Metabolic profile of Holstein cows : reference values in herds of Rio Grande do Sul - Brazil

Background: Assessing data from metabolic profile is a complex task depending on individual factors such as breed, age, sex and physiological status and environmental factors such as climate and management. Therefore, reference intervals produced in herds from different geographic regions are not always precise in the local reality. The aim of this study is to compile results of values of the most used parameters in the metabolic profile of healthy Holstein cows, grouped by lactation stage, obtained from studies in Rio Grande do Sul, Brazil, as an effort for the elaboration of regional reference intervals for dairy cattle in this geographic area. Materials, Methods & Results: The research was defined through the PICO strategy, considering multiparous Holstein cows from scientific studies carried out in Rio Grande do Sul, during the period 1996-2021, in which the nitrogen, glycidic, lipidic, enzymatic or mineral metabolic profile was determined. Google Scholar, Scientific Electronic Library and PubMed were the electronic databases selected for the search, using the following descriptors: “profile” and “metabolic” and “metabolic profile” and “dairy” or “cattle” or “cow” and “Brazil” and “southern” or “Rio Grande do Sul”. Studies in Portuguese, English and Spanish languages were considered. The references of the articles initially selected were also verified, through ResearchGate and Google Scholar, in addition to unpublished data, unfinished studies or data in the so called “gray literature”. It was possible to identify a total of 34 publications, which were tabulated to assess the scientific quality and bias risk. Studies were evaluated by a pair of independent reviewers, in order to compare results. Eligibility confirmation was given after the complete reading of the articles, evaluating the presence of all the inclusion selection criteria, such as adequate population and the intervention made. Examples of exclusion criteria for studies were studies or data duplication and methodological flaws that could compromise reliability. Thus, of the 34 studies selected in the initial screening, 14 remained. Thereafter, observational studies were preferably sought for data extraction. In the case of clinical trials, only data from control groups were used, in order to avoid disturbances due to interventions or treatments that could be applied. The reference intervals or means of the evaluated metabolites extracted from these studies were grouped in tables, in order to facilitate the comparison with research results obtained in different regions or even for comparison with future studies in the region of interest. Discussion: This retrospective study obtained mean values and standard deviation of the most used parameters in the metabolic profile of Holstein cows, grouped by lactation stage, obtained from studies performed in the state of Rio Grande do Sul, Brazil. Divergences were observed in several evaluations, especially in values of albumin, beta-hydroxybutyrate, aspartate transaminase and calcium, in spite of all data represented healthy animals from research trials with adequate environment and diet. It is important to consider the risk of time bias in this study, as within this 25-year period there was a very large evolution in dairy farming and some values may not be fully representative of current management systems in Holstein herds. Nevertheless, the results reinforce the importance of using regional reference values for the proper interpretation of metabolic profile results in dairy cows. In addition, the proposing of database index for regional averages or reference intervals, is useful for comparing results of metabolic profiles carried out in different geographic regions, in future studies to be performed in this particular region, or even to be utilized by field practitioners of this particular region

Relationships among blood calcium, phosphorus and magnesium concentration and the dietary cation-anion difference in peripartum dairy cows

O período transição impõe um grande desafio na homeostase do cálcio em bovinos leiteiros, sendo que a hipocalcemia subclínica tem sido correlacionada à maior incidência de enfermidades infeciosas e metabólicas no pós-parto. A grande variabilidade na calcemia que ocorre entre indivíduos, sistemas de produção e entre regiões geográficas, dificultam o estabelecimento de um ponto de corte preciso e explica a variabilidade nos resultados de pesquisas desenvolvidas em diferentes países. Atualmente, a principal estratégia de prevenção e controle de hipocalcemia clínica e subclínica consiste na utilização de dietas aniônicas no pré-parto. Apesar de seus efeitos benéficos na calcemia no pós-parto estarem bem estabelecidos, poucos são os estudos avaliando seus efeitos nos níveis de fósforo e magnésio, minerais cujo metabolismo é intimamente relacionado ao cálcio. O objetivo deste trabalho foi identificar a influência da DCAD sobre os níveis séricos de cálcio (total, total corrigido e ionizado), fósforo e magnésio, de vacas leiteiras no período do periparto, na região do Planalto Médio no estado do Rio Grande do Sul, bem como, observar sua interação com as variáveis paridade e tempo, além de propor intervalos de referência regionais para estes minerais. Foram utilizadas 56 vacas de raça Holandesa (18 primíparas e 38 multíparas), em 6 propriedades comercias de produção intensiva. Amostras de sangue para determinação dos níveis séricos de cálcio total e ionizado, fósforo, magnésio e albumina foram coletadas nos momentos -7, +7, +14 e +28 dias em relação ao parto; amostras de urina foram coletadas no momento –7 para mensuração do pH urinário e a amostras pareadas de alimento foram coletadas em cada visita para determinação dos níveis de cálcio, fósforo, magnésio e DCAD. Os valores de cálcio total foram corrigidos de acordo com a concentração de albumina sérica. Houve correlação positiva entre a DCAD pré-parto e cálcio total (p = 0,02) e cálcio total corrigido (p = 0,01) no momento -7, não ocorrendo interação entre a DCAD pré-parto e o cálcio nos demais momentos avaliados. Observou-se correlação negativa entre a DCAD pré-parto e os níveis de magnésio no momento -7 em relação à data do parto (p = 0,02), porém esta correlação não ocorreu nos demais períodos avaliados. Não houve influência da DCAD na fosfatemia em nenhum período avaliado. Além disso, foi possível observar que a definição de prevalência de transtornos subclínicos de cálcio, fósforo e magnésio podem variar em função do ponto de corte utilizado, além de ocorrer grande variabilidade nas concentrações séricas dos minerais de acordo com a paridade (primípara ou multípara) e do momento da coleta. Os resultados podem fornecer valores de referência dos minerais estudados para rebanhos leiteiros no Rio Grande do Sul.The transition period imposes a great challenge for calcium homeostasis in dairy cattle. Subclinical hypocalcemia has been correlated with a higher incidence of infectious and metabolic diseases in the postpartum period. Serum calcium levels results varies considerable between individuals, production systems and geographic regions, making it difficult to establish a precise cut-off point for calcium. This partially explains the discordances among studies carried out in different regions. Currently, anionic salts are the main strategy for control and prevention of clinical and subclinical hypocalcemia during the transition period. Although its beneficial effects on postpartum calcemia are well established, few studies have evaluated the effects of DCAD on serum levels of P and Mg, minerals whose metabolism is closely related to Ca. The aim of this study was to evaluate the influence of DCAD on serum levels of calcium (total and ionized), phosphorus and magnesium in dairy cows during the peripartum period, at the Middle Plateau region of Rio Grande do Sul (Southern Brazil), as well as to observe its interaction with parity and time of observation, in addition to propose a regional reference interval for these minerals. A total of 56 Holstein cows (18 primiparous and 38 multiparous), from 6 different farms, with confined production systems, were enrolled in this study. Blood samples were collected to determine the serum levels of total and ionized calcium, phosphorus, magnesium and albumin at -7, +7, +14 and +28 days in relation to parturition; urine samples were collected at day -7, for urinary pH measurement and paired food samples were collected at each visit for determination of calcium, phosphorus, magnesium and DCAD levels. Values of total calcium were corrected according to serum albumin concentration. There was a positive correlation between prepartum DCAD and total Ca (p = 0.02) and corrected total Ca (p = 0.01) at time -7. No interactions occurred between prepartum DCAD and calcium values in the other periods evaluated. A negative correlation between prepartum DCAD and magnesium levels occurred at time -7 in relation to parturition (p = 0.02), but this correlation did not occur in the other periods evaluated. There was no influence of prepartum DCAD on phosphatemia in any period evaluated. Furthermore, the results suggest that the definition of prevalence for subclinical disorders of calcium, phosphorus and magnesium may vary depending on the cutoff point used. In addition, the study shows that the serum concentration of these minerals is greatly influenced by factors such as parity and timing of analysis. The results can provide reference values of the studied minerals for dairy herds in Rio Grande do Sul