Estimados colegas, éste es el primer número de - FMVZ-UNAM

AÑO 1, NÚMERO 1, SEPTIEMBRE 2007 Estimados colegas, éste es el primer número de Noticias de Reproducción Bovina, publicación que tiene como propósito…

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Developmental Biology

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AÑO 1, NÚMERO 1, SEPTIEMBRE 2007 Estimados colegas, éste es el primer número de Noticias de Reproducción Bovina, publicación que tiene como propósito ofrecer información para los Médicos Veterinarios Zootecnistas que están trabajando en el manejo reproductivo de hatos bovinos tanto lecheros como de carne. La información contenida proviene de publicaciones científicas periódicas de alto nivel y también de artículos de difusión técnica escritos por especialistas. Aquí podrán encontrar los resúmenes y la referencia para la consulta del artículo completo. La selección de la información está a cargo de los editores y se hace de acuerdo con el criterio de la utilidad práctica de la misma. El objetivo al iniciar con el primer número es ofrecer una publicación bimestral, la cual llegará en forma electrónica a los colegas inscritos en nuestras bases de datos y a todos aquellos que nos escriban solicitándola. Esta es una publicación sin fin de lucro y su único objetivo es ofrecer información actualizada para mejorar el desempeño de los Veterinarios y con ello contribuir al aumento de la productividad de los hatos bovinos de nuestro país. Editores: Dr. Joel Hernández Cerón y MC Alvaro Ortega León Departamento de Reproducción Facultad de Medicina Veterinaria y Zootecnia Universidad Nacional Autónoma de México value (NPV) than conventional artificial Journal of Dairy Science 2007;90:2569–2576 insemination (AI) breeding schemes, indicating which breeding scheme is advisable under various EXPECTED NET PRESENT VALUE OF PURE AND MIXED scenarios. Budgets were developed to calculate SEXED SEMEN ARTIFICIAL INSEMINATION STRATEGIES IN the expected NPV of various AI breeding DAIRY HEIFERS strategies incorporating conventional (non-sexed) N. J. Olynk and C. A. Wolf and sexed semen. In the base budgets, heifer and Sexed semen has been a long-anticipated tool for bull calf values were held constant at $500 and dairy farmers to obtain more heifer calves, but $110, respectively. The percentage of heifers challenges exist for integrating sexed semen into expected to be born after breeding with commercial dairy farm reproduction programs. conventional and sexed semen used was 49.2 and The decreased conception rates (CR) experienced 90%, respectively. Breeding costs per AI were with sexed semen make virgin heifers better held constant at $15.00 per AI for conventional suited for insemination with sexed semen than semen and $45.00 per AI for sexed semen of lactating dairy cows. This research sought to approximately the same genetic value. identify when various sexed semen breeding Conventional semen CR of 58 and 65% were strategies provided higher expected net present used, and an AI submission rate was set at 100%. Breeding strategies with sexed semen were assessed for breakeven heifer calf values and Journal of Dairy Science 2007;90:1477–1485 sexed semen costs to obtain a NPV equal to that achieved with conventional semen. Breakeven DIETARY ENERGY SOURCE IN DAIRY COWS IN EARLY LACTATION: METABOLITES AND METABOLIC HORMONES heifer calf values for pure sexed semen strategies with a constant 58 and 65% base CR in which A. T. M. van Knegsel, H. van den Brand, E. A. M. Graat, J. Dijkstra, R. Jorritsma, E. Decuypere, S. Tamminga, and B. Kemp sexed semen achieved 53% of the base CR are $732.11 and $664.26, respectively. Breakeven Negative energy balance-related metabolic sexed semen costs per AI of $17.16 and $22.39, disorders suggest that the balance between compared with $45.00 per AI, were obtained to available lipogenic and glucogenic nutrients is obtain a NPV equal to that obtained with pure important. The objectives of this study were to conventional semen for base CR of 58 and 65%, compare the effects of a glucogenic or a lipogenic respectively. The strategy employing purely sexed diet on liver triacylglycerides (TAG), metabolites, semen, with base CR of both 58 and 65%, yielded and metabolic hormones in dairy cows in early a lower NPV than purely conventional semen in all lactation and to relate metabolite concentrations but the best-case scenario in which sexed semen to the determined energy retention in body mass provides 90% of the CR of conventional semen. (ER). Sixteen dairy cows were fed either a Other potential advantages of sexed semen that lipogenic or glucogenic diet from wk 3 prepartum were not quantified in the scenarios include to wk 9 postpartum (pp) and were housed in biosecurity-related concerns, decreased dystocia climate respiration chambers from wk 2 to 9 pp. due to increased numbers of heifer calves, and Diets were isocaloric (net energy basis). implications for internal herd growth. Postpartum, cows fed a lipogenic diet tended to have higher nonesterified fatty acid concentration (NEFA; 0.46 ± 0.04 vs. 0.37 ± 0.04 mmol/L) and lower insulin concentration (4.0 ± 0.5 vs. 5.5 ± 0.6 ± IU/mL). No difference was found in plasma glucose, β-hydroxybutyrate, insulin-like growth Theriogenology 2007;67:1256–1261 factor-I, and thyroid hormones. Liver TAG was CORPUS LUTEUM SIZE AND FUNCTION FOLLOWING equal between both diets in wk −2 and 2 pp. In SINGLE AND DOUBLE OVULATIONS IN NON-LACTATING wk 4 pp cows fed the glucogenic diet had DAIRY COWS numerically lower TAG levels, although there was G.E. Mann, R.S. Robinson, M.G. Hunter no significant dietary effect. Negative relationships Data was collated from a number of studies on were detected between ER and milk fat and various aspects of luteal function in non-lactating between ER and NEFA. A positive relationship was dairy cows to allow comparisons to be made detected between ER and insulin concentration. between single and double ovulating animals. In Overall, results suggest that insulin plays a these studies, estrous cycles had been regulating role in altering energy partitioning synchronized and animals slaughtered on day 5 or between milk and body tissue. Feeding lactating 8. The overall incidence of double ovulations was dairy cows a glucogenic diet decreased 28.3%. Double ovulation was associated with mobilization of body fat compared with a lipogenic smaller individual corpora lutea but no difference diet. The relative abundance of lipogenic in total weight of luteal tissue or any aspect of nutrients, when feeding a more lipogenic diet, is luteal tissue function or plasma concentrations of related to more secretion of lipogenic nutrients in progesterone. Furthermore, in a sub set of milk, lower plasma insulin, and higher plasma animals, there was no difference in preovulatory NEFA concentration. follicle characteristics or plasma concentrations of estradiol around ovulation. These results demonstrated a high incidence of double ovulation in non-lactating cows that had no influence on circulating progesterone concentrations. Animal 2007;1:335–346 Theriogenology 2007;67:486–493 EFFECT OF CHANGES IN DIET ENERGY DENSITY ON FEED EARLY PREGNANCY DIAGNOSIS BY PALPATION PER INTAKE, MILK YIELD AND METABOLIC PARAMETERS IN RECTUM: INFLUENCE ON EMBRYO/FETAL VIABILITY IN DAIRY COWS IN EARLY LACTATION DAIRY CATTLE N. I. Nielsen, N. C. Friggens, T. Larsen, J. B. Andersen, M. O. Juan E. Romano, James A. Thompson, Duane C. Kraemer, Mark E. Nielsen, K. L. Ingvartsen Westhusin, David W. Forrest, Michael A. Tomaszweski The purpose of this experiment was to investigate The objective was to estimate the effect of how early lactating cows adjust their metabolism palpation per rectum (for early pregnancy and production to acute, but moderate changes in diagnosis) on embryo/fetal viability in dairy cattle. the energy density of the diet. Sixty dairy cows A controlled, randomized block-design experiment were randomly assigned to one of four with two blocks, one by category, and the other treatments: two change-over groups (HNH and by number of embryos, was conducted. Five- NHN) and two control groups (HHH and NNN), hundred-and-twenty pregnant dairy cows and where H and N refer to a high and normal energy heifers with a viable embryo detected by density in the total mixed ration (TMR), transrectal ultrasonography (TRUS) between days respectively. The experimental period covered the 29 and 32 after AI were included. The pregnant first 9 weeks post calving, which was split up in females were randomly allocated into two nearly three 3-week periods. Thus, cows assigned to equal groups: palpation per rectum (PAL group; n HNH or NHN shifted TMR in weeks 4 and 7 after = 258) and no palpation per rectum (NPAL group; calving while cows assigned to HHH or NNN were n = 262). The PAL group was submitted to fed the same TMR for all 9 weeks. Results from palpation per rectum (PPR) using the fetal cows on treatment HNH were compared with membrane slip (FMS) technique once between group HHH while cows on treatment NHN were days 34 and 41 of pregnancy. The fetal compared with group NNN. When the diet membrane slip consisted of compressing the changed from N to H and H to N, cows increased pregnant uterine horn and allowing the and decreased their dry-matter intake (DMI), chorioallantoic membrane to slip between the respectively compared with control groups. Cows fingers. Both groups were submitted to two adjusted milk yield accordingly to changes in DMI, additional TRUS at days 45 and 60 of pregnancy, although not always significantly. Energy- to monitor the potential immediate and delayed corrected milk yield was not significantly affected deleterious effects of PPR on embryo and fetal by any of the changes in the energy density of the viability, respectively. A diagnosis of embryo/fetal diet but generally showed same tendencies as death was made when there was no embryo/fetal milk yield. Non-esterified fatty acids (NEFA), beta- heart beat or the absence of positive signs of hydroxybutyrate in blood and milk and pregnancy in an animal previously diagnosed triacylglycerol and glycogen content in the liver pregnant, or the presence of signs of embryo/fetal were not significantly affected by changes in the degeneration. The overall rate of embryo/fetal energy density of the diet, except from NEFA at death was 14.0% (73/520). Embryonic death one change. Glucose increased more when the (10%; 52/520) was higher than fetal death diet changed from N to H and increased less when (4.5%; 21/468; P 0.001). Embryo/fetal the diet changed from H to N, compared with mortality was higher in cows (16.4%; 59/360) control groups, although not always significantly. than in heifers (8.8%; 14/160; P 0.025) and in Collectively, these results suggest that cows cattle with twin (25.5%; 12/47) versus singleton adjust their DMI and partly milk yield according to pregnancies (12.9%; 61/473; P 0.025), but was the energy density of the diet and therefore only not different (P 0.05) between PAL (14.7%; limited effects were observed in physiological 38/258) and NPAL (13.4%; 35/262). In parameters. conclusion, PPR between days 34 and 41 of pregnancy using the fetal membrane slip technique did not affect embryo/fetal viability. a monensin controlled release capsule were Journal of Dairy Science 2007;90:649–658 analyzed to investigate the association between circulating serum β-hydroxybutyrate (BHBA) RELATIONSHIPS AMONG MILK PRODUCTION, ENERGY concentration in the periparturient period and BALANCE, PLASMA ANALYTES, AND REPRODUCTION IN subsequent reproductive performance. Overall, HOLSTEIN-FRIESIAN COWS accounting for both repeated measures within J. Patton, D. A. Kenny, S. McNamara, J. F. Mee, F. P. O’Mara, M. G. cow and clustering at the herd level, non- Diskin, and J. J. Murphy pregnant cows after first insemination tended to Associations were examined between components have increased circulating BHBA concentrations and indicators of early lactation energy balance from 3 wk before calving to 9 wk after calving (EB) and measures of fertility in Holstein cows. relative to pregnant cows. Including the Milk production, dry matter intake (DMI), body interaction between the week of sample collection condition score (BCS), and endocrine and and pregnancy outcome, non-pregnant cows had metabolite data from 96 cows were analyzed higher circulating BHBA concentrations in the using multivariate logistic regression and survival second week after calving than cows diagnosed analysis. Fertility variables investigated were pregnant after first artificial insemination. Within interval to commencement of luteal activity (C- individual weeks, cows with circulating BHBA LA), calving to conception interval (CCI), and concentrations ≥1,000 _mol/L in the first week conception rate to first service (CON1). Mean daily postpartum were less likely to be diagnosed EB, milk protein content, and DMI during the first pregnant after first insemination. In the second 28 d in milk were associated positively with CON1. week postpartum, the cows with circulating BHBA Cows having poorer BCS (≤2.25) at first service concentrations ≥1,400 _mol/L were significantly had a lower CON1. Positive associations were less likely to be pregnant after first artificial identified among EB, milk protein content, DMI, insemination. A dose response relationship was and the likelihood of a shorter interval to C-LA. found when a comparison of the probability of Cows having greater DMI and a more positive EB pregnancy after first insemination and duration of had an increased likelihood of a shorter CCI, elevated circulating ketone bodies was whereas a lower nadir BCS was associated with an investigated. The probability of pregnancy was increased likelihood of a longer CCI. Milk yield was reduced by 20% in cows diagnosed subclinically not associated with any of the fertility variables ketotic in either the first or second week investigated. A greater plasma concentration of postpartum. Nevertheless, cows above the insulin-like growth factor I (IGF-I) during the first subclinical ketosis threshold in both the first and 2 wk of lactation was associated with a greater second week postpartum were 50% less likely to CON1 and an increased likelihood of a shorter be pregnant after first insemination. Similarly, the interval to C-LA. In conclusion, we identified DMI median time to pregnancy increased in cows as the principal component of EB influencing experiencing elevated BHBA concentrations in subsequent fertility. Furthermore, results indicate either (124 d) or both (130 d) the first and second that milk protein content and plasma IGF-I week postpartum relative to cows never concentration in early lactation may be useful experiencing elevated BHBA concentrations indicators of reproductive efficiency. (108d). To further investigate this, the effect of elevated circulating BHBA was permitted to vary with time. The effect decreased with time, such that the daily probability of pregnancy increased similar to nonsubclinically ketotic cows by Journal of Dairy Science 2007;90:2788–2796 approximately 160 d in milk. From this analysis, both the relative circulating concentration of BHBA THE EFFECT OF SUBCLINICAL KETOSIS IN EARLY and the duration of elevated circulating BHBA LACTATION ON REPRODUCTIVE PERFORMANCE OF were negatively associated with the probability of POSTPARTUM DAIRY COWS pregnancy at first service. R. B. Walsh, J. S. Walton, D. F. Kelton, S. J. LeBlanc, K. E. Leslie, and T. F. Duffield Data generated from 796 Holstein cows enrolled in a clinical trial to investigate the health effect of stage in vitro. Embryo quality was assessed by Theriogenology 2007;67:346–352 differential staining of Day 8 blastocysts. The high-fat diet reduced numbers of small and ARTIFICIAL INSEMINATION INCREASES THE PROBABILITY medium follicles. There was no effect on the OFA MALE CALF IN DAIRY AND BEEF CATTLE quality of oocytes (grades 1–4) or cleavage rate. D.P. Berry, A.R. Cromie However, high fat significantly improved The objective of this study was to determine if blastocyst production from matured (P, 0.005) natural mating affected secondary sex ratio. Data and cleaved (P, 0.05) oocytes. Blastocysts from consisting of 642,401 calving records from the the high-fat group had significantly more total, Irish national database, during the years 2002– inner cell mass and trophectoderm cells than the 2005, were used in the analysis. Factors affecting low-fat group (P, 0.05). Regression analysis the logit of the probability of a male calf being showed negative effects of milk yield (P, 0.001), born were determined using multiple regression dry matter intake (P, 0.001), metabolizable generalised estimating equations with sire of the energy intake (P, 0.005), and starch intake (P, calf included as a repeated effect. Month of the 0.001) on blastocyst production in the low-fat year at calving, sex of the previous calf born group but not in the high-fat group. Within the within dam, breed of service sire, parity of dam low-fat group, blastocyst production was and type of mating (i.e., natural or artificial negatively related to growth hormone (P, 0.05) insemination) significantly (P 0.05) affected the and positively related to leptin (P, 0.05). The likelihood of a male calf being born. Male calves lowfat group had higher nonesterified fatty acids were more likely to be born in the warmer months than the high-fat group (P, 0.05). In conclusion, of the year, when the sex of the previous calf higher milk yields were associated with reduced born to the same dam was male, in older cows developmental potential of oocytes in cows given and when the service sire was a beef breed. No a low-fat diet. Provision of a high-fat diet buffered significant interaction between the main effects oocytes against these effects, resulting in existed. The odds of a male calf being born, significantly improved developmental potential. following adjustment for confounding effects, varied from 1.04 to 1.08 (P 0.01) across the years of analysis when artificial insemination was used compared to natural mating. This equates to a 1% unit increase in the probability of a male calf Reproduction 2007;133:155–163 being born following artificial insemination. RELATIONSHIP BETWEEN METABOLIC HORMONES AND OVULATION OF DOMINANT FOLLICLE DURING THE FIRST FOLLICULAR WAVE POST-PARTUM IN HIGH-PRODUCING DAIRY COWS Chiho Kawashima, Saori Fukihara, Mayumi Maeda, Etsushi Kaneko, Biology of Reproduction 2007;77:9–17 Carlos Amaya Montoya, Motozumi Matsui, Takashi Shimizu, Nobuyoshi Matsunaga, Katsuya Kida, Yoh-Ichi Miyake, Dieter Schams IMPACT OF DIETARY FATTY ACIDS ON OOCYTE QUALITY and Akio Miyamoto AND DEVELOPMENT IN LACTATING DAIRY COWS Recent studies suggest that IGF-I is a crucial Ali A. Fouladi-Nashta, Carlos G. Gutierrez, Jin G. Gong, Philip regulatory factor in follicular growth during early C. Garnsworthy, and Robert Webb post-partum period. The aim of the present study The purpose of this study was to examine the was to determine in detail the changing profiles of effects of level of rumen inert fatty acids on metabolic and reproductive hormones in relation developmental competence of oocytes in lactating to ovulation of the dominant follicle (DF) of the dairy cows. Estrous cycles were synchronized in first follicular wave post-partum in high-producing 22 cows on a silage-based diet supplemented with dairy cows. Plasma concentrations of related either low (200 g/day) or high (800 g/day) fat. A hormones in 22 multiparous Holstein cows were total of 1051 oocytes were collected by measured from 4 weeks pre-partum to 3 weeks ultrasound-guided ovum pickup (OPU) in seven post-partum, and the development of DF was sessions/cow at 3–4 day intervals. Oocytes were observed with colour Doppler ultrasound. Thirteen matured, fertilized, and cultured to the blastocyst cows showed ovulation by 15.2 days post-partum. Anovulatory cows showed higher GH and lower reinsertion of IVDs for
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