Beneficial effects of a decreased meal frequency on nutrient utilization, secretion of luteinizing hormones and ovarian follicular development in gilts

Abstract

Background Replacement gilts are typically fed ad libitum, whereas emerging evidence from human and rodent studies has revealed that time-restricted access to food has health benefits. The objective of this study was to investigate the effect of meal frequency on the metabolic status and ovarian follicular development in gilts. Methods A total of 36 gilts (Landrace × Yorkshire) with an age of 150±3 d and a body weight of 77.6±3.8 kg were randomly allocated into one of three groups (n = 12 in each group), and based on the group allocation, the gilts were fed at a frequency of one meal (T1), two meals (T2), or six meals per day (T6) for 14 consecutive weeks. The effects of the meal frequency on growth preference, nutrient utilization, short-chain fatty acid production by gut microbial, the post-meal dynamics in the metabolic status, reproductive hormone secretions, and ovarian follicular development in the gilts were measured. Results The gilts in the T1 group presented a higher average daily gain (+ 48 g/d, P < 0.05) and a higher body weight (+ 4.9 kg, P < 0.05) than those in the T6 group. The meal frequency had no effect on the apparent digestibility of dry matter, crude protein, ether extract, ash, and gross energy, with the exception that the T1 gilts exhibited a greater NDF digestibility than the T6 gilts (P < 0.05). The nitrogen balance analysis revealed that the T1 gilts presented decreased urine excretion of nitrogen (− 8.17 g/d, P < 0.05) and higher nitrogen retention (+ 9.81 g/d, P < 0.05), and thus exhibited higher nitrogen utilization than the T6 gilts. The time-course dynamics of glucose, α-amino nitrogen, urea, lactate, and insulin levels in serum revealed that the T1 group exhibited higher utilization of nutrients after a meal than the T2 or T6 gilts. The T1 gilts also had a higher acetate content and SCFAs in feces than the T6 gilts (P < 0.05). The age, body weight and backfat thickness of the gilts at first estrous expression were not affected by the meal frequency, but the gilts in the T1 group had higher levels of serum luteinizing hormone on the 18th day of the 3rd estrus cycle and 17β-estradiol, a larger number of growing follicles and corpora lutea, and higher mRNA expression levels of genes related to follicular development on the 19th day of the 3rd estrus cycle. Conclusions The current findings revealed the benefits of a lower meal frequency equal feed intake on nutrient utilization and reproductive function in replacement gilts, and thus provide new insights into the nutritional strategy for replacement gilts, and the dietary pattern for other mammals, such as humans.

Dietary Fiber Supplementation in Replacement Gilts Improves the Reproductive Performance From the Second to Fifth Parities

“…The long-term benefits of the SF supplementation during the replacement phase could be attributed to several reasons. The dietary fiber treatment during the replacement phase resulted in numerous ovarian follicles ( 17 , 18 ) and enhanced oocyte quality ( 21 , 22 ). When gilts were fed with graded levels of inulin and cellulose from 92 d of age, the number of healthy ovarian follicles was linearly increased and the number of total follicle reserve per ovary increased by 40% when gilts were fed 100% more dietary fiber than the control gilts ( 17 ), and the number of atretic follicles was linearly decreased as the increase of the dietary fiber level ( 17 ).…”

Effects of Dietary Fiber, Crude Protein Level, and Gestation Stage on the Nitrogen Utilization of Multiparous Gestating Sows

“…Gestating sows were moved to stainless-steel metabolism crates to measure their nitrogen balance, as previously described [ 4 , 12 ]. There were two nitrogen balance trials conducted on days 30 to 38 and 90 to 98 of pregnancy.…”

Effects of Chronic Exposure to Diets Containing Moldy Corn or Moldy Wheat Bran on Growth Performance, Ovarian Follicular Pool, and Oxidative Status of Gilts

“…The numbers of corpora lutea and antral follicles with diameters between 1 and 3 mm and >3 mm were recorded. The cumulus oocyte complex (COC) and granulosa cells (GCs) were obtained in large antral follicles from ovaries on both sides with diameters > 3 mm as previously described [25], snap-frozen, and stored at −80 • C.…”

“…For analysis, the right ovary was cut into four sagittal slices that were then fixed in 4% paraformaldehyde (100 mmol/L phosphate buffer, pH 7.4), dehydrated, embedded in paraffin, and sectioned (5 µm thickness). One section in each part of the ovary was stained with hematoxylin and eosin (HE), and then examined under a microscope (Nikon 80i, Tokyo, Japan) for the presence of different classes of follicles, including primordial follicles, primary follicles, secondary follicles, and antral follicles; their numbers were quantified as previously described [25]. The primordial, primary, and secondary follicles with visible nuclei were counted, and those without nuclei were not counted.…”

“…The primordial, primary, and secondary follicles with visible nuclei were counted, and those without nuclei were not counted. However, antral follicles with diameters <1 mm, which were not easy to find in ovarian sections, were counted when present in visible oocytes even if they did not have a visible nucleus (Figure 1) [25]. For primordial, primary, and secondary follicles, only those with a visible nucleus were counted (); those without a nucleus were not counted (×).…”