Influence of Estrus on the Milk Characteristics and Mid-Infrared Spectra of Dairy Cows

Abstract

Milk produced by dairy cows is a complex combination of many components. However, at present, changes in only a few milk components (e.g., fat, protein, and lactose) during the estrus cycle in dairy cows have been documented. Mid-infrared (MIR) spectroscopy is a worldwide method routinely used for milk analysis, as MIR spectra reflect the global composition of milk. Therefore, this study aimed to investigate the changes in milk MIR spectra and milk production traits (fat, protein, lactose, urea, total solids (TS), and solid not fat (SnF)) due to estrus. Cows that were successfully inseminated, leading to conception, were included. Cows confirmed to be pregnant were considered to be in estrus at the day of insemination (day 0). A general linear mixed model, which included the random effect of cows, the fixed classification effects of parity number, days in relation to estrus, as well as the interaction between parity number and days in relation to estrus, was applied to investigate the changes in milk production traits and 1060 milk infrared wavenumbers, ranging from 925 to 5011 cm−1, of 371 records from 162 Holstein cows on the days before (day −3, day −2, and day −1) and on the day of estrus (day 0). The days in relation to estrus had a significant effect on fat, protein, urea, TS, and SnF, whose contents increased from day −3 to day 0. Lactose did not seem to be significantly influenced by the occurrence of estrus. The days in relation to estrus had significant effects on the majority of the wavenumbers. Besides, we found that some of the wavenumbers in the water absorption regions were significantly changed on the days before and on the day of estrus. This suggests that these wavenumbers may contain useful information. In conclusion, the changes in the milk composition due to estrus can be observed through the analysis of the milk MIR spectrum. Further analyses are warranted to more deeply explore the potential use of milk MIR spectra in the detection of estrus.

The Difference of Milk-Derived Extracellular Vesicles from Cow Colostrum and Mature Milk on miRNAs Expression and Protecting Intestinal Epithelial Cells against Lipopolysaccharide Damage

“…We collected 5 colostrum (days 3 postpartum) and 5 mature milk (beyond day 30 postpartum) samples from the lactating Holstein dairy with 1 parity in a commercial dairy farm in the Hebei province of China. The feeding and management of cows were performed as previously described [78]. Simply, the cows were provided with total mixed ration at 08:00, 16:00, and 24:00.…”

Quality characteristics and nutrient contents of Bactrian camel milk as determined by mid‐infrared spectroscopy

“…Du et al . (2021) and Shijie et al . (2021) established cow pregnancy, α‐S1‐casein and κ‐casein prediction models.…”

“…In terms of cow milk determination, there are numerous literature reports on the use of MIRS to predict the mineral (Christophe et al 2021), lactoferrin (Nayeri et al 2020;Soyeurt et al 2020) and fatty acid (Fleming et al 2018;Lopez-Villalobos et al 2020) contents of cow milk. Du et al (2021) and Shijie et al (2021) established cow pregnancy, a-S1-casein and j-casein prediction models. However, no MIRS-based prediction model for camel milk has been reported.…”

Influence of Estrus on Dairy Cow Milk Exosomal miRNAs and Their Role in Hormone Secretion by Granulosa Cells

“…Therefore, estrus could induce changes in the specific milk fatty acid profiles [12,13]. In addition, Du et al [14] reported that estrus had a significant effect on milk production, including fat, protein, urea, total solids, and solid not fat, whose contents increased in estrous compared to non-estrous cows. Moreover, estrus also could change some of the wavenumbers in the water-absorption regions by mid-infrared spectroscopy detected on the days before and on the day of estrus.…”