Two experiments were conducted to determine the effects of immunoneutralization of growth hormone-releasing factor [GRF(1-29)-NH 2 ] on concentrations of somatotropin (ST) and insulin-like growth factor I (IGF-I) in lactating beef cows. In Experiment 1, mUltiparous Hereford cows were immunized against 2 mg GRF(l-29)-(GlY)4-Cys-NH2 conjugated to human serum albumin (GRFi, n=3) or 2 mg human serum albumin (HSAi, n=3) at 52 ± 1 d prior to parturition. Boosters (1 mg) were administered on days 12,40 and 114 postpartum (pp). Serum samples were collected at IS-min intervals for 5 hr on days 18,46 and 120 pp, followed by administration CIV) of an opioid agonist (FK33-824; 10 J..lg/kg) and an antagonist (naloxone; .5 mg/kg) at hours 5 and 7, respectively. A GRF analog ([desamino-Tyrl, D-Ala 2 , Ala l5 ] GRF (l-29)-NH 2 ; 3.5 ~lkg) and arginine (.5 glkg) were administered at hour 10 on days 47 and 121, respectively. Percentage binding of [ 125 I]GRF (1:100 dilution of serum) 28 d after primary immunization was greater in GRFi (14.3 ± 4.9) than in HSAi (.7 ± .3) cows. Binding increased to 29.3 ± 6.5% after first booster in GRFi cows. Episodic release of ST was abolished by immunization against GRF; concentration and frequency of release of ST were lower (P<.05) in GRFi than in HSAi cows on all days pp. Concentrations of IGF-I were lower in GRFi than in HSAi cows throughout lactation. Serum ST failed to increase following FK33-824 or arginine in GRFi; however, ST increased after both compounds in HSAi cows. Concentrations of ST following GRF-analog were greater (P<.05) in HSAi than in GRFi cows. Experiment 2 was con ducted to determine if a lower dose of antigen and a single booster would be sufficient to lower ST and IGF-I in lactating cows. Multiparous Hereford and Angus cows were assigned to GRFi (n=6) or HSAi (n=6). Primary (1.2 mg) and booster (.5 mg) immunizations were administered -14 and 8 d from calving, respectively. Cows were restricted to 60% of recommended intake of energy dur ing lactation in order to elevate concentrations of ST. Serum samples were collected at IS-min in tervals for 6 hr on days 26, 50, 73, 90 and 109 pp. Two of six GRFi cows had binding less than 10% (1 : 1 ,000 dilution of serum) and were omitted from further analyses. Percentage binding at a I: 1,000 dilution was greater in GRFi (17.0 ± 4.7) than in HSAi (1.4 ± .4) cows at 89 d pp. Consequently, frequency of release, and concentration of ST and IGF-I were lower (P < .05) in GRFi than in HSAi cows. Concentrations of ST increased following FK33-824 in HSAi, but not in GRFi cows. Across experiments, interval from calving to ovulation (estimated from weekly progesterone concentrations) was greater in HSAi than in GRFi cows. In conclusion, gestating-lactating beef cows were effec , tively immunized against GRF as evidenced by antibody binding of [ 125 I]GRF, absence of pulsatile release of ST, low concentrations of ST and IGF-I and failure of ST to increase after IV opioid ago nist or arginine.

L ong-acting reversible contraceptives (LARCs) comprise intrauterine contraception, ie the copper intrauterine device (Cu-IUD) and the levonorgestrel-releasing intrauterine system (IUS); the progestogen-only implant; and progestogen-only injections. They do not depend on user reliability or affect long-term fertility, they are highly effective (typical failure rate less than 1%), cost-effective and have non-contraceptive benefits, and yet use is still relatively low.In England in 2020/21, among women in contact with sexual and reproductive health services, 46% were using LARCs compared to user-dependent contraceptives such as the pill or condoms. 1 Figures from 2017/18 showed that almost nine in 10 women who received contraception from GPs or pharmacies in England took either the combined pill or 'mini pill', with the proportion remaining similar over the previous three years. 2 There are thought to be many reasons for the low uptake of LARCs, including GP time pressures not allowing a thorough enough discussion to take place, misconceptions held by GPs (for example misidentifying major risk such as ectopic pregnancy, incorrect views about eligibility of nulliparous women or those with a history of pelvic inflammatory disease), reduction in access to the procedures within primary care or community clinics, and the scrapping of the Quality and Outcomes Framework financial incentive for giving advice about LARCs. 3 NICE states that women asking for contraception must be given information about, and offered a choice of, all methods including LARCs. 4 LARCs are also often suitable alternatives for those in whom the combined oral contraceptive pill is contraindicated.In 2016, Public Health England estimated that if 1000 women switched from oral contraceptives to LARCs, 291 unplanned pregnancies could be avoided over five years. This equates to an average net saving to the NHS of £29 per annum per woman. 3

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Introduction Growth and carcass trait EBVs have been produced for the UK beef industry since the 1990's, with maternal 200 day milk being the only EBV available for female fertility (FF). To provide the UK beef industry with direct and maternal EBVs for FF traits a research project was undertaken to consider trait definitions, model development and genetic parameter estimation (Roughsedge et al., 2005a). Limousin heritability estimates from the study were generally low, ranging from 0.04 (calving interval (CI)) to 0.27 (age at first calving (AFC)). Being sex-limited traits means that sires have to wait until their daughters reproduce until performance information is available for a sire. Consequently, the sire is often approximately 5 years of age by the time daughter performance records for FF traits are available for use in genetic evaluation. For carcass traits, the sires own performance information is known at approximately 1-2 years of age. The generally low heritabilities and performance records of daughters only available late in life means that sires are generally older when they receive accurate FF EBVs. Despite these challenges, significant genetic improvement for FF traits is achievable (Roughsedge et al., 2005b). In 2007 the EGENES/Signet genetic evaluations incorporated for the first time EBVs for AFC, CI, calving ease (direct and maternal components), life span and gestation length (direct and maternal components) (Coffey et al. 2007). However, feedback from industry suggests that these FF EBVs have been under utilised in the UK beef industry. The aim of this work was to demonstrate the value of the FF EBVs for breeding replacement cows.