Effects of nutrition and season on the onset of puberty in the beef heifer

Abstract

Age at puberty is a major determinant of lifetime reproductive efficiency of beef cows. Research conducted during the past 20 yr has documented the major endocrine events leading to first ovulation in heifers. The critical event seems to be a prepubertal increase in pulsatile LH secretion. Environment influences timing of puberty onset in beef heifers. Nutrition and season are two of the better-defined variables that have been studied. Age at puberty is related inversely to plane of nutrition. The effect of nutrition on sexual maturation involves effects on timing of the prepubertal increase in LH secretion and seems to involve the LH pulse generating system located in the hypothalamus. The precise mechanism by which nutrition influences pulsatile LH secretion has not been elucidated, but signals reflecting metabolic status seem to be involved. Seasonal conditions of the early (birth to 6 mo of age) and late (6 to 12 mo of age) postnatal periods also influence timing of puberty onset in the heifer. Autumn-born heifers attain puberty at younger ages than do spring-born heifers, and exposure to spring-summer temperatures and photoperiods during the second 6 mo of life reduces age at puberty regardless of season of birth. Photoperiod may be the major seasonal cue that influences puberty onset in cattle. Limited evidence suggests that melatonin, a pineal hormone, is involved with transducing photic stimuli into neuroendocrine signals that influence LH secretion. If the physiological mechanisms mediating the effects of nutrition and season on timing of puberty onset are determined, then management strategies for reducing age at puberty can be enhanced.

Effect of milk replacer and rumen inert fat on growth and reproduction of Malpura ram lambs

“…However, in the present study, we could not find any significant effect of improved feeding on puberty age in the Malpura ram lambs, possibly owing to achievement of critical weight by ram lambs required for attainment of puberty in both the groups, as the growth rate has little effect on the rate of sexual maturation after a certain critical weight has been achieved (Schillo et al, 1992).…”

Metabolic changes in early lactation and impaired reproductive performance in dairy cows

“…The establishment of LH pulsatility is responsible for the initiation of cyclicity in, for example, pubertal heifers [82]. The inhibition of LH pulsatility before puberty, and consequently the inhibition of ovarian cyclicity, is in these animals probably due to a negative feedback by estradiol secreted by the ovary.…”

“…The inhibition of LH pulsatility before puberty, and consequently the inhibition of ovarian cyclicity, is in these animals probably due to a negative feedback by estradiol secreted by the ovary. Among the factors that are associated with onset of puberty, attainment of a critical level of body fat is important [82]. This strongly suggests that there are links between the reproductive endocrine system and metabolic status of the animal, which could also apply to non-adaptive cows in early lactation.…”

Creep-feeding to stimulate metabolic imprinting in nursing beef heifers: impacts on heifer growth, reproductive and physiological variables

“…Age at puberty in cattle is highly influenced by nutritional status and body development (Schillo et al, 1992). Hence, nutritional interventions that improve nutrient utilization, body fat accretion, and increase circulating concentrations of hormones that facilitate the puberty process, such as IGF-I and leptin, are known to hasten puberty attainment in heifers (Williams et al, 2002; Cooke et al, 2008).…”

“…(1) puberty in cattle is highly influenced by nutritional status and body development (Schillo et al, 1992), including growth rate, body fat accretion, and circulating concentrations of hormones associated with nutrient metabolism and lipogenesis such as IGF-I and leptin (Williams et al, 2002;Cooke et al, 2008), and (2) management systems that stimulate metabolic imprinting enhance nutrient metabolism and body fat accretion in cattle (Graugnard et al, 2010;Scheffler et al, 2014;Moriel et al, 2014a). Supporting our rationale, Moriel et al (2014b) reported reduced age and BW at puberty in heifers weaned at 72 days of age and fed a high-concentrate diet for 90 days compared with forage-fed cohorts weaned at 252 days of age.…”