Efectos de la suplementación con acacia negra (Acacia mearnsii) sobre la actividad ovárica, la involución uterina y los perfiles hormonales en vacas lecheras en condiciones de altura

Abstract

The feeding program carried out during the pre-partum and post-partum period in dairy cows is crucial to preserve their reproductive performance. The goal of the present study was to assess the effect of black wattle (Acacia mearnsii) supplementation on ovarian activity, uterine involution, and hormone profiles in dairy cows maintained at high-altitude conditions. A total of 10 Holstein dairy cows were divided into 2 groups: control (C; n=5) and supplemented group (AM; n=5). A dehydrated black wattle (AM; Acacia mearnsii) supplement was administered to AM group and adjusted to 22% crude protein per animal (Dehydrated Supplement; MS= 2.7 kg AM/day per cow, ~20% of total DM). Body weight (BW) was recorded individually in different periods (day 15 pre-partum, and day 19, 34, and 49 post-partum). Ovarian [follicles (FL), corpora lutea (CL)] and ovarian diameter (OD; mm)] and uterine structures [uterine horn thickness (HT; mm), cervix length (CrL; cm) and diameter (CD; cm), and uterine involution %] were assessed till day 34 postpartum. Moreover, hormone profiles such as thyroid-stimulating hormone (TSH; IU/mL), follicle-stimulating hormone (FSH; IU/mL), luteinizing hormone (LH; IU/mL), and progesterone (P4; ng/mL) were measured till day 49. Statistical differences were observed in BW when day 15 prepartum was compared to day 19 postpartum (p=0.05). However, no differences were observed between C and AM group regarding BW within each timepoint (p>0.05). No changes were observed in FL over time irrespective of the group studied (p<0.05). However, FL was significantly different when C and AM group were compared within each time-point (p< 0.05). Although no significant differences were observed on day 5 post- partum regarding the number of CL, significant differences were observed on day 25 and day 34 postpartum between groups (p> 0.05). OD increased from day 5 to Day 35 post-partum irrespective of the group assessed and differ between groups within time-points (p< 0.05). Differences were observed in TSH within day 19 and day 49 post-partum (p< 0.05). FSH was statistically different between groups on day 19 post-partum (p< 0.05). LH was more variable than TSH and FSH among and within time-points and groups (p< 0.05). Differences were observed between groups regarding P4 within day 19 and 49 post-partum (p< 0.05). In conclusion, overall although no differences were observed in BW between groups or time-points, the supplementation with AM showed differential patterns in reproductive tract structures/dimensions and hormone levels in dairy cows maintained at high-altitude conditions