Efeito do eCG ou benzoato de estradiol associado ao norgestomet na taxa de concepção de vacas de corte submetidas à IATF no pós-parto

This study aimed to compare conception rates at the postpartum period (PPP) in beef cows which were administered either Equine Chorionic Gonadotrophin (eCG) or Estradiol Benzoate (EB) after Norgestomet and submitted to fixed-time artificial insemination (FTAI). The hypothesis was that the administration of eCG or EB enhances the conception rate. Lactating Nelore cows (n=138) and Brangus (n = 63), between 26 and 118 days of post partum period (PPP) were divided into three homogeneous groups, and subdivided in two blocks, inside each group one of them with a PPP d'' 45 days (PPP1; n=107) and another with a PPP > 45 days (PPP2; n=94). All cows received an auricular implant containing 3mg Norgestomet (Crestar®), followed by the administration of 5mg Estradiol Valerate. The auricular implants were kept during 10 days. Cows received 1mL saline solution (n=68, Control Group) or 500IU eCG (Folligon®; n=67; eCG Group) or 1mg Estradiol Benzoate (Index, n=66; EB Group) 24 hours after the removal of the implant. FTAI was made 54 hours after the implant removal. The pregnancy diagnosis was carried through ultrasonography 30 days after FTAI. There was an interaction between treatments and PPP. In the PPP1, the conception rate was higher in the eCG Group than in the EB Group (47.22% vs. 15.38%; Pd''0.01). In the PPP2, the conception rates of the eCG and EB Groups were higher than in the Control Group (41.93%, 44.44% vs. 22.22%: Pd''0.01). It was concluded that in cows up to 45 days of PPP, the eCG associated with Norgestomet enhances the conception rates.

Efeito da suplementação com semente de girassol na performance reprodutiva de fêmeas bovinas de corte: Mariângela Bueno Cordeiro. -

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Associação de escores de condição corporal com características reprodutivas de vacas Nelore e com desempenho de seus bezerros

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Incidência de perdas gestacionais e efeito da vacinação contra doenças da reprodução nas taxas de prenhez em vacas de corte submetidas à inseminação artificial em tempo fixo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da responsividade hipotalámica-hipofisária durante o pós-parto em vacas nelore

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos da somatotropina recombinante bovina na taxa de concepção, composição celular do corpo lúteo e morfometria das glândulas endometriais em vacas de corte

Pós-graduação em Ciência Animal - FMVA

Suplementação com gordura protegida para vacas de corte desmamadas precocemente mantidas em pastagem natural

The objective of this work was to evaluate the productive and reproductive performance of beef cows, as well as the performance of their calves according to the following dietary treatments: PRE: supplemented with protected fat (PF) during 45 days prepartum; PREPOS: supplemented with PF during 45 days prepartum and 63 days postpartum; POS: supplemented with PF during 63 days postpartum; PN: without supplementation. The productive performance of cows was not influenced by feed management (P>0.05), except for body condition score (BCS), which was lower for PRE and PREPOS cows at the end of mating season, with the latter cows having similar BCS POS and PN. The calving interval (CI) was shorter for cows supplemented in PREPOS - 376 days -, and did not differ in cows maintained in PN - 383 days. Supplemented PREPOS cows weaned 4.4% more pounds of calf per 100kg of cow at calving - 22.6kg - than the PRE and POS cows - 21.6kg and 21.6kg, respectively - and 8,4% more pounds of calf per 100 of cow at calving than the cows maintained in native pasture - 20.7kg. The fat protected supplementation during pre and/or postpartum periods did not affect the performance of cows and calves.

Toll-Like recepctors (TLRs) and retinoic acid inducible gene – I (RIG-I) activation by viral analogs in bovine endometrial cells

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Diâmetro folicular e taxa de prenhez em protocolo de sincronização com GnRH ou Benzoato de Estradiol no dia 0 em vacas de corte

This work aimed to evaluate the pregnancy rate and follicular diameter using EB or GnRH on the insertion of progesterone implant (D0) in lactating beef cows. Two groups were tested in two experiments. In Exp. 1 were used 61 Nelore cows divided into two groups: G-BE (n = 32) and G-GnRH (n = 29), on D0 was inserted P4 implant (CIDR ) and applied 2 mL of BE (G-BE) or 2.5 mL GnRH (G-GnRH). In D9 was performed ultrasonography (U.S.) to measure the diameter of the dominant follicle (DF) present in the ovary and the implant was removed, with concomitant administration of 2.5 mL of PGF2a and estradiol cypionate (ECP ) followed by calves removal. After 48 hours all the cows were inseminated and the calves returned. In Exp. 2 50 cows were used following the same protocol described above, but the pregnancy was assessed without performing ovarian US. There was no difference (p>0.05) in pregnancy rate between treatments, BE (55%) or GnRH (41%), but the follicular diameter was significantly higher (p<0.05) in pregnant cows treated with EB (10.7 mm vs. 8.5 mm) and in cows treated with GnRH there was no difference (p>0.05) between pregnant and no pregnant cows (11.6 mm vs. 10.2 mm). We concluded the use of GnRH on D0 did not improve the pregnancy rate in lactating beef cows and follicular diameter was greater (p <0.05) in pregnant cows compared to non-pregnant only in G-BE.

Strategies for Artificial Insemination of Cattle at Synchronized Ovulation or Synchronized Estrus

Two synchronization protocols in lactating dairy and beef cows and in dairy heifers were tested for efficacy of breeding by artificial insemination (AI) with or without estrus detection. Controls received three prostaglandin F2a (PGF2a) injections 14 days apart before AI at observed estrus. Pregnancy rates were compared with animals on the Ovsynch protocol that combined gonadotropin releasing hormone (GnRH) and PGF2a treatments with a timed AI 16 to 20 hours after the second GnRH injection. The pregnancy rates were similar at synchronized ovulation to fixed-time AI in lactating cows, but not effective in heifers because of the lack of synchronization.

Alternative Cow Herd Investment Strategies: Constant Size and Constant Investment

Two heifer replacement strategies were compared over a 25-year period. One strategy retained the same number of heifers each year to maintain a constant herd size. The second strategy retained the same dollar value of heifer calves each year based on their opportunity cost as feeder calves. The constant investment strategy herd size varied throughout the period, but generated higher average profit and higher net worth than did the constant herd size strategy. Constant investment is a simple strategy to adjust the level of investment in beef cows and the resource base (pasture, labor, winter feed) in response to market signals driven by the cattle cycle. This strategy automatically increases heifer retention when the opportunity cost is low and reduces the number retained when cost is high. The effect is a lower average cost of cows in the herd, lower overall investment, and a higher net return on investment. Iowa producers, who often have greater flexibility in land use than producers in other major beef cow regions, can better utilize this strategy that generates greater profits and net worth growth.

Frequência de microrganismos em conteúdo vulvovaginal de vacas tratadas com dispositivos intravaginais de progesterona

The dissertation was divided in two studies. With the first, aimed to evaluate the occurrence of microorganisms present in the vulvovaginal region of cows that received intravaginal progesterone devices during the fixed-time artificial insemination (FTAI) programs, and correlate the results with pregnancy rates. Samples were collected from vulvovaginal region of 30 beef cows Guzerá and 30 crossbred dairy cows, and also intravaginal devices, randomly. Of the 120 samples of cows, 60 corresponded to the collections of the period prior to the introduction device (D0) and 60 to the subsequent withdrawal of it (D9); it yielded 100% of bacterial growth, whereas, in most samples, it was found more than one isolated. In D0, the most frequent agent was Escherichia coli (52%), and in D9, Proteus spp and E. coli were the most frequent (32% and 28%, respectively). Regarding intravaginal progesterone devices, in D0 were isolated 37 microorganisms, being predominant those of the genus Bacillus (35%); in D9, 41 colony forming units (CFU) were isolated, of which 36.6% corresponded to Proteus spp. For the analysis of the antimicrobial profile, susceptibility testing was performed by diffusion agar disk, and cows that did not became pregnant after FTAI program were selected, as a future treatment. There resistance 100% to penicillin, and sensitivity, approximately, 90% to gentamicin, both isolates obtained from samples of beef cows and obtained of dairy cows. Regarding pregnancy rate, the 30 beef cows, 11 were diagnosed pregnant (36.7%), 4 (36.4%) treated with reused devices and 7 (63.6%) with new devices, which showed more effective. Of the 30 dairy cows, 15 were pregnant (50%), 8 (53.3%) were implanted with reused devices and 7 (46.7%) with new devices, with no significant differences in pregnancy rates. Because it is a research, females were chosen at random, and factors such as body condition, nutritional management and health weren't priority. With the second study, aimed to analyze the similarity between strains, conducted by technical Random Amplified Polymorphic DNA (RAPD -PCR). Presence of E. coli and the absence of pregnancy were selection criteria used. From the results, it was observed that most of the isolates wasn't phylogenetically similar, since they showed lower than 85% similarity. The study stressed the importance of E. coli in vulvovaginal microbiota of cows and the presence of phenotypic and genotypic characters of this bacterium on possible reproductive problems.

Técnicas de manejo agropecuário sustentável

The competitiveness in the rural sector and the need to make viable and sustainable property, direct the farmer to seek new production strategies. In this sense, the book Techniques of sustainable agricultural management has as objective contributed information on concepts, management practices, technological innovations, which are applicable in the agricultural production. The same is composed of 13 chapters, topics covered in aquaculture production, management and dairy production, as general aspects of hematology fish; dynamics of decision-making and adaptive flow dairy production systems; importance of performance measures and body biometrics in small ruminants; milk production in beef cows; parasitism in beef cattle; performance of dairy cows in production; efficiency of cross beef cattle in finishing phase; development of Marchangus: five years; and, bovine growth efficiency. In vegetable production area are addressed matters relating on management and olive cultivation, species of great economic importance and diversification as alternative on the property; functional foods in fruit and vegetables; influence of environmental factors, harvesting and drying in the production and composition of essential oils of Mentha spp; and, implication of the contamination of corn grain by mycotoxins in livestock production. At the end of the book, the expectation of the authors is to have contributed with relevant themes of Brazilian agriculture, which could reflect positively on knowledge, values and quality of available material.

Assessment and improvement of biotransfer models to cow’s milk and beef used in exposure assessment tools for organic pollutants

The aim of this study was to assess and improve the accuracy of biotransfer models for the organic pollutants (PCBs, PCDD/Fs, PBDEs, PFCAs, and pesticides) into cow’s milk and beef used in human exposure assessment. Metabolic rate in cattle is known as a key parameter for this biotransfer, however few experimental data and no simulation methods are currently available. In this research, metabolic rate was estimated using existing QSAR biodegradation models of microorganisms (BioWIN) and fish (EPI-HL and IFS-HL). This simulated metabolic rate was then incorporated into the mechanistic cattle biotransfer models (RAIDAR, ACC-HUMAN, OMEGA, and CKow). The goodness of fit tests showed that RAIDAR, ACC-HUMAN, OMEGA model performances were significantly improved using either of the QSARs when comparing the new model outputs to observed data. The CKow model is the only one that separates the processes in the gut and liver. This model showed the lowest residual error of all the models tested when the BioWIN model was used to represent the ruminant metabolic process in the gut and the two fish QSARs were used to represent the metabolic process in the liver. Our testing included EUSES and CalTOX which are KOW-regression models that are widely used in regulatory assessment. New regressions based on the simulated rate of the two metabolic processes are also proposed as an alternative to KOW-regression models for a screening risk assessment. The modified CKow model is more physiologically realistic, but has equivalent usability to existing KOW-regression models for estimating cattle biotransfer of organic pollutants.

Genetic analysis of average annual productivity of Nellore breeding cows (COWPROD)

With the aim of estimating the coefficient of heritability of average annual productivity of Nellore cows (COWPROD), a data set from 24,855 animals with known pedigree was analyzed. COWPROD is defined as the amount (in kilograms) of weaned calves produced yearly by one cow during her remaining time in herd ignoring a fixed period of 365 days. COWPROD was calculated regarding three standards: a) based on the post-weaning weight from the calves ignoring any kind of adjustment (COWPROD_NAJ), b) adjusted weight for the fixed effects (COWPROD_AJFIX) and c) adjusted weight for the fixed effects and for the genetic merit of the sire (COWPROD_AJFIN). The obtained heritabilities were 0.15, 0.15 and 0.16 for COWPROD_NAJ, COWPROD_AJFIX and COWPROD_AJFIN, respectively. A complete set composed of 105,158 COWPROD records on 130,740 animals in pedigree was also analyzed for predicting the genetic merit of all animals in the data set and for the calculation of the genetic, phenotypic and residual trends. Ranking correlation was high for the adjusted and non-adjusted data, yet, for some of the animals, the difference among the genetic values was large. This would be an indication that it would be better to work always with the adjusted weaning weights. The genetic trend was positive, but was of small magnitude (0.26% of the trait average) and the residual trend was negative as a consequence of the large intensification of the production system, which has been occurring in the last years in the farms studied. The phenotypic trend was also negative and intermediate between the genetic and the residual ones.