, stress due to mixing could at least be distanced in time from the other burdens of weaning, thereby improving performance.     

A survey of gastrointestinal parasites in pigs of the Plateau and Rivers States, Nigeria

Faecal samples were collected from a total of 1,000 pigs from the Port Harcourt and Jos areas of the Rivers and Plateau States, respectively, between January 1987 and March 1988. In the Jos area the parasite incidence was: Ascaris suum 53.1%, Trichuris suis 8.5%, Hyostrongylus rubidus 13.1%, Metastrongylus salmi 3.7%, Strongyloides ransomi 87.7%, Oesophagostomum dentatum 35.1% and Eimeria spp. 2.4% while in Port Harcourt the incidence rate was Ascaris suum 10.4%, Trichuris suis 47.2%, Oesophagostomum dentatum 50%, Hyostrongylus rubidus 2%, Ancylostoma duodenale 83.2% and Eimeria spp. 3.6%. The high rate of parasitic infections was due to poor management practices as shown by poor sanitary conditions. Access to human faeces, poor feeding and lack of deworming were also very evident. The different rates in the incidence of parasites in Jos and Port Harcourt areas were due to the varying moisture conditions in these states.     

Control of Isospora suis-induced coccidiosis on a swine farm

Results of a program designed to control neonatal porcine coccidiosis on a total confinement, farrow-to-finish swine farm are reported. The control program consisted of washing, phenol disinfection, and steam cleaning of farrowing houses and treatment of sows with amprolium HCl before and after farrowing. Before initiation of the control program, 88.9% of the sows examined in the farrowing house were negative for coccidian oocysts, 9.9% were positive for Eimeria spp, and 1.2% were positive for Isospora suis. Most pigs nursing on sows before initiation of the control program had diarrhea at 5 to 10 days of age, which led to dehydration and weight loss. Morbidity was high, and mortality was moderate. Composite fecal samples from these litters were all positive (100%) for I suis. After initiation of the control program, 99.6% of the sows examined in the farrowing house were negative for coccidian oocysts and 0.4% were positive for Eimeria spp. Clinical signs of coccidiosis were rarely present in nursing pigs examined after the control program was initiated; however, I suis was still present in 19.8% of the composite fecal samples from pigs examined. An association between oocyst production in sows and I suis infections in pigs was not found in the present study. Oocysts of Eimeria spp were not found in the feces from the pigs.     

Helminth infections in Danish organic swine herds

In nine organic swine herds, faecal excretion and pasture contamination by parasite eggs/larvae were studied in a period from March to October 1999. It was shown that the organic pigs were infected with Ascaris suum (28% of weaners, 33% of fatteners, 4% of sows), Trichuris suis (4% of weaners, 13% of fatteners, <1% of sows) and Oesophagostomum spp. (5% of weaners, 14% of fatteners, 20% of sows) whereas no infections with Hyostrongylus rubidus, Metastrongylus spp. or Strongyloides ransomi were detected. Moreover, no pigs showed clinical signs of infestations with scabies or lice. In the soil samples, very few Trichuris eggs were found throughout the season, whereas Ascaris eggs were found in 14% of the soil samples from sow pastures and in 35% from slaughter pig pastures, with the first infective eggs being recorded in July and the maximum number in August. Infective Oesophagostomum larvae were found in the grass samples in increasing numbers from May to October. Single herd cases of exceptionally high parasite infection levels are described in relation to herd management procedures.     

Efficacy of an in-feed ivermectin formulation against gastrointestinal helminths, lungworms, and sarcoptic mites in swine

The efficacy of ivermectin as an in-feed formulation was evaluated against naturally acquired gastrointestinal helminths, lungworms, and sarcoptic mites (experiment 1; n = 24) and against induced infection with intestinal nematodes (experiment 2; n = 24) in pigs. Treatments consisted of ivermectin administered in feed at concentrations calculated to provide 100 or 200 micrograms/kg of body weight/d for 7 days or of nonmedicated feed (controls) for 7 days. At concentration of 100 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 97.7% for Ascaris suum, 97.8% for Metastrongylus spp, greater than 99% for Oesophagostomum spp, 100% for Macracanthorhynchus hirudinaceus, and 89.7% for Ascarops strongylina. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 96.9% for Oesophagostomum spp. At concentration of 200 micrograms of ivermectin/kg/d, efficacy against naturally acquired infections was 100% for A suum, Hyostrongylus rubidus, Metastrongylus spp, and Ascarops strongylina; greater than 99% for Oesophagostomum spp; and 85.9% for Macracanthorhynchus hirudinaceus. Against induced infections (fourth-stage larvae), efficacy was 100% for A suum and 95% for Oesophagostomum spp. At concentrations of 100 and 200 micrograms of ivermectin/kg/d, efficacy against Sarcoptes scabiei var suis was evidenced by elimination of the mite by posttreatment day 14.     

Riboflavin requirement of lactating swine

Twenty-five crossbred gilts and 25 crossbred sows were used in an experiment to estimate the riboflavin requirement of lactating swine. During gestation the females were fed a 12% crude protein, corn-soybean meal diet that was marginal in riboflavin content, i.e., 2.3 mg/kg. After farrowing, litter size was equalized across lactation diets within each parity category. The basal, 14% crude-protein corn-soybean meal lactation diet was supplemented to provide five levels of dietary riboflavin: 1.25, 2.25, 3.25, 4.25 and 5.25 mg/kg. Five gilts and five sows were fed each dietary treatment. Each dam was provided her assigned diet ad libitum during the 24-d lactation; piglets were not provided supplemental feed. The erythrocyte glutathione reductase activity coefficient (EGRAC), an indicator of riboflavin status, was measured on blood samples obtained from the dams and their piglets on d 1 and d 24 postpartum. On d 1, the mean EGRAC of gilts was slightly higher than that of sows, while piglet EGRAC was similar regardless of maternal age. On d 24 gilts and their piglets had higher average EGRAC (P less than .01) than did sows and their piglets. Thus, there was a treatment x dam age interaction (P less than .05). Lactation performance criteria gave further evidence of similar treatment x age group interactions. Gilts fed the diet containing 1.25 ppm riboflavin had higher piglet mortality, consumed less feed and lost more weight (P less than .05) for each criterion than did sows fed the same diet. Despite these observations, the broken-line estimates of the riboflavin requirement, based on EGRAC, for gilts and sows were 16.3 and 16.2 mg/d, respectively. The EGRAC values for piglets closely paralleled those of their dams regardless of treatment, suggesting that there is no mechanism to protect the nursing piglets from a maternal dietary deficiency of riboflavin.