Feed Efficiency and Physiological Parameters of Holstein and Crossbred Holstein × Simmental Cows.

This study aimed to compare the feed efficiency (FE) and physiological parameters of Holstein and crossbred Holstein × Simmental cows in a confinement system during winter and summer. The study was conducted in a dairy farm in southern Brazil by including a total of 48 multiparous cows. The cows were studied for 21 days in two periods, summer and winter, and their daily dry matter intake (DMI), milk yield (MY), rectal temperature (RT), respiratory rate (RR), body weight, and body condition score were recorded. An analysis of variance was conducted using the SAS statistical package. The results showed that crossbred Holstein × Simmental cows have a similar FE as Holstein cows in a high-production system (1.83 × 1.81 kg DMI/kg MY, respectively), and they can achieve the same production levels as purebred Holstein cows (43.8 vs. 44.5 milk/cow/day). Our findings indicated a difference for the period as both genetic groups achieved higher FE in winter than in summer (1.98 vs. 1.67 DMI/kg MY, respectively). In addition, we found evidence that crossbred cows are better at dissipating body heat during heat-stress situations, as they have higher RR in summer compared to purebred cows, while Holstein cows have higher RT in summer afternoons than crossbred cows. Therefore, using crossbred Holstein × Simmental cows is an alternative for high-production systems.

Energy Balance Indicators during the Transition Period and Early Lactation of Purebred Holstein and Simmental Cows and Their Crosses.

Crossbreeding in dairy cattle has been used to improve functional traits, milk composition, and efficiency of Holstein herds. The objective of the study was to compare indicators of the metabolic energy balance, nonesterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), glucose, body condition score (BCS) back fat thickness (BFT), as well as milk yield and milk composition of Holstein and Simmental cows, and their crosses from the prepartum period until the 100th day of lactation at the Livestock Center of the Ludwig Maximilians University (Munich, Germany). In total, 164 cows formed five genetic groups according to their theoretic proportion of Holstein and Simmental genes as follows: Holstein (100% Holstein; n = 9), R1-Hol (51-99% Holstein; n = 30), first generation (F1) crossbreds (50% Holstein, 50% Simmental; n = 17), R1-Sim (1-49% Holstein; n = 81) and Simmental (100% Simmental; n = 27). The study took place between April 2018 and August 2019. BCS, BFT blood parameters, such as BHBA, glucose, and NEFA were recorded weekly. A mixed model analysis with fixed effects breed, week (relative to calving), the interaction of breed and week, parity, calving year, calving season, milking season, and the repeated measure effect of cow was used. BCS increased with the Simmental proportion. All genetic groups lost BCS and BFT after calving. Simmental cows showed lower NEFA values. BHBA and glucose did not differ among genetic groups, but they differed depending on the week relative to calving. Simmental and R1-Sim cows showed a smaller effect than the other genetic groups regarding changes in body weight, BCS, or back fat thickness after a period of a negative energy balance after calving. There was no significant difference for milk yield among genetic groups, although Simmental cows showed a lower milk yield after the third week after calving. Generally, Simmental and R1-Simmental cows seemed to deal better with a negative energy balance after calving than purebred Holstein and the other crossbred lines. Based on a positive heterosis effect of 10.06% for energy corrected milk (ECM), the F1, however, was the most efficient crossbred line.

Cattle rabies: the effect of clinical evolution, viral genetic lineage, and viral load on the severity of histological lesions / Raiva bovina: relação do curso clínico, da linhagem genética do vírus e carga viral com a intensidade de lesões histológicas

Our objective was the characterization and staging of histological lesions in different anatomical sites of the central nervous system (CNS) of rabid cattle. The severity of the lesions was compared with the clinical stages of the disease, the variants of viral isolates, and with the load of virus. Thirty-one spontaneously affected rabid cattle the state of Santa Catarina underwent clinical follow-up and were eventually necropsied. CNS tissues were sampled and submitted to direct fluorescent antibody technique (DFAT), immunohistochemistry (IHC), routine histopathology with hematoxylin and eosin stain (HE), reverse transcriptase polymerase chain reaction (RT-PCR), and polymerase chain reaction in quantitative reverse transcriptase in real time (qRT-PCR). Affected cattle were allotted in four groups according to their clinical stage when euthanized: G1, euthanized while standing; G2, euthanized when in sternal recumbence; G3, euthanized when in lateral recumbence; and G4, affected cattle with natural death. In order to evaluate the degree of severity of the lesions and the presence of Negri bodies (NBs), the brain was sectioned at 9 sites. Additionally, spinal cord and trigeminal ganglion sections were examined. The intensity of the lesions was graded as either absent, mild, moderate, or marked, and the presence or absence of the NBs was noted. Histological lesions were characterized by lymphocytic and monocytic meningoencephalitis with NBs in 28 cases. In all analyzed groups, intensities of histological lesions ranging from mild to severe were observed. Brain regions with the highest inflammatory lesion intensity were the medulla at the level of obex, followed by the colliculus and thalamus. NBs were observed in a higher percentage in the cerebellum, followed by medulla at the obex level, striatum complex, and frontal telencephalon. The duration of the clinical course of the disease did not influence the intensity of the inflammatory lesion, but it did influence the presence of NBs, with a higher percentage of these inclusions in cattle that died naturally than in euthanized cattle. All isolated rhabdovirus included in this study were genetically compatible with samples from hematophagous bats Desmodus rotundus. The evaluation by qRT-PCR did not demonstrate a correlation between lesion intensity and the amount of virus.(AU)

Nosso objetivo foi a caracterização e estadiamento de lesões histológicas em diferentes locais anatômicos do sistema nervoso central (SNC) de bovinos raivosos. A gravidade das lesões foi comparada com os estágios clínicos da doença, as variantes dos isolados virais e com a quantidade de vírus. Trinta e um bovinos do estado de Santa Catarina, afetados naturalmente por raiva, foram acompanhados clinicalmente e, ao final, necropsiados. Os tecidos do SNC foram amostrados e submetidos a imunofluorescência direta, imunohistoquímica, histopatologia de rotina, reação em cadeia da polimerase via transcriptase reversa (RT-PCR) e reação em cadeia da polimerase em transcriptase reversa quantitativa em tempo real (qRT-PCR). Os bovinos afetados foram distribuídos em quatro grupos, de acordo com sua fase clínica: G1, eutanasiados quando ainda se mantinham em pé; G2, eutanasiados quando em decúbito esternal; G3, eutanasiados quando em decúbito lateral; e G4, bovinos afetados com morte natural. Para avaliar o grau de gravidade das lesões e a presença de corpúsculos de Negri (CNs), o cérebro foi seccionado em 9 locais. Além disso, seções da medula espinhal e do gânglio trigêmeo foram examinadas. A intensidade das lesões foi graduada como ausente, leve, moderada ou acentuada, e a presença ou ausência dos CNs foi anotada. Lesões histológicas foram caracterizadas por meningoencefalite linfocítica e monocítica com CNs em 28 casos. Em todos os grupos analisados foram observadas intensidades de lesões histológicas variando de leve a grave. As regiões cerebrais com maior intensidade de lesão inflamatória foram o bulbo no nível do obex, seguido do colículo e tálamo. CNs foram mais prevalentes no cerebelo, seguido pelo bulbo ao nível do óbex, corpo estriado e telencéfalo frontal. A duração do curso clínico da raiva não influenciou a intensidade da lesão inflamatória, mas influenciou a presença de CNs, com maior porcentagem dessas inclusões em bovinos que morreram naturalmente do que em bovinos sacrificados. Todos os isolados rabdovírus obtidos neste estudo eram geneticamente compatíveis com amostras provenientes de morcegos hematófagos Desmodus rotundus.(AU)

Dietary roughage sources affect lactating Holstein x Zebu cows under experimental conditions in Brazil: a meta-analysis.

To reduce costs, lactating cows are often fed a higher proportion of roughage and alternative feeds; however, such protocols may not lead to optimal milk production. Using a meta-analysis, we evaluated the effects of dietary roughage sources on the composition, voluntary intake, and digestibility of diets fed to crossbred Holstein x Zebu cows under experimental feeding conditions in Brazil. Finally, we assessed the effects of dietary roughage sources on milk yield and composition. The database was composed of 43 experiments with 183 treatments, including 943 lactating cows. The data were obtained from studies published between January 2000 and December 2015. The data were evaluated by analysis of variance, considering the distribution of variables. The diets differed in dry matter and crude protein (CP) contents according to the roughage sources. Diets based on corn silage demonstrated higher intakes of neutral detergent fiber (NDF), CP, and total digestible nutrients, which improved the digestibility of NDF and CP, and resulted in a higher milk yield compared to the diets with one roughage source or those with a combination of two roughage sources. The present study demonstrated that feeding crossbred Holstein x Zebu lactating cows alternative roughage sources compromised milk production and that lactating cows produced higher milk yields when fed corn silage.

Reproductive and productive performance, udder health, and conformation traits of purebred Holstein, F1, and R1 crossbred Holstein × Simmental cows.

The objective of this study was to compare the reproductive performance, milk yield and composition, and udder health and conformation traits of Holstein (Ho), F1, and R1 crossbred Ho × Simmental (Sim) cows. Three commercial dairy farms in south Brazil were used as the research units. All farms held Ho, F1, and R1 crossbred Ho × Sim (¾ Ho × » Sim and ¾ Sim × » Ho) cows. The collection of milk samples and evaluation of udder conformation traits occurred during four visits to each farm. In addition to the actively collected data, retrospective reproduction records of the farms served as the basis for the statistical analysis using analysis of variance models using SAS. The F1 crossbred Ho × Sim cows and ¾ Sim (first rotational crossbreeding generation = R1 using Sim semen) cows had a shorter calving interval and calving to first service interval compared to the Ho cows (P < 0.0001). Milk yield did not differ among the genetic groups except for R1 (¾ Sim) that produced approximately 10% less milk than the other groups (P = 0.0245). Fat plus protein yield and somatic cell score did not differ among the genetic groups. Ho cows had shallower udders (P < 0.0001) and a higher udder clearance (P < 0.0001) than the other groups. F1 and R1 crossbred Ho × Sim cows had shorter reproduction intervals than purebred Ho cows. Although udder conformation traits lacked high-quality scores in crossbred cows, somatic cell scores reached the same level as in purebred Ho cows.

Risk factors related to seropositivity for Leptospira spp. in horses in the Serra Catarinense region / Fatores de risco relacionados a soropositividade para Leptospira spp. em equinos na região da Serra Catarinense

ABSTRACT: Leptospirosis is a zoonotic infectious disease caused by the bacterium Leptospira spp. The consequences of infection in horses are unclear, and the serogroups involved vary depending on the region. This study aimed to evaluate the seropositivity of unvaccinated horses in the Serra Catarinense region and the possible risk factors associated with the infection. We used 207 horses from 26 properties, with no clinical history of infection and unvaccinated for leptospirosis. We submitted serum samples to the microscopic agglutination serum (SAM) to obtain the main reference serogroups. We considered animals with titre ≥100 as infected. The results of the serology revealed seropositivity in 45.4% (94/207) of the animals studied. The most frequent antibodies reportedwere those against the serogroups Australis 16.9% (35/207), Ichterhaemorrhagiae 14.4% (30/207), and Grippotyphosa 5.31% (11/207). Among the primary risk factors associated with the infection we reported extensive rearing system (OR = 1.27; P<0.05) and the presence of other animal species such as cattle (OR = 3.85; P<0.01) and capybaras (OR = 2.07; P=0.06). The findings presented in this study showed that leptospirosis is endemic in horses in the Serra Catarinense region, and revealed the need for emergency surveillance and control measures specific to this important zoonosis.

RESUMO: A leptospirose é uma doença infecciosa zoonótica, causada pela bactéria Leptospira spp. Em equinos, as consequências da infecção não são claras e os sorogrupos envolvidos variam dependendo da região. Sendo assim, este trabalho objetivou avaliar a soropositividade de Leptospira spp. em equinos não vacinados na região serrana Catarinense e estimar os possíveis fatores de risco associados à infecção. Para tal, foram estudados 207 equinos, de 26 propriedades, sem histórico clínico da infecção e não vacinados para leptospirose. As amostras de soro foram submetidas ao ensaio de soro aglutinação microscópica (SAM) para os principais sorogrupos de referência. Animais com título ≥100 foram considerados reagentes. Os resultados da sorologia revelaram uma soropositividade de 45,4% (94/207) para os animais estudados. Com maior frequência foram observados anticorpos contra os sorogrupos Australis 16,9% (35/207), Icterohaemorrhagiae 14,4% (30/207), e Grippotyphosa 5,31% (11/207). Dentre os principais fatores de risco associados à infecção observados, foram o sistema de criação extensivo (OR=1,27; P<0,05) e a presença de outras espécies animais como bovinos (OR=3,85; P<0,01) e capivaras (OR=2,07; P=0,06). Os achados apresentados neste estudo mostraram que a leptospirose em equinos é endêmica na região da serra Catarinense, e revelam a necessidade de medidas emergenciais de vigilância e controle específicas para esta importante zoonose.

Reproductive performance and survival of Holstein and Holstein × Simmental crossbred cows.

Crossbreed dairy breeds, such as Holstein × dairy type of Simmental, have been generally used to improve fertility, udder health, and longevity of dairy herds. The aim was to compare the reproductive performance and survival of Holstein and Holstein × Simmental crossbred cows. Data from two farms were used as follows: one located in Bom Retiro, in the state of Santa Catarina, Brazil. and another in Carambeí, Paraná state. Information concerning birth, inseminations, and parity date were obtained from the management software of the farms, generating information regarding the calving interval, days between calving to first service, conception rate, and age at first calving. At one of the farms, calving was monitoring to quantify dystocia. Live weight as well as body condition score (BCS) of cows and information of culling were obtained to determine the survival rate. Data were analyzed by variance analysis and by logistic regression. Crossbred Holstein × Simmental cows had better reproductive performance than the Holstein cows, characterized by lower calving interval (381 vs. 445 days), higher conception rate (37.3 vs. 33.6 %), and shorter calving to first service interval (65 vs. 89 days). These results were related to a higher BCS in crossbred cows (3.63 vs. 2.94 points). Crossbred Holstein × Simmental cows had higher survival rate than Holstein cows on the second parity (83 vs. 92 %). No differences between genetic groups were observed (P > 0.05) for body weight and dystocia. In conclusion, Holstein × Simmental crossbred cows have better reproductive performance and higher survival rate than Holstein cows.

Milk traits of lactating cows submitted to feed restriction.

Data from five experiments with dairy cows where feed was restricted to 0, 40, and 50% of the ad libitum amount, with 259 observations, were subjected to multivariate analyses to determine the effects of severity and duration of feed restriction on production, physical-chemical characteristics, ethanol stability, and somatic cell score of milk. A negative relationship was seen between the severity and duration of feed restriction with milk production, lactose content, titratable acidity, and milk stability to the ethanol test. The milk stability to the ethanol test, protein content, milk yield, and somatic cells score were the most important attributes retained by the discriminant analysis. Milk stability to the ethanol test, live weight, days in restriction, and pH were the most important characteristics explaining the variance within the different levels of feed restriction. Milk production and ethanol stability were significantly lower in both levels of feed restriction compared with the group fed ad libitum. When feed restriction was followed by refeeding, the difference observed in ethanol stability was the first discriminant variable, followed by the difference in unstable milk frequency and titratable acidity. Increments in the severity and duration of feed restriction negatively affect milk production and milk ethanol stability.

Qualidade do leite e a sua relação com o sistema de produção e a estrutura para ordenha / Milk quality and its relation with the production system and the structure for milking

O trabalho objetivou relacionar aspectos da produção leiteira e estrutura para ordenha com a qualidade do leite da região do Vale do Braço do Norte ­ SC, utilizando técnicas de análise multivariada. O estudo foi realizado em 20 propriedades leiteiras, fornecedoras de uma indústria de laticínios, selecionadas aleatoriamente nos municípios da região. As informações sobre o sistema de produção foram obtidas através do preenchimento de uma lista de verificação durante a ordenha. Os dados de produção, composição, Contagem de Células Somáticas (CCS) e Contagem Bacteriana Total (CBT) foram disponibilizados pela indústria, sendo utilizada a média dos valores dos últimos três meses. Os dados foram avaliados através de análise multivariada (análise fatorial e análise de correspondência múltipla), utilizando-se o pacote estatístico SAS®. Observou-se relação positiva entre a CCS e a CBT, e entre os teores de gordura e proteína do leite, sendo que as contagens são antagônicas aos teores. A produção de leite por propriedade e a produtividade das vacas também se relacionaram positivamente. As propriedades com maiores valores destas variáveis possuíam ordenha canalizada, sala de ordenha com bom arejamento, fosso azulejado, contenções de metal e alimentavam os animais após a ordenha. As propriedades com menores valores possuíam ordenha balde ao pé, sala de ordenha mal arejada, com fosso concretado, contenções de madeira e faziam a alimentação durante a ordenha. No entanto, a CCS e a CBT não se relacionaram com nenhum destes componentes, constatando que tecnologias e estrutura física não são garantia de uma melhor qualidade do leite.

This study aimed to relate aspects of milk production and structure for milking with the milk quality in the region of Vale do Braço do Norte in Santa Catarina, using multivariate analysis techniques. The study was conducted on 20 dairy farms that sell milk to a dairy industry, randomly selected in the region. Information about the production system were obtained from completion of a checklist during milking. Production data, composition, somatic cell count (SCC) and Total Bacterial Count (TBC) were provided by the industry, using mean values from the last three months. Data were analyzed by multivariate analysis (factorial analysis and multiple correspondence analysis), using the SAS ® statistical package. There was a positive relation between SCC and TBC, and between fat and protein contents, and that counts are antagonistic to contents. Milk production per farm and cow productivity also correlated positively. Farms with higher values of these variables had channeled milking, milking room with good airing, tiled moat, contention made metal and they fed the animals after milking. Farms with lower values had to bucket-type milker, milking room badly aired, concreted moat, contention made wood and they fed the animals during milking. However, SCC and TBC were not related to neither of these components, stating that technology and physical structure are not a guarantee of a better milk quality.

Qualidade da água de granjas de postura comercial da região Sul de Santa Catarina em relação ao Ofício Circular Conjunto DFIP/DSA nº 1/2008 / Water quality of commercial laying hen farms in the southern region of Santa Catarina regarding the report DFIP/DSA 1/2008

O objetivo deste trabalho foi avaliar a qualidade da água de granjas de postura comercial da região Sul de Santa Catarina e contextualizá-la com o Ofício Circular Conjunto DFIP/DSA nº 1/2008. Em fevereiro de 2012 foram coletadas amostras de água de 31 granjas localizadas nos municípios de São Ludgero, Orleans, Grão Pará e Braço Norte. Os parâmetros químicos e microbiológicos avaliados foram os estabelecidos no anexo II do Oficio Circular Conjunto DFIP/DSA nº 1/2008. Sendo assim foram analisados cloreto, dureza, nitrato, sulfato, pH e sólidos dissolvidos totais (SDT) e Escherichia coli no que se refere à análise bacteriológica. Quantificou-se a adequação das amostras em relação ao Ofício Circular Conjunto DFIP/DSA nº 1/2008 e avaliou-se a qualidade da água de acordo com o tipo de fonte e número de aves em produção por meio da análise de variância. Os resultados indicaram que as águas apresentaram adequação para SDT, cloreto e sulfato. Foi encontrada inadequação nos parâmetros: pH (em 26% das amostras), dureza (6,5%), nitrato (54,8%) e presença de Escherichia coli (46,2%). As análises de acordo com o número de aves e tipo de fonte não apresentaram diferença estatística significativa (p > 0,05). Observaram-se que 93,5% das amostras não se enquadraram em pelo menos um parâmetro. Concluíram-se que as águas das granjas da Região Sul de SC não estão totalmente de acordo com o Ofício Circular Conjunto DFIP/DSA nº 1/2008, apresentando problemas no que se refere ao pH, dureza, nitrato e E. coli; a qualidade da água independe do número de aves em produção e do tipo de fonte que abastece a granja.(AU)

The aim of this study was to evaluate the water quality of laying hen farms in the South of Santa Catarina and contextualize them with the report DFIP/DSA 1/2008. Water samples were collected in February, 2012, from 31 farms located in the cities of São Ludgero, Orleans, Grão Para and Braço Norte. The chemical and microbiological parameters were set out in Attachment II, in the report DFIP/DSA 1/2008. Thus, the following were analyzed: chloride, hardness, nitrate, sulfate, pH and total dissolved solids (TDS) and Escherichia coli regarding the bacteriological analysis. The suitable samples were quantified for the report DFIP/DSA 1/2008 and water quality was evaluated according to the font type and number of birds in production by analysis of variance. The results indicated that water presented suitability to SDT, chloride and sulfate. Inadequacy was found in pH (in 26% of samples), hardness (6.5%), nitrate (54.8%) and the presence of Escherichia coli (46.2%). The analysis according to the number of birds and font type showed no statistically significant differences (p > 0.05). It was observed that 93.5% of the samples did not fit in at least one criterion. It is concluded that the waters from farms in the southern region of SC are not fully in accordance with the report DFIP/DSA 1/2008, presenting problems with regard to pH, hardness, nitrate and E. coli; the water quality is independent of the number of birds in production and type of source that supplies the farm.(AU)

Farelo de glúten de milho para vacas leiteiras em pastos de azevém anual / Corn gluten meal to dairy cows grazing italian ryegrass

Neste trabalho, foi avaliado o efeito da suplementação com proteína de baixa degradabilidade ruminal (PNDR) para vacas leiteiras em pastos de azevém anual (Lolium multiflorum Lam.). Foram utilizadas 12 vacas da raça Holandesa no terço médio de lactação. Os tratamentos avaliados foram zero e 4,0kg vaca-1 dia-1 de uma mistura 60:40 de grão de milho + farelo de glúten de milho, em três períodos de avaliação de 15 dias. Os animais foram distribuídos em quatro lotes uniformes (dois por tratamento) e alocados em piquetes de azevém manejado no método rotativo, com uma oferta de 24kg de MS vaca-1 dia-1. A massa de forragem (2.325kg MS ha-1) e a altura (15,8cm) antes da entrada dos animais foram semelhantes nos piquetes dos animais suplementados e não suplementados. Da mesma forma, os teores médios de PB e FDN da forragem ingerida foram semelhantes entre tratamentos (18,9% e 53,0%, respectivamente). O consumo de MS da forragem não variou com o uso da suplementação (média=8,5kg vaca-1 dia-1). O consumo de MS total aumentou 3,0kg vaca-1 dia-1 e o de energia metabolizável aumentou 42MJ vaca-1 dia-1. A produção de leite aumentou 4,0kg vaca-1 dia-1 com o uso da suplementação, mas os teores de gordura e de proteína não variaram entre tratamentos, sendo observados valores médios de 32,8g kg-1 e 29,2g kg-1, respectivamente. Em baixa oferta de forragem, a suplementação com alimento concentrado (22% PB) contendo farelo de glúten de milho eleva a produção de leite na ordem de 1kg por kg de concentrado. A resposta a esse tipo de suplementação em condição de oferta de forragem não-limitante deve ser estudada.

The aim of this research was to evaluate the effect of undegradable protein supplementation to dairy cows grazing Italian ryegrass. Twelve Holstein cows in the mid lactation were used and treatments were 0 (zero) and a mixture (60:40) of ground corn + corn gluten meal (4.0kg cow day-1) evaluated along three periods of fifteen days. Cows were distributed in four groups (two per treatment) and assigned to Italian ryegrass plots submitted to intermittent grazing with a herbage allowance of 24kg of DM cow day-1. Pre-grazing herbage mass (2325kg of DM ha-1) and sward surface height (15.8cm) were similar on plots and crude protein and NDF of ingested forage were 18.9 and 53,0%, respectively. Supplementation did not affect herbage DM intake (mean=8.5kg cow day-1) but, both, total DM intake and metabolisable energy increased 3.0kg and 42MJ cow day-1, respectively. Supplementation increased milk production (4.0 kg.cow.day-1) but did not change protein and fat milk content (32.8 and 29.2g kg-1). At low herbage allowance, supplementation with corn ground meal (22% of crude protein) increase milk production on proportion of 1:1 and studies should be done at conditions of non- limitant herbage allowance.

Vitrificação de oócitos e embriões bovinos produzidos in vitro e expostos à citocalasina B / Vitrification of oocytes and in vitro produced bovine embryos exposed to cytochalasin B

Foi avaliada a influência da citocalasina B na vitrificação de oócitos e embriões bovinos produzidos in vitro. No Experimento I, 956 oócitos foram maturados por 22h, sendo imediatamente vitrificados (tratamento Vitri) ou expostos por 15 a 20 minutos, à solução com 7,5µg/mL (tratamento CB7,5Vitri) ou 45µg/mL (tratamento CB45Vitri) de citocalasina B, antes da vitrificação. Após 30 segundos de exposição à SV1 [400µl TCM-Hepes com 10 (por cento) soro fetal (SF), 50µl etilenoglicol (EG) e 50µl DMSO], e 20 segundos à SV2 (300µl trealose 1,0M + 20 (por cento) SF, 100µl EG e 100µl DMSO), os oócitos foram vitrificados em palhetas estiradas (OPS). O reaquecimento foi realizado a 37-38ºC em duas etapas de 5 minutos cada, em trealose 0,3M e 0,15M. Não houve diferenças (P>0,05) nos percentuais de clivagem e desenvolvimento embrionário entre os tratamentos Vitri, Cito7,5Vitri e Cito45Vitri, os quais foram inferiores (P<0,05) ao controle. No Experimento II, 269 blastocistos expandidos foram distribuídos em 3 tratamentos. No tratamento Vitri, os embriões foram expostos por 1 minuto à SV1 e 20 segundos à SV2, a qual foi modificada pela substituição da trealose por TCM-Hepes. No tratamento CB45Vitri, a vitrificação ocorreu após exposição de 10 minutos à solução com 45µg/mL de citocalasina B. Não foram observadas diferenças (P>0,05) no percentual de re-expansão e eclosão entre os grupos Vitri e CB45Vitri, os quais foram inferiores (P<0,05) ao grupo controle. Os resultados indicam que, independentemente da dose utilizada, a exposição a citocalasina B não produz efeito benéfico na vitrificação de oócitos ou blastocistos bovinos produzidos in vitro

Fatores que afetam a produção de leite e o período de lactação em um rebanho das raças Flamenga e Holandesa no Planalto Catarinense / Factors affecting milk yield and lactation period in a Flemish and Holstein herd in upland of Santa Catarina State - Brazil

Estudaram-se dados referentes à produção de leite em até 305 dias de lactação e ao período de lactação em 217 lactações de 104 vacas das raças Flamenga e Holandesa, oriundas do rebanho da Estação Experimental de Lages, pertencente à Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina (EPAGRI). As médias e erros-padrão da produção de leite em até 305 dias de lactação e seus respectivos coeficientes de variação foram 4.179,48 ± 89,65kg e 22,33% e, 205,17 ±4,91 dias e 15,16%, respectivamente. O desempenho da raça Flamenga foi inferior à raça Holandesa em 24,5% para produção de leite (4763 vs. 395 9kg) e em 8% para duração da lactação (317,9 vs. 292,4 dias). A estação de parto afetou somente o período de lactação, sendo as lactações iniciadas no verão mais longas que as iniciadas na primavera. A idade da vaca ao parto influenciou quadraticamente a produção de leite, sendo a idade de 69 e 96 meses a de máxima produção para as raças Holandesa e Flamenga, respectivamente. O ano de parto não afetou as características estudadas.

Data on milk yield in 305 days of lactation and lactation period of 217 lactations of 104 Flemish and Holstein cows from the Experimental Station of Lages, Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina (EPAGRI) were analysed. Means, standard errors and coefficients of variation from milk yield in 305 days of lactation and lactation period were 4.179.48 ± 89.65kg and 22.33% and. 305.17 ± 4.91 days and 15.16%, respectively. Performances of the Flemish cows were poorer than the Holstein cows in 24.5% for milk yield ( 4763 vs. 3959kg) and in 8% for lactation period (317.9 vs. 292.4 days). Calving season affected only the lactation period. Lactations started in summer were longer than those started in spring. Calving age showed a quadratic effect on milk yield. The age of the top production were 69 and 96 months for Holstein and Flemish cows. Year of parturition did not affect milk yield and lactation period.