The primary objective of the current work was to determine whether pH could be used as a proxy measure for bacterial contamination (using reference standard sheep blood agar plates to measure total bacteria counts [TBCs] and MacConkey agar plates to measure total coliform counts [TCCs]) of bovine colostrum (BC). The hypothesis for this work was that bacteria produce acid by-products from their metabolism, thereby more highly contaminated BC is likely to be more acidic, based on lower pH measurement. A secondary objective was to identify optimal thresholds for pH to identify colostrum highly contaminated with total bacteria or coliform species, with industry thresholds for highly contaminated colostrum being TBCs > 100,000 CFU/mL and TCCs > 10,000 CFU/mL. One hundred and one samples were purposively selected from previously frozen BC samples. Sample pH was measured using a pH meter in duplicate, and bacteria counts were measured using the reference tests of 5% sheep blood agar and MacConkey agar plates for TBC and TCC, respectively. Small decreases in pH measurement were associated with increases in bacterial contamination of BC, particularly coliform species, which are those most implicated in the disruption of IgG absorption from colostrum. There was a statistically significant relationship between pH measurements and log-transformed bacterial measurements.

This research communication aimed to describe the concentrations of major bone metabolic markers in colostrum from dairy cows on the day of calving and to clarify their associations with parity and the incidence of milk fever (MF). Forty-five Holstein cows were categorized into three groups based on parity: P1 (first calving; n = 18), P2 (second calving; n = 11) and P3 (third to sixth calving; n = 16). Within the P3 group, 6 cows developed MF within a few hours after calving (MF cows), whereas 10 showed no signs of MF (non-MF cows). Concentrations of osteoprotegerin (OPG), tartrate-resistant acid phosphatase isoform 5b (TRAP5b), cross-linked N-telopeptide of type I collagen (NTx), bone-specific alkaline phosphatase (BAP or ALP3) and calcium (Ca) were measured. With increasing parity, serum concentrations of Ca, ALP3 and TRAP5b significantly declined (P < 0.001–0.05). Parity also significantly influenced colostral bone markers: colostral BAP was highest in the P2 group (P < 0.01). Among P3 cows, serum Ca concentrations were significantly lower in MF cows than in non-MF cows, although no significant differences were observed in colostral Ca concentrations. Although no statistically significant differences were detected in other colostral bone metabolic markers between MF and non-MF cows, colostral OPG concentrations tended to be higher in MF cows (P = 0.088). Across all 45 cows and within the P3 group, colostral OPG was moderately and positively associated with serum OPG, as well as with both colostral and serum NTx concentrations. In conclusion, colostral OPG concentration in parturient cows with three or more parities may serve as a useful indicator for reflecting the bone metabolic status of dairy cows with and without MF.

Minerals are supplemented routinely to dairy cows during the dry period to prevent metabolic issues postpartum. However, limited information exists on the impacts of mineral supplementation on colostrum carotenoids. This study aimed to determine the effects of prepartum supplementation with three micro-nutrients; inorganic selenium (INORG), organic selenium (ORG) or rumen-protected choline (RPC) on the carotenoid content of bovine colostrum and transition milk (TM) from pasture-based dairy cows. A total of 57 (12 primiparous and 45 multiparous) Holstein-Friesian (HF) and HF × Jersey (JEX) cows were supplemented daily for 49 ± 12.9 d before calving. Colostrum samples were collected from all cows immediately postpartum and TM one to five (TM1–TM5) were collected from a sub-set of 15 cows (five per treatment group) at each consecutive milking postpartum. Carotenoid concentration was determined using ultra-high performance liquid chromatography – diode array detection (UHPLC-DAD). With the use of transmittance, the colour index and colour parameters a*, b* and L* were used to determine colour variations over this period. Prepartum supplementation did not have a significant effect on colostrum β-carotene concentration or colour. Positive correlations between β-carotene and colour parameter b* (R2 = 0.671; P < 0.001) and β-carotene and colour index (R2 = 0.560; P < 0.001) were observed. Concentrations of β-carotene were highest in colostrum (1.34 μg/g) and decreased significantly with each milking postpartum (TM5 0.31 μg/g). Breed had a significant effect on colostrum colour with JEX animals producing a greater b* colostrum than HF animals (P = 0.030). Primiparous animals produced colostrum with the weakest colour compared to second or ≥third parity animals (P = 0.042). Despite statistical increases in the b* parameter in colostrum from JEX cows and multiparous cows, β-carotene concentrations did not significantly increase suggesting that other factors may influence colostrum colour. The b* parameter may be used as an indicator for estimating carotenoid concentrations in colostrum and TM, particularly when assessed via transmittance spectroscopy.

In this study it is hypothesized that there are differences between immunoglobulin G (IgG) content in colostrum from beef (Chianina, Podolica) and dairy (Holstein Friesian) cows and that variables such as breed, and parity can influence IgG content. The further objective was to determine if these factors may vary in terms of sensitivity, specificity and the cut point when data obtained with the digital Brix refractometer is compared with the gold standard radial immunodiffusion assay (RID). A total of 90 samples of first-milking colostrum were collected within 2 h after parturition. IgG concentration was determined indirectly by digital Brix refractometer and directly by RID. Results obtained by RID were compared among breed and parity. For the digital Brix refractometer, sensitivity and specificity to detect colostrum with an IgG concentration lower than 50 g/l were calculated and the optimal cut-point was selected for each breed. Samples containing less than <50 g/l IgG accounted for 15.9% of the total. Parity influenced colostral IgG concentration and beef cows had a higher mean concentration of IgG (101.1 g/l in Chianina and 90.6 g/l in Podolica) than dairy cows (71.1 g/l in Holstein Friesian) First parity Chianina cows had the highest IgG mean content (116.1 g/l). At the optimal cut-point for Brix refractometer (20%) sensitivity and specificity were 0.93 (0.84–0.97) and 0.81 (0.70–0.88), however, a breed-related cut-point could be used to reduce evaluation error. Linear regression modeling showed that refractometer data were related to RID (r = 0.78). Results obtained suggest that breed and parity can influence IgG content of colostrum and, despite the Brix refractometer being an excellent on-farm tool, a breed-based definition of optimal cut point is needed.

Provision of good quality colostrum is essential for the passive immunity and nutrition of newborn calves. In order to better predict the quality of colostrum and the transfer of passive immunity, the relationships between colostrum components and between calf serum components were examined in this study. Samples of bulk tank milk, colostrum pooled from several cows 0–4 d postpartum, and colostrum collected from individual cows twice daily for 3 d post-partum were compared. With the exception of fat percentage, there were strong correlations between the levels of the components in the pooled colostrum and in the individual cow colostrum collected 0–1 d postpartum. The correlations between total solids as measured by Brix refractometry and total protein, immunoglobulin G (IgG), lactose % and protein % in colostrum within 1 d postpartum and pooled colostrum were 0.92, 0.90, −0.88 and 0.98, respectively. These high correlations enabled these colostrum components to be accurately predicted from Brix % and therefore, the volume of colostrum required to feed neonate calves can be optimised based on Brix refractometry to avoid failure of passive immunity transfer. To assess whether the components obtained from colostrum were correlated in calf blood, newborn calves were separated from their dams before suckling and blood sampled before feeding (day 0), and on days 1 and 7, after receiving colostrum or milk twice a day. The correlations between glucose, total protein, IgG, and gamma-glutamyl transferase (GGT) levels in the calf blood were lower than the correlations observed between the colostrum components. The highest correlation was between serum protein measured by refractometer and serum IgG within one week postpartum. GGT activity was not a good indicator of serum IgG levels. However, serum protein refractometer measurements predicted serum IgG level with high accuracy, providing an on-farm test to determine that calves have received sufficient passive immunity and colostrum components.

Failure of passive transfer (FPT) has health, welfare and economic implications for calves. Immunoglobulin G (IgG) concentration of 370 dairy calf serum samples from 38 Scottish dairy farms was measured via radial immunodiffusion (RID) to determine FPT prevalence. IgG concentration, total bacteria count (TBC) and total coliform count (TCC) of 252 colostrum samples were also measured. A questionnaire was completed at farm enrollment to investigate risk factors for FPT and poor colostrum quality at farm-level. Multivariable mixed effect logistic and linear regressions were carried out to determine significant risk factors for FPT and colostrum quality. Prevalence of FPT at calf level was determined to be 14.05%. Of 252 colostrum samples, 111 (44.05%) failed to meet Brix thresholds for colostrum quality. Of these 28 and 38 samples also exceeded TBC and TCC thresholds, respectively. Increased time between parturition and colostrum harvesting was numerically (non-significantly) associated with a colostrum Brix result <22%, and increased time spent in a bucket prior to feeding or storing was significantly associated with high TBC (≥100 000 cfu/ml and also ≥10 000 cfu/ml). High TBC values in colostrum were significantly associated with lower serum IgG concentrations. This study highlights associations between colostrum quality and FPT in dairy calves as well as potential risk factors for reduced colostrum quality; recommending some simple steps producers can take to maximise colostrum quality on farm.

Preservation of colostrum for neonatal dairy calves has seldom been seldom in recent years, much of the peer reviewed literature having been published in the 1970s and 1980s. First milking colostrum is high in bioactive immune enhancers such as immunoglobulins, lactoferrins, lysozymes and cytokines and is vital to confer passive immunity to newborn dairy calves to promote their health, welfare and future productivity. Bovine colostrum is advisedly restricted from the bulk milk supply for the first 8 milkings post calving due to high somatic cell counts and the risk of antimicrobial residues. As such, many producers refer to ‘colostrum’ as not only the first milking post calving, but also the aformentioned ‘transition’ milk. Colostrum is preserved in order to protect supply for feeding when production may be poor or where there is a glut of colostrum such as in seasonal calving systems. There are multiple reasons for newborn calves not to have access to their dam's colostrum, including multiple births, acute mastitis or maladapted maternal behaviour, especially in first lactation heifers. Shortages in colostrum may also be precipitated by purposeful discarding of colostrum from cows infected with Mycobacterium avium subsp paratuberculosis and Mycoplasma bovis. Broadly, colostrum may be preserved using low temperature (refrigeration or freezing) or chemical preservatives. The aim of this scoping review article was to identify options for preservation and gaps in research and to propose best practice for colostrum preservation.

This study aimed to identify and quantify the various stem-like cell types in dairy cows’ colostrum and milk at the onset of lactation. Five second parity Holstein cows were monitored from calving until the seventh-day postpartum. Mammary secretions were collected immediately after calving, then every 3 h until 12 h during day (d) 0, and during morning milking on d 1, d 2, d 4 and d 7. Cells were prepared from mammary secretions and analysed by flow cytometry using relevant cellular markers. The highest total and viable cell concentrations were observed in colostrum collected at calving and up to 6 h, with these concentrations decreasing substantially in samples collected later at d 0. Then, the concentrations of both total and viable cell populations continued to slowly decrease until d 7, the kinetic curves reaching a baseline plateau. Flow cytometry showed that the CD49fposCD24pos population, which identifies mammary epithelial stem cells, represented about 0.9% of viable cells at calving and about 0.1% 12 h later, the mammary epithelial stem cell concentration therefore being at its highest level in the very first colostrum. In contrast, the percentage of mesenchymal stem-like cells, defined as the population of CD34negCD105posCD90posCD29pos cells, was roughly constant (≈0.3%) during the first two milkings and decreased mainly during the first day to a basal level close to 0. Concerning haematopoietic stem-like cells, defined as the CD45negCD34posCD117posCD90pos cell population, they were only observed in the colostrum collected at calving. All the types of stem cells studied here were therefore only present in substantial quantities in the colostrum of the very first hours after calving, a period during which the calf’s intestine is permeable, possibly allowing the transfer and integration of these cells in the tissues of the newborn calf.

This research paper addresses the hypothesis that an oral supplementation with organically modified clinoptilolite will improve colostrum quality in primiparous dairy cows whilst having no adverse effects on the cows' health. A total of 36 pregnant Holstein primiparous dairy cattle were randomly assigned to receive daily oral drenching, two hours following morning feeding, with 1 l of water containing either 0 g/l (n = 16) or 150 g/l (n = 20) of clinoptilolite. Treatment lasted from 24 ± 4 d prior to expected parturition until two days postpartum (pp). Colostrum was collected at 2 to 3 h, 12, 24 and 36 h pp and blood samples were collected at 24 ± 4 and 4 ± 2 d prior to parturition and 1, 2 and 7 d pp. Overall mean dry matter, fat and total protein percentage as well as IgG concentration and mass were significantly greater in colostrum collected from cattle drenched with clinoptilolite (total protein increased by 15% and IgG concentration and mass by 21 and 38% respectively at first sampling and further at second sampling). Total γ globulin and most other blood serum biochemistry parameters did not differ between cattle treated and not treated with clinoptilolite, the only exception being the fast anionic γ globulin fraction that was 17% greater at 4 ± 2 d prior to parturition and 10% lower on the 1st day pp in treated cattle. These results showed that organically modified oral clinoptilolite supplementation at 150 g/d significantly increases the IgG concentration in colostrum and has no adverse effects on the energy status, protein, lipid, and mineral metabolism in primiparous dairy cattle during prepartum period.

The quality of colostrum is essential for the successful transfer of passive immunity and the early development of the immune system in newborns. This research was conducted with the aim of evaluating the agreement between measurements from different equipment: colostrometer, digital Brix refractometer and optical Brix refractometer, using fresh colostrum samples maintained at 21°C. Colostrum samples were collected from two farms (n1 = 31 and n2 = 193). Farm 1 included females from second to ninth lactation, comprising 15 Holstein Friesian (HF), 5 Jersey and 11 Holstein × Jersey crossbreeds. Farm 2 had HF heifers and cows from first to seventh lactation. Immunoglobulin content was assessed indirectly with a colostrometer and both types of Brix refractometers (digital and optical). For the correlation analysis, Pearson's product-moment method was used to assess the linear association between the equipment, followed by a Student's t-test and comparison of the obtained values with specific correlation coefficients (50%, 70%, 90% and 99%). There was a 98% correlation between the refractometers on Farm 1, which was significantly higher (P < 0.0001) than the commonly used reference values for weak (50%), moderate (70%) and strong (90%) correlations, and statistically equivalent to a 99% correlation. This indicates a very high, positive linear association between the digital and optical Brix refractometers. On Farm 2, a 97% correlation was found between the refractometers, which was significantly higher (P < 0.0001) than the specific reference values of 50%, 70% and 90%, but significantly lower than a 99% correlation.

Colostrum (CM) and transition milk (TM) are crucial for neonatal development but knowledge about the changes in their composition in dairy goats is still limited. The aim of this study was to characterise the immunological, lipid and microbial changes from CM to TM in Guanzhong dairy goats, an indigenous, highly productive Chinese breed. Milk samples were collected from eight primiparous goats at day 0 (CM) and day 7 (TM) postpartum. Immunoglobulin concentrations (IgG, IgA, IgM) were measured by ELISA, long-chain saturated fatty acids (FA) were analysed by gas chromatography, and bacterial communities were profiled by 16S rRNA gene amplicon sequencing. Microbial functions were inferred using PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) software based on KEGG (Kyoto Encyclopedia of Genes and Genomes) orthologs. Immunoglobulin concentrations declined significantly from CM to TM, reflecting a transition from immunoprotection to food supply. The TM had increased concentrations of long-chain saturated FA, particularly palmitic acid (C16:0) and stearic acid (C18:0) and higher concentrations of branched-chain FA, suggesting an adaptation to the growing energy demands of the newborn. Although overall microbial diversity was stable, taxonomic shifts were observed. CM was enriched in Emticicia, which may be involved in oligosaccharide degradation, while TM had higher abundance of Faecalibacterium, Ruminococcus and Salinicoccus, genera associated with SCFA production and intestinal development. Functional predictions indicated enrichment of cold shock and haem biosynthetic pathways in CM and enhanced carbohydrate degradation pathways in TM. Correlation analyses revealed relationships between specific FA and bacterial genera, suggesting interactions between host, microbes and nutrients that may influence milk functionality. This integrative analysis of milk components during early lactation provides new insights into the compositional and functional dynamics of goat milk.