OBJECTIVE: A previous study demonstrated for the first time that a drug such as caffeine, administered prior to ovulation and genomic activation, causes a quantitative difference in growth-promoting energy utilization in a proportion of 5-day-old blastocysts. The objective of the present study was to investigate whether developmental changes induced by caffeine administered throughout the estrus cycle prior to fertilization are sustained throughout pregnancy and after birth. METHODS: Caffeine was administered to rats throughout the estrus cycle prior to fertilization, with control and experimental groups subdivided into preimplantation and postimplantation categories. Preimplantation fertilization rate was assessed on day 4 of pregnancy by a pregnancy-induced elevation in maternal plasma progesterone concentration, or by flushing each uterine horn on day 5 of pregnancy to determine the presence or absence of a litter. Postimplantation fetuses were collected on gestational day 12 or allowed to go to term. RESULTS: Preconceptual caffeine exposure significantly reduced maternal fertility by the failure of a proportion of the litters to implant, rather than curtailing preimplantation development or postimplantation losses. Postnatal mortality between weeks 0 and 1 was elevated and the weekly incremental growth rate of the pups from week 3 through week 7 was significantly reduced in the preconceptually caffeine-treated offspring. Experimental females reached puberty at the same age as the controls but at a significantly lower body weight. Gestation length, hirthweight, litter size, sex ratio, and anogenital distance (a measure of prenatal androgenization) were not affected by preconceptual caffeine treatment. CONCLUSIONS: It was concluded that the reduced fertility rate in preconceptually caffeine-exposed rats was due to the failure of litters to implant rather than to a reduced fertilization rate, which was normal. It was further concluded that the growth rate over the neonatal and prepubertal periods of surviving pups in the caffeine-treated group was subnormal.

Animals↗

PubMedDate not supplied

Immunization against polyandroalbumin leads to increases in lambing and tailing percentages.

A series of 10 farm trials was conducted in which the lambing performance of ewes immunised against polyandroalbumin was compared with that of untreated ewes in the same flock. The trials show that polyandroalbumin treatment is a reliable method of increasing lambing and tailing percentages in New Zealand flocks. An average of 39 extra lambs born per 100 ewes tupped was achieved on farms where ewes were given two treatments about four weeks apart and rams were introduced 18-26 days after the second dose. On farms where rams were introduced less than 12 days after this booster injection an average of 19 extra lambs born per 100 ewes tupped resulted. On farms where rams were introduced at 18-26 days post booster injection an average of 35 extra lambs were tailed for every 100 ewes tupped. The response for immunization increased in direct relation to the liveweight of the ewes at tupping.

Journal Article↗