Potential benefits of a blend of essential oils on metabolism, digestibility, organ development and gene expression of dairy calves.

The objective of this study was to evaluate blood cells and metabolites, insulin-like growth factor-1 (IGF-1), digestibility, internal organs weight and histology, gene expression, and spleen cell proliferation of pre-weaned bull calves supplemented with a blend of essential oils in milk replacer (MR). Sixteen newborn Holstein × Gyr crossbred dairy bull calves, with body weight at birth of 33.3 ± 3.7 kg, were housed in individual sand bedded pens, blocked by genetic composition, and randomly assigned to 1 of 2 treatments in a randomized complete block design: Control (CON, n = 8) and blend of essential oils supplementation (BEO, n = 8, 1 g/day/calf, Apex Calf, Adisseo, China). The commercial blend was composed by plant extracts derived from anise, cinnamon, garlic, rosemary, and thyme. Animals were fed 5 L of MR/day reconstituted at 15% (dry matter basis), divided into two equal meals. Water and starter were provided ad libitum. ß-hydroxybutyrate, urea, and glucose were evaluated weekly, IGF-1 was evaluated biweekly, and total blood cell count was performed every four weeks until the end of the trial at eight weeks of age. Feed samples were collected three times a week and polled for weekly analysis. Apparent total nutrient digestibility was determined from d 56 to 60 of age. On d 60 ± 1, animals were euthanized for organ weight, histology, spleen cell proliferation, and intestinal gene expression analysis. Data were analyzed independently using linear mixed models using the REML method in the nlme package in R for continuous outcomes. A non-parametric test was used for ordered categorical outcomes using the Artools package in R. There were no differences between groups for blood evaluations, digestibility, gene expression, and a spleen cell proliferation assay. However, BEO calves presented a heavier pancreas, heavier intestines, bigger ileum villi, and higher cecum butyrate levels (P < 0.05), demonstrating that the EO supplementation helped intestinal development and symbiotic bacteria. It was also observed in CON animals' heavier respiratory tract and a higher eosinophil count (P < 0.05). Therefore, the organs where eosinophils are more active had a better response for BEO animals. No differences were found in the intestinal gene expression in the immune context. These results demonstrate that supplementing essential oils in MR could contribute to gut development and immune function. However, more research is needed to understand its impact on body development and define the best dosage and route of administration.

How to use recombinant bovine somatotropin in crossbred Holstein × Gyr (3/4 and 7/8) cows?

The aim of this study was to evaluate the effects of dose, start time, and application interval of recombinant bovine somatotropin (rbST) on performance, health, and reproduction parameters of crossbred Holstein × Gyr dairy cows (3/4 and 7/8). A 2 × 2 × 2 factorial study was designed to test the effects of application dose (250 mg rbST or 500 mg rbST), start of application (40 or 63 days in milk (DIM)), and application interval (12 or 14 days); 180 crossbred Holstein × Gyr cows were enrolled. Treatments with 500 mg rbST resulted in increased milk production, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM). In the factorial design analysis, greater FCM, ECM, and milk solid production (kg/day) were observed when 500 mg rbST was started at 63 DIM, while 250 mg rbST resulted in greater milk production (kg/day), FCM, ECM, and milk solids (kg/day) when administered at 12-day intervals. Administration of 500 mg rbST resulted in an increase of days open and number of services per pregnancy (P = 0.01). Holstein × Gyr cows (3/4 and 7/8) presented a superior productive response to rbST when treated with 500 mg starting at 63 DIM and at 14-day intervals.

Evaluation of Ingestive Behavior, Ruminal and Blood Parameters, Performance, and Thermography as a Phenotypic Divergence Markers of Residual Feed Intake in Rearing Dairy Heifers.

The objectives of this study were: (1) to identify and rank phenotypically divergent animals for residual feed intake (RFI) regarding their efficiency (high: HE or low: LE); (2) to evaluate their relationships with ingestive behavior, ruminal and blood parameters, performance, and infrared thermography; and (3) to determine if such measurements can be used as feed efficiency markers in rearing dairy heifers. Thirty-eight heifers, 143 d ± 4 (Mean ± SD) of age and 108.7 kg ± 17.9 of body weight were used. The animals were fed with a total mixed ration during the 91 d of the trial. A phenotypic divergence of DMI for RFI was observed between -0.358 and 0.337 kg/d for HE and LE, respectively. Dry matter intake (DMI) was lower in the HE (2.5 kg DMI/d vs. 3.1 kg DMI/d), as was the number of visits to the feed bin with consumption (59 vs. 71). Feed intake was the best predictor of said divergence. Water intake and number of visits to the feed bin were presented moderate correlations with RFI. The ruminal fermentation variables, blood metabolites, blood hormones (such as the other ingestive behavior variables), and infrared thermography were not able to accurately predict HE or LE animals.

Farm microbiological milk culture: study case on cow performance, financial and economic aspects / Cultivo microbiológico de leite na fazenda: estudo de caso sobre desempenho de vacas, aspectos financeiros e econômicos

This study evaluated the use of microbiological culture of milk from cows with clinical mastitis (CM), and the performance and economic results after implementing this procedure. The 18-month data were obtained from a farm in Minas Gerais State, Brazil, with an average daily production of 23.1 L of milk from cows milked twice daily under a semi-intensive regime. After a case of CM was identified, a milk sample from the affected quarter was collected and sent to the farm's laboratory. First, a bi-plate containing selective growth medium was used for isolation of Gram-positive and negative bacteria (Plate 1). Subsequently, a tri-plate with selective growth medium was used for isolation of Gram-positive and negative bacteria, and bacteria of the genus Streptococcus (Plate 2). Finally, a tri-plate containing three chromogenic culture media capable of identifying 18 bacterial species was used (Plate 3). Clinical cases of mastitis were treated once a day based on the results of the microbiological culture. Two economic scenarios were evaluated (scenarios 1 and 2). Scenario 1 compared the situation if all cases of CM were treated (not using on-farm culture) vs. the use of on-farm culture (real data) and the generated savings for one year. Data from 1,582 lactations of 1,227 cows were evaluated, with 1,917 cases of CM from 636 cows recorded. The average annual incidence of CM was 48.2%. Of all cases evaluated, 76.8% were classified as grade 1 mastitis; 20% as grade 2, and 3.2% as grade 3. The incidence of new clinical cases of mastitis was 4.17% per month. From the samples analyzed on the three plates, 27.8% of the cases received a recommendation to not be treated and 72.2% received a recommendation of treatment. However, only 18.6% were not treated, making a total of 81.4% treated cases. Of the clinical cases that did not receive intramammary antibiotic therapy, 84.3% had a clinical cure. Conversely, the clinical cure rate reached 84% for the cases that received intramammary antibiotic therapy. In scenario 1, the total operational cost of the clinical case decreased by 10.3% after the implementation of the on-farm culture, with an 18.4% reduction in the use of antibiotics. In scenario 2, there was a 5.5% reduction in the cost of the clinical case and an 11.8% reduction in the use of antibiotics. Thus, the implementation of on-farm culture and the applied methodology, enhanced treatment accuracy of CM cases, reducing the total operating cost of the case and the use of antibiotics on the farm.

O objetivo deste estudo foi avaliar a utilização da cultura microbiológica de leite de vacas com mastite clínica (MC), os resultados zootécnicos e econômicos após implementação desse procedimento. Dados de 18 meses foram obtidos em uma fazenda em Minas Gerais com produção média de 23,1 L de leite/vaca/dia, em duas ordenhas diárias em regime semi-intensivo. Após a identificação da MC, uma amostra de leite do quarto afetado foi coletada e encaminhada para laboratório da fazenda. Primeiramente foi utilizada placa bipartida em meio de cultura seletivo para crescimento de bactérias Gram-positivas e negativas (Placa 1), seguindo-se para a utilização da placa tri-partida com meios de cultura seletivos para crescimento de bactérias Gram-positivas e negativas e bactérias do gênero Streptococcus (Placa 2) e posteriormente para placa tripartida, contendo três meios de cultura cromogênicos, capazes de identificar 18 espécies bacterianas (Placa 3). Foram avaliados dados de 1.227 vacas em 1.582 lactações, sendo registrados 1.917 casos de MC. Os casos clínicos de mastite foram tratados uma vez ao dia com base nos resultados da cultura microbiológica. Foram realizadas duas avaliações financeiras (cenário 1 e 2). O cenário 1 comparou a situação se todos os casos de MC fossem tratados (ausência de cultura na fazenda), comparado com a utilização da cultura na fazenda (dados reais) e as economias de recursos geradas durante o período de um ano. O cenário 2 utilizou os resultados reais após a economia de recursos gerados pela cultura, seguindo a recomendação ideal de tratamento. Foram avaliados 1.917 casos de MC (636 animais), totalizando incidência média anual de 48,2%. Do total dos casos avaliados, 76,8% foram classificados como mastite grau 1; 20% grau 2 e 3,2% grau 3. A incidência de novos casos clínicos de mastite foi de 4,17% ao mês. Das amostras analisadas nas três placas, 27,8% dos casos receberam a recomendação de não serem tratados e 72,2% de tratamento. Entretanto, apenas 18,6% realmente não foram tratados, totalizando 81,4% de tratamentos. Dos casos clínicos que não receberam antibioticoterapia intramamária, 84,3% apresentaram cura clínica. Já os casos que passaram por antibioticoterapia intramamária, a taxa de cura clínica foi de 84,0%. No primeiro cenário, após a implementação da cultura na fazenda, o custo operacional total do caso clínico reduziu em 10,3%, com redução de 18,4% de utilização de antibióticos. Já no segundo cenário, houve redução de 5,5% no custo do caso clínico e redução de 11,8% na utilização de antibióticos. A implementação da cultura na fazenda e a metodologia aplicada, promoveu maior assertividade dos tratamentos dos casos de MC, com redução do custo operacional total do caso e da utilização de antibióticos na propriedade.

How Divergence for Feed Efficiency Traits Affects Body Measurements and Metabolites in Blood and Ruminal Parameters on Pre-Weaning Dairy Heifers.

The objectives of this study were: (1) to evaluate feed efficiency indexes and their relationships with body measurements and blood and ruminal metabolites in the pre-weaning period; (2) to determine if such measurements can be used as feed-efficiency markers during the pre-weaning period. Holstein-Gyr heifer calves (n = 36), enrolled between 4 and 12 weeks of age, were classified into two residual feed intake (RFI) and residual body weight gain (RG) groups: high efficiency (HE; RFI, n = 10; and RG, n = 9), and low efficiency (LE; RFI, n = 10; and RG, n = 8). Calves were fed whole milk (6 L/day) and solid feed ad libitum. Body developments were measured weekly and feed intake (milk and solid feed) daily during the whole period. Blood samples were collected at 12 weeks of age and analyzed for glucose, insulin and ß-hydroxybutyrate (BHB). Samples of ruminal content were collected on the same day and analyzed for pH, NH3-N, and volatile fatty acids (VFA). Among the growth characteristics, only the initial hip width differed between the RFI groups, and withers height differed between the RG groups. Concentration of BHB was greater and glucose: insulin ratios tended to be greater in LE-RG animals. Butyric acid proportions were similar among RFI groups, but tended to be greater for HE-RG than for LE-RG. Overall, correlation coefficients between RFI or RG and blood, rumen, or morphometric markers were low. Thus, it is unlikely that measurements of metabolic indicators, per se, will be useful in the early identification of more efficient animals. Understanding the underlying physiological basis for improved feed efficiency in dairy heifers requires further investigation.

Effects of Bulk Tank Milk, Waste Milk, and Pasteurized Waste Milk on the Intake, Ruminal Parameters, Blood Parameters, Health, and Performance of Dairy Calves.

The aim of this study was to evaluate the effects of bulk tank milk (BTM), WM, and PWM on the intake, ruminal parameters, blood parameters, health, and performance of dairy calves. Forty-five male crossbred dairy calves (Gyr × Holstein) were used. On their fourth day of age, animals were grouped according to body weight, serum protein levels, and genetic composition. Three treatments were assessed: BTM (n = 15), WM from cows in antibiotic treatment (n = 15), and PWM via high-temperature, short-time pasteurization (72-74 °C for 16 s) (n = 15). During the experimental period (from 4 to 60 d of age), animals were fed 6 L of milk/d, divided into two equal meals. Water and concentrate were provided ad libitum. Daily measurements were made for milk, concentrate, and water intakes, as well as for fecal and respiratory scores. Rumen fluid and blood were sampled weekly. The following parameters were evaluated: volatile fatty acids (VFAs), pH and ammonia-N in rumen fluid, and ß-hydroxybutyrate (BHB) and glucose in blood. Animals were weighed at birth, 4 d of age, and weekly up to 60 d of age. At the end of the experimental period (60 ± 1 d), all animals were euthanized for pulmonary evaluation. The randomized complete design with an interaction between treatment and week was the experimental method of choice for testing the hypothesis of the treatment's effect on all evaluated outcomes. Animals in the BTM treatment had higher milk dry matter intake (DMI), followed by WM and PWM calves. Concentrate DMI was lower for BTM in comparison to WM and PWM calves. However, total DMI showed no significant differences between treatments. The rumen fluid from calves receiving PWM had higher concentrations of acetate and propionate than that of BTM and WM animals. No differences were observed between treatments for blood glucose and BHB concentrations. Health parameters (fecal and respiratory scores) and pneumonia occurrence showed no significant difference between treatments. No differences were observed for average daily gain (ADG) or body growth. Feeding WM and PWM did not show significant negative effects on the intake, ruminal parameters, blood parameters, health, or performance of dairy calves.

Screening microchip sites to predict body temperature in young calves.

Thermal microchip sensors can automate body temperature measurements. The best site of implantation is still unknown, and the accuracy and precision of body temperature predictions based on microchip data need to be investigated. The aim of this study was to investigate the best site for microchip implant for monitoring body temperature in dairy calves. Seventeen calves were used (32.2 ± 5.2 kg of body weight) and the microchips were implanted four days after birth. The microchips were implanted at navel, ear and tail base (subcutaneous), neck (cleidocephalicus) and internal face of leg (gracilis) (intramuscular). Rectal temperature (RT, °C), obtained with a clinical thermometer, was considered as core temperature. Air temperature (AT), relative humidity (RH) and the temperature and humidity index (THI) were evaluated at the same time of rectal and microchip temperature measurements over 56 days. The range of AT, RH and THI was 7.6-34.4 °C, 17.5-99.0% and 50.6 to 91.5. The average for rectum, ear, neck, tail, leg, and navel were 38.7; 36.9; 38.0; 37.0, 37.8 and 37.0 °C. The intramuscular implantations had closest values to RT. The correlations between RT and ear, neck, tail, leg, and navel temperatures were 0.56, 0.60, 0.60, 0.53 e 0.48. The RT prediction based on microchip data had precision (rc) ranged between 0.49 and 0.60 and accuracy (Cb) between 0.79 and 0.88. The inclusion of AT, RH and THI as predictive variables in models decrease the mean absolute error (23%) and increase the precision (21.3%) and accuracy (10.2%). The Concordance Correlation Coefficient and root-mean-square error for equations using tail or neck microchips were 0.68 and 0.67, and 0.29 and 0.28 °C, respectively. The tail base is a promising site for microchip implantation to predict rectal temperature. The inclusion of air temperature as a predictive variable in the models is recommended.