title: Dietary energy source and feeding levels during the rearing period affect ovarian follicular development and oocyte maturation in gilts.
abstract: Fifty-four Landrace x Yorkshire gilts (59.0 +/- 4.2 kg and 147 +/- 3 d old) were used to examine the effects of dietary energy source (starch or mixed fat) at high [112.5% of energy requirements recommended by NRC (1998)], normal (100%), and low (87.5%) energy feeding levels on ovarian follicular development and oocyte maturation. Forty-seven estrus gilts were slaughtered at Day 19 after the second estrus; oocytes were recovered from follicles >4 mm in diameter, and matured in vitro for 44 h. Gilts fed high-energy diets had more follicles >4 mm (mean, 25.8 vs. 19.1, P < 0.05) and more oocytes that reached metaphase II (80.3 vs. 64.0%, P < 0.05) than those fed the low-energy diet. Furthermore, gilts fed starch-rich diets had enhanced oocyte nuclear maturation relative to those fed fat-rich diets (75.4 vs. 68.0%, P < 0.05). Compared to the lower-energy feeding groups, high-energy feeding groups had higher (P < 0.05) blood concentrations of postprandial insulin (1562.4 vs. 990.0 ng/4 h), IGF-I (321.2 vs. 256.9 ng/mL), and LH pulses (2.7 vs. 1.4 pulses/6 h). Follicular fluid concentrations of IGF-I (198.5 vs. 143.1 ng/mL) and estradiol (152.6 vs. 124.8 ng/mL) were higher (P < 0.05) in the high-energy group than in the normal group. Compared with gilts fed the high-energy diet supplemented with fat, gilts fed the high-energy diet supplemented with starch had a tendency (P < 0.10) towards increased IGF-I concentration in both blood and follicular fluid, and improved oocyte nuclear maturation during culture in vitro. We inferred that starch-rich, high-energy diets during rearing may improve ovarian follicular development and oocyte maturation in replacement gilts.
authors.affiliation: Key Laboratory for Animal Disease Resistance Nutrition of the Ministry of Education of China, Institute of Animal Nutrition, Sichuan Agricultural University, Ya'an, China.
authors.forename: D S
authors.initials: DS
authors.lastname: Zhou
authors.forename: Z F
authors.initials: ZF
authors.lastname: Fang
authors.forename: D
authors.initials: D
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Zhuo
authors.forename: S Y
authors.initials: SY
authors.lastname: Xu
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Wang
authors.forename: P
authors.initials: P
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
mesh_terms: D000821:Animal Feed; D000818:Animals; D004032:Diet; D005260:Female; D020869:Gene Expression Profiling; D009865:Oocytes / Q000254:growth & development*; D006080:Ovarian Follicle / Q000254:growth & development*; D013552:Swine / Q000254:growth & development*