Ovarian response to fasting following high and low planes of nutrition in puberal gilts.

Abstract

AT the onset of their first estrus, 48 gilts which had been group fed 2.3 kg meal per day since they reached 170 days of age were allocated to an experiment of factorial design, the factors being plane of nutrition (high of low) and time of slaughter (day-16 of the first cycle or day-3 of the second cycle). The time of slaughter groups were further divided so that half the day-16 gilts were fasted from day-13 to day-16 and half the day-3 gilts from day-17 to day-3. Possible effects of mating on ovulation rate were also studied in the day-3 gilts. High plane gilts received meal ad libitum and low plane gilts 1.4 kg per day. High plane day-3 gilts produced a mean of 2.5 corpora lutea more than low plane (P<.01) but the effects of fasting and mating on number of corpora lutea were negligible. Corpora lutea weights were not significantly affected by nutritional treatment in the day-16 group. The numbers of follicles were not changed significantly by plane of nutrition or fasting in either the day-16 or day-3 groups. Follicular fluid weight, anterior pituitary gland weight and (in the day-3 groups) cycle length were also unaltered. The data indicate the substantial insensitivity to short-term fasting of the processes of folliculogenesis and ovulation in the puberal gilt.