Longitudinal study of lymphocyte subsets and major histocompatibility complex-class II expressing cells in mammary glands of sows.

OBJECTIVE: To determine whether there is variation attributable to reproductive stage in lymphocyte subsets and major histocompatibility complex (MHC) class II expressing cells in mammary glands of sows. ANIMALS: 8 healthy primiparous crossbred sows that had been nursing piglets for 30 to 35 days. PROCEDURE: Needle biopsy of the mammary gland was performed after parturition, at midlactation, and after weaning. Various lymphocyte subsets and MHC class II expressing cells were detected immunohistochemically, using monoclonal antibodies. RESULTS: The number of CD8+ cells was significantly lower after parturition than after weaning but not significantly lower than at midlactation. The number of IgA-bearing cells was lower after parturition and after weaning than at midlactation. There were more B cells at midlactation than after weaning. There was no change over time in the number of CD4+ cells or MHC class II expressing cells. Immunohistochemically positive cells were detected only in interalveolar tissue. CONCLUSIONS AND CLINICAL RELEVANCE: Certain lymphocyte subsets in mammary glands of sows are affected by reproductive stage. The data do not support the hypothesis that development of postparturient coliform mastitis may be the result of impaired mammary immune defenses at parturition.     

The influence of additional fat in the diet of sows before and after parturition on piglet viability and performance

Two hundred and six mature sows were used to evaluate the effect of adding a total of 3 kg of fat to sow diets for an average of eight days before and seven days after parturition on piglet viability and performance.The addition of fat to the diet of sows had no effect on the percentage of piglets born alive, individual piglet birth weight, weight of the piglet at three weeks of age or the weaning to service interval in the sows. However, there was a significant increase in piglet survival (3.4%) between treated and control sows. Birth weight had a marked effect on piglet survival but there was no indication of a greater effect of added fat in the sows' diet on the survival of smaller piglets. A number of piglets were cross-fostered but fostering had no effect on piglet mortality. A comparison of the mortality of piglets born from sows receiving added fat and reared on controls and vice versa indicated that the major benefits of additional fat in the sow diet were effected in utero rather than via an increase in the quality of the sows' milk.     

Effects of intramuscular injections of folic acid during lactation on folates in serum and milk and performance of sows and piglets

In order to determine the effect of folic acid on serum and milk folates in lactating sows as well as on serum folates and growth rate of the piglets, sows (n = 25) received either saline or 15 mg folic acid i.m. each week from d 2 after parturition to weaning, 26 d later. Blood samples were drawn from all sows at 110 d of gestation and every week during lactation. Milk samples were taken at d 7 and 21 of lactation. Piglets were weighed and blood samples were collected weekly during lactation. Serum folates of sows increased during lactation. The rate of increase was more pronounced (P less than .0002) after folic acid injections. Milk folates concentrations decreased (P less than .0007) from d 7 to 21 of lactation but were higher (P less than .0001) in treated sows (11.8 +/- .7 ng/ml) than in control sows (7.9 +/- .4 ng/ml). Serum folates of piglets in control litters increased from 55.0 +/- 2.2 ng/ml at 2 d of age to a peak value of 86.3 +/- 3.1 ng/ml 2 wk later, and then gradually decreased. In piglets from treated dams, the time response curve was similar to that of the controls, but values were about 15% higher (P less than .01). The growth rate of piglets until 8 wk of age was not changed (P greater than .47) by folic acid injection of sows. More studies are needed to evaluate the practical importance of changes in folates status in establishing the folic acid requirements of lactating sows.     

Control of parturition in swine. 2. Study results of parturition synchronization in swine with the prostaglandin analog cloprostenol (I.C.I. 80.996: Estrumate)

Premature parturition was induced in 115 of 121 sows (95%) that had been given injections of 150 microgram or 200 microgram of "Estrumate", a prostaglandin analogues, on the 112th and 113th days of gestation. The average time that elapsed between injection and parturition of those 115 animals was 27.2 +/- 7.7 hours, with no difference being observed between gilts, on the one hand, and old sows, on the other. The time of gestation of the treated animals was shortened with significance from 114.6 +/- 1.6 days for the controls to 113.2 +/- 0.4 days. The average duration of parturition proper was 3.7 +/- 2.2 hours, the average litter being 11.2 +/- 3.3 piglets. The total number of piglets born was 1,320, with stillbirths accounting for 4.17%. The average weight at birth, 1,330 +/- 210 g, and the weight at weaning did not differ from weight figures recorded from the controls. The courses of parturition and puerperium were in agreement with normal biological standards. The sows treated were tested for their blood counts close to full term and for their endometrial histomorphology after weaning, with no side effects of "Estrumate" treatment being established. The behaviours of progesterone, 17-beta oestradiol, and cortisol in serum of "Estrumate"-treated sows were investigated, and congruence was established between spontaneous and prostaglandin-induced parturitions, which was in agreement with international literature. The conclusion is that 150 micrograms of 'Estrumate", administered to swine, after the 11th day of gestation has very good labour-inducing effects and ensures normal physiological parturition and piglet development.     

Effects of housing conditions of farrowing and nursing sows on development of piglets: our own studies and an evaluation of the literature

Results of rearing and growing 3250 piglets derived from 287 litters of 99 German Landrace sows in parities 1-11, from parturition throughout 5 weeks post-weaning, were compared in two farrowing systems. The Group-Farrowing System (GFS) was designed according to natural behaviour of wild pigs and contained 8 farrowing boxes allowing sows and their litters to move freely on an area of 85.2 m2. In contrast, the Single Farrowing System (SFS) was a pen in which sows and their litters were housed individually and could move freely on a restricted area of 6.7 m2. Sows were only fixed during farrowing. The first experiment with a suckling period of 35 days comprised 98 litters from 60 sows (parities 1-4). The second experiment with a suckling period of 28 days involved 189 litters of 70 sows (parities 1-11). In experiment 1, body weight of GFS-piglets was significantly higher by 4.57 kg (19%) at the age of 70 d compared with SFS-piglets. In the second experiment, the proportion of stillborns was significantly lower by 50% in GFS than in SFS. Furthermore, body weight of GFS-piglets showed a greater homogeneity during the first 35 d of life than that of SFS-piglets. In SFS, a positive correlation between parity of the sow and stillborn rate was observed. Behavioural studies in both experiments revealed that GFS-piglets, reared during the suckling period in close contact to other sows and piglets from other litters, were in a better condition at weaning than SFS-piglets. Comparisons with other GFS-types show that the success of farrowing in group-housing is dependent on the type of housing conditions, in particular on the possibility for sows and piglets to live according to their specific behavioural repertoire. The factors critical in this context are discussed.     

母猪猪瘟病毒抗体与仔猪母源抗体衰减规律的研究

为了研究仔猪猪瘟病毒(CSFV)母源抗体的衰减规律,本研究随机选择36头待产母猪,产后采血,选择每头母猪对应的仔猪连续采血至8周龄,分离血清,通过ELISA方法检测CSFV抗体阻断率,所测结果利用EXCEL拟合指数曲线,计算分析母猪CSFV抗体水平与仔猪母源抗体衰减规律。结果显示,36头母猪中母猪抗体阻断率80%以上6头,母猪抗体阻断率70%~79%的11头,母猪抗体阻断率60%~69%的8头,母猪抗体阻断率50%~59%的5头,母猪抗体阻断率49%以下的6头。3周龄仔猪抗体阻断率整体与母猪抗体阻断率相近且高度相关,相关系数为99%。母猪抗体阻断率在80%以上时,母源抗体对所产仔猪8周龄时仍然具有保护力;母猪抗体阻断率在70%~79%时,母源抗体对所产仔猪7周龄时不再具有保护力;母猪抗体阻断率在60%~69%时,母源抗体对所产仔猪5周龄时不再具有保护力;母猪抗体阻断率在50%~59%时,母源抗体对所产仔猪4周龄时不再具有保护力;母猪抗体阻断率49%以下时,母源抗体对所产仔猪3周龄时不再具有保护力。以上结果表明仔猪母源CSFV抗体随着仔猪周龄的增加逐渐衰减,由试验得出仔猪猪瘟疫苗首免日龄的计算公式:y=1.19x-46.55(x为母猪CSFV抗体阻断率,y为首免日龄)。因此,母猪抗体阻断率在80%以上时,仔猪母源抗体在60日龄不再具有保护力,仔猪猪瘟疫苗首免为56日龄;母猪抗体阻断率在70%~79%时,母源抗体对仔猪的保护持续到50日龄,仔猪猪瘟疫苗首免为42日龄;母猪抗体阻断率在60%~69%时和50%~59%时,母源抗体对仔猪的保护持续至36日龄和29日龄,仔猪猪瘟疫苗首免分别为28日龄和21日龄。本研究中所得母猪CSFV抗体水平计算母源抗体衰减变化,为选择母猪首免日龄,提高仔猪猪瘟疫苗免疫效果提供了科学依据。     

饲粮阴离子配比对母猪生殖机能与血清生化指标的影响

选取胎次相近、体况相似、健康状况良好的长×大二元杂交空怀母猪100头,将其均分成5组,每组20头。第1、2、3、4、5组母猪被分别喂以D1、D2、D3、D4、D5试验饲粮。在饲养试验期间,测定母猪窝产仔数,仔猪初生重、成活率、断奶重,母猪产后发情间隔天数（空怀天数）、返情率等繁殖指标;并分别于母猪采食试验饲粮后5d、孕后30d、产仔后7d,每组取8头母猪前腔静脉采血,测定血清中Cl-、Na＋、HCO3-、FSH、LH、Pg含量,GPT、GOT活性等生化参数。根据各项指标测定的结果可推断：第3组母猪饲粮中阴离子的配比（即添加：NaCl 0．40％、NaHC3。0．40％）最宜;其次是第4组母猪饲粮中阴离子的配比（即添加：NaCl0．40％、NaHCO。0．80％）较宜;再次是第2组母猪饲粮中阴离子的配比（即添加：NaCl0．40％、NaHCO30．80％）。第1、5组母猪饲粮中阴离子的配比似乎不够理想,即母猪饲粮中添加的NaCl过少（0．20％）或过多（0．80％）。     

Maternal behaviour and performance in first-parity outdoor sows

When sows and their litters are kept outdoors, much of the responsibility for the litter is shifted from the herdsman to the sow compared to when the sows are kept indoors. Therefore, the maternal ability, including maternal behaviour, is believed to be important in outdoor piglet production. The aim of this study was to describe maternal traits in conventionally bred first-parity sows kept outdoors. Nursing behaviour, sow activity, sow body reserves, litter size and piglet growth were studied in 40 first-parity sows during a seven week long lactation. The sows were kept in groups outdoors. Sow activity (lying down or active) and nursing behaviour (nursing frequency, nursing duration and nursing terminator) were recorded on videotapes at four days post partum (pp) and directly observed at four and six weeks pp. Cross suckling was observed at four and six weeks pp. Sows were weighed and measured for backfat depth five days before farrowing, two weeks pp and at weaning seven weeks pp. Piglets were weighed at four days pp, at two weeks pp and at weaning. We concluded that sow nursing behaviour and activity are individual characteristics repeatable within sows' late lactation. Less active sows are more available for suckling. Light and thin sows have an earlier and more progressed weaning process than heavier, fatter sows. A significant positive relation was found between sow appetite in early lactation and piglet growth until weaning. Sow nursing behaviour is not important for piglet growth when sows and piglets are held in groups, piglets have access to sow feed and piglets are weaned as late as at seven weeks of age.     

Effect of fractionated weaning on hormonal patterns and weaning to oestrus interval in primiparous sows

The effect of weaning the 4-5 heaviest piglets in the litter on day 33 of lactation and the remainder 2 days later (fractionated weaning) on plasma levels of prolactin, cortisol, oestradiol-17 beta (E2), progesterone (P4) and LH, as well as on the weaning to oestrus interval in primiparous sows was studied. Twelve crossbred sows were grouped into 6 pairs according to farrowing date and litter size. The litter of 1 sow in each pair (F) was weaned in 2 stages, and the other conventionally weaned at 35 days (C). Blood samples were collected via a permanent jugular vein catheter every 3 h from 9 a m to 9 p m daily throughout the experimental period, and intensively at 15 min intervals for 12 h on the day of first and final weaning and for 6 h on the day after each weaning. All sows were slaughtered following their first post-weaning oestrus and the reproductive organs were macroscopically examined. Lactational oestrus was not observed in any of the sows. Sows from 5 out of 6 pairs showed oestrus within 8 days of weaning and post-mortem examination showed normal ovulation. There was a tendency for the F sows to have a shorter weaning to oestrus interval, as compared with the C sows (5 of 6 pairs, 4.8 days v 5.6 days). The plasma levels of prolactin around weaning were not significantly different between the 2 groups. Within 6 h after final weaning, the prolactin concentrations decreased gradually from 7.6 and 8.7 to 1.6 and 1.7 microgram/l in the control and treatment groups, respectively. The plasma levels of cortisol, showing a diurnal rhythm (with the lowest level at 6 and/or 9 p m), did on no occasion differ between the 2 groups. On the day of final weaning, no diurnal rhythm was observed, with cortisol remaining high at 6 and 9 p m. The plasma levels of E2 and P4 were low until final weaning in both groups. After final weaning the E2 levels rose faster in the F sows than in the C sows, to 44.3 and 34.8 pmol/l, respectively, on day 2 (p less than 0.01). No significant differences in levels of plasma LH and the number of LH pulses were observed between the groups. After final weaning the average and base levels of LH and the number of LH pulse(s) increased significantly.     

The content of Hb in blood and proteins, Fe, Fe-binding capacity, Cu and Zn in the blood plasma of sows and their piglets at the time of birth, after the uptake of colostrum and with different Fe supply

Keeping of piglets on slatted metal floor, without complementary iron supply, caused anaemia within seven days from parturition. Hb levels in the blood dropped from 7.00 +/- 1.16 to 3.47 +/- 0.74 mmol/l. Iron deficit reduced growth and vitality. The iron levels in blood plasma of the piglets tested varied between 5 and 35 mumol/l, immediately after parturition. Intraperitoneal or oral administration of Fe-dextran (150 mg Fe) on the first day after parturition resulted in physiological iron levels in blood plasma, after seven days. Yet, when 14 days had passed, the levels were similar to those recorded from piglets without additional iron supply. Iron bonding capacity of blood plasma increased in piglets of all groups up to the seventh day from birth. Death occurred, on the second day of age, to many piglets with protein levels below 50 g/l plasma. Copper levels in blood plasma of newborn piglets were below those recordable from sows, but they went up by more than three times of their original values up to the seventh day from birth. In piglets, zinc, levels of blood plasma after parturition were higher than those of sows and went up by some 50 percent, within seven days from birth.     

不同形式补铁补硒对仔猪生长性能、血液生化指标、免疫性能的影响

[目的] 比较母猪和仔猪不同形式的补铁补硒对仔猪生产性能、血液生化指标、免疫性能的影响。[方法] 将32头母猪随机分为8组,每组4头,1~4组基础日粮中添加硫酸亚铁和亚硒酸钠,5~8组基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸。2组和6组母猪所产仔猪于3日龄肌注铁硒合剂;3组和7组仔猪基础日粮中添加硫酸亚铁和亚硒酸钠;4组和8组仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸;1组和5组仔猪饲喂基础日粮,不接受任何形式的补铁补硒。母猪预产期前30 d开始饲喂试验日粮,仔猪7日龄时开始饲喂试验日粮,试验至仔猪21日龄断奶结束。测定并比较不同组别仔猪生长性能指标、血液生化指标以及免疫性能指标,以及不同组别母猪初乳和常乳中的铁硒含量。[结果] 在仔猪补铁补硒形式相同的条件下,母猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸（5~8组）与基础日粮中补充硫酸亚铁和亚硒酸钠（1~4组）相比,能够显著（P<0.05）或极显著（P<0.01）提高仔猪的初生重、断奶重、断奶存活率、断奶合格率,2日龄和21日龄血浆铁含量、血浆硒含量、血红蛋白含量、血浆转铁蛋白含量、IgA含量、IgG含量、IgM含量,以及母猪初乳和常乳中的铁硒含量;在2种形式的母猪补铁补硒条件下,与不补铁补硒相比,仔猪不同补铁补硒形式（2~4组和6~8组）对其断奶重、断奶存活率、断奶合格率,以及21日龄血浆铁含量、血浆硒含量、血红蛋白含量、血浆转铁蛋白含量、谷胱甘肽过氧化物酶活性、IgA含量、IgG含量、IgM含量均有极显著（P<0.01）的提高作用,并且仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸的效果优于肌注铁硒合剂和基础日粮中补充硫酸亚铁和亚硒酸钠。[结论] 母猪和仔猪基础日粮中添加甘氨酸螯合铁和硒代蛋氨酸,能有效提升仔猪的生长性能、血液生化指标和免疫性能。     

Clinical and endocrinological studies in primiparous post partum sows. Effects of lactation length and litter size

The object of this investigation was to determine the relationships between clinical findings and hormonal patterns in primiparous sows with different lactation length and litter size during lactation, weaning and to the first oestrus. Seven pairs of primiparous full sib sows were used to determine the effect of lactation length with normal litter size. One sow of each pair was assigned to nurse the piglets for 3 weeks (group A) while the other nusred for 5 weeks (group B). Another 8 primiparous sows (group C) were assigned to nurse 2–4 piglets during a 5-week lactation period. Oestrus detection was performed twice daily and laparoscopic examination every 2 weeks. If the sows did not come in oestrus within 3 weeks after weaning they were slaughtered. Peripheral plasma levels of progesterone, oestradiol-17β and LH were estimated by radioimmunoassays throughout the experimental period.     

Effect of dietary L-carnitine supplementation on growth performance of piglets from control sows or sows treated with L-carnitine during pregnancy and lactation

Previous studies showed that supplementation of sows' diets with L-carnitine increases body weights of their piglets at birth. This study was performed to investigate whether piglets of sows treated with L-carnitine differ in their growth potential from that of piglets of untreated control sows after weaning. It was also investigated whether supplementation of piglets' diets with L-carnitine improves their growth after weaning. In two trials, piglets of the first litters of primiparous sows (trial 1) and the second litters of the same sows (trial 2) were divided into four groups: group 1, piglets of control sows, fed a control diet; group 2, piglets of control sows fed a diet supplemented with 30 mg L-carnitine/kg; group 3, piglets of L-carnitine-treated sows, fed a control diet; group 4, piglets of L-carnitine-treated sows fed a diet supplemented with 30 mg L-carnitine/kg. Mean initial body weights of the piglets of the four groups were identical. They were 8.5 kg in trial 1 and 12.5 kg in trial 2. Diets were fed ad libitum over a period of 35 days. Piglets from sows treated with L-carnitine did not differ in body weight gains, feed intake and gain : feed ratio from those of control sows. In trial 1, piglets supplemented with L-carnitine had higher body weight gains (p < 0.005) and showed a tendency towards a higher gain : feed ratio (p = 0.09) than piglets fed the control diets. In trial 2, no significant difference in these parameters emerged between piglets fed the diet supplemented with L-carnitine and those fed the control diet. In conclusion, this study shows that dietary L-carnitine treatment of sows does not improve the growth potential of their piglets after weaning under the conditions of equal initial body weights. The study also shows that L-carnitine supplementation of their diets improves the growth performance in light piglets of primiparous sows.     

Immunoglobulins in piglets from sows heat-stressed prepartum

Sows were subjected to moderate heat stress in a chamber (32 C) from d 100 of pregnancy until less than 8 h before delivery of first piglet, while control sows were in a thermoneutral chamber (21 C) or farrowing house (22 C). Blood serum and colostrum at parturition of heat-stressed sows and their piglets' serum at birth had elevated cortisol concentrations. Total protein, globulin and immunoglobulin G (IgG) concentrations in sow serum tended to decrease as parturition time was approached; albumin did not change. Total protein and IgG concentrations in colostrum at parturition and in milk 24 and 48 h later tended to be lower in heat-stressed sows. Concentrations of these four protein fractions (total, globulin, IgG and albumin) in piglet serum at birth did not differ among treatment groups, but soon after colostrum ingestion they increased markedly in all groups. Therefore, in all groups total protein remained constant while globulin and IgG decreased. Globulin concentration on d 1 was lowest in piglets from heat-stressed sows, but its rate of decrease after d 1 was not affected by sow treatment. Immunoglobulin G concentration was 11 mg/ml lower, but its rate of decrease through postnatal d 20 was slower in piglets from heat-stressed sows than in those from control sows; a 10-mg/ml difference in IgG concentration on postnatal d 1 has been associated with increased preweaning mortality in piglets. Higher cortisol concentration in serum and lower IgG in colostrum of sows under heat stress was associated in their piglets with higher serum cortisol at birth and lower serum IgG for the first 20 d postnatum.     

Prevention of anestrus in sows after the 1st and 2d parturition

The procedure of prevention of anoestria after the weaning of piglets was verified in 389 experimental and 332 control sows of the Prestice breed. The set of animals under study included 77 experimental and 122 control primiparae, 68 experimental and 71 control secundiparae, and 244 experimental and 139 control multiparae (i.e. sows with three or more parturitions). The experimental sows were treated with 1000 IU of serum gonadotropin ad usum vet.-Bioveta-(PMSG) the first day after the weaning of piglets and with 300 IU of chorion gonadotropin (HCG) in the Praedyn inj. Spofa preparation together with 1 ml of Dirigestran inj. Spofa (40 micrograms LHRH) 72 hours later. Control sows were not treated with hormones. The treated primiparae and secundiparae respectively, had a significantly higher percentage of oestrus onset within 10 days after weaning and lower occurrence of anoestria over 10 days after weaning by 31.25 per cent (P less than 0.001), and 21.36 per cent (P less than 0.02) respectively as compared with untreated controls. In the set of secundiparae, the studied hormonal treatment speeded oestrus onset by a significant (P less than 0.01) shortening of the interval from weaning to the first insemination by 0.79 day and by a more frequent onset of oestrus within only 5 days after weaning of piglets. The values of the other criteria of reproduction studies, i.e. percentage of pregnancies after the first insemination, total number of born piglets and number of liveborn piglets converted per one litter in treated primiparae and secundiparae did not differ significantly (P greater than 0.05) from the control.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of magnesium on the performance of sows and their piglets

The objective of this study was to evaluate the effects of supplemental magnesium(Mg) on the performance of gilts and parity 3 sows and their piglets.Fifty-six gilts(Trial 1) and 56 sows(Trial 2) were assigned to one of 4treatments according to their mating weight,respectively.The treatments comprised corn-soybean meal based gestation and lactation diets(0.21%magnesium) supplemented with 0,0.015,0.03,or 0.045%Mg from mating until weaning.The results showed that magnesium supplementation significantly(P 0.05) reduced the weaning to estrus interval in both gilts and sows.There were significant effects(P 0.05) of supplemental magnesium on the total number of piglets born,born alive and weaned in sows.In late gestation and lactation,the digestibility of crude fiber(quadratic effects,P 0.05),and crude protein(P 0.05),were significantly influenced by magnesium in gilts and sows,respectively.There were differences among the 4 groups in terms of the apparent digestibility of dry matter and crude fiber in sows(P 0.05) during both early and late gestation.The apparent digestibility of gross energy was increased for sows in late gestation(P 0.05),and lactation(quadratic effects,P 0.05).At farrowing and weaning,serum prolactin levels and alkaline phosphate activities linearly increased in sows as the Mg supplementation increased(P 0.05).Serum Mg of sows at farrowing and serum urea nitrogen of sows at weaning was significantly influenced by Mg supplementation(P 0.05).The Mg concentration in sow colostrum and the serum of their piglets were increased by supplemental magnesium(P 0.05).In addition,growth hormone levels were linearly elevated(P 0.05) in the serum of piglets suckling sows.Our data demonstrated that supplemental magnesium has the potential to improve the reproduction performance of sows,and the suitable supplemental dose ranged from 0.015%to 0.03%.     

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.     

Effect of intramuscularly administered beta-carotene on reproductive performance in sows

The present study investigated the effects of intramuscularly administered beta-carotene on reproductive parameters in female pigs. A total of 216 multiparous sows were observed from weaning of their litters until the next farrowing. On the day of weaning, the animals were allocated to two groups. Sows of the treatment group were injected with 70 mg beta-carotene both at the day of weaning and after the last insemination, sows of the control group were left untreated. For all sows, intramuscular injection of beta-carotene resulted in a significant increase of the total number of piglets born per litter by 1.2 (p < 0.05). When sows were divided by parity, beta-carotene treatment in second parity sows increased the total number of piglets per litter (beta-carotene 13.7 +/- 1.2, control 11.2 +/- 3.7, p < 0.01) and the number of piglets born alive (beta-carotene 12.0 +/- 2.7, control 10.0 +/- 3.4, p < 0.05). No such effect was seen in sows of third or higher parity. No other reproductive parameters were affected by beta-carotene supplementation. Tolerability and safety of the administered preparation were good. No side effects related to the medication were observed. The effect of beta-carotene on reproduction is thus affected by parity of the sows. This effect seems to be exerted mainly during early pregnancy and is most likely beta-carotene-specific and independent from its role as a vitamin A precursor.     

Split-weaning before altrenogest synchronization of multiparous sows alters follicular development and reduces embryo survival

This study used split-weaning (SW) to induce differences in follicle size at weaning and study its consequences for follicle development during and after post-weaning altrenogest feeding and for reproductive performance. Multiparous sows (n=47) were assigned to SW (n=23; litter size reduced to the six smallest piglets 3 days before weaning) or control (C; n=24; normal weaning). Altrenogest (20 mg/day) was fed to all 47 sows from Day -1 till Day 5 (complete weaning = Day 0). Follicle size on Day 1, 2 and 8 was smaller in C than in SW (p ≤ 0.05). Ovulation rate was similar, but C sows had higher embryo survival rate (ESR) than SW sows (83 ± 19 and 58 ± 31%, respectively; p=0.001). SW sows with low ESR (<63%; n=10) had a greater follicle size on days 3-6 than SW sows with high ESR (>63%; n=10; p ≤ 0.04). A decrease in follicle size between Day 5 and 6 of altrenogest feeding was associated with increased ESR in both treatments (p=0.002). Follicle pool analyses (assessment of all follicles >2 mm) revealed that on Day 3, sows with low ESR had a higher % of follicles >5 mm compared with sows with high ESR (30% vs 10%; p=0.04). Thus, sows in which follicle growth was less suppressed during altrenogest feeding had a lower ESR. These effects on follicle development and ESR were more pronounced in split-weaned sows.     

Comparative effects of sodium butyrate and flavors on feed intake of lactating sows and growth performance of piglets

We examined the effects of sodium butyrate and flavors on feed intake of lactating sows and growth performance of piglets. A total of 52 primiparous sows (Large White) were randomly divided into four treatments (n = 13) and received 6 g/kg sodium butyrate (SB), fruit‐milk (FM) flavor and fruit‐milk‐anise (FMA) flavor with pair feeding to the mothers receiving the control diet. The feeding trial lasted for 29 days, including 21 days of nursing and 8 days of post‐weaning period, respectively. The nursing and weaning piglets received creep diets with the same flavor or SB supplement as their mother. The results showed that FMA flavor increased average daily feed intake (ADFI) of lactating sows (P < 0.01), as well as improved litter weight gain (P = 0.05) and ADFI (P < 0.01) of nursing pigs among treatments. Indeed, greater ADFI and average daily gain of weaning piglets for the initial 8 days after weaning was observed in the FMA group compared with those in the control group (P < 0.01). These findings indicated that adding FMA flavor was superior to SB for increasing feed intake of lactating sows and improving growth performance of piglets.