Donkey milk study: IgG in colostrum during the first 24 hours (Turini 2020)

In nine Amiata donkey mares, the IgG content in colostrum decreased from 1.95 log10 mg/mL immediately after birth (around 89 mg/mL) to 1.40 log10 mg/mL after 24 hours (around 25 mg/mL). In the foals' blood, IgG increased from 8.97 to 14.91 mg/mL during the same period.

The study in brief

• Original title: Evaluation of jennies' colostrum: IgG concentrations and absorption in the donkey foals. A preliminary study
• Authors: Turini L., Bonelli F., Nocera I. et al.
• Journal: Heliyon, 6(8), e04598 (2020)
• Country: Italy · Study type: Animal study

How it was investigated

Ten Amiata donkey mares from a regional stud farm (Le Bandite di Scarlino, Tuscany) were cared for with their foals at the University of Pisa Veterinary Clinic during the 2019 foaling season; nine mare-foal pairs were evaluated. The mares were fed grass hay ad libitum and a commercially available concentrate feed according to NRC recommendations; the foals remained with their mothers. Colostrum was collected by hand separately from the left and right halves of the udder immediately after birth as well as 6, 12 and 24 hours later (72 samples), at the same time blood serum from the foals was collected (36 samples).

Important figures

• 9 – evaluated Amiata donkey mares with foals (10 included)
• 72 – colostrum samples (2 udder halves × 4 time points × 9 mares)
• 1.95 log10 mg/mL – IgG in colostrum immediately after birth (corresponds to around 89 mg/mL)
• 1.76 log10 mg/mL – IgG in colostrum after 6 hours (around 58 mg/mL)
• 1.40 log10 mg/mL – IgG in colostrum after 24 hours (around 25 mg/mL)
• 0.0244 – mean decrease of colostrum IgG in log10 mg/mL per hour

Results

Nine of the ten included mare-foal pairs were evaluated; one pair was excluded from the evaluation. The mares were on average 12.11 ± 4.07 years old and had foaled 4.62 ± 2.34 times; four foals were male, five female.

There was no significant difference in the IgG content of the colostrum between the left and right halves of the udder. The further evaluation is therefore based on the mean of both halves.

The IgG content in the colostrum was 1.95 log10 mg/mL immediately after birth and decreased over 1.76 (6 h) and 1.56 (12 h) to 1.40 log10 mg/mL after 24 hours. The value at birth was significantly higher than all later ones, the value after 6 h higher than those after 12 h and 24 h; 12 h and 24 h did not differ. In the regression model, IgG decreased by 0.0244 log10 mg/mL per hour.

Limitations of the study

• Very small sample size: Nine mare-foal pairs of one breed from one stud farm were evaluated; the authors themselves describe the work as a preliminary study. Breed-specific reference ranges cannot yet be derived from this.
• Test for horse IgG: IgG was measured with an SRID test developed for horses because no donkey-specific test was available. A validation for donkey IgG is not described, the absolute values should therefore be compared with caution.
• Table values do not quite match: From the individual values in Table 1, editorial recalculation results in mean values of 1.94, 1.69, 1.53 and 1.37 log10 mg/mL, Table 2 states 1.95, 1.76, 1.56 and 1.40. The standard deviations given in Table 2 (0.97–1.49) are not compatible with the spread of the individual values (around 0.12–0.29 log10 units).
• Unclear units and information: The weight gain of 0.841 kg is given without a time reference; the abbreviation stands for a weekly gain, which would only amount to around 3.4 kg over 28 days. No coefficients are reported for the correlations, and the collected colostrum volume was not recorded.
• Conspicuous individual values: In Table 1, the value 1.41 log10 mg/mL occurs very frequently, individual samples are at 0.76. Whether these are the measurement limits of the test is not explained by the article.

Level of evidence: Animal study – describes measured values in the studied animals and their milk, no statement about effects in humans.

Our assessment

The study describes the colostrum of the first 24 hours after birth, which is reserved for the foals, and the IgG course in the foals' blood. No statements about the composition of later collected donkey milk or effects in humans can be derived from this.

Source: Turini L., Bonelli F., Nocera I., Battaglia F., Meucci V., Panzani D., Mele M., Sgorbini M. (2020). Evaluation of jennies' colostrum: IgG concentrations and absorption in the donkey foals. A preliminary study. Heliyon. DOI: 10.1016/j.heliyon.2020.e04598 · Summarized by the DON DONKEY'S editorial team, as of: October 2026.

End of the study summary. The study was conducted independently of DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.