Late-gestation ear-surface temperatures and subsequent postpartum health, activity, milk yield, and reproductive performance of dairy cows.

A retrospective study was conducted to determine if postpartum health, milk yield, and reproductive traits in addition to peripartum daily physical activities (resting, eating, active time, and rumination) differ in dairy cows having greater or lesser ear-surface temperatures during late gestation (Days 230-239) compared with contemporary herd mates within season. Herd records collected from Holstein heifers (n = 348) and dry cows (n = 503; second through seventh lactations) were fitted with SensOor ear tags to collect hourly ear-surface temperatures. Mean temperatures were calculated from 240 hourly measures during Days 230-239 of gestation and cows within season were grouped into two median temperature groups. On Days 230-239 of gestation during May through September (hotter months) cows with high (H, range of 33.67-38.89 °C, mean ± SEM = 32.9 ± 0.2 °C) or medium high (MH, 25.06-31.66 °C, 29.4 ± 0.2 °C) temperatures were grouped together (n = 209 per group). For comparable gestational days during October through April (colder months), cows with medium low (ML, 17.82-25.00 °C, 21.1 ± 0.2 °C) and low (L, -0.70 to 17.80 °C, 13.4 ± 0.2 °C) temperatures were grouped together (n = 216 per group). Prepartum traits including mean ear temperature, gestation length, days in milk at dry-off, days in close-up pen, previous 305-d milk yield, proportion of heifer calves born, and cow PTA for milk differed (P < 0.05) between seasons, but not between temperature groups within season, except predicted transmitting ability for milk was greater (P = 0.02) for ML than L cows. Postpartum treatment with antimicrobials occurred more (P = 0.02) often in H than MH cows, whereas more (P = 0.04) lameness and greater (P = 0.05) projected 305-d mature equivalent milk yield was observed in ML vs. L cows. No other health or reproductive traits were associated with temperature group, but many seasonal effects were observed across temperature groups. Less (P = 0.04) prepartum eating time during the last 10 d before calving was detected in L than in ML cows, less (P = 0.06) rumination time in ML than L cows, and more (P = 0.03) activity time was observed in H than MH cows. After calving, H cows were more (P = 0.03) active than MH cows and ML cows tended (P = 0.07) to be more active than L cows. In conclusion, late gestational ear-surface temperatures were associated with some postpartum health disorders and modifications in daily eating, ruminating, and active times during the transition period of gravid heifers and dry cows.

Transition cow metabolites and physical traits influence days to first postpartum ovulation in dairy cows.

Physical activities are associated with the health of transition dairy cows and pregnancy outcomes are positively related to early resumption of postpartum estrous cycles. The objective was to assess key metabolites and patterns of prepartum and postpartum physical activity as they relate to the onset of first postpartum ovulation in lactating dairy cows. Close-up dry Holstein cows (n = 82) and late gestation heifers (n = 78) were enrolled beginning 3 wk before expected calving date (Day 0). Cows were fit with Cow SensOor ear tags to assess transitional changes in eating, resting, rumination, high activity, and ear-surface temperatures. Rectal temperatures were assessed and blood samples were collected on Days 0, 3, 7, and 14 to measure concentrations of glucose, free fatty acids (FFA), ß-hydroxybutyrate (BHB), calcium, and haptoglobin. Body condition scores (BCS) and body weights (BW) were measured weekly, and blood samples were collected weekly from Day 21 ± 3 through 70 ± 3 to quantify changes in progesterone to detect luteal function after ovulation. Cows first ovulating before median Day 33 were classified as early (n = 76), whereas those first ovulating after Day 33 were classified as late (n = 84). Early ovulating cows first ovulated earlier (P < 0.001) than the late ovulation cows (24.3 ± 1.2 d [range: 16-32 d] vs. 48.8 ± 1.2 d [range: 33-74 d]), respectively. Mean days to first ovulation excluded seven cows that failed to ovulate before insemination. Compared with late ovulating cows, early ovulating cows had lesser (P < 0.05) concentrations of FFA, BHB, and haptoglobin on Days 0, 3, 7, and 14 in addition to having lesser (P < 0.05) rectal temperatures and ear-surface temperatures. Ear-surface temperatures began to decrease 4 d before parturition and remained less (P < 0.05) after calving than cows that subsequently ovulated late. Early ovulating cows tended (P = 0.07) to spend more time eating, and less (P = 0.02) time resting and being active during the first 3 wk after calving, and lost less (P = 0.03) BW and BCS during the first 9 wk compared with late ovulating cows. Although no differences were detected in yields of milk or energy-corrected milk during the first 9 wk after calving, early compared with late ovulating cows produced more (P < 0.01) milk protein. We concluded that metabolic measures during the first 2 wk after calving, and physical and behavioral traits are associated with the onset of postpartum ovarian activity.

Review: Perspective on high-performing dairy cows and herds.

Milk and dairy products provide highly sustainable concentrations of essential amino acids and other required nutrients for humans; however, amount of milk currently produced per dairy cow globally is inadequate to meet future needs. Higher performing dairy cows and herds produce more milk with less environmental impact per kg than lower performing cows and herds. In 2018, 15.4% of the world's dairy cows produced 45.4% of the world's dairy cow milk, reflecting the global contribution of high-performing cows and herds. In high-performing herds, genomic evaluations are utilized for multiple trait selection, welfare is monitored by remote sensing, rations are formulated at micronutrient levels, health care is focused on prevention and reproduction is managed with precision. Higher performing herds require more inputs and generate more waste products per cow, thus innovations in environmental management on such farms are essential for lowering environmental impacts. Our focus is to provide perspectives on technologies and practices that contribute most to sustainable production of milk from high-performing dairy cows and herds.

Resynchronizing the first eligible estrus in dairy cattle after a prior insemination and fertility of the prior insemination after gonadotropin-releasing hormone and progesterone treatments.

The hypothesis of this study tested whether application of designed treatments to synchronize estrus in nonpregnant previously inseminated lactating dairy cows increased the proportion of nonpregnant cows in estrus before early pregnancy diagnosis on Day 32 after the previous insemination (Day 0) and increase fertility of the pretreatment insemination. A progesterone insert (CIDR) and GnRH were applied to cows after insemination to resynchronize the returning estrus of cows that failed to conceive on Day 0. The combination of GnRH (Day 14) and a CIDR insert (d 17 through 24) in experiment 1 (n = 347 cows) did not increase (P = 0.13) the proportion of nonpregnant cows returning to estrus before pregnancy diagnosis, but increased (P < 0.01) the synchrony of their return by 24.4% points, and delayed (P < 0.01) that return by 2.3 ± 0.3 d compared with controls. Ovulation risk after GnRH treatment on Day 14 was only 10%. For cows that failed to return to estrus before Day 32, progesterone concentration on Days 14 and 17 were less than that in cows that returned to estrus by Day 32 and in pregnant cows. Cows that returned to estrus had larger follicles and fewer numbers of CL on Day 21 than pregnant cows and cows that failed to return to estrus, but concentrations of pregnancy-associated glycoproteins on Day 28 indicated that cows failing to return to estrus were likely pregnant but suffered embryo death. In experiment 2 (n = 881), use of GnRH alone (Day 7), a CIDR insert alone (Days 14 through 21), or in combination, failed to increase the proportion of nonpregnant cows in estrus before pregnancy diagnosis on Day 32 compared with controls. Cows receiving the CIDR insert had increased (P < 0.01) synchrony of estrus by 24-34% points compared with cows that did not receive a CIDR insert. More cows receiving GnRH had 2 or more CL on Days 14 and 21 compared with controls. Ovulation risk after GnRH on Day 7 was greater than 66%. In both experiments combined, treatments with GnRH or GnRH + CIDR insert increased (P = 0.015) pretreatment pregnancy per AI by 7.1% points, but did not affect pregnancy loss. Although administering GnRH with or without a CIDR insert synchronized returns to estrus, treatments failed to increase the proportion of nonpregnant cows reinseminated before pregnancy diagnosis, but increased pretreatment pregnancy risk.

Luteolysis, progesterone, and pregnancy per insemination after modifying the standard 7-day Ovsynch program in Holstein-Friesian and Holstein cows.

Two experiments were conducted with Holstein-Friesian cows in the Republic of North Macedonia and with Holstein cows in Kansas. We hypothesized that 1 dose of PGF2α administered on d 8 (Ov-8×1) instead of d 7 (Ov-7×1) in an Ovsynch program [GnRH-1 (d 0)-7 d-PGF2α-56 h-GnRH-2-16 h-timed artificial insemination (AI)] would increase the proportion of cows with complete luteolysis compared with controls receiving a single dose on d 7. Cows were treated with Ov-7×1 or with Ov-8×1 in experiment 1 (n = 347), using only a single dose of PGF2α. In experiment 2 (n = 452), a third treatment was added (Ov-7×2), in which a second dose of PGF2α was administered on d 8. Progesterone was measured in blood samples collected before the first or only PGF2α administration and 72 h later before insemination. Complete luteolysis was defined as having occurred when progesterone was ≥1 ng/mL before PGF2α and ≤0.3 ng/mL 72 h later (time of AI). Follicles and luteal structures were mapped before GnRH-1 and PGF2α administrations. The results of experiment 1 demonstrated a greater percentage of multiparous cows in OV-8×1 having complete luteal regression compared with multiparous Ov-7×1 cows, whereas treatments were equally effective in primiparous cows, as reflected in the concentrations of progesterone before AI. Furthermore, pregnancy per AI did not differ between treatments. Results in experiment 2 revealed that 99.3% of cows in the Ov-7×2 treatment receiving the second dose of PGF2α had complete luteolysis, regardless of parity, compared with significantly fewer cows in the Ov-7×1 and Ov-8×1 treatments (91.2 and 90.6%, respectively). Neither concentrations of progesterone, which averaged <0.4 ng/mL at AI, nor pregnancy per AI differed among the 3 treatments. In both experiments, when status of luteal function before PGF2α treatment was examined [cows with no corpus luteum (CL) before GnRH-1 but which had formed a new CL in response to ovulation after GnRH-1; cows with an older CL (the same CL that was detected before GnRH-1); or cows with both a new and an older CL], treatments did not differ in causing complete luteolysis. Furthermore, complete luteolysis in experiment 2 did not differ regardless of whether cows had 1, 2, or 3 or more CL before PGF2α administration. Pregnancy per AI did not differ among treatments, indicating that any of the 3 treatments might produce similar pregnancy outcomes with the flexibility of applying either of the 7- or the 8-d treatments.

First postpartum ovulation, metabolites and hormones in follicular fluid and blood in transition dairy cows supplemented with a Saccharomyces cerevisiae fermentation product.

We hypothesized that feeding a Saccharomyces cerevisiae fermentation product (SCFP) from -4 through +7 wk (calving = Day 0) facilitates early first postpartum ovulation and alters blood and follicular fluid concentrations of glucose, beta-hydroxybutyrate (BHB), free fatty acids (FFA), and steroid hormones favorable to subsequent fertility. Holstein cows were fed individually a SCFP product (n = 24) or served as controls (n = 23). Blood samples were collected at wk -4 and -2 from expected calving and at 1, 2, 5, and 7 wk postpartum to determine plasma concentrations of FFA and BHB. Early spontaneous ovulation (progesterone > 1 ng/mL or corpus luteum presence by postpartum median Day 33) or late ovulation was determined. Plasma FFA in weekly samples was not affected by SCFP supplementation, but FFA was greater (P < 0.01; week by ovulation status) in late compared with early ovulating cows during and after postpartum wk 2. Plasma BHB in weekly samples was greater (P = 0.03) in SCFP than control cows and tended (P = 0.06) to be greater in late than early ovulating cows. Cows were exposed to ovulation synchronization (GnRH, PGF2α, and GnRH on Days 33, 40, and 43 ± 3, respectively). Transvaginal dominant follicle aspiration was conducted at Day 50, 7 d after GnRH on Day 43. Metabolites (FFA, BHB, and glucose) and steroid hormones (progesterone, androstenedione, and estradiol) measured in follicular fluid and blood samples collected at aspiration revealed that androstenedione in serum was numerically less (P = 0.11) in SCFP-treated compared with control cows, whereas androstenedione in serum was less (P < 0.05) in late than early ovulating cows. Concentrations of BHB (r = 0.75) and glucose (r = 0.52) in follicular fluid were positively correlated (P < 0.01) with those in blood. Body weight at calving and Day 42 was less (P ≤ 0.05), and energy balance through Days 28 and 42 was more positive (P < 0.05) in early than late ovulating cows and in SCFP-supplemented compared with control cows (P < 0.05). Dry matter intake, daily milk yield, and yields of fat, protein, lactose, and total solids were less (P < 0.01) in early compared with late ovulating cows, whereas milk fat percentage was increased (P < 0.01) by SCFP supplementation. We conclude that elevated postpartum BHB and FFA in plasma, greater negative energy balance, and greater milk yield and components were associated with later postpartum ovulation, but metabolites and steroid hormones in blood and follicular fluid were unaffected by SCFP treatment or ovulation status except for androstenedione.

Physiologic responses to feeding rumen-protected glucose to lactating dairy cows.

It was hypothesized that rumen-protected glucose (RPG) in diets of dairy cows increases concentrations of insulin resulting in greater blood progesterone concentrations because elevated insulin decreases activity of liver enzymes inactivating steroid hormones. Timing of ovulation was synchronized among 64 postpartum Holstein cows using GnRH and PGF2α (Day 0 = ovulation). Cows were milked thrice daily and assigned randomly a basal diet supplemented with 0, 1, 2, or 4 kg of an RPG product in place of corn grain, top-dressed in the diet beginning on Day -3. Blood was collected pre- and post-prandial on Days 0, 2, and 4 to determine plasma glucose and insulin concentrations and daily from Days 2 through 12. Intake of crude protein and energy-soluble carbohydrates increased linearly with dose, whereas starch intake decreased linearly with dose. Neither daily milk yield nor dry matter intake (DMI), energy-corrected milk (ECM), somatic cell count, or percentages of milk fat, protein and lactose on Day 8 differed among dietary treatments. Neither pre- nor post-prandial changes in plasma glucose differed among treatments. In contrast, post-prandial glucose decreased from Days 0 through 4. A change in plasma insulin (post-prandial minus pre-prandial) was detected. Milk urea nitrogen increased linearly with RPG dose. Concentrations of progesterone were unaffected by RPG dose. It is concluded that insulin response to RPG was decreased relative to the control and RPG supplementation linearly increased crude protein intake and milk urea nitrogen with increasing dose, but did not affect concentrations of progesterone, milk yield, or dry matter intake.

A shortened resynchronization treatment for dairy cows after a nonpregnancy diagnosis.

We hypothesized that a shortened version of a modified Ovsynch program (OVS: GnRH-1 - 7 d - PGF2α-1 - 24 h - PGF2α-2 - 32 h - GnRH-2 - 16 h - AI) that excluded GnRH-1 to resynchronize ovulation in cows bearing a corpus luteum (CL) after a non-pregnancy diagnosis (NPD) or including progesterone supplementation with the OVS treatment for cows without a CL would produce shorter inter-insemination intervals and pregnancy per AI (P/AI) not different from that of cows treated with the OVS treatment. Of the 1697 lactating Holstein cows enrolled in this experiment, complete data were available for only 1584 cows because the remainder was not treated, inseminated per treatment design, left the herd before pregnancy diagnosis, or some other outcome was missing. Cows were enrolled in the study and assigned to either of three treatments at NPD (32 ±â€¯3 d after AI [Day 0]). Cows with a detected CL were assigned randomly to: (1) a modified Ovsynch (OVS; GnRH-1 - 7 d - PGF2α-1 - 24 h - PGF2α-2 - 32 h - GnRH-2 - 16 h - AI) or (2) Short Synch (SS; PGF2α-1 - 24 h - PGF2α-2 - 32 h - GnRH-2 - 16 h - AI). Cows with no CL were assigned to OVS plus a progesterone insert (CIDR). Blood was collected at NPD to measure progesterone concentration and determine accuracy of treatment assignment (progesterone ≥ 1 ng/mL for a functional CL). Overall progesterone concentration at NPD was less in OVS + CIDR cows (1.5 ± 0.3 ng/mL) than in OVS (5.2 ± 0.2 ng/mL) or SS cows (3.7 ± 0.3 ng/mL). No differences in luteolytic risk (progesterone < 0.5 ng/mL at 72 h after PGF2α-1) were detected after PGF2α (>96.7%) and ovulation risk after GnRH-2 was 93.8, 91.7, and 86.2% for SS, OVS, and OVS + CIDR, respectively. Mean and median inter-insemination interval were less in SS (mean = 34.3 ± 0.05 d [median = 35 d] than OVS cows (40.2 ± 0.05 d [42 d]), but that in OVS cows did not differ from OVS + CIDR cows (41.4 ± 0.05 d [42 d]). Technicians were more accurate in visually detecting a functional CL than a non-functional CL (81.2 vs. 61.1%). Sensitivity of detecting a functional CL by technicians averaged 91.2%, but specificity was 39.8%. Pregnancy per AI at 32 ± 3 d after AI was less for SS (16.5% [n = 115]) than OVS (29.3% [n = 133] when a functional CL was inaccurately detected, but did not differ when a functional CL was detected accurately (27.6% [n = 561] vs 30.3% [508]). Pregnancy per AI did not differ between OVS and OVS + CIDR cows regardless of CL status. Short synch is an alternative to the entire modified Ovsynch program to produce similar P/AI when the CL status was detected accurately, and regardless of functional CL status, SS reduced inter-insemination intervals by 7 d.

Spatial relationships of ovarian follicles and luteal structures in dairy cows subjected to ovulation synchronization: Progesterone and risks for luteolysis, ovulation, and pregnancy.

Objectives were to determine relative ovary location of follicles, GnRH-induced corpora lutea (CL), and older CL present in ovaries as part of ovulation synchronization and their associations with progesterone concentration and risk for luteolysis, ovulation, and pregnancy. Cows were exposed to a timed artificial insemination (AI) program [GnRH-1-7 d-PGF2α (1 dose or 2 doses 24 h apart)-56 h after first or only dose of PGF2α-GnRH-2-16 h-timed AI at 72 ± 3 d in milk]. Blood was collected to assess progesterone when ovarian structures were mapped in 694 cows before GnRH-1 and before and 48 h after PGF2α and, in a subset of cows, size of CL (n = 599) and progesterone (n = 380) at 6 d after AI. Dominant follicles and CL in single-ovulating cows were detected more often in right than left ovaries (follicles before GnRH-1: 60.6% right and GnRH-2: 61.2% right; and CL before GnRH-1: 58.6% right and GnRH-2: 66.4% right). Dominant follicles in single-ovulating cows before GnRH-1 tended to be ipsilateral to the CL more often than contralateral (54.8 vs. 45.2%) with co-dominant follicles identified in both ovaries (19.3%). In response to GnRH-1 or GnRH-2, more left-ovary follicles ovulated contralateral to CL (left to right, 54.7%; right to left, 34.7%) than right-ovary follicles, but fewer left-ovary follicles ovulated ipsilateral to CL (left to left: 45.3%) than right-ovary follicles ovulated ipsilateral (right to right: 65.3%). Preovulatory follicles in single-ovulating cows before PGF2α tended to be detected more often ipsilateral than contralateral to CL induced by GnRH-1 (younger CL; 56.5 vs. 43.6%), but were of equal frequency ipsilateral or contralateral to older CL present before GnRH-1. Luteolytic risk was less in cows bearing co-dominant follicles in both ovaries compared with those in either right or left ovaries. Luteolytic risk in single-ovulating cows did not differ between ovaries. Luteolytic risk was greater for cows bearing older CL (86.5%) than for cows bearing younger GnRH-1-induced CL (65.3%) or both (79.6%). Pregnancy risk at 60 d after AI was or tended to be greater in cows having both CL types compared with either younger or older CL, respectively, partly because of greater embryonic loss in the latter 2 cases. More female calves tended to be carried in right horns when conception occurred after first service, whereas the opposite greater female frequency occurred in left horns after repeat services. Right-ovary dominance is evident before and after GnRH treatment.

Presynchronization strategy using prostaglandin F2α, gonadotropin-releasing hormone, and detection of estrus to improve fertility in a resynchronization program for dairy cows.

Objectives of experiment 1 were to evaluate pregnancy outcomes and reinsemination patterns of cows whose estrous cycles or ovulation were presynchronized with prostaglandin (PGF2α) or PGF2α and gonadotropin-releasing hormone (GnRH) after non-pregnancy diagnosis in programs focusing on inseminating cows based on tail paint removal. Objectives of experiment 2 were to evaluate pregnancy outcomes and reinsemination patterns of cows with or without a corpus luteum (CL) present at non-pregnancy diagnosis in a program utilizing PGF2α and GnRH to presynchronize estrous cycles before resynchronization. Lactating Holstein cows from three herds were enrolled in the experiments at non-pregnancy diagnosis (d 0). Estrus was determined daily based on tail paint removal. In experiment 1, cows were assigned randomly to two treatments: (1) PGF2α on d 0 (n = 967; P7); and 2) PGF2α on d 0 and GnRH on d 7 (n = 962; P7G7). Cows not reinseminated based on tail paint removal were submitted to the timed-AI Cosynch-72 protocol 7 d after presynchronization treatments. Pregnancy per AI (P/AI) was greater (P = 0.01) for P7G7 cows than P7 cows. Cows inseminated based on tail paint removal had increased (P < 0.01) P/AI than cows submitted to the timed AI protocol. In addition, an interaction was detected (P = 0.03) between method of insemination and presynchronization treatment such that cows submitted to timed AI in the P7G7 treatment had greater P/AI than P7 cows. Nonetheless, P7 cows were inseminated at a faster rate (P < 0.01) than P7G7 cows. In experiment 2, presence of a CL was determined by transrectal ultrasonography at initiation of the P7G7 protocol (n = 1479). In a random subset of cows (n = 210), blood samples were collected immediately after ultrasound examination to determine progesterone concentration in order to evaluate accuracy of detection of a CL by ultrasonography. Accuracy of detection of a CL was 80%. Hazard to insemination and P/AI did not differ among cows regardless of CL status. In conclusion, herds relying mostly on detected estrus to reinseminate cows may achieve greater pregnancy outcomes if presynchronizing with PGF2α and GnRH instead of only PGF2α, albeit at a slower insemination rate. In addition, pregnancy outcomes and reinsemination patterns were similar for cows bearing or not bearing a CL when utilizing the P7G7 protocol, indicating a limited benefit of evaluating ovarian luteal structures by ultrasonography.

Dose frequency of prostaglandin F2α administration to dairy cows exposed to presynchronization and either 5- or 7-day Ovsynch program durations: Ovulatory and luteolytic risks.

We hypothesized (1) that neither duration of the Ovsynch program nor dose frequency of PGF2α would change the proportion of cows with complete luteolysis (progesterone <0.4 ng/mL 72 h after PGF2α) and (2) that the additional GnRH treatment administered as part of a presynchronization program would not alter the proportion of anovulatory cows starting the timed artificial insemination (AI) program compared with an alternative shorter presynch program including only 1 GnRH treatment. Lactating Holstein cows (n = 406) were milked 3 times daily and enrolled in a 2 × 2 × 2 factorial experiment consisting of 8 treatments before the first postpartum AI. Treatments were used to test ovulatory, luteal, and luteolytic outcomes to 3 main effects: (1) 2 GnRH-PGF2α presynchronization programs (PG-3-G vs. Double Ovsynch), (2) 2 Ovsynch program durations [5 d: GnRH (GnRH-1)-5 d-PGF2α-24 h-PGF2α-32 h-GnRH (GnRH-2)-16 h-timed AI; 7 d: GnRH-1-7 d-PGF2α-56 h-GnRH-2-16 h-timed AI], and (3) 2 PGF2α dose frequency treatments (2 × 25 mg) 24 h apart versus 1 dose (1 × 50 mg) of PGF2α administered 72 h before timed AI. The presynchronization treatments of PG-3-G and Double Ovsynch had no effect on the proportion of cows with luteal function at the onset of the Ovsynch treatments (87.9 vs. 86.2%). Although ovulatory responses were similar after GnRH-1 (>60%), Double Ovsynch cows tended to have greater ovulatory responses than PG-3-G after GnRH-2 (95.3 vs. 90.6%). The 2 × 25-mg doses of PGF2α and the 1 × 50-mg dose induced luteolysis in both Ovsynch treatment durations, but the 1 × 50-mg dose was less effective in the 5-d program. More pregnancy per AI (P/AI; 49.2%) tended to occur in the PG-3-G cows in the 7-d program compared with the other treatment combinations (range: 32.4-37.4%; Ovsynch × presynch interaction). In addition, an Ovsynch × PGF2α dose frequency interaction resulted in cows receiving the 1 × 50-mg dose in the 7-d program having the greatest P/AI (46.1%) and cows receiving the 1 × 50-mg dose in the 5-d program having the least P/AI (30.6%). We conclude that complete luteolysis was less effective in the 5-d program when the 1 × 50-mg dose was applied, but both PGF2α dose frequencies (1 × 50 mg and 2 × 25 mg 24 h apart) effectively induced complete luteolysis in the 7-d program. Treatments producing complete luteolysis tended to be related to subsequent pregnancy outcomes.

Invited review: Learning from the future-A vision for dairy farms and cows in 2067.

The world's population will reach 10.4 billion in 2067, with 81% residing in Africa or Asia. Arable land available for food production will decrease to 0.15 ha per person. Temperature will increase in tropical and temperate zones, especially in the Northern Hemisphere, and this will push growing seasons and dairy farming away from arid areas and into more northern latitudes. Dairy consumption will increase because it provides essential nutrients more efficiently than many other agricultural systems. Dairy farming will become modernized in developing countries and milk production per cow will increase, doubling in countries with advanced dairying systems. Profitability of dairy farms will be the key to their sustainability. Genetic improvements will include emphasis on the coding genome and associated noncoding epigenome of cattle, and on microbiomes of dairy cattle and farmsteads. Farm sizes will increase and there will be greater lateral integration of housing and management of dairy cattle of different ages and production stages. Integrated sensors, robotics, and automation will replace much of the manual labor on farms. Managing the epigenome and microbiome will become part of routine herd management. Innovations in dairy facilities will improve the health of cows and permit expression of natural behaviors. Herds will be viewed as superorganisms, and studies of herds as observational units will lead to improvements in productivity, health, and well-being of dairy cattle, and improve the agroecology and sustainability of dairy farms. Dairy farmers in 2067 will meet the world's needs for essential nutrients by adopting technologies and practices that provide improved cow health and longevity, profitable dairy farms, and sustainable agriculture.

Serum and plasma metabolites associated with postpartum ovulation and pregnancy risks in suckled beef cows subjected to artificial insemination.

Two experiments were conducted to determine relationships of blood metabolite concentrations, BW, BCS, and rump fat depth with postpartum ovulation and pregnancy risks, as well as their utility in predicting those outcomes in suckled beef cows. In experiment 1, plasma glucose collected 10 and 3 d before AI of suckled beef cows at seven locations did not differ between cows that had resumed estrous cycles (ovulated) before AI compared with anovulatory cows, whereas plasma glucose 3 d before AI was greater (P < 0.01) in cows that became pregnant compared with nonpregnant cows. Serum beta-hydroxybutyrate (BHB) tended (P = 0.09) to be less in ovulatory cows compared with anovulatory cows 10 d before AI, but was unrelated to pregnancy status. Receiver-operator derived true-positive (sensitivity) and false-positive (1-specificity) risks were determined for plasma glucose and serum BHB as predictors for postpartum ovulation and pregnancy status. Serum BHB 3 d before AI produced true-positive and false-positive risks of 82% and 37%, respectively, when predicting ovulatory status before AI. Serum BHB 10 d before AI produced a true-positive and false-positive risks of 92% and 25%, respectively, when predicting pregnancy status. In experiment 2, blood was collected weekly for 12 wk from multiparous suckled beef cows to assess blood metabolite concentrations in addition to concurrent weekly assessments of BW, BCS, and rump fat. When blood metabolites and physical measures were normalized to parturition reflecting changes occurring during the first 6 wk after calving, we observed reduced (P < 0.05) concentrations of serum BHB and NEFA, and greater (P < 0.05) rump fat and BCS in cows that ovulated before first AI, whereas reduced (P < 0.05) plasma glucose was characteristic of cows that became pregnant. When blood metabolites and physical measures were normalized to the onset of the AI program reflecting changes during 6 wk before AI, ovulatory cows had increased (P < 0.05) BCS and lower (P < 0.05) NEFA from 3 to 6 wk before the onset of the AI program compared with anovulatory cows. With all predictor variables in regression models, some multiple correlation coefficients (R2) exceeded 50% when predicting postpartum ovulatory status, but those for predicting pregnancy risk were less than 25%. Although measures of BCS and BHB during 6 wk after calving were related to postpartum ovulation risk, rump fat, glucose, BCS, and NEFA were associated with cows that were ovulatory and pregnant.

Response of lactating dairy cows with or without purulent vaginal discharge to gonadotropin-releasing hormone and prostaglandin F2α.

Purulent vaginal discharge (PVD) is a common uterine disease in dairy cattle that has negative effects on reproductive performance. Reproductive management programs that synchronize ovulation use gonadotropin-releasing hormone (GnRH) to induce ovulation and prostaglandin F2α (PGF2α) to induce luteolysis. The objectives of this study were to evaluate ovarian response to treatment with GnRH and the odds of bearing a corpus luteum or being inseminated in dairy cows with or without PVD. Another objective was to determine the hazard of insemination after administration of PGF2α in dairy cows with or without PVD. Primiparous (n = 291) and multiparous (n = 402) cows were evaluated for PVD using a Metricheck device at 46 ± 3 and 35 ± 3 days in milk (DIM) (study day 0), respectively. On study day 14, primiparous (n = 107) and multiparous (n = 197) cows were treated with GnRH and subsequent ovulation was recorded. Primiparous (n = 178) and multiparous (n = 368) cows not inseminated by study day 21 were administered PGF2α and response to PGF2α treatment was determined by detection of estrus. Furthermore, cows were categorized by the presence of a CL or being inseminated by study days 14, 21, and 35. Overall prevalence of PVD was 28.5% and 13.4% for primiparous and multiparous cows, respectively. Projected 305-d milk yield was less (P < 0.01) in PVD+ multiparous cows compared with PVD- multiparous cows, however, no (P = 0.26) difference was detected between primiparous PVD+ and PVD- cows. Ovulatory response to GnRH treatment was 51.8% and 47.8% for primiparous and multiparous cows, respectively. Primiparous PVD- cows tended (P = 0.06) to be less likely to ovulate to GnRH than primiparous PVD+ cows, whereas multiparous PVD+ cows were less (P = 0.04) likely to ovulate to GnRH than PVD- multiparous cows. The odds of bearing a corpus luteum or being inseminated by study days 14, 21, or 35 was not associated with PVD in primiparous cows. In contrast, the odds of bearing a corpus luteum or being inseminated by study days 14 and 21 was (P ≤ 0.03) associated with PVD in multiparous cows, but not (P = 0.11) on study day 35. Hazard of insemination after PGF2α was not (P ≥ 0.38) associated with PVD in primiparous or multiparous cows. Purulent vaginal discharge is associated with response to treatment with GnRH in dairy cattle. Purulent vaginal discharge might negatively affect reproductive management programs that use GnRH to induce ovulation.

Additional small dose of prostaglandin F2α at timed artificial insemination failed to improve pregnancy risk of lactating dairy cows.

Two experiments were performed to test the hypothesis that administering PGF2α concurrent with timed artificial insemination (AI) in lactating dairy cows would enhance pregnancy per AI (P/AI). In experiment 1, lactating Holstein cows (n = 289) in one herd were enrolled after a non-pregnancy diagnosis (30-36 d after AI) to synchronize subsequent ovulation before AI. Cows were assigned randomly to receive (im) 10 mg of PGF2α concurrent with timed AI (Day 0; treatment) or no injection (control). Blood samples were collected on Days -3, 0, and 13 to determine serum concentrations of progesterone. Ovaries were scanned via transrectal ultrasonography to determine follicle diameters (Day -3), subsequent ovulation risk (Day 13), and total volume of luteal tissue (Day 13). Diagnosis of pregnancy occurred on Days 32 and 80 after AI. Ovulation risk post-AI exceeded 90% and did not differ between treatments. In addition, PGF2α treatment only numerically increased progesterone (5.7 ±â€¯0.3 vs. 6.2 ±â€¯0.3 ng/mL) or luteal tissue volume (8.9 ±â€¯0.4 vs. 9.8 ±â€¯0.5 ng/mL) on Day 13 by 8.8% (P = .206) or 10.1% (P = .134) in control and treated cows, respectively. Pregnancy per AI at Days 32 (P = .50) and 80 (P = .33) did not differ between treatments. Cows with progesterone >0.5 ng/mL at timed AI had reduced (P < .001) ovulation risk but risk was unaffected by treatment. In experiment 2, lactating dairy cows (n = 1828) in two commercial dairy herds were enrolled at time of insemination (Day 0), and assigned randomly to treatment or control as described in experiment 1. Initial (Days 32-35) and confirmed (Days 63-68) pregnancy diagnosis revealed no differences in P/AI or pregnancy loss. Pregnancy diagnosis on Days 32-35 produced percentage increases in P/AI for primiparous compared with multiparous cows (20.8%; P = .002), for first-service compared with repeat-service cows (26%; P = .001), and cows in one herd compared with the second herd (36%; P < .001). Pregnancy loss was greater (P = .001) for cows inseminated at first (10.0%) vs. later services (5.3%) but was unaffected by treatment. Cows treated with PGF2α in one herd produced more twins than control cows (11.7 vs. 3.2%), whereas no treatment difference was detected in the second herd (5.6 vs. 5.6%), respectively. We conclude that im treatment of lactating dairy cows with 10 mg of PGF2α concurrent with timed AI did not improve P/AI or embryo survival, but increased twinning in one herd.

A 100-Year Review: Practical female reproductive management.

Basic knowledge of mechanisms controlling reproductive processes in mammals was limited in the early 20th century. Discoveries of physiologic processes and mechanisms made early in the last century laid the foundation to develop technologies and programs used today to manage and control reproduction in dairy cattle. Beyond advances made in understanding of gonadotropic support and control of ovarian and uterine functions in basic reproductive biology, advancements made in artificial insemination (AI) and genetics facilitated rapid genetic progress of economically important traits in dairy cattle. Technologies associated with management have each contributed to the evolution of reproductive management, including (1) hormones to induce estrus and ovulation to facilitate AI programs; (2) pregnancy diagnosis via ultrasonography or by measuring conceptus-derived pregnancy-associated glycoproteins; (3) estrus-detection aids first devised for monitoring only physical activity but that now also quantitate feeding, resting, and rumination times, and ear temperature; (4) sex-sorted semen; (5) computers and computerized record software packages; (6) handheld devices for tracking cow location and retrieving cow records; and (7) genomics for increasing genetic progress of reproductive and other economically important traits. Because of genetic progress in milk yield and component traits, the dairy population in the United States has been stable since the mid 1990s, with approximately 9 to 9.5 million cows. Therefore, many of these technologies and changes in management have been developed in the face of increasing herd size (4-fold since 1990), and changes from pastoral or dry-lot dairies to increased housing of cows in confinement buildings with freestalls and feed-line lockups. Management of groups of "like" cows has become equally important as management of the one. Management teams, including owner-managers, herdsmen, AI representatives, milkers, and numerous consultants dealing with health, feeding, and facilities, became essential to develop working protocols, monitor training and day-to-day chores, and evaluate current trends and revenues. Good management teams inspect and follow through with what is routinely expected of workers. As herd size will undoubtedly increase in the future, practical reproductive management must evolve to adapt to the new technologies that may find more herds being milked robotically and applying technologies not yet conceived or introduced.

Fertility of lactating dairy cows treated with gonadotropin-releasing hormone at AI, 5 days after AI, or both, during summer heat stress.

Objectives of this experiment were to evaluate pregnancy per AI (P/AI) and progesterone (P4) concentrations after AI of lactating dairy cows under heat stress conditions treated with 100 µg gonadotropin-releasing hormone (GnRH) at AI, 5 d after AI, or both. Lactating Holstein cows from two herds were enrolled in the study during summer. Cows detected in estrus based on tail paint removal were allocated to four treatments: (1) control (CON = 722); (2) GnRH treatment at AI (G0 = 739); (3) GnRH treatment 5 d post-AI (G5 = 697); or (4) GnRH treatment at AI and 5 d post-AI (G0+G5 = 697). Blood samples were collected from a subgroup of cows at AI (study d 0), study d 5 and 12 to determine P4 concentrations. Pregnancy diagnosis was conducted at study d 36 and 94. Temperature and relative humidity were collected from a meteorological station nearest the herds and temperature-humidity index (THI) was calculated. Average THI during study enrollment was 83.8 ± 0.1 and THI at study d 0 tended (P = 0.09) to be associated with P/AI at study d 36, but it was not (P = 0.33) associated with P/AI at study d 94. Treatment with GnRH at AI, 5 d after AI, or both, did not affect (P ≥ 0.64) P/AI at study d 36 or 94. An interaction, however, was detected (P = 0.06) between treatment and lactation number. Such an interaction was observed because, among ≥ third-lactation cows, P/AI was greater for G0+G5 (28.6%) and G5 (25.3%) than CON cows (17.3%) at study d 36. Pregnancy per AI of ≥ third-lactation G0 cows did not (P ≥ 0.11) differ from CON, G5, and G0+G5 cows. No differences in P/AI were detected among treatments in first- and second-lactation cows. Overall, treatments with GnRH at AI, 5 d after AI, or both were not (P = 0.94) associated with P4 concentrations on study d 0, 5 or 12. Among cows diagnosed pregnant at study d 36, progesterone concentration on d 5 was not affected (P ≥ 0.24) by treatments with GnRH at AI, 5 d after AI, or both, but progesterone concentration on d 12 was greater for cows treated with GnRH at AI and 5 d after AI compared with G0 cows. Lactating dairy cows in their third or greater lactation exposed to heat stress conditions with compromised fertility may have increased P/AI after treatment with GnRH 5 d after AI or the combined treatment of GnRH at AI and 5 d after AI because of reduced early embryonic loss.

Increasing estrus expression in the lactating dairy cow.

Using an activity monitoring system (AMS) equipped with an accelerometer, 2 experiments were conducted to test the hypotheses that (1) enhancing progesterone before inducing luteolysis or (2) exposing cows to estradiol cypionate (ECP) or testosterone propionate (TP) after luteolysis would increase occurrence and intensity of estrus. Our goal was to determine if more cows could be detected in estrus by an AMS compared with other estrus-detection aids. In experiment 1, cows (n=154) were fitted with both an AMS collar and a pressure-sensitive, rump-mounted device (HeatWatch; HW) and assigned to 3 treatments: (1) no CL + progesterone insert (CIDR) for 5d, (2) CL only, or (3) CL + 2 CIDR inserts for 5d to achieve a range in concentrations of progesterone. Prostaglandin F2α was administered to all cows upon CIDR insert removal or its equivalent. Progesterone concentration up to 72h posttreatment was greatest in CL + 2 CIDR, followed by CL only, and no CL + CIDR cows. Estrus occurred 14 to 28h earlier in no CL + CIDR compared with CL-bearing cows. Estrus intensity was greater for CL + 2 CIDR than for CL-only cows. The AMS and HW detected 70 and 59% of cows defined to be in estrus, respectively. In experiment 2, cows (n=203) were equipped with both an AMS and a friction-activated, rump-mounted patch (Estrotect patch) and assigned to receive 1mg of ECP, 2mg of TP, or control 24h after PGF2α. Concentrations of estradiol 24 and 48h after treatment were greater in ECP cows compared with controls. Estrus expression detected by AMS or patches in cows defined to be in estrus tended to be greater or was greater for ECP compared with controls, respectively. Compared with controls and in response to TP or ECP, estrus occurred 8 to 18h earlier and was of greater intensity for ECP cows, respectively. The AMS and patches determined 73 and 76% of cows defined to be in estrus, respectively. Of cows exposed to the AMS, HW, or patches, 70, 61, and 75%, respectively, were detected in estrus and more than 93% of these subsequently ovulated. In contrast, of the residual cows not detected in estrus, 62 to 77% ovulated in the absence of detected estrus. Only ECP was successful in inducing more expression and intensity of estrus, and proportions of cows detected in estrus exceeded 80%. Given the large proportion of cows equipped with AMS collars ovulating in the absence of estrus, further research is warranted to determine if more pregnancies can be achieved by inseminating those cows not detected in estrus at an appropriate time when PGF2α is administered to induce luteolysis.

Two split-time artificial insemination programs in suckled beef cows.

Our objective was to determine which of 2 split-time AI programs applied to suckled beef cows would result in greater pregnancy risk. Suckled beef cows (n = 1,062) at 12 locations in 4 states (CO, KS, MY, and WA) were enrolled. Cows were treated on d -7 with a progesterone insert concurrent with 100 µg GnRH and on d 0 with 25 mg PGF plus removal of the insert. Estrus-detection patches were affixed to cows at insert removal. The study was designed as a completely randomized experiment of 2 treatment combinations. Within location and balanced for parity (primiparous vs. multiparous), cows were assigned randomly to 2 treatment times (55 vs. 65 h after CIDR insert removal) at which time estrus-detection patches were assessed. Estrus was defined to have occurred when an estrus-detection patch was > 50% colored (activated). Cows determined to be in estrus were inseminated at either 55 or 65 h, whereas the residual nonestrous cows in both treatment times received GnRH at 55 or 65 h but were inseminated 20 h later at 75 or 85 h, respectively. Pregnancy outcomes were determined at 36 d after AI and at the end of the breeding season. Thus, pregnancy outcomes of interest were compared between the 55 + 75-h treatment combination and that of the 65+85-h combination. Expression of estrus was greater ( = 0.001) by 65 h after PGF than by 55 h (62.0% vs. 41.9%), respectively, and this proportion was influenced by parity (time x parity interaction; = 0.006). As a result, proportionally more ( < 0.001) cows received the timed AI at 75 than 85 h (59.4% vs. 40.6%). Similar proportions of cows not in estrus by 55 or 65 h were detected in estrus by 75 or 85 h (40.1% vs. 39.3%), respectively. The cumulative proportion of cows in estrus by 75 h was less ( < 0.001) than that by 85 h (66.7% vs. 76.7%), respectively. Pregnancy risks at 36 d differed among treatments, with cows detected in estrus and inseminated at 55 or 65 h having greater pregnancy risks than their time-inseminated herd mates at 75 or 85 h (62.3% vs.49.7%), respectively. Overall pregnancy risk for cows in the 65+85-h treatment combination was greater at 36 d than for cows in the 55 + 75-h treatment combination (61.0% vs. 51.4%), respectively. We conclude that the 65 + 85-h treatment combination produced more pregnancies than the 55 + 75-h combination, but its implementation may be somewhat less convenient in terms of cow handling times.

Gonadotropin-releasing hormone increased pregnancy risk in suckled beef cows not detected in estrus and subjected to a split-time artificial insemination program.

We hypothesized that GnRH would increase pregnancy risk (PR) in a split-time AI program for cows in which estrus was not detected. A total of 1,236 suckled beef cows at 12 locations in 3 states (Colorado, Kansas, and North Dakota) were enrolled. Before applying the fixed-time AI program, BCS was assessed. Cows were treated on d -7 with a progesterone insert concurrent with 100 µg GnRH and on d 0 with 25 mg PGF plus removal of the insert. Estrus-detection patches were affixed to cows at insert removal. Estrus was defined to have occurred when an estrus-detection patch was >50% colored (activated). Cows in estrus by 65 h ( = 758; 61.3% of all cows) were randomly allocated to 2 treatments: 1) 100 µg GnRH and early + GnRH (E+G; = 373) or 2) AI only at 65 h (early - no GnRH [E-G]; = 385). The remaining cows were randomly allocated to 2 treatments: 1) 5(L+G; = 252) or 2) AI only at 84 h (late no GnRH [L-G]; = 226). Pregnancy was determined 35 d after AI via transrectal ultrasound. Pregnancy risk did not differ ( = 0.68) between E+G and E-G cows (61.9 vs. 60.4%, respectively). Conversely, for cows inseminated at 84 h, PR was greater ( = 0.01) in cows that received GnRH (L+G) compared with their herd mates not receiving GnRH (L- G; 41.7 vs. 30.8%, respectively). Of those cows not detected in estrus by 65 h, 42.1% were detected by 84 h, for a total expression of estrus by all cows of 77.6%. Administration of GnRH increased ( < 0.01) PR in cows not detected in estrus by 84 h (+GnRH = 33.4% [ = 146] vs. no GnRH = 15.0% [ = 128]) but had no effect in cows expressing estrus by 84 h (+GnRH = 65.3% [ = 103] vs. no GnRH = 61.7% [ = 97]). Neither estrus expression by 65 or 84 h nor PR was influenced by BCS, parity, or days postpartum at AI. Cows had greater PR when they had been detected in estrus before AI, and PR was improved by administration of GnRH at 65 h after insert removal in cows that were not detected in estrus and inseminated at 84 h.