Increasing importance is given to healthy diets and to satisfy this
demand, the benchmark of milk quality now includes also the
specific composition of the lipid and protein fractions in milk.
Milk fat has been criticized because of its higher concentration
of saturated fatty acids (SFA) and low concentrations of monounsaturated
(MUFA) and poly- unsaturated (PUFA), but fatty acids
(FA) profile can be improved via genetic selection, which can
provide a more permanent solution compared with managementrelated
approaches. The aim of this work is to estimate the correlations
among groups of milk FA, namely SFA, unsaturated
(UFA), MUFA and PUFA, and EBVs (kg of protein EBVp, kg of fat
EBVf) in Italian Simmental (IS) and Italian Holstein (IH) cattle.
Milk sampling was conducted in 6 commercial farms of IS and 4commercial farms of IH. Cows had free access to water and a ad
libitum total mixed ration offered twice a day. The day of official
milk recording, 100 mL of milk individual samples were collected
and split in two 50 mL aliquots, one used for the determination
of protein, fat, lactose and for somatic cell count (SCC) and the
second frozen at -20\ub0C within 2 hours for fatty acid analyses.
Before statistical analysis, animals were classified for parity with
ordinal value of 1 for first calving, 2 for second calving and 3 for
cows with more than 2 calving. Analysis was performed with a
mixed model, with fixed effects of Breed and Parity and random
effect of Farm and the linear relationships with DIM and with
EBVs within breeds. Results evidenced a significant correlation
between SFA, UFA, PUFA, MUFA with EBVp and EBVf in both
breeds. Relevant to highlight is the ratio rumenic/(vacenic+rumenic), resulted to be statistically significant considering
breeds as well as EBVp and EBVf. This may be due to a
divergent selection for the gene involved in vaccenic/rumenic
methabolism in the two breeds while the significant association
with EBVf and EBVp suggests the existence of a genetic variability
of the trait within breeds. Daily CH4 emission (g/kg of FPCM),
estimated on the basis of fatty acid profile, was also correlated
with EBVf and EBVp. Although further investigations are
required, these traits can be considered in breeding programs for
the next generation dairy cows
