A protocol for presynchronization of ovarian status with 2 injections of PGF2α given 14 d apart, with the last PGF2α injection given 12 or 14 d before Ovsynch increases pregnancy per artificial insemination (P/AI) in dairy cows. We determined the efficacy of reducing the interval from the last PGF2α injection (500 μg of cloprostenol) of presynchronization to initiation of Ovsynch on response to treatment and P/AI. Lactating dairy cows were assigned to an Ovsynch protocol, with the initial injection of GnRH given either 9 (PRE-9; n=135) or 12d (PRE-12; n=135) after the second PGF2α injection of presynchronization. The Ovsynch protocol consisted of 2 injections of 100 μg of GnRH given 9 d apart and 1 injection of PGF2α given 7 d after the initial GnRH injection, and cows were subjected to timed artificial insemination (TAI; 70±3.5 DIM) approximately 16 h after the second GnRH injection. Body condition score (1-5 scale) was recorded at TAI. Blood samples were taken for progesterone determination at the PGF2α injection of Ovsynch, at TAI, and at 11 d after TAI. Ultrasonographic examinations were done in all cows at the second PGF2α injection of presynchronization, initial GnRH injection, PGF2α injection of Ovsynch, at TAI, and 24 h after TAI for cyclicity status and ovarian responses to treatments, and at 32 and 60 d after TAI for confirmation of pregnancy. Overall, 29 cows (10.7%) were determined acyclic or cystic and excluded from the study. The percentage of cows responding to initial GnRH injection (62.2 vs. 61.5%) did not differ between PRE-9 and PRE-12 but more cows in the PRE-9 group failed to respond to PGF2α treatment of Ovsynch compared with PRE-12 (22.7 vs. 10.7%). Body condition score at TAI (2.9±0.02) and mean ovulatory follicle diameter (16.4±0.2 mm) were not different between treatments. Overall P/AI at 32 d was reduced in PRE-9 (33.6%) compared with PRE-12 (44.3%) but pregnancy losses (5.0 vs. 3.7%) did not differ between treatments. Primiparous cows in the PRE-12 group had higher mean progesterone concentration 11 d after TAI and greater P/AI 32 after TAI than primiparous cows in the PRE-9 group (6.4±0.5 vs. 4.6±0.5 ng/mL and 55.8 vs. 30.0%, respectively). In conclusion, reducing the interval from the last PGF2α injection of the presynchronization treatment to initiation of Ovsynch (from 12 to 9 d) did not affect ovulatory response to initial GnRH injection but reduced response to PGF2α injection of Ovsynch and P/AI at 32 and 60 d after TAI. The reduction in P/AI was particularly evident in primiparous cows of the PRE-9 group.

2012. Dairy cows continuously-housed in tie-stalls failed to manifest activity changes during estrus. Can. J. Anim. Sci. 92: 189Á196. While pedometers are effective for estrus detection in free-stall herds, their efficacy in tie-stalls is not established. The objectives were to determine if pedometers equipped with a behavior tag for monitoring lying activity (AfiMilk Pedometer Plus Tag system) can accurately record cow activity, and if they can facilitate estrus detection in dairy cows continuously housed in tie-stalls. Nineteen lactating Holstein cows were subjected to estrus induction with prostaglandin F 2a , and 18 pregnant cows served as controls. Activity was monitored for 10 d using pedometers and 24-h video recording. Pedometer and video records were compared for 6 d surrounding estrus; stepping (rc 00.85; PB0.01), lying time (rc 00.94; PB0.01), and lying bouts (rc 00.89; PB0.01) were highly correlated. Progesterone concentrations confirmed that 17 of the 19 cows responded to estrus induction; 16 of those 17 cows ovulated. Changes in mean daily activity did not differ (P0.05) between estrus-induced cows and controls, or in the estrus-induced cows in the 48 to 72 h preceding the day of ovulation. In conclusion, while the pedometers accurately recorded cow activity in lactating cows housed in tie-stalls, they could not facilitate estrus detection because cow activity did not significantly change during estrus.

Our objective was to evaluate the effects of dietary starch content, altered by partial substitution of dietary grain with wheat dried distillers grain with solubles (DDGS), on the interval from calving to first ovulation, concentrations of hormones and metabolites in plasma and follicular fluid, and granulosa cell gene expression in preovulatory follicles. Sixty lactating dairy cows were assigned to 1 of 2 diets from calving until 84d postpartum. Diets were formulated to contain either 17.3% rolled barley grain (29.2% starch) or 17.2% wheat DDGS (19.1% starch), with 43.0% barley silage and 21.6% rolled corn grain as the other major ingredients (dry matter basis). Transrectal ultrasonography was performed twice weekly to monitor ovarian dynamics from 7 ± 2d postpartum until ovulation or until 56d in milk, whichever occurred earlier. Plasma concentrations of insulin and insulin-like growth factor-1 (IGF-1) were determined in all 60 cows, and that of glucose, fatty acids, and urea in a subset of 24 cows, representing those in which the first ovulation occurred spontaneously within 5 wk postpartum. Estradiol (proestrus) and progesterone (12d postovulation) in plasma were also measured. Concentrations of insulin, IGF-1, glucose, fatty acids, and urea were determined in follicular fluid (wk 9), and the expression of LH receptor, estrogen receptor β, cytochrome P450 aromatase, and plasma type glutathione peroxidase genes measured in granulosa cells obtained from the preovulatory follicles at wk 9 postpartum in the subset of 24 cows. Diets did not alter the interval from calving to first ovulation (32.3 ± 2.5d), but a significantly lower proportion of cows on the DDGS diet (20%) ovulated multiple (≥ 2) follicles at the first ovulation than those on the barley grain diet (40%). The incidence of multiple ovulations tended to be lower at first insemination (10 vs. 21% for cows fed DDGS and barley grain diets, respectively). Mean plasma concentration of insulin was higher in cows fed the barley grain diet (2.5 vs 1.6 IU/mL), and a diet by time interaction was noted, with cows on the barley grain ration having higher insulin from wk 6 to 12 postpartum; however, mean plasma IGF-1 concentration did not differ between dietary groups. In the subsets, mean plasma concentrations of metabolites or estradiol and progesterone were not affected by diet, parity, or diet by parity interactions. Cows on the DDGS diet had lower concentrations of IGF-I (69 vs. 108 ng/mL) and higher fatty acids (222 vs. 149 mEq/L) in the follicular fluid obtained from preovulatory follicles. Diet, parity, and diet by parity interactions did not affect the concentrations of insulin, glucose, urea, estradiol, and progesterone in follicular fluid. Diets did not alter the expression profiles of LHr, estrogen receptor β, CYP19, and GPx3 genes in granulosa cells. In summary, diets did not affect the interval from calving to first ovulation or granulosa cell gene expression. However, reducing dietary starch content by a partial replacement of dietary grain with wh...

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