Reprod Dom Anim. 2017;1–8. wileyonlinelibrary.com/journal/rda | 1 © 2017 Blackwell Verlag GmbH Received: 14 November 2016 | Accepted: 8 March 2017 DOI: 10.1111/rda.12981 ORIGINAL ARTICLE Endometrial gene expression in primiparous dairy cows at the end of the voluntary waiting period is affected by nutrition: Total mixed ration vs increasing levels of herbage allowance AL Astessiano 1 | M Carriquiry 1 | DA Mattiauda 1 | ML Adrien 2 | P Chilibroste 1 | A Meikle 2 1 School of Agronomy, Universidad de la República, Montevideo, Uruguay 2 School of Veterinary Medicine, Universidad de la República, Montevideo, Uruguay Correspondence AL Astessiano, School of Agronomy, Universidad de la República, Montevideo, Uruguay. Email: lauaste@gmail.com Funding information Agencia Nacional de Investigación e Innovación, Grant/Award Number: ANII #POS_2011_1_3577 Contents The study postulated that differential nutritional management during the early lacta- tion period would be reflected in endometrial expression of genes related to embryo growth at the end of the voluntary waiting period. Thus, the effect of the combined use of total mixed ration (TMR) and grazing under different herbage allowances during the first 75 days post-partum (DPP) on endometrial gene expression was evaluated in primiparous dairy cows. Cows were blocked by body weight, age and body condition score and randomly assigned to three grazing treatments: high (HA, 30 kg DM per cow per day), medium (MA, 15 kg DM per cow per day) and low (LA, 7.5 kg DM per cow per day) herbage allowance (mixed pasture, 2,600 kg DM per ha) plus 8 kg DM of supple- ment or TMR (55% forage, 45% concentrate) fed ad libitum (TMR) from calving to 75 DPP. At 57 DPP, cows were synchronized for oestrus (day 0, 68 DPP) and at day 7, endometrial biopsies were obtained. The nutritional treatment did not affect insulin, IGF-1 and leptin concentrations on days 0, 4 or 7. Expression of IGF1, IGFBP3, IGFBP4, ADIPOR1 and ADIPOR2 mRNA was significantly affected by the nutritional treatment. Endometrial IGF1 and IGFBP4 mRNA were twofold greater in TMR and HA than MA and LA cows. Expression of IGFBP3 and ADIPOR1 mRNAs was greater in TMR and HA than MA cows, but did not differ from LA cows. All groups had greater expression of ADIPOR2 mRNA than MA cows. This study provided solid evidence of the importance of nutritional management during early lactation on uterine environment at the end of the voluntary waiting period. The greater expression of genes related to embryo growth and uterine function (IGF system, progesterone and adiponectin receptors) in cows fed diets maximizing energy intake suggests a favourable environment for em- bryonic growth, which may explain the improved reproductive performance of cows in good energy balance. 1 | INTRODUCTION Reproductive performance of high-yielding dairy cows underwent a major decline during the last 50 years of the 20th century (1950 to 2000; Butler, Cummins, & Moore, 2015); more recently selecting for improved fertility has halted this continuous decline and has even started to improve (Norman, Wright, Hubbard, Miller, & Hutchison, 2009). The reproductive success after calving is limited by the re- sumption to ovarian cyclicity and the early embryo mortality which are both affected by the typical negative energy balance of early lacta- tion (Santos, Thatcher, Chebel, Cerri, & Galvão, 2004). It is known that pregnancy establishment is vulnerable during the period of maternal