Dietary protein intake during the oestrous cycle does not alter the ovulation rate in gilts

Protein restriction during puberty alters nutritional parameters and affects ovarian and uterine histomorphometry in adulthood in rats

In a large part of the population inefficient ingestion of proteins, whether for cultural, aesthetic or economic reasons, is a global concern. Low-protein diets can cause severe functional complications, mainly during the development and maturation of organs and systems, including the female reproductive system. The present study investigated the effect of nutritional protein restriction during puberty on the oestrous cycle and expression of sex steroid receptors (AR, ERα e ERβ) in ovarian and uterine tissues of adult rats. Protein restriction promoted lower body weight gain, feed efficiency and higher caloric intake. There was an increase in the oestrus phase arrest without changing the total length of the oestrous cycle. The consumption of low-protein diet also reduced the thickness of the uterine endometrium (uterine epithelium and endometrial stroma) in addition to increasing the number of primary and atretic follicles in the ovaries. Furthermore, the low-protein diet reduced the levels of androgen receptor (AR) and increased the oestrogen receptor β (ERβ) in the ovary, while no significant changes were observed in the uterus. Our study reinforces the importance of adequate protein intake during puberty, since physiological changes in this developmental period interfere with the histomorphometry of the ovaries and uteri, possibly resulting in impaired folliculogenesis and fertility in the reproductive period.

Oocyte maturation and embryo survival in nulliparous female pigs (gilts) is improved by feeding a lupin-based high-fibre diet

Inclusion of high levels of the high-fibre ingredient sugar-beet pulp in pre-mating diets has been shown to increase gonadotrophin concentrations and improve oocyte quality in nulliparous pigs (gilts). This study evaluated the effects of two alternative fibre sources on reproductive performance in gilts. Gilts received one of three diets from 3 weeks before puberty stimulation until Day 19 of the first oestrous cycle: control (39 g kg–1 fibre), bran (500 g kg–1 wheat bran, 65 g kg–1 fibre) or lupin (350 g kg–1 lupin, 118 g kg–1 crude fibre). Diet did not affect circulating LH concentrations or ovarian follicle size. However, a higher percentage of oocytes collected from lupin-supplemented gilts reached metaphase II in vitro compared with those collected from bran-fed or control gilts (89 ± 5% versus 72 ± 5% and 66 ± 5%, respectively; P < 0.05). Furthermore, in a second experiment, gilts fed the same lupin-based diet before mating had improved embryo survival (92 ± 5%) on Day 28 after mating compared with control gilts (76 ± 4%; P < 0.05). Therefore, feeding a high-fibre diet before mating can improve oocyte quality in gilts without changes in circulating LH, but this effect is dependent on the fibre source.