The objectives were to characterize the prevalence of periparturient diseases and their effects on reproductive performance of dairy cows in seasonal grazing farms. A total of 957 multiparous cows in 2 farms (555 in farm A and 402 in farm B) were evaluated and diseases characterized. At calving, dystocia, twin birth, stillbirth, and retained fetal membranes were recorded and grouped as calving problems. On d 7±3 and 14±3 postpartum, cows were evaluated for metritis and on d 28±3 for clinical endometritis based on scoring of the vaginal discharge. From parturition to 30 d after artificial insemination (AI), prevalence of mastitis, lameness, and digestive and respiratory problems were recorded. For subclinical diseases, diagnosis was based on blood samples collected from 771 cows and analyzed for concentrations of Ca, nonesterified fatty acids (NEFA), and β-hydroxybutyrate. Cows were considered as having elevated NEFA concentration if the concentration was ≥0.70 mM, subclinical ketosis if the β-hydroxybutyrate concentration was ≥0.96 mM, and subclinical hypocalcemia if the Ca concentration was ≤2.14 mM. Ovaries were scanned on d 35±3 and 49±3 postpartum for determination of estrous cyclicity. All cows were enrolled in a timed AI program and inseminated on the first day of the breeding season: on average, 86 d postpartum. Overall, 37.5% (359/957) of the cows presented at least 1 clinical disease and 59.0% (455/771) had at least 1 subclinical health problem. Prevalence of individual diseases was 8.5% for calving problems, 5.3% for metritis, 15.0% for clinical endometritis, 13.4% for subclinical endometritis, 15.3% for mastitis, 2.5% for respiratory problems, 4.0% for digestive problems, 3.2% for lameness, 20.0% for elevated NEFA concentration, 35.4% for subclinical ketosis, and 43.3% for subclinical hypocalcemia. Clinical and subclinical diseases had additive negative effects on reproduction, delaying resumption of estrous cyclicity and reducing pregnancy per AI (P/AI). Occurrence of multiple diseases further reduced reproductive efficiency compared with a single disease. Individually, subclinical hypocalcemia, elevated NEFA concentration, metritis, and respiratory and digestive problems reduced estrous cyclicity by d 49 postpartum. Elevated NEFA concentration, calving problem, metritis, clinical and subclinical endometritis, and digestive problems reduced P/AI on d 65 after AI. Moreover, calving problems and clinical endometritis increased the risk of pregnancy loss between gestation d 30 and 65. Serum concentrations of Ca and NEFA were negatively correlated, and both were associated with prevalence of uterine diseases. In conclusion, periparturient diseases were highly prevalent in seasonally calving grazing dairies and affected cows had delayed resumption of estrous cyclicity, reduced P/AI, and increased risk of pregnancy loss.

Objectives were to investigate 2 intervals from induction of ovulation to artificial insemination (AI) and the effect of supplemental progesterone for resynchronization on fertility of lactating dairy cows subjected to a 5-d timed AI program. In experiment 1, 1,227 Holstein cows had their estrous cycles presynchronized with 2 injections of PGF(2α) at 46 and 60 d in milk (DIM). The timed AI protocols were initiated with GnRH at 72 DIM, followed by 2 injections of PGF(2α) at 77 and 78 DIM and a second injection of GnRH at either 56 (OVS56) or 72h (COS72) after the first PGF(2α) of the timed AI protocols. All cows were time-inseminated at 72h after the first PGF(2α) injection. Pregnancy was diagnosed on d 32 and 60 after AI. In experiment 2, 675 nonpregnant Holstein cows had their estrous cycles resynchronized starting at 34 d after the first AI. Cows received the OVS56 with (RCIDR) or without (RCON) supplemental progesterone, as an intravaginal insert, from the first GnRH to the first PGF(2α). Pregnancy diagnoses were performed on d 32 and 60 after AI. During experiment 2, subsets of cows had their ovaries scanned by ultrasonography at the first GnRH, the first PGF(2α), and second GnRH injections of the protocol. Blood was sampled on the day of AI and 7 d later, and concentrations of progesterone were determined in plasma. Cows were considered to have a synchronized ovulation if they had progesterone <1 and >2.26 ng/mL on the day of AI and 7 d later, respectively, and if no ovulation was detected between the first PGF(2α) and second GnRH injections during resynchronization. In experiment 1, the proportion of cows detected in estrus at AI was greater for COS72 than OVS56 (40.6 vs. 32.4%). Pregnancy per AI (P/AI) did not differ between OVS56 (46.4%) and COS72 (45.5%). In experiment 2, cows supplemented with progesterone had greater P/AI compared with unsupplemented cows (51.3 vs. 43.1%). Premature ovulation tended to be greater for RCON than RCIDR cows (7.5 vs. 3.6%), although synchronization of the estrous cycle after timed AI was similar between treatments. Timing of induction of ovulation with GnRH relative to insemination did not affect P/AI of dairy cows enrolled in a 5-d timed AI program. Furthermore, during resynchronization starting on d 34 after the first AI, supplementation with progesterone improved P/AI in cows subjected to the 5-d timed AI protocol.

No abstract

The objectives were to evaluate the effect of supplementing saturated or unsaturated long-chain fatty acids (FA) to nulliparous and parous Holstein animals (n=78) during late gestation on FA profile of colostrum and plasma of newborn calves and on production and absorption of IgG. The saturated FA supplement (SAT) was enriched in C18:0 and the unsaturated FA supplement (ESS) was enriched in the essential FA C18:2n-6. Fatty acids were supplemented at 1.7% of dietary dry matter to low-FA diets (1.9% of dietary dry matter) during the last 8 wk of gestation. Calves were fed 4 L of colostrum within 2h of birth from their own dam or from a dam fed the same treatment. Feeding fat did not affect prepartum dry matter intake, body weight change, or gestation length. Parous but not nulliparous dams tended to give birth to heavier calves if fed fat prepartum. Parous dams were less able to synthesize essential FA derivatives, as evidenced by lower desaturase indices, compared with nulliparous dams, suggesting a greater need for essential FA supplementation. The FA profile of colostrum was modified to a greater degree by prepartum fat feeding than was that of neonatal calf plasma. The placental transfer and synthesis of elongated n-3 FA (C20:5, C22:5, and C22:6) were reduced, whereas the n-6 FA (C18:2, C18:3, and C20:3) were increased in plasma of calves born from dams fed ESS rather than SAT. Supplementing unsaturated FA prepartum resulted in elevated concentrations of trans isomers of unsaturated monoene and diene FA, as well as C18:2n-6 in colostrum. Serum concentrations of IgG tended to be increased in calves born from dams fed fat compared with those not fed fat, and prepartum feeding of SAT tended to improve circulating concentrations of IgG in newborn calves above the feeding of ESS. Apparent efficiency of absorption of IgG was improved in calves born from dams fed fat, and SAT supplementation appeared more effective than supplementation with ESS. Feeding SAT prepartum may be of greater benefit based upon greater circulating IgG concentrations of calves after colostrum feeding. Feeding moderate amounts of saturated or unsaturated long-chain FA during the last 8 wk of gestation changed the FA profile of colostrum and plasma of neonates to reflect that of the supplements.

The objectives of the current study were to investigate the efficacy of PGF₂α as a therapy to reduce the prevalence of subclinical endometritis and improve pregnancy per artificial insemination (P/AI) in cows subjected to a timed artificial insemination (AI) program. A total of 1,342 lactating Holstein dairy cows were allocated randomly at 25 ± 3 d in milk (DIM) to remain as untreated controls (control, n=454) or to receive a single PGF₂α treatment at 39 ± 3 DIM (1PGF, n=474) or 2 treatments with PGF(α at 25 ± 3 and 39 ± 3 DIM (2PGF, n=414). All cows were enrolled in the double Ovsynch program at 48 ± 3 DIM and were inseminated at 75 ± 3 DIM. A subset of 357 cows had uterine samples collected for cytological examination at 25 ± 3, 32 ± 3, and 46 ± 3 DIM to determine the percentage of polymorphonuclear leukocytes (PMNL). Subclinical endometritis was defined by the presence of ≥ 5% PMNL. Vaginal discharge score was evaluated at 25 ± 3 DIM and used to define the prevalence of purulent vaginal discharge. Body condition score was assessed at 25 ± 3 DIM. Pregnancy was diagnosed 32 d after AI and reconfirmed 28 d later. At 32 ± 3 DIM, the prevalence of subclinical endometritis was reduced by treatment with PGF₂α at 25 ± 3 DIM in 2PGF (control=23.5% vs. 1PGF=28.3% vs. 2PGF=16.7%); however, this benefit disappeared at 46 ± 3 DIM, and 14% of the cows remained with subclinical endometritis. One or 2 treatments with PGF₂α did not influence P/AI on d 32 or 60 after timed AI, which averaged 39.9 and 35.2%. Similarly, treatment with PGF₂α had no effect on pregnancy loss between 32 and 60 d of gestation (11.9%). Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the lowest P/AI and the highest pregnancy loss compared with those diagnosed with only 1 of the 2 diseases or compared with cows having no diagnosis of uterine diseases. Interestingly, subclinical endometritis depressed P/AI and increased pregnancy loss only when it persisted until 46 DIM. On d 32 after AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had greater P/AI than those that remained with subclinical endometritis at 46 DIM (45.4 and 40.0 vs. 25.0%, respectively). Similar to P/AI, cows not diagnosed with subclinical endometritis and those that resolved subclinical endometritis by 46 DIM had less pregnancy loss than those with subclinical endometritis at 46 DIM (9.6 and 13.5 vs. 43.9%, respectively). One or 2 treatments with PGF₂α before initiation of the timed AI program were unable to improve uterine health, P/AI, and maintenance of pregnancy in lactating dairy cows. Cows diagnosed with both purulent vaginal discharge and subclinical endometritis had the greatest depressions in measures of fertility at first AI, particularly when subclinical endometritis persisted in the early postpartum period.

Two experiments evaluated the effects of the first GnRH injection of the 5-d timed artificial insemination (AI) program on ovarian responses and pregnancy per AI (P/AI), and the effect of timing of the final GnRH to induce ovulation relative to AI on P/AI. In experiment 1, 605 Holstein heifers were synchronized for their second insemination and assigned randomly to receive GnRH on study d 0 (n = 298) or to remain as untreated controls (n = 307). Ovaries were scanned on study d 0 and 5. All heifers received a controlled internal drug-release (CIDR) insert containing progesterone on d 0, a single injection of PGF(2α) and removal of the CIDR on d 5, and GnRH concurrent with timed AI on d 8. Blood was analyzed for progesterone at AI. Pregnancy was diagnosed on d 32 and 60 after AI. Ovulation on study d 0 was greater for GnRH than control (35.4 vs. 10.6%). Presence of a new corpus luteum (CL) at PGF(2α) injection was greater for GnRH than for control (43.1 vs. 20.8%), although the proportion of heifers with a CL at PGF(2α) did not differ between treatments and averaged 87.1%. Progesterone on the day of AI was greater for GnRH than control (0.50 ± 0.07 vs. 0.28 ± 0.07 ng/mL). The proportion of heifers at AI with progesterone <0.5 ng/mL was less for GnRH than for control (73.8 vs. 88.2%). The proportion of heifers in estrus at AI did not differ between treatments and averaged 66.8%. Pregnancy per AI was not affected by treatment at d 32 or 60 (GnRH = 52.5 and 49.8% vs. control = 54.1 and 50.0%), and pregnancy loss averaged 6.0%. Responses to GnRH were not influenced by ovarian status on study d 0. In experiment 2, 1,295 heifers were synchronized for their first insemination and assigned randomly to receive a CIDR on d 0, PGF(2α) and removal of the CIDR on d 5, and either GnRH 56 h after PGF(2α) and AI 16h later (OVS56, n = 644) or GnRH concurrent with AI 72 h after PGF(2α) (COS72; n = 651). Estrus at AI was greater for COS72 than for OVS56 (61.4 vs. 47.5). Treatment did not affect P/AI on d 32 in heifers displaying signs of estrus at AI, but COS72 improved P/AI compared with OVS56 (55.0 vs. 47.6%) in those not in estrus at AI. Similarly, P/AI on d 60 did not differ between treatments for heifers displaying estrus, but CO S72 improved P/AI compared with OVS56 (53.0 vs. 44.7%) in those not in estrus at AI. Administration of GnRH on the first day of the 5-d timed AI program resulted in low ovulation rate and no improvement in P/AI when heifers received a single PGF(2α) injection 5 d later. Moreover, extending the proestrus by delaying the final GnRH from 56 to 72 h concurrent with AI benefited fertility of dairy heifers that did not display signs of estrus at insemination following the 5-d timed AI protocol.

CSF2 blocks apoptosis in bovine embryos through actions associated with regulation of genes controlling apoptosis.

2016-10-17T18:53:41