Milk Composition Research Articles

Associations between SARS-CoV-2 Infection or COVID-19 Vaccination and Human Milk Composition: A Multi-Omics Approach

BackgroundThe risk of contracting SARS-CoV-2 via human milk-feeding is virtually non-existent. Adverse effects of COVID-19 vaccination for lactating individuals are not different from the general population, and no evidence has been found that their infants exhibit adverse effects. Yet, there remains substantial hesitation among this population globally regarding the safety of these vaccines. ObjectiveHerein we aimed to determine if compositional changes in milk occur following infection or vaccination, including any evidence of vaccine components. Methods and ResultsUsing a subset of milk samples obtained as part of our broad studies examining the effects on milk of SARS-CoV-2 infection and COVID-19 vaccination, an extensive multi-omics approach, we found that compared to unvaccinated individuals SARS-CoV-2 infection was associated with significant compositional differences in 67 proteins, 385 lipids, and 13 metabolites. In contrast, COVID-19 vaccination was not associated with any changes in lipids or metabolites, although it was associated with changes in 13 or fewer proteins. Compositional changes in milk differed by vaccine. Changes following vaccination were greatest after 1-6 hours for the mRNA-based Moderna vaccine (8 changed proteins), 3 days for the mRNA-based Pfizer (4 changed proteins), and adenovirus-based Johnson and Johnson (13 changed proteins) vaccines. Proteins that changed after both natural infection and Johnson and Johnson vaccine were associated mainly with systemic inflammatory responses. In addition, no vaccine components were detected in any milk sample. ConclusionsTogether, our data provide evidence of only minimal changes in milk composition due to COVID-19 vaccination, with much greater changes after natural SARS-CoV-2 infection.

Effect of temporal water restrictions on drinking behavior and time budget in lactating dairy cows according to their position in the social hierarchy within the herd

On dairy farms, milking practices can temporarily restrict cows from accessing drinking water. This study examined how different types of temporary water restriction, similar to those commonly encountered on farms, may affect the individual behavior and physiological dehydration status of cows and whether these effects could differ according to the cow's position in the social hierarchy of the group. Four treatments were applied (CTRL = free access to the drinker and feed fence, HL = 2 h of headlock at the feed fence after morning and evening milking, D2H = free access to the feed fence and no access to water for 2 h after milking and D4H = free access to the feed fence and no access to water for 4 h after milking) to 4 groups of 10 lactating dairy cows using a 4 × 4 Latin square design. Each treatment period lasted 1 week. The cows were housed within a free-stall barn, and each group was in a pen equipped with 1 electronic drinker, 10 individual feeders, and 2 cameras. Cow social dominance hierarchies were characterized using normalized David's scores, which were calculated from video-detected replacements at each pen's drinker. During the last 4 d of each treatment period, drinking behavior was measured using interconnected drinkers, and eating, idle, and lying times were measured using accelerometers. On d 6 of each treatment period, during the morning and evening milkings, blood and then milk samples were collected to analyze bioindicators of dehydration and milk composition, respectively. The daily water intake of cows was unaffected by either social dominance or treatment type. Drinking rate and drinking bout frequency were higher during the HL, D2H, and D4H treatments than during the CTRL treatment, and drinking time was lower during the D4H treatment than during the CTRL treatment. Hourly lying time decreased at the end of the water restriction periods, i.e., at 1000 h in HL, at 1100 h in D2H, and at 1200 and 1300 h in D4H, which was not observed in CTRL, which could be interpreted as a sign of cow discomfort. For blood collected before the morning milking, hematocrit levels were lower in the D4H treatment than in the HL treatment. For blood collected before the evening milking, creatinine concentrations were lower in the D4H treatment than in the D2H treatment, with a greater difference seen for dominant cows than for subordinate cows. For both milkings, milk freezing point was higher in the HL, D2H, and D4H treatments than in the CTRL treatment, indicating dilution. In contrast to the other social categories, subordinate cows made more daily visits to the drinker during the D4H treatment than during the CTRL treatment but displayed no differences in drinking bout duration or the duration of drinking interruptions within bouts in the D2H treatment compared with the CTRL treatment. Overall, cows were able to maintain their water intake despite the temporary water restrictions when they had access to the number of drinkers recommended by animal welfare guidelines. That said, their idle and lying time appeared to be disturbed.

Donor Milk Expression Habits: Can we Favor Hindmilk Banking for Extremely Preterm Infants?

Background: Extremely preterm infants often receive donor milk. Hindmilk, which is released more than 3 minutes after letdown, could be advantageous due to its elevated levels of fat and calorie density. Donor milk expression habits may influence milk composition but have not yet been investigated. This study aims to assess the practices of milk donors and the feasibility of hindmilk expression. Methods: Active milk donors in Québec were questioned using an online survey about their milk expression habits and whether hindmilk donation would be acceptable to them. Answers were analyzed using mixed methods. Results: Of 181 donors, 126 fully completed the questionnaire (70%); 57% reported expressing donated milk between breastfeeds; 15% reported simultaneously breastfeeding while expressing donated milk from the other breast; 12% reported breastfeeding their baby on each breast, then expressing donated milk (hindmilk). The majority (66%) would be willing to change their habits most or all the time to provide hindmilk for preterm infants. The main themes invoked by respondents in open-ended answers were altruism and gratitude for being able to help others. However, 15% commented on the complexity of milk expression or that adding further complexity might discourage them from donating. Conclusions: Expression practices are variable, which may lead to variability in donor milk composition. Most donors would agree to change their expression habits in favor of giving hindmilk to help the most fragile infants. More information is needed on how changing recommendations for milk expression might impact the supply and composition of donor milk.

Assessment of mammary stress in early lactating crossbred (Alpine × Beetal) does during heat stress in conjunction with milk somatic cells and non-invasive indicators

Milk somatic cell counts (SCC) are crucial for monitoring dairy animals' mammary health and milk quality. This study was initiated to assess the mammary health of early lactating crossbred (Alpine × Beetal) does during periods of heat stress. The udder skin surface temperature (USST), total and differential milk SCC, milk composition, milk cortisol levels and phagocytic activity (PA) of milk neutrophils and macrophages were estimated in these does. Results indicated a significant (p<0.01) increase in the milk neutrophils to macrophages (N: M) ratio and milk cortisol levels with milk somatic cell score (SCS). The PA of milk neutrophils decreased significantly (p<0.01), while that of macrophages increased significantly (p<0.01) with higher SCC. On Pearson correlation, milk SCS revealed strong positive correlation (p<0.01) with N: M ratio (r=0.90), USST (r=0.98), milk cortisol (r=0.97), milk pH (r=0.83) and conductivity (r=0.92). Conversely, milk lactose exhibited a moderate negative correlation of (r= −0.48) with SCS. These findings suggest that USST infrared thermography and milk cortisol levels are promising non-invasive methods for rapidly assessing mammary stress in early lactating does during heat stress.

Carbohydrate composition of cow's milk and plant-based milk alternatives

The prevalence of lactose intolerance is one of the factors driving consumers toward plant-based milk alternatives (PBMA). This study aimed to analyze the carbohydrate profile of cows' milk (regular and lactose-free from both pasteurized and UHT milks; n = 80) and PBMA (n = 60) by HPLC. The study revealed that there was no significant difference in the energy content and total carbohydrate content between regular milk and lactose-free milk. Although milk and PBMA are entirely different food matrices, some PBMA types, as soya and coconut, may have energy contents and total carbohydrate contents comparable to those of milk. Furthermore, the variability observed in total carbohydrate content, as well as in carbohydrate profile, both between PBMA types and within samples of the same type, arises not only from variations in raw materials but also from the number of dilutions of the vegetable extract and the addition of different types and levels of carbohydrates, such as sucrose, fructose, or sorbitol, during PBMA manufacture. Although, milk presents a regular carbohydrate composition, differing solely between presentations (regular/lactose-free), the PBMA differs significantly between types and among the same type, not being for that reason regarded as a milk substitute.

Milk metabolite composition of a semi-captive population of Asian elephants.

Lack of maternal milk commonly leads to Asian elephant calves' death in captivity. Currently, available supplements seem inefficient. Hence, we aimed at characterizing the composition of Asian elephant milk to provide information on calves' nutritional needs. Seventy milk samples from 22 Asian elephants living in semi-captivity in their natural environment in Myanmar were collected. Samples were analysed through various techniques including liquid chromatography tandem mass spectrometry, gas chromatography-flame ionization detector, and bicinchoninic acid assay to determine total protein content and various metabolites. Associations with lactation stage (months postpartum) were investigated through repeated measure mixed models. We identified 160 compounds: 22 amino acids, 12 organic acids of the tricarboxylic acid cycle, 27 fatty acids, 15 acyl-carnitines and 84 phospholipids. The milk contained substantial amounts of free glutamate (median: 1727.9, interquartile range (IQR): 1278.4 µmol l-1) and free glycine (2541.7, IQR: 1704.1 µmol l-1). The fatty acid profile was mostly constituted by saturated fatty acids, particularly capric acid (40.1, IQR: 67.3 g l-1). Milk samples also contained high amounts of carnitines, phospholipids and organic acids. The wide array of metabolites identified and quantified, some of which present high concentrations in the milk from this species as opposed to other species, suggests underpinning physiological functions that might be crucial for the survival of Asian elephant calves.

Objectives for the use of raw materials and component composition for the production of low-lactose ice cream from goat milk

A huge number of people all over the world suffer from lactose intolerance. The second problem is an allergy to cow milk protein. People with lactose intolerance, as well as those who suffer from cow milk allergies, are forced to significantly limit their choice of ice cream or give it up completely. The article describes a solution to the problem of eating ice cream by children and adults suffering from lactose intolerance and an allergy to cow milk protein, and presents ways to overcome it.The goal of the research. Objectives for the use of raw materials and component composition for the production of low-lactose ice cream from goat milk. During the research, the quality indicators of the selected raw materials have been studied, the characteristics of the main ingredients for the production of low-lactose ice cream have been substantiated and given. Goat milk, in terms of its quality indicators, is most suitable for the production of ice cream, because it contains more protein, fat, solids, less lactose and does not cause allergies, and therefore it has been chosen as the main raw material for the production of ice cream. A theoretical and practical analysis of the chemical composition and properties of goat milk has been carried out, and compared with cow. To reduce the lactose content, a dual method of lactose hydrolysis has been chosen - the use of probiotic starter cultures and the lactase enzyme. In the process of combined hydrolysis at a temperature of 37-39⁰ C for 4-6 hours, a reduction in lactose content of less than 0.9% is achieved, while the concentration of cells of probiotic microorganisms in active form reaches 108 CFU/cm3. It is proposed to use the “Lactomix KM” stabilization system, which is usually used in the production of fermented milk products.

Concentrations and predictors of select nutrients in Canadian human milk samples from the Maternal-Infant Research on Environmental Chemicals pregnancy cohort

BackgroundHuman milk (HM) composition data are widely used in clinical, regulatory, and public health initiatives. The existing HM profiles in United States and Canadian nutrient databanks are outdated and now considered inappropriate to estimate current nutrient intakes. Recent reviews have underscored the limited North American data available to generate a new profile. ObjectivesTo describe concentrations and sources of variability of nutrients in HM from a large cohort collected in Canada. MethodsThe Maternal-Infant Research on Environmental Chemicals (MIREC) study recruited participants in the first trimester of pregnancy from 10 Canadian cities between 2008 and 2011. HM samples (n = 559–835, depending on nutrient) were collected 3–10 wk postpartum and analyzed for minerals (calcium, magnesium, phosphorus, potassium, sodium, manganese, molybdenum, zinc, copper, iodine, selenium), vitamin D [vitamin D3, 25-hydroxyvitamin D3], folate vitamers (folic acid, 5-methyltetrahydrofolate, total folates), and fatty acids (panel). We examined associations between participant characteristics and log-transformed nutrient concentrations using linear regression. ResultsConcentrations of HM components in MIREC samples were within the range observed in literature except for manganese, which was >100-fold lower than the value in the existing Canadian nutrient databank profile [2.43 (standard deviation 2.84) compared with 260 ng/g]. In multivariable models, concentrations of folate vitamers, vitamin D, and fatty acids demonstrated greater variability with maternal and sample characteristics than minerals. Factors such as relevant supplement use, body mass index, and for vitamin D, skin color and season, had a larger impact on nutrient concentrations than characteristics typically standardized in HM research, such as maternal or infant health, and method of collection. ConclusionsHM mineral concentrations from this study meet the methodological inclusion criteria for updating nutrient databank values and dietary reference intakes. Consideration of factors such as diet, skin color, and BMI will be important for selecting studies for developing representative reference values based on HM.

Impact of Management and Nutrition on HSP70 Gene Expression in Heat-stressed Dairy Cows

Background: This research investigated the effects of management and nutrition strategies on dairy cows under heat stress. Objectives: We aimed to evaluate the effects of zinc mineral supplementation and mist spray, alone and in combination, on yield, milk production and composition, blood parameters and HSP70 gene expression in dairy cows. Methods: Sixteen Holstein lactating cows were used for our experiment in four treatment groups: Basal diet without heat stress alleviation methods (control), zinc supplementation in diet, basal diet and application of mist spray method and supplementation of zinc in basal diet with mist spray. We measured milk production and composition, blood parameters and HSP70 gene expression in all cows. Results: The results showed that the cows in the mist and zinc+mist treatments had significantly better performance and temperature-humidity index than the control group. The milk yield and its compounds were significantly affected by experimental treatments, with the best results seen in the treatment with both spray and zinc. The cows exposed to dry and lactation periods showed a significant increase in the concentration of blood biochemical factors and antioxidant indices in response to heat stress. HSP70 gene expression was significantly decreased in all treatments compared to the control. Conclusion: This experiment suggests that applying nutritional and management strategies can effectively mitigate the effects of heat stress on dairy cows. The study recommends using zinc supplementation and mist spray to alleviate heat stress effectively. Overall, this study highlights the importance of implementing management and nutrition strategies to improve the welfare and productivity of dairy cows under heat stress.

Addition of selenium nanoscale to high diets with wheat bran and its effect on milk production and composition in Awassi ewes

Addition of selenium nanoscale to high diets with wheat bran and its effect on milk production and composition in Awassi ewes

Does the Composition of Breast Milk in the First Week Postpartum Differ Due to Maternal Factors or Neonatal Birth Weight and Percent Fat Body Mass?

Background: The composition of breast milk is dependent on numerous factors. However, the precise impact of maternal health conditions on breast milk composition remains to be fully elucidated. Similarly, there is a paucity of evidence regarding the correlation between neonatal body composition and human milk. The objective of the study was to evaluate the macronutrient composition of breast milk collected during the first week postpartum from mothers with gestational diabetes and healthy mothers in terms of selected maternal and neonatal factors. Methods: n = 70 breast milk samples were analyzed for fat, protein, carbohydrate, dry matter, true protein, and energy. The results were evaluated in terms of selected maternal factors, as well as neonatal birth weight (BW) and percent fat body mass (%FBM), which was assessed with a bioimpedance method. Results: Energy of breast milk in the study group was as follows: median 55.5 kcal/dL in GDM G1, median 55.5 kcal/dL in GDM G2, and median 65.0 kcal/dL in non-GDM, which differed significantly in Kruskal–Wallis ANOVA. Neonatal %FBM, but not BW, was found to be significantly related to concentrations of protein, true protein and dry matter. Maternal gestational weight gain, history of hypothyroidism, and classification by study group were identified as factors affecting both breast milk and neonatal body composition. Conclusions: The composition of breast milk in the initial week following childbirth is predominantly determined by maternal factors. The relationship between selected macronutrients and neonatal percent fat body mass was found to be weak, yet the significance of this finding is unclear. Further research is required to ascertain the influence of maternal milk composition on early infantile nutritional programming.

Effects of seasonal factors on the milk composition of dairy cows in Tafawa Balewa L.G.A, Bauchi State

This study compared the nutrient composition of milk between cattle breeds of Bunaji, Rahaji, Sokoto gudali and Adamawa gudali for both rainy and dry season. One hundred questionnaires were administered to respondents and 5% had milk yield of 3litre/day. 55% recorded 2 litre/day of milk while 40% had the least yield of 1litre/day. That early lactation produces highest milk quantity. The result of laboratory analysis showed that season have effect on nutrient composition of cow milk. It was observed that the early dry season milk composition was better for Bunaji, Rahaji, Sokoto gudali except for Adamawa gudali. For rainy season comparison, early rainy season milk composition was better for Bunaji, Sokoto gudali, Adamawa gudali except for Rahaji. Moisture content in dry season (70.08%) was lower (P&gt;0.05) than moisture content in rainy season (87.36%) for Bunaji breed, similar result was obtained for Rahaji, Sokoto gudali and Adamawa gudali. The energy content and carbohydrate were higher (P&lt;0.05) in the dry season for Bunaji(132.15KCal and 14.06%), Rahaji (126.20KCal and 14.55%), Sokoto gudali (148.00KCal and 22.05%) and Adamawa gudali (135.18KCal and 20.99%). The crude protein of analysed milk was slightly higher (P&lt;0.05) in rainy season for Bunaji (5.64%), but higher in dry season for Rahaji (5.48%), Sokoto gudali (7.47%) and Adamawa gudali (6.01%). ether extract were all higher in dry season for breeds except Sokoto gudali. crude fibre was higher (5.34% Bunaji, 5.28% Rahaji, 3.45% S. gudali, 4.04% A. gudali) in dry season for all breed. Milk in all the four breeds of cattle have more of the nutrient composition in dry season at a higher level. Seasonal variation and climatic factors like rain, humidity and wind affects milk composition and cattle production in terms of pasture availability and the quality. The herders need to be encouraged to engaged in modern way of herding by possessing land for farming, they can rent it in exchange of crop residues and they can cultivate their personal farm produce and faster yielding pasture can be cultivated.

Dietary inclusion of white lupine seeds and their byproducts in rabbits can contribute to EU agricultural sustainability: a review

This review explores the potential of white lupin seeds (Lupinus albus) as a sustainable protein source for rabbit nutrition and examines their effects on growth performance, carcass traits, health status, milk yield, milk composition and nutrient availability. The dietary inclusion of white lupin seeds leads to comparable or superior growth, milk yield, milk composition, nutrient digestibility and digestive health of rabbits, as well as meat quality and carcass outcomes relative to traditionally used protein sources for feeding rabbits, such as soybean meal and sunflower meal. Studies also show that it is possible to use white lupin byproducts, such as the hull and bran, for rabbit diets, which can be convenient in terms of providing an adequate supply of lignocellulose and enhancing the sustainability of rabbit feed, promoting circular economy principles. The cultivation of white lupin can contribute to environmental sustainability by reducing greenhouse gas emissions and the use of synthetic fertiliser. Future research should focus on breeding improvements and comprehensive environmental assessments of white lupin seeds to maximise the benefits of white lupin for rabbit nutrition. These findings support the role of white lupin as a viable and eco-friendly alternative to traditional protein sources, such as soybean meal, which could support productivity and sustainability in rabbit farming.

Lactational performance of dairy buffaloes affected by replacing soybean meal with an alternative microbial protein source

Thirty dairy buffaloes were used for 90 days to evaluate the impact of a novel protein source (HI-PRO®), a feed alternative rich in protein (made from Saccharomyces and Bacillus), on the productivity of nursing buffaloes. The nursing water buffaloes had an average weight of 550 ± 11.2 kg. The treatments consisted of diets containing two distinct protein sources: (1) soybean meal (44 % as the control group); and (2) HI-PRO® product. Throughout the trial, measurements of nutritional digestibility and blood metabolites (total protein, albumin, urea, and creatinine) were conducted. Quantity and composition of the milk were measured to determine the content of milk proteins, lipids, and lactose. The outcome of the results showed insignificant decrease in the buffaloes receiving HI-PRO® feed versus control group. Furthermore, there was enhancement in the fiber digestibility by approximately 2.5 % in the HI-PRO® group compared to the control group. The levels of protein, albumin, globulin, urea, and creatinine fall within the normal range for animals in good health. Using HI-PRO® resulted in a marginal improvement in milk production, increasing it by approximately 4.8 % compared to soybean meal. Furthermore, the buffaloes fed HI-PRO® showed a slightly elevated 4 % fat-corrected milk output and milk composition. To summarize, nursing buffaloes can utilize HI-PRO® as an efficient protein source in their diets, replacing soybean meal.

Effect of Replacing Corn Grain and Soybean Meal with Field Peas at Different Levels on Feed Intake, Milk Production, and Metabolism in Dairy Cows under a Restrictive Grazing.

This study assessed the effects of replacing soybean meal (SBM) and corn grain with field peas in the concentrate of grazing dairy cows on milk production, intake, ruminal fermentation, and blood indicators. Twelve multiparous lactating Holstein-Friesian cows were utilized in a replicated 3 × 3 Latin square design, comprising three periods and three treatments: (1) Pea-0 (Control diet): 6 kg dry matter (DM) of fresh pasture, 7.2 kg DM of grass silage, and 7 kg DM of a concentrate containing 0% pea; (2) Pea-30: Control diet with the concentrate composed of 30% pea; (3) Pea-60: Control diet with the concentrate composed of 60% pea. The effect of treatments on productive and metabolic parameters was evaluated using linear-mixed models. Pasture and total DM intake, milk production, and composition were unaffected by treatments. Despite the concentrates being isonitrogenous and isoenergetic, crude protein (CP) intake was slightly higher in Pea-30 and significantly higher in Pea-60 due to higher pasture CP content in the pasture grazed by these groups, leading to higher milk urea content, though within recommended ranges. Blood parameters showed no significant changes, except for plasma β-hydroxybutyrate, which was lowest in the Pea-60 treatment; however, all values were within ranges not indicative of subclinical ketosis. Ruminal fermentation parameters were similar across treatments. These findings support the use of field peas as a viable alternative to replace SBM and corn grain in concentrates, enabling similar milk production and composition in grazing dairy cows.

The composition of early lactation milk in recipient dairy cows determines success in bovine embryo transfer.

To identify new criteria for selecting recipient dairy cows for embryo transfer (ET), we retrospectively examined the effects of the composition of early lactation milk on fertility risk in ET. This study investigated the association between milk fat (FAT), milk protein (PRO), and milk urea nitrogen (MUN) levels during early lactation, based on production records, and subsequent fertility risk in ET using contingency table analysis and multivariable logistic regression analysis, which included five confounding variables. The results showed that MUN levels during early lactation were negatively associated with fertility risk in ET, while FAT and PRO levels showed no clear association. A reduction in MUN levels during the peak lactation period suggests a deficiency in dry matter intake, an inadequate protein supply, and an imbalance in the ratio of proteins to fermentable carbohydrates in the rumen, which may have adversely impacted fertility risk in ET.Monitoring MUN levels is crucial for maintaining a proper protein balance. The results obtained in this study suggest that MUN levels in the early lactation phase obtained from production records can be used as a predictor of fertility in recipients to improve the fertility risk in ET. No special techniques or costs are required for using production records, making them easy to use in clinical practice. Our findings provide valuable insights for optimizing cost-effectiveness and fertility risk in ET and their clinical applications.

Pre- and postpartum metabolizable protein supply: I. Effects on feed intake, lactation performance, and metabolic markers in transition dairy cows.

The objective of this study was to investigate the effect of increasing MP supply in the prepartum, postpartum, or both diets on intake, performance, and metabolic indicators. Multiparous Holstein cows (n = 96) were assigned to 1 of 4 treatment groups at 28 d before expected calving following a randomized block design. Prepartum diets were formulated to contain either a control (C; 85 g of MP/kg DM) or high (H; 113 g of MP/kg DM) level of estimated MP. From calving to 21 DIM, diets were formulated to contain either a control (C; 104 g of MP/kg DM) or high (H; 131 g of MP/kg DM) level of estimated MP. To control the potential confounding effect of Met and Lys supply, diets were formulated to supply an equal amount at 1.24 and 3.84 g/Mcal of ME in both prepartum diets and 1.15 and 3.16 g/Mcal of ME in both postpartum diets, respectively. The combination of a pre- and postpartum diet resulted in 4 treatment groups: 1) CC (n = 23), 2) CH (n = 24), 3) HC (n = 22), and 4) HH (n = 23). A common lactation diet (113 g of MP/kg DM) was fed from 22 DIM to the end of the observation period at 42 DIM. Milk yield and DMI were collected daily, and plasma metabolic indicators (BHB, fatty acids [NEFA], urea nitrogen [PUN], and glucose) were determined twice weekly from -28 to 28 d relative to calving and once weekly from 29 to 42 DIM. Samples with BHB ≥1.2 mmol/L between 3 and 10 DIM were considered hyperketonemia events. Milk composition was determined weekly. Milk yield during 1 to 21 DIM was greater in HH (44.7 ± 1.0 kg/d) compared with CC (39.2 ± 1.0 kg/d) and HC (38.0 ± 1.0 kg/d) and milk yield in CH (42.4 ± 0.9 kg/d) was greater than HC, respectively. From 22 to 42 DIM, milk yield was greater in CH (53.3 ± 1.0 kg/d) and HH (54.1 ± 1.0 kg/d) compared with CC (49.6 ± 1.0 kg/d) and HC (49.3 ± 1.0 kg/d). Dry matter intake (% of BW) and concentrations of milk protein, fat, and total solids were not affected by treatment. Prepartum concentrations of PUN were greater in H compared with C. From 1 to 21 DIM, PUN concentrations were greater in CH and HH compared with CC and HC. From 1 to 21 DIM, glucose concentrations were lower in HH compared with HC and BHB were greater in CH and HH compared with HC. Concentrations of NEFA, as well as the number of hyperketonemia events did not differ by treatment during this time. From 22 to 42 DIM, concentrations of NEFA were greater in HH compared with HC and concentrations of BHB were greater in CH and HH compared with HC. Overall, feeding CH or HH increased lactation performance without altering intake or hyperketonemia events. Results from this study support formulating a fresh diet to reduce the negative MP balance during early lactation.

Effect of sward species diversity combined with a reduction in nitrogen fertilizer on the performances of spring calving grazing dairy cows

The objective of this study was to evaluate the impact of sward diversification combined with a reduction of chemical nitrogen (N) fertilizer on the performance of spring calving grazing dairy cows within a farm systems experiment. Three farmlets were created; a monoculture of perennial ryegrass (Lolium perenne L.; PRG) fertilized with 250 kg N/ha (PRG-250N), a PRG - white clover (Trifolium repens; WC) sward fertilized with 125 kg N/ha (PRGWC-125N) and a multispecies sward (MSS) comprising of grasses, legumes and herbs also fertilized with 125 kg N/ha (MSS-125N). Each farmlet had its own herd of dairy cows on a total area of 18.7 ha divided into 20 paddocks. Each herd was comprised of pure Holstein-Friesian (HF) and HF Jersey crossbred (JFX) animals and randomly assigned through the 3 treatments. For 3 years (2021 to 2023), the performances of both swards (grass yield, botanical composition, nutritive value) and grazing animals (milk production and composition, body weight (BW) and body condition score (BCS)) were recorded. There were no significant differences in pasture production or sward nutritive value between sward systems and grazing season length was also similar (264 d). On average over the 3 years, PRGWC-125N contained 150 g/kg DM of legumes and the MSS-125N contained 160 g/kg DM legumes, 130 g/kg DM plantain and 40 g/kg DM chicory. Both individual cow milk and fat plus protein (Milk solids; MS) yield were lower for PRG-250N (5,018 and 452 kg, respectively), intermediate for PRGWC-125N (5,139 and 463 kg, respectively) and highest for MSS-125N (5,297 and 476 kg, respectively) while milk and MS production per hectare from grazing were similar during the study period (11,523 and 1,016 kg/ha, respectively). Breed also had a significant effect with the JFX having lower milk yield but higher fat and protein concentration compared with HF. This resulted in higher MS production per kg of BW for the JFX compared with HF (0.96 and 0.87 kg MS/kg BW, respectively). The results of this study highlight the possibility for more diverse pastures to reduce chemical N fertilizer input requirements and maintain pasture productivity while increasing animal performance within pasture-based spring calving systems.

Identification of Genetic Associations of IDH2, LDHA, and LDHB Genes with Milk Yield and Compositions in Dairy Cows.

Previous study revealed that isocitrate dehydrogenase (NADP (+)) 2, mitochondrial (IDH2), lactate dehydrogenase A (LDHA), and lactate dehydrogenase B (LDHB) genes were significantly differentially expressed in liver tissues of Holstein cows among different lactation periods and associated with lipid and protein metabolism; hence, they were considered as candidates for milk production traits. Herein, the genetic effects of the three genes on milk yield, fat, and protein traits were studied by association analysis using 926 Chinese Holstein cows from 45 sire families. As a result, five single nucleotide polymorphisms (SNPs) in IDH2, one in LDHA, and three in LDHB were identified by re-sequencing, and subsequently, they were genotyped in 926 Chinese Holstein cows by genotyping by target sequencing (GBTS). With the animal model, single-locus association analysis revealed that four SNPs in IDH2 and one SNP in LDHA were significantly associated with milk, fat, and protein yields (p ≤ 0.0491), and three SNPs in LDHB were associated with milk yield, milk fat yield, and fat percentage (p ≤ 0.0285). Further, four IDH2 SNPs were found to form a haplotype block significantly associated with milk yield, fat yield, protein yield, and protein percentage (p ≤ 0.0249). In addition, functional predictions indicated that one SNP in LDHA, g.26304153G>A, may affect transcription factor binding and two SNPs, g.88544541A>G and g.88556310T>C could alter LDHB mRNA secondary structure. In summary, this study profiled the significant genetic effects of IDH2, LDHA, and LDHB on milk yield and composition traits and provided referable genetic markers for genomic selection programs in dairy cattle.

Impact of cultural, nutrition, and lifestyle transition on human milk composition between the Orang Asli communities in Peninsular Malaysia: A study protocol.

Background: Human milk provided by healthy, well-nourished mothers represents the best food available for infants. Human milk is species-specific and recommended as the sole source of nutrition for the first 6 months of life and is an important food source until the infants reach 2 years of life. Unlike infant formula, which has a standardized composition, human milk composition varies among and within women. Aim: While many studies of human milk composition have been conducted, none have been done among the Orang Asli people in Malaysia. Hence, this study protocol is designed to determine the human milk composition of the Orang Asli in Peninsular Malaysia and how the transition of culture, nutrition, and different lifestyle experiences will affect the nutrient content of their milk. Methods: Quantitative (interviewer-administered questionnaire) and qualitative (focus group discussion) approaches will be employed in this study and in addition, laboratory works will also be carried out to analyze the nutrient composition of the milk samples collected from various Orang Asli subethnic groups in Peninsular Malaysia. Conclusion: Standardized, multipopulation studies of human milk composition are sorely needed to create a rigorous, comprehensive reference inclusive of nutrients and other factors. The establishment of any dietary parameters positively affecting the nutrient content of human milk may help design healthcare strategies in Malaysia to improve the quality of human milk and therefore the infants' health status.