Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias

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16 t h International Congress on Animal Reproduction 66 Poster Abstracts suggests delayed oestrus indicative of late embryo death (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 include flow cytometric studies of sperm from poor fertility sires. P115 Na + /K + ATPase regulates tyrosine phosphorylation and capacitation in bovine sperm through multiple signal transduction pathways Thundathil, J 1 *; Newton, L 1 ; Kastelic, J 1,2 ; Wong, B 3 ; van der Hoorn, F 4 1Department of Production Animal Health, Faculty of Veterinary Medicine, 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 bovine sperm, reducing the fertile life-span of sperm in the female reproductive tract. Understanding the cellular and molecular regulation of sperm capacitation will have implications for improving the fertility of frozen semen, as well as predicting bull fertility. In somatic cells, inhibition of Na + /K + ATPase (a cell membrane protein) with its specific inhibitor ouabain initiated cellular responses similar to signalling mechanisms leading to sperm capacitation, suggesting a role for this protein in the regulation of sperm capacitation. Although the α1ß1 isoform of this protein is ubiquitous, α4ß3 is testicular specific; both are sensitive to ouabain. We previously reported that specifically inhibiting this protein with ouabain induced tyrosine phosphorylation and capacitation in bovine sperm. The objective of this study was to investigate the molecular regulation of tyrosine phosphorylation and capacitation induced by inhibition of Na + /K + ATPase Methods Fresh sperm from Holstein bulls was incubated with specific inhibitors of protein kinase A (PKA), protein kinase C (PKC), receptor tyrosine kinase (rTK), or non-receptor tyrosine kinase (Src), alone or in combination, for 30 minutes prior to a 4 hours incubation with or without ouabain (100 µM). Sperm preparations were electrophoresced and immunoblotted with anti-phospho-tyrosine antibody. Capacitation status of sperm from parallel sperm preparations were determined, based on their ability to undergo an acrosome reaction. Results Inhibition of Na + /K + ATPase activity with ouabain initiated tyrosine phosphorylation in a cohort of sperm proteins and capacitation in bovine sperm. However, pre-treatment with inhibitors specific for rTK, PKA or PKC partially inhibited these processes, suggesting involvement of these signalling molecules. Additionally, there was evidence of cross-talk between signalling molecules. Simultaneous inhibition of Src and rTK or Src, rTK and PKC in combination resulted in greater inhibition of tyrosine phosphorylation and capacitation than the individual effects of these inhibitors. Conclusion We inferred that Na + /K + ATPase regulated tyrosine phosphorylation and capacitation through multiple signalling pathways involving protein kinase A, protein kinase C, receptor tyrosine kinase and nonreceptor tyrosine kinase. However, since ouabain inhibited both α1ß1 and α4ß3 isoforms, the unique role of the testicular specific isoform of Na + /K + ATPase in the regulation of sperm function remains to be elucidated. P116 Effect of different energy sources on milk production, body condition score and reproductive performance of dairy cows during the transition period Torres Artunduaga, MA*, Gesteira Coelho, S; Campos, BG; Quintao Lana, AM; Matana Saturnino, H; Maia Borges, A; Braga Reis, R; Castro Meneses, G Federal University of Minas Gerais, UFMG, Brazil Introduction Solving reproductive problems of post partum dairy cows has become one of the main targets of the scientific community even thought the advances in this field are partial in 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 multidisciplinary strategy involving 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 in order to minimize the decrease in dry matter intake and mobilization of body reserves during post partum have been utilized, the reproductive efficiency parameters such as conception rate, days open, interval between parturition, among others, still show that dairy farms have this problem without a practical solution. Objective Based on the above mentioned considerations 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 during the transition period. Material and methods 48 multiparous Holstein cows were used on this trial. Cows received the energy sources from 28 days before the expected calving date until 21 days post partum. Cows were distributed randomly in 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 recorded on days 10, 20, 30 and 40 post partum. All cows were scanned using ultrasound from 10 days post-partum every two days until day 46 post-partum. Before each ultrasound scanning, uterine involution was evaluated and scores were given according to position of uterus on cavity and uterine 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 consuming 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 receiving Megalac –E had it with 23 days after delivery. The cows fed toasted soybean and propylene glycol had their first ovulation at 30 and 35 days respectively. Conclusions These preliminary report, indicate that the use of energy sources such as calcium salts of polyunsaturated fatty acids could be advantageous regarding animal health and reproductive performance. P117 Evaluation of strategies to improve cyclicity in Bos indicus-influenced heifers Tribulo, HE 1 *, Chesta, PM 2 , Brandan, A 3 , Cuestas, G 2 , Lozano, P 3 1Facultad de Ciencias Agropecuarias, Universidad Nacional de Cordoba, Argentina; 2 Area de Investigacion, Instituto de Reproduccion Animal Cordoba -IRAC-, Argentina; 3 Produccion, Compania Anglo Cordoba de Tierrras SA, Argentina A study was designed to evaluate strategies to increase cyclicity prior to breeding in 15 month-old Bos indicus-influenced heifers. The first experiment evaluated the effect of progesterone (P4) priming, beginning 40 or 20 days before breeding. Fifteen month-old, Bos indicus X Bos taurus heifers (n = 547) with body condition scores of 3 to 3.5 (1 to 5 scale) were examined by ultrasonography (Chison Vet 500, 5 Mhz) 40 days before (Day -40) and at the beginning of the breeding season (Day 0) to determine 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- releasing vaginal device (0.75 g of P4, Prociclar, Zoovet, Argentina) for 8 days followed by 1 mg estradiol benzoate (Zoovet) at time of device removal, beginning 40 or 20 days prior to the breeding season. The percentage of cycling heifers on Day -40 did not differ among groups (65.6%, 118/180; 65.0%, 115/117 and 66.8%, 127/190 for heifers in the P4 on Day -40, P4 on Day -20 or the control groups, respectively). However, the percentage cycling heifers on Day 0 was significantly higher (P
16 t h International Congress on Animal Reproduction Poster Abstracts 67 experiment was designed to compare P4-priming with the biostimulatory effect of vasectomized bulls beginning 30 days before the breeding season. The experiment involved 639 15 month-old Bos indicus X Bos taurus heifers from the same farm. Heifers were examined by ultrasonography on Days -30 and 0 and allocated into 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 device removal, beginning on Day -30, a group that was exposed to seven vasectomized bulls for 30 days and an untreated control group. The percentage of cycling heifers on Day -30 did not differ among groups (55.0%, 115/209; 55.7%, 117/210 and 55.5%, 122/220 for P4- priming, bull-exposed and control groups, respectively). However, the percentage of cycling heifers on Day 0 was significantly higher (P
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