Effects of Restriction of Dietary Energy Intake during the Prepubertal Period on Secretion of Luteinizing Hormone and Responsiveness of the Pituitary to Luteinizing Hormone-Releasing Hormone in Heifers

Day, M. L.; Imakawa, Kazuhiko; Zalesky, D. D.; Kittok, R. J.; Kinder, J. E.

doi:10.2527/jas1986.6261641x

Cited by 123 publications

(85 citation statements)

References 6 publications

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“…Entretanto, a função reprodutiva é limitada em condições de restrição nutricional, como a observada neste trabalho. De acordo com Day et al (1986), a restrição do nível energético deprime o eixo hipófise-hipotalâmico, o que diminui a atividade ovariana. Desta maneira, supõe-se que até mesmo novilhas púberes diminuíram a atividade cíclica, o que proporcionou baixa TP para estas fêmeas.…”

Section: Resultsunclassified

Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano

Montanholi

Barcellos

Borges

et al. 2004

Pesq. agropec. bras.

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O objetivo deste trabalho foi avaliar os efeitos da intensidade do ganho de peso no período de recria, dos 13 aos 18 meses de idade, sobre a taxa de prenhez de novilhas de corte acasaladas com o sobreano durante o outono. Os tratamentos foram constituídos de 30 novilhas com peso médio de 208 kg, submetidas a ganho médio de 0,595 kg dia-1 (G600), 41 novilhas com peso médio de 197 kg submetidas a ganho médio de 0,656 kg dia-1 (G700) e 58 novilhas com peso médio de 181 kg submetidas a ganho médio de 0,723 kg dia-1 (G800). Foram avaliados os efeitos dos tratamentos sobre peso, escore de trato reprodutivo e taxa de prenhez. As taxas de prenhez foram 30,0% 47,8% e 50,0% para os grupos G600, G700 e G800, respectivamente, não existindo diferença significativa entre os grupos. Os grupos G700 e G800, submetidos à maior taxa de ganho de peso, apresentaram maiores valores de escore de trato reprodutivo em relação ao G600 no início da estação de monta. Novilhas com escores mais elevados apresentaram tendência a maior taxa de prenhez. A taxa de prenhez esteve associada à intensidade de ganho de peso na recria independentemente das variações de peso no acasalamento.

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Section: Resultsunclassified

Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano

Montanholi

Barcellos

Borges

et al. 2004

Pesq. agropec. bras.

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“…Numerous studies have demonstrated a close association between body growth, nutritional status and the timing of puberty onset. In cattle [4,5], sheep [6,7] and rodents [8,9], energy deficiency retards growth and delays the onset of puberty. Several lines of evidence from earlier investigations…”

Section: Introductionmentioning

confidence: 99%

Body Growth and Plasma Concentrations of Metabolites and Metabolic Hormones during the Pubertal Period in Female Shiba Goats

Sakurai

Ohkura

Matsuyama

et al. 2004

Journal of Reproduction and Development

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Abstract.It has been shown in various species that the onset of puberty is closely associated with body growth and nutritional state rather than age. The present study was conducted to determine the timing of puberty and to clarify body growth and metabolic changes around the pubertal period in female Shiba goats. Blood samples were collected between 10 to 38 weeks of age from 12 female goats, and plasma concentrations of progesterone, metabolites (glucose, nonesterified fatty acid, ketone body and acetic acid) and metabolic hormones (insulin and insulin-like growth factor-I (IGF-I)) were analyzed. Physical parameters (body weight, withers height and body length) were also measured at the blood sampling. The week when plasma progesterone concentrations first exceeded 1.0 ng/ml was designated as the onset of puberty. The results showed that the average age of the onset of puberty was 27.0 ± 0.9 (mean ± SEM) weeks in female Shiba goats. When the goats reached puberty, the average values of body weight and goat body mass index ((body weight (kg)/withers height (cm)/body length (cm)) × 10 3 ) were 12.2 ± 0.5 kg and 5.7 ± 0.2, respectively. No particular change associated with puberty was apparent for plasma concentrations of the metabolites examined. Plasma insulin concentrations were maintained at lower levels until the onset of puberty, and then they began to gradually increase. Plasma IGF-I concentrations began to gradually increase 1 to 4 weeks before the onset of puberty and this increase continued throughout the peripubertal period. These results imply that IGF-I acts as a peripheral nutritional signal to trigger the onset of puberty in Shiba goats. Key words: Puberty, Body growth, Metabolites, IGF-I, Shiba goat (J. Reprod. Dev. 50: [197][198][199][200][201][202][203][204][205] 2004) he onset of puberty is the result of a series of complex developmental events that occur within the reproductive endocrine axis. Just before the onset, there is a high frequency rhythm of gonadotropin-releasing hormone (GnRH) secretion and a sustained rise in basal luteinizing hormone (LH) secretion as the frequency of LH pulses increases, and the follicular phase begins, leading to the first LH surge and ovulation [1]. It has also been shown in heifers that the responsiveness of the pituitary gland to GnRH [2] and the action of estrogen on LH secretion [3] also change just before puberty. Numerous studies have demonstrated a close association between body growth, nutritional status and the timing of puberty onset. In cattle [4,5], sheep [6,7] and rodents [8,9], energy deficiency retards growth and delays the onset of puberty. Several lines of evidence from earlier investigations

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“…Changes in body condition, direction of body weight change and intake of dietary energy influence the duration of anoestrus after parturition (Wiltbank et al, 1962;Dunn & Kaltenbach, 1980) and during the prepubertal period in bovine females. Nutri¬ tionally induced anoestrus or a delay in the onset of puberty in heifers that results from feeding them diets with low energy content is mediated by a suppression of luteinizing hormone (LH) in the circulation (Imakawa et ai, 1986;Day et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

Circulating gonadotrophins during a period of restricted energy intake in relation to body condition in heifers

Roberson

Stumpf²,

Wolfe³

et al. 1992

Reproduction

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Effects of Restriction of Dietary Energy Intake during the Prepubertal Period on Secretion of Luteinizing Hormone and Responsiveness of the Pituitary to Luteinizing Hormone-Releasing Hormone in Heifers

Cited by 123 publications

References 6 publications

Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano

Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano

Body Growth and Plasma Concentrations of Metabolites and Metabolic Hormones during the Pubertal Period in Female Shiba Goats

Circulating gonadotrophins during a period of restricted energy intake in relation to body condition in heifers

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