PSXII-22 Relationship between beef cow fertility and maternal immunity

Immunity plays important role in reproduction. There is evidence that maternal immunity changes from a type 1 to a type 2-biased during pregnancy and lack of such a shift may contribute to unsuccessful pregnancy in animals. The objective of the study was to examine the relationship between relative balance between type 1 and type 2 and fertility in suckled beef cows by characterizing relative quantity ratio of IgG 1 and 2 subclasses (IgG1/IgG2). Angus-Hereford cows (n = 394) were synchronized (d0) with a 5-d CIDR protocol. Estrous behavior was monitored using estrus detection aids and visual observation from d5 until AI (d8). On d8 all cows were inseminated at a fixed time and blood samples were collected form to be examined for type1/type/2 ratio and progesterone (P4). A new rapid blood test (D2Dx) was used to assess the type 1/type 2 immunity balance by measuring the relative quantity ratio of IgG1 and IgG2. Pregnancy was determined by ultrasound 48 to 63 days after AI. Overall pregnancy per AI was 51%. Mean relative quantity of IgG1/IgG2 was different (P < 0.05) between non-pregnant and pregnant cows. There was negative relationship between relative IgG/IgG2 ratio and probability of pregnancy to AI (P < 0.05). As IgG1/IgG2 ratio increased, probability of P/AI decreased. Mean relative IgG1/IgG2 ratio was lesser (P < 0.05) in cows detected in estrus vs non-estural cows. There was no correlation between serum P4 concentrations and IgG1/IgG2 ratio. The results indicate that blood IgG1/IgG2 at the time AI has a potential to be used as a marker for pregnancy prediction in beef cows.

Blood Constituents, Antioxidant Activities and Hormonal Profile in She-camels (Camelus dormedarius) during different Physiological Statuses in the North Western Coast of Egypt

To monitor blood constituents and hormonal profiles in dromedary she-camels at different physiological statuses in the Northwestern Coast of Egypt, twenty-four she-camels, aged 7-10 years were used from December 2016 to March 2019. Animals were divided according estrous behavior and ultrasound scans of ovarian structures into estrus and non-estrus groups before natural mating. Pregnancy was diagnosed 30 days after mating by ultrasonography. Blood samples were collected from all animals during estrus and non-estrus and monthly during gestation and lactation periods. During the follicular phase GLC and P4 levels decreased (P<0.05). Levels of E2 and PRL increased (P<0.05). Follicles number and diameter in both ovaries increased (P<0.05) in estrus group. Cyclic status correlated negatively with GLC, P4, total number follicles of left ovary (TLO) and diameter follicles of left ovary (DLO) and positively with AST, E2 and DLO. In 1st trimester of pregnancy, GLC levels decreased. Higher (P<0.05) activity of ALT (2nd and 3rd trimesters) and ALP (1st and 2nd trimesters) were recorded. SOD and HP changed (P<0.05). Pregnancy status correlated negatively with GLC, ALP, HP and SOD and positively with TG and ALT. During lactation, ALB, CHOL, TG, ALT, ALP, P4 and PRL were affected (P<0.05). SOD and HP were higher (P<0.05) in 2nd and 1st trimester, respectively. Lactation status correlated negatively with P4 and PRL and positively with CHOL, ALB, ALP, ALT and TAC. In conclusion, the knowledge the values of hormonal, blood biochemical, antioxidant activities are necessary for diagnostic interpretation of pathological and adjusting the different functions throughout different physiological statuses under arid conditions.

239 Body Weight and Growth in Normal Cyclic and Acyclic Gilts

Anestrus, or failure to express estrus during boar exposure, is commonly observed in replacement gilts, and results primarily from either delayed onset of puberty (prepubertal; PP) or cyclic ovulations without behavioral estrus (behavioral anestrus; BA). Gilts born between 2007 and 2018 at USMARC were observed for age at puberty between 160 and 240 days of age. Mature boars were placed in an alleyway pen while a herdsman observed gilts for standing lordosis in response to the back pressure test. Gilts failing to be observed in estrus by 240 days of age were slaughtered (250.4 ± 0.3 days of age) and reproductive tracts recovered to determine if gilts had ovulated. Gilts were defined as PP (n = 606), BA (n = 649), or Peripubertal (n = 118; PP with large preovulatory follicles on the ovary). There were 96 age-matched, cyclic contemporary gilts included as cyclic control gilts. Body weights were recorded at birth, weaning, 8 weeks, and 21 weeks of age with hot carcass weight (HCW) recorded at slaughter. The objective was to retrospectively determine if growth and HCW differed between these groups. Data were analyzed as a mixed ANOVA using group as a fixed effect with sire and farrowing group to which the gilt was born as random effects. Birth weight, weaning weight, ADG at weaning, and weight at 8 weeks did not differ between groups (P &gt; 0.16). The BA gilts had greater growth rate (weight per day of pig age at 21 weeks; P &lt; 0.02) and HCW (P &lt; 0.0001) than PP and Peripubertal gilts, which also had smaller HCW than control gilts. Some cyclic control gilts (7.3%) that displayed estrous behavior had a prepubertal reproductive tract with no ovulatory activity at slaughter. Results indicated that gilts exhibiting delayed puberty grow slower late in development and during boar exposure. Estrus without ovulation in replacement gilts may be more prevalent than assumed. USDA is an equal opportunity provider and employer.

Attainment and Maintenance of Pubertal Cyclicity May Predict Reproductive Longevity in Beef Heifers†

We hypothesized the manner that heifers achieve puberty may indicate their future reproductive longevity. Heifers with discontinued or delayed cyclicity during puberty attainment may have irregular reproductive cycles, anovulation, and infertility in their first breeding season contributing to a shorter reproductive lifespan. Therefore, plasma progesterone (P4) was measured from weaning to breeding on 611 heifers born 2012–2017 and four pubertal classifications were identified: 1) Early; P4 ≥ 1 ng/ml &lt; March 12 with continued cyclicity, 2) Typical; P4 ≥ 1 ng/ml ≥ March 12 with continued cyclicity, 3) Start-Stop; P4 ≥ 1 ng/ml but discontinued cyclicity, and 4) Non-Cycling; no P4 ≥ 1 ng/ml. Historical herd records indicated that 25% of heifers achieved puberty prior to March 12th in the 10 years prior to the study. Start-Stop and Non-Cycling yearling heifers were lighter indicating reduced growth and reproductive maturity traits compared to Early/Typical heifers. In addition, Non-Cycling/Start-Stop heifers were less responsive to prostaglandin F2 alpha (PGF2α) to initiate estrous behavior and ovulation to be artificially inseminated. Non-Cycling heifers had fewer reproductive tract score-5 and reduced numbers of calves born in the first 21-days-of-calving during their first breeding season. Within the Start-Stop classification, 50% of heifers reinitiated cyclicity with growth traits and reproductive parameters that were similar to heifers in the Early/Typical classification while those that remained non-cyclic were more similar to heifers in the Non-Cycling group. Thus, heifers with discontinued cyclicity or no cyclicity during puberty attainment had delayed reproductive maturity resulting in subfertility and potentially a shorter reproductive lifespan.

Estradiol-17β Pharmacokinetics and Histological Assessment of the Ovaries and Uterine Horns following Intramuscular Administration of Estradiol Cypionate in Feral Cats

The control of feral cats (Felis catus) in Australia is a key biological conservation issue. Male cats are more difficult to control than female cats. Collared and tagged female cats displaying estrous behavior have been considered as a way to lure male cats and reveal their locations. As female cats are seasonal breeders, artificial induction of estrous behavior following the administration of a long-acting estrogen could improve their use for this purpose. Estradiol cypionate was intramuscularly administered to nine entire non-pregnant female feral cats, of unknown estrous status, at 0.1, 0.3, or 0.5 mg/kg. Mean peak serum concentrations of estradiol-17β were 365 pg/mL (0.1 mg/kg), 1281 pg/mL (0.3 mg/kg), and 1447 pg/mL (0.5 mg/kg). The time-course of estradiol-17β concentrations after various doses of estradiol cypionate was assessed using non-compartmental and non-linear mixed-effects methods. At the highest-studied dose (0.5 mg/kg), the 50th percentile of estradiol-17β concentrations exceeded 0.1 ng/mL for 11.8 days, and 0.05 ng/mL for 14.6 days. The duration increased with increasing dose. No signs of toxicity were noticed in any cat during the study. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats.