Clinical evaluations of a new prostaglandin analog in pigs: 1. Control of parturition and of the MMA-syndrome.
In two field trials, the parturition inducing and MMA preventing effects of the prostaglandin F(2alpha) analog (PGFA), K 11941, were explored. In trial 1, 100 sows were treated with 2 mg and 30 with 3 mg of K 11941 i.m. on day 112 of gestation; 125 sows treated on day 112 with 175 mcg cloprostenol (Planate, ICI) served as positive controls, and 248 sows treated with saline on day 112 of gestation were used as negative controls. Both PGF analogs were equally effective in inducing early parturiton: 84.6% and 83.2% of the sows had farrowed between 20 and 30 hours after treatment. Both treatments reduced stillbirth rate and piglet losses during the first 10 days of life, and lowered the incidence of MMA significantly (6.2 and 5.6% vs 27.3 and 24.2%; p<.001). In a second trial, parturitions were induced in four groups of 60 sows each with 2 mg K 11941, housed in farms with either a chronic high incidence of MMA (A: 45 to 65% or only a seasonal rise in MMA during summer (B: 10 to 50%). Groups were treated either in April/May or August/September; 240 salinetreated, control sows were used. K 11941-induced parturition reduced MMA incidence in farm A during both seasons and prevented the summer rise in farm B (p<.01). Fertility after weaning was impaired in herds with an increased incidence of MMA.
A farrowing management system using cloprostenol to control the time of parturition
During a one year period, 1459 sows and gilts were treated with cloprostenol to induce farrowing during the night on a large commercial pig farm. A regular farrowing supervision programme was used during each farrowing period. The mean time from treatment to onset of farrowing was 25.7 hours (SD 5.36) and 95.3 per cent of aniamls commenced farrowing within 36 hours. There was a significant (P less than 0.001) increase in the proportion of piglets reared to weaning during the trial when compared with both the previous year and the average for the previous three years. The proportion of stillborn piglets and mortality of liveborn piglets up to weaning were significantly (P less than 0.001) reduced during the period of the trial. Similarly the number of piglets crushed by the sow was significantly (P less than 0.001) reduced. However, the proportion of piglets dying as runts increased significantly (P less than 0.001) and as a result of an isolated outbreak of scouring during one month of the trial, the number of piglets lost because of scouring also increased significantly (P less than 0.001). Several practical and economic benefits were identified as part of the new management system.
Plasma estrogen, progesterone and luteinizing hormone levels during the estrous cycle in pigs.
Plasma estrogen progesterone and luteinizing hormone (LH) were det ermined during the estrous cycle in 6 pigs and during 24 hours on the 1st day of estrus (Day 0) in 4 pigs. Estrogen was low (less than 20 pg/ ml) during the cycle until Day 16 or 17 when it increased to a maximum of more than 50 pg/ml 1-2 days prior to estrus. Progesterone increased from 5.1 to 25.2 ng/ml between Days 2 and 6 and reached a maximum of 33.2 ng/ml by Day 12. Estrogen levels increased only after progesterone levels began to fall. LH decreased from 2.5 ng/ml on Day 0 to below 1 ng/ml until the next estrus when it increased to more than 5 ng/ml while estrogen was greater than 20 pg/ml and progesterone remained at 1 ng/ml.