TY - JOUR
T1 - Effect of protein concentrate mixtures and dietary addition of exogenous phytase on major milk minerals and proteins, including casein phosphorylation
AU - Poulsen, N. A.
AU - Giagnoni, G.
AU - Johansen, M.
AU - Lund, P.
AU - Larsen, L. B.
N1 - Publisher Copyright:
© 2021 American Dairy Science Association
PY - 2021/9
Y1 - 2021/9
N2 - Variations in major milk minerals, proteins, and their posttranslational modifications are largely under genetic influence, whereas the effect of nongenetic factors is less studied. Through a controlled feeding experiment (incomplete balanced Latin square design), the effect of concentrate mixtures, based on fava beans, rapeseed meal, or soybean meal as main P and protein sources, on milk composition was examined under typical Danish management conditions. Concentrations of P, Ca, and Mg, together with proteomics for relative quantification of major milk proteins and their isoforms, were analyzed in milk samples from 24 cows sampled in 4 periods. Each cow was fed 1 of the 3 diets in each period with or without addition of exogenous phytase. Cows were blocked by lactation stage into early and mid-lactation (23.3 ± 6.7 and 176 ± 15 d in milk, respectively, at the beginning of the experiment, mean ± standard deviation). Significant effects of feed concentrate mixture were observed for milk protein concentration, milk urea nitrogen, citrate, and the percentage of mixed and preformed fatty acids as well as mineral composition, and their distributions within micellar or serum phases. Furthermore, relative contents of αS1-casein (CN) 9P form and unglycosylated κ-CN and thereby phosphorylation degree of αS1-CN (PD) and the glycosylation degree of κ-CN were found to be significantly affected by these diets. To our knowledge, we are the first to document that feed concentrate mixture can affect the relative concentrations of αS1-CN phosphorylation isoforms in milk, and the results suggested an effect on αS1-CN 9P and PD, but not on αS1-CN 8P. Furthermore, although only significant for αS1-CN 8P, we found a lower relative concentration of αS1-CN 8P and higher αS1-CN 9P (and thus higher PD) in milk from cows in mid compared with early lactation. Also, protein concentration and concentration of Mg in skim milk and serum as well as relative concentration of α-lactalbumin were found to be significantly affected by lactation stage. Addition of dietary exogenous phytase only had a minor effect on milk composition or functionality with significant effect detected for α-lactalbumin and micellar Mg concentration.
AB - Variations in major milk minerals, proteins, and their posttranslational modifications are largely under genetic influence, whereas the effect of nongenetic factors is less studied. Through a controlled feeding experiment (incomplete balanced Latin square design), the effect of concentrate mixtures, based on fava beans, rapeseed meal, or soybean meal as main P and protein sources, on milk composition was examined under typical Danish management conditions. Concentrations of P, Ca, and Mg, together with proteomics for relative quantification of major milk proteins and their isoforms, were analyzed in milk samples from 24 cows sampled in 4 periods. Each cow was fed 1 of the 3 diets in each period with or without addition of exogenous phytase. Cows were blocked by lactation stage into early and mid-lactation (23.3 ± 6.7 and 176 ± 15 d in milk, respectively, at the beginning of the experiment, mean ± standard deviation). Significant effects of feed concentrate mixture were observed for milk protein concentration, milk urea nitrogen, citrate, and the percentage of mixed and preformed fatty acids as well as mineral composition, and their distributions within micellar or serum phases. Furthermore, relative contents of αS1-casein (CN) 9P form and unglycosylated κ-CN and thereby phosphorylation degree of αS1-CN (PD) and the glycosylation degree of κ-CN were found to be significantly affected by these diets. To our knowledge, we are the first to document that feed concentrate mixture can affect the relative concentrations of αS1-CN phosphorylation isoforms in milk, and the results suggested an effect on αS1-CN 9P and PD, but not on αS1-CN 8P. Furthermore, although only significant for αS1-CN 8P, we found a lower relative concentration of αS1-CN 8P and higher αS1-CN 9P (and thus higher PD) in milk from cows in mid compared with early lactation. Also, protein concentration and concentration of Mg in skim milk and serum as well as relative concentration of α-lactalbumin were found to be significantly affected by lactation stage. Addition of dietary exogenous phytase only had a minor effect on milk composition or functionality with significant effect detected for α-lactalbumin and micellar Mg concentration.
KW - faba bean
KW - fava bean
KW - rapeseed
KW - ruminant
KW - soybean
UR - http://www.scopus.com/inward/record.url?scp=85107362761&partnerID=8YFLogxK
U2 - 10.3168/jds.2020-20075
DO - 10.3168/jds.2020-20075
M3 - Journal article
C2 - 34099285
AN - SCOPUS:85107362761
SN - 0022-0302
VL - 104
SP - 9801
EP - 9812
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 9
ER -