Induction of parturition in the pig using a new prostaglandin analogue (K11941)

Eighty seven sows, taken from a herd whose mean gestation length was 116 days, were allotted at random on day 114 of gestation to one of five treatment groups as follows: (1) 175 mug prostaglandin analogue (closprostenol I.C.I. Ltd) (2) 1 mg K11941 (alfaprostol VETEM Ltd), (3) 2 mg K11941, (4) 3 mg K11941 (5) 2 ml saline (control). All prostaglandin analogues induced parturition significantly earlier than controls (P < 0.05), but there were no differences between any of the prostaglandin treatments in the interval to birth of the first piglet (P > 0.05). The mean intervals to parturition were 24.6, 22.3, 24.9, 30.7 and 53.0 hours for treatments 1, 2, 3, 4 and 5 respectively. Almost two-thirds of treated sows farrowed during the working period of the day following injection compared with a small proportion of control animals. Induction of parturition had no effect on birth weight, piglet survival to 3 weeks or on subsequent weaning to service interval in treated sows. Results show that this new analogue of prostaglandin (K11941) is effective in inducing farrowing in the sow.     

Dosage response evaluation of luprostiol administered to pregnant sows

Two trials were completed to investigate the effects of luprostiol in swine. The first trial was to evaluate parturition induced by various dosages of luprostiol compared with those of lutalyse or vehicle. Sows were assigned by random allotment to one of the following treatments on Day 112 of gestation: Group A, control (0 mg luprostiol); Group B (1.88 mg luprostiol); Group C (3.75 mg luprostiol); Group D (7.5 mg luprostiol); Group E (15 mg luprostiol); Group F (10 mg lutalyse). All prostaglandin-treated groups farrowed earlier than the controls (P<0.05), with Groups D (26.3 h), E (31.0 h) and F (25.8 h) having the shortest treatment-to-first-pig intervals, and Groups A (76.0 h), B (54.4 h) and C (40.0 h) having the longest intervals. Luprostiol-treated sows had the shortest farrowing time (P<0.05; range = 3.2 to 3.9 h). Significant differences were found for the time (min) between births: Group A (32.1), Group B (28.4), Group F (35.5) took longer than Group C (20.2), Group D (21.0) and Group E (21.6). In a second trial, 20 crossbred pregnant sows received either vehicle or luprostiol (7.5 mg) on Day 112 of gestation. Progesterone concentrations declined rapidly (P<0.05) in luprotiol treated females but were unchanged in control females during the 24-h collection period. The results of these trials show 7.5 mg luprostiol to be the most effective dose for inducing farrowing.     

Induction of parturition in swine with prostaglandin F(2)alpha, estradiol benzoate and oxytocin

Pregnant sows and gilts were administered either 0, 2.5, 5, 10 or 20 mg prostaglandin F(2)alpha (PGF(2)alpha) intramuscularly on Day 112 or 113 of gestation at 0800 h in an effort to induce parturition. The average interval from PGF(2)alpha injection to farrowing was 55.1 +/- 5.7, 29.4 +/- 3.1, 32.1 +/- 4.6, 27.8 +/- 1.8 and 26.9 +/- 1.1 h for 0, 2.5, 5, 10 and 20 mg, respectively. All PGF(2)alpha treatments increased (P < 0.01) over controls the number of sows farrowing 23 to 33 h after injection. The average gestation length was significantly shorter in treated gilts; however, no detrimental effect on pig performance or pig survivability was observed. A second trial evaluated the effect of a 10-mg dose of PGF(2)alpha on the induction of parturition in sows in order to obtain a majority of sows farrowing within normal working hours (0700 to 1700 h). The interval from injection to farrowing was decreased (P < 0.05) by PGF(2)alpha treatment (66.2 +/- 5.3 vs 28.1 +/- 2.2 h). Fifty-seven percent (P < 0.05) of PGF(2)alpha-treated sows farrowed between 0700 and 1700 h as compared to 13.6% for control sows. A third trial was conducted to examine a sequential treatment of PGF(2)alpha and oxytocin to control the time of parturition more precisely. Sows receiving only 10 mg of PGF(2)alpha farrowed on an average 31.1 +/- 1.4 h after injection. The injection of 40 IU oxytocin 24 to 28 h after PGF(2)alpha decreased (P < 0.05) the interval from PGF(2)alpha to farrowing (28.1 +/- 0.9 h). The addition of oxytocin increased (P < 0.05) the number of sows farrowing within 3 h of injection (33 vs 86% for PGF(2)alpha and PGF(2)alpha + oxytocin treatments, respectively). A fourth trial was designed to determine if the addition of exogenous estradiol benzoate (EB) to a sequential treatment of PGF(2)alpha and oxytocin would improve the predictability and synchronization of the induced parturition. Sows were assigned to receive either saline, 10 mg PGF(2)alpha + 40 IU oxytocin or 10 mg PGF(2)alpha + 5 mg EB + 40 IU oxytocin. The addition of EB reduced (P < 0.01) the variance in the interval from oxytocin to farrowing and added precision to the predicted time of induced parturition.     

Control of parturition in the sow using progesterone and prostaglandin

The effect of progesterone and prostaglandin administration on the timing of farrowing was studied in three groups of 25 sows each. Progesterone treatment (100 mg/day) on days 112, 113 and 114 of gestation (group I) significantly prolonged the gestation length to 116.4 +/- 0.4 (mean +/- s.e.) days compared to the control sows (group III; 115.5 +/- 0.2; P less than 0.05). Administration of prostaglandin (200 micrograms Cloprostanol intramuscularly) on day 115 of gestation following progesterone treatment (group II) resulted in a gestation length of 116.0 +/- 0.1 days, with the sows farrowing 25.4 +/- 1.0 h after the prostaglandin injection. 80% of the sows farrowed between 0800 and 1700 h of day 116 of gestation. Plasma progesterone levels were maintained by the exogenous progesterone during treatment. At farrowing, higher levels of progesterone were observed in groups I and II compared to controls. Prostaglandin treatment did not significantly alter withdrawal of progesterone in progesterone treated sows, suggesting that the actions of exogenous prostaglandin is primarily on the myometrium and the cervix. Hormonal treatment in late pregnancy did not have any adverse effects on piglet viability and growth rate, or subsequent reproductive performances of sows. Lactation was initiated normally, and the concentrations of lactose, protein, fat, IgG, Na+, Ca2+ and K+ in colostrum and milk were similar in all groups during the first 5 days of lactation.     

Parturition control in sows with a prostaglandin analogue (alfaprostol)

The objective of this study was to determine the dose of alfaprostol (18, 19, 20-trinor-17-cyclohexyl-13, 14 didehydro-PGF(2)alpha-methylester) and the day of administration most effective in inducing sows to farrow during normal working hours (0700 to 1700). One-hundred forty multiparous crossbred sows, taken from a herd whose mean gestation length was 114.3 days, were assigned to one of five treatment groups: 1) control vehicle-propylene glycol, 2) 0.5 mg alfaprostol (AP). 3) 1 mg AP, 4) 2 mg AP and 5) 3 mg AP. Sows received an intramuscular injection of AP between 0800 and 0830 on either day 111, 112 or 113 of gestation. Parameters studied included interval from injection to birth of first pig, farrowing interval, total number of pigs born, number born alive, average birth weight, percent stillborn, interval from weaning to next estrus and number born alive next litter. The mean intervals from injection to the birth of the first pig were 55.2 +/- 7.1; 41.1 +/- 5.1; 29.6 +/- 4.0; 24.3 +/- 1.1; 24.8 +/- 0.9 h for groups 1, 2, 3, 4 and 5, respectively (P<0.05). The percentage of sows that farrowed during normal working hours (23 to 33 h after injection) for groups 1, 2, 3, 4 and 5 were 15, 53, 60, 77 and 70%, respectively. Average birth weights (kg) for treatment groups 1, 2, 3, 4 and 5 were 1.54 +/- 0.05; 1.65 +/- 0.05; 1.59 +/- 0.05; 1.54 +/- 0.05 and 1.42 +/- 0.05, respectively (P<0.05). Mean differences in total number of pigs born and number born alive were also statistically significant (P<0.05) but stillbirth rate was not different (P>0.05) among treatment groups. These results indicate that a single injection of 1, 2 or 3 mg of alfaprostol will successfully induce parturition the following day in a majority of the treated sows.     

Clinical evaluation of a new prostaglandin analog in pigs: 2. Prophylaxis and therapy of anestrus after weaning in sows and first litter gilts

Alfaprostol, a new prostaglandin F(2alpha) (PGF) analog was given in a first trial at two dose levels known to be luteolytic (1 and 2 mg) to 200 sows and first litter gilts at the day of weaning after a 21-day lactation period; 189 controls received saline only. The treatment with alfaprostol shortened the interval to heat (6.0 vs 11.3 days; p<0.01) and increased the percentage of animals coming into heat within 10 days (84.0 vs 65.5%; p<0.01). Fertility to a.i. and litter size at the subsequent parturition were normal. In a second trial, 100 first litter gilts and 100 sows received alfaprostol, 1 or 2 mg, respectively, during July and August when high environmental temperatures tend to increase the rate of anestrus. Again, treatment with alfaprostol shortened effectively the interval to heat (5.9 vs 17.4 days in gilts, p<0.001; 5.6 vs 9.7 days in sows; p<0.01) and greatly increased the number of animals in heat (81 vs 47% in gilts, 83 vs 62% in sows; p<0.001). The effect on the seasonal incidence of clinical anestrus was marked; it was more pronounced in gilts than in sows, expressed by the length of time it took to resume cyclic functions and the lower percentage of animals coming into heat (p<0.001). The effect of alfaprostol was equally well expressed in first litter gilts and sows. In a third trial, 295 anestrous sows and gilts were treated on day 22 after weaning with either 2 mg alfaprostol, or 400 I.U. PMSG+200 I.U. hCG, or saline. Within five days after weaning, 38% of the alfaprostol treated, and 78% and 23% of the animals treated with PMSG/hCG and saline came into heat.     

Dietary fibre for gestating sows: effects on parturition progress, behaviour, litter and sow performance

In pig production, parturition progress is a key event for sow's reproductive performance, evaluated by piglet survival and piglets' performance. The aim of this study was to investigate the impact of feeding a high-fibre (HF) diet during gestation on parturition progress and reproductive performance of sows. Forty-two primiparous sows (Large-White × Landrace crossbred) were fed during gestation either a control diet (C diet; 2.40 kg/day, 3.2% crude fibre, in % of dry matter (DM)), or a HF diet (2.80 kg/day, 12.4% crude fibre, in % of DM). All sows received 33 MJ digestible energy per day. Continuous video recordings were done on the parturition day to determine postural changes (standing, sitting, lying) and behavioural activities (nesting behaviour, uterine contractions, restlessness, social behaviour towards piglets) during parturition. Duration of parturition and individual birth intervals were also measured. Piglets' growth was evaluated by weekly weighing from birth until weaning, at 26.5 days of age. Sows were weighed and backfat thickness was measured at mating, on day 105 of gestation, on the 1st day post partum, and at weaning. Durations of parturition and of birth intervals were not affected by the gestation diet and averaged 211 ± 12 min and 16.5 ± 0.9 min (mean ± s.e.), respectively. During the parturition progress, the gestation diet did not affect the frequency and the time devoted to postural and behavioural activities. Dietary treatment during gestation did not influence duration of gestation and weaning-to-oestrus interval, as well as litter size, and number of stillborn and weaned piglets. Piglet weight at birth did not differ between gestation dietary treatments but piglets nursed by HF sows showed a 13.5% greater growth rate during the 1st week of life (P < 0.01) and tended to be heavier at weaning (P = 0.06) compared with C piglets. The HF sows were leaner at the end of gestation (P < 0.05), but variations of sows' weight during gestation and lactation were not affected by the gestation diet. All sows lost the same amount of backfat thickness during lactation. During lactation, the average daily feed intake was not significantly affected by the gestation diet. This study shows that substituting a control diet for a HF diet during gestation has limited effects on farrowing progress and reproductive performance, but improved piglets' growth rate during the 1st week of life and tended to increase their live weight at weaning.     

Induction of parturition in crossbred sows with cloprostenol,an analogue of prostaglandin F2α

Forty-six crossbred sows were treated with a single intramuscular injection of 175 μg of cloprostenol on day 110, 112 or 113 of gestation and compared with 46 control animals farrowing naturally during the same period. Of the treated animals, 96% farrowed within 48 h. The mean time to the induced farrowing was 28 ± 1.2 h with 64% of the farrowings occurring during daylight hours. Piglet mortality was greater for farrowings induced at day 110 than for 112 or 113 days of gestation. Since the mean length of gestation for natural farrowings for untreated control sows was 115 ± 0.9 days, it may be concluded that farrowings could safely be induced within 2–3 days of the average expected farrowing date for the herd. For precise timing of treatment, the average gestation length for individual herds should be pre-determined and accurate breeding records are needed.     

Impact of parity on bone metabolism throughout the reproductive cycle in sows

Bone metabolism fluctuates throughout the reproductive cycle of sows to enable foetal growth and milk production. Although increased bone mineralisation is conceivable in sows during reproduction, a study of mineralisation in function of parity has not been performed. This study evaluated the fluctuations of markers for bone metabolism in primiparous and multiparous sows throughout a reproductive cycle. The experiment included ten multiparous and five primiparous commercial hybrid sows from one herd. The sows were monitored for one reproductive cycle and fed according to commercial dietary standards. Blood samples were taken in the morning before feeding at fixed time intervals before (day -5) and during gestation (insemination (day 0), 21, 42, 63, 84), around parturition (day 108, 112, parturition (115), 118), and during lactation (day 122, 129, 143). Serum osteocalcin (OC) concentration increased in early and mid-gestation (P=0.002) and decreased at the end of gestation (P=0.001), whereas crosslaps (CTX) concentration decreased during early and mid-gestation (P=0.002) and increased towards the end of gestation (P=0.001). Towards the end of lactation serum levels of both markers increased (P=0.007 and 0.013, respectively). For hydroxyproline (HYP) no significant fluctuation in function of the reproductive cycle was detected. Matrix metalloproteinase 2 (MMP2) concentration increased towards parturition for both primiparous and multiparous sows (P=0.001), whereas during lactation no significant fluctuations in function of the reproductive cycle were found. A parity effect was found for OC and CTX (P<0.010), but not for the other markers. These results demonstrate that bone metabolism differed between primiparous and multiparous sows, although in both groups a similar fluctuation throughout the reproductive cycle was observed.     

Synchronization of parturition in beef cattle with prostaglandin and dexamethasone

The effectiveness of dexamethasone and prostaglandin in combination for induction and synchronization of parturition in cattle was evaluated in 100 pregnant Angus, Hereford, Charolais and Simmental cows. Cows were distributed equally by breed, day of gestation and cow age to one of three treatments: 1) Control, 2) Dexamethasone (25 mg) plus prostaglandin F(2alpha) (25 mg) or 3) Dexamethasone (25 mg) plus fenprostalene (1 mg). Hormones were administered simultaneously from 275 to 283 d of gestation. Gestation length at calving for control cows differed significantly (P < 0.01) among breeds: Angus, 278.5 +/- 0.9; Hereford, 283.1 +/- 1.1; Charolais, 283.2 +/- 1.5; and Simmental, 285.4 +/- 1.2 d. For hormone-treated cows, 80% of the calves were born between 30 and 46 h after the hormone injections; overall mean was 37.6 +/- 1.1 h. Calving response did not differ (P >0.1) between cows treated with prostaglandin F(2alpha) versus fenprostalene (36.5 +/- 1.6 vs 38.6 +/- 1.6 h) or among cow age, day of gestation, or breed. Also, duration of labor, calving difficulty and calf viability did not differ between calves born at an induced or spontaneous parturition. The incidence of placenta retained for >24 h was higher for induced than spontaneous parturition (21.0 vs 0.0%), but it did not differ (P >0.1) between cows treated with prostaglandin F(2alpha) or fenprostalene (19.2 vs 22.6%). An acceptable degree of synchrony of parturition was attained by the administration of prostaglandin F(2alpha) or fenprostalene in combination with dexamethasone. The higher incidence of retained placenta in treated than control cows did not affect subsequent fertility. The longer biological half-life for fenprostalene than for prostaglandin F(2alpha) provided no improvement in increasing synchrony of parturition or decreasing frequency of retained placenta.     

Determination of clinical and luteolytic effectiveness of a prostaglandin analog in mares by a dose response study

In trials covering two seasons, 124 thoroughbred and 40 quarterhorse mares with either normal cycles (55 diestrous mares, 33 postpartum mares after foal heat) or in anestrus during the breeding season (76) were treated with either a novel PGF analog K 11941 or with the PGF analog prostalene (Synchrocept(trade mark)). K 11941 was used over a range of doses from 0.5 to 4.5 mg, while prostalene was applied at the recommended dose level of 2 mg. Blood progesterone determinations, clinical observations and the results of breeding confirmed that K 11941, at doses of 2 mg or larger, and prostalene, were effective and safe luteolysins; heat and ovulations occurred within the expected time intervals and fertility was satisfactory. Clinical data were converted into a response score (CRS) and an added fertility score (CRSF) for statistical evaluation and the establishment of a dose response curve. In both scores, 0.5 to 1.5 mg were significantly less effective than the higher dose levels (p<.0001). No significant differences were found for the 2 and 3 mg dose of K 11941 in diestrous and anestrous mares. In both indications, prostalene scored less (p<.05). Data analysis and establishment of a dose response curve point to 3 mg of K 11941 as the optimal dose.     

Peripartum Ca and P homeostasis in multiparous sows fed adequate or excess dietary Ca

The recent increased prevalence of uterine prolapses in sows around parturition has led to inferences that the prolapses may be associated with hypocalcemia. However, limited data are available to support that hypocalcemia occurs in sows. Hypocalcemia in dairy cows is associated with feeding excess dietary Ca during late gestation. The excess Ca is assumed to suppress homeostatic mechanisms critical to maintain serum Ca concentrations as the Ca demand increases during the early stages of lactation. In this experiment, sows were fed diets with excess Ca during late gestation and early lactation to assess the potential development of hypocalcemia in the peripartum period. Twelve crossbred (Large White × Landrace) multiparous gestating sows were fed a control diet (CON), 0.65% Ca to 0.38% standardized total tract digestible P (STTD P) and 0.67% Ca to 0.38% STTD P in gestation and lactation diets, respectively) or a high Ca diet (HCa, 1.75% Ca to 0.46% STTD P and 1.75% Ca to 0.45% STTD P in gestation and lactation diets, respectively). The diets were fed from gestation day 86 þ ± 1 until the end of lactation (27 þ ± 2 days period). On day 112 of gestation, indwelling venous catheters were placed in each sow. Blood samples were collected at 15-min intervals within four designated times (0700, 1000, 1300 and 1700 h) on gestation day 113 and lactation days 1, 3 and 5. Venous blood pH, gases (pO₂, pCO₂ and HCO₃⁻), electrolytes (K⁺, Na⁺ and Cl⁻), ionized Ca (iCa), metabolites (glucose and lactate), plasma total Ca (tCa), and P were analyzed. Overall, sows fed HCa diet had greater (P < 0.001) concentrations of blood iCa and plasma tCa than sows fed CON diets. No clinical signs of Ca metabolism disorders were observed. Unexpectedly, concentrations of plasma P in sows fed HCa diets were lower (P < 0.001) than in sows fed CON diets. Plasma P tended to decrease (P = 0.057) as day of lactation increased. Differences between dietary treatments for blood pH, gases, electrolytes and metabolites were not detected (P > 0.05). No evidence for hypocalcemia was detected in peripartum sows fed CON or HCa diets. These data imply that excess Ca in late gestation diets did not result in hypocalcemia during the peripartum period. Future experiments should focus on factors other than hypocalcemia to identify causes of uterine prolapses in sows.     

Effects of konjac flour inclusion in gestation diets on the nutrient digestibility,lactation feed intake and reproductive performance of sows

This study was conducted to investigate the effects of konjac flour (KF) inclusion in gestation diets of sows on nutrients digestibility, lactation feed intake, reproductive performance of sows and preweaning performance of piglets. Two isoenergetic and isonitrogenous gestation diets were formulated: a control diet and a 2.1% KF-supplemented diet (KF diet). Both diets had the same NDF and insoluble fiber (ISF) levels, but the KF diet had higher soluble fiber (SF) level. The day after breeding, 96 multiparous sows were assigned to the two dietary treatments. Restrict-fed during gestation, in contrast, all sows were offered the same lactation diet ad libitum. Response criteria included sow BW, backfat depth, lactation feed intake, weaning-to-estrus interval, litter size and piglet’s weight at parturition and day 21 of lactation. On day 60 of gestation, 20 sows were used to measure nutrient digestibility. Results showed that the digestibility of dry matter, gross energy, crude fiber and ADF were not affected by the dietary treatments. The inclusion of KF in gestation diets increased NDF digestibility (P<0.05) and tended to increase the digestibility of CP (P=0.05) compared with the control diet group. In addition, dietary treatment during gestation did not affect litter size, BW and backfat gain during gestation, lactation weight, backfat loss or weaning-to-estrus interval of sows. However, sows fed the KF diet consumed more (P<0.05) lactation diet per day than sows in the control group. Accordingly, sows fed the KF diet showed greater average piglet weights on day 21 of lactation (P=0.09), and the litter weight of sows fed the KF diet on day 21 of lactation increased by 3.95 kg compared with sows fed the control diet (not significant). In conclusion, the inclusion of KF in gestation diets increased lactation feed intake of sows and tended to improve litter performance.     

Myometrial oxytocin receptors and prostaglandin in the parturition process in the rat.

Parturition in rats is associated with an abrupt and marked increase in myometrial oxytocin (OT) receptor concentrations. In this study, we investigated the role of myometrial OT receptors in the initiation and the process of parturition. We produced chronic OT receptor blockade during the last 3 days of gestation by administration of a specific OT antagonist at 100 micrograms/day and 300 micrograms/day. We also suppressed OT receptor formation by inhibiting prostaglandin synthesis with naproxen sodium at 2 mg/day and 5 mg/day. We found that chronic blockade of OT receptors inhibited the uterotonic response to OT in Day 22 and Day 23 pregnant rats in a dose-dependent manner. OT antagonist treatment did not prolong the gestation period. However, the duration of parturition, fetal mortality, and the mortality incidence were increased in rats treated with the high dose of the OT antagonist compared to controls. Naproxen sodium at both dosage levels prolonged gestation by 24 h or longer, doubled the duration of parturition, and markedly increased fetal mortality and mortality incidence. Combined OT antagonist and naproxen treatment produced adverse outcomes similar to that produced by naproxen treatment alone. Myometrial OT receptor concentrations were markedly increased in all rats immediately postpartum, ranging from 210 to 425 fmol/mg protein compared to the 50 to 100 fmol/mg found in Day 21 and Day 22 pregnant rats. Correlation analyses between OT receptor concentrations and various parameters associated with gestation and parturition showed that there was a correlation between low OT receptor concentrations and long gestation period, prolonged parturition, and high fetal mortality rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of parturition in swine with prostaglandin analogs and oxytocin

Two trials were conducted to increase the effectiveness of parturition induction with PG analogs. In trial 1, 39 sows were treated with the analog Luprostiol (Pronilen, Vemie /Kempen). Of these, 19 received an additional injection of 30 i.u. oxytocin 24 h later. In trial 2, 126 sows were divided into four groups, three of which were treated with the analog Alfaprostol (Vetem /Milano), while one served as control. Two of the PG-treated groups received an additional oxytocin injection either 24 or 20 h later, respectively. The response to either of the PG analogs resembled that observed during earlier studies although the percentage of sows responding was somewhat lower (70% and 77%, respectively). Oxytocin increased the number of respondents to 84 and 89%, respectively, and parturition commenced promptly. In trial 1, parturition started within 2.1 +/- 1.6 (0 to 5) h after oxytocin, in trial 2 within 1.57 +/- 1.06 (0.5 to 3) h when the interval between prostaglandin and oxytocin was 24 h, and 1.81 +/- 0.84 (0.5 to 3) h when it was 20 h (x +/- SD ). Parturition and viability, birth weight and weaning weight of piglets were normal. The proportion of sows in trial 2 that showed increased body temperature during the first 3 days post partum was reduced from 22.9% in the control group to 8.6, 14.3 and 7.1% in the three groups receiving just PG or PG and oxytocin after 24 or 20 h, respectively.     

Luteolysis and cycle synchronization with a new prostaglandin analog for artificial insemination in the mare

Over a period of three years, 165 cyclic or anestrous Hanoverian mares received 177 treatments with 2, 3 or 4 mg of a novel luteolytic prostaglandin analog, K 11941. Heat and ovulations, indicating luteolysis, were observed after an average of 3.98 and 7.62 days, respectively, in 88.04% of 142 treated cyclic, postpartum and anestrous mares, and mares after an early loss of the conceptus. All doses tested were effective in inducing luteolysis as confirmed by determination of progesterone blood levels in samples collected daily, in 70 of 80 mares studied (87.5%). Attempts to achieve control of the cycle by various methods revealed that with K 11941 given once or twice, alone or in combination with hCG and/or an GnRH analog (Hoe 766), one can effectively concentrate estrus periods and follicular growth patterns, but can neither synchronize nor concentrate ovulations. Since most of the mares treated were confirmed problem mares, the pregnancy rate of 40.0% from first insemination at drug induced estrus, was regarded as satisfactory when compared to a pregnancy rate of 43.8% obtained with natural breeding in the same population. No drug related clinical signs of side-effects were observed.     

Growth and development of offspring following supplementation of sow diets with oil during mid to late gestation

This study aimed to determine the consequences of altering the fatty acid profile of sow diets during mid-to-late gestation; oils of different fatty acid composition were chosen as energy supplements to provide diets with different fatty acid profiles. Forty-eight multiparous sows were used to evaluate the effects of fat supplementation from day 60 of gestation until parturition. Sows were allocated to either 3 kg/day of commercial sow pellets (control; C) or an experimental diet consisting of 3 kg/day of commercial sow pellets supplemented with 10% extra energy in the form of excess pellets (E), palm oil (P), olive oil (O), sunflower oil (S) or fish oil (F). From days 0 to 60 of gestation, all sows were given 3 kg/day of sow pellets as for the C group. The E diet resulted in the heaviest piglets at birth whereas the offspring of O and S sows were the lightest at birth. The offspring of S sows remained lighter throughout the pre-weaning period, and were also the leanest by 14 days of age. In contrast, pigs born to S sows possessed more fat by the time they reached commercial end point (≈140 days of age). In conclusion, altering the fatty acid profile of the sow diet during the second half of gestation has long-term consequences for the development of their offspring.     

The influence of allyl trenbolone (Regumate) on the timing,duration and endocrinology of parturition in sows

A study was undertaken to evaluate the effects of using an oral progestagen for synchronisation of parturition in the sow. Multiparous Landrace X Large White sows were fed 20 mg allyl trenbolone daily from day 110 to 115 of gestation then 15 mg on day 116 (Group R; N = 12); untreated sows of similar background served as controls (Group C; N = 9). Blood samples, taken at 8-h intervals from day 110 of gestation to onset of parturition, then every 4 h until parturition was complete, were assayed for plasma levels of progesterone, unconjugated oestrone, cortisol and prolactin. Duration of farrowing, incidence of stillbirths and individual piglet birth weights were recorded. Five Group R sows farrowed during the period of progestagen administration, while for the remaining 7, the mean interval from last progestagen treatment to emergence of first piglet was 31.6 ±5.5 h. Gestation length, duration of parturition, and mean interval between successive births all were longer in Group R than in Group C (116.5 ± 0.34 compared with 115.0 ± 0.52 days, P < 0.01; 9.73 ± 1.98 compared with 3.08 ± 0.70 h, P < 0.01; and 53.4 ± 10.2 compared with 16.2 ± 2.4 min., P < 0.01, respectively). No significant treatment differences were apparent for litter size at birth, proportion stillborn or piglet birth weights. Profile analysis showed that plasma progesterone levels in Group R were lower (P < 0.05) during the 30 h prefarrowing, suggesting a longer mean interval between functional luteolysis and parturition in these animals. In both Groups plasma levels of unconjugated oestrone rose in the prefarrowing period, the levels being higher (P < 0.05) in Group R Peak oestrone levels occurred at the commencement of, and had declined to low levels by the completion of, farrowing. Cortisol levels exhibited a pattern similar to that of oestrone, although peak levels at parturition were lower in Group R (P < 0.01). Plasma prolactin levels in the 24 h prepartum rose faster and reached higher levels (P < 0.05) in Group C than Group R, but the difference was no longer apparent subsequent to first piglet emergence. It is concluded that the use of this progestagen to delay parturition upset the synchronisation of endocrine events at farrowing, resulting in an increased duration of parturition.     

Embryo survival, progesterone profiles and metabolic responses to an increased feeding level during second gestation in sows

This study describes reproductive and metabolic responses in sows fed at two different feeding levels from day 3-35 of second gestation. After insemination, 37 sows were assigned to one of two treatments: 1) Control: 2.5 kg/day of a gestation diet; 2) Plus Feed 3.25 kg/day of a gestation diet (+30%). Sow weight, back fat and loin muscle depth were measured at farrowing, weaning, start of treatment, day 14 after start treatment and end of treatment. Frequent blood samples were taken for progesterone, luteinizing hormone (LH), glucose and insulin, insulin-like-growth-factor-1 (IGF-1), non-esterified-fatty-acids (NEFA) and urea analysis. At day 35 after insemination sows were euthanized and their reproductive tract collected to assess ovarian, embryonic and placental characteristics. Plus Feed sows gained 5.4 kg more weight and 0.9 mm more back fat and tended to be heavier at slaughter compared to Control sows (193 vs. 182 kg, P = 0.06). No difference in loin muscle gain was found. Treatment also did not affect vital embryonic survival, which was 72.1 ± 3.9% for Control and 73.4 ± 3.2% for Plus Feed sows, resulting in, respectively, 15.9 ± 0.9 and 15.7 ± 0.7 vital embryos. No effect of treatment on any of the ovarian, embryonic or placental characteristics was found. Progesterone profiles during the first month of gestation, and LH characteristics at day 14 of gestation were not different between treatments. Progesterone concentration was lower (P < 0.05) 3 h after feeding compared with the prefeeding level on days 7-11 after first progesterone rise for Plus Feed and on days 8-10 after first progesterone rise for Control sows. At day 15, preprandial glucose and insulin concentrations were not different between treatments, insulin peaked later (48 vs. 24 min) and at a higher concentration in Plus Feed than in Control sows. Furthermore, glucose area under the curve (AUC) tended to be lower (−171.7 ± 448.8 vs. 1257.1 ± 578.9 mg/6.2 h, P = 0.06, respectively) for Plus Feed vs. Control sows. IGF-1 concentration was not different between treatments, but NEFA concentrations were lower for Plus Feed vs. Control sows (149.5 ± 9.2 vs. 182.4 ± 11.9 μm/L, respectively, P = 0.04) and urea concentration tended to be higher in Plus Feed than in Control sows (4.3 ± 0.1 vs. 3.9 ± 0.1, respectively, P = 0.13). None of the metabolic parameteres were related to reproductive measures. In conclusion, feeding 30% more feed from day 3 till d 35 of second gestation increased weight gain and resulted in lower NEFA concentrations, but did not affect progesterone, LH or IGF-1 and embryonic and placental characteristics.     

The use of dimenhydrinate in conjunction with dexamethasone for induction of parturition in beef cattle

Forty-eight crossbred Chianina cows (3 to 5 years of age), with an expected gestation length of 288 days, were randomly divided into four treatment groups to evaluate the use of dimenhydrinate (an antihistamine agent) in conjunction with dexamethasone (DEX) for inducing parturition in beef cattle. Group (A) received a 20 mg dose of DEX (im) on day 282 of gestation and a carrier vehicle (iv) 24 hours later (day 283); Group (B) was given a carrier vehicle (im) on day 282 and 500 mg of dimenhy-drinate (DMH) diluted in 200 ml of 2.5% dextrose-0.9% saline solution given (iv) on day 283 and Group (C) received 20 mg of DEX (im) on day 282 and 500 mg of DMH in solution (iv) on day 283 of gestation. The remaining 12 cows assigned to Group (D) were not handled and were allowed to calve under natural conditions. The number of cows calving and percent calving within 60 hours after the first injection were: 10(91%), none(0%) and 12(100%) for the DEX, DMH and DEX plus DMH groups, respectively. The mean gestation length of the control cows in Group (D) was 288.6 days. Frequency of dystocia was: 18.2, 8.3, 0 and 0% and retained placentae (>/=24 hours) was: 72.8, 16.6, 33.3 and 0% for DEX, DMH, DEX plus DMH and control groups, respectively. In this study, a 20 mg dose of DEX (im) followed 24 hours later with 500 mg of DMH (iv) was more successful for calving induction than when DEX or DMH was used alone. The combination DEX and DMH treatment induced calving in a shorter interval from treatment (P<.05) and decreased the incidence of retained placentae (P<.01) when compared with those induced following DEX treatment.