RESUMEN
The objective of this study was to determine the effect of a rumen-protected fish oil supplement on the production and reproduction variables in postpartum dairy cows. Holstein cows (n=46) were given a basal total mixed diet plus one PUFA supplement: n-3 (n-3; protected fish oil; 1% dry matter intake (DMI); n=23) or control (n-6; toasted soybeans; 1.8% DMI; n=23), in a switchback design over two consecutive lactations. Supplements were added to the diet between calving and 2 months after calving to assess the effect on growth and maturation of ovarian follicles from which ovulation occurred around the day of insemination. Body weight (BW), milk yield (MY) and composition, dry matter intake (DMI), energy balance (EB), subcutaneous fat thickness, plasma fatty acid composition, plasma nonesterified fatty acids (NEFA), glucose and urea concentrations, follicular activity, embryo mortalities and fertility (conception rate after first AI, AI1) were assessed. BW, MY, DMI, plasma NEFA, glucose and urea were unaffected by the diet. There was a trend of an increased number of large follicles (diameter≥10mm) with the n-3 dietary supplementation (P=0.06) and a decrease in infertility or early embryo mortality rate 21 days after AI, 13.5% in the n-3 compared with 38.8% in the n-6 group (P=0.09), with no effect on the conception rate at 35d or 90d after AI1. These data suggest that the effect seen on ovarian variables is not associated with an effect on production and metabolic variables and is specific to n-3 PUFA supplementation. Further studies are necessary to determine whether DHA or EPA enhances fertility in lactating dairy cattle.
Asunto(s)
Alimentación Animal/análisis , Bovinos/fisiología , Dieta/veterinaria , Ácidos Grasos Omega-3/farmacología , Lactancia/efectos de los fármacos , Reproducción/efectos de los fármacos , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Composición Corporal , Bovinos/sangre , Suplementos Dietéticos , Ácidos Grasos Omega-3/administración & dosificación , Ácidos Grasos Omega-3/química , Femenino , Aceites de Pescado/administración & dosificación , Aceites de Pescado/química , Leche/química , Grasa Subcutánea/efectos de los fármacos , Grasa Subcutánea/fisiologíaRESUMEN
The major limitation to the development of embryo production in cattle is the strong between-animal variability in ovulatory response to FSH-induced superovulation, mainly due to differences in ovarian activity at the time of treatment. This study aimed to establish whether anti-Müllerian hormone (AMH) was an endocrine marker of follicular populations in the cow, as in human, and a possible predictor of the ovarian response to superovulation. Anti-Müllerian hormone concentrations in plasma varied 10-fold between cows before treatment and were found to be highly correlated with the numbers of 3- to 7-mm antral follicles detected by ovarian ultrasonography before treatment (r=0.79, P<0.001) and the numbers of ovulations after treatment (r=0.64, P<0.01). Between-animal differences in AMH concentrations were found to be unchanged after a 3-mo delay (r=0.87, P<0.01), indicating that AMH endocrine levels were characteristic of each animal on a long-term period. The population of healthy 3- to 7-mm follicles was the main target of superovulatory treatments, contained the highest AMH concentrations and AMH mRNA levels compared with larger follicles, and contributed importantly to AMH endocrine levels. In conclusion, AMH was found to be a reliable endocrine marker of the population of small antral gonadotropin-responsive follicles in the cow. Moreover, AMH concentrations in the plasma of individuals were indicative of their ability to respond to superovulatory treatments.