Analysis of tissue from products of conception and perinatal losses using QF-PCR and microarray: A three-year retrospective study resulting in an efficient protocol

OBJECTIVE

To evaluate the performance of a laboratory protocol for direct genetic analysis performed on tissues obtained from miscarriages, stillbirth and postnatal death.

METHODS

Samples were collected between July 1st, 2011 and June 30th, 2014. QF-PCR analysis was the initial test followed by aCGH analysis performed on the normal QF-PCR specimens.

RESULTS

Of the 1195 submitted specimens, a total of 1071 samples were confirmed as true fetal. The failure rate was 1.4%. Of those, 30.8% yielded abnormal results. Of the latter, 57.6% had abnormal QF-PCR and 42.4% had abnormal microarray result. Autosomal trisomies were detected in 61.2%, triploidy in 7.6%, monosomy X in 9.1%, sex-chromosome aneuploidy (apart from monosomy X) in 1.5%, molar pregnancies in 5.8% and copy number variants in 14.2% including microdeletions/microduplications and cryptic unbalanced rearrangements. The highest diagnostic yield was observed in the 1st trimester specimens at 67.6%. We confirmed that maternal age correlates with the likelihood of autosomal trisomies but not with triploidy, sex chromosome aneuploidies, molar pregnancy, or CNVs.

CONCLUSION

An efficient laboratory protocol, based on QF-PCR and aCGH of uncultured cells has replaced standard cytogenetic analysis in testing of tissue from all pregnancy losses in our center and resulted in reduced test failure rate and increased diagnostic yield.

Performance of growing-finishing pigs fed diets containing YieldGard Rootworm corn (MON 863), a nontransgenic genetically similar corn, or conventional corn hybrids

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either YieldGard Rootworm corn (MON 863), a non-transgenic genetically similar corn (RX670), or two conventional nontransgenic corn hybrids (DK647 and RX740). A randomized complete block design with a 2 x 4 factorial arrangement of treatments (two genders and four corn hybrids) was used. Study 1 used 72 barrows and 72 gilts (progeny of Danbred sires x [Danbred x NE White line] dams grown from 22.7 to 117.0 kg BW). Pigs were housed in a modified open-front building in single-gender groups of six (six pens per dietary treatment). Study 2 used 80 barrows and 80 gilts (progeny of PIC 337 sires x C22 dams) grown from 29.5 to 114.9 kg BW. Pigs were housed in an environmentally controlled finishing building in single-gender groups of five (eight pens per dietary treatment). The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered at the end of the growth period using standard procedures, and carcass measurements were taken. There were no diet x gender interactions for growth performance or carcass measurements in either study. In both studies, overall ADG, ADFI, and G:F were not affected by corn hybrid. There was no effect of corn hybrid on carcass or LM quality measurements in Study 1. In Study 2, LM protein content was less (P< 0.05) for pigs fed RX740 compared with those fed either MON 863 or RX670; however, there was no effect of corn hybrid on other LM composition measures or on quality traits. In both studies, differences between barrows and gilts for growth and carcass traits were similar to previous research. These results suggest that the YieldGard Rootworm corn (MON 863) results in equivalent growth performance and carcass quality to nontransgenic corn hybrids in growing-finishing pigs.

Effect of dietary leucine and lysine levels on intramuscular fat content in finishing pigs

Feeding high leucine levels (2.0 and 3.0% total dietary leucine) to finishing pigs (73 to 127 kg liveweight) increased the intra muscular fat content of the longissimus muscle in pigs fed diets with low lysine levels (0.5% total dietary lysine) but not in animals fed high lysine levels (0.7 %). Key words: Lysine, leucine, growth performance, carcass and meat quality

Performance of growing-finishing pigs fed diets containing Roundup Ready corn (event nk603), a nontransgenic genetically similar corn, or conventional corn lines

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either glyphosate-tolerant Roundup Ready (event nk603) corn, a nontransgenic genetically similar control corn (RX670), or two conventional sources of nontransgenic corn (RX740 and DK647). A randomized complete block design (three and four blocks in Studies 1 and 2, respectively) with a 2 x 4 factorial arrangement of treatments (two genders and four corn lines) was used. Study 1 used 72 barrows and 72 gilts (housed in single-gender groups of six; six pens per dietary treatment) with initial and final BW of approximately 22 and 116 kg, respectively. Study 2 used 80 barrows and 80 gilts (housed in single-gender groups of five; eight pens per dietary treatment) with initial and final BW of approximately 30 and 120 kg, respectively. Pigs were housed in a modified open-front building in Study 1 and in an environmentally controlled finishing building in Study 2. The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered using standard procedures and carcass measurements were taken. In Study 1, overall ADG, ADFI (as-fed basis), and gain:feed (G:F) were not affected (P > 0.05) by corn line. In Study 2, there was no effect of corn line on overall ADFI (as-fed basis) or G:F ratio. In addition, overall ADG of barrows fed the four corn lines did not differ (P > 0.05); however, overall ADG of gilts fed corn DK647 was greater (P < 0.05) than that of pigs fed the other corn lines. There was no effect (P > 0.05) of corn line on carcass yield or fatness measurements in either study. Differences between barrows and gilts for growth and carcass traits were generally similar for both studies and in line with previous research. Overall, these results indicate that Roundup Ready corn (nk603) gives equivalent animal performance to conventional corn for growing pigs.

Comparison of broiler performance when fed diets containing grain from YieldGard Rootworm (MON863), YieldGard Plus (MON810 × MON863), nontransgenic control, or commercial reference corn hybrids

Two 42-d experiments compared the nutritional value of YieldGard Rootworm corn (MON863; experiment 1) and YieldGard Plus corn (MON810 x MON863; experiment 2) to their respective nontransgenic controls and 6 commercial reference corn hybrids when fed to growing broilers. For each experiment, a randomized complete block design was used with 8 dietary treatments in each of 5 replicated blocks of pens. In experiment 1, no differences among diets were observed (P > 0.05) for final live weights and feed conversion. Broilers fed diets containing MON863 corn had adjusted feed conversion similar to the nontransgenic control and the population of control and commercial diets. On a weight basis, there were no differences among diets for chill, fat pad, and thigh, drum, and wing weights. Differences (P < 0.05) between MON863 and commercial corn diets were noted for breast meat, chill and thigh, drum, and wing weights on a percentage of weight basis. No differences were observed (P > 0.05) in the percentage of moisture, protein, and fat in breast meat or thigh meat across treatment diets. In experiment 2, there were no significant differences among diets for all broiler performance and carcass parameters evaluated. Broilers overall performed consistently and had similar carcass yields and meat compositions when fed diets containing MON863 corn or MON810 x MON863 corn as compared with their respective nontransgenic control and commercial diets, supporting a conclusion of similar feeding values among diets.

Effect of dietary leucine level on growth performance, and carcass and meat quality in finishing pigs

The effect of feeding corn-soybean meal-based diets with two levels of supplemental leucine (0 vs. 2%) on growth, carcass, and pork quality characteristics was evaluated in 40 individually fed finishing pigs over a 39-d feeding period (78.4 ± 3.46 to 114.8 ± 7.30 kg liveweight). Supplemental dietary leucine reduced weight gain (8.7%; P < 0.05), but had no effect (P > 0.05) on feed intake or gain:feed ratio. Feeding diets with 2% supplemental leucine increased (P < 0.05) longissimus fat content and marbling scores in both barrows and gilts. Key words: Finishing pigs, dietary leucine, intramuscular fat

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.

Pharmacokinetics and pharmacodynamics of serum platinum of gynecologic cancer patients treated with nedaplatin

Nedaplatin (cis-diammine glycolate platinum) is one of the effective platinum agents for gynecologic carcinoma. In order to assess the pharmacokinetics and pharmacodynamics of serum platinum of gynecologic cancer patients treated with nedaplatin, we calculated 10 course AUCs (area under the curve) of the free and total platinum from blood samples of 4 patients. Peak serum platinum concentrations were dependent on infusion times. In the case of a patient with renal dysfunction or ascites, the concentration of serum platinum tended to stay at a high level for a long time. Serum-free platinum ratios were maintained longer than cisplatin. Low dose nedaplatin administration and divided administration were effective, but total AUC was not so great. The relation between AUC ratio (free platinum AUC/total platinum AUC) and dose/m(2) was not clarified.

Expression of cyclooxygenase-2 in ovarian mature cystic teratomas with malignant transformation

Cyclooxygenase-2 (COX-2) has been reported to be associated with tumor progression and angiogenesis and we previously reported that an increase in COX-2 expression might be associated with malignant transformation and tumorigenesis of epithelial ovarian neoplasms. In this study, COX-2 expression of ovarian mature cystic teratomas with malignant transformation, a rare entity accounting for just 1.8% of all mature cystic teratomas, was investigated using immunohistochemical techniques. There were 89 cases of mature cystic teratomas treated with surgery as their initial therapy at Osaka City University Medical School Hospital between 1995 and 2001. Ten cases of these were selected for study; five cases of mature cystic teratoma with malignant transformation, and five cases of mature benign teratoma. Expressions of CD34, vascular endothelial growth factor (VEGF), and COX-2 were investigated. Expressions of VEGF and COX-2 were strong in tissues of mature cystic teratomas with squamous cell carcinoma; however, expressions of them were hardly apparent in mature benign teratomas and in mature cystic teratomas with adenocarcinomas. These results tend to suggest that COX-2 is associated with tumor growth and progression in mature cystic teratomas with squamous cell carcinoma, as opposed to mature benign teratomas and mature cystic teratomas with adenocarcinomas.

Comparison of expression of apoptosis regulatory proteins in the adipose tissue of tumor-bearing and diet-restricted rabbits

We investigated the expression of apoptosis regulatory proteins in the adipose tissue of tumor-bearing and diet-restricted rabbits, and analyzed the differences between the two groups. The apoptotic index in the tumor-bearing group was 25.1+/-12.4 on day 10 and increased to 27.2+/-14.4 by day 20. Thereafter, however, it gradually decreased, falling to 11.2+/-7.8 on day 30 and 0.67+/-0.88 on day 40. By contrast, no apoptotic cells were detected in the diet-restricted group at any of the times examined. Bcl-2 immunoreactivity was either not detected at all, or was only weakly observed in both groups. Bax expression, on the other hand, gradually increased after implantation in the tumor-bearing group. In 2 of the 5 tumor-bearing rabbits, Bax expression in adipocytes was moderate 10 days after tumor implantation, and strong by day 20, but steadily decreased thereafter. By contrast, hardly any Bax-immunopositive cells were detected in the diet-restricted group. These results suggested that loss of body weight in the tumor-bearing group was different from that in the diet-restricted group, and that it was related to adipocyte apoptosis.

Involvement of angiogenesis in weight-loss in tumor-bearing and diet-restricted animals

The body's weight loss mechanism while in a tumor-bearing state is still unclear. In this study, we investigated expressions of angiogenic factors in the adipose tissue of tumor-bearing and diet-restricted rabbits evaluating the differences between the two groups. We postulated that low nutrition induced vasculogenesis to transport nutrition in the adipose tissues of diet-restricted rabbits, unlike in tumor-bearing rabbits, and that vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) were related to angiogenesis of the adipose tissues. Although we investigated the expressions of VEGF and PD-ECGF immunohistochemically in tumor-bearing and diet-restricted rabbits, there was no significant difference between the two groups. Whether angiogenesis of the adipose tissue in the diet-restricted animals may be observed during the nutritional recovery period should be investigated.

Probucol decreases total body fat loss in VX2-carcinoma-induced cachectic rabbits

We previously reported the continuous decrease of total body fat in VX2-carcinoma-bearing rabbits after tumor implantation, as well as changes in the serum lipid profile. Probucol, an antioxidant drug, has a cholesterol lowering effect against hyperlipidemic subjects. VX2-carcinoma-bearing rabbits fed with a diet containing 1% probucol did not show any difference in serum lipid compositions as compared with rabbits fed with a control diet. Similarly serum lipolytic activity showed no differences, whether probucol was administered or not, while the decrease in total body fat was significantly less when probucol was administered.

Angiogenesis in the adipose tissue of tumor-bearing rabbits treated by cyclic plasma perfusion

The mechanisms of cancer cachexia have not been elucidated. We previously reported that cyclic plasma perfusion using non-coated charcoal was effective in cancer cachexia. In the present study we investigated the angiogenic effect of cyclic plasma perfusion on adipose tissue. Twenty rabbits were divided into two groups, i.e., tumor-bearing rabbits subjected to cyclic plasma perfusion (n=10, PP group), and tumor-bearing rabbits subjected to sham-perfusion (n=10, SP group). The changes in body weight, total body fat, and expression of angiogenic factors were investigated. Loss of body weight and total body fat was significantly suppressed in the PP group. Apoptosis of adipocytes was seen in both groups only in the early stage of tumor bearing. Lipolytic activity in the PP group showed a lower ratio than that in the SP group. In the PP group, increased microvessel density and expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) were seen at 40 days after transplantation. Similar findings were not seen in the SP group. These results suggest that cyclic plasma perfusion not only decreased lipolytic activity but induced angiogenesis in the adipose tissue.

Conservative management of placental polyp with oral administration of methotrexate

Surgical treatment is usually selected for placental polyp accompanied by massive bleeding but patients wishing to conserve their fecundity require conservative management. A 35-year old nullipara was diagnosed as having placental polyp on the basis of typical episodes, and detection of placental polypeptide hormones and blood flow by Doppler ultrasonography and dynamic magnetic resonance imaging. Oral administration of methotrexate (2.5 mg, three times a day for 5 days) was repeated for three cycles because surgical treatment was rejected. Serum human placental lactogen, blood flow and the polyp disappeared sequentially following chemotherapy. This report thus advocates considering conservative management for placental polyp.

Expression of apoptosis regulatory proteins in the skeletal muscle of tumor-bearing rabbits compared with diet-restricted rabbits

The mechanism of body weight loss in the tumor-bearing state is still unclear. In this study, we investigated expressions of apoptosis regulatory proteins in the skeletal muscle of tumor-bearing and diet-restricted rabbits, and tried to evaluate the differences between the two groups. The apoptotic index (AI) in the tumor-bearing group was 28.1+/-2.84 on day 10. By day 20, many more apoptotic cells were found (AI: 40.5+/-3.20), but then after day 20 their numbers gradually decreased (AI: 9.67+/-2.22 on day 30 and 0.93+/-0.96 on day 40). By contrast, no apoptotic cells were detected in the diet-restricted group at any of the times examined. Bcl-2 immunoreactivity was either not detected at all or only weakly observed in both groups. By contrast, Bax expression increased gradually after implantation in the tumor-bearing group. Bax expression in skeletal muscle cell was graded (moderate) 10 days after tumor implantation, and (high) by day 20, in 2 of the 5 tumor-bearing rabbits. After day 20, however, Bax immunoreactivity decreased continuously in the tumor-bearing group. By contrast, hardly any Bax-immuno-positive cells were detected in the diet-restricted group. These results suggest that loss of body weight in the tumor-bearing group is different from that in the diet-restricted group, and is related to apoptosis of skeletal muscles.

Effect of cyclic plasma perfusion on apoptosis regulatory proteins in primary tumors of VX2-carcinoma-bearing rabbits

Although the mechanism of cancer cachexia is unknown, in previous studies we reported that cyclic plasma perfusion through non-coated charcoal was effective in preventing cancer cachexia. In the present study we investigated the effect of cyclic plasma perfusion on VX2 carcinoma. Sixteen tumor-bearing rabbits were divided into two groups: i) a group subjected to cyclic plasma perfusion (n=8, group PP) and ii) a group subjected to sham-perfusion (n=8, group SP), and changes in body weight, tumor size, and morphological findings were investigated. Body weight loss and tumor growth were significantly suppressed in group PP. The tumor cells in group PP showed apoptosis and a high Bax/Bcl-2 ratio, and the survival rate was significantly higher than in group SP. These results suggest that cyclic plasma perfusion is effective not only in preventing cancer cachexia but in suppressing tumor growth and improving outcome.

Expression of skeletal muscle cells apoptosis regulatory proteins in plasma-perfused VX2 carcinoma-bearing rabbits

BACKGROUND

In tumor-bearing animals we found that the skeletal muscle apoptosis might be involved in muscle wasting. In this study, we investigated changes in the skeletal muscle cell apoptosis regulatory proteins after cyclic plasma-perfusion (CPP).

MATERIALS AND METHODS

We studied changes in body weight, lean body mass (LBM), apoptotic index (AI) and expression of Bax and Bcl-2 in skeletal muscle in VX2 carcinoma-bearing rabbits.

RESULTS

20 days after tumor implantation, LBM had decreased by 5.06+/-1.10%, while the AI had increased to 40.5+/-3.20%. By 40 days, LBM had decreased by 11.0+/-0.81% and the AI was only 0.93+/-0.96%. Bax expression was detected in proportion to the AI, but no Bcl-2 expression was detected in either the experimental or control groups. CPP improved LBM, but did not prevent Bax expression.

CONCLUSION

Skeletal muscle cell apoptosis related to Bax was concluded to be the cause of muscle wasting in VX2 carcinoma-bearing rabbits. CPP appears to reduce muscle wasting and increase LBM, but it did not suppress Bax expression or skeletal muscle cell apoptosis.

Effect of group size and feeder type on growth performance and feeding patterns in growing pigs

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in growing pigs over a 4-wk period. A total of 416 hybrid pigs (barrows and gilts) were grown from 26.5 (SD = 1.6) to 47.8 (SD = 2.7) kg BW and given ad libitum access to a corn-soybean meal-based diet (17.4% CP; 0.9% lysine; 3,298 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Pigs using the electronic feeders had similar growth rates but lower feed intakes (P < 0.01) and higher gain:feed ratios (P < 0.01) compared to those using the conventional feeders. Barrows compared to gilts had higher growth rates (P < 0.05), numerically higher (P > 0.05) ADFI, and similar feed efficiency and feeding pattern. Feed intakes and growth rates were lowest (P < 0.05) for groups of 12 pigs but gain:feed ratio was not affected by group size. Daily feeder occupation time per pig was lower (P < 0.01) for groups of 12 than for groups of 2 or 4 pigs, and feed consumption rate was higher (P < 0.01) for groups of 12 than for groups of 4 pigs. The proportion of time spent eating was lower (P < 0.01) and the proportion of time spent standing was higher (P < 0.01) for pigs in groups of 12 compared to groups of 2. Correlations between ADG and ADFI and feed intake per visit were 0.29 and 0.30, respectively (P < 0.01), between ADG and ADFI and feed consumption rate were 0.27 and 0.31, respectively (P < 0.01), and between ADFI and feeder occupation time per day were 0.33 (P < 0.01). This study suggests that, in growing pigs given access to a single feeder, changes in feeding behavior with increasing group size were not sufficient to maintain feed intake and growth rate.

Different uptake of 99mTc-ECD adn 99mTc-HMPAO in the same brains: analysis by statistical parametric mapping

The purpose of this study was to investigate the differences between technetium-99m ethyl cysteinate dimer (99mTc-ECD) and technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) uptake in the same brains by means of statistical parametric mapping (SPM) analysis. We examined 20 patients (9 male, 11 female, mean age 62+/-12 years) using 99mTc-ECD and 99mTc-HMPAO single-photon emission tomography (SPET) and magnetic resonance imaging (MRI) of the brain less than 7 days after onset of stroke. MRI showed no cortical infarctions. Infarctions in the pons (6 patients) and medulla (1), ischaemic periventricular white matter lesions (13) and lacunar infarction (7) were found on MRI. Split-dose and sequential SPET techniques were used for 99mTc-ECD and 99mTc-HMPAO brain SPET, without repositioning of the patient. All of the SPET images were spatially transformed to standard space, smoothed and globally normalized. The differences between the 99mTc-ECD and 99mTc-HMPAO SPET images were statistically analysed using statistical parametric mapping (SPM) 96 software. The difference between two groups was considered significant at a threshold of uncorrected P values less than 0.01. Visual analysis showed no hypoperfused areas on either 99mTc-ECD or 99mTc-HMPAO SPET images. SPM analysis revealed significantly different uptake of 99mTc-ECD and 99mTc-HMPAO in the same brains. On the 99mTc-ECD SPET images, relatively higher uptake was observed in the frontal, parietal and occipital lobes, in the left superior temporal lobe and in the superior region of the cerebellum. On the 99mTc-HMPAO SPET images, relatively higher uptake was observed in the medial temporal lobes, thalami, periventricular white matter and brain stem. These differences in uptake of the two tracers in the same brains on SPM analysis suggest that interpretation of cerebral perfusion is possible using SPET with 99mTc-ECD and 99mTc-HMPAO.

New cervicoscopy with toluidine blue staining for superficial cervical invasion by endometrial carcinoma

We developed a method of endocervical staining with toluidine blue solution during cervicoscopy that clearly discriminates between the endocervical region and the endometrium and allows easy detection of superficial cervical invasion by endometrial carcinoma. Toluidine blue staining cervicoscopy was used for preoperative histological diagnosis in 10 cases of endometrial carcinoma. The staining permitted a correct diagnosis in 3 cases in which conventional diagnostic methods were practically useless. Endocervical staining with toluidine blue is highly useful for diagnosis of superficial cervical invasion by endometrial carcinoma.

Effects of feeder type, space allowance, and mixing on the growth performance and feed intake pattern of growing pigs

The effect of crowding and mixing on growth performance and feed intake pattern were investigated in growing pigs in a 4-wk study. Feeding pattern was monitored using automated feed intake recording equipment (F.I.R.E.). A total of 256 Yorkshire x Hampshire and purebred Duroc pigs (initial weight 35.8+/-.86 kg) were allocated to one of the eight treatment combinations in a 2x2x2 factorial arrangement (feeder type [conventional feeder vs F.I.R.E. feeder], space allowance [.56 vs .25 m2/pig], and mixing strategy [mixed vs unmixed; mixing at start of wk 1 and 3]). Pigs were housed in groups of eight, balanced for genotype and sex (barrows and gilts), and had free access to a corn-soybean meal diet (17% crude protein, 3,296 kcal ME/kg). There was no difference in growth performance between feeder types. Crowding and mixing had no effect on daily feed intake but they depressed growth rate by 15.7 and 7.1%, respectively, and the effects of the two stressors were additive. Gain:feed ratio was reduced by crowding (10.0%) but not by mixing. Crowded pigs made fewer (11.2 vs 15.7; SEM = .51), and longer (12.5 vs 8.9 min; SEM .41) feeder visits and had higher feed intake per visit (196.2 vs 145.5 g; SEM = 5.94) than uncrowded animals. Mixing produced changes in feeding pattern in the 1st wk after mixing but not over the 4-wk period. This study showed that crowding and mixing depressed growth rates in an additive manner and altered feeding behavior.

Growth performance of pigs subjected to multiple concurrent environmental stressors

The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire x Hampshire or purebred Duroc pigs (34.7+/-.5 kg) were subjected to one of the eight treatment combinations (2 x 2 x 2 factorial) of ambient temperature (constant thermoneutral [24 degrees C] or high cycling temperature [28 to 34 degrees C]), stocking density (.56 or .25 m2/pig), and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The temperature regimens were imposed in two adjacent mechanically ventilated rooms, and each temperature was imposed in each room across two trials. Four barrows and four gilts were assigned to each of the eight pens in the two rooms, and they always had free access to water and a corn-soybean meal-based diet. Treatments were imposed after a 7-d acclimation period at 24 degrees C and .56 m2/pig. Weight gain and feed intake were measured weekly. The main effects of each of the stressors for 4-wk ADG and ADFI were significant (P < .05). The stress of high temperature, high stocking density, and regrouping depressed 4-wk ADG by 12, 16 and 10% and ADFI by 7, 6, and 5%, respectively. Of the possible 60 stressor interactions for ADG, ADFI, and gain:feed (G:F), there were no significant three-way interactions and only six two-way interactions, suggesting that the effects of the individual stressors were additive. Accordingly, the growth rate of pigs subjected to the single stressor of high cycling temperature, restricted space allowance, or regrouping was depressed 10, 16, and 11%, respectively, and ADG of pigs subjected to all three stressors simultaneously was depressed by 31%. Stressor additivity was further corroborated by examining the effect of stressor order, or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI, and G:F decreased linearly. These data suggest that multiple concurrent stressors affect growth performance of pigs in a predictable fashion (i.e., additively) and indicate that avoidance or removal of a given stressor is advantageous even when other uncontrollable stressors persist.

Feed intake pattern of group-housed growing-finishing pigs monitored using a computerized feed intake recording system

The feed intake pattern and growth performance of boars, barrows, and gilts fed diets differing in lysine and protein content were measured on 120 crossbred pigs from 27 (SD 3.7) to 81.5 (SD 9.2) kg live weight. The pigs were housed in eight mixed-sex groups with five pigs of each sex in each group. They were fed from an electronic feed station that recorded individual meal sizes and the time and duration of visits to the feeder for each animal in the group. Four dietary treatments were compared. During the grower period (27 to 55 kg), diets ranged in lysine content form .98 to 1.31%; for the remainder of the study, lysine content was .88 to 1.18%. Barrows had a greater (P < .01) number of meals per day than the other two sexes (7.4 vs 7.0 vs 7.0 +/- .10, respectively), but there were no significant differences among sexes for daily feed intake or other feed intake traits. Daily feed intake increased with dietary lysine content, largely because of increased meal sizes resulting from longer feeder occupation times at each visit. Visits to the feeder were greatest between 0900 and 1100 and lowest between 2000 and 0400. Correlations between feeding pattern and growth traits were relatively low. Repeatabilities of feeding pattern traits were generally higher when measured over shorter time periods. These results suggest a change in feeding behavior with increasing dietary lysine levels and a relatively small effect of sex on feeding pattern for mixed-sex groups of 15 pigs fed from a single electronic feed station.