16 t h International Congress on Animal <strong>Reproduction</strong> 66 Poster Abstracts suggests <strong>de</strong>layed oestrus <strong>in</strong>dicative of late embryo <strong>de</strong>ath (after maternal recognition on day 17). This may suggest a sire-specific effect on embryo survival that partly could have a genetic component. Further studies will <strong>in</strong>clu<strong>de</strong> flow cytometric studies of sperm from poor fertility sires. P115 Na + /K + ATPase regulates tyros<strong>in</strong>e phosphorylation and capacitation <strong>in</strong> bov<strong>in</strong>e sperm through multiple signal transduction pathways Thundathil, J 1 *; Newton, L 1 ; Kastelic, J 1,2 ; Wong, B 3 ; van <strong>de</strong>r Hoorn, F 4 1Department of Production Animal Health, Faculty of Veter<strong>in</strong>ary Medic<strong>in</strong>e, University of Calgary, Canada; 2 Lethbridge Research Centre, Agriculture and Agri-Food Canada, Canada; 3 Regional Fertility Program, Calgary Health Region, Canada; 4 Department of Biochemistry and Molecular Biology, University of Calgary, Canada Introduction Cryopreservation prematurely capacitated bov<strong>in</strong>e sperm, reduc<strong>in</strong>g the fertile life-span of sperm <strong>in</strong> the female reproductive tract. Un<strong>de</strong>rstand<strong>in</strong>g the cellular and molecular regulation of sperm capacitation will have implications for improv<strong>in</strong>g the fertility of frozen semen, as well as predict<strong>in</strong>g bull fertility. In somatic cells, <strong>in</strong>hibition of Na + /K + ATPase (a cell membrane prote<strong>in</strong>) with its specific <strong>in</strong>hibitor ouaba<strong>in</strong> <strong>in</strong>itiated cellular responses similar to signall<strong>in</strong>g mechanisms lead<strong>in</strong>g to sperm capacitation, suggest<strong>in</strong>g a role for this prote<strong>in</strong> <strong>in</strong> the regulation of sperm capacitation. Although the α1ß1 isoform of this prote<strong>in</strong> is ubiquitous, α4ß3 is testicular specific; both are sensitive to ouaba<strong>in</strong>. We previously reported that specifically <strong>in</strong>hibit<strong>in</strong>g this prote<strong>in</strong> with ouaba<strong>in</strong> <strong>in</strong>duced tyros<strong>in</strong>e phosphorylation and capacitation <strong>in</strong> bov<strong>in</strong>e sperm. The objective of this study was to <strong>in</strong>vestigate the molecular regulation of tyros<strong>in</strong>e phosphorylation and capacitation <strong>in</strong>duced by <strong>in</strong>hibition of Na + /K + ATPase Methods Fresh sperm from Holste<strong>in</strong> bulls was <strong>in</strong>cubated with specific <strong>in</strong>hibitors of prote<strong>in</strong> k<strong>in</strong>ase A (PKA), prote<strong>in</strong> k<strong>in</strong>ase C (PKC), receptor tyros<strong>in</strong>e k<strong>in</strong>ase (rTK), or non-receptor tyros<strong>in</strong>e k<strong>in</strong>ase (Src), alone or <strong>in</strong> comb<strong>in</strong>ation, for 30 m<strong>in</strong>utes prior to a 4 hours <strong>in</strong>cubation with or without ouaba<strong>in</strong> (100 µM). Sperm preparations were electrophoresced and immunoblotted with anti-phospho-tyros<strong>in</strong>e antibody. Capacitation status of sperm from parallel sperm preparations were <strong>de</strong>term<strong>in</strong>ed, based on their ability to un<strong>de</strong>rgo an acrosome reaction. Results Inhibition of Na + /K + ATPase activity with ouaba<strong>in</strong> <strong>in</strong>itiated tyros<strong>in</strong>e phosphorylation <strong>in</strong> a cohort of sperm prote<strong>in</strong>s and capacitation <strong>in</strong> bov<strong>in</strong>e sperm. However, pre-treatment with <strong>in</strong>hibitors specific for rTK, PKA or PKC partially <strong>in</strong>hibited these processes, suggest<strong>in</strong>g <strong>in</strong>volvement of these signall<strong>in</strong>g molecules. Additionally, there was evi<strong>de</strong>nce of cross-talk between signall<strong>in</strong>g molecules. Simultaneous <strong>in</strong>hibition of Src and rTK or Src, rTK and PKC <strong>in</strong> comb<strong>in</strong>ation resulted <strong>in</strong> greater <strong>in</strong>hibition of tyros<strong>in</strong>e phosphorylation and capacitation than the <strong>in</strong>dividual effects of these <strong>in</strong>hibitors. Conclusion We <strong>in</strong>ferred that Na + /K + ATPase regulated tyros<strong>in</strong>e phosphorylation and capacitation through multiple signall<strong>in</strong>g pathways <strong>in</strong>volv<strong>in</strong>g prote<strong>in</strong> k<strong>in</strong>ase A, prote<strong>in</strong> k<strong>in</strong>ase C, receptor tyros<strong>in</strong>e k<strong>in</strong>ase and nonreceptor tyros<strong>in</strong>e k<strong>in</strong>ase. However, s<strong>in</strong>ce ouaba<strong>in</strong> <strong>in</strong>hibited both α1ß1 and α4ß3 isoforms, the unique role of the testicular specific isoform of Na + /K + ATPase <strong>in</strong> the regulation of sperm function rema<strong>in</strong>s to be elucidated. P116 Effect of different energy sources on milk production, body condition score and reproductive performance of dairy cows dur<strong>in</strong>g the transition period Torres Artunduaga, MA*, Gesteira Coelho, S; Campos, BG; Qu<strong>in</strong>tao Lana, AM; Matana Saturn<strong>in</strong>o, H; Maia Borges, A; Braga Reis, R; Castro Meneses, G Fe<strong>de</strong>ral University of M<strong>in</strong>as Gerais, UFMG, Brazil Introduction Solv<strong>in</strong>g reproductive problems of post partum dairy cows has become one of the ma<strong>in</strong> targets of the scientific community even thought the advances <strong>in</strong> this field are partial <strong>in</strong> most of the conducted research, that is, some work is done with nutrition only and others just focus on reproduction. Today there is a need to get throughout the problem by a multidiscipl<strong>in</strong>ary strategy <strong>in</strong>volv<strong>in</strong>g nutrition and reproduction issues. However, the effects of negative energy balance on reproductive performance have been elucidated and formulation of balanced rations for post partum dairy cows <strong>in</strong> or<strong>de</strong>r to m<strong>in</strong>imize the <strong>de</strong>crease <strong>in</strong> dry matter <strong>in</strong>take and mobilization of body reserves dur<strong>in</strong>g post partum have been utilized, the reproductive efficiency parameters such as conception rate, days open, <strong>in</strong>terval between parturition, among others, still show that dairy farms have this problem without a practical solution. Objective Based on the above mentioned consi<strong>de</strong>rations the objective of this study was to evaluate the effect of the addition of different energy sources such as calcium salts of polyunsaturated fatty acids (Megalac –E), toasted soybean and propylene glycol on milk production, body condition score and reproductive performance of dairy cows dur<strong>in</strong>g the transition period. Material and methods 48 multiparous Holste<strong>in</strong> cows were used on this trial. Cows received the energy sources from 28 days before the expected calv<strong>in</strong>g date until 21 days post partum. Cows were distributed randomly <strong>in</strong> 4 treatments (control, Megalac-E, toasted soybean and propylene glycol). Body condition score was performed at 21 days pre-partum and once per week until 46 days post partum. Milk production was recor<strong>de</strong>d on days 10, 20, 30 and 40 post partum. All cows were scanned us<strong>in</strong>g ultrasound from 10 days post-partum every two days until day 46 post-partum. Before each ultrasound scann<strong>in</strong>g, uter<strong>in</strong>e <strong>in</strong>volution was evaluated and scores were given accord<strong>in</strong>g to position of uterus on cavity and uter<strong>in</strong>e content. Results Milk production for control, Megalac-E, toasted soybean and propylene glycol was 24, 25, 20, and 25 kg respectively. Body condition score between groups did not differed but cows consum<strong>in</strong>g Megalac-E showed the more uniform score through the entire trial. Expulsion of placenta on Megalac –E group was observed at 3,5 hours after parturition. For control, toasted soybean and propylene glycol this average time was 7,5, 9,5 and 4,5 hours after parturition. Cows on control group had their first ovulation after parturition at 29 days while cows receiv<strong>in</strong>g Megalac –E had it with 23 days after <strong>de</strong>livery. The cows fed toasted soybean and propylene glycol had their first ovulation at 30 and 35 days respectively. Conclusions These prelim<strong>in</strong>ary report, <strong>in</strong>dicate that the use of energy sources such as calcium salts of polyunsaturated fatty acids could be advantageous regard<strong>in</strong>g animal health and reproductive performance. P117 Evaluation of strategies to improve cyclicity <strong>in</strong> Bos <strong>in</strong>dicus-<strong>in</strong>fluenced heifers Tribulo, HE 1 *, Chesta, PM 2 , Brandan, A 3 , Cuestas, G 2 , Lozano, P 3 1<strong>Facultad</strong> <strong>de</strong> <strong>Ciencias</strong> Agropecuarias, Universidad Nacional <strong>de</strong> Cordoba, Argent<strong>in</strong>a; 2 Area <strong>de</strong> Investigacion, Instituto <strong>de</strong> Reproduccion Animal Cordoba -IRAC-, Argent<strong>in</strong>a; 3 Produccion, Compania Anglo Cordoba <strong>de</strong> Tierrras SA, Argent<strong>in</strong>a A study was <strong>de</strong>signed to evaluate strategies to <strong>in</strong>crease cyclicity prior to breed<strong>in</strong>g <strong>in</strong> 15 month-old Bos <strong>in</strong>dicus-<strong>in</strong>fluenced heifers. The first experiment evaluated the effect of progesterone (P4) prim<strong>in</strong>g, beg<strong>in</strong>n<strong>in</strong>g 40 or 20 days before breed<strong>in</strong>g. Fifteen month-old, Bos <strong>in</strong>dicus X Bos taurus heifers (n = 547) with body condition scores of 3 to 3.5 (1 to 5 scale) were exam<strong>in</strong>ed by ultrasonography (Chison Vet 500, 5 Mhz) 40 days before (Day -40) and at the beg<strong>in</strong>n<strong>in</strong>g of the breed<strong>in</strong>g season (Day 0) to <strong>de</strong>term<strong>in</strong>e the presence or absence of a CL (cyclicity). Heifers were allocated to one of three treatment groups: an untreated control group and two P4-treated groups that received a P4- releas<strong>in</strong>g vag<strong>in</strong>al <strong>de</strong>vice (0.75 g of P4, Prociclar, Zoovet, Argent<strong>in</strong>a) for 8 days followed by 1 mg estradiol benzoate (Zoovet) at time of <strong>de</strong>vice removal, beg<strong>in</strong>n<strong>in</strong>g 40 or 20 days prior to the breed<strong>in</strong>g season. The percentage of cycl<strong>in</strong>g heifers on Day -40 did not differ among groups (65.6%, 118/180; 65.0%, 115/117 and 66.8%, 127/190 for heifers <strong>in</strong> the P4 on Day -40, P4 on Day -20 or the control groups, respectively). However, the percentage cycl<strong>in</strong>g heifers on Day 0 was significantly higher (P
16 t h International Congress on Animal <strong>Reproduction</strong> Poster Abstracts 67 experiment was <strong>de</strong>signed to compare P4-prim<strong>in</strong>g with the biostimulatory effect of vasectomized bulls beg<strong>in</strong>n<strong>in</strong>g 30 days before the breed<strong>in</strong>g season. The experiment <strong>in</strong>volved 639 15 month-old Bos <strong>in</strong>dicus X Bos taurus heifers from the same farm. Heifers were exam<strong>in</strong>ed by ultrasonography on Days -30 and 0 and allocated <strong>in</strong>to three treatment groups: a P4 treated group that received a Prociclar for 8 days followed by 1 mg of estradiol cypionate (Zoovet) at the time of <strong>de</strong>vice removal, beg<strong>in</strong>n<strong>in</strong>g on Day -30, a group that was exposed to seven vasectomized bulls for 30 days and an untreated control group. The percentage of cycl<strong>in</strong>g heifers on Day -30 did not differ among groups (55.0%, 115/209; 55.7%, 117/210 and 55.5%, 122/220 for P4- prim<strong>in</strong>g, bull-exposed and control groups, respectively). However, the percentage of cycl<strong>in</strong>g heifers on Day 0 was significantly higher (P