Effect of somatic cell count and mastitis pathogens on milk composition in Gyr cows

Abstract Background Gyr cows are well adapted to tropical conditions, resistant to some tropical diseases and have satisfactory milk production. However, Gyr dairy herds have a high prevalence of subclinical mastitis, which negatively affects their milk yield and composition. The objectives of this study were (i) to evaluate the effects of seasonality, mammary quarter location (rear x front), mastitis-causing pathogen species, and somatic cell count (SCC) on milk composition in Gyr cows with mammary quarters as the experimental units and (ii) to evaluate the effects of seasonality and somatic cell count (SCC) on milk composition in Gyr cows with cows as the experimental units. A total of 221 lactating Gyr cows from three commercial dairy farms were selected for this study. Individual foremilk quarter samples and composite milk samples were collected once a month over one year from all lactating cows for analysis of SCC, milk composition, and bacteriological culture. Results Subclinical mastitis reduced lactose, nonfat solids and total solids content, but no difference was found in the protein and fat content between infected and uninfected quarters. Seasonality influenced milk composition both in mammary quarters and composite milk samples. Nevertheless, there was no effect of mammary quarter position on milk composition. Mastitis-causing pathogens affected protein, lactose, nonfat solids, and total solids content, but not milk fat content. Somatic cell count levels affected milk composition in both mammary quarters and composite samples of milk. Conclusions Intramammary infections in Gyr cows alter milk composition; however, the degree of change depends on the mastitis-causing pathogen. Somatic cell count is negatively associated with reduced lactose and nonfat solids content in milk. Seasonality significantly affects milk composition, in which the concentration of lactose, fat, protein, nonfat solids and total solids differs between dry and wet seasons in Gyr cows.

Effects of in vitro selenium supplementation on blood and milk neutrophils from dairy cows

The study was designed to assess the effects of in vitro selenium addition on intracellular hydrogen peroxide production by neutrophils from the milk and blood of dairy cows. Blood from 10 dairy cows and 20 milk samples from five dairy cows were incubated with 0 mg (control) or 10μM of sodium selenite. Then, milk and blood neutrophils were submitted for evaluation of intracellular hydrogen peroxide production by flow cytometry using 2',7'-dichlorofluorescein diacetate as a probe. The selenium status of the animals was evaluated by determination of the blood glutathione peroxidase activity. The results of the present work showed that in vitro selenium supplementation leads to an enhancement in intracellular hydrogen peroxide production, which indicates an improvement in the bactericidal effects of blood and milk neutrophils even in cows with a selenium-adequate status. Thus, the present study showed that in vitro Se supplementation leads to an enhancement in intracellular hydrogen peroxide production, indicating an improvement in the bactericidal effects of blood and milk neutrophils in cows with Se-adequate status.

Density and rheological parameters of goat milk

The rheological behavior and density of goat milk was studied as a function of solids concentration (10.5 to 50.0%) and temperature (273 to 331 k). Newtonian behavior was observed for values of total solids (TS) between 10.5 and 22.0% and temperatures from 276 to 331 k changing to pseudoplastic behavior without yield stress for TS from 25.0 to 39.4% at the same range of temperature. Goat milk with TS between 44.3 to 50.0% and temperatures of 273 to 296 k showed yield stress in addition to pseudoplastic behavior. At 303 to 331 k the power law model was observed again, without yield stress. The density of goat milk ranged from 991.7 to 1232.4 kg.m-3.

Validation of models for predicting milk urea nitrogen concentrations, estimating dry matter intake by the NRC (2001)

The objective of this study was to validate three different models for predicting milk urea nitrogen using field conditions, attempting to evaluate the nutritional adequacy diets for dairy cows and prediction of nitrogen excreted to the environment. Observations (4,749) from 855 cows were used. Milk yield, body weight (BW), days in milk and parity were recorded on the milk sampling days. Milk was sampled monthly, for analysis of milk urea nitrogen (MUN), fat, protein, lactose and total solids concentration and somatic cells count. Individual dry matter intake was estimated using the NRC (2001). The three models studied were derived from a first one to predict urinary nitrogen (UN). Model 1 was MUN = UN/12.54, model 2 was MUN = UN/17.6 and model 3 was MUN = UN/(0.0259 × BW), adjusted by body weight effect. To evaluate models, they were tested for accuracy, precision and robustness. Despite being more accurate (mean bias = 0.94 mg/dL), model 2 was less precise (residual error = 4.50 mg/dL) than model 3 (mean bias = 1.41 and residual error = 4.11 mg/dL), while model 1 was the least accurate (mean bias = 6.94 mg/dL) and the least precise (residual error = 5.40 mg/dL). They were not robust, because they were influenced by almost all the variables studied. The three models for predicting milk urea nitrogen were different with respect to accuracy, precision and robustness.

Nutrients balances and milk fatty acid profile of mid lactation dairy cows supplemented with monensin

The aim of this study was to evaluate the nutrients balance and milk fatty acids profile of dairy cows supplemented with monensin. Twelve Brazilian Holstein dairy cows were distributed into four balanced 3x3 Latin squares, and fed with the following diets: control (C), basal diet without addition of monensin, monensin 24 (M24), addition of 24mg/kg DM of monensin, and monensin 48 (M48), addition of 48mg/kg DM. The experimental diets influenced the efficiency of net energy of lactation utilization. A quadratic effect was observed for the energy balance. It was observed effect of diets on nitrogen balance. It was observed effect of monensin in the milk yield, composition and in the milk fatty acids profile. Monensin in diets of dairy cows in mid lactation, using corn silage, improved the nutrients balance and milk fatty acid profile with 24mg/kg DM.

Submandibular glands and the regulation of gastric proliferation and TGFα distribution during rat postnatal development

Rodent gastric mucosa grows and differentiates during suckling-weaning transition. Among the molecules in rat milk, EGF and TGFβ are important peptides in the control of cell proliferation, and together with TGFα, they are also produced by submandibular glands. We aimed to determine the effect of saliva and milk on epithelial cell proliferation in the stomach of rat pups. We also examined the distribution of TGFα in the gastric mucosa after sialoadenectomy (SIALO) and fasting in order to determine whether this growth factor is affected by the deprivation of molecules derived from saliva and milk. SIALO was performed at 14 days and fasting was induced 3 days later. Cell proliferation was evaluated through metaphasic index and TGFα was detected by immunohistochemistry. We observed that whereas SIALO did not alter cell division, since the metaphasic index (MI) was unchanged, fasting stimulated cell proliferation (P < 0.05). After SIALO and fasting, MI was reduced when compared to the fasted group (P < 0.05). We found that TGFα is distributed along gastric gland and SIALO did not interfere in the localization and number of immunolabeled cells, but fasting increased their density when compared to the control (P < 0.05). The association of SIALO and fasting reduced TGFα immunostaining (P < 0.05). Therefore, during fasting, high MI was parallel to increased TGFα in gastric epithelium, but interestingly, this effect was found only in the presence of submandibular glands. We suggest that during suckling, peptides derived from saliva and milk are important to regulate gastric growth.

Detection of larvae of Toxocara canis in milk: an experimental study in rabbits.

Toxocariasis, caused most commonly by Toxocara canis, is an important cosmopolitan zoonosis. Paratenic hosts have been employed to provide knowledge regard to the transmission of toxocariasis. Transmammary transmission in murine experimentally infected was observed based on the recovery of larvae from the tissue. The aim of this study was to evaluate the possibility of transmammary transmission of Toxocara canis in rabbits by detecting larvae directly in milk. Seventeen sexually mature virgin white New Zealand female rabbits were divided into two groups. Twelve animals were orally inoculated with 1,000 T. canis embryonated eggs (infected group), and five animals remained uninfected (control group). One month following the infection, the females were mated. Manual collection of 500 ?L of milk from each rabbit was performed on days +7, +14 and +21 of lactation for three consecutive lactations. The recovery of larvae was determined via a centrifuge-sedimentation technique using ether and formalin solutions. ELISA test was run to confirm the production of anti-T. canis antibodies (IgG) by infected rabbits. The presence of larvae was observed in milk samples from 5 (41.7%) of the 12 infected rabbits. The total number of recovered larvae was 20, ranging from 1 to 4 larvae per lactation/rabbit. Larvae were recovered exclusively on days 7 and 14 of lactation. Recovery was verified in different lactations. No significant difference was observed with respect to the number of larvae either in the same lactation period or in different lactation periods. Anti-T. canis antibodies were detected in all infected rabbits. In conclusion, the presence of larvae in rabbit milk samples suggests the possibility of galactogenic transmission of T. canis in paratenic hosts. Moreover, the technique employed in this study allows for the recovery of larvae directly from milk.

Milk and dairy products: evaluation of bioactive components by analytical techniques

Milk and dairy products are important source of bioactive compounds useful to satisfy the nutritional and physiological needs of any newborns of mammalian species and useful to guarantee adequate growth and development of infants as well as provide a complete nourishment of adults. Physico-chemical, nutritional and organoleptic properties of the main constituents and the “minor” components have a crucial role in the quality of milk and milk products. Although in the past decades dietary milk fat was often regarded as harmful for the human health, recent researches suggest that milk contains specific fatty acids with nutritional and physiological health benefits. For these reasons, a major attention is given to the quantity and quality of total fat intake. In the recent years, as a result of the new concept of multifunctional agriculture and the changing behaviours about diet, consumer demands in favor of high-quality, security and safety dairy products are increased. Moreover, milk proteins and milk-derived bioactive peptides are recognized to have a high nutritive value, several health-promoting functional activities and excellent technological properties. Accordingly, growing interest in the development of functional dairy products and preparation of infant formulae for babies who cannot be breast-fed, has been give in order to meet the specific consumer’s requests. This manuscript presents the main results obtained during my PhD research aimed to evaluate the main bioactive lipids and proteins in milk and dairy products using innovative analytical techniques. The experimental section of this manuscript is divided in two sections where are reported the main results obtained during my research activities on dairy products and human milks in order to characterize their bioactive compounds for functional food applications.

Selective REM sleep deprivation in narcolepsy

Narcolepsy is characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep abnormalities, including cataplexy. The aim of this study was to assess REM sleep pressure and homeostasis in narcolepsy. Six patients with narcolepsy and six healthy controls underwent a REM sleep deprivation protocol, including one habituation, one baseline, two deprivation nights (D1, D2) and one recovery night. Multiple sleep latency tests (MSLTs) were performed during the day after baseline and after D2. During D1 and D2 REM sleep was prevented by awakening the subjects at the first polysomnographic signs of REM sleep for 2 min. Mean sleep latency and number of sleep-onset REM periods (SOREMs) were determined on all MSLT. More interventions were required to prevent REM sleep in narcoleptics compared with control subjects during D1 (57 ± 16 versus 24 ± 10) and D2 (87 ± 22 versus 35 ± 8, P = 0.004). Interventions increased from D1 to D2 by 46% in controls and by 53% in narcoleptics (P < 0.03). Selective REM sleep deprivation was successful in both controls (mean reduction of REM to 6% of baseline) and narcoleptics (11%). Both groups had a reduction of total sleep time during the deprivation nights (P = 0.03). Neither group had REM sleep rebound in the recovery night. Narcoleptics had, however, an increase in the number of SOREMs on MSLT (P = 0.005). There was no increase in the number of cataplexies after selective REM sleep deprivation. We conclude that: (i) REM sleep pressure is higher in narcoleptics; (ii) REM sleep homeostasis is similar in narcoleptics and controls; (iii) in narcoleptics selective REM sleep deprivation may have an effect on sleep propensity but not on cataplexy.

EEG correlation and power during maintenance of wakefulness test after sleep-deprivation

To investigate whether there are any objective EEG characteristics that change significantly between specific time periods during maintenance of wakefulness test (MWT) and whether such changes are associated with the ability to appropriately communicate sleepiness.