Effect of an Ovsynch56 protocol initiated at different intervals after insemination with or without a presynchronizing injection of gonadotropin-releasing hormone on fertility in lactating dairy cows.

The objectives of this study were to evaluate effects of 2 resynchronization protocols beginning at different intervals after artificial insemination (AI) on the pattern of return to estrus, ovarian responses, and pregnancy per AI (P/AI) to reinsemination. Lactating cows from 2 dairies, located in Texas (n=2,233) and Minnesota (n=3,077), were assigned to 1 of 4 timed AI (TAI) protocols 17 ± 3 d after AI. All cows were examined for pregnancy 31 ± 3 d after previous AI. Cows assigned to early Ovsynch56 (E-OV56) or OV56 received the Ovsynch56 protocol starting 24 or 31 d after AI, respectively. Cows assigned to early GnRH-GnRH-PGF(2α)-GnRH (E-GGPG) or GGPG received a presynchronizing GnRH injection 17 or 24 d after AI, respectively, 7 d before the start of the Ovsynch56 protocol. Cows observed in estrus after enrollment were inseminated on the same day. Ovaries were examined and blood was sampled for progesterone concentration on the day of first GnRH and PGF(2α) injection of the Ovsynch56 protocol. Pregnancy was diagnosed at 31 and 66 d after resynchronized AI. On the day of the first GnRH injection of the TAI, a higher percentage of cows on E-GGPG and GGPG protocols had a corpus luteum (E-GGPG=83.8, GGPG=91.2, E-OV56=80.4, and OV56=75.5%) and progesterone concentration >1 ng/mL (E-GGPG=62.5, GGPG=76.0, E-OV56=53.6, and OV56=60.8%) than cows assigned to other protocols. However, the percentage of cows ovulating to the first GnRH injection of TAI was not affected by treatment. Fewer E-GGPG and more OV56 cows were reinseminated in estrus (E-GGPG=23.7, GGPG=49.0, E-OV56=41.6, and OV56=57.6%). Treatment did not affect P/AI at 31 or 66 d for cows reinseminated in estrus. However, cows reinseminated in estrus had greater P/AI at 31 (40.0 vs. 27.5%) and 66 d (36.0 vs. 23.9%) than cows completing the TAI protocols. Among cows completing the TAI protocols, initiation of GGPG at 24 d after AI increased, whereas initiation of Ovsynch56 at 24 d after AI decreased P/AI at 31 d after reinsemination (E-GGPG=30.6, GGPG=28.3.0, E-OV56=22.3, and OV56=28.7%). Pregnancy per AI did not differ across treatment at 66 d after TAI (E-GGPG=26.6, GGPG=24.4, E-OV56=20.0, and OV56=24.1%). Overall, type of resynchronization protocol and protocol initiation time did not affect P/AI 66 d after reinsemination (E-GGPG=29.7, GGPG=30.5, E-OV56=26.1, and OV56=30.4%). In conclusion, GGPG resynchronization protocols and initiation of resynchronization protocol 24 d after AI reduced the number of cows reinseminated in estrus but neither the timing of initiation of resynchronization nor presynchronization with GnRH affected overall P/AI.

Effect of gonadotropin-releasing hormone or prostaglandin F(2α)-based estrus synchronization programs for first or subsequent artificial insemination in lactating dairy cows.

The objective was to evaluate the effects of GnRH or PGF(2α)-based synchronization and resynchronization programs on fertility in lactating dairy cows. For experiment 1, cows (n=1,521) were presynchronized with 2 injections of PGF given at 36 and 50 DIM and assigned to 1 of 3 protocols: Ovsynch [OVS; n=552; GnRH injection, PGF(2α) injection 7 d later, GnRH injection 56 h later, and timed artificial insemination (TAI) 16 h later] beginning at 14 d after presynchronization (PS), GnRH-GnRH-PGF(2α)-GnRH (GGPG; n=402) treatment with a GnRH injection given 7 d after PS and OVS 7 d later, or PGF(2α)-GnRH-PGF(2α)-GnRH (P7GPG; n=567) treatment with a PGF(2α) injection given 7 d after PS and OVS beginning 7 d later. Experiment 2 cows (n=2,327) were assigned to 1 of 3 resynchronization protocols 7 d before nonpregnancy diagnosis (NPD): GGPG cows (n=458) received a GnRH injection at enrollment and OVS at NPD; P7GPG cows (n=940) received a PGF(2α) injection at NPD and OVS 7 d later; and P11GPG cows (n=929) received a PGF(2α) injection 3 d after NPD and OVS 11 d later. In both experiments, cows were artificially inseminated upon estrus detection (ED). In experiment 1, 52.3% of cows were artificially inseminated upon ED, with GGPG having reduced ED (GGPG=46.8 vs. OVS=50.7 and P7GPG=57.7%). Treatments did not affect overall pregnancy per artificial insemination (P/AI) at 36 and 66 d after AI (OVS=34.1 and 32.3, P7GPG=34.6 and 31.9, and GGPG=31.3 and 28.1%, respectively) or pregnancy loss but cows artificially inseminated upon ED had higher P/AI than cows undergoing TAI (ED cows=37.9 vs. TAI cows=28.8%). Treatment did not affect P/AI for cows artificially inseminated upon ED or TAI at 36 and 66 d after AI (OVS=34.1 and 32.3, P7GPG=34.6 and 31.9, and GGPG=31.3 and 28.1%). Median days in milk at first AI was affected by treatment (P7GPG=59 vs. OVS=68 and GGPG=68 d). In experiment 2, GGPG reduced ED (GGPG=23.3 vs. P7GPG=74.9 and P11GPG=79.6%). Treatment did not affect overall P/AI at 36 and 66 d after AI (GGPG=29.2 and 25.8, P7GPG=28.7 and 26.6, and P11GPG=31.9 and 30.2%) or pregnancy loss. Cows artificially inseminated upon ED had greater P/AI than TAI cows (ED=32.3 and TAI=25.1%). However, treatment did not affect P/AI for cows artificially inseminated upon ED at 36 and 66 d after AI (GGPG=29.6 and 27.3, P7GPG=29.4 and 28.1, and P11GPG=35.7 and 33.7%) or TAI (GGPG=29.1 and 25.3, P7GPG=25.0 and 22.1, and P11GPG=16.9 and 16.9%). Median days between NPD and AI was affected by treatment (GGPG=10 vs. P7GPG=4 and P11GPG=7 d). Prostaglandin-based programs increased ED and reduced interval to first AI and between AI. Gonadotropin-releasing hormone-based programs increased the proportion of TAI cows. Cows artificially inseminated upon ED had increased P/AI compared with TAI cows.

Epoxide of diosgenin acetate synthesis: DoE for diastereoselective yield optimization, antimicroibial, antioxidant and antiproliferative effects.

Diosgenin and its derivatives have proved a huge importance in diverse biological activities. The optimized production of the diastereoisomers of the epoxide of diosgenin acetate by means of mCPBA is reported herein. This transformation had a previous design of experiments using the application of a statistical factorial DoE of 4 parameters (nk), where one variable is varied at a time, while others stay constant. The temperature showed the greatest effect on the reaction yield; so, at 298 K the diastereomeric ratio 3:1 of α and ß-epoxides, normally found, was raised to 1:1. Time was the second significant variable, but due to its high correlation with temperature, 30 min were required for a global 90% conversion at least. These diastereoisomers were characterized both isolated and in the mixtures obtained, to determine their antioxidant, antimicrobial and antiproliferative activity, finding a low antioxidant capacity by DPPH, but antimicrobial activity at the level of penicillin in gram negative bacteria by 1ß better to 1α. The antiproliferative capacity was higher for diastereoisomer ß, agreeing with the proportion of the mixture obtained by different conditions, increasing this in relation to the amount of this diastereoisomer present in hormone-dependent cancer cell lines such as Hela, PC-3 and MCF-7, with 10.0 µM obtained values of viability at 21.8 %, 35.8 % and 12.3 % respectively. DoE optimization allows to manipulate the ratio between diastereoisomers with the minimum number of experiments, extending the analysis of the effect of the ratio between diastereoisomers and the in silico potential as well as the biological activity.

Physiological and productive responses of multiparous lactating Holstein cows exposed to short-term cooling during severe summer conditions in an arid region of Mexico.

Heat stress generates a significant economic impact for the dairy industry in arid and semi-arid regions of the world, so that heat abatement is an important issue for dairy producers. The objective of this study was to evaluate effects of two short-term cooling periods on physiological and productive status of lactating Holstein cows during hot ambient temperatures. Thirty-nine multiparous cows were blocked by milk yield and assigned to one of three treatments including: control group (C), cows cooled before milking time (0500 and 1700 h daily, 1 h cooling); AM group, cows cooled at 1000 h and before milking (2 h cooling); and AM + PM group, cows cooled at 1100, 1500 and 2200 h, as well as before milking (4 h cooling). The cooling system was placed in the holding pen which the cows were moved through for cooling. Respiratory rate, and temperatures of thurl and right flank, were lower (P < 0.05) in cows from the AM + PM group than AM and C cows during the morning and afternoon. However, udder temperature was higher in the AM + PM group compared to AM and C groups during the afternoon, although lower than the AM group during the morning. Rectal temperature was similar in all groups. Thyroxin concentrations tended (P < 0.10) to be lower in AM + PM relative to the AM and C groups. The AM + PM group had higher (P < 0.05) milk production than C (18.70 vs. 17.43 kg, respectively), and AM + PM cows had a trend (P < 0.10) to increased milk energy output vs. the C and AM groups (13.75 vs. 13.18 and 13.15 Mcal, respectively). Protein and fat in milk, body condition score, glucose, cholesterol, triglycerides and triiodothyronine were similar among the groups. Four hours of cooling with spray and fans during severe summer temperatures only modestly improved milk yield of lactating Holstein cows.