Review of equations to predict methane emissions in dairy cows from milk fatty acid profiles and their application to commercial dairy farms.

Greenhouse gas emission from the activities of all productive sectors is currently a topic of foremost importance. The major contributors in the livestock sector are ruminants, especially dairy cows. This study aimed to evaluate and compare 21 equations for predicting enteric methane emissions (EME) developed on the basis of milk traits and fatty acid profiles, which were selected from 46 retrieved through a literature review. We compiled a reference database of the detailed fatty acid profiles, determined by GC, of 992 lactating cows from 85 herds under 4 different dairy management systems. The cows were classified according to DIM, parity order, and dairy system. This database was the basis on which we estimated EME using the selected equations. The EME traits estimated were methane yield (20.63 ± 2.26 g/kg DMI, 7 equations), methane intensity (16.05 ± 2.76 g/kg of corrected milk, 4 equations), and daily methane production (385.4 ± 68.2 g/d, 10 equations). Methane production was also indirectly calculated by multiplying the daily corrected milk yield by the methane intensity (416.6 ± 134.7 g/d, 4 equations). We also tested for the effects of DIM, parity, and dairy system (as a correction factor) on the estimates. In general, we observed little consistency among the EME estimates obtained from the different equations, with exception of those obtained from meta-analyses of a range of data from different research centers. We found all the EME predictions to be highly affected by the sources of variation included in the statistical model: DIM significantly affected the results of 19 of the 21 equations, and parity order influenced the results of 13. Different patterns were observed for different equations with only some of them in accordance with expectations based on the cow's physiology. Finally, the best predictions of daily methane production were obtained when a measure of milk yield was included in the equation or when the estimate was indirectly calculated from daily milk yield and methane intensity.

Ruminal microbiome changes across lactation in primiparous Holstein cows with varying methane intensity: Heritability assessment.

Methane is a potent greenhouse gas produced during the ruminal fermentation and is associated with a loss of feed energy. Therefore, efforts to reduce methane emissions have been ongoing in the last decades. Methane production is highly influenced by factors such as the ruminal microbiome and host genetics. Previous studies have proposed to use the ruminal microbiome to reduce long-term methane emissions, as ruminal microbiome composition is a moderately heritable trait and genetic improvement accumulates over time. Lactation stage is another important factor that might influence methane production but potential associations with the ruminal microbiome have not been evaluated previously. This study sought to examine the changes in ruminal microbiome over the lactation period of primiparous Holstein cows differing in methane intensity and estimate the heritability of the abundance of relevant microorganisms. Ruminal content samples from 349 primiparous Holstein cows with 14 - 378 d in milk were collected from May 2018 to June 2019. Methane intensity (MI) of each cow was calculated as methane concentration/milk yield. Up to 64 taxonomic features (TF) from 20 phyla had a significant differential abundance between cows with low and high MI early in lactation, 16 TF during mid lactation, and none late in lactation. Taxonomical features within the Firmicutes, Proteobacteria, Melainabacteria, Cyanobacteria, Bacteroidetes and Actinobacteria phyla were associated to low MI, whereas eukaryotic TF and those within the Euryarchaeota, Verrucomicrobia, Kiritimatiellaeota, Lentisphaerae phyla were associated to high MI. Out of the 60 TF that were found to be differentially abundant between early and late lactation in cows with low MI, 56 TF were also significant when cows with low and high MI were compared in the first third of the lactation. In general, microbes associated with low MI were more abundant early in lactation (e.g., Acidaminococcus, Aeromonas and Weimeria genera) and showed low to moderate heritabilities (0.03 to 0.33). These results suggest some potential to modulate the rumen microbiome composition through selective breeding for lower MI. Differences in the ruminal microbiome of cows with extreme MI levels likely result from variations in the ruminal physiology of these cows and were more noticeable early in lactation probably due to important interactions between the host phenotype and environmental factors associated to that period. Our results suggest that the ruminal microbiome evaluated early in lactation may be more precise for MI difference, and hence, this should be considered to optimize sampling periods to establish a reference population in genomic selection scenarios.

Macronutrient content of pasteurised donor human milk: Variability between batches from single-donor pools at an Australian milk bank.

AIM: This study aimed to characterise the between-batch variability of pasteurised donor human milk (PDHM) produced from single-donor pools at Australian Red Cross Lifeblood's milk bank and identify key donor characteristics that predict macronutrient content. METHODS: Macronutrient content from 200 batches of PDHM was measured using a mid-infrared human milk analyser (Miris, Uppsala, Sweden). Linear mixed models were used to study the impact of stage of lactation and gestational age on macronutrient content. Coefficients of determination (R2 ) were calculated to estimate the impact of the individual donor on overall variability. RESULTS: Macronutrient content of PDHM varied considerably, with between-batch variations of 2.8 and 6.4-fold for protein and fat content, respectively. Mean crude protein content was 1.16 g/100 mL, ranging from 0.7 to 1.96 g/100 mL. Mean fat content was 3.85 g/100 mL, ranging from 1.46 to 9.39 g/100 mL. Stage of lactation was identified as a predictor for protein content and gestational age at birth for fat content. Individual donor effect explained 55 and 35% of the variance for fat and protein content, respectively. CONCLUSIONS: This study highlights the variation in macronutrient content in PDHM at an Australian milk bank. Variability could be reduced through the implementation of targeted multiple-donor pooling using the key donor characteristics identified in this study along with the measurement of macronutrient content of individual donors at the time of first donation. However, the clinical benefit of a reduction in between-batch variation, achieved through multiple-donor pooling, would need to be assessed to justify additional efforts associated with PDHM processing changes.

Production performance of Holstein cows at 4 stages of lactation fed 4 dietary crude protein concentrations.

Dairy cow responses to dietary crude protein (CP) may depend on stage of lactation. The primary objective of this study was to evaluate the effects of 4 concentrations of dietary CP on dry matter intake (DMI), production performance, net energy for lactation (NEL) output in milk, feed efficiency (FE: milk NEL/DMI), and nitrogen use efficiency (100 × milk protein-N/N intake) when fed to cows grouped as early, mid-early, mid-late, and late lactation. Our secondary objective was to determine the range of CP concentration at which production responses were not negatively affected across days in milk (DIM). Multiparous Holstein cows (n = 64) were stratified by DIM [initial average ± standard deviation: 86 ± 14.9 (early), 119 ± 10.0 (mid-early), 167 ± 22.2 (mid-late), and 239 ± 11.1 (late)] and then randomly assigned within DIM group to receive 1 of 4 total mixed rations containing 13.6, 15.2, 16.7, and 18.3% CP (dry matter basis) according to a 4 × 4 factorial arrangement of treatments. Cows were individually fed a covariate diet for 14 d, followed by 56 d of treatment diets. Milk yield and DMI were recorded daily and milk components were analyzed weekly for 2 consecutive days at 3 daily milkings. Data were analyzed using a categorical mixed-effect model to evaluate the effects of CP concentration and DIM using linear, quadratic, and cubic contrasts, and their interactions. Additionally, a mixed-effect cubic regression model was fit with DIM, dietary CP concentration, and their interaction as continuous independent variables. Dietary CP concentration deemed optimal across DIM was determined as the range of CP for which the dependent responses did not differ from the predicted maximum. With advancing stage of lactation, DMI, milk NEL output, and FE decreased linearly (from 30.4 to 28.4 kg/d for DMI, from 33.2 to 23.3 Mcal/d for NEL output, and from 1.09 to 0.82 Mcal milk NEL/kg DMI for FE for early and late lactation cows, respectively). Responses to dietary CP concentration were linear, quadratic, and cubic with the greatest values observed when cows were fed the 16.7% CP diet across DIM (30.8 kg/d, 31.0 Mcal/d, and 1.01 Mcal/kg for DMI, milk NEL output, and FE, respectively). There was an interaction between dietary CP concentration and stage of lactation for DMI, milk NEL output, milk component yield, and FE, which was due to the decline in response to additional CP as lactation progressed. Compared with the 16.7% CP diet, feeding the 18.3% CP diet decreased milk NEL 0.81 and 5.3 Mcal/d for early and late lactation cows, respectively, indicating that feeding a higher CP concentration in late lactation had a negative effect on cow performance. Nitrogen use efficiency declined linearly with increasing CP concentration and DIM. Regression analysis suggested that dietary CP ranging from 16.3 to 17.4% maintained production in early and mid-early lactation. However, dietary CP could be reduced to between 15.7 and 17.1% in late lactation. This research suggested that there are distinct ranges of dietary CP concentrations that maintain cow performance at each stage of lactation.

Hematology reference intervals during the prepartum period, first week after calving, and peak lactation in clinically healthy Holstein cows.

Dairy cows face precipitous metabolic adaptations during the first postpartum week. Increasing knowledge of their hematologic profiles during this period could benefit both veterinary clinical pathologists and bovine practitioners. The objectives of this study were: (a) to establish period-specific RIs for Holstein dairy cows and (b) to assess the potential simultaneous effect of several factors on hematology parameters. Blood samples from clinically healthy cows of nine herds were used to establish hematology RIs for these periods. There were 68 cows in the prepartum period (PP), 247 and 218 cows at 2 and 8 days after calving (2 and 8 days in milk [DIM 2 and DIM 8], respectively), and 87 cows in peak lactation (PL). A complete blood count evaluation was performed using the ADVIA 120 analyzer. Linear models estimated the analytes associated with parity. RIs were calculated with Reference Value Advisor. Parity had a significant effect on analytes at all stages. Marked differences were evident between DIM 2 and 8 regarding red blood cell (RBC) counts, hematocrits, hemoglobin concentrations, and white blood cell (WBC), monocyte, and eosinophil counts. Reference intervals of RBC counts, hematocrits, and hemoglobin concentrations at DIM 2 were higher than those at PP and PL. This study provides evidence that period-specific RIs should be used for Holstein cows when making clinical decisions, especially during the critical first week postpartum.

Changes in nutrient balance, methane emissions, physiologic biomarkers, and production performance in goats fed different forage-to-concentrate ratios during lactation.

The objective was to determine the effect forage-to-concentrate (F:C) ratio and stage of lactation on methane emissions, digestibility, nutrient balance, lactation performance, and metabolic responses in lactating goats. Twenty Murciano-Granadina dairy goats were used in an experiment divided into 3 periods: early (30 d), mid (100 d), and late (170 d) lactation. All goats were fed a diet with 35:65 F:C (FCL) during early-lactation. Then, 1 group (n = 10 goats) remained on FCL through mid- and late-lactation while the other group (n = 10 goats) was fed a diet with 50:50 F:C at mid-lactation (FCM) and 65:35 (FCH) at late lactation. A greater proportion of concentrate in the diet was associated with greater overall intake and digestibility (P < 0.05). Energy balance was negative in early-lactation (-77 kJ/kg of BW0.75, on average) and positive for FCL at mid- and late-lactation (13 and 35 kJ/kg of BW0.75, respectively). Goats fed FCM and FCH maintained negative energy balance throughout lactation. Plasma concentrations of non-esterified fatty acids at mid-lactation were greater for FCM than FCL (680 mEq/L), and at late-lactation concentrations were greater for FCH and FCL (856 mEq/L). A similar response was detected for plasma ß-hydroxybutyrate. Methane emission was greater (P < 0.05) for FCM than FCH (1.7 g CH4/d). This study demonstrated that differences in F:C across stages of lactation lead to distinct metabolic responses at the level of the rumen and tissues.

Non-genetic effects on daily milk yield and components of Holstein cows in Morocco.

The objectives of this study were to determine milk yield and constituents' levels of Holstein cows under Moroccan conditions and to assess the effects of environmental factors influencing them. Data including 93,815 test day records of 6343 Holstein cows in 162 herds were analyzed for milk yield, contents of fat, protein, lactose and solids-not-fat (SNF), milk urea nitrogen (MUN), and somatic cell score (SCS). Averages were 25.1 ± 7.33 kg/day, 3.54 ± 0.76%, 3.02 ± 0.34%, 4.89 ± 0.24%, 8.72 ± 0.36%, 17.6 ± 8.17 mg/dl, and 4.12 ± 2.06 units, respectively. The effects of herd and calving year were found to be significant on all the studied traits. Parity was determined to have significant effects on all analyzed traits, with the exception of MUN concentration. Milk yield, fat content, protein content, and SCS increased with parity, whereas lactose percentage decreased in later parities. Except fat and lactose contents, all the other studied variables were significantly influenced by calving season. Milk yield and MUN were highest for cows calving during humid season, whereas protein content, SNF content, and SCS tended to be higher in dry season. All the studied traits changed significantly according to stage of lactation. The peaks of milk yield and lactose content occurred between 35 and 65 days, whereas that of MUN between 95 and 125 days after parturition. Protein and SNF contents and SCS attained their lowest values between days 35 and 65, while fat content between days 65 and 95. It was concluded that these environmental factors should be taken into consideration if the milk yield and quality in Morocco is to be optimized.

Systematic Review of the Literature of Factors Affecting the Exposure and the Levels of Lead in Human Breast Milk.

Human milk may sometimes contain chemical contaminants, which could have adverse effects on neonates or nursing infants. Lead (Pb) is of considerable interest due to its toxicity and occurrence. Furthermore, it has been suggested that human milk is a significant potential source of lead exposure to nursing infants. A systematic literature search in PubMed, Science Direct, and Google Scholar databases was performed to identify relevant studies, published in English until 2017, that investigated and explored common factors affecting the level of lead in human milk among lactating women around the world. Forty-nine papers were rated and explored the effect of one or several factors on the level of lead in human milk from 28 countries and carried out over a wide time frame from 1983 to 2017 and through Europe, Asia, America, and Africa, reviewing more than 5,000 subjects. Place of residence, maternal age, stage of lactation, smoking habits, maternal dietary intakes, and parity were the mostly assessed factors among the studies and considered as the main factors affecting Pb levels in BM. Other factors were not studied well enough and considered minor because few surveys evaluated their impacts. However, the literature findings are very controversial.

Milk composition of Holstein cows: a retrospective study / Caracterização da composição do leite de vacas Holandesas: estudo retrospectivo

ABSTRACT: Worldwide, milk analysis is an satisfactory measurement of milk quality on dairy farms. Milk composition is the base for payment systems, so knowledge of its characteristics at different periods is essential for modern dairy producer. The aim of the study was to evaluate the effects of year, season, stage of lactation, and lactation number on variations in milk yield and composition of Holstein cows (n=148,604). Milk yield estimated by multiple regression was 25,50L/cow/day. Winter was the season with the highest milk yield and the highest protein and lactose content. Milk fat was highest in the fall, in cows in late lactation and also in primiparous cows. Lactating cows from 6 to 60 days in lactation and those in 2nd or 3rd lactation showed the highest milk yield. Lactose concentration was positively correlated with milk yield. Somatic cell score was negatively correlated with milk yield and with lactose concentration. Most important variations in milk characteristics occur among seasons, lactation stages and parities. Mammary gland health is yet the greatest challenge to be overcome.

RESUMO: A determinação da qualidade do leite nas fazendas é um parâmetro mundialmente aceito e utilizado como base para os sistemas de pagamento. Os produtores modernos utilizam o conhecimento das características do leite para adotar medidas que visam melhorar produtividade e qualidade. O objetivo do estudo foi avaliar os efeitos do ano, estação, estágio de lactação e número de lactação sobre as variáveis produção e composição do leite de vacas Holandesas (n=148,604). A produção de leite estimada por regressão múltipla foi de 25,50L/vaca/dia. O inverno foi à estação com a maior produtividade e os maiores teores de proteína e lactose. A gordura de leite foi maior no outono em vacas primíparas e no final da lactação. As vacas com estágio de lactação entre 6 a 60 dias e aquelas que se encontram na segunda ou terceira lactação apresentaram a maior produtividade. A concentração de lactose correlacionou-se positivamente com a produção de leite. O escore das células somáticas correlacionou-se negativamente com a produtividade e com a concentração de lactose. As variações mais importantes nas características do leite ocorrem entre estações, estágios de lactação e número de partos. A saúde da glândula mamária ainda é o maior desafio a superar.

Effect of genetic and nongenetic factors on chemical composition of individual milk samples from dromedary camels (Camelus dromedarius) under intensive management.

The aims of the present study were to monitor the changes in gross chemical composition of individual dromedary camel milk over a 5-yr period, to provide reference values, and to determine the effect of genetic and nongenetic factors influencing camel milk composition under intensive management. A total of 1,528 lactating dromedary camels were included in the study. Animals were fed a constant diet and were milked twice a day in a herringbone parlor. Milk samples were collected at monthly intervals using a sampling device and then fat, protein, lactose, total solids (TS), and solids-nonfat (SNF) concentrations of raw camel milk were determined with an automatic milk analyzer. For each milk sample, production parameters were recorded and quantities (grams) of milk constituents were calculated. The overall mean quantity and fat, protein, lactose, SNF, and TS concentrations of the morning milk were 4.0 kg, 2.58%, 2.95%, 4.19%, 8.08%, and 10.46%, respectively. Milk quantity showed a positive correlation with lactose and a negative correlation with all other components. Parity exerted a strong effect on all milk parameters. Primiparous dromedaries (n = 60) produced less milk with higher concentrations of components than did multiparous animals (n = 1,468). Milk composition varied among the 7 breeds tested, but none of the genotypes was found to be superior to the others in this respect. We detected a significant, yet small calf sex-biased difference in milk yield and composition. Stage of lactation and season strongly influenced milk yield and all milk components. We also found a significant interaction between month postpartum (mPP) and month of the year. The concentration of all milk components decreased from 1 to 5 mPP. Later, lactose concentration and quantity continued to decrease parallel with decreasing milk production. The concentration of other components showed a temporary increase in mid lactation, from 6 to 11 mPP, and in late lactation, from 18 to 23 mPP. Mean fat, protein, SNF, and TS concentrations showed a high seasonal variation (9.5 to 28.7%), with the lowest and highest values being measured during summer and winter, respectively. This seasonal variation was independent of nutrition and may reflect an endogenous circannual rhythm. We observed a noticeable variation among years. Dromedary camels could provide a useful in vivo model to study the homeorhetic regulation of mammary cell function by endogenous and environmental factors.

Minerals and Trace Elements in Human Breast Milk Are Associated with Guatemalan Infant Anthropometric Outcomes within the First 6 Months.

BACKGROUND: Breast milk is the recommended source of nutrients for infant growth, but its adequacy to meet infants' mineral and trace element needs is unknown. OBJECTIVES: We used breast-milk mineral and trace element concentrations of Guatemalan mothers at 3 lactation stages to estimate total daily intakes and to determine whether intakes were associated with early infant growth. METHODS: In this cross-sectional study, breast-milk samples were collected from Mam-Mayan mothers during transitional (5-17 d, n = 56), early (18-46 d, n = 75), and established (4-6 mo, n = 103) lactation; z scores for weight (WAZ), length (LAZ), and head circumference (HCAZ) were measured. Concentrations of 11 minerals (calcium, potassium, magnesium, sodium, copper, iron, manganese, rubidium, selenium, strontium, and zinc) were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). WHO equations were used to calculate the estimated energy requirement, which was divided by the energy density of breast milk to estimate daily milk volume, and this number was multiplied by breast-milk mineral concentrations to estimate intakes. Principal component analyses identified clusters of minerals; principal components (PCs) were used in regression analyses for anthropometric outcomes. RESULTS: Estimated breast-milk intakes during established lactation were insufficient to compensate for the lower milk sodium, copper, manganese, and zinc concentrations in male infants and the lower sodium, iron and manganese concentrations in female infants. Estimated intakes of calcium, magnesium, potassium, sodium, and selenium were below the Institute of Medicine Adequate Intake for both sexes at all 3 stages of lactation. In early lactation, multiple linear regressions showed that PC1 (calcium, magnesium, potassium, rubidium, and strontium intakes) was positively associated with WAZ, LAZ, and HCAZ. In established lactation, the same PC with sodium added was positively associated with all 3 anthropometric outcomes; a second PC (PC2: zinc, copper, and selenium intakes) was associated with WAZ and LAZ but not HCAZ. CONCLUSIONS: Breast milk may be inadequate in selected minerals and trace elements where higher estimated intakes were associated with greater infant growth.

Effect of stage of lactation on the immune competence of goat mammary gland.

The present research was undertaken to evaluate the effect of stage of lactation on immune competence of the goat mammary gland. The prevalence and etiology of intramammary infections and cytokine pattern were studied in individual caprine milk during lactation. A total of 1,200 caprine milk samples were collected during early, mid, and late lactation (less than 40 d, from 110 to 130 d, and more than 200 d in lactation, respectively) and analyzed for milk quality, bacterial cell load, and cytokine pattern. Contagious and environmental pathogens associated with intramammary infection were isolated from caprine milk. Nutritional components of caprine milk were affected by stage of lactation; fat, protein, casein, and whey protein increased along with lactation due to the lowest milk yield. Lactose content showed an opposite trend, with a reduced percentage passing from early to late lactation. The impaired rheological properties detected in early and late lactation milk were associated with a modification of milk quality. An impairment of microbial quality was detected at the end of lactation as a consequence of a major susceptibility of mammary gland to infections. The percentage of bacteriologically positive caprine milk samples was 44% throughout lactation. The incidence of bacteria associated with intramammary infection was different according to the stage of lactation with a major prevalence of Staphylococcus aureus, Enterobacteriaceae, Staphylococcus hyicus, and Streptococcus uberis in early lactation milk, Staphylococcus chromogenes, Streptococcus bovis, and Staphylococcus epidermidis in mid lactation, and Pseudomonas aeruginosa and Staphylococcus caprae in late lactation milk. The higher values of IL-1ß, tumor necrosis factor-α, and IL-6 were ascribed to the major prevalence of Staphylococcus aureus at the beginning of lactation, whereas a higher level of IL-10 was detected in mid-lactation caprine milk and correlated with Staphylococcus chromogenes. Monitoring the cytokine pattern in milk helps to understand the immune status of the mammary gland, its ability to cope with bacteria, and the evolution of infections.

Influence of stage of lactation and year season on composition of mares' colostrum and milk and method and time of storage on vitamin C content in mares' milk.

BACKGROUND: Mares' milk is becoming increasingly popular in Western Europe. This study was thus aimed at investigating the impact of stage of lactation and season on chemical composition, somatic cell count and some physicochemical parameters of mares' colostrum and milk, and at developing a method for the determination of vitamin C (ascorbic acid) in mares' milk and to determine its content in fresh and stored milk. RESULTS: The analysis conducted showed an effect of the stage of lactation on contents of selected chemical components and physicochemical parameters of mares' milk. In successive lactation periods levels of fat, cholesterol, energy value, citric acid and titratable acidity decreased, whereas levels of lactose and vitamin C, as well as the freezing point, increased. Analysis showed that milk produced in autumn (September, October, November) had a higher freezing point and lower concentrations of total solids, protein, fat, cholesterol, citric acid and energy value in comparison to milk produced in summer (June, July, August). Mares' milk was characterised by low somatic cell count throughout lactation. In terms of vitamin C stability the most advantageous method of milk storage was 6-month storage of lyophilised milk. CONCLUSION: In general, the results confirmed that mares' milk is a raw material with a unique chemical composition different from that produced by other farm animals.

Perfil bioquímico, inclusive proteinograma, do soro lácteo de búfalas primíparas e pluríparas sadias ao longo da lactação / Biochemical profile, including protein concentration, of whey from healthy primiparous and pluriparous buffaloes during lactation

Para avaliar o perfil bioquímico, inclusive proteínas, do soro lácteo de búfalas Murrah primíparas e pluríparas sadias foram analisadas amostras de leite de 30 fêmeas bubalinas durante uma lactação completa. Os animais foram distribuídos em três grupos: G1 - 10 búfalas primíparas, G2 - 10 búfalas pluríparas com duas a três lactações e G3 - 10 búfalas pluríparas com mais de três lactações. O período de lactação foi dividido em: fase inicial (I: primeiro ao terceiro mês de lactação), fase intermediária (T: quarto ao sexto mês de lactação) e fase final (F: sétimo ao nono mês de lactação). Antes da colheita das amostras de leite foram realizados o exame físico da glândula mamária, o teste da caneca de fundo escuro e o California Mastitis Test (CMT). Após a assepsia dos quartos mamários, foram colhidas mensalmente, durante uma lactação completa, amostras de 20mL de leite de cada quarto mamário, em frascos plásticos esterilizados e sem conservante, para a realização do isolamento microbiológico, determinação do perfil bioquímico e fracionamento proteico por meio de eletroforese em gel de poliacrilamida contendo dodecil sulfato de sódio (SDS-PAGE), e amostras de 30mL de leite de cada quarto mamário, em frascos plásticos esterilizados contendo conservante bronopol, para contagem de células somáticas (CCS). Das 1.042 amostras de leite colhidas dos três grupos experimentais durante a lactação, 923 amostras de leite apresentaram reação negativa ao CMT e isolamento microbiológico negativo e foram selecionadas para as análises do perfil bioquímico e fracionamento proteico em SDS-PAGE. Notou-se influência da ordem de parto e da fase da lactação no perfil bioquímico e no proteinograma do soro lácteo de búfalas da raça Murrah sadias. As búfalas primíparas (G1) apresentaram maior atividade das enzimas gamaglutamiltransferase (GGT: 2.346U/L) e fosfatase alcalina (ALP: 181U/L) e maiores concentrações de fósforo (P: 56,6mg/dL), potássio (K: 32,0mg/dL) e α-lactoalbumina (458mg/dL). As fêmeas com duas a três lactações (G2) apresentaram maior CCS (70.700 células/mL) e maiores concentrações de proteína total (1,55g/dL), albumina (100mg/dL), magnésio (Mg: 8,80mg/dL), cloretos (Cl: 176mg/dL), ferro (Fe: 10,7µg/dL), sódio (Na: 178mMol/L) e lactoferrina (59,5mg/dL). As fêmeas com mais de três lactações (G3) apresentaram maiores concentrações de cálcio total (Ca: 41,8mg/dL), cálcio ionizado (Cai: 2,92mMol/L), imunoglobulina A (IgA: 1,32mg/dL), albumina sérica (99,1mg/dL), imunoglobulina G (IgG: 49,7mg/dL) e b-lactoglobulina (1.068mg/dL). Durante a lactação foi observado aumento da CCS, aumento das atividades das enzimas GGT e ALP, aumento das concentrações de proteína total, albumina, P, Mg, Cl, Na, lactoferrina, albumina sérica, IgG, α-lactoalbumina e redução das concentrações de Ca, Fe, Cai, K, IgA e b-lactoglobulina no soro lácteo das búfalas. Os resultados obtidos podem ser utilizados como referências para a espécie bubalina e auxiliar no diagnóstico e no prognóstico de doenças de ocorrência comum na fase de lactação.(AU)

To evaluate the biochemical profile and protein concentration of whey from milk samples of healthy Murrah primiparous and pluriparous buffaloes, 30 female buffaloes were analyzed during a complete lactation. The animals were divided into three groups: G1 = 10 primiparous buffaloes, G2 = 10 pluriparous buffaloes with 2-3 lactations and G3 = 10 pluriparous buffaloes with >3 lactations. The lactation period was divided into: early stage (I: 1-3 months of lactation), intermediate stage (T: 4-6 months of lactation) and final stage (F: 7-9 months of lactation). Before milk sampling, physical examination of the mammary gland, strip cup test and California Mastitis Test (CMT) were performed. After mammary quarters asepsis, 20mL of milk were collected monthly from each mammary quarter, during a complete lactation, in sterilized plastic bottles without preservative, in order to perform microbiological isolation, biochemical profile and protein electrophoresis in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and 30mL of milk from each mammary quarter were collect, in sterilized plastic bottles containing preservative bronopol to perform the somatic cell count (SCC). A total of 1,042 milk samples were collected from the experimental groups during lactation, of which 923 samples showed negative reaction to CMT and negative microbiological isolation and were selected to biochemical profile analysis and protein electrophoresis in SDS-PAGE. There were influence of parity order and stage of lactation in biochemical profile and protein concentration of healthy Murrah buffaloes' whey. Primiparous buffaloes (G1) showed higher gamma-glutamyltransferase (GGT: 2,346 U/L), alkaline phosphatase (ALP: 181 U/L), phosphorus (P; 56.6mg/dL), potassium (K; 32.0mg/dL) and α-lactalbumin (458mg/dL). Buffaloes with 2-3 lactations (G2) showed higher SCC (70,700 cells/mL) and higher concentrations of total protein (1.55g/dL), albumin (100mg/dL), magnesium (Mg; 8.80mg/dL), chlorides (Cl; 176mg/dL), iron (Fe; 10.7µg/dL), sodium (Na; 178mMol/L) and lactoferrin (59.5mg/dL). Bufalloes with >3 lactations (G3) showed higher concentrations of total calcium (Ca; 41.8mg/dL), ionized calcium (iCa; 2.92mMol/L), immunoglobulin A (IgA; 1.32mg/dL), serum albumin (99.1mg/dL), immunoglobulin G (IgG; 49.7mg/dL) and ß-lactoglobulin (1,068mg/dL). During lactation it was observed increase in SCC, GGT, ALP, total protein, albumin, P, Mg, Cl, Na, lactoferrin, serum albumin, IgG and α-lactalbumin, as well as decrease in concentrations of Ca, Fe, iCa, K, IgA and ß-lactoglobulin in buffaloes' whey. The results may be used as reference for buffaloes and to support diagnosis and prognosis of diseases common to lactation periods.(AU)

Effects of genetic type, stage of lactation, and ripening time on Caciocavallo cheese proteolysis.

The objective of this experiment was to evaluate the effects of genetic type, stage of lactation, and ripening time on proteolysis in Caciocavallo cheese. One hundred twenty Caciocavallo cheeses made from the milk of 2 breeds, Italian Brown and Italian Holstein and characterized by different stages of lactation were obtained and ripened for 1, 30, 60, 90, and 150d. Cheese proteolysis was investigated by ripening index (ratio of water-soluble N at pH 4.6 to total protein, %) and by the study of degradation of the protein fractions (αS1-, ß-, and para-κ-casein), which was determined by densitometric analysis of isoelectric focusing results. The statistical analysis showed a significant effect of the studied factors. Ripening index was higher in Italian Brown Caciocavallo cheese and in cheeses made with early lactation milk, whereas casein solubilization was greater in the first 2mo of ripening. Isoelectric focusing analysis of cheese samples during ripening showed extensive hydrolysis of caseins. In particular, the protein fraction that underwent major degradation by proteolytic enzymes was αS1-casein, followed by ß-casein, whereas para-κ-casein was less degraded. Italian Brown cheese showed a lower residual quantity of ß- and para-κ-casein, whereas Italian Holstein cheese showed a lower residual quantity of αS1-casein. In addition, significant interactions of both first and second order were found on both ripening index and degradation of protein fractions. This study demonstrated that the analyzed factors influenced proteolysis of Caciocavallo cheese, which forms the basis of new knowledge that could lead to the production of a pasta filata cheese with specific characteristics.