Bruna da Rosa Curcio

Vitrification of the inner perivitelline layer of chicken eggs for use in the sperm-egg interaction assay

The sperm-egg interaction assay is a good predictor of the fertilizing potential of rooster semen; the ability of chicken sperm to interact with the egg can be assessed by counting the number of holes in the inner perivitelline layer (IPVL) of a freshly laid egg. Although isolated IPVL can be stored for up to 24h, preservation of IPVL for prolonged intervals in liquid nitrogen would facilitate the sperm-egg interaction assay. The objective of this study was to adapt the technique of vitrifying swine oocytes for use with the IPVL. Our hypothesis was that vitrification would not alter the ability of the membrane to bind sperm; therefore, there would be no difference between vitrified and fresh IVPL in the number of hydrolysis holes made by sperm. Our hypothesis was supported; there were no differences in the mean+/-SEM number of holes made by the same sample of sperm in vitrified and in fresh membranes (146.0+/-17.7 holes/mm(2) IPVL and 159.5+/-17.7 holes/mm(2) IPVL, respectively, P>0.05; n=123 IVPLs tested). Furthermore, 80% of frozen-thawed membranes were recovered intact. Because vitrification did not significantly change the ability of membranes to bind sperm, vitrified membranes can be safely used for the sperm-egg interaction assay. Vitrified IVPL would ensure availability for sperm evaluation and facilitate wide distribution of IPVL, enabling assays to be conducted even in the absence of facilities or expertise to prepare membranes.

Effect of urine contamination on stallion semen freezing ability

Urospermia is a common ejaculatory dysfunction of stallions. Current practice suggests that urine contaminated semen should not be used for cryopreservation. The aim of this study was to determine effects of urine contamination on semen freezing. Sixty-five ejaculates from eight stallions were divided into no urine (CONT), low (20% urine, LOW), and high (50% urine, HIGH) samples. Semen was extended with a commercial cooling extender, cushion-centrifuged, resuspended to 200 million/mL in a commercial egg-yolk based extender, and cryopreserved in liquid nitrogen. A subset of ejaculates (n = 20) were split in two after cushion-centrifugation, and one half of the ejaculate was submitted to a single-layer gradient centrifugation before cryopreservation. Sperm motility parameters were assessed pre- and post-freezing with an automated sperm analyzer. Semen pH, creatinine, and urea concentrations were assessed in raw samples, after urine contamination and after centrifugation and extension. Statistical analyses were performed with ANOVA and Tukeys posthoc. There were significant reductions in total and progressive sperm motilities (i.e., %TM and %PM, respectively) with increasing urine contamination pre-freezing (%TM 67 ± 1.7, %PM 50 ± 2.2, CONT), (%TM 60.3 ± 1.7, % PM 42.5 ± 2.1, LOW), and (%TM 41.3 ± 2, %PM 21.3 ± 1.5, HIGH). Post-thaw motilities for CONT (%TM 54 ± 2.3, %PM 40.8 ± 3.3) and LOW (%TM 51.7 ± 1.8, %PM 36.2 ± 2.1) were not different, but were higher than the HIGH (%TM 31.5 ± 1.2, %PM 17.1 ± 1.0) (p < 0.05). Post-thaw sperm viability was significantly lower in the HIGH (54.7 ± 2.4) than in the CONT (63.8 ± 2.3) or LOW (64.6 ± 3.4) groups. Semen creatinine and urine levels were significantly higher with increasing urine contamination and were significantly decreased after centrifugation and resuspension in freezing extender. Pre-treatment semen pH was significantly lower than semen contaminated with low or high amounts of urine, and pH decreased significantly after centrifugation and resuspension. Gradient centrifugation did not improve %TM in the control group, but it did improve pre-freeze %TM and %PM in the low and high groups and improved significantly post freezing %TM and %PM in the high urine contaminated group. Semen contaminated with a small amount of urine may be suitable for freezing, whereas highly contaminated semen might not be usable. Although urine was mostly removed in this fashion, the initial exposure to high quantities was sufficient to decrease sperm motility pre- and post-freezing, whereas low urine contamination was not as detrimental.

ESTRESSE OXIDATIVO NA GESTAÇÃO: QUAL A PERCEPÇÃO NA ESPÉCIE EQUINA? - REVISÃO

Esta revisao buscou evidencias da manifestacao de estresse oxidativo na gestacao de equinos e consequencias no periodo neonatal. Alteracoes na perfusao placentaria na egua podem ocorrer em estagios tardios de desenvolvimento fetal, resultando em potros com baixo peso ao nascimento ou graus variaveis de imaturidade. Em humanos, o estresse oxidativo esta envolvido em situacoes de hipoxia nas gestacoes de risco, como pre-eclâmpsia, hipertensao induzida pela gestacao ou diabetes mellitus . O aporte de oxigenio durante a gestacao e bastante elevado, podendo cursar com a producao de especies reativas de oxigenio, alem de falha dos mecanismos de protecao antioxidante, o que causa o dano oxidativo. Existem muitas descricoes sobre o papel do estresse oxidativo na gestacao em humanos e sua relacao direta com alteracoes fetais e neonatais, sendo que no equino este processo ainda nao esta estabelecido. Eguas gestantes com laminite cronica apresentam sindrome hipertensiva, causando a producao de placentas mais leves e reducao da luz vascular, semelhante aos achados observados na placenta de mulheres com hipertensao. Os radicais livres tem sido relacionados com a patogenia da sepse neonatal, baixo peso ao nascer e encefalopatia neonatal em humanos. Estudos em potros demonstraram reducao dos mecanismos antioxidantes nos neonatos severamente acometidos clinicamente, mas nao revelaram indicios de dano oxidativo instalado. Esta revisao evidenciou que a egua pode apresentar achados de insuficiencia placentaria tardios, semelhante aos encontrados em mulheres com pre-eclâmpsia, sendo que essas alteracoes podem estar relacionadas a manifestacoes de estresse oxidativo durante a gestacao.

Planejamento e gestão de custos: estudo de caso de uma empresa do segmento agropecuário

Objetivando estabelecer indicadores para planejamento e tomada de decisao futura, o presente trabalho realizou uma avaliacao do custo operacional efetivo de uma empresa rural. Foram analisados: gastos com renovacao e recuperacao de pastagens, nutricao, mao de obra e manejo sanitario de uma empresa agropecuaria. Nao foi verificada diferenca significativa entre os valores medios dos anos avaliados. Foram aferidas as contribuicoes dos itens supracitados, para a formacao do custo operacional efetivo (COE) total. Estas contribuicoes mantiveram-se estaveis, podendo ser utilizadas como indicadores em planejamentos de custos futuros. As contribuicoes das componentes, para formacao do COE total, estao relacionadas com o tamanho do plantel e com os padroes de qualidade estabelecidos para a criacao. Ferramentas como controle de receitas e despesas, planejamento de custos e analise de resultados sao recursos que, adequadamente adaptados as especificidades do setor, qualificam a capacidade administrativa do negocio e consequentemente a busca por gerenciamento eficiente e sustentavel.