Effects of breed, farm intensiveness, and cow productivity on infrared predicted milk urea

Abstract

Milk urea content is receiving growing interest from science and industry as a tool to infer the protein adequacy of dairy cows' diets, nitrogen excretion and its environmental impact, and efficiency of animals' protein metabolism. Fourier-transform infrared (FTIR) prediction is a high-throughput method for rapidly and cheaply evaluating milk urea content at the population level. Existing knowledge of the major sources of variation (e.g., year, season, farming system, individual herd, and the cow's breed, parity, stage of lactation, and productive potential) is fragmentary. The objective of this work was to study at the population level the simultaneous effects of all the major sources of variation and their most important interactions. Milk urea content in 1,759,706 test day milk samples collected from 291,129 lactations of 115,819 cows from 6,430 herds over 8 yr was predicted by FTIR. The milk urea content data (and also milk protein percentage, for comparison) were analyzed using a linear model that included the effects of parity, days in milk (DIM) class, year, month, herd intensiveness level, cow productivity level, breed, and herd intensiveness and cow productivity levels within breed. All sources of variation of milk urea content proved highly significant, the most important in terms of F-value being breed > year > herd intensiveness level > parity. The ranking for milk protein was very different (DIM class > herd intensiveness level > parity > breed). The patterns of the least squares means for urea and protein contents of milk were also very different and sometimes contrasting. The seasonal variation in urea was sinusoidal. Urea content increased during the first 4 mo of lactation and then remained almost stable before decreasing after 11 mo. Specialized dairy breeds had lower average milk urea content than dual-purpose breeds; in the former case it was lower in Holsteins than in Brown Swiss, and in the latter it was lower in Simmentals than in Alpine Greys. The effect of herd intensiveness level was much stronger than the effect of cow productivity level; the increase in milk urea with increasing herd average daily milk yield was almost linear in the case of dairy breeds but curvilinear in dual-purpose breeds. The large differences in breed and the modest relationships with the cow's productive potential require further analysis at the genetic level to obtain information of potential use in genetic improvement of the dairy cow populations.

Subclinical mastitis in Jersey dairy cows and its effects on productivity and inflammatory markers

“…Total solids represent all milk constituents and can thus be used as an evaluation parameter for quality (Alessio et al, 2021). The decrease in MUN values in the SubG can be explained by the variable level of urea in the milk of the same herd of cows, for which the predisposing factors are age at first calving, number of lactations, stage of lactation, breed (Bittante, 2022), and energy and mineral imbalance caused by inflammation (Martins et al, 2021). Cows with lower metabolic conditions may have elevated milk urea levels, which are closely related to blood urea concentrations (DePeters et al, 1992;Gustafsson & Palmquist, 1993), suggesting that the elimination of urea, which requires energy, is impaired in cows with a low glycemic index (Gross et al, 2020).…”

Interpretable machine learning reveals microbiome signatures strongly associated with dairy cow milk urea nitrogen

“… 13 measured MUN in 14 herds and found that MUN concentrations ranged from 11 to 23 mg/dL. In the measurement of MUN, Bittante 14 studied different breeds of dairy cows (Total 115819) and found that the mean value of MUN was 21.1 mg/dL. Currently, nitrogen wastage in dairy herds is more prevalent.…”

Moderní aspekty vědy

“…It is known that the physiological maturity of newborn animals depends on the physiological, biochemical and morphological status of the mother cow during the dry period, a change in which initiates the appearance of disorders in the functional system "mother-fetus", which affect the harmonious development of the fetus in a pregnant cow. Therefore, by correcting the vital processes in the body of dry cows, it is possible to increase the viability of newborn calves [37].…”