The current study was carried out to examine the effects of dry period duration on NEFA and IGF-I
plasma concentrations and postpartum ovarian activity resumption in dairy cows. Twenty-five pregnant
Friesian cows (second and third lactation) were randomly assigned to one (standard dry period, 9 weeks,
group C, n=12) of two (short dry period, 5 weeks, group T, n=13) treatments. Blood samples for NEFA
and IGF-I analyses were collected once a week during the last 5 weeks prepartum and the first 14 weeks of
lactation. Milk whey collection (twice/week) for progesterone analysis began 2 weeks after parturition and
was used to detect ovarian activity resumption (at least three consecutive samples with P4≥300 pg/mL).
The data obtained were analyzed by ANOVA for repeated data (mixed) and GLM of the SAS statistical
package. Short dry periods reduced milk production (26.55 vs. 27.55 kg/d; P≤0.01), without modifying
milk quality. The mean interval from calving to first postpartum cycle was shorter in group T than in
group C (34.5 vs. 46.9 d, P≤0.01). No differences were found in NEFA plasma concentrations between
groups either before or after calving, while IGF-I circulating concentrations were higher in group T than in
group C during both the dry period and the first 14 weeks of lactation (P≤0.01). In conclusion, the
reduction in the dry period had a positive impact on metabolic balance and time of postpartum resumption
of ovarian activity.
