Maria Edi Rocha Ribeiro

Avaliação da qualidade do leite na bacia leiteira de Pelotas, RS. Efeito dos meses do ano

RESUMO - Os efeitos dos meses do ano sobre a composicao e producao do leite foram avaliados atraves do acompanhamento de 10 unidades produtoras de leite, divididas em tres sistemas de producao classificados como especializado (ES), semi-especializado (SE) e nao-especializ ado (NE), durante 11 meses do ano. Foram coletadas amostras de leite diretamente dos tanques refrigeradores para determinacao das caracteristicas fisico-quimicas e contagem de celulas somaticas (CCS). Quantificaram-se a incidencia de mastite e a producao media de leite (litros/vaca/dia) e coletaram-se amostras de agua utilizada para consumo e limpeza, de pastagem, concentrado e silagem. O delineamento adotado foi o completamente casualizado, em arranjo fatorial desbalanceado, considerando como fatores os meses do ano, os sistemas de producao e a sua interacao. Nao foi encontrada variacao significativa entre os meses estudados para producao de leite, valores de crioscopia, porcentagens de gordura, extrato seco, nitrogenio nao-proteico, CCS, composicao quimica, contagem de coliformes da agua e composicao bromatologica do concentrado. Os maiores valores de proteina verdadeira do leite foram observados em outubro e novembro, enquanto os maiores de caseina, em outubro, novembro, marco e abril. O extrato seco desengordurado foi superior em dezembro e a acidez variou juntamente com a incidencia de mastite, sendo superior nos meses de novembro e maio. Em relacao a proteina bruta, ocorreu interacao entre meses e sistemas. Foram observadas correlacoes negativas entre producao de leite e gordura, mastite e CCS, e correlacao positiva entre producao de leite e lactose. O leite produzido nos diversos meses do ano diferiu, principalmente, quanto a incidencia de mastite, fracao proteica, extrato seco desengordurado e acidez. A qualidade da agua nao se modificou expressivamente nos meses em que foi amostrada e se apresentou dentro dos limites considerados aceitaveis.

Produção e qualidade do leite na bacia leiteira de Pelotas-RS em diferentes meses do ano

We evaluated changes in milk production and quality during 11 months in nine milk production units, randomly chosen at the Pelotas dairy region. Mastitis incidence and average milk daily production were registered. Once a month, animal feed and bulk milk samples were collected at each production unit for further physical-chemical analysis and somatic cells count. Production units were classified in one of the following production systems: specialized, semi-specialized and not specialized. Analysis of variance was used to evaluate the effects of months, production systems and their interaction, according to a completely randomized design. Fat corrected milk production, crude protein, casein, lactose, total solids, solids non fat contents of the milk and mastitis incidence varied among months, but fat and non protein nitrogen contents and somatic cells count did not. In fall and winter, values for milk production and milk components contents were the lowest, while mastitis incidence was highest in spring and summer.

Fornecimento de suplementos com diferentes níveis de energia e proteína para vacas Jersey e seus efeitos sobre a instabilidade do leite

Objetivou-se avaliar o efeito de suplementos contendo tres combinacoes de energia e proteina sobre a producao leiteira, as caracteristicas fisico-quimicas do leite, o peso e a condicao corporal e o perfil bioquimico sanguineo de vacas. Foram utilizadas 24 vacas lactantes em campo natural, distribuidas em delineamento completamente casualizado, recebendo um dos seguintes suplementos: baixos niveis de energia e proteina; baixo nivel de energia e alto nivel de proteina; ou altos niveis de energia e proteina. Em comparacao ao suplemento com baixos niveis de energia e proteina, aquele com altos niveis de energia e proteina reduziu a instabilidade do leite na prova do alcool, aumentou em 50% a producao de leite e em 18% o escore de condicao corporal das vacas. Alem disso, ocasionou aumento dos componentes do leite e do perfil bioquimico sanguineo das vacas: 13% no teor de lactose; 9% no de extrato seco desengordurado; 21% nos niveis plasmaticos de glicose; 24% no teor de fosforo; 16% no nivel de creatinina; 9% no teor de magnesio; e reduziu em 40% o teor de nitrogenio ureico. O suplemento com altos niveis de energia e proteina foi mais eficiente que os demais em melhorar a estabilidade do leite na prova do alcool, o escore de condicao corporal e os teores de alguns componentes quimicos do leite e do sangue.

Produção leiteira, composição do leite e perfil bioquímico sanguíneo de vacas lactantes sob suplementação com sal aniônico

The objective of this work was to evaluate the inclusion of anionic salt in the diet on the physical characteristics and chemical composition of milk, biochemical blood profile, milk yield, body weight and condition. It was used 20 Jersey cows, distributed into two diets, a diet with no addition of anionic salt and one diet with addition of 0.25 kg/day of ammonium chloride. It was used a completely randomized design. Cows supplemented with anionic salt presented lower urinary pH and increase of blood contents of urea, calcium and magnesium. With the anionic diet, milk precipitated with lower ethanol concentration and it presented lower density, percentages of lactose, protein and immunoglobulin, but higher ionic calcium content. Supply of anionic diet during lactation resulted in metabolic acidosis, which altered the blood biochemical profile and milk physical-chemical characteristics.

Ocorrência do leite instável não ácido no noroeste do Rio Grande do Sul

ABSTRACT The unstable non-acid milk (UNAM) is characterized by loss of casein stability, which results in its precipitation at the alcohol test even though titratable acidity be lower than 18oD. This trial aimed to estimate the occurrence of UNAM in the Northwest of Rio Grande do Sul, state and to verify seasonal variation and its effects on milk composition. From September 2002 to August 2003, approximately 200 dairy farms were monthly monitored. Milk samples from bulk tank were collected and analyzed for titratable acidity; precipitation at alcohol 76% test; percentages of fat, crude protein, lactose, total solids; and somatic cells count, totalizing 2,396 milk samples. UNAM occurrence was 55.2%, being highest in February and March 2002. UNAM occurrence was reduced as milk production of farms increased. Fat percentage did not vary between normal milk and UNAM. However, crude protein, lactose, total solids, and solids non-fat contents were lower in UNAM than in normal milk. Keywords: milk composition, milk quality, stability, alcohol test

Leite instável não ácido: um problema solucionável?

This paper aimed to present the main results about the unstable non acid milk (LINA). The proportion of milk samples with thermal stability below the Brazilian dairy industry standard is a serious problem, with highest occurrence at short food supply periods. It is a multi factorial problem, which causing factors are related to test execution (ethanol concentration used), to management (feeding, climate, human-animal relation), to animal (stress susceptibility, productive potential, lactation stage, sanitary condition, digestive and metabolic disorders), among others. There are doubts to the accuracy and precision of the alcohol test to detect stability problems. Dairy industry needs a fast, low price and easy test, but that can identify milk suitable to thermal processing. An adequate animal’s management besides realistic parameters of milk test might contribute to improve milk stability.

Caracterização eletroforética de proteínas e estabilidade do leite em vacas submetidas à restrição alimentar

The objective of this work was to evaluate the feeding restriction effects on milk yield and on its electrophoretic protein profile, and to relate them to milk stability to the alcohol test. Two experiments were carried out with Jersey cows: in the first one, the effect of 40% feed restriction was evaluated on semiconfined cows; in the second one, the effect of 30% reduction in total digestive nutrients was evaluated on confined cows. Protein fractions were determined by electrophoresis and their quantification was done by image analysis. Milk samples were classified according to their stability in the 72°GL‑alcohol test. The 40% feed restriction for semiconfined cows decreased milk yield, but it did not change milk protein contents and stability; in this case, unstable milk showed larger contents of β‑casein and total proteins, but lower κ‑casein in comparison to stable milk. The 30% restriction of energy supply for confined cows did not reduce milk yield, but decreased the percentage of serum bovine albumin and milk stability; in this case, unstable and stable milk did not differ as for protein fractions.

Suplementação de vacas holandesas em estádio avançado de lactação

The trial aimed to verify the effects of two feeding supplements: low and high level supplementation given to cows at an extended lactation stage upon productive aspects, physical-chemical composition of milk and blood biochemical profile. Twelve lactating Holstein cows, with 514kg of body weight, body condition score of 3.5, yielding 13L milk cow-1 day-1 and approximately 349 days of lactation were used. Treatments were low or high level of supplementation for lactating cows grazing natural range pasture. Cows body weight and body condition score, individual milk yield, physical and chemical characteristics and somatic cells count, besides biochemical blood profile were evaluated. Increased nutrient supply augmented body weight gain, body condition score, fat corrected milk, milk fat and total solids contents, but did not change the others milk components nor blood biochemical profile. Increasing nutrient supply for cows at an extended lactation might be a valuable option to match milk productivity and improved physical aspects of dairy cows kept on grazing systems, without adverse effects upon milk components yield.

Efeito da suplementação com diferentes níveis de selênio orgânico e inorgânico na produção e na composição do leite e no sangue de vacas em lactação

The effects of the dietary supplementation with selenium were evaluated on the concentration of the mineral in blood and milk, as well as changes in milk yield, physical and chemical characteristics, and somatic cells count (SCC). The trial lasted 63 days, the first 21 were designed to adaptation of animals to experimental conditions and standard diet. Thirty-two lactating Jersey cows were used and, at the beginning of the trial, they presented body weight of 402.5+58.4kg, body condition score of 3.19+0.31, milk yield of 10.4+2.1kg/day, and 141.4+69.3 days in milking. Treatments were: control (standard diet without added selenium), inorganic selenium (standard diet + 0.3mg sodium selenite/kg concentrate - SI0.3), organic selenium 0.3 (standard diet + 0.3mg selenomethionine/kg concentrate - SO0.3), and organic selenium 0.6 (standard diet + 0.6mg selenomethionine/kg concentrate - SO0.6). Total daily amounts of selenium were 2.38, 4.18, 4.18, and 5.98mg/cow, respectively, for control, SI0.3, SO0.3, and SO0.6 treatments. The trial was conducted as a completely randomized design. The number of days in milking and the values for all attributes measured at the end of the adaptation period were used as covariates. Measurements of body weight and condition score, milk yield and composition, and blood composition were performed on days 0, 14, 28, and 42 of the experimental period. No differences were detected among treatments for milk yield and composition, body weight and condition score, physical-chemical characteristics of milk, somatic cells count, and biochemical profile of the blood, except for Se contents of blood of control compared to supplemented. There were no differences caused by selenium sources or levels. Selenium supplementation did not alter neither milk nor blood components.

Produção e qualidade do leite em sistemas de produção da região leiteira de Pelotas, RS, Brasil

This research was aimed at characterizing milk yield and quality of three production systems at Pelotas dairy region. From September 2001 up to August 2002, nine dairy production units were visited for 11 months. Production units were classified as specialized (S), partially specialized (PS) and non-specialized (NS). Bulk tank milk was sampled to analyze physical and chemical attributes and somatic cells count (SCC). Mastitis percentage and 4% fat-corrected milk yield were evaluated. A completely randomized split-plot design was adopted. Cryoscopic index differed between specialized and non-specialized systems (P<0.10), but all values were within the normal range. Specialized system showed lower mastitis occurrence than partially specialized and non-specialized systems (P<0.10). Production systems did not differ for 4% fat-corrected milk yield, contents of protein, casein, fat, lactose, solids non-fat, total solids, non-protein nitrogen, as well as titrable acidity and somatic cells count. Higher technology level application reduced mastitis occurrence, contributing to a better milk quality.