Occurrence and spread of influenza A(H1N1)pdm09 virus infection in Norwegian pig herds based on active serosurveillance from 2010 to 2014.

The incursion of influenza A(H1N1)pdm09 virus was detected by Norway's active serosurveillance of its pig population in 2009. Since then, surveillance data from 2010 to 2014 revealed that 54% of 5643 herd tests involving 1567 pig herds and 28% of 23 036 blood samples screened positive for antibodies against influenza A virus. Positive herds were confirmed to have influenza A(H1N1)pdm09 virus infection by haemagglutination inhibition test. In 50% of positive herd tests, ⩾60% of the sampled pigs in each herd had antibodies against influenza A(H1N1)pdm09 virus. This within-herd animal seroprevalence did not vary for type of production, herd size or year of test. The overall running mean of national herd seroprevalence, and annual herd incidence risks fluctuated narrowly around the means of 45% and 32%, respectively, with the highest levels recorded in the three densest pig-producing counties. The probability of a herd being seropositive varied in the five production classes, which were sow pools, multiplier herds, conventional sow herds, nucleus herds, and fattening herds in descending order of likelihood. Large herds were more likely to be seropositive. Seropositive herds were highly likely to be seropositive the following year. The study shows that influenza A(H1N1)pdm09 virus is established in the Norwegian pig population with recurrent and new herd infections every year with the national herd seroprevalence in 2014 hovering at around 43% (95% confidence interval 40-46%).

Infrared thermography as a possible technique for the estimation of parturition onset in sows.

BACKGROUND: This study explores the possibility of using infrared thermography to estimate the onset of parturition in sows. Infrared camera (IRC) and infrared laser thermometer (IRT) were used to obtain the auricular skin temperature of sows along with rectal temperatures, from approximately one week before the anticipated farrowing until 24 h post-partum. Three commercial piglet producing farms were included in the study. RESULTS: There were large variations in observed auricular skin temperature, both by IRC and IRT per time point. Graphical exploration of the observed auricular skin temperature measured by the two methods showed the same parallel patterns, although temperatures measured by IRC were higher at any time point compared to IRT. Auricular skin thermography revealed a clear increase in temperatures before farrowing. Statistical analyses, adjusting for differences between farms, sow activity and respiration rate, confirmed this increase. When controlling for these variables, and comparing the baseline temperatures to temperatures at farrowing, the difference was 3.9 and 4.1 °C measured with IRT and IRC, respectively. The greatest increase, of more than 2 °C, was found between 16 and 8 h and 8 to 4 h before farrowing. Rectal temperature increased by 0.5 °C in the same time interval and reached a temperature peak after farrowing. CONCLUSION: Sows showed a more than 2 °C increase in auricular skin temperature, measured by either IRC or IRT, 8 to16 hours before the first piglet was born. Hence, monitoring auricular skin temperatures of sows using infrared thermography one week before expected farrowing may provide a baseline temperature for each sow from which a sudden rise is indicative of parturition in the following 8 to 16 h. This may lead to more efficient allocation of human assistance during farrowing time and thereby improve farrowing management and the welfare of sows and their offspring.

Beneficial antioxidant status of piglets from sows fed selenomethionine compared with piglets from sows fed sodium selenite.

BACKGROUND: Studies in mammals proved dietary organic selenium (Se) being superior to inorganic Se regarding effects on growth performance, antioxidative status, immune response, and Se homeostasis. However, the picture of possible effects of different Se sources and - levels can be expanded. The present field study evaluated the effects on weight gain, hematological and selected biochemical variables as well as plasma concentrations of vitamin E (vitE), total Se and selenobiomolecules in piglets throughout the suckling period. METHODS: Piglets were monitored from birth to 38 days of age (d). The mother sows' diets were enriched with l-selenomethionine (SeMet-0.26 and -0.43 mg Se/kg feed) or sodium selenite (NaSe-0.40 and -0.60 mg Se/kg feed) from 1 month prior to farrowing until the end of lactation period. Piglets received pelleted feed supplemented with Se similarly to the sows' diets from one week of age. Selenite at 0.40 mg Se/kg (NaSe-0.40) represents a common Se source and -level in pig feed and served as control diet. RESULTS: From 24d, piglets in SeMet-groups had higher mean body weight (BW) compared with piglets from sows fed NaSe-0.40. Furthermore, from five-d and above, piglets from sows fed NaSe-0.60 had significantly higher BW than offspring from sows fed NaSe-0.40. Neonatal piglets in group SeMet-0.43 had significantly lower red blood cell counts (RBC), hemoglobin (Hgb) and hematocrit (Hct) concentrations compared with piglets from sows fed with NaSe-0.40. Neonatal and 5d-old piglets in group SeMet-0.26 showed higher gamma-glutamyl transferase activity than piglets in group NaSe-0.40. From five d and above, group NaSe-0.60 excelled with increased specific hematological variables culminating at age 38d with increased Hct, mean corpuscular volume (MCV), and MC hemoglobin (MCH) as well as increased activities of aspartate transaminase and lactate dehydrogenase compared with the other groups. Generally, offspring in the SeMet groups had higher total Se-concentrations in plasma than those from sows fed selenite, and showed a dose-response effect on plasma Se-concentrations. Furthermore, SeMet-fed piglets had higher plasma levels of the selenoproteins (Sel) glutathione peroxidase 3 (GPx3) and SelP as well as selenoalbumin. Plasma vitE levels were significantly negatively correlated with RBC throughout trial period. CONCLUSIONS: Maternal supplementation with SeMet during gestation influenced hematology and clinical biochemistry in neonatal piglets in a different way than in offspring from sows receiving selenite enriched diets. Growth performance was positively influenced by both dietary Se source and Se level. Higher plasma levels of GPx3 observed in piglets receiving SeMet probably improved the protection against birth or growth related oxidative stress. These might prime the piglets for demanding situations as indicated by higher weight gain in offspring from sows fed with SeMet-supplemented diets. Our results on some enzyme activities might indicate that piglets fed NaSe-0.60 had to cope with increased levels of oxidative stress compared with those originating from sows fed SeMet or lower dietary levels of selenite. We assume that combining inorganic and organic Se sources in complete feed for breeding sows might be beneficial fro reproduction and the offspring's performance.

Preweaning mortality in piglets in loose-housed herds: etiology and prevalence.

Preweaning mortality in piglets is a welfare issue, as well as an ethical and economic concern in commercial pig farming. Studying the causes of preweaning mortality and their prevalence is necessary to reduce losses. Preweaning piglet mortality was investigated in a field study including 347 sows from 14 loose-housed Norwegian piglet-producing herds. A total of 5254 piglets were born in these herds during the study period, and 1200 piglets were necropsied. The cause of death was based on pathoanatomical diagnosis (PAD). Preweaning mortality of all piglets in the study was 23.4%, including 6.3% stillborn. The two main causes of preweaning mortality in live-born piglets (n=4924) were trauma (7.1%) and starvation (2.7%). Piglets dying of an infection accounted for 2.0%. Among the necropsied piglets (n=1200), 29.1% had died due to trauma, 26.8% were categorized as stillborn and 11% had died of starvation. Piglets that had died of trauma, had a mean time of death of 1 lactation day (LD 1), ranging from LD 0 to LD 21. The mean time of death of piglets that died due to bacterial infection was LD 9, ranging from LD 0 to LD 31, with Escherichia coli accounting for most infections found in necropsied piglets. Farmers were able to identify death by trauma in piglets, but were less able to identify death due to hunger. Most piglets that died in the preweaning period, died of trauma. Surprisingly, this included large and well-fed piglets. The second most prevalent cause of preweaning mortality was starvation. Improved monitoring may reveal piglets with low body mass index, and additional nutrition may contribute to increase the survival rate.

Zinc oxide enriched peat influence Escherichia coli infection related diarrhea, growth rates, serum and tissue zinc levels in Norwegian piglets around weaning: five case herd trials.

BACKGROUND: Zinc oxide (ZnO), commonly used to control post-weaning diarrhea in piglets, has been highlighted as of potential concern from an environmental perspective. The aim of this field trial was to examine effects of different sources and levels of ZnO added to peat on average daily weight gain (ADG), fecal score in pens and serum and tissue zinc (Zn) levels around time of weaning in order to reduce the environmental impact without loss of the beneficial effect of ZnO on intestinal health and growth. Five case herds with enterotoxic colibacillosis challenges were included. The piglets entered the study aged three or five weeks. All piglets received a commercial diet containing <150 mg Zn/ per kg of complete feed. Four treatment groups received commercial peat added A: uncoated ZnO, B: lipid microencapsulated ZnO, C: solely commercial peat or D: no peat (Farms 2 and 3). RESULTS: At Farms 1, 2 and 3, a significant effect of treatment was identified for fecal score (P < 0.05). Treatment A led to lower fecal scores compared to treatments C (P < 0.05) and D (P < 0.01). At Farms 2 and 3, there was a significant difference in individual average daily weight gain (iADG) between treatment A and D (P < 0.05). The iADG of piglets receiving treatment B did not differ significantly from treatment A. CONCLUSIONS: In 2016, The European Medicines Agency's Committee on Veterinary Medicinal Products concluded that the benefits of ZnO for the prevention of diarrhea in pigs do not outweigh the risks to the environment. Effective alternative measures to reduce the accumulation of Zn in the environment have not been identified. Our results imply that peat added low concentration of both coated and uncoated ZnO influences the gut health of weaned piglets reflected by enhanced weight gain and reduced occurrence of diarrhea. This preventive approach certainly represents a favourable alternative in the "One Health" perspective. It will also contribute to reduced antibiotic use in pig farming while diminishing the environmental consequences caused by ZnO.

Can a super sow be a robust sow? Consequences of litter investment in purebred and crossbred sows of different parities.

The aim of this project was to study the consequences of litter investment on physical characteristics in primiparous and multiparous sows in 3 Norwegian breeds (Norsvin Duroc [ = 12], Norsvin Landrace [ = 12], and crossbreeds [Norsvin Landrace and Swedish Yorkshire { = 15}]). We predicted that the maternal sow line (Norsvin Landrace) would invest more in their litter in term of higher weight at birth, resulting in a higher litter weight of weaned piglets but with the consequence of greater loss in body condition and a higher prevalence of shoulder lesions. It was predicted that this should be more pronounced in primiparous sows than in multiparous sows. As predicted, the maternal pure line (Norsvin Landrace) had higher litter investment in terms of litter weight at birth ( = 0.003) and litter weight at weaning ( = 0.050) as well as higher total litter investment (litter weight at weaning plus weight of dead piglets [stillborn and mummified piglets and weight of piglets that died after farrowing but before weaning]; = 0.050) and suffered larger losses of body condition ( = 0.016) and had a higher prevalence of shoulder lesions ( = 0.008) during lactation than other breeds. Moreover, only in Norsvin Landrace was development of shoulder lesions related to inadequate feed consumption ( = 0.006). This has become a major welfare concern of modern pig breeding. Although primiparous and multiparous sows had similar litter sizes, primiparous sows had lower litter investment in terms of litter weight at birth ( = 0.032) and litter weight at weaning ( = 0.007) as well as total litter investment ( = 0.008). Primiparous sows suffered greater losses in body condition ( = 0.012) and developed more shoulder lesions ( = 0.026) due to lower total feed consumption ( < 0.001) during lactation than multiparous sows. Especially in the highly productive maternal line (Norsvin Landrace), development of shoulder lesions during the lactation period was more pronounced in primiparous sows than in multiparous sows ( < 0.001). The selection program has shifted the balance to greater investments in earlier life, when sows still need resources for their own growth and development. This has resulted in a larger number of weaned piglets but at a higher sow welfare cost in terms of higher losses in body condition and a higher prevalence of shoulder lesions. Our results pinpoint the importance of improving the balance between economic traits and traits that improve welfare and longevity of the sows.

The association between immunoglobulin G in sow colostrum and piglet plasma.

Colostrum provides newborn piglets with energy and passive immunity and is essential for survival of the piglets. The plasma concentration of immunoglobulin G (IgG) in piglets is dependent on several factors, most importantly the concentration of IgG in sow colostrum (colostrum IgG). The main aims of this study were to investigate the variation in concentration of colostrum IgG between herds and the individual sows within herd and to investigate factors associated with plasma IgG concentrations in piglets (piglet IgG). From 4 herds (A to D), 876 piglets from 62 sows were included in the study. Colostrum was sampled from sows immediately after expulsion of the first piglet and before the first suckling (t1), midway through farrowing (just after the sixth piglet was born; t2), and after the last piglet was born (t3). At d 1, 0.5 mL blood from piglets was collected in tubes containing EDTA, and IgG concentrations were analyzed. Mean colostrum IgG concentration across all herds was 53.9 g/L. Herd A had mean colostrum IgG of 38.3 g/L, whereas the other 3 herds (B,C, and D) had mean colostrum IgG of 47.4, 60.4, and 67.8 g/L, respectively. Colostrum IgG at t1, t2, and t3 across all herds was 56.2, 53.7, and 42.5 g/L, respectively. Mean concentration of piglet IgG across all samplings was 21.7 g/L. Multilevel linear regression analysis was performed with piglet IgG (g/L) as outcome. In this model, the herd effect accounted for 9% of the total variance and 34% of the variance resided at sow level. Piglet IgG was associated with herd, birth order (), body mass index (BMI) > 17 (kg/m), and colostrum IgG at t1 (g/L) with an overall -value < 0.01. Herd D had the highest predicted mean level of piglet IgG. The main model predicted that piglet IgG decreased linearly by 0.4 g/L with each piglet born ( < 0.01). The model also predicted an increase by 0.1 g/L for each gram per liter extra colostrum IgG in colostrum ( = 0.03). Piglets with a BMI above 17 kg/m had a greater piglet IgG (+4.5 g/L) than those with a BMI at 17 kg/m or below ( < 0.01). Concentrations of colostrum IgG varied largely between herds and between sows. The largest variation of piglet IgG was mainly on the piglet level, supporting the complex nature of IgG production and uptake. However, the strong association between colostrum IgG and piglet IgG shows that increased IgG level in colostrum will improve the levels of IgG in piglets and potentially increase survival of the piglets.

Nitrogen microbubbles induce a disappearance of single platelets (aggregation) with porcine platelets: a comparative study of the effects of anticoagulants and blood collection methods.

The pathogenesis of decompression illness (DCI) is uncertain. DCI involves all parts of the organism where gas bubbles are produced. They have both primary and secondary effects and have been classified as an agonist aggregating human platelets. In vitro effects of N2 bubbles on porcine platelets were investigated. Comparative studies using two different anticoagulants and three different sampling methods were performed. A disappearance of single platelets interpreted as platelet aggregation was observed in the presence of N2 bubbles in all studied groups. Aggregatory responses were more profound with platelets in heparinized plasma than in citrated plasma. In citrated plasma the aggregatory responses were more profound when blood was obtained from nonanaesthetized (awake) animals than from slaugtherhouse animals. Adrenaline (1 microM) had an inhibitory effect on N2 bubble induced platelet aggregation in vitro. The pig could be useful to investigate possible gas bubble effects in vivo.

Responses of plasma Epo and kidney and liver Epo mRNA to hemorrhage in perinatal pigs.

Despite the fact that pig fetuses in late gestation have extensive erythropoiesis, low blood pO(2) and low hemoglobin concentrations, piglets are born without detectable concentrations of plasma erythropoietin (Epo). In the present study, we have examined the hypothesis that long-term hypoxic stimuli are less efficient than short-term stimuli in stimulating Epo production in perinatal pigs. From fetuses collected by hysterectomy 5 days before term, new-born piglets and piglets 2 and 5 weeks old, blood in amounts corresponding to 2% of body weight was withdrawn from the jugular vein. Twenty-four hours later the animals were killed and their kidney and liver Epo mRNA analysed by a competitive RT-PCR assay. Plasma Epo concentration was estimated by a solid-phase, two-site sequential chemiluminescent enzyme immunometric assay. We found that in nearly fully developed fetuses and in new-born piglets, the concentration of Epo mRNA did not increase upon bleeding. This is in contrast to earlier findings in sheep. In 2- and 5-week-old piglets, bleeding was associated with a 12-15-fold increase in kidney Epo mRNA. In the 2- and 5-week-old piglets, bleeding evoked increased translation of Epo mRNA into the protein hormone. Also in new-born piglets, increased plasma levels of Epo accompanied bleeding, whereas significant changes in gene Epo expression were not observed.

An evaluation of iron-dextran supplementation in piglets administered by injection on the first, third or fourth day after birth.

The aims of the study were to evaluate the effect of iron-dextran injection given on the first, third or fourth day after birth on haematology in piglets. An advanced automated blood analyser; Technicon H*1, which performs a complete blood cell count and leukocyte differential counts was used to analyse the blood. Six litters of Norwegian Landrace x Yorkshire piglets were included in the study. The day after birth (day 1), half of the piglets in each litter (split litters) were injected subcutaneously with 180 mg iron as iron-dextran (1.5 ml Idofer). The untreated piglets from two of the litters were injected with the same amount of iron-dextran on day 3, and those from the remaining four litters on day 4. The piglets were weighed and blood samples collected on days 1, 3 or 4, 7, 14 and 21. Erythropoiesis, but not leukocyte count, responded to injection on day 1 compared with injection on the third or fourth day. The difference between groups in haematological parameters was greatest on day 7. The two groups of piglets treated on day 1 had a haemoglobin concentration (Hb) +/-SD of 92 g litre-1(+/-9) and 94 g litre-1(+/-9), and the piglets treated on day 3 had a Hb of 81 g litre-1(+/-7) and the one treated on day 4 had a Hb of 78 g litre-1(+/-7) on day 7. On days 14 and 21 there were no differences between groups. This study indicates that some piglets were anaemic and responded to subcutaneous iron injection on day 1.

Evaluation of thiopentone-midazolam-fentanyl anaesthesia in pigs.

Induction of anaesthesia in swine by thiopentone (27.1-35.7 mg/kg, mean 29.9 mg/kg) was followed by bolus doses and continuous infusion of midazolam and fentanyl (0.90 mg/kg followed by 0.90 mg/kg/h and 0.025 mg/kg followed by 0.025 mg/kg/h, respectively). This produced good anaesthesia and analgesia for up to 2 h in 6 Norwegian Landrace pigs (wt: 17-42 kg), based on responses to painful stimuli elicited by pinching the nasal septum, the mouth, the forefoot and the perineal skin area. The first responses occurred after 110 min of anaesthesia. No significant drop in rectal temperature due to the regimen was noted during monitoring periods (140-180 min). This combined intravenous anaesthetic regimen gave good anaesthesia and analgesia to pigs for up to 2 h as monitored by clinical signs. The regimen may not be sufficient for longer time periods. We cannot advocate the incorporation of neuromuscular blocking agents in this regimen.

A transport and monitoring unit for piglets under general anaesthesia.

A transport and monitoring unit for fully anaesthetized piglets (weight 20-30 kg) was made. The unit provided easy transport for short or longer distances while at the same time making continuous monitoring of invasive blood pressure (IBP), temperature and HR possible. The animals stayed in the unit for the duration of the experiments which required that the anaesthetized animal be kept in exactly the same position for several hours. This, as well as the experimental animal's welfare, was ensured by the unit. Such a unit can be used for any lengthy transportation of experimental animals to research facilities located separately from animal laboratories.

Ketamine and its use in the pig. Recommendations of the Consensus meeting on Ketamine Anaesthesia in Pigs, Bergen 1994. Ketamine Consensus Working Group.

Ketamine, when used as a mono-anaesthetic, does not appear to induce surgical anaesthesia in the pig. The addition of other drugs such as opioids, benzodiazepines and alpha 2-adrenergic agonists deepens anaesthesia and enables major surgery to be performed. A decision-tree for the rational use of ketamine for both short and long-term anaesthesia in the pig under three different levels of procedure severity is presented.

Anaemia in housed lambs: effects of oral iron on clinical pathology and performance.

An experiment including 39 pairs of housed twin lambs was performed to evaluate the effect of an oral iron supplement (Fe-MAX Starter) on clinical pathology, growth rates and disease occurrence. Significant differences between the iron supplemented group (Fe-group) and the controls were seen, for varying periods of time, for all red blood cell and iron parameters examined. In spite of this, 25% of the iron supplemented lambs had haemoglobin values below 80 g/L 4 weeks after treatment, whereas 33% of the controls had corresponding values 3 weeks after treatment, indicating that one single iron dose was insufficient to prevent iron deficiency anaemia. No significant positive effect on live weights was seen. However, the Fe-group had a poorer daily weight gain during the first week after dosing (p < 0.01), but a better daily gain during the second (p < 0.01) and third weeks. No effects were seen on disease occurrence. An additional trial with iron dextran injections to 5 untreated 21 days old lambs with varying haemoglobin values, revealed a rapid increase in the red cell distribution in anaemic lambs, with production of macrocytic, mainly normochromic erythrocytes. The new erythrocyte population was visible on the cytogram after 2 to 3 days and on the histogram after 5 days.

Effect of an oral starter dose of iron on haematology and weight gain in piglets having voluntary access to glutamic acid-chelated iron solution.

Six litters of Norwegian Landrace piglets were included in the study. The day after birth (day 1), half of the piglets (split litters) were given 52 mg glutamic acid-chelated Fe (4 ml of a 50% solution of Super Fe-MAX) perorally. All the piglets had free access to a 3% solution of Super Fe-MAX from this day until weaning at 5 weeks. The piglets were weighed and blood samples collected on days 1, 4, 7, 14, 21 and 35, and weighed only on days 28 and 49. The production of erythrocytes and haemoglobin was greater in the first week after birth in piglets given extra iron perorally on day 1, compared to those with voluntary access to iron. The extra peroral iron administration did not prevent some of the piglets from becoming anaemic later. Weight gain was similar in the 2 groups.

An experimental study on transcutaneous absorption of ethylesters of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in pigs.

Twenty-two pigs with an average weight of 24.2 kg were divided into two groups. Five grams of an ointment containing 40% of the n-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) as ethylesters, was administered cutaneously to the experimental group and orally to the control group twice daily over a 3 day period. Surgical biopsies of subcutaneous fat of all 22 pigs were taken before and after the ethylester administration period. Blood samples were taken from the jugular vein. Skin biopsies were taken after the application period, and the presence of pathological features and inter-animal variation were noted. No increase of EPA and DHA in subcutaneous fat was found in either group. In the oral group the content of EPA had increased in the total plasma lipids on the first day after the end of the experiment. It is concluded that a rapid transcutaneous absorption of EPA and DHA as ethylesters does not seem to occur in pigs.

Clinical biochemistry, haematology and body weight in piglets.

Reference ranges for clinical biochemical parameters commonly investigated in pigs were determined in one- (day 1), 21- and 35-day old piglets. The mean and standard deviation were also estimated for body weight, and haematological and clinical biochemical parameters at these ages. The piglets were divided into 2 investigation groups according to whether they had a haemoglobin concentration < or = 80 g/l ("anaemic group") or > 80 g/l ("normal group") on days 14, 21 and 28. The "anaemic group" was compared to the "normal group" on days 21 and 35. Many of the clinical biochemical parameters varied according to age. Some of the enzymes had high average values and wide reference ranges in piglets, especially on day 1, compared to the reference ranges for sows given in the literature. The reference ranges for some of the metabolic parameters were broader on day 1 than later in the preweaning period. The reference ranges for albumin, total iron-binding capacity and serum iron were, however, lower and more narrow on day 1. On days 21 and 35, relatively high values for phosphorus must be considered "normal" compared to the figures given in the literature for adult pigs. The other minerals seemed to be quite unaffected of age, but some were affected by anaemia. The anaemic piglets had lower average serum iron but higher total iron-binding capacity than the "normal" piglets on days 21 and 35. However, variation between piglets gave wide reference ranges, indicating that these parameters will only have limited usefulness in detecting iron deficiency anaemia in piglets. The electrolytes seemed also to be affected by the existence of anaemia. The body weight and leukocyte counts were significantly lower in the "anaemic group" than the "normal group" on day 35, while the greatest differences in clinical biochemical parameters between the groups were found on day 21, when the piglets in the "anaemic group" were most severely anaemic. Although these piglets suffered from severe iron-deficiency anaemia, only a few clinical biochemical parameters were affected, and the differences between groups were mostly small.

Effect of iron on erythropoietin production in anaemic piglets.

In the present study the response of plasma erythropoietin to iron injection in anaemic piglets was examined. At the age of 16 days, 4 piglets from the same litter were given 180 mg iron subcutaneously. After iron injection, blood samples for estimation of erythropoietin activity in plasma, haemoglobin concentration, and reticulocyte counts were taken every 6 or 12 h for 3 1/2 days. Plasma erythropoietin activity was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human erythropoietin. On the day of iron injection, haemoglobin concentration ranged between 41 and 48 g/l, reticulocyte counts from 9 to 17 percent, and plasma erythropoietin between 22 and 144 mU/ml. In 3 of the 4 piglets, iron injection resulted in a 2-6 fold increase in erythropoietin activity. Maximal erythropoietin activities were observed 24-42 h after injection, and after 66 h, the activities were close to the pretreatment values. It is concluded that in our experiment, iron, per se, has stimulated erythropoietin production.

The effect of peroral administration of amino acid-chelated iron to pregnant sows in preventing sow and piglet anaemia.

Two trials were performed in 2 different pig herds. In Trial 1, 9 pregnant Norwegian landrace sows were given a supplement in the feed of about 300 mg iron daily as amino acid-chelated iron (Bio-plex) during the last 3 weeks of gestation. Ten sows were included as controls. In Trial 2, 10 sows were fed a supplement of about 650 mg iron daily as glutamic acid-chelated iron (Super Fe-MAX) during the same period of pregnancy as in Trial 1. Twenty-two sows were included as controls. Blood samples were taken from the sows at the start of the experiment and on the day after parturition. The sows in Trial 1 were also bled at weaning 5 weeks after parturition. The piglets were weighted and blood samples collected 24 +/- 12 h after birth. Livers were taken from 65 piglets, which were either still-born or which died or were euthanised as one-day olds, and examined for iron content. The erythrocyte count (RBC), haemoglobin concentration (HGB), mean cell volume (MCV), erythrocyte distribution width (RDW), and haemoglobin distribution width (HDW) in blood were measured. Haematocrit (HCT), mean cell haemoglobin (MCH), and mean cell haemoglobin concentration (MCHC) were also estimated. Blood serum was analysed for total proteins, albumin, serum Fe, and total iron-binding capacity (TIBC). A slight increase in HGB and RBC in the piglets from the iron-treated sows compared with the controls was found in Trial 1, but this was considered to be of no practical importance. None of the other measured parameters were influenced by treating the pregnant sows with amino acid-chelated iron.

Plasma erythropoietin in newborn lambs.

In the present study early postnatal changes in erythropoietin (Epo) level and hemoglobin concentration in 8 lambs were examined. Plasma Epo was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human Epo. In all the lambs, except one, Epo was low, or undetectable, immediately after birth. Within 6-12 h after birth, a marked increase in plasma Epo was found in 4 of the lambs. Within 3-7 days after birth, Epo was back to low levels. In the lamb with high Epo levels at birth, drastic decreases were observed during the next 6 h. There was no obvious correlation between the hemoglobin concentrations and the changes in plasma Epo.