Short communication: Comparative estimation of colostrum quality by Brix refractometry in bovine, caprine, and ovine colostrum

Cross-sectional study investigating the components and quality of colostrum and colostrum replacement products fed to Ontario dairy goat kids

Colostrum replacement products for use in goat kids are sourced from bovine colostrum and often used by producers to supplement or replace maternal colostrum to prevent infections. To compare the colostrum replacement products fed on-farm to caprine colostrum a cross-sectional study was undertaken. Ontario dairy goat producers were asked to collect first milking colostrum from their goats and samples of the reconstituted commercial replacement product currently in use. The frozen samples were thawed and submitted for testing of fat, protein and lactose content, IgG1 concentration and aerobic bacterial culture. Compared with caprine colostrum, the reconstituted replacement products were lower in protein (11.7%; P = 0.0007), and fat (4.6%; P < 0.0001) and higher in lactose (5.4%; P < 0.0001) on average. The average IgG1 concentration in goat colostrum (53.5 g/L; range: 16.6-1985.8) was significantly higher than in colostrum replacement products (33.7 g/L; range: 10.7-55.3) (P < 0.0001). The Brix cut-point for good quality goat colostrum (50 g/L) was calculated at 23% (sensitivity = 69.6%, specificity = 88.0%) for goat colostrum and 26% for the colostrum replacement product (sensitivity = 87.5%, specificity = 100%). The average aerobic count for goat colostrum was lower (2.95 log10 cfu/mL) than the colostrum replacement product samples that were cultured (3.85 log10 cfu/mL; P < 0.0001). Further investigation into colostrum replacement products, including on-farm storage of opened powdered product and mixing and storage of reconstituted product, is warranted. Variability in the levels of IgG1, aerobic bacterial growth and fat, protein and lactose content in colostrum replacement products also requires further exploration to determine their effects on kid health.

Effect of oxytocin use during colostrum harvest and association of cow characteristics with colostrum yield and IgG concentration in Holstein dairy cows

Our objectives were to determine the effect of oxytocin use during colostrum harvest on colostrum yield (CY) and IgG concentration in Holstein dairy cows on a commercial dairy in New York and to describe associations of cow characteristics with these outcomes. Animals were enrolled between July and October 2023 using a randomized block design, with day of enrollment as the unit of randomization. A median (range) of 10 (3 to 19) cows were enrolled/d. Treatments were 1) 40 IU Oxytocin (OXY40), 2) 20 IU Oxytocin (OXY20), and 3) an untreated control group (CNTR). Oxytocin was administered intramuscularly (IM) approximately 45 s before unit attachment in a rotary parlor. Colostrum weight was measured using the colostrum bucket-embedded scale or a platform scale when the yield was less than the smallest bucket scale. The concentration of IgG ([IgG]) in colostrum was determined using radial immunodiffusion (RID) and used to calculate total IgG, and dry matter (%) was determined by oven drying. Individual cow characteristics such as parity, calf sex, weight, dystocia score, stillbirth, milk production in wk 4 of lactation, and for multiparous cows, dry period length, previous lactation dry off linear score (LS) were collected. Data were analyzed separately for primiparous and multiparous cows using backward stepwise elimination to produce final mixed effects ANOVA models Primiparous cows (n = 201) were randomized to 35.8% (n = 72) OXY40, 32.8% (n = 66) OXY20, and 31.3% (n = 63) CNTR. Multiparous groups (n = 435) were randomized to 34.7% (n = 151) OXY40, 29.7% (n = 129) OXY20, and 35.6% (n = 155) CNTR. The median (range) CY was 6.0 (0 to 20.6) kg and [IgG] was 98.5 (0.1 to 293.6) g/L in the study population. In primiparous cows, OXY40 had a higher colostrum yield (LSM [95% CI]) of 5.4 (4.9 to 5.9) kg compared with both OXY20 (4.1 [3.5 to 4.7] kg) and CNTR (3.8 [3.3 to 4.3] kg) (P < 0.001). In multiparous cows, OXY40, OXY20, and CTNR did not differ in CY (5.9 [5.3 to 6.5], 5.7 [6.3 to 5.1], and 5.4 [6.0 to 4.8] kg, respectively, P = 0.43), but colostrum yield was greater in parity 2 compared with all other parities, cows giving birth to male calves, cows with the highest milk production at wk 4 of lactation, and with a dry period of >65 d. Oxytocin use did not affect [IgG] in either primiparous or multiparous cows (P > 0.56), but [IgG] was highest in cows in parity ≥4 and lowest in cows dry >65 d. In summary, oxytocin use at 40 IU IM in primiparous was associated with a higher CY but not [IgG]. Oxytocin use likely addressed disturbed milk ejection and therefore increased CY in heifers milked for the first time in a rotary parlor. This study confirms cow characteristics associated with colostrum production within a single herd.

A Comprehensive Review of Bovine Colostrum Components and Selected Aspects Regarding Their Impact on Neonatal Calf Physiology

Colostrum contains macro- and micronutrients necessary to meet the nutritional and energy requirements of the neonatal calf, bioactive components that intervene in several physiological aspects, and cells and microorganisms that modulate the calf's immune system and gut microbiome. Colostrum is sometimes mistaken as transition milk, which, although more nutritive than whole milk, has a distinct biochemical composition. Furthermore, most research about colostrum quality and colostrum management focuses on the transfer of maternal IgG to the newborn calf. The remaining components of colostrum and transition milk have not received the same attention, despite their importance to the newborn animal. In this narrative review, a large body of literature on the components of bovine colostrum was reviewed. The variability of these components was summarized, emphasizing specific components that warrant deeper exploration. In addition, the effects of each component present in colostrum and transition milk on several key physiological aspects of the newborn calf are discussed.

Evaluation of laboratory and on-farm tests to estimate colostrum quality for dairy cows

The objectives of this study were to evaluate different analytical methods to determine colostrum quality in dairy cattle, including one laboratory-based method (ELISA) and 4 on-farm tests. We hypothesized that the colostral IgG concentration using different analytical methods, such as ELISA (mg/mL), digital Brix refractometer (% Brix), colostrometer (specific gravity and mg/mL), an outflow funnel (seconds), and a lateral flow assay (mg/mL), were highly correlated with the reference method, radial immunodiffusion (RID; mg/mL) and would generate comparable results. Colostrum samples were collected from 209 Holstein Friesian cows on 2 commercial dairy farms in Germany. Colostrum weight and colostrum temperature were measured. Test characteristics, such as optimum thresholds, sensitivity, specificity, and area under the curve (AUC) were determined using a receiver operating characteristic curve analyses for each test. Out of 209 colostrum samples assessed by RID, 186 (89%) samples had high quality (≥50 mg IgG/mL), while 23 colostrum samples (11%) showed poor quality with IgG concentrations less than 50 mg/mL. The mean IgG concentration (±SD) was 101.3 ± 45.9 mg/mL and the range was 6.0 to 244.3 mg/mL. The Pearson correlation coefficient (r) between RID and ELISA was r = 0.78. In comparison to RID, Pearson correlation coefficients for the on-farm tests were: r = 0.79 (digital Brix refractometry), r = 0.58 (colostrometer: specific gravity), r = 0.61 (colostrometer: temperature corrected), r = 0.26 (outflow funnel) and r = 0.43 (lateral flow assay), respectively. The optimal threshold to identify high-quality colostrum using ELISA was 50.8 mg/mL with sensitivity 91.3%, specificity 92.3%, and AUC of 0.94. For the on-farm tests sensitivity ranged from 95.7% (Brix refractometry) to 60.9% (lateral flow assay). Specificity ranged from 88.6% (lateral flow assay) to 75.9% (colostrometer: temperature corrected). The AUC ranged from 0.93 (Brix refractometry) to 0.73 (outflow funnel). Based on the AUC, ELISA (0.94) and Brix refractometry (0.93) can be considered highly accurate. In conclusion, the ELISA is accurate to assess colostrum quality. Regarding the on-farm tests only the digital Brix refractometer and the colostrometer were adequate to determine colostrum quality.

Changes in colostrum ingredients of Hu sheep, as well as the missense mutation genes associated with colostrum yield

This study focused on the changes in the composition and immune evolution in milk from birth to 144 h postpartum and the genes associated with the colostrum yield of Hu sheep. Twelve Hu sheep, which were bred carefully under animal health standards and have a litter size of two kids and similar gestation length (149 ± 1 days), were used. Lambs were transferred into their own cots to avoid interference. The compositional content (i.e., fat, protein, and lactose) and some other properties, including daily colostrum yield, DM, and SNF, were determined. In addition, immunity molecules (IgG, IgA, and IgM concentrations) received remarkable attention. The DM, SNF, fat, and protein contents were higher in the first days postpartum and then dropped quickly from the time of birth to 144 h postpartum. However, the lactose content displayed an increasing pattern and reached normal milk percentage at 48 h. The highest IgG (103.17 mg/mL), IgA (352.82 μg/mL), and IgM (2.79 mg/mL) colostrum concentrations were observed at partum, decreased quickly, and finally stabilized. The change law of concentration of IgA and IgM in colostrum are the same with IgG. Furthermore, the whole-genome resequencing was performed, and a missense variant locus in the SRC gene and two missense locus variants in the HIF1A gene were significantly associated with the colostrum yield of sheep by using the whole-genome selection signal detection analysis. In conclusions, colostrum contains abundant nutrients especially immunoglobulin, and the HIF1A gene may be used as candidate genes for colostrum yield, which has important information as a basic knowledge for the Hu sheep breeding program.

Use of a Visual Scoring System to Assess External Udder Conformation and Its Relationship to Colostrum Quality and Lamb Growth Rates

In sheep raised for meat production, the relationship between external udder conformation, colostrum quality, and lamb growth rates has not received much attention. We hypothesized that ewes with a more desirable udder conformation at lambing would have greater colostrum quality and greater growth rates in lambs. Fifty Suffolk ewes were used in this study. Within 6-8 h of parturition, colostrum samples from both halves of the udder were collected and visual scoring of the udder was conducted. Colostrum quality was measured for total proteins using both optical and Brix refractometers. On day 2, day 45, and day 60 after parturition, lamb weights were recorded, and udder conformation measurements were repeated. A visual scoring system evaluating udder floor (scale 1-4), udder depth (scale 1-9), teat placement (scale 1-9), teat/mammary lesions (present or absent), and the presence of wool (present or absent) was used to assess the external udder conformation. Normal udder parameters included udder depth scores of 5 or 6; udder floor scores of 1 or 2; teat placement scores of 4, 5, or 6; and the absence of teat/mammary lesions and wool. All ewes not meeting normal parameters were considered to have an abnormal udder. The data were analyzed using the GLM procedure. Mean total colostrum protein was greater (p = 0.03) in ewes displaying a 'normal' udder conformation compared with those with an 'abnormal' conformation (14.82 ± 0.5 and 13.31 ± 0.3 mg/dL, respectively). Mean Brix values were also greater (p = 0.03) for ewes with a 'normal' udder compared to an abnormal udder confirmation (21.70 ± 0.8 and 19.54 ± 0.5, respectively). On day 2 after parturition, the mean lamb body weight was not different between ewes with 'normal' and abnormal udders (5.38 ± 0.26 vs. 5.46 ± 0.15). No differences (p > 0.05) in lamb weights were detected between ewes with normal and abnormal udder conformations on day 45 and 60 after parturition. These data provide evidence of greater colostrum total protein values and greater Brix values present in ewes with a 'normal' udder conformation. There were no differences in the weights of lambs born to ewes with normal or abnormal udder conformations.

Defining optimal thresholds for digital Brix refractometry to determine IgG concentration in ewe colostrum and lamb serum in Scottish lowland sheep flocks

This research aimed to define thresholds for ewe colostrum and lamb serum Brix refractometer measurements in lowland Scottish sheep. This would facilitate the use of this convenient, sheep-side test, enabling quick and accurate identification of poor quality colostrum and prevention of failure of transfer of passive immunity (FTPI) in lambs. Secondary aims were to identify risk factors for poor colostrum quality and FTPI in lambs. Serum samples (n = 233) were collected from lambs between 24 and 48hrs after birth, from four lowland Scottish meat sheep farms. Pre-suckle colostrum samples (n = 112) were also collected from ewes on two of these farms. Farmers provided information on litter size, ewe body condition score, ewe breed and dystocia. Duplicate digital Brix refractometer measurements were compared with immunoglobulin G (IgG) radial immunodiffusion (RID) testing for all colostrum and serum samples. Receiver operating characteristic (ROC) curves were used to redefine thresholds for Brix testing in colostrum and serum. Linear regression models were constructed with colostrum and serum IgG concentration as the outcomes of interest. Colostrum and serum IgG concentrations were highly variable. The prevalence of inadequate colostrum quality (using <50 g/L IgG on RID) was 4.5% (95% CI = 1.5 - 10.1) and the prevalence of FTPI (using <15 g/L IgG in serum on RID) was 7.73% (95% CI = 4.64-11.93). A ewe's colostrum IgG concentration was significantly and positively associated with the serum IgG concentration of her lamb(s) (p = 0.02). ROC analysis defined a Brix threshold for adequate colostrum quality of > 22.10% (sensitivity 80% (95%CI=28.4-99.5), specificity 90% (95%CI=82.3-94.8)). ROC analysis defined a Brix threshold for serum of > 8.65% for adequate passive transfer of immunity in Scottish lambs (sensitivity 94% (95%CI=72.7-99.8), specificity 82% (95%CI=76.6-87.2)). To optimise passive transfer of immunity in lambs, we suggest that ewe colostrum Brix measurements be defined as 'poor' (<22%); 'fair' (22-26%) and 'good' (>26%); and lamb serum as 'poor' (<8%); 'fair' (8-9%) and 'good' (>9%). It is recommended that these tests are used as for flock screening, using samples from multiple animals.

Review: Feeding strategies for rearing replacement dairy goats - from birth to kidding

Goat kid rearing is a key profit driver and the cornerstone of future herd productivity in dairy systems. As goat kids get older, and progress from liquid (i.e., colostrum, milk) to solid feed (i.e., concentrate, hay, pasture), there is a reduction not only in feed cost but also in labour cost, disease susceptibility and mortality rates. Hence, research on rearing dairy goats has traditionally focused on improving early neonatal performance. However, recent research reveals that early-life nutrition may have long-term effects, and consequently, impact the lifetime productive performance and health of dairy goats. Therefore, this literature review has collected research on the various aspects of rearing replacement dairy goat kids in different production systems. It summarises research on areas such as colostrum management (i.e., colostrum quality, time, volume and frequency of colostrum feeding), liquid feeding in preweaned kids (i.e., maternal suckling vs artificial, restricted vs unrestricted), weaning strategies (i.e., abrupt vs step-down), and postweaning to postpubertal nutrition in replacement dairy goats, whilst highlighting gaps in the existing literature, and areas where it would be beneficial to refine and validate current recommendations. Such information can be used in the development of management plans to maximise the benefits of early-life nutrition on the long-term productivity of dairy goats.

Colostrum Quality Assessment in Dairy Goats: Use of an On-Farm Optical Refractometer

Failure of passive immunity transfer is one of the main causes of increased susceptibility to infectious agents in newborn kids. To ensure successful transfer of passive immunity, kids need to be fed high-quality colostrum, containing an adequate concentration of IgG. This work evaluated the quality of colostrum obtained in the first 3 days postpartum from Malagueña dairy goats. The IgG concentration in colostrum was measured using an ELISA as a reference method, and it was estimated by optical refractometer. Colostrum composition in terms of fat and protein was also determined. The mean concentration of IgG was 36.6 ± 2.3 mg/mL, 22.4 ± 1.5 mg/mL and 8.4 ± 1.0 mg/mL on days 1, 2 and 3 after parturition, respectively. Brix values obtained using the optical refractometer were 23.2%, 18.6% and 14.1% for days 1, 2 and 3, respectively. In this population, 89% of goats produced high-quality colostrum with IgG concentrations of >20 mg/mL on the day of parturition, but this percentage declined dramatically over the following 2 days. The quality of the fresh colostrum estimated with the optical refractometer was positively correlated with those obtained using ELISA (r = 0.607, p = 0.001). This study highlights the importance of feeding first-day colostrum to newborn kids and demonstrates that the optical Brix refractometer is suitable for the on-farm estimation of IgG content in colostrum.

Metabolic profile of transition period in ewes and its influence on passive immunity transference in lambs

The intensification of ewe production, focusing on increasing prolificity, results in a higher incidence of metabolic disorders, especially in the transition period, which can lead to production losses with consequences for the health of the animals. The objective of this study was to evaluate the metabolic profile in transition period Lacaune ewes according to the parity and litter size born and its influence on the transference of passive immunity. Nineteen Lacaune ewes, with initial mean body weight of 76.36 ± 10.37 kg (SD), kept in a semi-extensive system and receiving the same diet, were used. Ewes were classified according to parity (primiparous and multiparous) and the litter size born at parturition (1, 2, and 3). On days - 14, - 7, and - 4 of the expected date of parturition and on days 1, 4, 7, and 14 days postpartum, blood sampling, the evaluation of the body condition score (BCS), and the weighing of animals were performed. Blood samples were taken from the lambs 48 h after birth. Colostrum was collected up to 6 h postpartum to determine the brix percentage. Serum concentrations of total plasma proteins (TPP), albumin, aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), paraoxonase (PON1), calcium (Ca), and magnesium (Mg) were evaluated. In lambs, the blood parameters evaluated were TPP, albumin, GGT, and PON1. Lamb plasma was used to estimate colostrum efficiency, brix percentage immunity, and total plasma protein (PPT). Productive data, pre- and postpartum metabolic variables for ewes, lambs, and those related to colostrum brix were analyzed. The BCS had a reduction (p < 0.0001) in the postpartum period, which is evidenced on days 7 and 14 (2.88 and 2.73, respectively). Serum concentration of BHB presented the highest concentrations in the prepartum period for ewes that gave birth to triplets, from day - 14, and for ewes that gave birth to twins on day - 4 (p = 0.0245). Serum concentration of NEFA demonstrated the highest value on day 14 in primiparous (1.07; p = 0.0402). Calcium had the lowest concentrations on day 1 (8.85 mg/dl, p < 0.0001) and magnesium on day 3 (1.79 mg/dl, p < 0.0001) postpartum. The multiparous with two lambs had higher brix percentages (30.5%), and the lowest value was observed in primiparous ewes that gave birth to a single lamb (27.06%; p = 0.0395). Triplet lambs had the lowest weight (3.73 kg, p = 0.0007), and the best brix percentage in plasma was observed in twins (10.29%, p = 0.0174). Regardless of the parity, the ewes that presented the greatest metabolic challenge were those that gave birth to triplets, and these lambs presented the worst immunity and the lowest live weight. The quality of colostrum was influenced by the parity, and multiparous ewes that gave birth to triplets had the lowest brix percentage in the colostrum.

Validation of a handheld refractometer to assess Merino ewe colostrum and transition milk quality

Colostrum quality is generally defined by the IgG concentration in colostrum, and many methods have been used to assess it. Methods to measure colostrum quality both in the laboratory and in the field have been validated in cattle; however, this is only a recent topic of interest for sheep colostrum. Laboratory-based methods are often time consuming and require trained personnel compared with new handheld evaluation tools such as the digital Brix refractometer, which gives real-time results. The aims of this study were to (1) evaluate the relationship between the digital Brix refractometer and constituents indicative of quality (IgG, protein, fat, and lactose) in colostrum and transition milk, and (2) determine an appropriate Brix % cut-off value for the Brix refractometer in sheep colostrum and transition milk. The study used 50 colostrum samples (collected at 0 h postpartum, before lambs' sucking) and 169 transitional milk samples (collected at 4 and 24 h postpartum, after lambs had sucked) collected over 6 lambing trials in 2 years (2019 and 2020). We concluded that the Brix refractometer results correlated weakly with IgG concentration determined by radial immunodiffusion assay in colostrum collected at 0 h postpartum (r = 0.11) and in transition milk collected at 4 h postpartum (r = 0.12); however, a moderate to strong correlation was shown in transition milk samples collected at 24 h (r = 0.66). Brix % was significantly correlated with fat %, lactose %, and protein % at all timepoints. To determine an appropriate Brix % cut-off value indicating an IgG concentration of 20 mg/mL, we analyzed sensitivity and specificity of the Brix refractometer at 0, 4, and 24 h. In samples collected at 0 and 4 h, the highest combination of sensitivity, specificity, and accuracy was achieved at a Brix % cut-off value of 29%; in samples collected at 24 h postpartum, a Brix % cut-off value of 27% gave the highest sensitivity, specificity, and accuracy. Overall, the Brix refractometer has potential as a useful in-field tool for researchers and producers in both extensively and intensively managed flocks to measure and determine the quality of sheep colostrum and transition milk.

Essential and Toxic Mineral Content and Fatty Acid Profile of Colostrum in Dairy Sheep

Simple Summary

Colostrum is of interest to the scientific community because of its nutritional and therapeutic capabilities. The aims of this study were to characterize the macro and micro composition of colostrum from Sarda dairy sheep and to compare it with the composition of the mature milk of the same breed. The results of this survey showed a large variation in the immunoglobulin concentration in colostrum, which could affect the acquisition of passive immunity by lambs. The strong correlation between immunoglobulin G and the total protein content suggests that this can be used to estimate the immunoglobulin content in sheep colostrum. The concentration of essential minerals is higher in colostrum than in milk as a result of mineral salt block supplementation at the end of gestation. Colostrum has a significantly different fatty acid profile than milk, and this is due to the specific needs of newborn lambs.

Abstract

Colostrum is a major source of immunity in ruminants. It allows the transfer of antibodies from the mother to the fetus, and it is the exclusive source of nutrients for the newborn. The objectives of this study were (i) to characterize the macro and the micro composition of colostrum; (ii) to analyze the antioxidant capacity, fatty acid profile, and essential and toxic mineral content of colostrum; and (iii) to compare FA profiles and the amount of trace elements between colostrum and mature milk. For these purposes, samples of colostrum and milk were collected from a representative sample of animals from eight sheep dairy farms in the north of Sardinia (Italy). Fat, proteins, and seven essential and toxic minerals were measured in all samples of colostrum and milk. Furthermore, the FA profile was also measured in both matrices, while total antioxidant capacity was measured only in colostrum samples. The average amounts of fat and protein (TP) concentration in colostrum were 7.8% and 16%, respectively. Additionally, an average amount of 40 ± 20 g dm⁻³ was found for immunoglobulin G (IgG). As regards the antioxidant capacity of colostrum, a large variation was observed between samples from different farms for test 2, 2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), which was 30 ± 10% (mean ± standard deviation). High levels of selenium (Se), zinc (Zn), and copper (Cu) were found in colostrum (200 µg kg⁻¹, 25,000 µg kg⁻¹, and 1200 µg kg⁻¹, respectively). A strong positive correlation between TP and IgG was observed (r = 91%). In colostrum, the amount of IgG is positively correlated with Se and Zn, as they are essential minerals to the immune system. The FA profile demonstrated higher levels of medium and long chain fatty acids in colostrum than in mature milk, and this is mainly true for arachidonic acid (ARA), ecosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). This study provided new information on the quality of colostrum in Sarda dairy sheep and showed the different composition of fatty acids between colostrum and mature milk.

Immunoglobulin G Concentrations in Alpaca Colostrum during the First Four Days after Parturition

Simple Summary

During the first days after parturition, mammalian milk (colostrum) is specifically formulated to nourish newborns. Immunoglobulins are a particularly important component for newborn New World camelids, as their immune system is almost totally dependent on the intestinal transfer of colostral immunoglobulins to acquire passive immunity. In this study, colostrum samples were collected from 20 alpaca mares in the first four days after parturition and analyzed for their immunoglobulin concentration. Sampling started on the day of parturition. The associations of immunoglobulins with other components were determined. The immunoglobulin G (IgG) concentrations decreased significantly within the first four days after parturition. The correlation coefficients between IgG content and the content of various minerals were significant but variable. The correlation between IgG content and fat and lactose content was negative but between IgG content and protein content was highly positive. This strong association could be used for a brief estimation of the IgG content of the colostrum based on the measured protein concentration. The results of the present study can be used for the development of colostrum replacers where motherless rearing is required.

Abstract

Colostrum provides the newborn with nutrients and immunoglobulins. Immunoglobulins and their intestinal transfer play a major role in the immune system of neonates since they are born agammaglobulinemic. In this study immunoglobulin G (IgG) content was determined in alpaca colostrum and the correlations of the IgG concentration by fat, protein, lactose and minerals were calculated. Colostrum samples were collected daily from 20 multiparous alpaca mares during the first four days after parturition. The IgG concentrations were determined by radial immunodiffusion using a Camelid IgG Test Kit. The IgG concentration decreased significantly from 26,319 mg/dL on day 1 to 3848.8 mg/dL on day 4. There were significant correlations between IgG concentration and the other components of the colostrum. While the correlations between IgG and fat (r = −0.69, p ≤ 0.001) and lactose (r = −0.64, p ≤ 0.001) were negative, the correlations with protein (r = 0.91, p ≤ 0.001), magnesium (r = 0.86, p ≤ 0.001) and cobalt (r = 0.87, p ≤ 0.001) were strongly positive. Due to the strong association, the colostrum protein concentration could be used for a brief estimation of the IgG content.

Validation of Brix refractometer to estimate immunoglobulin G concentration in goat colostrum

Background and Aim:

Immunoglobulin G (IgG) concentration is high in goat colostrum, particularly in the first few hours after parturition, and this is important for the kid’s immunity and growth. IgG levels vary depending on several factors, including breed, disease status, colostrum management, handling, and collection time postpartum. A handheld optical refractometer, an affordable instrument that is simple to use in the field, is used widely in dairy farms to measure total solids. However, it can also be applied to estimate colostrum IgG content on the basis of comparison with standard measurement methods, usually radial immunodiffusion. Studies comparing %Brix values in relation to IgG concentration measured using enzyme-linked immunosorbent assay (ELISA) in goats are limited. The present study aimed to evaluate the use of a handheld optical Brix refractometer for the measurement of IgG concentration in goat colostrum, compare results with those using ELISA, and estimate the %Brix cutoff value equating to low-quality colostrum.

Materials and Methods:

Colostrum samples were collected on day 0 from 21 goats (nine Black Bengal, six Saanen, and six of their crossbred offspring) and were frozen. Subsequently, they were analyzed for IgG concentration using a goat-specific ELISA test and Brix percentage using a handheld refractometer. The optimum %Brix cutoff value for the evaluation of colostrum quality was evaluated.

Results:

The mean IgG concentration and %Brix in colostrum were 10.60±0.64 mg/mL and 25.0±0.9, respectively. There was a significant (p<0.01) correlation between %Brix and IgG concentration. For an IgG concentration of 6.9 mg/dL, the cutoff value for %Brix was 18.5, equating to high specificity (100%) but low sensitivity (50%). A higher %Brix cutoff value of 21.5 showed high specificity (95%) and high sensitivity (100%).

Conclusion:

A Brix refractometer can be used to estimate goat colostrum quality with a proposed %Brix cutoff value of <18.5%-21.5% for poor-quality colostrum.

Evaluation of Brix Refractometry to Estimate Immunoglobulin G Content in Buffalo Colostrum and Neonatal Calf Serum

Simple Summary

The protective effects of colostrum in relation to the incidence and severity of newborn ruminant diseases are well established. Neonatal calf depends on the timely supply of high-quality colostrum to prevent the failure of passive transfer of immunoglobulins (Ig), which has been linked to increased risk of different diseases and mortality in early stages of life. Despite the relevance of Buffaloes (Bubalus Bubalis) in world dairy production, the available knowledge regarding colostrum quality management remains scarce for this species. Therefore, the objective of this study was to evaluate the utility of a simple and rapid tool such as a digital Brix refractometer to estimate colostrum quality and for predicting the success of passive transfer of immunoglobulin G (IgG) in Buffalo calves. For this aim, correlation analysis was performed between Brix results and ELISA-IgG determination from colostrum and serum samples. A strong correlation was found between Brix measurements and IgG content in colostrum and serum samples. Moreover, cut point values for Brix measurements for colostrum and serum samples were determined. Brix refractometry was found to be an acceptable tool for on-farm estimations of colostrum quality and passive immunity transfer (PIT) in Buffalo calves.

Abstract

Brix refractometry has been widely demonstrated to be a useful tool for monitoring colostrum management program and passive immunity transfer (PIT) in Bovines, but its suitability has never been verified in Buffalo. Therefore, the objective of this study was to evaluate the utility of a simple and rapid tool such as a digital Brix refractometer to estimate colostrum quality and for evaluating the success of passive transfer of immunoglobulin G (IgG) in Buffalo calves. The optimal cut points levels for Brix Refractometry for distinguishing good- and poor-quality colostrum and for assessing the adequacy of passive immunity transfer in calves were determined. For this aim, 26 first-milking maternal colostrum (MC) were collected from first-calf heifers. Blood samples were obtained from their calves at birth (T0) and 72 hours after (T3). Colostrum and Serum IgG content were determined by indirect enzyme-linked immunosorbent assay (ELISA), whereas total protein (TP, g/dL) and percentage Brix (%Brix) by means of a digital Brix refractometer. The mean colostrum IgG was 64.9 ± 29.3 mg/mL. The mean serum %Brix at T3 was 9.6 ± 0.9 %. The mean serum IgG content at T3 was 11.1 ± 2.0 mg/mL. Pearson’s correlation coefficient (r_p) was determined between Brix and ELISA measurements: colostrum %Brix showed a significant correlation with serum %Brix (r_p = 0.82, p < 0.001); serum %Brix was highly correlated with serum TP (STP, g/dL) (r_p = 0.98, p < 0.001) and serum IgG (mg/mL) (r_p = 0.85, p < 0.001). A cut point of 18% Brix to estimate samples of MC ≥ 50 mg/mL from first-calf heifers was more appropriate for the buffalo. A cut point of 8.4% Brix resulted in the greatest percentage of calf serum samples being correctly classified. Based on our findings, a digital Brix refractometer could be a useful tool to monitor colostrum quality and to estimate PIT in Buffalo calves.

Suitability of Protein Content Measured by MilkoScan FT-Plus Milk Analyzer to Evaluate Bovine and Ovine Colostrum Quality

Simple Summary

A rapid and reliable method for assessing colostrum quality is needed to ensure enough immunoglobulins available to offspring in order to avoid the failure of the passive transfer of immunity. This study evaluates MilkoScan FT-plus as a rapid tool for the evaluation of immunoglobulin content indirectly by protein content measurement and thus colostrum quality with a particular focus on bovine and ovine colostrum. The results indicate that MilkoScan FT-plus has good agreement with the reference method for the measurement of immunoglobulin concentration in colostrum represented by the radial immunodiffusion method.

Abstract

The objective of this study was to evaluate MilkoScan FT-plus for the estimation of the immunoglobulin G (IgG) content in bovine and ovine colostrum. Between April and May 2016, a total of 94 colostrum samples (54 from Simmental dairy cows and 39 from Sarda ewes) were collected within 6 h (T0) and after 24 h (T24) from parturition. Colostrum samples were subjected to the radial immunodiffusion (RID) assay for the quantification of IgG and to MilkoScan FT-plus for the estimation of protein content (TP, %), which was then used as an indirect method for the evaluation of colostrum quality. To compare the two methods, correlation and regression analysis of IgG quantification by RID and protein (%) content estimation by MilkoScan FT-plus data was performed using Procedure CORR and Procedure REG of SAS, respectively (version 9.3, SAS Institute Inc., Cary, NC, USA). Thresholds for the classification of good colostrum quality (as determined by RID assay, the gold standard method) were set at 50 g of IgG/L in cows and 20 g of IgG/L in ewes. The concentration of IgG in bovine colostrum assayed by RID showed a variation ranging from 41.45 to 199.97 g/L with an average of 99.85 ± 40.84 g/L at T0, and from 2.83 to 75.93 g/L with an average of 19.76 ± 19.01 g/L at T24. Regarding ovine colostrum, the concentration of IgG assayed by RID ranged from 34.45 to 156.32 g/L with an average value of 77.82 ± 37.58 g/L at T0, and from 5.6 to 69.74 g/L with an average of 27.90 ± 19.81 g/L at T24. Colostrum TP ranged from 3.70 to 23.96% for bovine colostrum and 6.32 to 22.88% for ovine colostrum using MilkoScan FT-plus. MilkoScan FT-plus and RID data were highly and significantly correlated (r = 0.91 for bovine and r = 0.94 for ovine colostrum), and regression analysis showed a strong relationship between IgG concentration provided by RID assay and TP provided by MilkoScan FT-plus (R² = 0.84 and 0.88 for bovine and ovine, respectively). Optimal cut-off points for the greatest accuracy of TP (%) determined by MilkoScan FT-plus were 12.8% in cows [with 88.9% sensitivity (Se) and 100% specificity (Sp)] and 9% in ewes (with 96.7% Se and 100% Sp). In conclusion, these outcomes indicate that MilkoScan FT-plus as an indirect method may be a reliable tool for the estimation of the total IgG concentration and quality in bovine and ovine colostrum. Moreover, the cut-off levels of 12.8% for bovine and 9% for ovine of TP, seem sufficient to ensure that all poor-quality colostrum can be classified as such, with only a low proportion of good-quality colostrum being misclassified as poor-colostrum, thereby increasing the probability of delivering good-quality colostrum to new-born calves and lambs.