ABSTRACT The objective was to evaluate the inclusion of chitosan (CHI) and technical cashew nut shell liquid (CNSLt) as natural feed additives in cattle diets on nutrient digestibility, ruminal fermentation, and in vitro gas production kinetics. We conducted a completely randomized design with 5×4 factorial arrangement, with 20, 35, 50, 65, and 100% Tifton 85 hay and four additives, monensin (200 mg/kg DM), CNSLt (500 mg/kg DM), CHI (500 mg/kg DM), and CNSLt+CHI (500 mg/kg DM/each). Dry matter (DM) and organic matter (OM) digestibility showed a linear reduction according to forage levels. The highest DM digestibility was observed with CHI on cattle diets. Inclusion of CHI increased DM digestibility. The highest in vitro organic matter and crude protein (CP) digestibilities were observed for CNSLt+CHI. The in vitro dry matter digestibility increased linearly with concentrate in the diet. There was interaction of forage:concentrate ratio and the additives for neutral detergent fiber, acid detergent fiber and hemicellulose digestibility. Chitosan, CNSLt, and CNSLt+CHI promoted the lowest acetate:propionate ratio compared with monensin. Total gas production showed interaction of the forage:concentrate ratio and additives. Lag time was lowest with CNSLt+CHI. Chitosan and CNSLt can be considered alternative fermentation modulators to ionophores by improving nutrient digestibility and increasing ruminal propionate concentrations.

Abstract Recent molecular tools and technologies have marked the discovery of the origin and domestication processes of a wide variety of species, using either genomic or mitochondrial molecular markers to provide input for selection programs, as well as the management and conservation of animal breeds. This study aimed to analyze genes of mitochondrial DNA of the following sheep (Ovis aries) breeds: Pantaneira, Bergamácia, Dorper, White Dorper, Ile de France and Hampshire Down, to obtain their population genetic parameters and investigate the origin of these sheep populations reared in the State of Mato Grosso do Sul. The analysis of mitochondrial DNA allowed to infer their phylogenetic relationships and revealed significant differences among them when compared with each other and with sequences obtained from GenBank. Through the formation of haplotypes, it was noted that the Pantaneira breed served as the maternal basis for the formation of the other breeds reared in the region, and it was possible to suggest a European origin for the sheep populations studied.

ABSTRACT The objective of this work was to study the behavior of swine females in the grower phase using different observation intervals (continuous, 5, and 10 min). A total of 42 swine were used, 14 of them for each treatment, which were identified with a marker stick. These animals were observed using the focal sampling method for 5 h. The treatments were the observation intervals: continuous, every 5 min, and every 10 min. Among the behaviors analyzed during the experiment, the different observation intervals did not affect the estimated time spent in the activities. Time observation intervals of 10 min or less adequately describe the duration of the main behavioral parameters of female pigs in this setting.

RESUMO Objetivou-se avaliar o efeito da inclusão de glicerina bruta (GB) em substituição ao milho, na dieta de cordeiros Pantaneiros confinados, sobre as características da carcaça e qualidade da paleta e do pernil. Foram utilizados 24 cordeiros machos, não castrados, em delineamento inteiramente casualizado, com quatro tratamentos (0, 2,5, 5,0 e 7,5% de GB em base da MS). Não houve efeito da inclusão de GB sobre os não componentes de carcaça. Houve efeito quadrático para peso de carcaça quente, com menor valor para 2,5% de GB. A composição regional e tecidual da carcaça não foi alterada pela substituição do milho pela GB. A composição tecidual da paleta e pernil e as características instrumentais da paleta não foram afetadas pelos teores de GB. Houve efeito quadrático para a intensidade de amarelo do pernil, com maior valor para 5,0% de GB. O teor de extrato etéreo da paleta apresentou efeito linear decrescente. Pode-se recomendar a utilização de 7,5% de GB, na matéria seca, em substituição ao milho, sem alteração das características da carcaça e qualidade da carne.

SUMMARY The objective was to assess the effect of inclusion of crude glycerin (CG) replacing corn in the diet of feedlot Pantaneiro lambs on the non-carcass components, regional and tissue composition, and carcass traits. Were used 24 not castrated males, in a completely randomized design with four treatments (0, 2.5, 5.0 and 7.5% of CG on DM basis). There was no effect of GB inclusion on non-carcass components. There was a quadratic effect for hot carcass weight, with lower value to 2.5% of CG. Regional and tissue composition of the carcass was not affected by the substitution of corn by CG. The tissue composition of shoulder and leg and instrumental traits of the shoulder were not affected by CG. There was a quadratic effect for the yellowness of the leg, with high value for 5.0% of GB. The ether extract content of shoulder showed decreased linear effect. The use of 7.5% of CG, in dry matter, can be recommend to replace corn of feedlot diets, without changing carcass traits and meat quality.

ABSTRACT This study assessed the use of conformation and fatness scores of the EUROP sheep carcass grading system to predict weight and percentage of salable meat from Brazilian market lambs. Data were collected from in vivo, carcass, and retail production from 252 uncastrated lambs. Evaluated models included single regressions, two multivariate models, and one determined by the stepwise procedure. Conformation was moderately correlated with weight of salable meat. Fatness scores were correlated with rump perimeter, carcass width, and thoracic depth with coefficients of −0.33, −0.32, and −0.23, respectively. Body weight was the best single predictor for weight of salable meat and cold carcass yield for percentage of salable meat. All multivariate models for weight of salable meat prediction were significant. Stepwise regression with body weight, leg perimeter, thoracic depth, rump perimeter, and fatness scores predicted 98% of weight of salable meat variation. For percentage of salable meat prediction, stepwise regression with cold carcass yield, leg perimeter, and conformation score was significant. The EUROP conformation and fatness scores can be used in Brazil for the prediction of lamb meat production.

RESUMO Objetivou-se avaliar o efeito da inclusão de níveis de glicerina bruta na alimentação de cordeiros nas características biométricas e histológicas testiculares. Foram utilizados 24 cordeiros não castrados, confinados com 93,79 ± 5,73 dias de idade e peso corporal de 20,22±2,84kg. Os tratamentos testados foram: 0; 2,5; 5,0 e 7,5% de inclusão de glicerina bruta na matéria seca da dieta em substituição ao milho. Os animais foram abatidos usando a condição corporal como critério em escore de 2,5 a 3,5, em uma escala que varia de 1 a 5, sendo que as variáveis avaliadas foram o peso inicial, peso final, peso de carcaça quente, espessura de gordura de cobertura, condição corporal, e os parâmetros biométricos testiculares: perímetro escrotal, peso testicular no escroto, peso dos testículos direito e esquerdo, volume dos testículos direito e esquerdo, largura testicular, comprimento testicular, diâmetro de túbulo seminífero e altura de epitélio germinativo. Não houve influência significativa dos níveis de glicerina bruta sobre nenhuma das variáveis analisadas, também não houve correlação entre as características avaliadas com a condição corporal. Foram observadas correlações positivas entre o peso de carcaça quente e espessura de gordura de cobertura (r=0,57, p<0,05). Houve correlação positiva (r=0,55, p<0,05)) entre perímetro escrotal e peso corporal. O diâmetro do túbulo (r=0,47, p<0,05) e a altura do epitélio seminíferos (r=0,62, p<0,05) estiveram correlacionados com o volume testicular. A inclusão de níveis crescentes de glicerina bruta na alimentação de cordeiros Pantaneiros até 7,5% de inclusão não influencia nas características biométricas e histométricas testiculares dos animais.

SUMMARY Objective to evaluate the effect of the inclusion of levels of crude Glycerin in the feeding of lambs in the biometric characteristics and testicular histological. 24 lambs were neutered, not confined with 93.79 ± 5.73 days of age and body weight of 20.22 ± 2.84 kg. The treatments tested were: 0; 2.5; 5.0 and 7.5% of crude Glycerin injection in dry matter of diet in place of maize. The animals were slaughtered using the criteria in body condition score of 2.5 to 3.5 on a scale ranging from 1 to 5, and the variables evaluated were the initial weight, final weight, hot carcass weight, fat cover thickness, body condition, and the biometric parameters: testicular weight, scrotal perimeter in the scrotum, testicle weight left and right volume of right and left testicle, testicular testicular length width, seminiferous tubule diameter and height of germinal epithelium. There was no significant influence of crude Glycerin levels on any of the variables analyzed, also there was no correlation between the features assessed with body condition. Positive correlations were observed between hot carcass weight and fat thickness (r=0,57, p= p<0,05)). There was positive correlation (r=0,55, p= p<0,05)) between scrotal perimeter and body weight. The tubule diameter (r=0,47, p=p<0,05) and height of the seminiferous epithelium (r=0,62, p=p<0,05) were correlated with testicular volume. The inclusion of increasing levels of crude Glycerin in the feeding of lambs Pantaneiros, did not influence the biometric characteristics and testicular histométrics of animals.

Estudos básicos sobre técnicas de extração de DNA são de extrema importância para o sucesso de trabalhos científicos no campo da biologia molecular. A extração e a purificação de ácidos nucleicos constituem etapas fundamentais para o estabelecimento de posteriores análises genéticas. Objetivou-se neste trabalho avaliar a eficácia de diferentes protocolos de extração de DNA por meio da determinação de quantidade, qualidade e a possibilidade de amplificação por meio de PCR do material genético extraído. Utilizou-se amostras de sangue de dez animais, que foram submetidas à extração de DNA e, logo após à reação em cadeia pela polimerase (PCR). Os resultados das análises obtidas por nanofotometria indicaram que a quantidade e a qualidade do DNA genômico foram consideradas satisfatórias, em todos os protocolos, para a realização da PCR, mas houve diferença estatística significativa entre os parâmetros analisados, tanto na quantidade quanto na qualidade (p < 0.05) do DNA obtido. O protocolo de extração utilizando sangue total foi mais eficiente quanto ao tempo e a qualidade do DNA extraído, entretanto em todos os processos de extração houve ausência de degradação. Também foi demonstrado a possibilidade de amplificação da região do exon 2 do gene da leptina de bovinos no DNA extraído.

Basic studies on DNA extraction techniques are very important for the success of scientific papers in the field of molecular biology. The extraction and purification of nucleic acids are critical steps for establishing further genetic analysis. The objective of this study was to evaluate the efficacy of different protocols for DNA extraction by determining the quantity and quality of extracted genetic material and the possibility of amplification by PCR. We did DNA extraction and PCR of ten bovine blood samples. The test results obtained by spectrophotometry indicated that the quantity and quality of genomic DNA were considered satisfactory in all protocols for PCR. However, there was a statistically significant difference between the parameters measured, both in quantity and in quality (p <0.01). The extraction protocol using whole blood was more efficient in terms of time and quality; there was no degradation in all processes of extraction. It was also demonstrated that the possibility of amplification of the region of exon 2 of the leptin gene in extracted DNA exists.

RESUMO A suinocultura resulta na produção de grandes quantidades de resíduos, os quais, quando manuseados incorretamente, podem causar graves problemas ambientais. Este estudo objetivou testar modelos matemáticos para estimar os parâmetros de biodigestão anaeróbia em biodigestores, em função da variação da composição de efluentes de suinocultura com e sem separação da fração sólida e dos tempos de retenção hidráulica (TRH). Foram utilizados biodigestores semicontínuos, abastecidos com efluentes de suinocultura com e sem separação da fração sólida, manejados por 15, 22, 29 e 36 dias de retenção hidráulica. Foram avaliados os potenciais de produção de biogás e metano e as reduções de sólidos totais, sólidos voláteis e demandas químicas de oxigênio, em função da composição dos efluentes. O TRH foi a variável que teve maior influência na variação dos modelos, seguido dos teores de sólidos totais e voláteis. Os modelos uni e multivariados apresentaram elevados índices de confiança, sendo classificados como ótimos para predizer os potenciais de produção de biogás e metano e como bons para predizer as reduções de sólidos totais, sólidos voláteis e demanda química de oxigênio. Os modelos deste estudo podem ser utilizados para predizer com segurança os parâmetros do processo de biodigestão anaeróbia de efluentes de suinocultura, em biodigestores semicontínuos tubulares.

ABSTRACT Pig breeding results in the production of large amounts of waste, which can cause serious environmental problems, when handled incorrectly. This study aimed at testing mathematical models to estimate the parameters of anaerobic biodigestion in biodigesters as a function of the composition of swine effluents with and without separation of the solid fraction and hydraulic retention times (HRT). Semi-continuous biodigesters fed with swine effluents with and without separation of the solid fraction and managed for 15, 22, 29 and 36 days of hydraulic retention were used. The potential of biogas and methane production, as well as the reduction of total solids, volatile solids and chemical oxygen demand, were assessed as a function of the effluents composition. HRT was the variable that most influenced the variation of the models, followed by the contents of total and volatile solids. Uni and multivariate models presented high confidence indices, being classified as “great” at predicting the potentials of biogas and methane production and “good” at predicting the reductions of total solids, volatile solids and chemical oxygen demand. The models obtained in this study can be used to reliably predict the parameters of the anaerobic biodigestion process of swine effluents in semi-continuous tubular biodigesters.

Em virtude da grande demanda por proteína de origem animal, tem-se aumentado a produção de frangos de corte e consequentemente a geração de resíduos provenientes do abate de aves, sendo necessário o desenvolvimento de técnicas que permitam o aproveitamento e reciclagem desses materiais. Objetivou-se com a execução deste trabalho avaliar a eficiência da compostagem no tratamento e reciclagem do resíduo sólido de abatedouro avícola. Utilizou-se resíduo sólido de abatedouro avícola comercial composto por fragmentos de vísceras, tecido muscular, adiposo e ósseo, sangue coagulado e penas e, como fonte de carbono, a casca de arroz. Montou-se uma leira com 1,5m3 de volume inicial, na qual foram monitorados os parâmetros: temperatura, teores de sólidos totais (ST), voláteis (SV), N, P, K, carbono orgânico (C), matéria orgânica compostável (MOC), matéria orgânica resistente à compostagem (MORC), demanda química de oxigênio (DQO), massa e volume enleirados, número mais provável (NMP) de coliformes totais e termotolerantes, bem como suas reduções durante o processo. A temperatura máxima atingida no centro da leira foi de 53,3ºC (média semanal), já as reduções de massa de ST e SV e volume durante o processo de pré-compostagem foram de 36,1; 44,3 e 23,3%, respectivamente, e, durante o processo de compostagem, foram de 21,8; 23,8 e 4,4%. A baixa redução do volume das leiras pode estar associada à alta concentração de MORC (40,1%) que pode ser principalmente relacionada à qualidade da fonte de carbono. O processo promoveu satisfatórias reduções totais de ST, SV e volume, sendo, respectivamente, 50,1; 57,5 e 26,7%. No entanto, foram observadas reduções de 43% na quantidade de nitrogênio presente no composto final. Apesar das reduções de nitrogênio, a compostagem demonstrou ser um método eficiente no tratamento dos resíduos sólidos de abatedouro avícola.

The great demand for animal protein was responsible for the increase on the broilers production and hence, the generation of waste from the poultry slaughter was increased as well, which in turn, propelled the development of techniques that allow the reuse and recycling of these wastes. The objective of this study was to evaluate the efficiency of composting on the treatment and recycling of solid waste from poultry slaughterhouse. The solid waste was from a commercial poultry slaughterhouse and was composed of viscera, muscle, fat, bone, blood and feathers that was mixed with a source of carbon, rice husk. Initially, a windrow with a volume of 1.5m3 was built, and then some parameters were monitored: temperature, total solids (TS), volatile (VS), N, P, K, organic carbon (C), composting organic matter (COC), organic matter resistant to composting (MORC), chemical oxygen demand (COD), mass and volume of the windrow, most probable number (MPN) of total and fecal coliforms, as well as their reductions during the process. The maximum temperature reached in the center of the windrow was 53.3°C (weekly average) since reductions of weight of TS and VS and volume during the pre-composting were 36.1, 44.3 and 23.3%, respectively and during the composting process was 21.8, 23.8 and 4.4%. The low volume reduction can be associated with high concentrations of MORC (40.1%) which can be mainly related to the quality of the carbon source. The process produced satisfactory total reductions of TS, VS and volume that were respectively, 50.1, 57.5 and 26.7%. However reductions were observed in 43% of amount of nitrogen in the final compound. Despite reductions in nitrogen content, composting proved to be an effective method in the treatment of solid waste from poultry slaughterhouse.

Background The aim of the present study was to assess the genetic diversity of Pantaneiro sheep, using microsatellite markers, in order to assist maintenance and management plans, enhance mating systems and reduce the inbreeding rate. A total of 127 animals were genotyped at eight microsatellite loci. They belonged to populations from the Experimental Farm of the Universidade Federal da Grande Dourados (UFGD) (Dourados/MS/Brazil) and Embrapa Pantanal (Corumbá/MS/Brazil). Results The population of Pantaneiro sheep from the UFGD exhibited a high mean number of alleles (11.13) and allelic richness (10.66). The polymorphic information content was highly informative in the locus studied, resulting in a mean value of 0.71. Observed heterozygosity was lower than expected for all molecular markers assessed. The analysis of molecular variance showed a differentiation rate of 5.2% between populations. Conclusions The results of the statistical parameters indicated that populations of Pantaneiro sheep require special attention on herd management, and it's further necessary to implement breeder exchange programs in order to preserve the genetic variability of these populations. Furthermore, the maintenance of those populations in their typical habitats is rather required to allow different responses from the herds to the interactions between genotype and environment.

O objetivo do trabalho foi verificar a eficiência da co-digestão anaeróbia dos dejetos suínos com crescentes níveis de adição de óleo de descarte e lipase. Foram testadas quatro doses de óleos (8, 12, 16 e 20g kg-1 de substrato) e 3 doses de lipase (1, 2 e 3g kg-1 de substrato). Os parâmetros avaliados foram: redução de sólidos totais (ST), sólidos voláteis (SV) e número mais provável (NMP) de coliformes totais (CT) e termotolerantes (CTT), além do pH, demanda química de oxigênio (DQO), produção e potenciais de produção de biogás. Os resultados demonstraram que houve influência das adições de óleo e lipase sobre as reduções de ST SV e pH do efluente, seguindo um modelo de predição linear e decrescente. As reduções do NMP de CT e CTT foram mais elevadas nos tratamentos com maior adição de óleo e lipase. A produção de biogás apresentou uma correlação negativa com as adições de lipase, sendo que estas proporcionaram efeito linear decrescente sobre os potenciais de produção de biogás/kg de dejeto, ST e SV adicionado. As adições de óleo e lipase não proporcionam efeitos favoráveis sobre as produções de biogás.

The goal this paper was to verify the efficiency of the anaerobic co-digestion of manure with increasing levels of added oil disposal and lipase. Were tested four levels oil (8, 12, 16 and 20 g kg-1 substrate) and 3 doses of lipase (1, 2, 3g-1 kg of substrate). The parameters evaluated were: reduction of total solids (TS), volatile solids (VS) and most probable number (MPN) of total coliforms (TC) and thermophilic (TTC), in addition to pH, chemical oxygen demand (COD), production and potential biogas production. The results demonstrated the influence of additions of oil and lipase to the reductions in SV and ST effluent pH, following a model of linear prediction and descending. The reductions in MPN of TC and TTC were higher in treatments with more adding oil and lipase. Biogas production showed a negative correlation with the additions of lipase, and these yielded linear effect on the potential of biogas/kg of manure, ST and SV added. The additions of oil and lipase did not provide favorable effects on biogas production.

O sequenciamento de Sanger, ou identificação das bases moleculares do DNA por terminação da cadeia, é um dos métodos amplamente utilizados para estudos moleculares. O uso da região citocromo b do DNA mitocondrial como marcador molecular se justifica pela presença de regiões conservadas e variáveis que podem ser sequenciadas e utilizadas em análises filogenéticas em diferentes níveis taxonômicos. O objetivo deste trabalho foi avaliar a variação do DNA mitocondrial por meio de sequenciamento de Sanger. Para tanto, amostras de tecido sanguíneo de ovinos do grupamento genético Pantaneiro (n=14), Bergamácia (n=4), Dorper (n=5) e Ile de France (n=5) foram utilizadas para extração de DNA. Logo em seguida as amostras foram submetidas a procedimentos de amplificação, purificação e sequenciamento. As análises estatísticas foram realizadas nos programas BioEdit 7.3.1.0 e MEGA 5.10. A utilização de primers internos e externos possibilitou o sequenciamento de 86% da região do citocromo b, o que indicou menor perda de nucleotídeos que acontece na reação de sequenciamento com apenas um par de primers. Os cálculos de diversidade média da região sequenciada permitiram observar baixa variação genética na população, evidenciando a natureza conservada do DNA herdado maternalmente. O sequenciamento parcial da região do citocromo b foi capaz de mostrar a variação do DNA mitocondrial em ovinos de 4 raças diferentes e proporcionou gerar dados para a realização de estudos futuros de origem e evolução dos animais.

The objective of this study was to analyze the influence of genetic group (GG) of the calf during gestation, mobilization of body reserves and period of postpartum anestrus in Nellore cows. Thirty-seven primiparous and multiparous cows were used: 24 gave birth to Nellore (NEL), and 13 gave birth to ½ Simmental × ½ Nellore (SIM) calves. According to the date of calving, cows were divided into three blocks, with intervals of 20 days between blocks. The body condition (BC) of the cows was estimated subjectively on a scale from 0 to 5 points, with intermediate grading of 0.5 points. We measured the thickness of subcutaneous fat (SF) between the 12th and 13th ribs and rump by ultrasound. Blood samples from each cow were collected weekly from the third week after birth until weaning, to analyze the level of progesterone; in the samples collected until 16 weeks postpartum, we analyzed the concentration of nonesterified fatty acids (NEFA). The gestation period of mothers of NEL calves was eight days longer, on average. The variables relating to the mobilization of body reserves (NEFA, BC and SF) were not influenced by calf GG, with the only significant effects being the number of days postpartum, with a peak in the concentration of NEFA between the sixth and eighth weeks and linear decrease in BC and NF. Mothers of NEL calves remained in anestrus for 4.6 weeks longer than the mothers of crossbred calves.

O objetivo deste trabalho foi avaliar os efeitos de marinadas com soluções alcalinas sobre características da carne de porco submetida a quedas do pH post-mortem, em músculo de porco. O pH das carcaças foi medido em abatedouro comercial (n = 526), aos 45 min pós-abate (pH45) e, em seguida, as carcaças foram divididas em grupos com pH45<5,7 ou pH45>5,7. Dez amostras do músculo longissimus dorsi de cada grupo foram coletadas e distribuídas em delineamento inteiramente casualizado, em arranjo fatorial 2x4, com duas condições (pH45<5,7 ou pH45>5,7) e quatro soluções de marinação: TC, controle sem marinação; TM1, bicarbonato de sódio e cloreto de sódio; TM2, tripolifosfato de sódio e cloreto de sódio; TM3, bicarbonato de sódio, tripolifosfato de sódio e cloreto de sódio. Não houve interação entre o pH45 da carne e os tratamentos marinados. As carnes com pH45<5,7 apresentaram maior luminosidade, perda por purga (PP), perda de exsudato (PE), perda de peso por cozimento (PC) e força de cisalhamento (FC). A marinação aumentou o pH da carne, reduziu a luminosidade, PE, PC e FC, e melhorou a maciez, suculência e palatabilidade. As marinadas com soluções alcalinas de cloreto, bicarbonato e tripolifosfato de sódio são eficazes no melhoramento da qualidade da carne suína, o que torna as características físicas das carnes processadas com marinadas semelhantes às da carne in natura, em consequência da acelerada glicólise post-mortem.

The objective of this work was to evaluate the effects of alkaline solution marinades on the characteristics of pork subjected to post-mortem pH decrease in pig muscle. The pH of carcasses was measured in a commercial slaughterhouse (n = 526), 45 min after slaughtering (pH45) and, then, the carcasses were divided into the groups with pH45<5.7 or pH45>5.7. Ten samples of the longissimus dorsi muscles of each group were collected and distributed in an entirely randomized design, in a 2x4 factorial arrangement, with two conditions (pH45<5.7 or pH45>5.7), and four marinade solutions: TC, no marinade; TM1, sodium bicarbonate and sodium chloride; TM2, sodium tripolyphosphate and sodium chloride; TM3, sodium bicarbonate, sodium tripolyphosphate and sodium chloride. There was no interaction between pH45 of the meat and the marinade treatments. Meat with pH45<5.7 showed higher values for lightness, and for purge loss (PL), exudate loss (EL), cooking loss (CL) and shear force (SF). Marinating increased the pH, reduced the lightness, EL, CL and SF, and improved tenderness, juiciness and flavor of meat. Marinades with solutions containing chloride, bicarbonate, and sodium tripolyphosphate are effective in the improvement of pork quality, making physical characteristics of marinated meat similar to those of fresh pork, as a consequence of accelerated postmortem glycolysis.

The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, and the fixed effects of contemporary group, milking number and age of the cow at calving as linear and quadratic covariables. Contemporary groups were defined by herd-year-month of test for test-day yields and by herd-year-season of calving for 305-day yields. The heritability estimates obtained by two-trait analysis ranged from 0.15 to 0.24 for milk, 0.16 to 0.23 for protein and 0.13 to 0.22 for fat, yields. Genetic and phenotypic correlations were all positive. The observed population additive genetic variation indicated that selection might be an effective tool in changing population means in milk, fat and protein yields.