This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Grimard, B. Articles by Thibier, M. Search for Related Content PubMed Articles by Grimard, B. Articles by Thibier, M.

Influence of postpartum energy restriction on energy status, plasma LH and oestradiol secretion and follicular development in suckled beef cows

Effects of postpartum energy restriction, parity and time after parturition on energy status (measured by glucose, insulin, non-esterified fatty acids (NEFAs) and β-hydroxybutyrate), LH secretion and follicular growth were investigated in ten primiparous and nine multiparous suckled cows. Females were allocated by parity, body mass and body condition score at calving to diets supplying either 100% (CE, n = 10) or 70% (LE, n = 9) of energy requirements until day 70 postpartum. Metabolic parameters were measured every week from calving to day 70 postpartum. Blood samples were collected at intervals of 15 min for 10 h on day 30 and day 50 after parturition for LH measurement. Ovaries were examined between days 20 and 30 and days 40 and 50 postpartum by ultrasonography. Energy supply affected mean plasma concentrations of glucose (CE: 0.64 ± 0.01 g l^–1 versus LE: 0.61 ± 0.01 g l^–1; P < 0.05) and NEFA (CE: 168 ± 17 µeq l^–1 versus LE: 309 ± 18 µeq l^–1; P < 0.01) but by day 70 postpartum, glucose and NEFA concentrations were not significantly different between the two groups. LH pulse amplitude and frequency were not affected by energy supply (P > 0.10). However, at day 30 postpartum, LH pulse frequency was negatively correlated with plasma concentration of NEFA (r= –0.61; P < 0.01). Cows fed diets supplying 100% of energy requirements had more large follicles than did cows fed low energy diets (CE: 0.82 ± 0.05 versus LE: 0.31 ± 0.05; P < 0.05). The size of the largest follicle was greater in CE cows than in LE cows (CE: 10.2 ±0.1 mm versus LE: 8.7 ± 0.2 mm; P < 0.05). Between 40 and 50 days postpartum, the size of the largest follicle was negatively correlated with NEFA concentration (r= –0.5; P < 0.05). These results suggest that LH pulse frequency might be affected by energy supply when energy balance was strongly negative, whereas follicular growth was affected at a later stage, after parturition.