Effects of early lactation body condition loss in dairy cows on serum lipid profiles and on oocyte and cumulus cell transcriptomes.

The objective of this study was to determine the effect of early lactation body condition (BC) loss in multiparous dairy cows on serum lipids and the effect of these changes on oocyte and cumulus cell transcriptomes. Body condition loss in dairy cattle after parturition is associated with reduced fertility and increased pregnancy loss. The complex interplay between BC, nutrition, dry matter intake, milk production, and time of calving has presented a barrier to understanding mechanisms leading to reduced fertility. We identified cows that lost BC (L group; n = 10) or maintained or gained BC (M/G group; n = 8) during the first 27 to 33 d in milk and investigated changes in serum fatty acids and oocyte and cumulus cell transcriptomes at 75 to 81 d in milk. The L group had increased serum levels of nonesterified fatty acids and mead acid, and reduced serum levels of petroselaidic acid and behenic acid. Transcriptome analyses revealed 38 differentially expressed genes (DEG) in oocytes and 71 DEG in cumulus cells of L (n = 3) compared with M/G group (n = 3). Network analysis connected serum fatty acid changes to downstream effects including reduced inflammatory response and mitochondrial membrane depolarization, increased production of reactive oxygen species, and functions related to fatty acid metabolism and cytoplasmic organization in oocytes. These effects were associated with predicted effects on signaling in oocytes through calcium, insulin, O-GlcNAcase (OGA), fibroblast growth factor receptor 4 (FGF4R), peroxisome proliferator activated receptor gamma coactivator 1 α (PPARGC1A), and phospholipase D2 (PLD2) pathways, with a connection to the cumulus cell via calcium signaling. These results connect BC loss following parturition to changes in serum lipid levels, and changes potentially affecting oocyte quality; thus, these results provide new insight into mechanism of reduced fertility.

Pregnancy rates and serum 13,14-dihydro-15-keto-PGF2α concentrations in recipient Nelore heifers treated with meloxicam after the transfer of in vitro-produced embryos.

This study aimed to determine if the administration of meloxicam, a cyclooxygenase 2 inhibitor, to Nelore (Bos taurus indicus) heifers, in which embryo transfer is more difficult and requires a greater manipulation of the reproductive tract than in Bos taurus females, would improve the pregnancy rates by decreasing serum PGFM concentrations. After estrous synchronization, multiparous recipient heifers (n = 85) were selected as embryo recipients and were randomly allocated into two groups: CON (n = 42), the control group, in which animals received 10 mL of saline intramuscularly (the same volume of meloxicam), and MEL (n = 43), the group in which animals were treated with meloxicam. According to the degree of passing the catheter, recipients from both groups were classified as grade I (easy; <80 seconds) and grade II (difficult; >80 seconds). One hour before embryo transfer, MEL recipients received an injection of 200 mg of meloxicam. Blood samples were collected from all heifers 1 hour before embryo transfer and 4 and 8 hours after embryo transfer to determine the serum concentrations of 13,14-dihydro-15-keto-PGF2α (PGFM), a PGF2α metabolite. A significant difference in the pregnancy rates on Day 30 was observed in MEL animals between those classified as grade I and II (90.48% vs. 54.54%, respectively; P < 0.01). Considering the animals from CON, the pregnancy rates were similar between grades I and II. Serum concentrations of PGFM from samples collected 4 and 8 hours after embryo transfer were lower in pregnant animals from MEL grade I than in pregnant animals from MEL grade II. Considering the pregnant females from CON, no difference was observed from samples collected 4 and 8 hours after embryo transfer. Interestingly, no difference in PGFM serum concentrations was observed between the pregnant females from MEL grade II and pregnant females from CON (P < 0.05). Thus, we conclude that meloxicam had a positive effect on the pregnancy rates of grade I Nelore heifers.

Artificial activation of bovine and equine oocytes with cycloheximide, roscovitine, strontium, or 6-dimethylaminopurine in low or high calcium concentrations.

Knowledge on parthenogenetic activation of oocytes is important to improve the efficiency of nuclear transfer (NT) and intracytoplasmic sperm injection (ICSI) because artificial activation of oocyte (AOA) is an essential step to achieve embryo production. Although different procedures for AOA have been established, the efficiency of in vitro production of embryos remains low, especially in equines and Bos taurus bovines. In an attempt to improve the techniques of NT and ICSI in bovine and equine species, we tested different combinations of drugs that had different mechanisms of action for the parthenogenetic activation of oocytes in these animals. The oocytes were collected, in vitro matured for 24 to 30 h and activated artificially, in the presence of low or high concentrations of calcium, with combinations of calcium ionophore (ionomycin) with cycloheximide, roscovitine, strontium, or 6-dimethylaminopurine (6-DMAP). For assessment of activation rates, oocytes were stained with Hoechst 33342 and observed under an inverted microscope. We showed that all combinations of drugs were equally efficient in activating bovine oocytes, with the best results obtained when high concentrations of calcium were adopted. For equine oocytes, high concentrations of calcium were not beneficial for the parthenogenetic activation and the combination of ionomycin with either 6-DMAP or roscovitine was effective in inducing artificial activation of oocytes. We believe that our preliminary findings provide some clues for the development of a better AOA protocol to be used with these species.