Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1322586535.pdf (1.79 MB)

ETD Abstract Container

Abstract Header

Nutritional Regulation of Precocious Puberty in Heifers

Maquivar, Martin G.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1322586535

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Animal Sciences.
Feeding a high energy diet to weaned heifers hastens sexual maturation and puberty. Two experiments were designed to study the metabolic, reproductive and molecular responses that lead to precocious puberty. The first experiment aimed to test the influence of a high energy diet with either high starch (46.4%, n = 10) or low starch content (14.48%, n = 12) versus a lesser energy diet, (control, 19.03% starch, n = 11) on age at puberty and on hormone concentrations. Precocious puberty was induced in 42% and 60% of heifers in the low and high starch diets, but none fed the control diet. The high energy diets increased IGF-I concentrations over the control diet. Heifers experiencing precocious puberty on the high energy diets had greater (P < 0.05) IGF-I concentrations, but not GH concentrations. Results strongly suggest that energy content of the diet is more critical than starch composition to induce precocious puberty and a link between IGF-I and the occurrence of precocious puberty exists. The second study sought to evaluate the impact of the high energy diet on estrogenic capacity and gene expression within the dominant follicle, and its relationship to estradiol and LH concentrations. Within treatments (high energy with high starch content, HIGH; and roughage-based control, CONT), heifers were assigned to be ovariectomized (OVX), or to remain intact (INT) for assessment of secretion of LH and age at puberty. Overall ADG (all heifers) was greater (P < 0.01) in HIGH heifers (1.57 ± 0.71 kg/d) than CONT (1.21 ± 0.74 kg/d). BW of the HIGH heifers was greater (P < 0.05) than CONT at 186 d of age and thereafter. Age at puberty was different (P < 0.05), 194.33 ± 8.95 d HIGH-INT and 253.75 ± 1.25 d CONT-INT, and BW at puberty (P < 0.02), 257.7 ± 17.02 kg HIGH-INT and 321.67 ± 11.65 kg CONT-INT. No differences (P > 0.05) were observed at age at puberty in the OVX sub treatments, 235.25 ± 11.9 d HIGH-OVX and 219.66 ± 10.9 d CONT-OVX and a tendency (P = 0.07) for BW at puberty, 329.07 ±.13.17 kg HIGH-OVX and 285.43 ± 14.08 kg CONT-OVX. Mean LH concentrations were greater (P < 0.05) in the HIGH-INT than CONT-INT treatment at 170 and 208 days of age. Neither frequency nor amplitude of LH pulses differed between treatments. Expression of mRNA for insulin-like growth factor-I receptor (IGF-IR), luteinizing hormone receptor (LHR), cholesterol side-cleavage chain (CYP11A1) and aromatase (CYP19A1) were not affected by treatment. Intra-follicular fluid concentration of estradiol and progesterone was similar among treatments. In conclusion, the HIGH dietary treatment increased BW and LH secretion resulting in earlier age at puberty. Incidence of precocious puberty did not differ between treatments. Intra-follicular concentrations of estradiol and progesterone nor steroidogenic enzyme expression differed between treatments. It is plausible that heifers in both diets received signals that precociously activated the reproductive axis. Further research is needed to determine the involvement of IGF-I in the maturation of the reproductive axis.
Michael Day (Advisor)
Steve Loerch (Committee Member)
Kichoon Lee (Committee Member)
Joseph Ottobre (Committee Member)
Alexandre Pires (Committee Member)
159 p.
Animal Sciences
IGF-I; precocious puberty; Bos taurus; ovarian activity

Recommended Citations

Citations

  • Maquivar, M. G. (2011). Nutritional Regulation of Precocious Puberty in Heifers [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322586535

    APA Style (7th edition)

  • Maquivar, Martin. Nutritional Regulation of Precocious Puberty in Heifers. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1322586535.

    MLA Style (8th edition)

  • Maquivar, Martin. "Nutritional Regulation of Precocious Puberty in Heifers." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322586535

    Chicago Manual of Style (17th edition)

osu1322586535
2,185
© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.