The present study analysed the response of adult female capybaras (Hydrochaeris hydrochaeris) to different dietary supplementation in relation to litter size per parturition and oestradiol secretion profile during pregnancy and the oestrous cycle. All four experimental groups received 'camerum' grass (Pennisetum purpureum) and water ad libitum and three of the groups were also fed a protein, lipid or protein and lipid supplement. Litter size per parturition did not show any significant

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... e among treatment groups, but was significantly higher (P < 0.05) than in the control group. There was no significant difference in oestradiol concentrations among treatments and the control group, during each phase of the oestrous cycle or during gestation. The average oestradiol concentrations in dioestrous, oestrous and metoestrous phases were not significantly different from each other, but were significantly lower (P < 0.05) than the average oestradiol concentration in the pro-oestrous phase. In addition, average oestradiol concentrations increased after the second gestation month, but were significantly higher (P < 0.05) only after the fourth gestation month, achieving maximum value by the end of gestation. Dietary supplementation had no significant effect on hormonal concentrations during the oestrous cycle and gestational period. However, an increase in litter size per parturition was observed among female capybaras that received dietary supplementation.