DVM, Departamento de Reproducción, Facultad de Veterinaria, INIA La Estanzuela, MSc, Colonia, PhD
Taurus, Bs. As 01/2010; 12:24-34.
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Available from: Daniel Cavestany, Sep 29, 2015
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    ABSTRACT: Control of metabolism during pregnancy and lactation involves two types of regulation-homeostasis and homeorhesis. Homeostasis control involves maintenance of physiological equilibrium or constancy of environmental conditions within the animal. Homeorhesis is the orchestrated or coordinated control in metabolism of body tissues necessary to support a physiological state. Regulation of nutrient partitioning during pregnancy involves homeorhetic controls arising from the conceptus. This assures growth of the conceptus (fetus and fetal membranes) and gravid uterus as well as development of the mammary gland. With the onset of lactation many--perhaps even most--maternal tissues undergo further adaptations to support rates of lipogenesis and lipolysis in adipose tissue are examples of important homeorhetic controls of nutrient partitioning that are necessary to supply mammary needs for milk synthesis. The interactions between homeorhesis and homeostasis during pregnancy and lactation and possible endocrine control are discussed. While not definitively established, roles for placental lactogen and prolactin are attractive possibilities in homeorhetic regulation of maternal tissues to support pregnancy and the initiation of lactaion, respectively.
    Journal of Dairy Science 10/1980; 63(9):1514-29. DOI:10.3168/jds.S0022-0302(80)83111-0 · 2.57 Impact Factor
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    ABSTRACT: The objectives of this study were to characterize early postpartum (PP) follicular development in dairy cows and to evaluate the influence of energy balance (EB) and the level of dietary fat on dominant follicle development and function. Forty-five multiparous Holstein cows were fed either low (LF, 3.3%), moderate (MF, 5.2%), or high (HF, 7.1%) total dietary fat beginning at parturition, and daily EB was determined for all cows. Follicular development was monitored by ultrasonography, and blood plasma was analyzed for metabolites, metabolic hormones, progesterone, estradiol, and FSH. After an increase (p < 0.01) in mean plasma FSH during Days 1-5, all cows experienced a wave of follicular development during the second week PP regardless of diet or EB. Feeding the MF (p < 0.05) or HF (p < 0.06) diet resulted in a greater number of class IV (> 15 mm) follicles on Day 14 PP as compared to the LF diet. Cows fed the MF diet had higher (p < 0.05) peak plasma estradiol during the first follicular wave and a shorter (p < 0.05) interval to first ovulation than both LF and HF cows. Follicular development prior to first ovulation was characterized by either ovulation of the first dominant follicle (OV, n = 19), one or more waves of nonovulatory dominant follicles (NOV, n = 18), or the formation of a follicular cyst (CYST, n = 8). Ovulation failure during the first follicular wave PP was accompanied by lower (p < 0.001) peak plasma estradiol (0.96 +/- 0.36 vs. 5.0 +/- 0.35 pg/ml), a smaller (p < 0.01) maximum follicle diameter (16.0 +/- 0.9 vs. 20.0 +/- 1.0 mm), lower (p < 0.09) levels of plasma insulin-like growth factor-I (IGF-I; 73.5 +/- 10.1 vs. 102.9 +/- 9.9 ng/ml), and a longer (p < 0.02) interval to the EB nadir (14.6 +/- 1.9 vs. 6.4 +/- 1.9 days). The number of days to first ovulation was positively correlated with days to the EB nadir (r = 0.55), with dominant follicles that emerged after the EB nadir exhibiting enhanced (p < 0.01) production of estradiol and greater (p < 0.01) ovulatory success. The development of large (> 10 mm) dominant follicles was not a limiting factor in PP reproductive recovery, and moderate dietary fat shortened the interval to first ovulation. Follicular competence early PP was associated with higher plasma IGF-I and a shorter interval to the EB nadir.
    Biology of Reproduction 01/1997; 56(1):133-42. DOI:10.1095/biolreprod56.1.133 · 3.32 Impact Factor
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    ABSTRACT: The objectives of this study were to relate energy balance and metabolic hormones during the early postpartum period in dairy cows with dominant follicle development before first ovulation and to evaluate the effects of prilled lipid on follicular development during the first follicular wave after parturition and the postpartum anovulatory interval. At parturition, 42 cows received a control diet (4.8% fat) or a diet supplemented with prilled fatty acids (7.0% fat). Energy balance was determined daily. Ovarian follicular development was monitored by ultrasonography, and blood plasma or serum was analyzed for estradiol, progesterone, and metabolic hormones. Dry matter intake was lower in cows supplemented with dietary lipids during the first 4 wk of lactation, but energy intake, energy balance, and the postpartum anovulatory interval were similar between diets. A wave of follicular development occurred in all cows during the 2nd wk postpartum, and 50% of all cows ovulated their first dominant follicle. Numbers of follicles that were 3 to 5 mm, 6 to 9 mm, and 10 to 15 mm on d 8 postpartum were similar between diets and unrelated to energy balance or metabolic hormones. Diameter of the dominant follicle during d 8 to 14 postpartum and maximum diameter of the first-wave ovulatory follicle did not differ between diets. Cows with nonovulatory first-wave dominant follicles had lower mean plasma concentrations of estradiol during d 8 to 14 postpartum, a longer interval to the day of the energy balance nadir, lower serum concentrations of IGF-I, and higher 4% FCM yield than did cows with ovulatory first-wave dominant follicles. Serum IGF-I during d 1 to 13 was positively correlated with plasma estradiol during d 8 to 14 postpartum. Possibly because of reductions in dry matter intake, the consumption of prilled lipid by dairy cows during early lactation may be ineffective in altering energy balance, follicular development, and the postpartum anovulatory interval. Ovulation failure of dominant follicles early in the postpartum period is associated with greater production of 4% fat-corrected milk, a delayed energy balance nadir, and reduced concentrations of peripheral IGF-I.
    Journal of Dairy Science 02/1998; 81(1):121-31. DOI:10.3168/jds.S0022-0302(98)75559-6 · 2.57 Impact Factor
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