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.
Induction of parturition in the sow with prostaglandin F2α
Sows were injected with prostaglandin F2α to induce parturition. Blood was collected to determine the effect of PGF2α on plasma progesterone and estrogen levels. Parturition occurred significantly earlier (P<.01) in the 14 treated animals than in the 9 untreated animals. Nine out of fourteen treated sows farrowed within 48 h after treatment. Whereas untreated sows farrowed 11.6 ± 6.7 h after the predicted time of parturition, treated sows farrowed 48 ± 8.8 h before the predicted time. PGF2α was most effective in those sows in which plasma progesterone decreased quickly. Plasma estrogen levels remained reasonably constant after treatment.
The relation of food quantity to rumination behavior.
Preliminary work suggested that the quantity of food ingested by retarded individuals who usually ruminated following meals was related to the frequency and duration of ruminating responses. This possible relation was experimentally examined by systematically varying food quantity from regular portions to satiation levels for three retarded individuals who exhibited high levels of ruminating. A clear functional relation of food quantity to ruminating emerged, with satiation procedures producing rapid and large decreases in the relatively high frequencies and durations of ruminating characteristic of baseline food quantity conditions.