苜蓿黄酮对雌性大鼠生长和繁殖性能的影响

为了研究苜蓿黄酮对大鼠生长、繁殖及内分泌系统的影响,本实验设计了3个苜蓿黄酮剂量组(120,400,1 200 mg/kg)和2个对照组(己烯雌酚0.5 mg/kg、空白对照组)。通过化学发光法对大鼠雌二醇(E2)、催乳素(PRL)、孕酮(P)、生长激素(GH)检测,并对大鼠繁殖相关的指标,包括子宫湿重/系数、卵巢湿重/系数、采食量、日增重、产仔数、初生窝重进行测定。结果显示,低剂量的苜蓿黄酮显著提高了性成熟雌鼠的E2水平以及子宫湿重/系数(P<0.05),显著降低了卵巢湿重/系数(P<0.05)。对未性成熟雌鼠,苜蓿黄酮对激素的影响不显著,但中、低剂量组显著降低了子宫湿重(P<0.05)。此外,苜蓿黄酮和对照组比,在采食量上不存在显著差异,但性成熟大鼠的产仔数和初生窝重有提高的趋势,中、高剂量组的产仔数和空白对照比,分别提高0.4%和2.2%。中、高剂量组的初生窝重和空白对照比,分别提高5.14%和0.10%,但差异性并不显著(P>0.05)。配种前灌胃不同剂量的苜蓿黄酮在一定程度上影响了性成熟和未性成熟雌鼠的激素分泌和生殖器官的发育, 但未能明显改善雌鼠的繁殖性能。     

Synchronisation of lambing with low doses of dexamethasone in Chios ewes--short communication

The purpose of the present study was to investigate the feasibility of improving the synchronisation of lambing after oestrus synchronisation and artificial insemination (AI). To this end, low doses of dexamethasone 21-isonicotinate (DEX) alone or in combination with prostaglandin F2a (PG) were used in five treated groups (n = 20 each) and one control group (n = 136) of Chios ewes. On day 143 of pregnancy 1.5 mg DEX was given in Group 5, while on day 146 the following treatments were applied: 0.0375 mg PG in Groups 4 and 5, and 1, 1.5 and 2 mg of DEX in ewes of Groups 1, 2 and 3, respectively. The control ewes received no treatment. The 1.5 and 2 mg dose of DEX was more effective in synchronising labour as regards the treatment to lambing interval and the proportion of ewes that gave birth within 3 days. However, obstetrical manipulations were needed, and dead lambs were born when 2 mg DEX was used. It was concluded that lambing can be safely synchronised in Chios ewes with 1.5 mg DEX given on day 146, without affecting the viability of lambs and without parturition complications.     

The regression of unsuckled mammary glands during lactation in sows: the influence of lactation stage, dietary nutrients, and litter size.

During lactation in the sow, mammary glands that are not regularly suckled undergo regression. This study characterizes the regression of unsuckled mammary glands and how that regression is affected by dietary nutrients and litter size. Sixty-nine primiparous sows were fed one of four diets containing combinations of two protein levels (32 or 65 g lysine/d) and two energy levels (12 or 17.5 Mcal ME/d) during lactation. Litter size was adjusted to 10. Sows were killed on d 0, 5, 10, 14, 21, or 28 of lactation. In another experiment, twenty-eight primiparous sows were allotted to have different litter sizes and were killed on d 21 of lactation. The day before slaughter, teat order of each litter was observed. After death, mammary glands were removed and dissected. Skin and extraneous fat pads were removed from the mammary glands and individual glands were separated. Each gland was weighed, cut in half to measure cross-sectional area, and ground for chemical analysis. The amounts of dry tissue, protein, fat, ash, and DNA were measured. Only glands observed to be unsuckled were included in the results. Regression of unsuckled mammary glands occurred rapidly during the first 7 to 10 d of lactation, as indicated by a decline in wet weight, dry weight, protein, fat, DNA, and cross-sectional area. The rate of regression was slowed after the early lactation period. The rate of regression of unsuckled glands was affected by dietary nutrient levels. Dietary energy level affected (P < 0.05) the decline in wet and dry weights, protein, fat and DNA content, and cross-sectional area, whereas dietary protein level affected (P < 0.05) the decline in dry weight and fat content. At d 5 of lactation, the wet weight of unsuckled mammary glands in sows fed the high-energy high-protein diet was 91% greater (P < 0.05) than in sows fed the low-energy low-protein diet. Effects of litter size on size and composition of unsuckled glands were not significant by d 21 of lactation. Unsuckled mammary glands regress rapidly during early lactation, and the rate of regression is affected by dietary nutrient intake.     

Mammary gland growth as influenced by litter size in lactating sows: impact on lysine requirement

Twenty-eight primiparous sows were used to determine the effect of litter size on the growth of mammary glands and nursing pigs during lactation. Litter size was set to 6, 7, 8, 9, 10, 11, or 12 pigs by cross-fostering immediately after birth. Four sows were allotted to each litter-size group. Sows were allowed to consume a daily maximum of 13.6 Mcal ME and 46.3 g of lysine during lactation. Sows were slaughtered on d 21 (20.6+/-1.1) of lactation. Mammary glands were collected at slaughter and trimmed of skin and the extraneous fat pad. Each gland was separated, weighed, and ground for chemical analysis. Dry matter, dry fat-free tissue (DFFT), crude protein, ash, and DNA contents were measured. Only glands known to have been nursed were included in the data set. Wet and dry weights and the amounts of DFFT, protein, DNA, ash, and fat in individual nursed mammary glands linearly decreased (P<.05) as litter size increased. Percentages of DFFT, protein, and DNA were quadratically affected (P<.05) by litter size on d 21 of lactation. Total mammary wet and dry weights and total DFFT, protein, DNA, fat, and ash amount of all nursed mammary glands of each sow were increased as litter size increased (P<.05). Changing litter size from 6 to 12 pigs resulted in 2,098, 432, 253, 227, 4.4, 178, and 20 g increases in the amounts of total mammary wet weight, dry weight, DFFT, protein, DNA, fat, and ash, respectively, on d 21 of lactation. Litter weight gain was 18.1 kg greater in sows with 12 pigs than in sows with 6 pigs. Sows with a larger litter size had a greater increase in total mass of mammary gland tissue and litter weight but had lower growth of individual nursed mammary glands and individual pigs than sows with the smaller litter size. The need for nutrients to support additional mammary gland and litter growth as litter size increases should be considered when estimating nutrient requirements for lactating sows. Sows need an additional .96 g lysine per day to account for mammary gland growth for each pig added to a litter.     

Growth of nursing pigs related to the characteristics of nursed mammary glands

The purpose of this study was to determine growth performance of nursing pigs in relationship to teat order and to observe teat preference by pigs. In the first experiment, litter size of 13 primiparous sows was adjusted to 9 (8.7 +/- 1.5) pigs and teat order of each litter was observed on the day before slaughter. Another group of eight sows was killed on d 0 (within 12 h after farrowing). In the second experiment, litter size was adjusted to 9 (8.9 +/- 1.4) pigs for 20 primiparous sows and teat order for each litter was observed 1 d before slaughter. The weights of sows and individual pigs were recorded at farrowing, weekly, and on the day before slaughter. Mammary glands were collected at slaughter on d 21 of lactation and trimmed of skin and the extraneous fat pad. Individual glands were separated, weighed, and ground for measurement of dry matter, dry fat-free tissue, protein, fat, ash, and DNA contents. Middle mammary glands had the greatest wet weight among glands obtained within 12 h after weaning (P < .05). For sows completing the 21 d lactation, only glands known to have been nursed were included in the data sets. Greater than 60% of the first four pairs of mammary glands were nursed, and less than 40% of the seventh and eighth glands were nursed by pigs during lactation. Pigs that nursed the first five pairs of anterior glands gained faster than pigs nursing the remaining glands. The first five pairs of anterior glands had greater wet and dry weights, and greater protein and DNA contents compared with the remaining glands. Pigs that nursed heavier glands gained weight faster (r = .68, P = .0001), and those heavier glands contained greater amounts of protein (r = .98, P = .0001) and DNA (r = .66, P = .0001). Variation in weight gain of pigs nursing the anterior and middle glands was not statistically significant. The functional superiority of anterior and middle glands was positively correlated with body weight gain of nursing pigs.     

Effect of dietary fibre on reproductive performance of sows during the first two parities

The aim of this study was to investigate the effect of dietary fibre on reproductive performance during the first two parities. Gilts were randomly allocated to receive three fibrous diets from days 1-90 of gestation, including low fibre [low fiber (LF), 10.8% neutral detergent fiber (NDF), n=132], middle fibre [middle fiber (MF), 15.8% NDF, n=132] and high fibre diet (HF, 20.8% NDF, n=135), until completion of the second parity. Response criteria included backfat measurements, litter size and pig weight at parturition and day 22 of lactation, weaning-oestrus-interval, oestrus rate, sow farrowing and culling rate, uniformity of newborns and relative organ weights. The results showed sows fed LF diet in parity 1 gained more backfat (p<0.05) during gestation but lost more (p<0.05) during lactation than sows fed HF diet. Furthermore, sows fed LF diet farrowed more pigs (+0.7-1.1 pigs, p<0.05) and pigs born alive (+1.0 pigs, p<0.05) relative to sows fed HF diet. Likewise, sows fed LF and MF diets had greater litter weights at parturition (both p=0.06) and day 22 after lactation (both p<0.05). In parity 2, yet, it was MF diet to increase both total pigs born and pigs born alive (+0.9-1.1 pigs, p<0.05) and litter weight (p=0.05) relative to other diets. After 22 d of lactation, intriguingly, sows fed HF diet had most pigs alive (p<0.01-0.07) and heavier litter weight (p=0.07 or 0.2). Feeding HF diet also increased internal organs weight of newborns (p<0.05). Collectively, feeding LF and MF diets had beneficial effects on litter weight at parturition and day 22 of lactation in parity 1, and feeding MF diet until parity 2 was able to improve litter size and weight at parturition, but this positive effect disappeared after 22 days of lactation, instead feeding HF diet showed the optimal litter performance.     

Effect of oral administration of clinically relevant doses of dexamethasone on regulation of cytochrome P450 subfamilies in hepatic microsomes from dogs and rats

OBJECTIVE: To evaluate the effect of oral administration of dexamethasone (DEX) at clinically relevant doses on metabolic activities of cytochrome P450 (CYP) isoenzymes in dogs and rats. ANIMALS: 15 healthy 1-year-old male Beagles and 20 healthy 10-week-old male Wistar rats. PROCEDURE: Hepatic microsomes were harvested from dogs treated orally with DEX at 2.5 and 7.5 mg for 5 days and from rats treated orally with DEX at 0.75, 6, and 48 mg/kg for 5 days. 7-ethoxyresorufin, tolbutamide, bufuralol, and midazolam were used as CYP1A, CYP2C, CYP2D, and CYP3A substrates, respectively. Concentrations of metabolites formed by CYPs were measured by use of high-performance liquid chromatography, except for the resorufin concentrations measured by use of a fluorometric method. Reaction velocity-substrate concentration data were analyzed to obtain maximum reaction velocity (Vmax) and Michaelis-Menten constant (Km). RESULTS: Values of Vmax for midazolam 4-hydroxylation were significantly decreased by treatment with DEX at 2.5 and 7.5 mg in dogs, although values of Km were not affected. Values of Vmax for bufuralol 1'-hydroxylation were also decreased by treatment with DEX. In rats, values of Vmax for midazolam 4- hydroxylation were significantly decreased by treatment with DEX at 0.75 and 6 mg/kg but significantly increased at 48 mg/kg. Other reactions were not affected by treatment with DEX. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that DEX downregulates the CYP3A subfamily when administered at clinically relevant doses to dogs. The effect of downregulation of CYP3A in dogs treated with DEX should be considered to avoid adverse effects from coadministration of drugs.     

Caffeine administered during pregnancy augments subsequent lactation in mice.

Mice were administered caffeine (500 mg/liter of drinking water) from d 1 until d 18 of pregnancy. Before and after receiving caffeine, mice were given distilled water for drinking, as were controls. Litter size, birth weight, and offspring survival were not affected by caffeine, but litter weight on d 15 of lactation was increased by caffeine 84.0 +/- 3.1 g (n = 8) in controls vs 98.3 +/- 3.7 g (n = 7) in caffeine-treated mice (P less than .05). Mammary gland cell number, measured by the DNA content of mammae, was increased by giving caffeine during pregnancy (P less than .05). On d 18 of pregnancy, mammary DNA was .47 +/- .07 mg (n = 6) in controls vs .71 +/- .11 mg (n = 6) in caffeine-treated mice. On d 15 of lactation, mammary DNA was .96 +/- .12 mg (n = 8) in control vs 1.26 +/- .11 mg (n = 7) in caffeine-treated mice. RNA increased (P less than .05) parallel to DNA. In additional experiments, litters were cross-fostered and standardized to eight pups per litter. Mice were bred and caffeine was administered as described previously. At birth, eight pups from mice treated with caffeine or as controls during the preceding pregnancy were fostered to a control or caffeine-treated mother. In these experiments, litter weight on d 15 of lactation was 82 g for control litters nursing control mothers, 84 g for caffeine litters nursing control mothers, 96 g for control litters nursing caffeine mothers, and 99 g for caffeine litters nursing caffeine mothers (n = 7 per groups, pooled SE = +/- 3.4 g).(ABSTRACT TRUNCATED AT 250 WORDS)     

Flushing and altrenogest affect litter traits in gilts

Gilts (n = 267) were allotted to flushing (1.55 kg/d additional grain sorghum), altrenogest (15 mg.gilt-1.d-1) and control treatments in a 2 x 2 factorial arrangement. Altrenogest was fed for 14 d. Flushing began on d 9 of the altrenogest treatment and continued until first observed estrus; 209 gilts (78%) were detected in estrus. The interval from the last day of altrenogest feeding to estrus was shorter (P less than .05) with the altrenogest + flushing treatment (6.6 +/- .2 d) than with flushing alone (7.6 + .3 d). Ovulation rates (no. of corpora lutea) were higher (P less than .05) in all flushed gilts (14.5 +/- .4 vs 13.4 +/- .4), whether or not they received altrenogest. Flushing also increased the total number of pigs farrowed (.9 pigs/litter; P = .06) and total litter weight (1.43 kg/litter; P = .01), independent of altrenogest treatment. Number of pigs born alive and weight of live pigs were higher for gilts treated with altrenogest + flushing and inseminated at their pubertal estrus than for gilts in all other treatment combinations. In contrast, gilts receiving only altrenogest had greater live litter weight and more live pigs born when inseminated at a postpubertal estrus than when inseminated at pubertal estrus. We conclude that flushing increased litter size and litter weight, particularly for gilts that were inseminated at their pubertal estrus. Increased litter size resulted from increased ovulation rates, which, in nonflushed gilts, limited litter size at first farrowing.     

Trace elements in grass, cattle liver and sheep liver from districts surrounding Karatina, Kenya. I. Selenium

Samples of grass, cattle and sheep livers from the districts surrounding Karatina, Kenya, were analysed for their contents of selenium. The following mean values were found: Grass (n = 31): 0.19 +/- 0.17 mg Se/kg on dry matter basis, cattle liver (n = 96): 0.31 +/- 0.10 mg Se/ kg on wet weight, and sheep liver (n = 93): 0.55 +/- 0.25 mg Se/kg on wet weight. It is concluded that selenium deficiency is unlikely to occur in the districts included in this investigation.     

Quantification of mammary gland tissue size and composition changes after weaning in sows

The objectives of this study were to characterize the tissue compositional changes in porcine mammary glands after weaning and to determine whether administration of estradiol alters the profile of these tissue changes. Forty-five primiparous sows were assigned randomly to one of two treatment groups after weaning, control or estrogen treated. Estrogen-treated sows received twice-daily injections of estradiol-17beta (0.125 mg/kg of BW); control sows received vehicle injections. Sows were weaned at d 21 of lactation and killed on either d 0 (d of weaning; n = 5) or on d 2, 3, 4, 5, or 7 after weaning (n = 4 per treatment on each day). Teat order relative to suckling behavior was observed on the day before weaning to determine which mammary glands the piglets suckled. Suckled and non-suckled glands were identified from the teat order observation, and individual mammary glands were collected at slaughter. Mammary glands were trimmed of skin and extraneous fat pad, individually weighed, and bisected to measure cross-sectional area. The remaining half of each gland was ground and stored at -20 degrees C for chemical analyses. Frozen tissue was used for measuring tissue DNA, DM, protein, fat, and ash contents. Suckled mammary glands of sows undergo significant and dramatic changes during the initial 7 d after weaning, with significant changes occurring even by d 2 after weaning. Mean cross-sectional area of parenchymal tissue in suckled mammary glands decreased from 59.7 +/- 2.1 cm2 on the day of weaning to 26.8 +/- 2.3 cm2 by d 7 after weaning (P < 0.0001). Mammary gland wet weight decreased from 485.9 +/- 22.0 g on the day of weaning to 151.5 +/- 24.8 g by d 7 after weaning (P < 0.0001), whereas DNA decreased from 838.8 +/- 46.2 g on the day of weaning to 278.4 +/- 52.5 g by d 7 after weaning (P < 0.0001). The changes in gland wet weight and DNA during the period of mammary gland involution in the sow represent loses of over two-thirds of the parenchymal mass and nearly two-thirds of the cells that were present on the day of weaning. Estrogen treatment did not affect overall mammary involution during the first 7 d after weaning. Mammary glands that were not suckled during lactation had no further loss of parenchymal tissue during the first 7 d after weaning. Mammary gland involution in the sow is a rapid process and is probably irreversible within 2 or 3 d after weaning.     

Effects of dexamethasone,glucose infusion,adrenocorticotropin, and propylthiouracil on plasma leptin concentrations in horses

In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to the first day of treatment. In experiment 3, six light horse geldings received either 200 IU of adrenocorticotropin (ACTH) i.m. or vehicle twice daily for 4 days. ACTH increased (P < 0.001) cortisol concentrations. Further, ACTH resulted in increases (P < 0.01) glucose, insulin, and leptin concentrations. In experiment 4, plasma samples from four light horse stallions that were fed 6-n-propyl-2-thiouracil (PTU) at 6 mg/kg BW for 60 days to induce hypothyroidism were compared to samples from control stallions. On day 52, stallions receiving PTU had lower concentrations of thyroxine (P < 0.05) and triiodothyronine (P < 0.01) and higher (P < 0.01) concentrations of TSH. Leptin concentrations were higher (P < 0.01) in PTU-fed stallions from day 10 through 52. In conclusion, circulating concentrations of leptin in horses was increased by administering DEX. Treatment with ACTH increased cortisol and resulted in lesser increases in leptin, glucose, and insulin. In addition, PTU feeding results in lesser increases in leptin concentrations.     

Induction of parturition in cattle: effect of triamcinolone pretreatment on the incidence of retained placenta.

Two experiments were designed to determine whether pretreatment with triamcinolone acetonide (TRI) prior to induction of parturition with dexamethasone (DEX) and cloprostenol (CLO) would reduce the incidence of retained placenta. Experiment 1 was conducted to determine the optimum dosage of TRI and to approximate the optimum interval from TRI to induction with DEX + CLO. All cows received TRI on day 270 of gestation. Cows in group I received 1 mg/30 kg of body weight (BW) of TRI and were induced to calve with DEX + CLO on day 276. Cows in groups II and III received 1 mg/45 kg BW and were induced on days 276 or 277, respectively. Cows in groups IV and V received 1 mg/60 kg BW and were induced on days 277 or 278, respectively. Group VI cows served as untreated controls. There was no difference in the incidence of retained placenta among the treated and control groups. Experiment 2 was conducted to more precisely determine the optimum interval from pretreatment to induction treatment with the chosen dose of TRI. All cows in groups I, II, and III were pretreated with 1 mg/60 kg BW of TRI on day 270 of gestation and received DEX + CLO on days 275, 276 or 277, respectively. Group IV cows served as untreated controls. The incidence of retained placenta was higher (p < 0.05) in groups I and II than in the control group, with group III intermediate and not different from the others.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of recombinant porcine somatotropin on fetal and placental growth in gilts with reduced uterine capacity

Crowded uterine conditions were induced by unilateral hysterectomy-ovariectomy (UHO) in 42 gilts to determine the effect of recombinant porcine somatotropin on fetal and placental growth. Gilts were randomly assigned across three replicates to one of three treatments: Control (C; n = 14), daily injections of 1 mL saline from d 0 to 64 of gestation, Early (E; n = 12), 5 mg of rpST/d from d 0 to 30, followed by 1 mL saline from d 31 to 64, and Late (L; n = 16), 1 mL saline/d from d 0 to 29, followed by 5 mg of rpST/d from d 30 to 64 of gestation. Blood was collected from each gilt via jugular venipuncture at d 0 and every 15 d thereafter. Gilts were hysterectomized on d 65 of gestation. Length of placental attachment and fetal crown-rump length were measured. Placentas and fetuses were weighed. Placental length, wet weight, and dry weight were recorded. Treatment with rpST (either E or L) increased (P < 0.0001) maternal plasma IGF-I concentrations relative to controls. Treatment with rpST did not affect placental wet weight or placental DNA content. However, E and L treatments increased the percentage of placental protein (P = 0.01) and placental dry matter (P = 0.10) and increased contact area of uterine-placental interface (P = 0.01). Despite changes in placental composition and morphology, weights of fetuses collected from L-treated gilts did not differ from controls, whereas weights of fetuses collected from E-treated gilts tended to be less than controls (P < 0.06). Administration of rpST increased maternal IGF-I concentrations and placental surface area but failed to increase fetal growth in the UHO model. Therefore, mechanisms that are independent of maternal IGF-I or placental contact area may control early fetal growth under crowded uterine conditions.     

氯羟吡啶的特殊毒性——致畸作用

观察了国产氯羟吡啶对 Ｗ ｉｓｔａｒ 大鼠的致畸作用。氯羟吡啶以 ４、２０、１００、２００ ｍ ｇ／ｋ ｇ ４ 个剂量进行试验。结果,氯羟吡啶 １００、２００ ｍ ｇ／ｋ ｇ 组鼠妊娠率极显著低于阴性对照组 （ Ｐ ＜ ００１）, １００ ｍ ｇ／ｋｇ 的氯羟吡啶还对胎鼠平均窝重有显著不利影响,２００ ｍ ｇ／ｋｇ 组胎鼠平均身长及平均体重均显著小于阴性对照组 （ Ｐ ＜００５）。另外,２００ ｍ ｇ／ｋｇ 的氯羟吡啶可导致骨化迟缓增多和绝大部分胎鼠（１５／１６）多肋（１４ 对肋骨）,还引起母鼠体重下降,且胎仔平均畸形出现率显著高于阴性对照组。由此认为,氯羟吡啶有一定的致畸作用和胚胎毒作用。     

Effects of a novel carbohydrate and protein source on sow performance during lactation

Ninety-one primiparous and multiparous sows and their pigs were used to evaluate the effects of a novel carbohydrate- and protein-based feed ingredient (Nutri-Pal, NP) on sow and litter performance during lactation. Nutri-Pal is a feed supplement for sows that consists of a blend of milk chocolate, brewer's yeast, whey products, and glucooligosaccharides. The dietary treatments consisted of a corn-soybean meal control and a corn-soybean meal plus 5% NP fed from d 110 of gestation to weaning. The diets were formulated to be equal in total Lys and ME. Sows were allotted to treatment based on parity, body weight, and the date of d 110 of gestation. There were 46 and 45 sows per treatment over four farrowing groups. Litters were standardized to 10 pigs and weighed within 1 d of farrowing, and all sows weaned at least 8 pigs at an average age of 21 d. Sows were weighed on d 110 of gestation, d 1 postfarrowing, and at weaning. Sows were fed three times daily during lactation. Sows were checked twice daily after weaning for signs of estrus. The weaning weight of sows fed NP was increased (P < 0.10) compared with those fed the control diet. Sows fed the control diet tended (P = 0.11) to lose more weight per day from d 110 of gestation to weaning than the sows fed NP. Otherwise, sow response variables (sow weight on d 110 of gestation and d 1 postfarrowing, d 110 of gestation to d 1 postfarrowing and lactation weight change per day, d 110 of gestation to d 1 postfarrowing, lactation, and total feed intake, days to estrus, pigs born alive or dead, and litter and average pig birth weight) were not affected (P > 0.10) by diet. There were no effects (P > 0.10) of diet on litter performance response variables (pigs weaned, litter and average pig weaning weight and gain, and survival percent). The NP feed ingredient had minor effects on sow productivity, but it did not affect litter productivity indices.     

Progestagen supplementation during early pregnancy does not improve embryo survival in pigs

Progesterone supplementation during early pregnancy may increase embryo survival in pigs. The current study evaluated whether oral supplementation with an analogue of progesterone, altrenogest (ALT), affects embryo survival. A first experiment evaluated the effect of a daily 20-mg dosage of ALT during days 1-4 or 2-4 after onset of oestrus on embryo survival at day 42 of pregnancy. A control group (CTR1) was not treated. The time of ovulation was estimated by transrectal ultrasound at 12-h intervals. Altrenogest treatment significantly reduced pregnancy rate when start of treatment was before or at ovulation: 25% (5/20) compared to later start of treatment [85% (28/33)] and non-treated CTR1 [100% (23/23)]. Altrenogest treatment also reduced (p < 0.05) number of foetuses, from 14.6 ± 2.6 in CTR1 to 12.5 ± 2.5 when ALT started 1-1.5 days from ovulation and 10.7 ± 2.9 when ALT started 0-0.5 days from ovulation. In a second experiment, sows with a weaning-to-oestrous interval (WOI) of 6, 7 or 8-14 days were given ALT [either 20 mg (ALT20; n = 49) or 10 mg (ALT10; n = 48)] at day 4 and day 6 after onset of oestrus or were not treated (CTR2; n = 49), and farrowing rate and litter size were evaluated. Weaning-to-oestrous interval did not affect farrowing rate or litter size. ALT did not affect farrowing rate (86% vs 90% in CTR2), but ALT20 tended to have a lower litter size compared with CTR2 (11.7 ± 4.1 vs 13.3 ± 3.1; p = 0.07) and ALT10 was intermediate (12.3 ± 2.9). In conclusion, altrenogest supplementation too soon after ovulation reduces fertilization rate and embryo survival rate and altrenogest supplementation at 4-6 days of pregnancy reduces litter size. As a consequence, altrenogest supplementation during early pregnancy may reduce both farrowing rate and litter size and cannot be applied at this stage in practice as a remedy against low litter size.     

Studies in sow reproduction: 4. The effect of level of feeding in lactation and during the interval from weaning to remating on the subsequent reproductive performance of the early-weaned sow

An investigation of the effects of level of nutrition, both in lactation and from weaning to remating, on subsequent litter size and associated reproductive characteristics in the early-weaned sow is reported. Subjects were 75 sows in 5 groups. In 4 of the groups the sows were weaned after a 10-day lactation period. Group 5 was weaned following a 42-day gestation. The control group was fed up to 6.3 kg/day during lactation and 2.7 kg/day from weaning to remating. The 4 early-weaned groups were each fed differently. In lactation and during the inverval from weaning to remating they were fed either 2 or 4 kg/day. The group receiving only 2 kg/day during each period lost more weight than the others (p less than .05). Weight loss in lactation was significantly (p less than .001) affected by feeding. Sows weaned after a 10-day lactation period farrowed 2.7 piglets/litter less in the next parity than sows weaned after a 6-week lactation period. Weight losses during lactation were not related to subsequent litter size. Level of nutrition from weaning to remating in these tests had no influence on subsequent litter size. The early-weaned sow, even with large fluctuations in weight change over the period from parturition to remating, did not alter their ceiling for litter size. It seems unlikely that ovulation rate is the major factor limiting litter size in the early-weaned sow. Results suggest that embryo mortality following ovulation and coitus is increased in the early-weaned sow and that this effect then manifests itself as a ceiling to subsequent litter size.     

Effect of exogenous administration of steroids during the 1st month of pregnancy in sows and gilts on certain characteristics of the litter

Four trials were performed to evaluate the influence of i. m. application of progesterone and estrogens to 444 experimental and control sows and gilts, kept mostly under large-scale production conditions, during the first month of pregnancy, as exerted on the number of born piglets, live born piglets and on the average birth weight of the live born piglet in litter. In the first trial the experimental sows and gilts on the 16th and 17th days of gravidity were applied 25 mg of progesterone (P4) and 12.5 micrograms of estrone (E1), in the second trial in the same phase of gravidity 25 mg of P4 with 1.25 micrograms of estradiol-17 beta (E2) and in the third trial in the identical gestation phase only 12.5 micrograms of E2 per head/day. In the fourth trial, experimental animals were given 0.55 mg of P4 with 0.275 micrograms of E1 per one kg of live weight, for six subsequent days between the 25th and 30th day of gravidity. In all trials the control animals were administered, under the same conditions, only the vehicle. None of the performed trials proved a significant difference in the studied parameters of litters of experimental and control animals (P greater than 0.05). The application of 25 mg of P4 with 1.25 micrograms of E2 on the 16th and 17th days of gravidity per sow/day under the conditions of small-scale production with the extension of the evaluated criteria of litter quality had no significant influence (P greater than 0.5) on the above-mentioned indicators, nor on the average birth weight of the whole litter and on the average number and weight of piglets of experimental sows at weaning. These results document that the verified application of hormonal substances in the above-mentioned phases of the first month of sow and gilt gravidity do not represent, in view of the intensive reproduction of pigs, a suitable procedure.     

酵母多糖对环磷酰胺所致免疫损伤大鼠的拮抗作用

为研究酵母多糖(YP)对环磷酰胺(CTX)所致免疫损伤大鼠的拮抗作用,本实验将80只雄性SD大鼠随机分为YP(50 mg/kg)+CTX组、YP(100 mg/kg)+CTX组、YP(200 mg/kg)+CTX组、CTX对照组和正常对照组。YP+CTX组按剂量灌胃并称重,CTX和正常对照组则灌胃给予等量生理盐水,连续给药10 d;在第8 d、9 d,除正常对照组外,其余4组腹腔注射CTX 100 mg/kg。第11 d采血及对相关的免疫器官组织进行检测。结果显示,YP(100 mg/kg)组平均日增重和饲料报酬比正常对照组显著增加(p<0.05);胸腺指数,血清中IgA、IgG、表皮生长因子(EGF)、碱性磷酸酶(AKP)含量及空肠SIgA水平显著(p<0.05)或极显著(p<0.01)高于CTX对照组;结肠壁中前列腺素E2(PGE2)含量与CTX对照组相比显著降低(p<0.05)。以上结果表明,YP能提高大鼠的生长性能;YP对CTX所致免疫损伤具有一定的拮抗保护作用,其中100 mg/kg剂量的YP效果最为显著。