Effects of prepartum lipid supplementation on FSH superstimulation and transferable embryo recovery in multiparous beef cows

The objective of this experiment was to determine the effect of prepartum lipid supplementation on the number and quality of embryos recovered following ovarian super-ovulation in postpartum suckled beef cows. Mature cows (n = 40) were assigned to one of two treatments (lipid versus. no lipid) and supplemented for approximately 40 days prior to calving. Supplements provided to cows were isocaloric and isonitrogenous. The treatment group was fed 1.6 kg hd(-1) per day of whole soybeans (WSB; 19.8% ether extract, and 41.8% crude protein) and the control group received a supplement consisting of 1.8 kg hd(-1) day of a soybean meal and soy-hull combination (SBS; 2.15% EE and 36.81% CP). Cows were synchronized using a GnRH [Cystorelin((R)) 100 microg im]-GnRH-PGF(2alpha) [Lutalyse 25 mg im] protocol. Cows were administered two injections of GnRH seven days apart and PG seven days after the second GnRH injection. Twenty-eight cows (WSB, n = 15; SBS, n = 13) responded to estrus synchronization and were superstimulated. Super-ovulation was initiated on day 8-10 of the synchronized cycle by twice-daily injections of pFSH (Pluset) over four days in decreasing doses using a total of 608.4 IU per cow. Prostaglandin F(2alpha) was administered 96 and 108 h after super-stimulation was initiated with FSH. Days postpartum (WSB = 59 days; SBS = 57 days) at initiation of FSH treatments were similar (P > 0.10) for both treatments. Cows were monitored for estrus activity by the HeatWatch Estrus Detection System. Twenty-seven cows (WSB, n = 15; SBS, n = 12) exhibited estrus after FSH and inseminated at 0, 12, and 24 h after the onset of estrus with 1, 2, and 1 units of semen, respectively. Embryos were recovered and evaluated 7-8 days later. Only cows that responded to FSH and that were inseminated were used for statistical analysis. Data were analyzed using the General Linear Models Procedure of SAS. Body condition scores did not differ (P > 0.10) between treatments when cows were evaluated at the initiation of the experiment, two weeks prior to calving, and at initiation of superovulation with FSH. Estrous cyclicity prior to the initiation of estrus synchronization did not differ (P > 0.10) between treatments. There was no difference (P > 0.10) between treatments in recovery of total embryos (WSB, 14.7 +/- 3.5; SBS, 17.5 +/- 3.0), transferable embryos (WSB, 10.3 +/- 2.5; SBS, 13.6 +/- 2.6), degenerate embryos (WSB, 3.3 +/- 1.1; SBS, 1.6 +/- 1.7) or unfertilized ova (WSB, 1.1 +/- 0.5; SBS, 2.3 +/- 1.2). Cows that were supplemented with whole soybeans prior to parturition failed to produce an increased total number of ova or transferable embryos following super-ovulation.